On 19/03/2021 18:56, Kees Cook wrote: > On Tue, Mar 16, 2021 at 09:42:50PM +0100, Mickaël Salaün wrote: >> From: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> >> >> Test all Landlock system calls, ptrace hooks semantic and filesystem >> access-control with multiple layouts. >> >> Test coverage for security/landlock/ is 93.6% of lines. The code not >> covered only deals with internal kernel errors (e.g. memory allocation) >> and race conditions. >> >> Cc: James Morris <jmorris@xxxxxxxxx> >> Cc: Jann Horn <jannh@xxxxxxxxxx> >> Cc: Kees Cook <keescook@xxxxxxxxxxxx> >> Cc: Serge E. Hallyn <serge@xxxxxxxxxx> >> Cc: Shuah Khan <shuah@xxxxxxxxxx> >> Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> >> Reviewed-by: Vincent Dagonneau <vincent.dagonneau@xxxxxxxxxxx> >> Link: https://lore.kernel.org/r/20210316204252.427806-11-mic@xxxxxxxxxxx > > This is terrific. I love the coverage. How did you measure this, BTW? I used gcov: https://www.kernel.org/doc/html/latest/dev-tools/gcov.html > To increase it into memory allocation failures, have you tried > allocation fault injection: > https://www.kernel.org/doc/html/latest/fault-injection/fault-injection.html Yes, it is used by syzkaller, but I don't know how to extract this specific coverage. > >> [...] >> +TEST(inconsistent_attr) { >> + const long page_size = sysconf(_SC_PAGESIZE); >> + char *const buf = malloc(page_size + 1); >> + struct landlock_ruleset_attr *const ruleset_attr = (void *)buf; >> + >> + ASSERT_NE(NULL, buf); >> + >> + /* Checks copy_from_user(). */ >> + ASSERT_EQ(-1, landlock_create_ruleset(ruleset_attr, 0, 0)); >> + /* The size if less than sizeof(struct landlock_attr_enforce). */ >> + ASSERT_EQ(EINVAL, errno); >> + ASSERT_EQ(-1, landlock_create_ruleset(ruleset_attr, 1, 0)); >> + ASSERT_EQ(EINVAL, errno); > > Almost everywhere you're using ASSERT instead of EXPECT. Is this correct > (in the sense than as soon as an ASSERT fails the rest of the test is > skipped)? I do see you using EXPECT is some places, but I figured I'd > ask about the intention here. I intentionally use ASSERT as much as possible, but I use EXPECT when an error could block a test or when it could stop a cleanup (i.e. teardown). > >> +/* >> + * TEST_F_FORK() is useful when a test drop privileges but the corresponding >> + * FIXTURE_TEARDOWN() requires them (e.g. to remove files from a directory >> + * where write actions are denied). For convenience, FIXTURE_TEARDOWN() is >> + * also called when the test failed, but not when FIXTURE_SETUP() failed. For >> + * this to be possible, we must not call abort() but instead exit smoothly >> + * (hence the step print). >> + */ > > Hm, interesting. I think this should be extracted into a separate patch > and added to the test harness proper. I agree, but it may require some modifications to fit nicely in kselftest_harness.h . For now, it works well for my use case. I'll send patches once Landlock is merged. In fact, I already made kselftest_harness.h available for other users than seccomp. ;) > > Could this be solved with TEARDOWN being called on SETUP failure? The goal of this helper is to still be able to call TEARDOWN when TEST failed, not SETUP. > >> +#define TEST_F_FORK(fixture_name, test_name) \ >> + static void fixture_name##_##test_name##_child( \ >> + struct __test_metadata *_metadata, \ >> + FIXTURE_DATA(fixture_name) *self, \ >> + const FIXTURE_VARIANT(fixture_name) *variant); \ >> + TEST_F(fixture_name, test_name) \ >> + { \ >> + int status; \ >> + const pid_t child = fork(); \ >> + if (child < 0) \ >> + abort(); \ >> + if (child == 0) { \ >> + _metadata->no_print = 1; \ >> + fixture_name##_##test_name##_child(_metadata, self, variant); \ >> + if (_metadata->skip) \ >> + _exit(255); \ >> + if (_metadata->passed) \ >> + _exit(0); \ >> + _exit(_metadata->step); \ >> + } \ >> + if (child != waitpid(child, &status, 0)) \ >> + abort(); \ >> + if (WIFSIGNALED(status) || !WIFEXITED(status)) { \ >> + _metadata->passed = 0; \ >> + _metadata->step = 1; \ >> + return; \ >> + } \ >> + switch (WEXITSTATUS(status)) { \ >> + case 0: \ >> + _metadata->passed = 1; \ >> + break; \ >> + case 255: \ >> + _metadata->passed = 1; \ >> + _metadata->skip = 1; \ >> + break; \ >> + default: \ >> + _metadata->passed = 0; \ >> + _metadata->step = WEXITSTATUS(status); \ >> + break; \ >> + } \ >> + } \ > > This looks like a subset of __wait_for_test()? Could __TEST_F_IMPL() be > updated instead to do this? (Though the fork overhead might not be great > for everyone.) Yes, it will probably be my approach to update kselftest_harness.h .
