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authorAndrea Arcangeli <andrea@cpushare.com>2005-09-09 13:01:51 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-09 13:57:30 -0700
commit4c7fc7220f6a3cce9b3f4bd66362176df67df577 (patch)
tree5824a334335dcc283a76ffad6294ed0904364157 /arch/i386
parent4d666d7ada2e14d71d463c85b8b5ef2e2e6723f2 (diff)
[PATCH] i386: seccomp fix for auditing/ptrace
This is the same issue as ppc64 before, when returning to userland we shouldn't re-compute the seccomp check or the task could be killed during sigreturn when orig_eax is overwritten by the sigreturn syscall. This was found by Roland. This was harmless from a security standpoint, but some i686 users reported failures with auditing enabled system wide (some distro surprisingly makes it the default) and I reproduced it too by keeping the whole workload under strace -f. Patch is tested and works for me under strace -f. nobody@athlon:~/cpushare> strace -o /tmp/o -f python seccomp_test.py make: Nothing to be done for `seccomp_test'. Starting computing some malicious bytecode init load start stop receive_data failure kill exit_code 0 signal 9 The malicious bytecode has been killed successfully by seccomp Starting computing some safe bytecode init load start stop 174 counts kill exit_code 0 signal 0 The seccomp_test.py completed successfully, thank you for testing. (akpm: collaterally cleaned up a bit of do_syscall_trace() too) Signed-off-by: Andrea Arcangeli <andrea@cpushare.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/kernel/ptrace.c22
1 files changed, 14 insertions, 8 deletions
diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c
index 340980203b0..7b6368bf897 100644
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -694,17 +694,22 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
__attribute__((regparm(3)))
int do_syscall_trace(struct pt_regs *regs, int entryexit)
{
- int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU), ret = 0;
- /* With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP for syscall
- * interception. */
+ int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU);
+ /*
+ * With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP for syscall
+ * interception
+ */
int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP);
+ int ret = 0;
/* do the secure computing check first */
- secure_computing(regs->orig_eax);
+ if (!entryexit)
+ secure_computing(regs->orig_eax);
if (unlikely(current->audit_context)) {
if (entryexit)
- audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
+ audit_syscall_exit(current, AUDITSC_RESULT(regs->eax),
+ regs->eax);
/* Debug traps, when using PTRACE_SINGLESTEP, must be sent only
* on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is
* not used, entry.S will call us only on syscall exit, not
@@ -738,7 +743,7 @@ int do_syscall_trace(struct pt_regs *regs, int entryexit)
/* the 0x80 provides a way for the tracing parent to distinguish
between a syscall stop and SIGTRAP delivery */
/* Note that the debugger could change the result of test_thread_flag!*/
- ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
+ ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ? 0x80:0));
/*
* this isn't the same as continuing with a signal, but it will do
@@ -750,7 +755,7 @@ int do_syscall_trace(struct pt_regs *regs, int entryexit)
current->exit_code = 0;
}
ret = is_sysemu;
- out:
+out:
if (unlikely(current->audit_context) && !entryexit)
audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax,
regs->ebx, regs->ecx, regs->edx, regs->esi);
@@ -759,6 +764,7 @@ int do_syscall_trace(struct pt_regs *regs, int entryexit)
regs->orig_eax = -1; /* force skip of syscall restarting */
if (unlikely(current->audit_context))
- audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
+ audit_syscall_exit(current, AUDITSC_RESULT(regs->eax),
+ regs->eax);
return 1;
}