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selftests/seccomp: Add test for unknown SECCOMP_RET kill behavior

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While we were testing for the behavior of unknown seccomp filter return
values, there was no test for how it acted in a thread group. Add a test
in the thread group tests for this.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2020-09-08 12:28:27 -07:00
parent 4d671d922d
commit 3932fcecd9
1 changed files with 37 additions and 6 deletions
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43
tools/testing/selftests/seccomp/seccomp_bpf.c
View file

@ -774,8 +774,15 @@ void *kill_thread(void *data)
return (void *)SIBLING_EXIT_UNKILLED; return (void *)SIBLING_EXIT_UNKILLED;
} }
enum kill_t {
KILL_THREAD,
KILL_PROCESS,
RET_UNKNOWN
};
/* Prepare a thread that will kill itself or both of us. */ /* Prepare a thread that will kill itself or both of us. */
void kill_thread_or_group(struct __test_metadata *_metadata, bool kill_process) void kill_thread_or_group(struct __test_metadata *_metadata,
enum kill_t kill_how)
{ {
pthread_t thread; pthread_t thread;
void *status; void *status;
@ -791,11 +798,12 @@ void kill_thread_or_group(struct __test_metadata *_metadata, bool kill_process)
.len = (unsigned short)ARRAY_SIZE(filter_thread), .len = (unsigned short)ARRAY_SIZE(filter_thread),
.filter = filter_thread, .filter = filter_thread,
}; };
int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAAA;
struct sock_filter filter_process[] = { struct sock_filter filter_process[] = {
BPF_STMT(BPF_LD|BPF_W|BPF_ABS, BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
offsetof(struct seccomp_data, nr)), offsetof(struct seccomp_data, nr)),
BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_prctl, 0, 1), BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_prctl, 0, 1),
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL_PROCESS), BPF_STMT(BPF_RET|BPF_K, kill),
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW), BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
}; };
struct sock_fprog prog_process = { struct sock_fprog prog_process = {
@ -808,13 +816,15 @@ void kill_thread_or_group(struct __test_metadata *_metadata, bool kill_process)
} }
ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0, ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0,
kill_process ? &prog_process : &prog_thread)); kill_how == KILL_THREAD ? &prog_thread
: &prog_process));
/* /*
* Add the KILL_THREAD rule again to make sure that the KILL_PROCESS * Add the KILL_THREAD rule again to make sure that the KILL_PROCESS
* flag cannot be downgraded by a new filter. * flag cannot be downgraded by a new filter.
*/ */
ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog_thread)); if (kill_how == KILL_PROCESS)
ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog_thread));
/* Start a thread that will exit immediately. */ /* Start a thread that will exit immediately. */
ASSERT_EQ(0, pthread_create(&thread, NULL, kill_thread, (void *)false)); ASSERT_EQ(0, pthread_create(&thread, NULL, kill_thread, (void *)false));
@ -842,7 +852,7 @@ TEST(KILL_thread)
child_pid = fork(); child_pid = fork();
ASSERT_LE(0, child_pid); ASSERT_LE(0, child_pid);
if (child_pid == 0) { if (child_pid == 0) {
kill_thread_or_group(_metadata, false); kill_thread_or_group(_metadata, KILL_THREAD);
_exit(38); _exit(38);
} }
@ -861,7 +871,7 @@ TEST(KILL_process)
child_pid = fork(); child_pid = fork();
ASSERT_LE(0, child_pid); ASSERT_LE(0, child_pid);
if (child_pid == 0) { if (child_pid == 0) {
kill_thread_or_group(_metadata, true); kill_thread_or_group(_metadata, KILL_PROCESS);
_exit(38); _exit(38);
} }
@ -872,6 +882,27 @@ TEST(KILL_process)
ASSERT_EQ(SIGSYS, WTERMSIG(status)); ASSERT_EQ(SIGSYS, WTERMSIG(status));
} }
TEST(KILL_unknown)
{
int status;
pid_t child_pid;
child_pid = fork();
ASSERT_LE(0, child_pid);
if (child_pid == 0) {
kill_thread_or_group(_metadata, RET_UNKNOWN);
_exit(38);
}
ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));
/* If the entire process was killed, we'll see SIGSYS. */
EXPECT_TRUE(WIFSIGNALED(status)) {
TH_LOG("Unknown SECCOMP_RET is only killing the thread?");
}
ASSERT_EQ(SIGSYS, WTERMSIG(status));
}
/* TODO(wad) add 64-bit versus 32-bit arg tests. */ /* TODO(wad) add 64-bit versus 32-bit arg tests. */
TEST(arg_out_of_range) TEST(arg_out_of_range)
{ {