On Wed, Sep 09, 2020 at 11:53:42PM +1000, Michael Ellerman wrote:
> I can observe the difference between v5.8 and mainline, using the
> raw_syscall trace event and running the seccomp_bpf selftest which turns
> a getpid (39) into a getppid (110).
>
> With v5.8 we see getppid on entry and exit:
>
> seccomp_bpf-1307 [000] .... 22974.874393: sys_enter: NR 110 (7ffff22c46e0, 40a350, 4, fffffffffffff7ab, 7fa6ee0d4010, 0)
> seccomp_bpf-1307 [000] .N.. 22974.874401: sys_exit: NR 110 = 1304
>
> Whereas on mainline we see an enter for getpid and an exit for getppid:
>
> seccomp_bpf-1030 [000] .... 21.806766: sys_enter: NR 39 (7ffe2f6d1ad0, 40a350, 7ffe2f6d1ad0, 0, 0, 407299)
> seccomp_bpf-1030 [000] .... 21.806767: sys_exit: NR 110 = 1027
For my own notes, this is how I reproduced it:
# ./perf-$VER record -e raw_syscalls:sys_enter -e raw_syscalls:sys_exit &
# ./seccomp_bpf
# fg
ctrl-c
# ./perf-$VER script | grep seccomp_bpf | awk '{print $7}' | sort | uniq -c > $VER.log
*repeat*
# diff -u old.log new.log
...
(Is there an easier way to get those results?)
I will go see if I can figure out the best way to correct this.
--
Kees Cook
