From b22da3d8526a935aa31e086e63f60ff3246cb61c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Sat, 09 Dec 2023 07:24:11 +0000
Subject: [PATCH] add stmac read mac form eeprom
---
kernel/drivers/char/random.c | 3373 +++++++++++++++++++++++-----------------------------------
1 files changed, 1,339 insertions(+), 2,034 deletions(-)
diff --git a/kernel/drivers/char/random.c b/kernel/drivers/char/random.c
index 6e1cbc5..56bcf96 100644
--- a/kernel/drivers/char/random.c
+++ b/kernel/drivers/char/random.c
@@ -1,310 +1,26 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
/*
- * random.c -- A strong random number generator
- *
- * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All
- * Rights Reserved.
- *
+ * Copyright (C) 2017-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
* Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
+ * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All rights reserved.
*
- * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
- * rights reserved.
+ * This driver produces cryptographically secure pseudorandom data. It is divided
+ * into roughly six sections, each with a section header:
*
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, and the entire permission notice in its entirety,
- * including the disclaimer of warranties.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
+ * - Initialization and readiness waiting.
+ * - Fast key erasure RNG, the "crng".
+ * - Entropy accumulation and extraction routines.
+ * - Entropy collection routines.
+ * - Userspace reader/writer interfaces.
+ * - Sysctl interface.
*
- * ALTERNATIVELY, this product may be distributed under the terms of
- * the GNU General Public License, in which case the provisions of the GPL are
- * required INSTEAD OF the above restrictions. (This clause is
- * necessary due to a potential bad interaction between the GPL and
- * the restrictions contained in a BSD-style copyright.)
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
- * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
- * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
- * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
- * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
- * DAMAGE.
- */
-
-/*
- * (now, with legal B.S. out of the way.....)
- *
- * This routine gathers environmental noise from device drivers, etc.,
- * and returns good random numbers, suitable for cryptographic use.
- * Besides the obvious cryptographic uses, these numbers are also good
- * for seeding TCP sequence numbers, and other places where it is
- * desirable to have numbers which are not only random, but hard to
- * predict by an attacker.
- *
- * Theory of operation
- * ===================
- *
- * Computers are very predictable devices. Hence it is extremely hard
- * to produce truly random numbers on a computer --- as opposed to
- * pseudo-random numbers, which can easily generated by using a
- * algorithm. Unfortunately, it is very easy for attackers to guess
- * the sequence of pseudo-random number generators, and for some
- * applications this is not acceptable. So instead, we must try to
- * gather "environmental noise" from the computer's environment, which
- * must be hard for outside attackers to observe, and use that to
- * generate random numbers. In a Unix environment, this is best done
- * from inside the kernel.
- *
- * Sources of randomness from the environment include inter-keyboard
- * timings, inter-interrupt timings from some interrupts, and other
- * events which are both (a) non-deterministic and (b) hard for an
- * outside observer to measure. Randomness from these sources are
- * added to an "entropy pool", which is mixed using a CRC-like function.
- * This is not cryptographically strong, but it is adequate assuming
- * the randomness is not chosen maliciously, and it is fast enough that
- * the overhead of doing it on every interrupt is very reasonable.
- * As random bytes are mixed into the entropy pool, the routines keep
- * an *estimate* of how many bits of randomness have been stored into
- * the random number generator's internal state.
- *
- * When random bytes are desired, they are obtained by taking the SHA
- * hash of the contents of the "entropy pool". The SHA hash avoids
- * exposing the internal state of the entropy pool. It is believed to
- * be computationally infeasible to derive any useful information
- * about the input of SHA from its output. Even if it is possible to
- * analyze SHA in some clever way, as long as the amount of data
- * returned from the generator is less than the inherent entropy in
- * the pool, the output data is totally unpredictable. For this
- * reason, the routine decreases its internal estimate of how many
- * bits of "true randomness" are contained in the entropy pool as it
- * outputs random numbers.
- *
- * If this estimate goes to zero, the routine can still generate
- * random numbers; however, an attacker may (at least in theory) be
- * able to infer the future output of the generator from prior
- * outputs. This requires successful cryptanalysis of SHA, which is
- * not believed to be feasible, but there is a remote possibility.
- * Nonetheless, these numbers should be useful for the vast majority
- * of purposes.
- *
- * Exported interfaces ---- output
- * ===============================
- *
- * There are four exported interfaces; two for use within the kernel,
- * and two or use from userspace.
- *
- * Exported interfaces ---- userspace output
- * -----------------------------------------
- *
- * The userspace interfaces are two character devices /dev/random and
- * /dev/urandom. /dev/random is suitable for use when very high
- * quality randomness is desired (for example, for key generation or
- * one-time pads), as it will only return a maximum of the number of
- * bits of randomness (as estimated by the random number generator)
- * contained in the entropy pool.
- *
- * The /dev/urandom device does not have this limit, and will return
- * as many bytes as are requested. As more and more random bytes are
- * requested without giving time for the entropy pool to recharge,
- * this will result in random numbers that are merely cryptographically
- * strong. For many applications, however, this is acceptable.
- *
- * Exported interfaces ---- kernel output
- * --------------------------------------
- *
- * The primary kernel interface is
- *
- * void get_random_bytes(void *buf, int nbytes);
- *
- * This interface will return the requested number of random bytes,
- * and place it in the requested buffer. This is equivalent to a
- * read from /dev/urandom.
- *
- * For less critical applications, there are the functions:
- *
- * u32 get_random_u32()
- * u64 get_random_u64()
- * unsigned int get_random_int()
- * unsigned long get_random_long()
- *
- * These are produced by a cryptographic RNG seeded from get_random_bytes,
- * and so do not deplete the entropy pool as much. These are recommended
- * for most in-kernel operations *if the result is going to be stored in
- * the kernel*.
- *
- * Specifically, the get_random_int() family do not attempt to do
- * "anti-backtracking". If you capture the state of the kernel (e.g.
- * by snapshotting the VM), you can figure out previous get_random_int()
- * return values. But if the value is stored in the kernel anyway,
- * this is not a problem.
- *
- * It *is* safe to expose get_random_int() output to attackers (e.g. as
- * network cookies); given outputs 1..n, it's not feasible to predict
- * outputs 0 or n+1. The only concern is an attacker who breaks into
- * the kernel later; the get_random_int() engine is not reseeded as
- * often as the get_random_bytes() one.
- *
- * get_random_bytes() is needed for keys that need to stay secret after
- * they are erased from the kernel. For example, any key that will
- * be wrapped and stored encrypted. And session encryption keys: we'd
- * like to know that after the session is closed and the keys erased,
- * the plaintext is unrecoverable to someone who recorded the ciphertext.
- *
- * But for network ports/cookies, stack canaries, PRNG seeds, address
- * space layout randomization, session *authentication* keys, or other
- * applications where the sensitive data is stored in the kernel in
- * plaintext for as long as it's sensitive, the get_random_int() family
- * is just fine.
- *
- * Consider ASLR. We want to keep the address space secret from an
- * outside attacker while the process is running, but once the address
- * space is torn down, it's of no use to an attacker any more. And it's
- * stored in kernel data structures as long as it's alive, so worrying
- * about an attacker's ability to extrapolate it from the get_random_int()
- * CRNG is silly.
- *
- * Even some cryptographic keys are safe to generate with get_random_int().
- * In particular, keys for SipHash are generally fine. Here, knowledge
- * of the key authorizes you to do something to a kernel object (inject
- * packets to a network connection, or flood a hash table), and the
- * key is stored with the object being protected. Once it goes away,
- * we no longer care if anyone knows the key.
- *
- * prandom_u32()
- * -------------
- *
- * For even weaker applications, see the pseudorandom generator
- * prandom_u32(), prandom_max(), and prandom_bytes(). If the random
- * numbers aren't security-critical at all, these are *far* cheaper.
- * Useful for self-tests, random error simulation, randomized backoffs,
- * and any other application where you trust that nobody is trying to
- * maliciously mess with you by guessing the "random" numbers.
- *
- * Exported interfaces ---- input
- * ==============================
- *
- * The current exported interfaces for gathering environmental noise
- * from the devices are:
- *
- * void add_device_randomness(const void *buf, unsigned int size);
- * void add_input_randomness(unsigned int type, unsigned int code,
- * unsigned int value);
- * void add_interrupt_randomness(int irq, int irq_flags);
- * void add_disk_randomness(struct gendisk *disk);
- *
- * add_device_randomness() is for adding data to the random pool that
- * is likely to differ between two devices (or possibly even per boot).
- * This would be things like MAC addresses or serial numbers, or the
- * read-out of the RTC. This does *not* add any actual entropy to the
- * pool, but it initializes the pool to different values for devices
- * that might otherwise be identical and have very little entropy
- * available to them (particularly common in the embedded world).
- *
- * add_input_randomness() uses the input layer interrupt timing, as well as
- * the event type information from the hardware.
- *
- * add_interrupt_randomness() uses the interrupt timing as random
- * inputs to the entropy pool. Using the cycle counters and the irq source
- * as inputs, it feeds the randomness roughly once a second.
- *
- * add_disk_randomness() uses what amounts to the seek time of block
- * layer request events, on a per-disk_devt basis, as input to the
- * entropy pool. Note that high-speed solid state drives with very low
- * seek times do not make for good sources of entropy, as their seek
- * times are usually fairly consistent.
- *
- * All of these routines try to estimate how many bits of randomness a
- * particular randomness source. They do this by keeping track of the
- * first and second order deltas of the event timings.
- *
- * Ensuring unpredictability at system startup
- * ============================================
- *
- * When any operating system starts up, it will go through a sequence
- * of actions that are fairly predictable by an adversary, especially
- * if the start-up does not involve interaction with a human operator.
- * This reduces the actual number of bits of unpredictability in the
- * entropy pool below the value in entropy_count. In order to
- * counteract this effect, it helps to carry information in the
- * entropy pool across shut-downs and start-ups. To do this, put the
- * following lines an appropriate script which is run during the boot
- * sequence:
- *
- * echo "Initializing random number generator..."
- * random_seed=/var/run/random-seed
- * # Carry a random seed from start-up to start-up
- * # Load and then save the whole entropy pool
- * if [ -f $random_seed ]; then
- * cat $random_seed >/dev/urandom
- * else
- * touch $random_seed
- * fi
- * chmod 600 $random_seed
- * dd if=/dev/urandom of=$random_seed count=1 bs=512
- *
- * and the following lines in an appropriate script which is run as
- * the system is shutdown:
- *
- * # Carry a random seed from shut-down to start-up
- * # Save the whole entropy pool
- * echo "Saving random seed..."
- * random_seed=/var/run/random-seed
- * touch $random_seed
- * chmod 600 $random_seed
- * dd if=/dev/urandom of=$random_seed count=1 bs=512
- *
- * For example, on most modern systems using the System V init
- * scripts, such code fragments would be found in
- * /etc/rc.d/init.d/random. On older Linux systems, the correct script
- * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
- *
- * Effectively, these commands cause the contents of the entropy pool
- * to be saved at shut-down time and reloaded into the entropy pool at
- * start-up. (The 'dd' in the addition to the bootup script is to
- * make sure that /etc/random-seed is different for every start-up,
- * even if the system crashes without executing rc.0.) Even with
- * complete knowledge of the start-up activities, predicting the state
- * of the entropy pool requires knowledge of the previous history of
- * the system.
- *
- * Configuring the /dev/random driver under Linux
- * ==============================================
- *
- * The /dev/random driver under Linux uses minor numbers 8 and 9 of
- * the /dev/mem major number (#1). So if your system does not have
- * /dev/random and /dev/urandom created already, they can be created
- * by using the commands:
- *
- * mknod /dev/random c 1 8
- * mknod /dev/urandom c 1 9
- *
- * Acknowledgements:
- * =================
- *
- * Ideas for constructing this random number generator were derived
- * from Pretty Good Privacy's random number generator, and from private
- * discussions with Phil Karn. Colin Plumb provided a faster random
- * number generator, which speed up the mixing function of the entropy
- * pool, taken from PGPfone. Dale Worley has also contributed many
- * useful ideas and suggestions to improve this driver.
- *
- * Any flaws in the design are solely my responsibility, and should
- * not be attributed to the Phil, Colin, or any of authors of PGP.
- *
- * Further background information on this topic may be obtained from
- * RFC 1750, "Randomness Recommendations for Security", by Donald
- * Eastlake, Steve Crocker, and Jeff Schiller.
+ * The high level overview is that there is one input pool, into which
+ * various pieces of data are hashed. Prior to initialization, some of that
+ * data is then "credited" as having a certain number of bits of entropy.
+ * When enough bits of entropy are available, the hash is finalized and
+ * handed as a key to a stream cipher that expands it indefinitely for
+ * various consumers. This key is periodically refreshed as the various
+ * entropy collectors, described below, add data to the input pool.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -327,8 +43,6 @@
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/percpu.h>
-#include <linux/cryptohash.h>
-#include <linux/fips.h>
#include <linux/ptrace.h>
#include <linux/workqueue.h>
#include <linux/irq.h>
@@ -336,759 +50,805 @@
#include <linux/syscalls.h>
#include <linux/completion.h>
#include <linux/uuid.h>
-#include <crypto/chacha.h>
-
-#include <asm/processor.h>
#include <linux/uaccess.h>
+#include <linux/siphash.h>
+#include <linux/uio.h>
+#include <crypto/chacha.h>
+#include <crypto/blake2s.h>
+#include <asm/processor.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
#include <asm/io.h>
-#define CREATE_TRACE_POINTS
-#include <trace/events/random.h>
-
-/* #define ADD_INTERRUPT_BENCH */
-
-/*
- * Configuration information
- */
-#define INPUT_POOL_SHIFT 12
-#define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5))
-#define OUTPUT_POOL_SHIFT 10
-#define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5))
-#define EXTRACT_SIZE 10
-
-
-#define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
-
-/*
- * To allow fractional bits to be tracked, the entropy_count field is
- * denominated in units of 1/8th bits.
- *
- * 2*(ENTROPY_SHIFT + poolbitshift) must <= 31, or the multiply in
- * credit_entropy_bits() needs to be 64 bits wide.
- */
-#define ENTROPY_SHIFT 3
-#define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)
-
-/*
- * If the entropy count falls under this number of bits, then we
- * should wake up processes which are selecting or polling on write
- * access to /dev/random.
