There should be no difference between -1 and other negative syscalls while tracing.
Cc: Andy Lutomirski luto@amacapital.net Cc: Will Drewry wad@chromium.org Cc: Will Deacon will@kernel.org Cc: Keno Fischer keno@juliacomputing.com Signed-off-by: Kees Cook keescook@chromium.org --- tools/testing/selftests/seccomp/seccomp_bpf.c | 26 +++++++++++++++++++ 1 file changed, 26 insertions(+)
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index 966dec340ea8..bf6aa06c435c 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -1973,6 +1973,32 @@ FIXTURE_TEARDOWN(TRACE_syscall) teardown_trace_fixture(_metadata, self->tracer); }
+TEST(negative_ENOSYS) +{ + /* Untraced negative syscalls should return ENOSYS. */ + errno = 0; + EXPECT_EQ(-1, syscall(-1)); + EXPECT_EQ(errno, ENOSYS); + errno = 0; + EXPECT_EQ(-1, syscall(-101)); + EXPECT_EQ(errno, ENOSYS); +} + +TEST_F(TRACE_syscall, negative_ENOSYS) +{ + /* + * There should be no difference between an "internal" skip + * and userspace asking for syscall "-1". + */ + errno = 0; + EXPECT_EQ(-1, syscall(-1)); + EXPECT_EQ(errno, ENOSYS); + /* And no difference for "still not valid but not -1". */ + errno = 0; + EXPECT_EQ(-1, syscall(-101)); + EXPECT_EQ(errno, ENOSYS); +} + TEST_F(TRACE_syscall, syscall_allowed) { /* getppid works as expected (no changes). */