From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/mm/maccess.c | 279 ++++++++++++++++++++++++++++++++++---------------------
1 files changed, 173 insertions(+), 106 deletions(-)
diff --git a/kernel/mm/maccess.c b/kernel/mm/maccess.c
index 6e41ba4..f6ea117 100644
--- a/kernel/mm/maccess.c
+++ b/kernel/mm/maccess.c
@@ -1,94 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
- * Access kernel memory without faulting.
+ * Access kernel or user memory without faulting.
*/
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
-static __always_inline long
-probe_read_common(void *dst, const void __user *src, size_t size)
+bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,
+ size_t size)
{
- long ret;
-
- pagefault_disable();
- ret = __copy_from_user_inatomic(dst, src, size);
- pagefault_enable();
-
- return ret ? -EFAULT : 0;
+ return true;
}
-static __always_inline long
-probe_write_common(void __user *dst, const void *src, size_t size)
+#ifdef HAVE_GET_KERNEL_NOFAULT
+
+#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label) \
+ while (len >= sizeof(type)) { \
+ __get_kernel_nofault(dst, src, type, err_label); \
+ dst += sizeof(type); \
+ src += sizeof(type); \
+ len -= sizeof(type); \
+ }
+
+long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
{
- long ret;
+ if (!copy_from_kernel_nofault_allowed(src, size))
+ return -ERANGE;
pagefault_disable();
- ret = __copy_to_user_inatomic(dst, src, size);
+ copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
+ copy_from_kernel_nofault_loop(dst, src, size, u32, Efault);
+ copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);
+ copy_from_kernel_nofault_loop(dst, src, size, u8, Efault);
pagefault_enable();
+ return 0;
+Efault:
+ pagefault_enable();
+ return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
- return ret ? -EFAULT : 0;
+#define copy_to_kernel_nofault_loop(dst, src, len, type, err_label) \
+ while (len >= sizeof(type)) { \
+ __put_kernel_nofault(dst, src, type, err_label); \
+ dst += sizeof(type); \
+ src += sizeof(type); \
+ len -= sizeof(type); \
+ }
+
+long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
+{
+ pagefault_disable();
+ copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
+ copy_to_kernel_nofault_loop(dst, src, size, u32, Efault);
+ copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);
+ copy_to_kernel_nofault_loop(dst, src, size, u8, Efault);
+ pagefault_enable();
+ return 0;
+Efault:
+ pagefault_enable();
+ return -EFAULT;
}
+long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
+{
+ const void *src = unsafe_addr;
+
+ if (unlikely(count <= 0))
+ return 0;
+ if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))
+ return -ERANGE;
+
+ pagefault_disable();
+ do {
+ __get_kernel_nofault(dst, src, u8, Efault);
+ dst++;
+ src++;
+ } while (dst[-1] && src - unsafe_addr < count);
+ pagefault_enable();
+
+ dst[-1] = '\0';
+ return src - unsafe_addr;
+Efault:
+ pagefault_enable();
+ dst[0] = '\0';
+ return -EFAULT;
+}
+#else /* HAVE_GET_KERNEL_NOFAULT */
/**
- * probe_kernel_read(): safely attempt to read from a kernel-space location
+ * copy_from_kernel_nofault(): safely attempt to read from kernel-space
* @dst: pointer to the buffer that shall take the data
* @src: address to read from
* @size: size of the data chunk
*
- * Safely read from address @src to the buffer at @dst. If a kernel fault
- * happens, handle that and return -EFAULT.
+ * Safely read from kernel address @src to the buffer at @dst. If a kernel
+ * fault happens, handle that and return -EFAULT. If @src is not a valid kernel
+ * address, return -ERANGE.
*
* We ensure that the copy_from_user is executed in atomic context so that
- * do_page_fault() doesn't attempt to take mmap_sem. This makes
- * probe_kernel_read() suitable for use within regions where the caller
- * already holds mmap_sem, or other locks which nest inside mmap_sem.
+ * do_page_fault() doesn't attempt to take mmap_lock. This makes
+ * copy_from_kernel_nofault() suitable for use within regions where the caller
+ * already holds mmap_lock, or other locks which nest inside mmap_lock.