- */
-static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
-
-/*
- * Originally, we used a primitive polynomial of degree .poolwords
- * over GF(2). The taps for various sizes are defined below. They
- * were chosen to be evenly spaced except for the last tap, which is 1
- * to get the twisting happening as fast as possible.
- *
- * For the purposes of better mixing, we use the CRC-32 polynomial as
- * well to make a (modified) twisted Generalized Feedback Shift
- * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR
- * generators. ACM Transactions on Modeling and Computer Simulation
- * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted
- * GFSR generators II. ACM Transactions on Modeling and Computer
- * Simulation 4:254-266)
- *
- * Thanks to Colin Plumb for suggesting this.
- *
- * The mixing operation is much less sensitive than the output hash,
- * where we use SHA-1. All that we want of mixing operation is that
- * it be a good non-cryptographic hash; i.e. it not produce collisions
- * when fed "random" data of the sort we expect to see. As long as
- * the pool state differs for different inputs, we have preserved the
- * input entropy and done a good job. The fact that an intelligent
- * attacker can construct inputs that will produce controlled
- * alterations to the pool's state is not important because we don't
- * consider such inputs to contribute any randomness. The only
- * property we need with respect to them is that the attacker can't
- * increase his/her knowledge of the pool's state. Since all
- * additions are reversible (knowing the final state and the input,
- * you can reconstruct the initial state), if an attacker has any
- * uncertainty about the initial state, he/she can only shuffle that
- * uncertainty about, but never cause any collisions (which would
- * decrease the uncertainty).
- *
- * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
- * Videau in their paper, "The Linux Pseudorandom Number Generator
- * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their
- * paper, they point out that we are not using a true Twisted GFSR,
- * since Matsumoto & Kurita used a trinomial feedback polynomial (that
- * is, with only three taps, instead of the six that we are using).
- * As a result, the resulting polynomial is neither primitive nor
- * irreducible, and hence does not have a maximal period over
- * GF(2**32). They suggest a slight change to the generator
- * polynomial which improves the resulting TGFSR polynomial to be
- * irreducible, which we have made here.
- */
-static const struct poolinfo {
- int poolbitshift, poolwords, poolbytes, poolfracbits;
-#define S(x) ilog2(x)+5, (x), (x)*4, (x) << (ENTROPY_SHIFT+5)
- int tap1, tap2, tap3, tap4, tap5;
-} poolinfo_table[] = {
- /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */
- /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
- { S(128), 104, 76, 51, 25, 1 },
-};
-
-/*
- * Static global variables
- */
-static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
-static struct fasync_struct *fasync;
-
-static DEFINE_SPINLOCK(random_ready_list_lock);
-static LIST_HEAD(random_ready_list);
-
-struct crng_state {
- __u32 state[16];
- unsigned long init_time;
- spinlock_t lock;
-};
-
-static struct crng_state primary_crng = {
- .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
-};
-
-/*
- * crng_init = 0 --> Uninitialized
- * 1 --> Initialized
- * 2 --> Initialized from input_pool
- *
- * crng_init is protected by primary_crng->lock, and only increases
- * its value (from 0->1->2).
- */
-static int crng_init = 0;
-#define crng_ready() (likely(crng_init > 1))
-static int crng_init_cnt = 0;
-static unsigned long crng_global_init_time = 0;
-#define CRNG_INIT_CNT_THRESH (2*CHACHA_KEY_SIZE)
-static void _extract_crng(struct crng_state *crng, __u8 out[CHACHA_BLOCK_SIZE]);
-static void _crng_backtrack_protect(struct crng_state *crng,
- __u8 tmp[CHACHA_BLOCK_SIZE], int used);
-static void process_random_ready_list(void);
-static void _get_random_bytes(void *buf, int nbytes);
-
-static struct ratelimit_state unseeded_warning =
- RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
-static struct ratelimit_state urandom_warning =
- RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
-
-static int ratelimit_disable __read_mostly;
-
-module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
-MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
-
-/**********************************************************************
- *
- * OS independent entropy store. Here are the functions which handle
- * storing entropy in an entropy pool.
- *
- **********************************************************************/
-
-struct entropy_store;
-struct entropy_store {
- /* read-only data: */
- const struct poolinfo *poolinfo;
- __u32 *pool;
- const char *name;
-
- /* read-write data: */
- spinlock_t lock;
- unsigned short add_ptr;
- unsigned short input_rotate;
- int entropy_count;
- unsigned int initialized:1;
- unsigned int last_data_init:1;
- __u8 last_data[EXTRACT_SIZE];
-};
-
-static ssize_t extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int min, int rsvd);
-static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int fips);
-
-static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
-static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
-
-static struct entropy_store input_pool = {
- .poolinfo = &poolinfo_table[0],
- .name = "input",
- .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
- .pool = input_pool_data
-};
-
-static __u32 const twist_table[8] = {
- 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
- 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
-
-/*
- * This function adds bytes into the entropy "pool". It does not
- * update the entropy estimate. The caller should call
- * credit_entropy_bits if this is appropriate.
- *
- * The pool is stirred with a primitive polynomial of the appropriate
- * degree, and then twisted. We twist by three bits at a time because
- * it's cheap to do so and helps slightly in the expected case where
- * the entropy is concentrated in the low-order bits.
- */
-static void _mix_pool_bytes(struct entropy_store *r, const void *in,
- int nbytes)
-{
- unsigned long i, tap1, tap2, tap3, tap4, tap5;
- int input_rotate;
- int wordmask = r->poolinfo->poolwords - 1;
- const char *bytes = in;
- __u32 w;
-
- tap1 = r->poolinfo->tap1;
- tap2 = r->poolinfo->tap2;
- tap3 = r->poolinfo->tap3;
- tap4 = r->poolinfo->tap4;
- tap5 = r->poolinfo->tap5;
-
- input_rotate = r->input_rotate;
- i = r->add_ptr;
-
- /* mix one byte at a time to simplify size handling and churn faster */
- while (nbytes--) {
- w = rol32(*bytes++, input_rotate);
- i = (i - 1) & wordmask;
-
- /* XOR in the various taps */
- w ^= r->pool[i];
- w ^= r->pool[(i + tap1) & wordmask];
- w ^= r->pool[(i + tap2) & wordmask];
- w ^= r->pool[(i + tap3) & wordmask];
- w ^= r->pool[(i + tap4) & wordmask];
- w ^= r->pool[(i + tap5) & wordmask];
-
- /* Mix the result back in with a twist */
- r->pool[i] = (w >> 3) ^ twist_table[w & 7];
-
- /*
- * Normally, we add 7 bits of rotation to the pool.
- * At the beginning of the pool, add an extra 7 bits
- * rotation, so that successive passes spread the
- * input bits across the pool evenly.
- */
- input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
- }
-
- r->input_rotate = input_rotate;
- r->add_ptr = i;
-}
-
-static void __mix_pool_bytes(struct entropy_store *r, const void *in,
- int nbytes)
-{
- trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
- _mix_pool_bytes(r, in, nbytes);
-}
-
-static void mix_pool_bytes(struct entropy_store *r, const void *in,
- int nbytes)
-{
- unsigned long flags;
-
- trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
- spin_lock_irqsave(&r->lock, flags);
- _mix_pool_bytes(r, in, nbytes);
- spin_unlock_irqrestore(&r->lock, flags);
-}
-
-struct fast_pool {
- __u32 pool[4];
- unsigned long last;
- unsigned short reg_idx;
- unsigned char count;
-};
-
-/*
- * This is a fast mixing routine used by the interrupt randomness
- * collector. It's hardcoded for an 128 bit pool and assumes that any
- * locks that might be needed are taken by the caller.
- */
-static void fast_mix(struct fast_pool *f)
-{
- __u32 a = f->pool[0], b = f->pool[1];
- __u32 c = f->pool[2], d = f->pool[3];
-
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
-
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
-
- f->pool[0] = a; f->pool[1] = b;
- f->pool[2] = c; f->pool[3] = d;
- f->count++;
-}
-
-static void process_random_ready_list(void)
-{
- unsigned long flags;
- struct random_ready_callback *rdy, *tmp;
-
- spin_lock_irqsave(&random_ready_list_lock, flags);
- list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
- struct module *owner = rdy->owner;
-
- list_del_init(&rdy->list);
- rdy->func(rdy);
- module_put(owner);
- }
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
-}
-
-/*
- * Credit (or debit) the entropy store with n bits of entropy.
- * Use credit_entropy_bits_safe() if the value comes from userspace
- * or otherwise should be checked for extreme values.
- */
-static void credit_entropy_bits(struct entropy_store *r, int nbits)
-{
- int entropy_count, orig, has_initialized = 0;
- const int pool_size = r->poolinfo->poolfracbits;
- int nfrac = nbits << ENTROPY_SHIFT;
-
- if (!nbits)
- return;
-
-retry:
- entropy_count = orig = READ_ONCE(r->entropy_count);
- if (nfrac < 0) {
- /* Debit */
- entropy_count += nfrac;
- } else {
- /*
- * Credit: we have to account for the possibility of
- * overwriting already present entropy. Even in the
- * ideal case of pure Shannon entropy, new contributions
- * approach the full value asymptotically:
- *
- * entropy <- entropy + (pool_size - entropy) *
- * (1 - exp(-add_entropy/pool_size))
- *
- * For add_entropy <= pool_size/2 then
- * (1 - exp(-add_entropy/pool_size)) >=
- * (add_entropy/pool_size)*0.7869...
- * so we can approximate the exponential with
- * 3/4*add_entropy/pool_size and still be on the
- * safe side by adding at most pool_size/2 at a time.
- *
- * The use of pool_size-2 in the while statement is to
- * prevent rounding artifacts from making the loop
- * arbitrarily long; this limits the loop to log2(pool_size)*2
- * turns no matter how large nbits is.
- */
- int pnfrac = nfrac;
- const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2;
- /* The +2 corresponds to the /4 in the denominator */
-
- do {
- unsigned int anfrac = min(pnfrac, pool_size/2);
- unsigned int add =
- ((pool_size - entropy_count)*anfrac*3) >> s;
-
- entropy_count += add;
- pnfrac -= anfrac;
- } while (unlikely(entropy_count < pool_size-2 && pnfrac));
- }
-
- if (WARN_ON(entropy_count < 0)) {
- pr_warn("negative entropy/overflow: pool %s count %d\n",
- r->name, entropy_count);
- entropy_count = 0;
- } else if (entropy_count > pool_size)
- entropy_count = pool_size;
- if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
- goto retry;
-
- if (has_initialized) {
- r->initialized = 1;
- kill_fasync(&fasync, SIGIO, POLL_IN);
- }
-
- trace_credit_entropy_bits(r->name, nbits,
- entropy_count >> ENTROPY_SHIFT, _RET_IP_);
-
- if (r == &input_pool) {
- int entropy_bits = entropy_count >> ENTROPY_SHIFT;
-
- if (crng_init < 2) {
- if (entropy_bits < 128)
- return;
- crng_reseed(&primary_crng, r);
- entropy_bits = ENTROPY_BITS(r);
- }
- }
-}
-
-static int credit_entropy_bits_safe(struct entropy_store *r, int nbits)
-{
- const int nbits_max = r->poolinfo->poolwords * 32;
-
- if (nbits < 0)
- return -EINVAL;
-
- /* Cap the value to avoid overflows */
- nbits = min(nbits, nbits_max);
-
- credit_entropy_bits(r, nbits);
- return 0;
-}
+// GKI: Keep this header to retain the original CRC that previously used the
+// random.h tracepoints.
+#include <linux/writeback.h>
/*********************************************************************
*
- * CRNG using CHACHA20
+ * Initialization and readiness waiting.
+ *
+ * Much of the RNG infrastructure is devoted to various dependencies
+ * being able to wait until the RNG has collected enough entropy and
+ * is ready for safe consumption.
*
*********************************************************************/
-#define CRNG_RESEED_INTERVAL (300*HZ)
-
+/*
+ * crng_init is protected by base_crng->lock, and only increases
+ * its value (from empty->early->ready).
+ */
+static enum {
+ CRNG_EMPTY = 0, /* Little to no entropy collected */
+ CRNG_EARLY = 1, /* At least POOL_EARLY_BITS collected */
+ CRNG_READY = 2 /* Fully initialized with POOL_READY_BITS collected */
+} crng_init __read_mostly = CRNG_EMPTY;
+#define crng_ready() (likely(crng_init >= CRNG_READY))
+/* Various types of waiters for crng_init->CRNG_READY transition. */
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
+static struct fasync_struct *fasync;
+static DEFINE_SPINLOCK(random_ready_chain_lock);
+static RAW_NOTIFIER_HEAD(random_ready_chain);
-#ifdef CONFIG_NUMA
-/*
- * Hack to deal with crazy userspace progams when they are all trying
- * to access /dev/urandom in parallel. The programs are almost
- * certainly doing something terribly wrong, but we'll work around
- * their brain damage.
