From f9004dbfff8a3fbbd7e2a88c8a4327c7f2f8e5b2 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 31 Jan 2024 01:04:47 +0000
Subject: [PATCH] add driver 5G
---
kernel/arch/x86/kernel/ioport.c | 219 +++++++++++++++++++++++++++++++++++++-----------------
1 files changed, 148 insertions(+), 71 deletions(-)
diff --git a/kernel/arch/x86/kernel/ioport.c b/kernel/arch/x86/kernel/ioport.c
index 0fe1c87..e2fab3c 100644
--- a/kernel/arch/x86/kernel/ioport.c
+++ b/kernel/arch/x86/kernel/ioport.c
@@ -3,35 +3,75 @@
* This contains the io-permission bitmap code - written by obz, with changes
* by Linus. 32/64 bits code unification by Miguel Botón.
*/
-
-#include <linux/sched.h>
-#include <linux/sched/task_stack.h>
-#include <linux/kernel.h>
#include <linux/capability.h>
-#include <linux/errno.h>
-#include <linux/types.h>
-#include <linux/ioport.h>
-#include <linux/smp.h>
-#include <linux/stddef.h>
-#include <linux/slab.h>
-#include <linux/thread_info.h>
+#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/bitmap.h>
-#include <asm/syscalls.h>
+#include <linux/ioport.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include <asm/io_bitmap.h>
#include <asm/desc.h>
+#include <asm/syscalls.h>
+
+#ifdef CONFIG_X86_IOPL_IOPERM
+
+static atomic64_t io_bitmap_sequence;
+
+void io_bitmap_share(struct task_struct *tsk)
+{
+ /* Can be NULL when current->thread.iopl_emul == 3 */
+ if (current->thread.io_bitmap) {
+ /*
+ * Take a refcount on current's bitmap. It can be used by
+ * both tasks as long as none of them changes the bitmap.
+ */
+ refcount_inc(¤t->thread.io_bitmap->refcnt);
+ tsk->thread.io_bitmap = current->thread.io_bitmap;
+ }
+ set_tsk_thread_flag(tsk, TIF_IO_BITMAP);
+}
+
+static void task_update_io_bitmap(struct task_struct *tsk)
+{
+ struct thread_struct *t = &tsk->thread;
+
+ if (t->iopl_emul == 3 || t->io_bitmap) {
+ /* TSS update is handled on exit to user space */
+ set_tsk_thread_flag(tsk, TIF_IO_BITMAP);
+ } else {
+ clear_tsk_thread_flag(tsk, TIF_IO_BITMAP);
+ /* Invalidate TSS */
+ preempt_disable();
+ tss_update_io_bitmap();
+ preempt_enable();
+ }
+}
+
+void io_bitmap_exit(struct task_struct *tsk)
+{
+ struct io_bitmap *iobm = tsk->thread.io_bitmap;
+
+ tsk->thread.io_bitmap = NULL;
+ task_update_io_bitmap(tsk);
+ if (iobm && refcount_dec_and_test(&iobm->refcnt))
+ kfree(iobm);
+}
/*
- * this changes the io permissions bitmap in the current task.
+ * This changes the io permissions bitmap in the current task.
*/
long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
{
struct thread_struct *t = ¤t->thread;
- struct tss_struct *tss;
- unsigned int i, max_long, bytes, bytes_updated;
+ unsigned int i, max_long;
+ struct io_bitmap *iobm;
if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
return -EINVAL;
- if (turn_on && !capable(CAP_SYS_RAWIO))
+ if (turn_on && (!capable(CAP_SYS_RAWIO) ||
+ security_locked_down(LOCKDOWN_IOPORT)))
return -EPERM;
/*
@@ -39,59 +79,72 @@
* IO bitmap up. ioperm() is much less timing critical than clone(),
* this is why we delay this operation until now:
*/
- if (!t->io_bitmap_ptr) {
- unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
-
- if (!bitmap)
+ iobm = t->io_bitmap;
+ if (!iobm) {
+ /* No point to allocate a bitmap just to clear permissions */
+ if (!turn_on)
+ return 0;
+ iobm = kmalloc(sizeof(*iobm), GFP_KERNEL);
+ if (!iobm)
return -ENOMEM;
- memset(bitmap, 0xff, IO_BITMAP_BYTES);
- t->io_bitmap_ptr = bitmap;
- set_thread_flag(TIF_IO_BITMAP);
-
- /*
- * Now that we have an IO bitmap, we need our TSS limit to be
- * correct. It's fine if we are preempted after doing this:
- * with TIF_IO_BITMAP set, context switches will keep our TSS
- * limit correct.
- */
- preempt_disable();
- refresh_tss_limit();
- preempt_enable();
+ memset(iobm->bitmap, 0xff, sizeof(iobm->bitmap));
+ refcount_set(&iobm->refcnt, 1);
}
/*
- * do it in the per-thread copy and in the TSS ...