*/
-
-long __weak probe_kernel_read(void *dst, const void *src, size_t size)
- __attribute__((alias("__probe_kernel_read")));
-
-long __probe_kernel_read(void *dst, const void *src, size_t size)
+long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
{
long ret;
mm_segment_t old_fs = get_fs();
+ if (!copy_from_kernel_nofault_allowed(src, size))
+ return -ERANGE;
+
set_fs(KERNEL_DS);
- ret = probe_read_common(dst, (__force const void __user *)src, size);
+ pagefault_disable();
+ ret = __copy_from_user_inatomic(dst, (__force const void __user *)src,
+ size);
+ pagefault_enable();
set_fs(old_fs);
- return ret;
+ if (ret)
+ return -EFAULT;
+ return 0;
}
-EXPORT_SYMBOL_GPL(probe_kernel_read);
+EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
/**
- * probe_user_read(): safely attempt to read from a user-space location
- * @dst: pointer to the buffer that shall take the data
- * @src: address to read from. This must be a user address.
- * @size: size of the data chunk
- *
- * Safely read from user address @src to the buffer at @dst. If a kernel fault
- * happens, handle that and return -EFAULT.
- */
-
-long __weak probe_user_read(void *dst, const void __user *src, size_t size)
- __attribute__((alias("__probe_user_read")));
-
-long __probe_user_read(void *dst, const void __user *src, size_t size)
-{
- long ret = -EFAULT;
- mm_segment_t old_fs = get_fs();
-
- set_fs(USER_DS);
- if (access_ok(VERIFY_READ, src, size))
- ret = probe_read_common(dst, src, size);
- set_fs(old_fs);
-
- return ret;
-}
-EXPORT_SYMBOL_GPL(probe_user_read);
-
-/**
- * probe_kernel_write(): safely attempt to write to a location
+ * copy_to_kernel_nofault(): safely attempt to write to a location
* @dst: address to write to
* @src: pointer to the data that shall be written
* @size: size of the data chunk
@@ -96,52 +132,25 @@
* Safely write to address @dst from the buffer at @src. If a kernel fault
* happens, handle that and return -EFAULT.
*/
-
-long __weak probe_kernel_write(void *dst, const void *src, size_t size)
- __attribute__((alias("__probe_kernel_write")));
-
-long __probe_kernel_write(void *dst, const void *src, size_t size)
+long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
{
long ret;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
- ret = probe_write_common((__force void __user *)dst, src, size);
+ pagefault_disable();
+ ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
+ pagefault_enable();
set_fs(old_fs);
- return ret;
+ if (ret)
+ return -EFAULT;
+ return 0;
}
-EXPORT_SYMBOL_GPL(probe_kernel_write);
/**
- * probe_user_write(): safely attempt to write to a user-space location
- * @dst: address to write to
- * @src: pointer to the data that shall be written
- * @size: size of the data chunk
- *
- * Safely write to address @dst from the buffer at @src. If a kernel fault
- * happens, handle that and return -EFAULT.
- */
-
-long __weak probe_user_write(void __user *dst, const void *src, size_t size)
- __attribute__((alias("__probe_user_write")));
-
-long __probe_user_write(void __user *dst, const void *src, size_t size)
-{
- long ret = -EFAULT;
- mm_segment_t old_fs = get_fs();
-
- set_fs(USER_DS);
- if (access_ok(VERIFY_WRITE, dst, size))
- ret = probe_write_common(dst, src, size);
- set_fs(old_fs);
-
- return ret;
-}
-EXPORT_SYMBOL_GPL(probe_user_write);
-
-/**
- * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address.
+ * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe
+ * address.
* @dst: Destination address, in kernel space. This buffer must be at
* least @count bytes long.
* @unsafe_addr: Unsafe address.
@@ -151,13 +160,14 @@
*
* On success, returns the length of the string INCLUDING the trailing NUL.
*
- * If access fails, returns -EFAULT (some data may have been copied
- * and the trailing NUL added).
+ * If access fails, returns -EFAULT (some data may have been copied and the
+ * trailing NUL added). If @unsafe_addr is not a valid kernel address, return
+ * -ERANGE.