- */
-static struct crng_state **crng_node_pool __read_mostly;
-#endif
-
-static void invalidate_batched_entropy(void);
-static void numa_crng_init(void);
-
-static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
-static int __init parse_trust_cpu(char *arg)
-{
- return kstrtobool(arg, &trust_cpu);
-}
-early_param("random.trust_cpu", parse_trust_cpu);
-
-static void crng_initialize(struct crng_state *crng)
-{
- int i;
- int arch_init = 1;
- unsigned long rv;
-
- memcpy(&crng->state[0], "expand 32-byte k", 16);
- if (crng == &primary_crng)
- _extract_entropy(&input_pool, &crng->state[4],
- sizeof(__u32) * 12, 0);
- else
- _get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
- for (i = 4; i < 16; i++) {
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv)) {
- rv = random_get_entropy();
- arch_init = 0;
- }
- crng->state[i] ^= rv;
- }
- if (trust_cpu && arch_init && crng == &primary_crng) {
- invalidate_batched_entropy();
- numa_crng_init();
- crng_init = 2;
- pr_notice("crng done (trusting CPU's manufacturer)\n");
- }
- crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
-}
-
-#ifdef CONFIG_NUMA
-static void do_numa_crng_init(struct work_struct *work)
-{
- int i;
- struct crng_state *crng;
- struct crng_state **pool;
-
- pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL);
- for_each_online_node(i) {
- crng = kmalloc_node(sizeof(struct crng_state),
- GFP_KERNEL | __GFP_NOFAIL, i);
- spin_lock_init(&crng->lock);
- crng_initialize(crng);
- pool[i] = crng;
- }
- /* pairs with READ_ONCE() in select_crng() */
- if (cmpxchg_release(&crng_node_pool, NULL, pool) != NULL) {
- for_each_node(i)
- kfree(pool[i]);
- kfree(pool);
- }
-}
-
-static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init);
-
-static void numa_crng_init(void)
-{
- schedule_work(&numa_crng_init_work);
-}
-
-static struct crng_state *select_crng(void)
-{
- struct crng_state **pool;
- int nid = numa_node_id();
-
- /* pairs with cmpxchg_release() in do_numa_crng_init() */
- pool = READ_ONCE(crng_node_pool);
- if (pool && pool[nid])
- return pool[nid];
-
- return &primary_crng;
-}
-#else
-static void numa_crng_init(void) {}
-
-static struct crng_state *select_crng(void)
-{
- return &primary_crng;
-}
-#endif
+/* Control how we warn userspace. */
+static struct ratelimit_state urandom_warning =
+ RATELIMIT_STATE_INIT_FLAGS("urandom_warning", HZ, 3, RATELIMIT_MSG_ON_RELEASE);
+static int ratelimit_disable __read_mostly =
+ IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM);
+module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
+MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
/*
- * crng_fast_load() can be called by code in the interrupt service
- * path. So we can't afford to dilly-dally.
+ * Returns whether or not the input pool has been seeded and thus guaranteed
+ * to supply cryptographically secure random numbers. This applies to: the
+ * /dev/urandom device, the get_random_bytes function, and the get_random_{u32,
+ * ,u64,int,long} family of functions.
+ *
+ * Returns: true if the input pool has been seeded.
+ * false if the input pool has not been seeded.
*/
-static int crng_fast_load(const char *cp, size_t len)
+bool rng_is_initialized(void)
+{
+ return crng_ready();
+}
+EXPORT_SYMBOL(rng_is_initialized);
+
+/* Used by wait_for_random_bytes(), and considered an entropy collector, below. */
+static void try_to_generate_entropy(void);
+
+/*
+ * Wait for the input pool to be seeded and thus guaranteed to supply
+ * cryptographically secure random numbers. This applies to: the /dev/urandom
+ * device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
+ * family of functions. Using any of these functions without first calling
+ * this function forfeits the guarantee of security.
+ *
+ * Returns: 0 if the input pool has been seeded.
+ * -ERESTARTSYS if the function was interrupted by a signal.
+ */
+int wait_for_random_bytes(void)
+{
+ while (!crng_ready()) {
+ int ret;
+
+ try_to_generate_entropy();
+ ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
+ if (ret)
+ return ret > 0 ? 0 : ret;
+ }
+ return 0;
+}
+EXPORT_SYMBOL(wait_for_random_bytes);
+
+/*
+ * Add a callback function that will be invoked when the input
+ * pool is initialised.
+ *
+ * returns: 0 if callback is successfully added
+ * -EALREADY if pool is already initialised (callback not called)
+ */
+int __cold register_random_ready_notifier(struct notifier_block *nb)
{
unsigned long flags;
- char *p;
+ int ret = -EALREADY;
- if (!spin_trylock_irqsave(&primary_crng.lock, flags))
- return 0;
- if (crng_init != 0) {
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- return 0;
- }
- p = (unsigned char *) &primary_crng.state[4];
- while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
- p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp;
- cp++; crng_init_cnt++; len--;
- }
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
- invalidate_batched_entropy();
- crng_init = 1;
- pr_notice("fast init done\n");
- }
- return 1;
+ if (crng_ready())
+ return ret;
+
+ spin_lock_irqsave(&random_ready_chain_lock, flags);
+ if (!crng_ready())
+ ret = raw_notifier_chain_register(&random_ready_chain, nb);
+ spin_unlock_irqrestore(&random_ready_chain_lock, flags);
+ return ret;
}
/*
- * crng_slow_load() is called by add_device_randomness, which has two
- * attributes. (1) We can't trust the buffer passed to it is
- * guaranteed to be unpredictable (so it might not have any entropy at
- * all), and (2) it doesn't have the performance constraints of
- * crng_fast_load().
- *
- * So we do something more comprehensive which is guaranteed to touch
- * all of the primary_crng's state, and which uses a LFSR with a
- * period of 255 as part of the mixing algorithm. Finally, we do
- * *not* advance crng_init_cnt since buffer we may get may be something
- * like a fixed DMI table (for example), which might very well be
- * unique to the machine, but is otherwise unvarying.
+ * Delete a previously registered readiness callback function.
*/
-static int crng_slow_load(const char *cp, size_t len)
+int __cold unregister_random_ready_notifier(struct notifier_block *nb)
{
- unsigned long flags;
- static unsigned char lfsr = 1;
- unsigned char tmp;
- unsigned i, max = CHACHA_KEY_SIZE;
- const char * src_buf = cp;
- char * dest_buf = (char *) &primary_crng.state[4];
+ unsigned long flags;
+ int ret;
- if (!spin_trylock_irqsave(&primary_crng.lock, flags))
- return 0;
- if (crng_init != 0) {
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- return 0;
- }
- if (len > max)
- max = len;
-
- for (i = 0; i < max ; i++) {
- tmp = lfsr;
- lfsr >>= 1;
- if (tmp & 1)
- lfsr ^= 0xE1;
- tmp = dest_buf[i % CHACHA_KEY_SIZE];
- dest_buf[i % CHACHA_KEY_SIZE] ^= src_buf[i % len] ^ lfsr;
- lfsr += (tmp << 3) | (tmp >> 5);
- }
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- return 1;
+ spin_lock_irqsave(&random_ready_chain_lock, flags);
+ ret = raw_notifier_chain_unregister(&random_ready_chain, nb);
+ spin_unlock_irqrestore(&random_ready_chain_lock, flags);
+ return ret;
}
-static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
+static void process_oldschool_random_ready_list(void);
+static void __cold process_random_ready_list(void)
{
- unsigned long flags;
- int i, num;
- union {
- __u8 block[CHACHA_BLOCK_SIZE];
- __u32 key[8];
- } buf;
+ unsigned long flags;
- if (r) {
- num = extract_entropy(r, &buf, 32, 16, 0);
- if (num == 0)
+ spin_lock_irqsave(&random_ready_chain_lock, flags);
+ raw_notifier_call_chain(&random_ready_chain, 0, NULL);
+ spin_unlock_irqrestore(&random_ready_chain_lock, flags);
+
+ process_oldschool_random_ready_list();
+}
+
+#define warn_unseeded_randomness() \
+ if (IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) && !crng_ready()) \
+ printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", \
+ __func__, (void *)_RET_IP_, crng_init)
+
+
+/*********************************************************************
+ *
+ * Fast key erasure RNG, the "crng".
+ *
+ * These functions expand entropy from the entropy extractor into
+ * long streams for external consumption using the "fast key erasure"
+ * RNG described at <https://blog.cr.yp.to/20170723-random.html>.
+ *
+ * There are a few exported interfaces for use by other drivers:
+ *
+ * void get_random_bytes(void *buf, size_t len)
+ * u32 get_random_u32()
+ * u64 get_random_u64()
+ * unsigned int get_random_int()
+ * unsigned long get_random_long()
+ *
+ * These interfaces will return the requested number of random bytes
+ * into the given buffer or as a return value. This is equivalent to
+ * a read from /dev/urandom. The u32, u64, int, and long family of
+ * functions may be higher performance for one-off random integers,
+ * because they do a bit of buffering and do not invoke reseeding
+ * until the buffer is emptied.
+ *
+ *********************************************************************/
+
+enum {
+ CRNG_RESEED_START_INTERVAL = HZ,
+ CRNG_RESEED_INTERVAL = 60 * HZ
+};
+
+static struct {
+ u8 key[CHACHA_KEY_SIZE] __aligned(__alignof__(long));
+ unsigned long birth;
+ unsigned long generation;
+ spinlock_t lock;
+} base_crng = {
+ .lock = __SPIN_LOCK_UNLOCKED(base_crng.lock)
+};
+
+struct crng {
+ u8 key[CHACHA_KEY_SIZE];
+ unsigned long generation;
+ local_lock_t lock;
+};
+
+static DEFINE_PER_CPU(struct crng, crngs) = {
+ .generation = ULONG_MAX,
+ .lock = INIT_LOCAL_LOCK(crngs.lock),
+};
+
+/* Used by crng_reseed() and crng_make_state() to extract a new seed from the input pool. */
+static void extract_entropy(void *buf, size_t len);
+
+/* This extracts a new crng key from the input pool. */
+static void crng_reseed(void)
+{
+ unsigned long flags;
+ unsigned long next_gen;
+ u8 key[CHACHA_KEY_SIZE];
+
+ extract_entropy(key, sizeof(key));
+
+ /*
+ * We copy the new key into the base_crng, overwriting the old one,
+ * and update the generation counter. We avoid hitting ULONG_MAX,
+ * because the per-cpu crngs are initialized to ULONG_MAX, so this
+ * forces new CPUs that come online to always initialize.
+ */
+ spin_lock_irqsave(&base_crng.lock, flags);
+ memcpy(base_crng.key, key, sizeof(base_crng.key));
+ next_gen = base_crng.generation + 1;
+ if (next_gen == ULONG_MAX)
+ ++next_gen;
+ WRITE_ONCE(base_crng.generation, next_gen);
+ WRITE_ONCE(base_crng.birth, jiffies);
+ if (!crng_ready())
+ crng_init = CRNG_READY;
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ memzero_explicit(key, sizeof(key));
+}
+
+/*
+ * This generates a ChaCha block using the provided key, and then
+ * immediately overwites that key with half the block. It returns
+ * the resultant ChaCha state to the user, along with the second
+ * half of the block containing 32 bytes of random data that may
+ * be used; random_data_len may not be greater than 32.
+ *
+ * The returned ChaCha state contains within it a copy of the old
+ * key value, at index 4, so the state should always be zeroed out
+ * immediately after using in order to maintain forward secrecy.
+ * If the state cannot be erased in a timely manner, then it is
+ * safer to set the random_data parameter to &chacha_state[4] so
+ * that this function overwrites it before returning.
+ */
+static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE],
+ u32 chacha_state[CHACHA_STATE_WORDS],
+ u8 *random_data, size_t random_data_len)
+{
+ u8 first_block[CHACHA_BLOCK_SIZE];
+
+ BUG_ON(random_data_len > 32);
+
+ chacha_init_consts(chacha_state);
+ memcpy(&chacha_state[4], key, CHACHA_KEY_SIZE);
+ memset(&chacha_state[12], 0, sizeof(u32) * 4);
+ chacha20_block(chacha_state, first_block);
+
+ memcpy(key, first_block, CHACHA_KEY_SIZE);
+ memcpy(random_data, first_block + CHACHA_KEY_SIZE, random_data_len);
+ memzero_explicit(first_block, sizeof(first_block));
+}
+
+/*
+ * Return whether the crng seed is considered to be sufficiently old
+ * that a reseeding is needed. This happens if the last reseeding
+ * was CRNG_RESEED_INTERVAL ago, or during early boot, at an interval
+ * proportional to the uptime.
+ */
+static bool crng_has_old_seed(void)
+{
+ static bool early_boot = true;
+ unsigned long interval = CRNG_RESEED_INTERVAL;
+
+ if (unlikely(READ_ONCE(early_boot))) {
+ time64_t uptime = ktime_get_seconds();
+ if (uptime >= CRNG_RESEED_INTERVAL / HZ * 2)
+ WRITE_ONCE(early_boot, false);
+ else
+ interval = max_t(unsigned int, CRNG_RESEED_START_INTERVAL,
+ (unsigned int)uptime / 2 * HZ);
+ }
+ return time_is_before_jiffies(READ_ONCE(base_crng.birth) + interval);
+}
+
+/*
+ * This function returns a ChaCha state that you may use for generating
+ * random data. It also returns up to 32 bytes on its own of random data
+ * that may be used; random_data_len may not be greater than 32.
+ */
+static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS],
+ u8 *random_data, size_t random_data_len)
+{
+ unsigned long flags;
+ struct crng *crng;
+
+ BUG_ON(random_data_len > 32);
+
+ /*
+ * For the fast path, we check whether we're ready, unlocked first, and
+ * then re-check once locked later. In the case where we're really not
+ * ready, we do fast key erasure with the base_crng directly, extracting
+ * when crng_init is CRNG_EMPTY.
+ */
+ if (!crng_ready()) {
+ bool ready;
+
+ spin_lock_irqsave(&base_crng.lock, flags);
+ ready = crng_ready();
+ if (!ready) {
+ if (crng_init == CRNG_EMPTY)
+ extract_entropy(base_crng.key, sizeof(base_crng.key));
+ crng_fast_key_erasure(base_crng.key, chacha_state,
+ random_data, random_data_len);
+ }
+ spin_unlock_irqrestore(&base_crng.lock, flags);
+ if (!ready)
return;
- } else {
- _extract_crng(&primary_crng, buf.block);
- _crng_backtrack_protect(&primary_crng, buf.block,
- CHACHA_KEY_SIZE);
}
- spin_lock_irqsave(&crng->lock, flags);
- for (i = 0; i < 8; i++) {
- unsigned long rv;
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv))
- rv = random_get_entropy();
- crng->state[i+4] ^= buf.key[i] ^ rv;
+
+ /*
+ * If the base_crng is old enough, we reseed, which in turn bumps the
+ * generation counter that we check below.
+ */
+ if (unlikely(crng_has_old_seed()))
+ crng_reseed();
+
+ local_lock_irqsave(&crngs.lock, flags);
+ crng = raw_cpu_ptr(&crngs);
+
+ /*
+ * If our per-cpu crng is older than the base_crng, then it means
+ * somebody reseeded the base_crng. In that case, we do fast key
+ * erasure on the base_crng, and use its output as the new key
+ * for our per-cpu crng. This brings us up to date with base_crng.
