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    Contents of /trunk/kernel26-magellan/patches-2.6.16-r10/0103-2.6.16.12-vm86-call-audit_syscall_exit.patch

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    Revision 70 - (show annotations) (download)
    Thu May 11 19:09:22 2006 UTC (18 years ago) by niro
    File size: 3589 byte(s) 
    import
    1 From: Jason Baron <jbaron@redhat.com>
    2 Date: Tue, 31 Jan 2006 21:56:28 +0000 (-0500)
    3 Subject: [PATCH] make vm86 call audit_syscall_exit
    4 X-Git-Url: http://www.kernel.org/git/?p=linux/kernel/git/stable/linux-2.6.16.y.git;a=commitdiff;h=f38f300d4a0698791bb11294903702ddb1c4e9d8
    5
    6 [PATCH] make vm86 call audit_syscall_exit
    7
    8 hi,
    9
    10 The motivation behind the patch below was to address messages in
    11 /var/log/messages such as:
    12
    13 Jan 31 10:54:15 mets kernel: audit(:0): major=252 name_count=0: freeing
    14 multiple contexts (1)
    15 Jan 31 10:54:15 mets kernel: audit(:0): major=113 name_count=0: freeing
    16 multiple contexts (2)
    17
    18 I can reproduce by running 'get-edid' from:
    19 http://john.fremlin.de/programs/linux/read-edid/.
    20
    21 These messages come about in the log b/c the vm86 calls do not exit via
    22 the normal system call exit paths and thus do not call
    23 'audit_syscall_exit'. The next system call will then free the context for
    24 itself and for the vm86 context, thus generating the above messages. This
    25 patch addresses the issue by simply adding a call to 'audit_syscall_exit'
    26 from the vm86 code.
    27
    28 Besides fixing the above error messages the patch also now allows vm86
    29 system calls to become auditable. This is useful since strace does not
    30 appear to properly record the return values from sys_vm86.
    31
    32 I think this patch is also a step in the right direction in terms of
    33 cleaning up some core auditing code. If we can correct any other paths
    34 that do not properly call the audit exit and entries points, then we can
    35 also eliminate the notion of context chaining.
    36
    37 I've tested this patch by verifying that the log messages no longer
    38 appear, and that the audit records for sys_vm86 appear to be correct.
    39 Also, 'read_edid' produces itentical output.
    40
    41 thanks,
    42
    43 -Jason
    44
    45 Signed-off-by: Jason Baron <jbaron@redhat.com>
    46 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    47 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    48 ---
    49
    50 --- a/arch/i386/kernel/vm86.c
    51 +++ b/arch/i386/kernel/vm86.c
    52 @@ -43,6 +43,7 @@
    53 #include <linux/smp_lock.h>
    54 #include <linux/highmem.h>
    55 #include <linux/ptrace.h>
    56 +#include <linux/audit.h>
    57
    58 #include <asm/uaccess.h>
    59 #include <asm/io.h>
    60 @@ -252,6 +253,7 @@ out:
    61 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
    62 {
    63 struct tss_struct *tss;
    64 + long eax;
    65 /*
    66 * make sure the vm86() system call doesn't try to do anything silly
    67 */
    68 @@ -305,13 +307,19 @@ static void do_sys_vm86(struct kernel_vm
    69 tsk->thread.screen_bitmap = info->screen_bitmap;
    70 if (info->flags & VM86_SCREEN_BITMAP)
    71 mark_screen_rdonly(tsk->mm);
    72 + __asm__ __volatile__("xorl %eax,%eax; movl %eax,%fs; movl %eax,%gs\n\t");
    73 + __asm__ __volatile__("movl %%eax, %0\n" :"=r"(eax));
    74 +
    75 + /*call audit_syscall_exit since we do not exit via the normal paths */
    76 + if (unlikely(current->audit_context))
    77 + audit_syscall_exit(current, AUDITSC_RESULT(eax), eax);
    78 +
    79 __asm__ __volatile__(
    80 - "xorl %%eax,%%eax; movl %%eax,%%fs; movl %%eax,%%gs\n\t"
    81 "movl %0,%%esp\n\t"
    82 "movl %1,%%ebp\n\t"
    83 "jmp resume_userspace"
    84 : /* no outputs */
    85 - :"r" (&info->regs), "r" (task_thread_info(tsk)) : "ax");
    86 + :"r" (&info->regs), "r" (task_thread_info(tsk)));
    87 /* we never return here */
    88 }
    89
    90 --- a/kernel/auditsc.c
    91 +++ b/kernel/auditsc.c
    92 @@ -966,11 +966,6 @@ void audit_syscall_entry(struct task_str
    93 if (context->in_syscall) {
    94 struct audit_context *newctx;
    95
    96 -#if defined(__NR_vm86) && defined(__NR_vm86old)
    97 - /* vm86 mode should only be entered once */
    98 - if (major == __NR_vm86 || major == __NR_vm86old)
    99 - return;
    100 -#endif
    101 #if AUDIT_DEBUG
    102 printk(KERN_ERR
    103 "audit(:%d) pid=%d in syscall=%d;"