diff options
| -rw-r--r-- | tools/testing/selftests/seccomp/seccomp_bpf.c | 176 |
1 files changed, 165 insertions, 11 deletions
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index 2e58549b2f02..03f1fa495d74 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -1021,8 +1021,8 @@ void tracer_stop(int sig) typedef void tracer_func_t(struct __test_metadata *_metadata, pid_t tracee, int status, void *args); -void tracer(struct __test_metadata *_metadata, int fd, pid_t tracee, - tracer_func_t tracer_func, void *args) +void start_tracer(struct __test_metadata *_metadata, int fd, pid_t tracee, + tracer_func_t tracer_func, void *args, bool ptrace_syscall) { int ret = -1; struct sigaction action = { @@ -1042,12 +1042,16 @@ void tracer(struct __test_metadata *_metadata, int fd, pid_t tracee, /* Wait for attach stop */ wait(NULL); - ret = ptrace(PTRACE_SETOPTIONS, tracee, NULL, PTRACE_O_TRACESECCOMP); + ret = ptrace(PTRACE_SETOPTIONS, tracee, NULL, ptrace_syscall ? + PTRACE_O_TRACESYSGOOD : + PTRACE_O_TRACESECCOMP); ASSERT_EQ(0, ret) { TH_LOG("Failed to set PTRACE_O_TRACESECCOMP"); kill(tracee, SIGKILL); } - ptrace(PTRACE_CONT, tracee, NULL, 0); + ret = ptrace(ptrace_syscall ? PTRACE_SYSCALL : PTRACE_CONT, + tracee, NULL, 0); + ASSERT_EQ(0, ret); /* Unblock the tracee */ ASSERT_EQ(1, write(fd, "A", 1)); @@ -1063,12 +1067,13 @@ void tracer(struct __test_metadata *_metadata, int fd, pid_t tracee, /* Child is dead. Time to go. */ return; - /* Make sure this is a seccomp event. */ - ASSERT_EQ(true, IS_SECCOMP_EVENT(status)); + /* Check if this is a seccomp event. */ + ASSERT_EQ(!ptrace_syscall, IS_SECCOMP_EVENT(status)); tracer_func(_metadata, tracee, status, args); - ret = ptrace(PTRACE_CONT, tracee, NULL, NULL); + ret = ptrace(ptrace_syscall ? PTRACE_SYSCALL : PTRACE_CONT, + tracee, NULL, 0); ASSERT_EQ(0, ret); } /* Directly report the status of our test harness results. */ @@ -1079,7 +1084,7 @@ void tracer(struct __test_metadata *_metadata, int fd, pid_t tracee, void cont_handler(int num) { } pid_t setup_trace_fixture(struct __test_metadata *_metadata, - tracer_func_t func, void *args) + tracer_func_t func, void *args, bool ptrace_syscall) { char sync; int pipefd[2]; @@ -1095,7 +1100,8 @@ pid_t setup_trace_fixture(struct __test_metadata *_metadata, signal(SIGALRM, cont_handler); if (tracer_pid == 0) { close(pipefd[0]); - tracer(_metadata, pipefd[1], tracee, func, args); + start_tracer(_metadata, pipefd[1], tracee, func, args, + ptrace_syscall); syscall(__NR_exit, 0); } close(pipefd[1]); @@ -1177,7 +1183,7 @@ FIXTURE_SETUP(TRACE_poke) /* Launch tracer. */ self->tracer = setup_trace_fixture(_metadata, tracer_poke, - &self->tracer_args); + &self->tracer_args, false); } FIXTURE_TEARDOWN(TRACE_poke) @@ -1399,6 +1405,29 @@ void tracer_syscall(struct __test_metadata *_metadata, pid_t tracee, } +void tracer_ptrace(struct __test_metadata *_metadata, pid_t tracee, + int status, void *args) +{ + int ret, nr; + unsigned long msg; + static bool entry; + + /* Make sure we got an empty message. */ + ret = ptrace(PTRACE_GETEVENTMSG, tracee, NULL, &msg); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, msg); + + /* The only way to tell PTRACE_SYSCALL entry/exit is by counting. */ + entry = !entry; + if (!entry) + return; + + nr = get_syscall(_metadata, tracee); + + if (nr == __NR_getpid) + change_syscall(_metadata, tracee, __NR_getppid); +} + FIXTURE_DATA(TRACE_syscall) { struct sock_fprog prog; pid_t tracer, mytid, mypid, parent; @@ -1440,7 +1469,8 @@ FIXTURE_SETUP(TRACE_syscall) ASSERT_NE(self->parent, self->mypid); /* Launch tracer. */ - self->tracer = setup_trace_fixture(_metadata, tracer_syscall, NULL); + self->tracer = setup_trace_fixture(_metadata, tracer_syscall, NULL, + false); } FIXTURE_TEARDOWN(TRACE_syscall) @@ -1500,6 +1530,130 @@ TEST_F(TRACE_syscall, syscall_dropped) EXPECT_NE(self->mytid, syscall(__NR_gettid)); } +TEST_F(TRACE_syscall, skip_after_RET_TRACE) +{ + 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; + + 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. */ + 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_RET_TRACE, 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; + + 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. */ + 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)); +} + #ifndef __NR_seccomp # if defined(__i386__) # define __NR_seccomp 354 |