+ */
+ if (unlikely(crng->generation != READ_ONCE(base_crng.generation))) {
+ spin_lock(&base_crng.lock);
+ crng_fast_key_erasure(base_crng.key, chacha_state,
+ crng->key, sizeof(crng->key));
+ crng->generation = base_crng.generation;
+ spin_unlock(&base_crng.lock);
}
- memzero_explicit(&buf, sizeof(buf));
- WRITE_ONCE(crng->init_time, jiffies);
- spin_unlock_irqrestore(&crng->lock, flags);
- if (crng == &primary_crng && crng_init < 2) {
- invalidate_batched_entropy();
- numa_crng_init();
- crng_init = 2;
+
+ /*
+ * Finally, when we've made it this far, our per-cpu crng has an up
+ * to date key, and we can do fast key erasure with it to produce
+ * some random data and a ChaCha state for the caller. All other
+ * branches of this function are "unlikely", so most of the time we
+ * should wind up here immediately.
+ */
+ crng_fast_key_erasure(crng->key, chacha_state, random_data, random_data_len);
+ local_unlock_irqrestore(&crngs.lock, flags);
+}
+
+static void _get_random_bytes(void *buf, size_t len)
+{
+ u32 chacha_state[CHACHA_STATE_WORDS];
+ u8 tmp[CHACHA_BLOCK_SIZE];
+ size_t first_block_len;
+
+ if (!len)
+ return;
+
+ first_block_len = min_t(size_t, 32, len);
+ crng_make_state(chacha_state, buf, first_block_len);
+ len -= first_block_len;
+ buf += first_block_len;
+
+ while (len) {
+ if (len < CHACHA_BLOCK_SIZE) {
+ chacha20_block(chacha_state, tmp);
+ memcpy(buf, tmp, len);
+ memzero_explicit(tmp, sizeof(tmp));
+ break;
+ }
+
+ chacha20_block(chacha_state, buf);
+ if (unlikely(chacha_state[12] == 0))
+ ++chacha_state[13];
+ len -= CHACHA_BLOCK_SIZE;
+ buf += CHACHA_BLOCK_SIZE;
+ }
+
+ memzero_explicit(chacha_state, sizeof(chacha_state));
+}
+
+/*
+ * This function is the exported kernel interface. It returns some
+ * number of good random numbers, suitable for key generation, seeding
+ * TCP sequence numbers, etc. It does not rely on the hardware random
+ * number generator. For random bytes direct from the hardware RNG
+ * (when available), use get_random_bytes_arch(). In order to ensure
+ * that the randomness provided by this function is okay, the function
+ * wait_for_random_bytes() should be called and return 0 at least once
+ * at any point prior.
+ */
+void get_random_bytes(void *buf, int len)
+{
+ warn_unseeded_randomness();
+ _get_random_bytes(buf, len);
+}
+EXPORT_SYMBOL(get_random_bytes);
+
+static ssize_t get_random_bytes_user(struct iov_iter *iter)
+{
+ u32 chacha_state[CHACHA_STATE_WORDS];
+ u8 block[CHACHA_BLOCK_SIZE];
+ size_t ret = 0, copied;
+
+ if (unlikely(!iov_iter_count(iter)))
+ return 0;
+
+ /*
+ * Immediately overwrite the ChaCha key at index 4 with random
+ * bytes, in case userspace causes copy_to_iter() below to sleep
+ * forever, so that we still retain forward secrecy in that case.
+ */
+ crng_make_state(chacha_state, (u8 *)&chacha_state[4], CHACHA_KEY_SIZE);
+ /*
+ * However, if we're doing a read of len <= 32, we don't need to
+ * use chacha_state after, so we can simply return those bytes to
+ * the user directly.
+ */
+ if (iov_iter_count(iter) <= CHACHA_KEY_SIZE) {
+ ret = copy_to_iter(&chacha_state[4], CHACHA_KEY_SIZE, iter);
+ goto out_zero_chacha;
+ }
+
+ for (;;) {
+ chacha20_block(chacha_state, block);
+ if (unlikely(chacha_state[12] == 0))
+ ++chacha_state[13];
+
+ copied = copy_to_iter(block, sizeof(block), iter);
+ ret += copied;
+ if (!iov_iter_count(iter) || copied != sizeof(block))
+ break;
+
+ BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0);
+ if (ret % PAGE_SIZE == 0) {
+ if (signal_pending(current))
+ break;
+ cond_resched();
+ }
+ }
+
+ memzero_explicit(block, sizeof(block));
+out_zero_chacha:
+ memzero_explicit(chacha_state, sizeof(chacha_state));
+ return ret ? ret : -EFAULT;
+}
+
+/*
+ * Batched entropy returns random integers. The quality of the random
+ * number is good as /dev/urandom. In order to ensure that the randomness
+ * provided by this function is okay, the function wait_for_random_bytes()
+ * should be called and return 0 at least once at any point prior.
+ */
+
+#define DEFINE_BATCHED_ENTROPY(type) \
+struct batch_ ##type { \
+ /* \
+ * We make this 1.5x a ChaCha block, so that we get the \
+ * remaining 32 bytes from fast key erasure, plus one full \
+ * block from the detached ChaCha state. We can increase \
+ * the size of this later if needed so long as we keep the \
+ * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE. \
+ */ \
+ type entropy[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(type))]; \
+ local_lock_t lock; \
+ unsigned long generation; \
+ unsigned int position; \
+}; \
+ \
+static DEFINE_PER_CPU(struct batch_ ##type, batched_entropy_ ##type) = { \
+ .lock = INIT_LOCAL_LOCK(batched_entropy_ ##type.lock), \
+ .position = UINT_MAX \
+}; \
+ \
+type get_random_ ##type(void) \
+{ \
+ type ret; \
+ unsigned long flags; \
+ struct batch_ ##type *batch; \
+ unsigned long next_gen; \
+ \
+ warn_unseeded_randomness(); \
+ \
+ if (!crng_ready()) { \
+ _get_random_bytes(&ret, sizeof(ret)); \
+ return ret; \
+ } \
+ \
+ local_lock_irqsave(&batched_entropy_ ##type.lock, flags); \
+ batch = raw_cpu_ptr(&batched_entropy_##type); \
+ \
+ next_gen = READ_ONCE(base_crng.generation); \
+ if (batch->position >= ARRAY_SIZE(batch->entropy) || \
+ next_gen != batch->generation) { \
+ _get_random_bytes(batch->entropy, sizeof(batch->entropy)); \
+ batch->position = 0; \
+ batch->generation = next_gen; \
+ } \
+ \
+ ret = batch->entropy[batch->position]; \
+ batch->entropy[batch->position] = 0; \
+ ++batch->position; \
+ local_unlock_irqrestore(&batched_entropy_ ##type.lock, flags); \
+ return ret; \
+} \
+EXPORT_SYMBOL(get_random_ ##type);
+
+DEFINE_BATCHED_ENTROPY(u64)
+DEFINE_BATCHED_ENTROPY(u32)
+
+#ifdef CONFIG_SMP
+/*
+ * This function is called when the CPU is coming up, with entry
+ * CPUHP_RANDOM_PREPARE, which comes before CPUHP_WORKQUEUE_PREP.
+ */
+int __cold random_prepare_cpu(unsigned int cpu)
+{
+ /*
+ * When the cpu comes back online, immediately invalidate both
+ * the per-cpu crng and all batches, so that we serve fresh
+ * randomness.
+ */
+ per_cpu_ptr(&crngs, cpu)->generation = ULONG_MAX;
+ per_cpu_ptr(&batched_entropy_u32, cpu)->position = UINT_MAX;
+ per_cpu_ptr(&batched_entropy_u64, cpu)->position = UINT_MAX;
+ return 0;
+}
+#endif
+
+/*
+ * This function will use the architecture-specific hardware random
+ * number generator if it is available. It is not recommended for
+ * use. Use get_random_bytes() instead. It returns the number of
+ * bytes filled in.
+ */
+int __must_check get_random_bytes_arch(void *buf, int len)
+{
+ size_t left = len;
+ u8 *p = buf;
+
+ while (left) {
+ unsigned long v;
+ size_t block_len = min_t(size_t, left, sizeof(unsigned long));
+
+ if (!arch_get_random_long(&v))
+ break;
+
+ memcpy(p, &v, block_len);
+ p += block_len;
+ left -= block_len;
+ }
+
+ return len - left;
+}
+EXPORT_SYMBOL(get_random_bytes_arch);
+
+
+/**********************************************************************
+ *
+ * Entropy accumulation and extraction routines.
+ *
+ * Callers may add entropy via:
+ *
+ * static void mix_pool_bytes(const void *buf, size_t len)
+ *
+ * After which, if added entropy should be credited:
+ *
+ * static void credit_init_bits(size_t bits)
+ *
+ * Finally, extract entropy via:
+ *
+ * static void extract_entropy(void *buf, size_t len)
+ *
+ **********************************************************************/
+
+enum {
+ POOL_BITS = BLAKE2S_HASH_SIZE * 8,
+ POOL_READY_BITS = POOL_BITS, /* When crng_init->CRNG_READY */
+ POOL_EARLY_BITS = POOL_READY_BITS / 2 /* When crng_init->CRNG_EARLY */
+};
+
+static struct {
+ struct blake2s_state hash;
+ spinlock_t lock;
+ unsigned int init_bits;
+} input_pool = {
+ .hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE),
+ BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4,
+ BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 },
+ .hash.outlen = BLAKE2S_HASH_SIZE,
+ .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
+};
+
+static void _mix_pool_bytes(const void *buf, size_t len)
+{
+ blake2s_update(&input_pool.hash, buf, len);
+}
+
+/*
+ * This function adds bytes into the input pool. It does not
+ * update the initialization bit counter; the caller should call
+ * credit_init_bits if this is appropriate.
+ */
+static void mix_pool_bytes(const void *buf, size_t len)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&input_pool.lock, flags);
+ _mix_pool_bytes(buf, len);
+ spin_unlock_irqrestore(&input_pool.lock, flags);
+}
+
+/*
+ * This is an HKDF-like construction for using the hashed collected entropy
+ * as a PRF key, that's then expanded block-by-block.
+ */
+static void extract_entropy(void *buf, size_t len)
+{
+ unsigned long flags;
+ u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
+ struct {
+ unsigned long rdseed[32 / sizeof(long)];
+ size_t counter;
+ } block;
+ size_t i;
+
+ for (i = 0; i < ARRAY_SIZE(block.rdseed); ++i) {
+ if (!arch_get_random_seed_long(&block.rdseed[i]) &&
+ !arch_get_random_long(&block.rdseed[i]))
+ block.rdseed[i] = random_get_entropy();
+ }
+
+ spin_lock_irqsave(&input_pool.lock, flags);
+
+ /* seed = HASHPRF(last_key, entropy_input) */
+ blake2s_final(&input_pool.hash, seed);
+
+ /* next_key = HASHPRF(seed, RDSEED || 0) */
+ block.counter = 0;
+ blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed));
+ blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key));
+
+ spin_unlock_irqrestore(&input_pool.lock, flags);
+ memzero_explicit(next_key, sizeof(next_key));
+
+ while (len) {
+ i = min_t(size_t, len, BLAKE2S_HASH_SIZE);
+ /* output = HASHPRF(seed, RDSEED || ++counter) */
+ ++block.counter;
+ blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed));
+ len -= i;
+ buf += i;
+ }
+
+ memzero_explicit(seed, sizeof(seed));
+ memzero_explicit(&block, sizeof(block));
+}
+
+#define credit_init_bits(bits) if (!crng_ready()) _credit_init_bits(bits)
+
+static void __cold _credit_init_bits(size_t bits)
+{
+ unsigned int new, orig, add;
+ unsigned long flags;
+
+ if (!bits)
+ return;
+
+ add = min_t(size_t, bits, POOL_BITS);
+
+ do {
+ orig = READ_ONCE(input_pool.init_bits);
+ new = min_t(unsigned int, POOL_BITS, orig + add);
+ } while (cmpxchg(&input_pool.init_bits, orig, new) != orig);
+
+ if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
+ crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
process_random_ready_list();
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
pr_notice("crng init done\n");
- if (unseeded_warning.missed) {
- pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
- unseeded_warning.missed);
- unseeded_warning.missed = 0;
- }
- if (urandom_warning.missed) {
+ if (urandom_warning.missed)
pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
urandom_warning.missed);
- urandom_warning.missed = 0;
+ } else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
+ spin_lock_irqsave(&base_crng.lock, flags);
+ /* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */
+ if (crng_init == CRNG_EMPTY) {
+ extract_entropy(base_crng.key, sizeof(base_crng.key));
+ crng_init = CRNG_EARLY;
}
+ spin_unlock_irqrestore(&base_crng.lock, flags);
}
}
-static void _extract_crng(struct crng_state *crng,
- __u8 out[CHACHA_BLOCK_SIZE])
-{
- unsigned long v, flags, init_time;
- if (crng_ready()) {
- init_time = READ_ONCE(crng->init_time);
- if (time_after(READ_ONCE(crng_global_init_time), init_time) ||
- time_after(jiffies, init_time + CRNG_RESEED_INTERVAL))
- crng_reseed(crng, crng == &primary_crng ?
- &input_pool : NULL);
- }
- spin_lock_irqsave(&crng->lock, flags);
- if (arch_get_random_long(&v))
- crng->state[14] ^= v;
- chacha20_block(&crng->state[0], out);
- if (crng->state[12] == 0)
- crng->state[13]++;
- spin_unlock_irqrestore(&crng->lock, flags);
-}
+/**********************************************************************
+ *
+ * Entropy collection routines.
+ *
+ * The following exported functions are used for pushing entropy into
+ * the above entropy accumulation routines:
+ *
+ * void add_device_randomness(const void *buf, size_t len);
+ * void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy);
+ * void add_bootloader_randomness(const void *buf, size_t len);
+ * void add_interrupt_randomness(int irq);
+ * void add_input_randomness(unsigned int type, unsigned int code, unsigned int value);
+ * void add_disk_randomness(struct gendisk *disk);
+ *
+ * add_device_randomness() adds data to the input pool that
+ * is likely to differ between two devices (or possibly even per boot).
