selftests/seccomp: Refactor to use fixture variants

Now that the selftest harness has variants, use them to eliminate a
bunch of copy/paste duplication.
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Tested-by: Will Deacon <will@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

tools/testing/selftests/seccomp/seccomp_bpf.c

@@ -1510,6 +1510,7 @@ pid_t setup_trace_fixture(struct __test_metadata *_metadata,
 
 	return tracer_pid;
 }
+
 void teardown_trace_fixture(struct __test_metadata *_metadata,
 			    pid_t tracer)
 {
@@ -1789,7 +1790,7 @@ void change_syscall(struct __test_metadata *_metadata,
 	EXPECT_EQ(0, ret);
 }
 
-void tracer_syscall(struct __test_metadata *_metadata, pid_t tracee,
+void tracer_seccomp(struct __test_metadata *_metadata, pid_t tracee,
 		    int status, void *args)
 {
 	int ret;
@@ -1866,6 +1867,24 @@ FIXTURE(TRACE_syscall) {
 	pid_t tracer, mytid, mypid, parent;
 };
 
+FIXTURE_VARIANT(TRACE_syscall) {
+	/*
+	 * All of the SECCOMP_RET_TRACE behaviors can be tested with either
+	 * SECCOMP_RET_TRACE+PTRACE_CONT or plain ptrace()+PTRACE_SYSCALL.
+	 * This indicates if we should use SECCOMP_RET_TRACE (false), or
+	 * ptrace (true).
+	 */
+	bool use_ptrace;
+};
+
+FIXTURE_VARIANT_ADD(TRACE_syscall, ptrace) {
+	.use_ptrace = true,
+};
+
+FIXTURE_VARIANT_ADD(TRACE_syscall, seccomp) {
+	.use_ptrace = false,
+};
+
 FIXTURE_SETUP(TRACE_syscall)
 {
 	struct sock_filter filter[] = {
@@ -1881,12 +1900,11 @@ FIXTURE_SETUP(TRACE_syscall)
 		BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRACE | 0x1005),
 		BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
 	};
-
-	memset(&self->prog, 0, sizeof(self->prog));
-	self->prog.filter = malloc(sizeof(filter));
-	ASSERT_NE(NULL, self->prog.filter);
-	memcpy(self->prog.filter, filter, sizeof(filter));
-	self->prog.len = (unsigned short)ARRAY_SIZE(filter);
+	struct sock_fprog prog = {
+		.len = (unsigned short)ARRAY_SIZE(filter),
+		.filter = filter,
+	};
+	long ret;
 
 	/* Prepare some testable syscall results. */
 	self->mytid = syscall(__NR_gettid);
@@ -1904,60 +1922,28 @@ FIXTURE_SETUP(TRACE_syscall)
 	ASSERT_NE(self->parent, self->mypid);
 
 	/* Launch tracer. */
-	self->tracer = setup_trace_fixture(_metadata, tracer_syscall, NULL,
-					   false);
-}
-
-FIXTURE_TEARDOWN(TRACE_syscall)
-{
-	teardown_trace_fixture(_metadata, self->tracer);
-	if (self->prog.filter)
-		free(self->prog.filter);
-}
+	self->tracer = setup_trace_fixture(_metadata,
+					   variant->use_ptrace ? tracer_ptrace
+							       : tracer_seccomp,
+					   NULL, variant->use_ptrace);
 
-TEST_F(TRACE_syscall, ptrace_syscall_redirected)
-{
-	/* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */
-	teardown_trace_fixture(_metadata, self->tracer);
-	self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL,
-					   true);
-
-	/* Tracer will redirect getpid to getppid. */
-	EXPECT_NE(self->mypid, syscall(__NR_getpid));
-}
+	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+	ASSERT_EQ(0, ret);
 
-TEST_F(TRACE_syscall, ptrace_syscall_errno)
-{
-	/* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */
-	teardown_trace_fixture(_metadata, self->tracer);
-	self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL,
-					   true);
+	if (variant->use_ptrace)
+		return;
 
-	/* Tracer should skip the open syscall, resulting in ESRCH. */
-	EXPECT_SYSCALL_RETURN(-ESRCH, syscall(__NR_openat));
+	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
+	ASSERT_EQ(0, ret);
 }
 
-TEST_F(TRACE_syscall, ptrace_syscall_faked)
+FIXTURE_TEARDOWN(TRACE_syscall)
 {
-	/* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */
 	teardown_trace_fixture(_metadata, self->tracer);
-	self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL,
-					   true);
-
-	/* Tracer should skip the gettid syscall, resulting fake pid. */
-	EXPECT_SYSCALL_RETURN(45000, syscall(__NR_gettid));
 }
 