- *
- * Disable preemption via get_cpu() - we must not switch away
- * because the ->io_bitmap_max value must match the bitmap
- * contents:
+ * If the bitmap is not shared, then nothing can take a refcount as
+ * current can obviously not fork at the same time. If it's shared
+ * duplicate it and drop the refcount on the original one.
*/
- tss = &per_cpu(cpu_tss_rw, get_cpu());
+ if (refcount_read(&iobm->refcnt) > 1) {
+ iobm = kmemdup(iobm, sizeof(*iobm), GFP_KERNEL);
+ if (!iobm)
+ return -ENOMEM;
+ refcount_set(&iobm->refcnt, 1);
+ io_bitmap_exit(current);
+ }
+ /*
+ * Store the bitmap pointer (might be the same if the task already
+ * head one). Must be done here so freeing the bitmap when all
+ * permissions are dropped has the pointer set up.
+ */
+ t->io_bitmap = iobm;
+ /* Mark it active for context switching and exit to user mode */
+ set_thread_flag(TIF_IO_BITMAP);
+
+ /*
+ * Update the tasks bitmap. The update of the TSS bitmap happens on
+ * exit to user mode. So this needs no protection.
+ */
if (turn_on)
- bitmap_clear(t->io_bitmap_ptr, from, num);
+ bitmap_clear(iobm->bitmap, from, num);
else
- bitmap_set(t->io_bitmap_ptr, from, num);
+ bitmap_set(iobm->bitmap, from, num);
/*
* Search for a (possibly new) maximum. This is simple and stupid,
* to keep it obviously correct:
*/
- max_long = 0;
- for (i = 0; i < IO_BITMAP_LONGS; i++)
- if (t->io_bitmap_ptr[i] != ~0UL)
+ max_long = UINT_MAX;
+ for (i = 0; i < IO_BITMAP_LONGS; i++) {
+ if (iobm->bitmap[i] != ~0UL)
max_long = i;
+ }
+ /* All permissions dropped? */
+ if (max_long == UINT_MAX) {
+ io_bitmap_exit(current);
+ return 0;
+ }
- bytes = (max_long + 1) * sizeof(unsigned long);
- bytes_updated = max(bytes, t->io_bitmap_max);
+ iobm->max = (max_long + 1) * sizeof(unsigned long);
- t->io_bitmap_max = bytes;
-
- /* Update the TSS: */
- memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
-
- put_cpu();
+ /*
+ * Update the sequence number to force a TSS update on return to
+ * user mode.
+ */
+ iobm->sequence = atomic64_add_return(1, &io_bitmap_sequence);
return 0;
}
@@ -102,37 +155,61 @@
}
/*
- * sys_iopl has to be used when you want to access the IO ports
- * beyond the 0x3ff range: to get the full 65536 ports bitmapped
- * you'd need 8kB of bitmaps/process, which is a bit excessive.
+ * The sys_iopl functionality depends on the level argument, which if
+ * granted for the task is used to enable access to all 65536 I/O ports.
*
- * Here we just change the flags value on the stack: we allow
- * only the super-user to do it. This depends on the stack-layout
- * on system-call entry - see also fork() and the signal handling
- * code.
+ * This does not use the IOPL mechanism provided by the CPU as that would
+ * also allow the user space task to use the CLI/STI instructions.
+ *
+ * Disabling interrupts in a user space task is dangerous as it might lock
+ * up the machine and the semantics vs. syscalls and exceptions is
+ * undefined.
+ *
+ * Setting IOPL to level 0-2 is disabling I/O permissions. Level 3
+ * 3 enables them.
+ *
+ * IOPL is strictly per thread and inherited on fork.
*/
SYSCALL_DEFINE1(iopl, unsigned int, level)
{
- struct pt_regs *regs = current_pt_regs();
struct thread_struct *t = ¤t->thread;
-
- /*
- * Careful: the IOPL bits in regs->flags are undefined under Xen PV
- * and changing them has no effect.
- */
- unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT;
+ unsigned int old;
if (level > 3)
return -EINVAL;
+
+ old = t->iopl_emul;
+
+ /* No point in going further if nothing changes */
+ if (level == old)
+ return 0;
+
/* Trying to gain more privileges? */
if (level > old) {
- if (!capable(CAP_SYS_RAWIO))
+ if (!capable(CAP_SYS_RAWIO) ||
+ security_locked_down(LOCKDOWN_IOPORT))
return -EPERM;
}
- regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |
- (level << X86_EFLAGS_IOPL_BIT);
- t->iopl = level << X86_EFLAGS_IOPL_BIT;
- set_iopl_mask(t->iopl);
+
+ t->iopl_emul = level;
+ task_update_io_bitmap(current);
return 0;
}
+
+#else /* CONFIG_X86_IOPL_IOPERM */
+
+long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
+{
+ return -ENOSYS;
+}
+SYSCALL_DEFINE3(ioperm, unsigned long, from, unsigned long, num, int, turn_on)
+{
+ return -ENOSYS;
+}
+
+SYSCALL_DEFINE1(iopl, unsigned int, level)
+{
+ return -ENOSYS;
+}
+#endif
--
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