+ * This would be things like MAC addresses or serial numbers, or the
+ * read-out of the RTC. This does *not* credit any actual entropy to
+ * the pool, but it initializes the pool to different values for devices
+ * that might otherwise be identical and have very little entropy
+ * available to them (particularly common in the embedded world).
+ *
+ * add_hwgenerator_randomness() is for true hardware RNGs, and will credit
+ * entropy as specified by the caller. If the entropy pool is full it will
+ * block until more entropy is needed.
+ *
+ * add_bootloader_randomness() is called by bootloader drivers, such as EFI
+ * and device tree, and credits its input depending on whether or not the
+ * configuration option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
+ *
+ * add_interrupt_randomness() uses the interrupt timing as random
+ * inputs to the entropy pool. Using the cycle counters and the irq source
+ * as inputs, it feeds the input pool roughly once a second or after 64
+ * interrupts, crediting 1 bit of entropy for whichever comes first.
+ *
+ * add_input_randomness() uses the input layer interrupt timing, as well
+ * as the event type information from the hardware.
+ *
+ * add_disk_randomness() uses what amounts to the seek time of block
+ * layer request events, on a per-disk_devt basis, as input to the
+ * entropy pool. Note that high-speed solid state drives with very low
+ * seek times do not make for good sources of entropy, as their seek
+ * times are usually fairly consistent.
+ *
+ * The last two routines try to estimate how many bits of entropy
+ * to credit. They do this by keeping track of the first and second
+ * order deltas of the event timings.
+ *
+ **********************************************************************/
-static void extract_crng(__u8 out[CHACHA_BLOCK_SIZE])
+static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
+static bool trust_bootloader __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER);
+static int __init parse_trust_cpu(char *arg)
{
- _extract_crng(select_crng(), out);
+ return kstrtobool(arg, &trust_cpu);
}
+static int __init parse_trust_bootloader(char *arg)
+{
+ return kstrtobool(arg, &trust_bootloader);
+}
+early_param("random.trust_cpu", parse_trust_cpu);
+early_param("random.trust_bootloader", parse_trust_bootloader);
/*
- * Use the leftover bytes from the CRNG block output (if there is
- * enough) to mutate the CRNG key to provide backtracking protection.
+ * The first collection of entropy occurs at system boot while interrupts
+ * are still turned off. Here we push in latent entropy, RDSEED, a timestamp,
+ * utsname(), and the command line. Depending on the above configuration knob,
+ * RDSEED may be considered sufficient for initialization. Note that much
+ * earlier setup may already have pushed entropy into the input pool by the
+ * time we get here.
*/
-static void _crng_backtrack_protect(struct crng_state *crng,
- __u8 tmp[CHACHA_BLOCK_SIZE], int used)
+int __init random_init(const char *command_line)
{
- unsigned long flags;
- __u32 *s, *d;
- int i;
+ ktime_t now = ktime_get_real();
+ unsigned int i, arch_bytes;
+ unsigned long entropy;
- used = round_up(used, sizeof(__u32));
- if (used + CHACHA_KEY_SIZE > CHACHA_BLOCK_SIZE) {
- extract_crng(tmp);
- used = 0;
- }
- spin_lock_irqsave(&crng->lock, flags);
- s = (__u32 *) &tmp[used];
- d = &crng->state[4];
- for (i=0; i < 8; i++)
- *d++ ^= *s++;
- spin_unlock_irqrestore(&crng->lock, flags);
-}
+#if defined(LATENT_ENTROPY_PLUGIN)
+ static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy;
+ _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));
+#endif
-static void crng_backtrack_protect(__u8 tmp[CHACHA_BLOCK_SIZE], int used)
-{
- _crng_backtrack_protect(select_crng(), tmp, used);
-}
-
-static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
-{
- ssize_t ret = 0, i = CHACHA_BLOCK_SIZE;
- __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
- int large_request = (nbytes > 256);
-
- while (nbytes) {
- if (large_request && need_resched()) {
- if (signal_pending(current)) {
- if (ret == 0)
- ret = -ERESTARTSYS;
- break;
- }
- schedule();
+ for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE;
+ i < BLAKE2S_BLOCK_SIZE; i += sizeof(entropy)) {
+ if (!arch_get_random_seed_long_early(&entropy) &&
+ !arch_get_random_long_early(&entropy)) {
+ entropy = random_get_entropy();
+ arch_bytes -= sizeof(entropy);
}
-
- extract_crng(tmp);
- i = min_t(int, nbytes, CHACHA_BLOCK_SIZE);
- if (copy_to_user(buf, tmp, i)) {
- ret = -EFAULT;
- break;
- }
-
- nbytes -= i;
- buf += i;
- ret += i;
+ _mix_pool_bytes(&entropy, sizeof(entropy));
}
- crng_backtrack_protect(tmp, i);
+ _mix_pool_bytes(&now, sizeof(now));
+ _mix_pool_bytes(utsname(), sizeof(*(utsname())));
+ _mix_pool_bytes(command_line, strlen(command_line));
+ add_latent_entropy();
- /* Wipe data just written to memory */
- memzero_explicit(tmp, sizeof(tmp));
+ if (crng_ready())
+ crng_reseed();
+ else if (trust_cpu)
+ credit_init_bits(arch_bytes * 8);
- return ret;
+ return 0;
}
-
-
-/*********************************************************************
- *
- * Entropy input management
- *
- *********************************************************************/
-
-/* There is one of these per entropy source */
-struct timer_rand_state {
- cycles_t last_time;
- long last_delta, last_delta2;
-};
-
-#define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
/*
* Add device- or boot-specific data to the input pool to help
@@ -1098,57 +858,212 @@
* the entropy pool having similar initial state across largely
* identical devices.
*/
-void add_device_randomness(const void *buf, unsigned int size)
+void add_device_randomness(const void *buf, unsigned int len)
{
- unsigned long time = random_get_entropy() ^ jiffies;
+ unsigned long entropy = random_get_entropy();
unsigned long flags;
- if (!crng_ready() && size)
- crng_slow_load(buf, size);
-
- trace_add_device_randomness(size, _RET_IP_);
spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(&input_pool, buf, size);
- _mix_pool_bytes(&input_pool, &time, sizeof(time));
+ _mix_pool_bytes(&entropy, sizeof(entropy));
+ _mix_pool_bytes(buf, len);
spin_unlock_irqrestore(&input_pool.lock, flags);
}
EXPORT_SYMBOL(add_device_randomness);
-static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE;
+/*
+ * Interface for in-kernel drivers of true hardware RNGs.
+ * Those devices may produce endless random bits and will be throttled
+ * when our pool is full.
+ */
+void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy)
+{
+ mix_pool_bytes(buf, len);
+ credit_init_bits(entropy);
+
+ /*
+ * Throttle writing to once every CRNG_RESEED_INTERVAL, unless
+ * we're not yet initialized.
+ */
+ if (!kthread_should_stop() && crng_ready())
+ schedule_timeout_interruptible(CRNG_RESEED_INTERVAL);
+}
+EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
+
+/*
+ * Handle random seed passed by bootloader, and credit it if
+ * CONFIG_RANDOM_TRUST_BOOTLOADER is set.
+ */
+void __cold add_bootloader_randomness(const void *buf, size_t len)
+{
+ mix_pool_bytes(buf, len);
+ if (trust_bootloader)
+ credit_init_bits(len * 8);
+}
+EXPORT_SYMBOL_GPL(add_bootloader_randomness);
+
+struct fast_pool {
+ unsigned long pool[4];
+ unsigned long last;
+ unsigned int count;
+ struct timer_list mix;
+};
+
+static void mix_interrupt_randomness(struct timer_list *work);
+
+static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {
+#ifdef CONFIG_64BIT
+#define FASTMIX_PERM SIPHASH_PERMUTATION
+ .pool = { SIPHASH_CONST_0, SIPHASH_CONST_1, SIPHASH_CONST_2, SIPHASH_CONST_3 },
+#else
+#define FASTMIX_PERM HSIPHASH_PERMUTATION
+ .pool = { HSIPHASH_CONST_0, HSIPHASH_CONST_1, HSIPHASH_CONST_2, HSIPHASH_CONST_3 },
+#endif
+ .mix = __TIMER_INITIALIZER(mix_interrupt_randomness, 0)
+};
+
+/*
+ * This is [Half]SipHash-1-x, starting from an empty key. Because
+ * the key is fixed, it assumes that its inputs are non-malicious,
+ * and therefore this has no security on its own. s represents the
+ * four-word SipHash state, while v represents a two-word input.
+ */
+static void fast_mix(unsigned long s[4], unsigned long v1, unsigned long v2)
+{
+ s[3] ^= v1;
+ FASTMIX_PERM(s[0], s[1], s[2], s[3]);
+ s[0] ^= v1;
+ s[3] ^= v2;
+ FASTMIX_PERM(s[0], s[1], s[2], s[3]);
+ s[0] ^= v2;
+}
+
+#ifdef CONFIG_SMP
+/*
+ * This function is called when the CPU has just come online, with
+ * entry CPUHP_AP_RANDOM_ONLINE, just after CPUHP_AP_WORKQUEUE_ONLINE.
+ */
+int __cold random_online_cpu(unsigned int cpu)
+{
+ /*
+ * During CPU shutdown and before CPU onlining, add_interrupt_
+ * randomness() may schedule mix_interrupt_randomness(), and
+ * set the MIX_INFLIGHT flag. However, because the worker can
+ * be scheduled on a different CPU during this period, that
+ * flag will never be cleared. For that reason, we zero out
+ * the flag here, which runs just after workqueues are onlined
+ * for the CPU again. This also has the effect of setting the
+ * irq randomness count to zero so that new accumulated irqs
+ * are fresh.
+ */
+ per_cpu_ptr(&irq_randomness, cpu)->count = 0;
+ return 0;
+}
+#endif
+
+static void mix_interrupt_randomness(struct timer_list *work)
+{
+ struct fast_pool *fast_pool = container_of(work, struct fast_pool, mix);
+ /*
+ * The size of the copied stack pool is explicitly 2 longs so that we
+ * only ever ingest half of the siphash output each time, retaining
+ * the other half as the next "key" that carries over. The entropy is
+ * supposed to be sufficiently dispersed between bits so on average
+ * we don't wind up "losing" some.
+ */
+ unsigned long pool[2];
+ unsigned int count;
+
+ /* Check to see if we're running on the wrong CPU due to hotplug. */
+ local_irq_disable();
+ if (fast_pool != this_cpu_ptr(&irq_randomness)) {
+ local_irq_enable();
+ return;
+ }
+
+ /*
+ * Copy the pool to the stack so that the mixer always has a
+ * consistent view, before we reenable irqs again.
+ */
+ memcpy(pool, fast_pool->pool, sizeof(pool));
+ count = fast_pool->count;
+ fast_pool->count = 0;
+ fast_pool->last = jiffies;
+ local_irq_enable();
+
+ mix_pool_bytes(pool, sizeof(pool));
+ credit_init_bits(clamp_t(unsigned int, (count & U16_MAX) / 64, 1, sizeof(pool) * 8));
+
+ memzero_explicit(pool, sizeof(pool));
+}
+
+void add_interrupt_randomness(int irq)
+{
+ enum { MIX_INFLIGHT = 1U << 31 };
+ unsigned long entropy = random_get_entropy();
+ struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
+ struct pt_regs *regs = get_irq_regs();
+ unsigned int new_count;
+
+ fast_mix(fast_pool->pool, entropy,
+ (regs ? instruction_pointer(regs) : _RET_IP_) ^ swab(irq));
+ new_count = ++fast_pool->count;
+
+ if (new_count & MIX_INFLIGHT)
+ return;
+
+ if (new_count < 1024 && !time_is_before_jiffies(fast_pool->last + HZ))
+ return;
+
+ fast_pool->count |= MIX_INFLIGHT;
+ if (!timer_pending(&fast_pool->mix)) {
+ fast_pool->mix.expires = jiffies;
+ add_timer_on(&fast_pool->mix, raw_smp_processor_id());
+ }
+}
+EXPORT_SYMBOL_GPL(add_interrupt_randomness);
+
+/* There is one of these per entropy source */
+struct timer_rand_state {
+ unsigned long last_time;
+ long last_delta, last_delta2;
+};
/*
* This function adds entropy to the entropy "pool" by using timing
- * delays. It uses the timer_rand_state structure to make an estimate
- * of how many bits of entropy this call has added to the pool.
- *
- * The number "num" is also added to the pool - it should somehow describe
- * the type of event which just happened. This is currently 0-255 for
- * keyboard scan codes, and 256 upwards for interrupts.
- *
+ * delays. It uses the timer_rand_state structure to make an estimate
+ * of how many bits of entropy this call has added to the pool. The
+ * value "num" is also added to the pool; it should somehow describe
+ * the type of event that just happened.
*/
-static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
+static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
{
- struct entropy_store *r;
- struct {
- long jiffies;
- unsigned cycles;
- unsigned num;
- } sample;
+ unsigned long entropy = random_get_entropy(), now = jiffies, flags;
long delta, delta2, delta3;
+ unsigned int bits;
- sample.jiffies = jiffies;
- sample.cycles = random_get_entropy();
- sample.num = num;
- r = &input_pool;
- mix_pool_bytes(r, &sample, sizeof(sample));
+ /*
+ * If we're in a hard IRQ, add_interrupt_randomness() will be called
+ * sometime after, so mix into the fast pool.
+ */
+ if (in_irq()) {
+ fast_mix(this_cpu_ptr(&irq_randomness)->pool, entropy, num);
+ } else {
+ spin_lock_irqsave(&input_pool.lock, flags);
+ _mix_pool_bytes(&entropy, sizeof(entropy));
+ _mix_pool_bytes(&num, sizeof(num));
+ spin_unlock_irqrestore(&input_pool.lock, flags);
+ }
+
+ if (crng_ready())
+ return;
/*
* Calculate number of bits of randomness we probably added.
* We take into account the first, second and third-order deltas
* in order to make our estimate.
*/
- delta = sample.jiffies - READ_ONCE(state->last_time);
- WRITE_ONCE(state->last_time, sample.jiffies);
+ delta = now - READ_ONCE(state->last_time);
+ WRITE_ONCE(state->last_time, now);
delta2 = delta - READ_ONCE(state->last_delta);
WRITE_ONCE(state->last_delta, delta);
@@ -1168,390 +1083,64 @@
delta = delta3;
/*
- * delta is now minimum absolute delta.