 TEST_F(TRACE_syscall, syscall_allowed)
 {
-	long ret;
-
-	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
-	ASSERT_EQ(0, ret);
-
 	/* getppid works as expected (no changes). */
 	EXPECT_EQ(self->parent, syscall(__NR_getppid));
 	EXPECT_NE(self->mypid, syscall(__NR_getppid));
@@ -1965,14 +1951,6 @@ TEST_F(TRACE_syscall, syscall_allowed)
 
 TEST_F(TRACE_syscall, syscall_redirected)
 {
-	long ret;
-
-	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
-	ASSERT_EQ(0, ret);
-
 	/* getpid has been redirected to getppid as expected. */
 	EXPECT_EQ(self->parent, syscall(__NR_getpid));
 	EXPECT_NE(self->mypid, syscall(__NR_getpid));
@@ -1980,33 +1958,17 @@ TEST_F(TRACE_syscall, syscall_redirected)
 
 TEST_F(TRACE_syscall, syscall_errno)
 {
-	long ret;
-
-	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* openat has been skipped and an errno return. */
+	/* Tracer should skip the open syscall, resulting in ESRCH. */
 	EXPECT_SYSCALL_RETURN(-ESRCH, syscall(__NR_openat));
 }
 
 TEST_F(TRACE_syscall, syscall_faked)
 {
-	long ret;
-
-	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* gettid has been skipped and an altered return value stored. */
+	/* Tracer skips the gettid syscall and store altered return value. */
 	EXPECT_SYSCALL_RETURN(45000, syscall(__NR_gettid));
 }
 
-TEST_F(TRACE_syscall, skip_after_RET_TRACE)
+TEST_F(TRACE_syscall, skip_after)
 {
 	struct sock_filter filter[] = {
 		BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
@@ -2021,14 +1983,7 @@ TEST_F(TRACE_syscall, skip_after_RET_TRACE)
 	};
 	long ret;
 
-	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* Install fixture filter. */
-	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* Install "errno on getppid" filter. */
+	/* Install additional "errno on getppid" filter. */
 	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
 	ASSERT_EQ(0, ret);
 
@@ -2038,7 +1993,7 @@ TEST_F(TRACE_syscall, skip_after_RET_TRACE)
 	EXPECT_EQ(EPERM, errno);
 }
 
-TEST_F_SIGNAL(TRACE_syscall, kill_after_RET_TRACE, SIGSYS)
+TEST_F_SIGNAL(TRACE_syscall, kill_after, SIGSYS)
 {
 	struct sock_filter filter[] = {
 		BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
@@ -2053,77 +2008,7 @@ TEST_F_SIGNAL(TRACE_syscall, kill_after_RET_TRACE, SIGSYS)
 	};
 	long ret;
 
-	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* Install fixture filter. */
-	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* Install "death on getppid" filter. */
-	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* Tracer will redirect getpid to getppid, and we should die. */
-	EXPECT_NE(self->mypid, syscall(__NR_getpid));
-}
-
-TEST_F(TRACE_syscall, skip_after_ptrace)
-{
-	struct sock_filter filter[] = {
-		BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
-			offsetof(struct seccomp_data, nr)),
-		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getppid, 0, 1),
-		BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ERRNO | EPERM),
-		BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
-	};
-	struct sock_fprog prog = {
-		.len = (unsigned short)ARRAY_SIZE(filter),
-		.filter = filter,
-	};
-	long ret;
-
-	/* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */
-	teardown_trace_fixture(_metadata, self->tracer);
-	self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL,
-					   true);
-
-	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* Install "errno on getppid" filter. */
-	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* Tracer will redirect getpid to getppid, and we should see EPERM. */
-	EXPECT_EQ(-1, syscall(__NR_getpid));
-	EXPECT_EQ(EPERM, errno);
-}
-
-TEST_F_SIGNAL(TRACE_syscall, kill_after_ptrace, SIGSYS)
-{
-	struct sock_filter filter[] = {
-		BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
-			offsetof(struct seccomp_data, nr)),
-		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getppid, 0, 1),
-		BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL),
-		BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
-	};
-	struct sock_fprog prog = {
-		.len = (unsigned short)ARRAY_SIZE(filter),
-		.filter = filter,
-	};
-	long ret;
-
-	/* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */
-	teardown_trace_fixture(_metadata, self->tracer);
-	self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL,
-					   true);
-
-	ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
-	ASSERT_EQ(0, ret);
-
-	/* Install "death on getppid" filter. */
+	/* Install additional "death on getppid" filter. */
 	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
 	ASSERT_EQ(0, ret);