On Sat, Jan 26, 2019 at 3:55 AM Colin King colin.king@canonical.com wrote:

From: Colin Ian King colin.king@canonical.com

The error return being placed in regs.SYSCALL_RET is currently positive and this is causing test failures on s390x. The return value should be -EPERM rather than EPERM otherwise a failure is not detected and errno is not set accordingly on s390x.

Ah, hm, interesting. Yes, the selftest was accidentally encoding the wrong details. However, I think the test for the result is a bit more broken. EPERM is 1, so there isn't even a sanity check that the result is getting passed down (the -1 from syscall won't tell us if the errno actually landed too, so we need to check that with something that isn't EPERM).

Let me send a patch to test on s390...

-Kees

Fixes: a33b2d0359a0 ("selftests/seccomp: Add tests for basic ptrace actions") Signed-off-by: Colin Ian King colin.king@canonical.com

---

V2: remove misplaced Content-Type and Content-Transfer-Encoding fields

---

tools/testing/selftests/seccomp/seccomp_bpf.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index 496a9a8c773a..957344884360 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -1706,7 +1706,7 @@ void change_syscall(struct __test_metadata *_metadata, #ifdef SYSCALL_NUM_RET_SHARE_REG TH_LOG("Can't modify syscall return on this architecture"); #else

•           regs.SYSCALL_RET = EPERM;
  

•           regs.SYSCALL_RET = -EPERM;
  

#endif

#ifdef HAVE_GETREGS @@ -1850,7 +1850,7 @@ TEST_F(TRACE_syscall, ptrace_syscall_dropped) true);

    /* Tracer should skip the open syscall, resulting in EPERM. */

•   EXPECT_SYSCALL_RETURN(EPERM, syscall(__NR_openat));
  

•   EXPECT_SYSCALL_RETURN(-EPERM, syscall(__NR_openat));
  

}

TEST_F(TRACE_syscall, syscall_allowed) @@ -1894,7 +1894,7 @@ TEST_F(TRACE_syscall, syscall_dropped) ASSERT_EQ(0, ret);

    /* gettid has been skipped and an altered return value stored. */

•   EXPECT_SYSCALL_RETURN(EPERM, syscall(__NR_gettid));
  

•   EXPECT_SYSCALL_RETURN(-EPERM, syscall(__NR_gettid));
    EXPECT_NE(self->mytid, syscall(__NR_gettid));
  

}

-- 2.19.1