- * Round down by 1 bit on general principles,
- * and limit entropy estimate to 12 bits.
+ * delta is now minimum absolute delta. Round down by 1 bit
+ * on general principles, and limit entropy estimate to 11 bits.
*/
- credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
+ bits = min(fls(delta >> 1), 11);
+
+ /*
+ * As mentioned above, if we're in a hard IRQ, add_interrupt_randomness()
+ * will run after this, which uses a different crediting scheme of 1 bit
+ * per every 64 interrupts. In order to let that function do accounting
+ * close to the one in this function, we credit a full 64/64 bit per bit,
+ * and then subtract one to account for the extra one added.
+ */
+ if (in_irq())
+ this_cpu_ptr(&irq_randomness)->count += max(1u, bits * 64) - 1;
+ else
+ _credit_init_bits(bits);
}
-void add_input_randomness(unsigned int type, unsigned int code,
- unsigned int value)
+void add_input_randomness(unsigned int type, unsigned int code, unsigned int value)
{
static unsigned char last_value;
+ static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES };
- /* ignore autorepeat and the like */
+ /* Ignore autorepeat and the like. */
if (value == last_value)
return;
last_value = value;
add_timer_randomness(&input_timer_state,
(type << 4) ^ code ^ (code >> 4) ^ value);
- trace_add_input_randomness(ENTROPY_BITS(&input_pool));
}
EXPORT_SYMBOL_GPL(add_input_randomness);
-
-static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
-
-#ifdef ADD_INTERRUPT_BENCH
-static unsigned long avg_cycles, avg_deviation;
-
-#define AVG_SHIFT 8 /* Exponential average factor k=1/256 */
-#define FIXED_1_2 (1 << (AVG_SHIFT-1))
-
-static void add_interrupt_bench(cycles_t start)
-{
- long delta = random_get_entropy() - start;
-
- /* Use a weighted moving average */
- delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT);
- avg_cycles += delta;
- /* And average deviation */
- delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT);
- avg_deviation += delta;
-}
-#else
-#define add_interrupt_bench(x)
-#endif
-
-static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
-{
- __u32 *ptr = (__u32 *) regs;
- unsigned int idx;
-
- if (regs == NULL)
- return 0;
- idx = READ_ONCE(f->reg_idx);
- if (idx >= sizeof(struct pt_regs) / sizeof(__u32))
- idx = 0;
- ptr += idx++;
- WRITE_ONCE(f->reg_idx, idx);
- return *ptr;
-}
-
-void add_interrupt_randomness(int irq, int irq_flags)
-{
- struct entropy_store *r;
- struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
- struct pt_regs *regs = get_irq_regs();
- unsigned long now = jiffies;
- cycles_t cycles = random_get_entropy();
- __u32 c_high, j_high;
- __u64 ip;
- unsigned long seed;
- int credit = 0;
-
- if (cycles == 0)
- cycles = get_reg(fast_pool, regs);
- c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
- j_high = (sizeof(now) > 4) ? now >> 32 : 0;
- fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
- fast_pool->pool[1] ^= now ^ c_high;
- ip = regs ? instruction_pointer(regs) : _RET_IP_;
- fast_pool->pool[2] ^= ip;
- fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
- get_reg(fast_pool, regs);
-
- fast_mix(fast_pool);
- add_interrupt_bench(cycles);
-
- if (unlikely(crng_init == 0)) {
- if ((fast_pool->count >= 64) &&
- crng_fast_load((char *) fast_pool->pool,
- sizeof(fast_pool->pool))) {
- fast_pool->count = 0;
- fast_pool->last = now;
- }
- return;
- }
-
- if ((fast_pool->count < 64) &&
- !time_after(now, fast_pool->last + HZ))
- return;
-
- r = &input_pool;
- if (!spin_trylock(&r->lock))
- return;
-
- fast_pool->last = now;
- __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
-
- /*
- * If we have architectural seed generator, produce a seed and
- * add it to the pool. For the sake of paranoia don't let the
- * architectural seed generator dominate the input from the
- * interrupt noise.
- */
- if (arch_get_random_seed_long(&seed)) {
- __mix_pool_bytes(r, &seed, sizeof(seed));
- credit = 1;
- }
- spin_unlock(&r->lock);
-
- fast_pool->count = 0;
-
- /* award one bit for the contents of the fast pool */
- credit_entropy_bits(r, credit + 1);
-}
-EXPORT_SYMBOL_GPL(add_interrupt_randomness);
#ifdef CONFIG_BLOCK
void add_disk_randomness(struct gendisk *disk)
{
if (!disk || !disk->random)
return;
- /* first major is 1, so we get >= 0x200 here */
+ /* First major is 1, so we get >= 0x200 here. */
add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
- trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool));
}
EXPORT_SYMBOL_GPL(add_disk_randomness);
-#endif
-/*********************************************************************
- *
- * Entropy extraction routines
- *
- *********************************************************************/
-
-/*
- * This function decides how many bytes to actually take from the
- * given pool, and also debits the entropy count accordingly.
- */
-static size_t account(struct entropy_store *r, size_t nbytes, int min,
- int reserved)
+void __cold rand_initialize_disk(struct gendisk *disk)
{
- int entropy_count, orig, have_bytes;
- size_t ibytes, nfrac;
-
- BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
-
- /* Can we pull enough? */
-retry:
- entropy_count = orig = READ_ONCE(r->entropy_count);
- ibytes = nbytes;
- /* never pull more than available */
- have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
-
- if ((have_bytes -= reserved) < 0)
- have_bytes = 0;
- ibytes = min_t(size_t, ibytes, have_bytes);
- if (ibytes < min)
- ibytes = 0;
-
- if (WARN_ON(entropy_count < 0)) {
- pr_warn("negative entropy count: pool %s count %d\n",
- r->name, entropy_count);
- entropy_count = 0;
- }
- nfrac = ibytes << (ENTROPY_SHIFT + 3);
- if ((size_t) entropy_count > nfrac)
- entropy_count -= nfrac;
- else
- entropy_count = 0;
-
- if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
- goto retry;
-
- trace_debit_entropy(r->name, 8 * ibytes);
- if (ibytes && ENTROPY_BITS(r) < random_write_wakeup_bits) {
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- }
-
- return ibytes;
-}
-
-/*
- * This function does the actual extraction for extract_entropy and
- * extract_entropy_user.
- *
- * Note: we assume that .poolwords is a multiple of 16 words.
- */
-static void extract_buf(struct entropy_store *r, __u8 *out)
-{
- int i;
- union {
- __u32 w[5];
- unsigned long l[LONGS(20)];
- } hash;
- __u32 workspace[SHA_WORKSPACE_WORDS];
- unsigned long flags;
+ struct timer_rand_state *state;
/*
- * If we have an architectural hardware random number
- * generator, use it for SHA's initial vector
+ * If kzalloc returns null, we just won't use that entropy
+ * source.
*/
- sha_init(hash.w);
- for (i = 0; i < LONGS(20); i++) {
- unsigned long v;
- if (!arch_get_random_long(&v))
- break;
- hash.l[i] = v;
+ state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
+ if (state) {
+ state->last_time = INITIAL_JIFFIES;
+ disk->random = state;
}
-
- /* Generate a hash across the pool, 16 words (512 bits) at a time */
- spin_lock_irqsave(&r->lock, flags);
- for (i = 0; i < r->poolinfo->poolwords; i += 16)
- sha_transform(hash.w, (__u8 *)(r->pool + i), workspace);
-
- /*
- * We mix the hash back into the pool to prevent backtracking
- * attacks (where the attacker knows the state of the pool
- * plus the current outputs, and attempts to find previous
- * ouputs), unless the hash function can be inverted. By
- * mixing at least a SHA1 worth of hash data back, we make
- * brute-forcing the feedback as hard as brute-forcing the
- * hash.
- */
- __mix_pool_bytes(r, hash.w, sizeof(hash.w));
- spin_unlock_irqrestore(&r->lock, flags);
-
- memzero_explicit(workspace, sizeof(workspace));
-
- /*
- * In case the hash function has some recognizable output
- * pattern, we fold it in half. Thus, we always feed back
- * twice as much data as we output.
- */
- hash.w[0] ^= hash.w[3];
- hash.w[1] ^= hash.w[4];
- hash.w[2] ^= rol32(hash.w[2], 16);
-
- memcpy(out, &hash, EXTRACT_SIZE);
- memzero_explicit(&hash, sizeof(hash));
}
-
-static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int fips)
-{
- ssize_t ret = 0, i;
- __u8 tmp[EXTRACT_SIZE];
- unsigned long flags;
-
- while (nbytes) {
- extract_buf(r, tmp);
-
- if (fips) {
- spin_lock_irqsave(&r->lock, flags);
- if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
- panic("Hardware RNG duplicated output!\n");
- memcpy(r->last_data, tmp, EXTRACT_SIZE);
- spin_unlock_irqrestore(&r->lock, flags);
- }
- i = min_t(int, nbytes, EXTRACT_SIZE);
- memcpy(buf, tmp, i);
- nbytes -= i;
- buf += i;
- ret += i;
- }
-
- /* Wipe data just returned from memory */
- memzero_explicit(tmp, sizeof(tmp));
-
- return ret;
-}
-
-/*
- * This function extracts randomness from the "entropy pool", and
- * returns it in a buffer.
- *
- * The min parameter specifies the minimum amount we can pull before
- * failing to avoid races that defeat catastrophic reseeding while the
- * reserved parameter indicates how much entropy we must leave in the
- * pool after each pull to avoid starving other readers.
- */
-static ssize_t extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int min, int reserved)
-{
- __u8 tmp[EXTRACT_SIZE];
- unsigned long flags;
-
- /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
- if (fips_enabled) {
- spin_lock_irqsave(&r->lock, flags);
- if (!r->last_data_init) {
- r->last_data_init = 1;
- spin_unlock_irqrestore(&r->lock, flags);
- trace_extract_entropy(r->name, EXTRACT_SIZE,
- ENTROPY_BITS(r), _RET_IP_);
- extract_buf(r, tmp);
- spin_lock_irqsave(&r->lock, flags);
- memcpy(r->last_data, tmp, EXTRACT_SIZE);
- }
- spin_unlock_irqrestore(&r->lock, flags);
- }
-
- trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
- nbytes = account(r, nbytes, min, reserved);
-
- return _extract_entropy(r, buf, nbytes, fips_enabled);
-}
-
-#define warn_unseeded_randomness(previous) \
- _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous))
-
-static void _warn_unseeded_randomness(const char *func_name, void *caller,
- void **previous)
-{
-#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
- const bool print_once = false;
-#else
- static bool print_once __read_mostly;
#endif
-
- if (print_once ||
- crng_ready() ||
- (previous && (caller == READ_ONCE(*previous))))
- return;
- WRITE_ONCE(*previous, caller);
-#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
- print_once = true;
-#endif
- if (__ratelimit(&unseeded_warning))
- pr_notice("random: %s called from %pS with crng_init=%d\n",
- func_name, caller, crng_init);
-}
-
-/*
- * This function is the exported kernel interface. It returns some
- * number of good random numbers, suitable for key generation, seeding
- * TCP sequence numbers, etc. It does not rely on the hardware random
- * number generator. For random bytes direct from the hardware RNG
- * (when available), use get_random_bytes_arch(). In order to ensure
- * that the randomness provided by this function is okay, the function
- * wait_for_random_bytes() should be called and return 0 at least once
- * at any point prior.
- */
-static void _get_random_bytes(void *buf, int nbytes)
-{
- __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
-
- trace_get_random_bytes(nbytes, _RET_IP_);
-
- while (nbytes >= CHACHA_BLOCK_SIZE) {
- extract_crng(buf);
- buf += CHACHA_BLOCK_SIZE;
- nbytes -= CHACHA_BLOCK_SIZE;
- }
-
- if (nbytes > 0) {
- extract_crng(tmp);
- memcpy(buf, tmp, nbytes);
- crng_backtrack_protect(tmp, nbytes);
- } else
- crng_backtrack_protect(tmp, CHACHA_BLOCK_SIZE);
- memzero_explicit(tmp, sizeof(tmp));
-}
-
-void get_random_bytes(void *buf, int nbytes)
-{
- static void *previous;
-
- warn_unseeded_randomness(&previous);
- _get_random_bytes(buf, nbytes);
-}
-EXPORT_SYMBOL(get_random_bytes);
-
/*
* Each time the timer fires, we expect that we got an unpredictable
@@ -1566,99 +1155,401 @@
*
* So the re-arming always happens in the entropy loop itself.
*/
-static void entropy_timer(struct timer_list *t)
+static void __cold entropy_timer(struct timer_list *t)
{
- credit_entropy_bits(&input_pool, 1);
+ credit_init_bits(1);
}
/*
* If we have an actual cycle counter, see if we can
* generate enough entropy with timing noise
*/
-static void try_to_generate_entropy(void)
+static void __cold try_to_generate_entropy(void)
{
struct {
- unsigned long now;
+ unsigned long entropy;
struct timer_list timer;
} stack;
- stack.now = random_get_entropy();
+ stack.entropy = random_get_entropy();
-#ifndef CONFIG_ARCH_ROCKCHIP
/* Slow counter - or none. Don't even bother */
- if (stack.now == random_get_entropy())
+ if (stack.entropy == random_get_entropy())
return;
-#endif
timer_setup_on_stack(&stack.timer, entropy_timer, 0);
- while (!crng_ready()) {
+ while (!crng_ready() && !signal_pending(current)) {
if (!timer_pending(&stack.timer))
- mod_timer(&stack.timer, jiffies+1);
- mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now));
+ mod_timer(&stack.timer, jiffies + 1);
+ mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
schedule();
- stack.now = random_get_entropy();
+ stack.entropy = random_get_entropy();
}
del_timer_sync(&stack.timer);
destroy_timer_on_stack(&stack.timer);
- mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now));
+ mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
}
-/*
- * Wait for the urandom pool to be seeded and thus guaranteed to supply
- * cryptographically secure random numbers. This applies to: the /dev/urandom
- * device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
- * family of functions. Using any of these functions without first calling
- * this function forfeits the guarantee of security.