*
* If @count is smaller than the length of the string, copies @count-1 bytes,
* sets the last byte of @dst buffer to NUL and returns @count.
*/
-long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
+long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
{
mm_segment_t old_fs = get_fs();
const void *src = unsafe_addr;
@@ -165,6 +175,8 @@
if (unlikely(count <= 0))
return 0;
+ if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))
+ return -ERANGE;
set_fs(KERNEL_DS);
pagefault_disable();
@@ -179,9 +191,64 @@
return ret ? -EFAULT : src - unsafe_addr;
}
+#endif /* HAVE_GET_KERNEL_NOFAULT */
/**
- * strncpy_from_unsafe_user: - Copy a NUL terminated string from unsafe user
+ * copy_from_user_nofault(): safely attempt to read from a user-space location
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from. This must be a user address.
+ * @size: size of the data chunk
+ *
+ * Safely read from user address @src to the buffer at @dst. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+long copy_from_user_nofault(void *dst, const void __user *src, size_t size)
+{
+ long ret = -EFAULT;
+ mm_segment_t old_fs = force_uaccess_begin();
+
+ if (access_ok(src, size)) {
+ pagefault_disable();
+ ret = __copy_from_user_inatomic(dst, src, size);
+ pagefault_enable();
+ }
+ force_uaccess_end(old_fs);
+
+ if (ret)
+ return -EFAULT;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(copy_from_user_nofault);
+
+/**
+ * copy_to_user_nofault(): safely attempt to write to a user-space location
+ * @dst: address to write to
+ * @src: pointer to the data that shall be written
+ * @size: size of the data chunk
+ *
+ * Safely write to address @dst from the buffer at @src. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+long copy_to_user_nofault(void __user *dst, const void *src, size_t size)
+{
+ long ret = -EFAULT;
+ mm_segment_t old_fs = force_uaccess_begin();
+
+ if (access_ok(dst, size)) {
+ pagefault_disable();
+ ret = __copy_to_user_inatomic(dst, src, size);
+ pagefault_enable();
+ }
+ force_uaccess_end(old_fs);
+
+ if (ret)
+ return -EFAULT;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(copy_to_user_nofault);
+
+/**
+ * strncpy_from_user_nofault: - Copy a NUL terminated string from unsafe user
* address.
* @dst: Destination address, in kernel space. This buffer must be at
* least @count bytes long.
@@ -198,20 +265,20 @@
* If @count is smaller than the length of the string, copies @count-1 bytes,
* sets the last byte of @dst buffer to NUL and returns @count.
*/
-long strncpy_from_unsafe_user(char *dst, const void __user *unsafe_addr,
+long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
long count)
{
- mm_segment_t old_fs = get_fs();
+ mm_segment_t old_fs;
long ret;
if (unlikely(count <= 0))
return 0;
- set_fs(USER_DS);
+ old_fs = force_uaccess_begin();
pagefault_disable();
ret = strncpy_from_user(dst, unsafe_addr, count);
pagefault_enable();
- set_fs(old_fs);
+ force_uaccess_end(old_fs);
if (ret >= count) {
ret = count;
@@ -224,7 +291,7 @@
}
/**
- * strnlen_unsafe_user: - Get the size of a user string INCLUDING final NUL.
+ * strnlen_user_nofault: - Get the size of a user string INCLUDING final NUL.
* @unsafe_addr: The string to measure.
* @count: Maximum count (including NUL)
*
@@ -239,16 +306,16 @@
* Unlike strnlen_user, this can be used from IRQ handler etc. because
* it disables pagefaults.
*/
-long strnlen_unsafe_user(const void __user *unsafe_addr, long count)
+long strnlen_user_nofault(const void __user *unsafe_addr, long count)
{
- mm_segment_t old_fs = get_fs();
+ mm_segment_t old_fs;
int ret;
- set_fs(USER_DS);
+ old_fs = force_uaccess_begin();
pagefault_disable();
ret = strnlen_user(unsafe_addr, count);
pagefault_enable();
- set_fs(old_fs);
+ force_uaccess_end(old_fs);
return ret;
}
--
Gitblit v1.6.2