Close the hole where ptrace can change a syscall out from under seccomp.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
---
arch/arm/kernel/ptrace.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index ad5e90ab165c..dc7b372872ff 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -932,18 +932,19 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
{
current_thread_info()->syscall = scno;
- /* Do the secure computing check first; failures should be fast. */
+ if (test_thread_flag(TIF_SYSCALL_TRACE))
+ tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
+
+ /* Do seccomp after ptrace; syscall may have changed. */
#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
if (secure_computing(NULL) == -1)
return -1;
#else
/* XXX: remove this once OABI gets fixed */
- secure_computing_strict(scno);
+ secure_computing_strict(current_thread_info()->syscall);
#endif
- if (test_thread_flag(TIF_SYSCALL_TRACE))
- tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
-
+ /* Tracer or seccomp may have changed syscall. */
scno = current_thread_info()->syscall;
if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
--
2.7.4
