Close the hole where ptrace can change a syscall out from under seccomp.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: linux-s390@xxxxxxxxxxxxxxx
---
arch/s390/kernel/ptrace.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index c238e9958c2a..cea17010448f 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -821,15 +821,6 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
- long ret = 0;
-
- /* Do the secure computing check first. */
- if (secure_computing(NULL)) {
- /* seccomp failures shouldn't expose any additional code. */
- ret = -1;
- goto out;
- }
-
/*
* The sysc_tracesys code in entry.S stored the system
* call number to gprs[2].
@@ -843,7 +834,13 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
* the system call and the system call restart handling.
*/
clear_pt_regs_flag(regs, PIF_SYSCALL);
- ret = -1;
+ return -1;
+ }
+
+ /* Do the secure computing check after ptrace. */
+ if (secure_computing(NULL)) {
+ /* seccomp failures shouldn't expose any additional code. */
+ return -1;
}
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
@@ -852,8 +849,8 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
audit_syscall_entry(regs->gprs[2], regs->orig_gpr2,
regs->gprs[3], regs->gprs[4],
regs->gprs[5]);
-out:
- return ret ?: regs->gprs[2];
+
+ return regs->gprs[2];
}
asmlinkage void do_syscall_trace_exit(struct pt_regs *regs)
--
2.7.4
