This is a note to let you know that I've just added the patch titled
arm64: ptrace: Fix seccomp of traced syscall -1 (NO_SYSCALL)
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-ptrace-fix-seccomp-of-traced-syscall-1-no_syscall.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From df84fe94708985cdfb78a83148322bcd0a699472 Mon Sep 17 00:00:00 2001
From: Timothy E Baldwin <T.E.Baldwin99@xxxxxxxxxxxxxxxxxxx>
Date: Sat, 16 Jan 2021 15:18:54 +0000
Subject: arm64: ptrace: Fix seccomp of traced syscall -1 (NO_SYSCALL)
From: Timothy E Baldwin <T.E.Baldwin99@xxxxxxxxxxxxxxxxxxx>
commit df84fe94708985cdfb78a83148322bcd0a699472 upstream.
Since commit f086f67485c5 ("arm64: ptrace: add support for syscall
emulation"), if system call number -1 is called and the process is being
traced with PTRACE_SYSCALL, for example by strace, the seccomp check is
skipped and -ENOSYS is returned unconditionally (unless altered by the
tracer) rather than carrying out action specified in the seccomp filter.
The consequence of this is that it is not possible to reliably strace
a seccomp based implementation of a foreign system call interface in
which r7/x8 is permitted to be -1 on entry to a system call.
Also trace_sys_enter and audit_syscall_entry are skipped if a system
call is skipped.
Fix by removing the in_syscall(regs) check restoring the previous
behaviour which is like AArch32, x86 (which uses generic code) and
everything else.
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Catalin Marinas<catalin.marinas@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: f086f67485c5 ("arm64: ptrace: add support for syscall emulation")
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Tested-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: Timothy E Baldwin <T.E.Baldwin99@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/90edd33b-6353-1228-791f-0336d94d5f8c@xxxxxxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/ptrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -1796,7 +1796,7 @@ int syscall_trace_enter(struct pt_regs *
if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
- if (!in_syscall(regs) || (flags & _TIF_SYSCALL_EMU))
+ if (flags & _TIF_SYSCALL_EMU)
return NO_SYSCALL;
}
Patches currently in stable-queue which might be from T.E.Baldwin99@xxxxxxxxxxxxxxxxxxx are
queue-5.11/arm64-ptrace-fix-seccomp-of-traced-syscall-1-no_syscall.patch