+
+/**********************************************************************
*
- * Returns: 0 if the urandom pool has been seeded.
- * -ERESTARTSYS if the function was interrupted by a signal.
- */
-int wait_for_random_bytes(void)
+ * Userspace reader/writer interfaces.
+ *
+ * getrandom(2) is the primary modern interface into the RNG and should
+ * be used in preference to anything else.
+ *
+ * Reading from /dev/random has the same functionality as calling
+ * getrandom(2) with flags=0. In earlier versions, however, it had
+ * vastly different semantics and should therefore be avoided, to
+ * prevent backwards compatibility issues.
+ *
+ * Reading from /dev/urandom has the same functionality as calling
+ * getrandom(2) with flags=GRND_INSECURE. Because it does not block
+ * waiting for the RNG to be ready, it should not be used.
+ *
+ * Writing to either /dev/random or /dev/urandom adds entropy to
+ * the input pool but does not credit it.
+ *
+ * Polling on /dev/random indicates when the RNG is initialized, on
+ * the read side, and when it wants new entropy, on the write side.
+ *
+ * Both /dev/random and /dev/urandom have the same set of ioctls for
+ * adding entropy, getting the entropy count, zeroing the count, and
+ * reseeding the crng.
+ *
+ **********************************************************************/
+
+SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags)
{
- if (likely(crng_ready()))
+ struct iov_iter iter;
+ struct iovec iov;
+ int ret;
+
+ if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))
+ return -EINVAL;
+
+ /*
+ * Requesting insecure and blocking randomness at the same time makes
+ * no sense.
+ */
+ if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM))
+ return -EINVAL;
+
+ if (!crng_ready() && !(flags & GRND_INSECURE)) {
+ if (flags & GRND_NONBLOCK)
+ return -EAGAIN;
+ ret = wait_for_random_bytes();
+ if (unlikely(ret))
+ return ret;
+ }
+
+ ret = import_single_range(READ, ubuf, len, &iov, &iter);
+ if (unlikely(ret))
+ return ret;
+ return get_random_bytes_user(&iter);
+}
+
+static __poll_t random_poll(struct file *file, poll_table *wait)
+{
+ poll_wait(file, &crng_init_wait, wait);
+ return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM;
+}
+
+static ssize_t write_pool_user(struct iov_iter *iter)
+{
+ u8 block[BLAKE2S_BLOCK_SIZE];
+ ssize_t ret = 0;
+ size_t copied;
+
+ if (unlikely(!iov_iter_count(iter)))
return 0;
-#ifdef CONFIG_ARCH_ROCKCHIP
- try_to_generate_entropy();
-#endif
+ for (;;) {
+ copied = copy_from_iter(block, sizeof(block), iter);
+ ret += copied;
+ mix_pool_bytes(block, copied);
+ if (!iov_iter_count(iter) || copied != sizeof(block))
+ break;
- do {
- int ret;
- ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
- if (ret)
- return ret > 0 ? 0 : ret;
+ BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0);
+ if (ret % PAGE_SIZE == 0) {
+ if (signal_pending(current))
+ break;
+ cond_resched();
+ }
+ }
- try_to_generate_entropy();
- } while (!crng_ready());
-
- return 0;
+ memzero_explicit(block, sizeof(block));
+ return ret ? ret : -EFAULT;
}
-EXPORT_SYMBOL(wait_for_random_bytes);
-/*
- * Returns whether or not the urandom pool has been seeded and thus guaranteed
- * to supply cryptographically secure random numbers. This applies to: the
- * /dev/urandom device, the get_random_bytes function, and the get_random_{u32,
- * ,u64,int,long} family of functions.
- *
- * Returns: true if the urandom pool has been seeded.
- * false if the urandom pool has not been seeded.
- */
-bool rng_is_initialized(void)
+static ssize_t random_write_iter(struct kiocb *kiocb, struct iov_iter *iter)
{
- return crng_ready();
+ return write_pool_user(iter);
}
-EXPORT_SYMBOL(rng_is_initialized);
+
+static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
+{
+ static int maxwarn = 10;
+
+ if (!crng_ready()) {
+ if (!ratelimit_disable && maxwarn <= 0)
+ ++urandom_warning.missed;
+ else if (ratelimit_disable || __ratelimit(&urandom_warning)) {
+ --maxwarn;
+ pr_notice("%s: uninitialized urandom read (%zu bytes read)\n",
+ current->comm, iov_iter_count(iter));
+ }
+ }
+
+ return get_random_bytes_user(iter);
+}
+
+static ssize_t random_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
+{
+ int ret;
+
+ if (!crng_ready() &&
+ ((kiocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) ||
+ (kiocb->ki_filp->f_flags & O_NONBLOCK)))
+ return -EAGAIN;
+
+ ret = wait_for_random_bytes();
+ if (ret != 0)
+ return ret;
+ return get_random_bytes_user(iter);
+}
+
+static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
+{
+ int __user *p = (int __user *)arg;
+ int ent_count;
+
+ switch (cmd) {
+ case RNDGETENTCNT:
+ /* Inherently racy, no point locking. */
+ if (put_user(input_pool.init_bits, p))
+ return -EFAULT;
+ return 0;
+ case RNDADDTOENTCNT:
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (get_user(ent_count, p))
+ return -EFAULT;
+ if (ent_count < 0)
+ return -EINVAL;
+ credit_init_bits(ent_count);
+ return 0;
+ case RNDADDENTROPY: {
+ struct iov_iter iter;
+ struct iovec iov;
+ ssize_t ret;
+ int len;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (get_user(ent_count, p++))
+ return -EFAULT;
+ if (ent_count < 0)
+ return -EINVAL;
+ if (get_user(len, p++))
+ return -EFAULT;
+ ret = import_single_range(WRITE, p, len, &iov, &iter);
+ if (unlikely(ret))
+ return ret;
+ ret = write_pool_user(&iter);
+ if (unlikely(ret < 0))
+ return ret;
+ /* Since we're crediting, enforce that it was all written into the pool. */
+ if (unlikely(ret != len))
+ return -EFAULT;
+ credit_init_bits(ent_count);
+ return 0;
+ }
+ case RNDZAPENTCNT:
+ case RNDCLEARPOOL:
+ /* No longer has any effect. */
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ return 0;
+ case RNDRESEEDCRNG:
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (!crng_ready())
+ return -ENODATA;
+ crng_reseed();
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int random_fasync(int fd, struct file *filp, int on)
+{
+ return fasync_helper(fd, filp, on, &fasync);
+}
+
+const struct file_operations random_fops = {
+ .read_iter = random_read_iter,
+ .write_iter = random_write_iter,
+ .poll = random_poll,
+ .unlocked_ioctl = random_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
+ .fasync = random_fasync,
+ .llseek = noop_llseek,
+ .splice_read = generic_file_splice_read,
+ .splice_write = iter_file_splice_write,
+};
+
+const struct file_operations urandom_fops = {
+ .read_iter = urandom_read_iter,
+ .write_iter = random_write_iter,
+ .unlocked_ioctl = random_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
+ .fasync = random_fasync,
+ .llseek = noop_llseek,
+ .splice_read = generic_file_splice_read,
+ .splice_write = iter_file_splice_write,
+};
+
+
+/********************************************************************
+ *
+ * Sysctl interface.
+ *
+ * These are partly unused legacy knobs with dummy values to not break
+ * userspace and partly still useful things. They are usually accessible
+ * in /proc/sys/kernel/random/ and are as follows:
+ *
+ * - boot_id - a UUID representing the current boot.
+ *
+ * - uuid - a random UUID, different each time the file is read.
+ *
+ * - poolsize - the number of bits of entropy that the input pool can
+ * hold, tied to the POOL_BITS constant.
+ *
+ * - entropy_avail - the number of bits of entropy currently in the
+ * input pool. Always <= poolsize.
+ *
+ * - write_wakeup_threshold - the amount of entropy in the input pool
+ * below which write polls to /dev/random will unblock, requesting
+ * more entropy, tied to the POOL_READY_BITS constant. It is writable
+ * to avoid breaking old userspaces, but writing to it does not
+ * change any behavior of the RNG.
+ *
+ * - urandom_min_reseed_secs - fixed to the value CRNG_RESEED_INTERVAL.
+ * It is writable to avoid breaking old userspaces, but writing
+ * to it does not change any behavior of the RNG.
+ *
+ ********************************************************************/
+
+#ifdef CONFIG_SYSCTL
+
+#include <linux/sysctl.h>
+
+static int sysctl_random_min_urandom_seed = CRNG_RESEED_INTERVAL / HZ;
+static int sysctl_random_write_wakeup_bits = POOL_READY_BITS;
+static int sysctl_poolsize = POOL_BITS;
+static u8 sysctl_bootid[UUID_SIZE];
/*
- * Add a callback function that will be invoked when the nonblocking
- * pool is initialised.
- *
- * returns: 0 if callback is successfully added
- * -EALREADY if pool is already initialised (callback not called)
- * -ENOENT if module for callback is not alive
+ * This function is used to return both the bootid UUID, and random
+ * UUID. The difference is in whether table->data is NULL; if it is,
+ * then a new UUID is generated and returned to the user.
*/
+static int proc_do_uuid(struct ctl_table *table, int write, void *buf,
+ size_t *lenp, loff_t *ppos)
+{
+ u8 tmp_uuid[UUID_SIZE], *uuid;
+ char uuid_string[UUID_STRING_LEN + 1];
+ struct ctl_table fake_table = {
+ .data = uuid_string,
+ .maxlen = UUID_STRING_LEN
+ };
+
+ if (write)
+ return -EPERM;
+
+ uuid = table->data;
+ if (!uuid) {
+ uuid = tmp_uuid;
+ generate_random_uuid(uuid);
+ } else {
+ static DEFINE_SPINLOCK(bootid_spinlock);
+
+ spin_lock(&bootid_spinlock);
+ if (!uuid[8])
+ generate_random_uuid(uuid);
+ spin_unlock(&bootid_spinlock);
+ }
+
+ snprintf(uuid_string, sizeof(uuid_string), "%pU", uuid);
+ return proc_dostring(&fake_table, 0, buf, lenp, ppos);
+}
+
+/* The same as proc_dointvec, but writes don't change anything. */
+static int proc_do_rointvec(struct ctl_table *table, int write, void *buf,
+ size_t *lenp, loff_t *ppos)
+{
+ return write ? 0 : proc_dointvec(table, 0, buf, lenp, ppos);
+}
+
+extern struct ctl_table random_table[];
+struct ctl_table random_table[] = {
+ {
+ .procname = "poolsize",
+ .data = &sysctl_poolsize,
+ .maxlen = sizeof(int),
+ .mode = 0444,
+ .proc_handler = proc_dointvec,
+ },
+ {
+ .procname = "entropy_avail",
+ .data = &input_pool.init_bits,
+ .maxlen = sizeof(int),
+ .mode = 0444,
+ .proc_handler = proc_dointvec,
+ },
+ {
+ .procname = "write_wakeup_threshold",
+ .data = &sysctl_random_write_wakeup_bits,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_do_rointvec,
+ },
+ {
+ .procname = "urandom_min_reseed_secs",
+ .data = &sysctl_random_min_urandom_seed,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_do_rointvec,
+ },
+ {
+ .procname = "boot_id",
+ .data = &sysctl_bootid,
+ .mode = 0444,
+ .proc_handler = proc_do_uuid,
+ },
+ {
+ .procname = "uuid",
+ .mode = 0444,
+ .proc_handler = proc_do_uuid,
+ },
+ { }
+};
+#endif /* CONFIG_SYSCTL */
+
+/*
+ * Android KABI fixups
+ *
+ * Add back two functions that were being used by out-of-tree drivers.
+ *
+ * Yes, horrible hack, the things we do for FIPS "compliance"...
+ */
+static DEFINE_SPINLOCK(random_ready_list_lock);
+static LIST_HEAD(random_ready_list);
+
int add_random_ready_callback(struct random_ready_callback *rdy)
{
struct module *owner;
@@ -1690,9 +1581,6 @@
}
EXPORT_SYMBOL(add_random_ready_callback);
-/*
- * Delete a previously registered readiness callback function.
- */
void del_random_ready_callback(struct random_ready_callback *rdy)
{
unsigned long flags;
@@ -1709,601 +1597,18 @@
}
EXPORT_SYMBOL(del_random_ready_callback);
-/*
- * This function will use the architecture-specific hardware random
- * number generator if it is available. The arch-specific hw RNG will
- * almost certainly be faster than what we can do in software, but it
- * is impossible to verify that it is implemented securely (as
- * opposed, to, say, the AES encryption of a sequence number using a
- * key known by the NSA). So it's useful if we need the speed, but
- * only if we're willing to trust the hardware manufacturer not to
- * have put in a back door.
- *
- * Return number of bytes filled in.
- */
-int __must_check get_random_bytes_arch(void *buf, int nbytes)
-{
- int left = nbytes;
- char *p = buf;
-
- trace_get_random_bytes_arch(left, _RET_IP_);
- while (left) {
- unsigned long v;
- int chunk = min_t(int, left, sizeof(unsigned long));
-
- if (!arch_get_random_long(&v))
- break;
-
- memcpy(p, &v, chunk);
- p += chunk;
- left -= chunk;
- }
-
- return nbytes - left;
-}
-EXPORT_SYMBOL(get_random_bytes_arch);
-
-/*
- * init_std_data - initialize pool with system data
- *
- * @r: pool to initialize
- *
- * This function clears the pool's entropy count and mixes some system
- * data into the pool to prepare it for use. The pool is not cleared
- * as that can only decrease the entropy in the pool.
- */
-static void __init init_std_data(struct entropy_store *r)
-{
- int i;
- ktime_t now = ktime_get_real();
- unsigned long rv;
-
- mix_pool_bytes(r, &now, sizeof(now));
- for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv))
- rv = random_get_entropy();
- mix_pool_bytes(r, &rv, sizeof(rv));
- }
- mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
-}
-
-/*
- * Note that setup_arch() may call add_device_randomness()
- * long before we get here. This allows seeding of the pools
- * with some platform dependent data very early in the boot
- * process. But it limits our options here. We must use
- * statically allocated structures that already have all
- * initializations complete at compile time. We should also
- * take care not to overwrite the precious per platform data
- * we were given.
