Re: [PATCH v2] s390: ensure that syscall arguments are properly masked on s390
On Mon, Jun 27, 2016 at 10:34 AM, Paul Moore <pmoore(a)redhat.com> wrote:
From: Paul Moore <paul(a)paul-moore.com>
When executing s390 code on s390x the syscall arguments are not
properly masked, leading to some malformed audit records.
Signed-off-by: Paul Moore <paul(a)paul-moore.com>
---
arch/s390/kernel/ptrace.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
The only change between v2 and the original patch is the use of
is_compat_task() instead of the #ifdef, as suggested by Heiko. Like
before, I've added this patch to the audit#next branch; I think we
have sorted all the feedback, but if any objections remain please let
me know.
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 49b1c13..defc0dc 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -822,6 +822,7 @@ 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;
+ unsigned long mask = -1UL;
/* Do the secure computing check first. */
if (secure_computing()) {
@@ -849,9 +850,12 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->gprs[2]);
- audit_syscall_entry(regs->gprs[2], regs->orig_gpr2,
- regs->gprs[3], regs->gprs[4],
- regs->gprs[5]);
+ if (is_compat_task())
+ mask = 0xffffffff;
+
+ audit_syscall_entry(regs->gprs[2], regs->orig_gpr2 & mask,
+ regs->gprs[3] & mask, regs->gprs[4] & mask,
+ regs->gprs[5] & mask);
out:
return ret ?: regs->gprs[2];
}
--
paul moore
security @ redhat