[PATCH v4 4/4] seccomp: Add tests for SECCOMP_RET_LOG

From: Tyler Hicks
Date: Mon Feb 13 2017 - 22:56:36 EST

Extend the kernel selftests for seccomp to test the newly added
SECCOMP_RET_LOG action. The added tests follow the example of existing
tests.

Unfortunately, the tests are not capable of inspecting the audit log to
verify that the syscall was logged.

Signed-off-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxx>
---
tools/testing/selftests/seccomp/seccomp_bpf.c | 94 +++++++++++++++++++++++++++
1 file changed, 94 insertions(+)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 03f1fa4..5633b42 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -87,6 +87,10 @@ struct seccomp_data {
};
#endif

+#ifndef SECCOMP_RET_LOG
+#define SECCOMP_RET_LOG 0x7ffc0000U /* allow after logging */
+#endif
+
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define syscall_arg(_n) (offsetof(struct seccomp_data, args[_n]))
#elif __BYTE_ORDER == __BIG_ENDIAN
@@ -342,6 +346,28 @@ TEST(empty_prog)
EXPECT_EQ(EINVAL, errno);
}

+TEST(log_all)
+{
+ struct sock_filter filter[] = {
+ BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_LOG),
+ };
+ struct sock_fprog prog = {
+ .len = (unsigned short)ARRAY_SIZE(filter),
+ .filter = filter,
+ };
+ long ret;
+ pid_t parent = getppid();
+
+ ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+ ASSERT_EQ(0, ret);
+
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog);
+ ASSERT_EQ(0, ret);
+
+ /* getppid() should succeed and be logged (no check for logging) */
+ EXPECT_EQ(parent, syscall(__NR_getppid));
+}
+
TEST_SIGNAL(unknown_ret_is_kill_inside, SIGSYS)
{
struct sock_filter filter[] = {
@@ -735,6 +761,7 @@ TEST_F(TRAP, handler)

FIXTURE_DATA(precedence) {
struct sock_fprog allow;
+ struct sock_fprog log;
struct sock_fprog trace;
struct sock_fprog error;
struct sock_fprog trap;
@@ -746,6 +773,13 @@ FIXTURE_SETUP(precedence)
struct sock_filter allow_insns[] = {
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
};
+ struct sock_filter log_insns[] = {
+ BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
+ offsetof(struct seccomp_data, nr)),
+ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getpid, 1, 0),
+ BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
+ BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_LOG),
+ };
struct sock_filter trace_insns[] = {
BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
offsetof(struct seccomp_data, nr)),
@@ -782,6 +816,7 @@ FIXTURE_SETUP(precedence)
memcpy(self->_x.filter, &_x##_insns, sizeof(_x##_insns)); \
self->_x.len = (unsigned short)ARRAY_SIZE(_x##_insns)
FILTER_ALLOC(allow);
+ FILTER_ALLOC(log);
FILTER_ALLOC(trace);
FILTER_ALLOC(error);
FILTER_ALLOC(trap);
@@ -792,6 +827,7 @@ FIXTURE_TEARDOWN(precedence)
{
#define FILTER_FREE(_x) if (self->_x.filter) free(self->_x.filter)
FILTER_FREE(allow);
+ FILTER_FREE(log);
FILTER_FREE(trace);
FILTER_FREE(error);
FILTER_FREE(trap);
@@ -809,6 +845,8 @@ TEST_F(precedence, allow_ok)

ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
@@ -833,6 +871,8 @@ TEST_F_SIGNAL(precedence, kill_is_highest, SIGSYS)

ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
@@ -864,6 +904,8 @@ TEST_F_SIGNAL(precedence, kill_is_highest_in_any_order, SIGSYS)
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trap);
@@ -885,6 +927,8 @@ TEST_F_SIGNAL(precedence, trap_is_second, SIGSYS)

ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
@@ -910,6 +954,8 @@ TEST_F_SIGNAL(precedence, trap_is_second_in_any_order, SIGSYS)
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trap);
ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
@@ -931,6 +977,8 @@ TEST_F(precedence, errno_is_third)

ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
@@ -949,6 +997,8 @@ TEST_F(precedence, errno_is_third_in_any_order)
ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
ASSERT_EQ(0, ret);

+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->error);
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
@@ -971,6 +1021,8 @@ TEST_F(precedence, trace_is_fourth)

ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->trace);
ASSERT_EQ(0, ret);
/* Should work just fine. */
@@ -992,12 +1044,54 @@ TEST_F(precedence, trace_is_fourth_in_any_order)
ASSERT_EQ(0, ret);
ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
/* Should work just fine. */
EXPECT_EQ(parent, syscall(__NR_getppid));
/* No ptracer */
EXPECT_EQ(-1, syscall(__NR_getpid));
}

+TEST_F(precedence, log_is_fifth)
+{
+ pid_t mypid, parent;
+ long ret;
+
+ mypid = getpid();
+ parent = getppid();
+ ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+ ASSERT_EQ(0, ret);
+
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
+ ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
+ /* Should work just fine. */
+ EXPECT_EQ(parent, syscall(__NR_getppid));
+ /* Should also work just fine */
+ EXPECT_EQ(mypid, syscall(__NR_getpid));
+}
+
+TEST_F(precedence, log_is_fifth_in_any_order)
+{
+ pid_t mypid, parent;
+ long ret;
+
+ mypid = getpid();
+ parent = getppid();
+ ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+ ASSERT_EQ(0, ret);
+
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->log);
+ ASSERT_EQ(0, ret);
+ ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->allow);
+ ASSERT_EQ(0, ret);
+ /* Should work just fine. */
+ EXPECT_EQ(parent, syscall(__NR_getppid));
+ /* Should also work just fine */
+ EXPECT_EQ(mypid, syscall(__NR_getpid));
+}
+
#ifndef PTRACE_O_TRACESECCOMP
#define PTRACE_O_TRACESECCOMP 0x00000080
#endif
--
2.7.4