- */
-int __init rand_initialize(void)
-{
- init_std_data(&input_pool);
- crng_initialize(&primary_crng);
- crng_global_init_time = jiffies;
- if (ratelimit_disable) {
- urandom_warning.interval = 0;
- unseeded_warning.interval = 0;
- }
- return 0;
-}
-
-#ifdef CONFIG_BLOCK
-void rand_initialize_disk(struct gendisk *disk)
-{
- struct timer_rand_state *state;
-
- /*
- * If kzalloc returns null, we just won't use that entropy
- * source.
- */
- state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
- if (state) {
- state->last_time = INITIAL_JIFFIES;
- disk->random = state;
- }
-}
-#endif
-
-static ssize_t
-urandom_read_nowarn(struct file *file, char __user *buf, size_t nbytes,
- loff_t *ppos)
-{
- int ret;
-
- nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
- ret = extract_crng_user(buf, nbytes);
- trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool));
- return ret;
-}
-
-static ssize_t
-urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
+static void process_oldschool_random_ready_list(void)
{
unsigned long flags;
- static int maxwarn = 10;
+ struct random_ready_callback *rdy, *tmp;
- if (!crng_ready() && maxwarn > 0) {
- maxwarn--;
- if (__ratelimit(&urandom_warning))
- pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
- current->comm, nbytes);
- spin_lock_irqsave(&primary_crng.lock, flags);
- crng_init_cnt = 0;
- spin_unlock_irqrestore(&primary_crng.lock, flags);
+ spin_lock_irqsave(&random_ready_list_lock, flags);
+ list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
+ struct module *owner = rdy->owner;
+
+ list_del_init(&rdy->list);
+ rdy->func(rdy);
+ module_put(owner);
}
-
- return urandom_read_nowarn(file, buf, nbytes, ppos);
+ spin_unlock_irqrestore(&random_ready_list_lock, flags);
}
-
-static ssize_t
-random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
-{
- int ret;
-
- ret = wait_for_random_bytes();
- if (ret != 0)
- return ret;
- return urandom_read_nowarn(file, buf, nbytes, ppos);
-}
-
-static __poll_t
-random_poll(struct file *file, poll_table * wait)
-{
- __poll_t mask;
-
- poll_wait(file, &crng_init_wait, wait);
- poll_wait(file, &random_write_wait, wait);
- mask = 0;
- if (crng_ready())
- mask |= EPOLLIN | EPOLLRDNORM;
- if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
- mask |= EPOLLOUT | EPOLLWRNORM;
- return mask;
-}
-
-static int
-write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
-{
- size_t bytes;
- __u32 t, buf[16];
- const char __user *p = buffer;
-
- while (count > 0) {
- int b, i = 0;
-
- bytes = min(count, sizeof(buf));
- if (copy_from_user(&buf, p, bytes))
- return -EFAULT;
-
- for (b = bytes ; b > 0 ; b -= sizeof(__u32), i++) {
- if (!arch_get_random_int(&t))
- break;
- buf[i] ^= t;
- }
-
- count -= bytes;
- p += bytes;
-
- mix_pool_bytes(r, buf, bytes);
- cond_resched();
- }
-
- return 0;
-}
-
-static ssize_t random_write(struct file *file, const char __user *buffer,
- size_t count, loff_t *ppos)
-{
- size_t ret;
-
- ret = write_pool(&input_pool, buffer, count);
- if (ret)
- return ret;
-
- return (ssize_t)count;
-}
-
-static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
-{
- int size, ent_count;
- int __user *p = (int __user *)arg;
- int retval;
-
- switch (cmd) {
- case RNDGETENTCNT:
- /* inherently racy, no point locking */
- ent_count = ENTROPY_BITS(&input_pool);
- if (put_user(ent_count, p))
- return -EFAULT;
- return 0;
- case RNDADDTOENTCNT:
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- if (get_user(ent_count, p))
- return -EFAULT;
- return credit_entropy_bits_safe(&input_pool, ent_count);
- case RNDADDENTROPY:
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- if (get_user(ent_count, p++))
- return -EFAULT;
- if (ent_count < 0)
- return -EINVAL;
- if (get_user(size, p++))
- return -EFAULT;
- retval = write_pool(&input_pool, (const char __user *)p,
- size);
- if (retval < 0)
- return retval;
- return credit_entropy_bits_safe(&input_pool, ent_count);
- case RNDZAPENTCNT:
- case RNDCLEARPOOL:
- /*
- * Clear the entropy pool counters. We no longer clear
- * the entropy pool, as that's silly.
- */
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- input_pool.entropy_count = 0;
- return 0;
- case RNDRESEEDCRNG:
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- if (crng_init < 2)
- return -ENODATA;
- crng_reseed(&primary_crng, &input_pool);
- WRITE_ONCE(crng_global_init_time, jiffies - 1);
- return 0;
- default:
- return -EINVAL;
- }
-}
-
-static int random_fasync(int fd, struct file *filp, int on)
-{
- return fasync_helper(fd, filp, on, &fasync);
-}
-
-const struct file_operations random_fops = {
- .read = random_read,
- .write = random_write,
- .poll = random_poll,
- .unlocked_ioctl = random_ioctl,
- .fasync = random_fasync,
- .llseek = noop_llseek,
-};
-
-const struct file_operations urandom_fops = {
- .read = urandom_read,
- .write = random_write,
- .unlocked_ioctl = random_ioctl,
- .fasync = random_fasync,
- .llseek = noop_llseek,
-};
-
-SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
- unsigned int, flags)
-{
- int ret;
-
- if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE))
- return -EINVAL;
-
- /*
- * Requesting insecure and blocking randomness at the same time makes
- * no sense.
- */
- if ((flags & (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|GRND_RANDOM))
- return -EINVAL;
-
- if (count > INT_MAX)
- count = INT_MAX;
-
- if (!(flags & GRND_INSECURE) && !crng_ready()) {
- if (flags & GRND_NONBLOCK)
- return -EAGAIN;
- ret = wait_for_random_bytes();
- if (unlikely(ret))
- return ret;
- }
- return urandom_read_nowarn(NULL, buf, count, NULL);
-}
-
-/********************************************************************
- *
- * Sysctl interface
- *
- ********************************************************************/
-
-#ifdef CONFIG_SYSCTL
-
-#include <linux/sysctl.h>
-
-static int min_write_thresh;
-static int max_write_thresh = INPUT_POOL_WORDS * 32;
-static int random_min_urandom_seed = 60;
-static char sysctl_bootid[16];
-
-/*
- * This function is used to return both the bootid UUID, and random
- * UUID. The difference is in whether table->data is NULL; if it is,
- * then a new UUID is generated and returned to the user.
- *
- * If the user accesses this via the proc interface, the UUID will be
- * returned as an ASCII string in the standard UUID format; if via the
- * sysctl system call, as 16 bytes of binary data.
- */
-static int proc_do_uuid(struct ctl_table *table, int write,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- struct ctl_table fake_table;
- unsigned char buf[64], tmp_uuid[16], *uuid;
-
- uuid = table->data;
- if (!uuid) {
- uuid = tmp_uuid;
- generate_random_uuid(uuid);
- } else {
- static DEFINE_SPINLOCK(bootid_spinlock);
-
- spin_lock(&bootid_spinlock);
- if (!uuid[8])
- generate_random_uuid(uuid);
- spin_unlock(&bootid_spinlock);
- }
-
- sprintf(buf, "%pU", uuid);
-
- fake_table.data = buf;
- fake_table.maxlen = sizeof(buf);
-
- return proc_dostring(&fake_table, write, buffer, lenp, ppos);
-}
-
-/*
- * Return entropy available scaled to integral bits
- */
-static int proc_do_entropy(struct ctl_table *table, int write,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- struct ctl_table fake_table;
- int entropy_count;
-
- entropy_count = *(int *)table->data >> ENTROPY_SHIFT;
-
- fake_table.data = &entropy_count;
- fake_table.maxlen = sizeof(entropy_count);
-
- return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
-}
-
-static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
-extern struct ctl_table random_table[];
-struct ctl_table random_table[] = {
- {
- .procname = "poolsize",
- .data = &sysctl_poolsize,
- .maxlen = sizeof(int),
- .mode = 0444,
- .proc_handler = proc_dointvec,
- },
- {
- .procname = "entropy_avail",
- .maxlen = sizeof(int),
- .mode = 0444,
- .proc_handler = proc_do_entropy,
- .data = &input_pool.entropy_count,
- },
- {
- .procname = "write_wakeup_threshold",
- .data = &random_write_wakeup_bits,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = &min_write_thresh,
- .extra2 = &max_write_thresh,
- },
- {
- .procname = "urandom_min_reseed_secs",
- .data = &random_min_urandom_seed,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec,
- },
- {
- .procname = "boot_id",
- .data = &sysctl_bootid,
- .maxlen = 16,
- .mode = 0444,
- .proc_handler = proc_do_uuid,
- },
- {
- .procname = "uuid",
- .maxlen = 16,
- .mode = 0444,
- .proc_handler = proc_do_uuid,
- },
-#ifdef ADD_INTERRUPT_BENCH
- {
- .procname = "add_interrupt_avg_cycles",
- .data = &avg_cycles,
- .maxlen = sizeof(avg_cycles),
- .mode = 0444,
- .proc_handler = proc_doulongvec_minmax,
- },
- {
- .procname = "add_interrupt_avg_deviation",
- .data = &avg_deviation,
- .maxlen = sizeof(avg_deviation),
- .mode = 0444,
- .proc_handler = proc_doulongvec_minmax,
- },
-#endif
- { }
-};
-#endif /* CONFIG_SYSCTL */
-
-struct batched_entropy {
- union {
- u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)];
- u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)];
- };
- unsigned int position;
- spinlock_t batch_lock;
-};
-
-/*
- * Get a random word for internal kernel use only. The quality of the random
- * number is good as /dev/urandom, but there is no backtrack protection, with
- * the goal of being quite fast and not depleting entropy. In order to ensure
- * that the randomness provided by this function is okay, the function
- * wait_for_random_bytes() should be called and return 0 at least once at any
- * point prior.
- */
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
- .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock),
-};
-
-u64 get_random_u64(void)
-{
- u64 ret;
- unsigned long flags;
- struct batched_entropy *batch;
- static void *previous;
-
- warn_unseeded_randomness(&previous);
-
- batch = raw_cpu_ptr(&batched_entropy_u64);
- spin_lock_irqsave(&batch->batch_lock, flags);
- if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
- extract_crng((u8 *)batch->entropy_u64);
- batch->position = 0;
- }
- ret = batch->entropy_u64[batch->position++];
- spin_unlock_irqrestore(&batch->batch_lock, flags);
- return ret;
-}
-EXPORT_SYMBOL(get_random_u64);
-
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
- .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock),
-};
-u32 get_random_u32(void)
-{
- u32 ret;
- unsigned long flags;
- struct batched_entropy *batch;
- static void *previous;
-
- warn_unseeded_randomness(&previous);
-
- batch = raw_cpu_ptr(&batched_entropy_u32);
- spin_lock_irqsave(&batch->batch_lock, flags);
- if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
- extract_crng((u8 *)batch->entropy_u32);
- batch->position = 0;
- }
- ret = batch->entropy_u32[batch->position++];
- spin_unlock_irqrestore(&batch->batch_lock, flags);
- return ret;
-}
-EXPORT_SYMBOL(get_random_u32);
-
-/* It's important to invalidate all potential batched entropy that might
- * be stored before the crng is initialized, which we can do lazily by
- * simply resetting the counter to zero so that it's re-extracted on the
- * next usage. */
-static void invalidate_batched_entropy(void)
-{
- int cpu;
- unsigned long flags;
-
- for_each_possible_cpu (cpu) {
- struct batched_entropy *batched_entropy;
-
- batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu);
- spin_lock_irqsave(&batched_entropy->batch_lock, flags);
- batched_entropy->position = 0;
- spin_unlock(&batched_entropy->batch_lock);
-
- batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu);
- spin_lock(&batched_entropy->batch_lock);
- batched_entropy->position = 0;
- spin_unlock_irqrestore(&batched_entropy->batch_lock, flags);
- }
-}
-
-/**
- * randomize_page - Generate a random, page aligned address
- * @start: The smallest acceptable address the caller will take.
- * @range: The size of the area, starting at @start, within which the
- * random address must fall.
- *
- * If @start + @range would overflow, @range is capped.
- *
- * NOTE: Historical use of randomize_range, which this replaces, presumed that
- * @start was already page aligned. We now align it regardless.
- *
- * Return: A page aligned address within [start, start + range). On error,
- * @start is returned.
- */
-unsigned long
-randomize_page(unsigned long start, unsigned long range)
-{
- if (!PAGE_ALIGNED(start)) {
- range -= PAGE_ALIGN(start) - start;
- start = PAGE_ALIGN(start);
- }
-
- if (start > ULONG_MAX - range)
- range = ULONG_MAX - start;
-
- range >>= PAGE_SHIFT;
-
- if (range == 0)
- return start;
-
- return start + (get_random_long() % range << PAGE_SHIFT);
-}
-
-/* Interface for in-kernel drivers of true hardware RNGs.
- * Those devices may produce endless random bits and will be throttled
- * when our pool is full.
- */
-void add_hwgenerator_randomness(const char *buffer, size_t count,
- size_t entropy)
-{
- struct entropy_store *poolp = &input_pool;
-
- if (unlikely(crng_init == 0)) {
- crng_fast_load(buffer, count);
- return;
- }
-
- /* Suspend writing if we're above the trickle threshold.
- * We'll be woken up again once below random_write_wakeup_thresh,
- * or when the calling thread is about to terminate.
- */
- wait_event_interruptible(random_write_wait, kthread_should_stop() ||
- ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
- mix_pool_bytes(poolp, buffer, count);
- credit_entropy_bits(poolp, entropy);
-}
-EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
-
-/* Handle random seed passed by bootloader.
- * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise
- * it would be regarded as device data.
- * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
- */
-void add_bootloader_randomness(const void *buf, unsigned int size)
-{
- if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
- add_hwgenerator_randomness(buf, size, size * 8);
- else
- add_device_randomness(buf, size);
-}
-EXPORT_SYMBOL_GPL(add_bootloader_randomness);
\ No newline at end of file
--
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