On Thu, Dec 6, 2018 at 3:50 PM Kees Cook keescook@chromium.org wrote:

Commit f149b3155744 ("signal: Never allocate siginfo for SIGKILL or SIGSTOP") means that the seccomp selftest cannot check si_pid under SIGSTOP anymore. Since it's believed[1] there are no other userspace things depending on the old behavior, this removes the behavioral check in the selftest, since it's more a "extra" sanity check (which turns out, maybe, not to have been useful to test).

[1] https://lkml.kernel.org/r/CAGXu5jJaZAOzP1qFz66tYrtbuywqb+UN2SOA1VLHpCCOiYvYe...

Reported-by: Tycho Andersen tycho@tycho.ws Suggested-by: Eric W. Biederman ebiederm@xmission.com Signed-off-by: Kees Cook keescook@chromium.org

---

Shuah, can you make sure that Linus gets this before v4.20 is released? Thanks!

Ping. Shuah, can you get this to Linus (or should I send it directly?)

Thanks!

-Kees

---

tools/testing/selftests/seccomp/seccomp_bpf.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index e1473234968d..c9a2abf8be1b 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -2731,9 +2731,14 @@ TEST(syscall_restart) ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0)); ASSERT_EQ(true, WIFSTOPPED(status)); ASSERT_EQ(SIGSTOP, WSTOPSIG(status));

•   /* Verify signal delivery came from parent now. */
    ASSERT_EQ(0, ptrace(PTRACE_GETSIGINFO, child_pid, NULL, &info));
  

•   EXPECT_EQ(getpid(), info.si_pid);
  

•   /*
  

•    * There is no siginfo on SIGSTOP any more, so we can't verify
  

•    * signal delivery came from parent now (getpid() == info.si_pid).
  

•    * https://lkml.kernel.org/r/CAGXu5jJaZAOzP1qFz66tYrtbuywqb+UN2SOA1VLHpCCOiYvYeg@mail.gmail.com
  

•    * At least verify the SIGSTOP via PTRACE_GETSIGINFO.
  

•    */
  

•   EXPECT_EQ(SIGSTOP, info.si_signo);
  
    /* Restart nanosleep with SIGCONT, which triggers restart_syscall. */
    ASSERT_EQ(0, kill(child_pid, SIGCONT));
  

-- 2.17.1

-- Kees Cook