This verifies that SECCOMP_RET_KILL_PROCESS is higher priority than
SECCOMP_RET_KILL_THREAD. (This also moves a bunch of defines up earlier
in the file to use them earlier.)
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxx>
---
tools/testing/selftests/seccomp/seccomp_bpf.c | 228 +++++++++++++++++++-------
1 file changed, 168 insertions(+), 60 deletions(-)
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 5680e3ae33fd..fa097a270616 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -68,7 +68,17 @@
#define SECCOMP_MODE_FILTER 2
#endif
-#ifndef SECCOMP_RET_KILL_THREAD
+#ifndef SECCOMP_RET_ALLOW
+struct seccomp_data {
+ int nr;
+ __u32 arch;
+ __u64 instruction_pointer;
+ __u64 args[6];
+};
+#endif
+
+#ifndef SECCOMP_RET_KILL_PROCESS
+#define SECCOMP_RET_KILL_PROCESS 0x80000000U /* kill the process */
#define SECCOMP_RET_KILL_THREAD 0x00000000U /* kill the thread */
#endif
#ifndef SECCOMP_RET_KILL
@@ -82,17 +92,53 @@
#define SECCOMP_RET_LOG 0x7ffc0000U /* allow after logging */
#endif
-#ifndef SECCOMP_RET_ACTION
-/* Masks for the return value sections. */
-#define SECCOMP_RET_ACTION 0x7fff0000U
-#define SECCOMP_RET_DATA 0x0000ffffU
+#ifndef __NR_seccomp
+# if defined(__i386__)
+# define __NR_seccomp 354
+# elif defined(__x86_64__)
+# define __NR_seccomp 317
+# elif defined(__arm__)
+# define __NR_seccomp 383
+# elif defined(__aarch64__)
+# define __NR_seccomp 277
+# elif defined(__hppa__)
+# define __NR_seccomp 338
+# elif defined(__powerpc__)
+# define __NR_seccomp 358
+# elif defined(__s390__)
+# define __NR_seccomp 348
+# else
+# warning "seccomp syscall number unknown for this architecture"
+# define __NR_seccomp 0xffff
+# endif
+#endif
-struct seccomp_data {
- int nr;
- __u32 arch;
- __u64 instruction_pointer;
- __u64 args[6];
-};
+#ifndef SECCOMP_SET_MODE_STRICT
+#define SECCOMP_SET_MODE_STRICT 0
+#endif
+
+#ifndef SECCOMP_SET_MODE_FILTER
+#define SECCOMP_SET_MODE_FILTER 1
+#endif
+
+#ifndef SECCOMP_GET_ACTION_AVAIL
+#define SECCOMP_GET_ACTION_AVAIL 2
+#endif
+
+#ifndef SECCOMP_FILTER_FLAG_TSYNC
+#define SECCOMP_FILTER_FLAG_TSYNC 1
+#endif
+
+#ifndef SECCOMP_FILTER_FLAG_LOG
+#define SECCOMP_FILTER_FLAG_LOG 2
+#endif
+
+#ifndef seccomp
+int seccomp(unsigned int op, unsigned int flags, void *args)
+{
+ errno = 0;
+ return syscall(__NR_seccomp, op, flags, args);
+}
#endif
#if __BYTE_ORDER == __LITTLE_ENDIAN
@@ -550,6 +596,117 @@ TEST_SIGNAL(KILL_one_arg_six, SIGSYS)
close(fd);
}
+/* This is a thread task to die via seccomp filter violation. */
+void *kill_thread(void *data)
+{
+ bool die = (bool)data;
+
+ if (die) {
+ prctl(PR_GET_SECCOMP, 0, 0, 0, 0);
+ return (void *)SIBLING_EXIT_FAILURE;
+ }
+
+ return (void *)SIBLING_EXIT_UNKILLED;
+}
+
+/* Prepare a thread that will kill itself or both of us. */
+void kill_thread_or_group(struct __test_metadata *_metadata, bool kill_process)
+{
+ pthread_t thread;
+ void *status;
+ /* Kill only when calling __NR_prctl. */
+ struct sock_filter filter_thread[] = {
+ BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
+ offsetof(struct seccomp_data, nr)),
+ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_prctl, 0, 1),
+ BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL_THREAD),
+ BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
+ };
+ struct sock_fprog prog_thread = {
+ .len = (unsigned short)ARRAY_SIZE(filter_thread),
+ .filter = filter_thread,
+ };
+ struct sock_filter filter_process[] = {
+ BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
+ offsetof(struct seccomp_data, nr)),
+ 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, SECCOMP_RET_ALLOW),
+ };
+ struct sock_fprog prog_process = {
+ .len = (unsigned short)ARRAY_SIZE(filter_process),
+ .filter = filter_process,
+ };
+
+ ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
+ TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS!");
+ }
+
+ ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0,
+ kill_process ? &prog_process : &prog_thread));
+
+ /*
+ * Add the KILL_THREAD rule again to make sure that the KILL_PROCESS
+ * flag cannot be downgraded by a new filter.
+ */
+ ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog_thread));
+
+ /* Start a thread that will exit immediately. */
+ ASSERT_EQ(0, pthread_create(&thread, NULL, kill_thread, (void *)false));
+ ASSERT_EQ(0, pthread_join(thread, &status));
+ ASSERT_EQ(SIBLING_EXIT_UNKILLED, (unsigned long)status);
+
+ /* Start a thread that will die immediately. */
+ ASSERT_EQ(0, pthread_create(&thread, NULL, kill_thread, (void *)true));
+ ASSERT_EQ(0, pthread_join(thread, &status));
+ ASSERT_NE(SIBLING_EXIT_FAILURE, (unsigned long)status);
+
+ /*
+ * If we get here, only the spawned thread died. Let the parent know
+ * the whole process didn't die (i.e. this thread, the spawner,
+ * stayed running).
+ */
+ exit(42);
+}
+
+TEST(KILL_thread)
+{
+ int status;
+ pid_t child_pid;
+
+ child_pid = fork();
+ ASSERT_LE(0, child_pid);
+ if (child_pid == 0) {
+ kill_thread_or_group(_metadata, false);
+ _exit(38);
+ }
+
+ ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));
+
+ /* If only the thread was killed, we'll see exit 42. */
+ ASSERT_TRUE(WIFEXITED(status));
+ ASSERT_EQ(42, WEXITSTATUS(status));
+}
+
+TEST(KILL_process)
+{
+ int status;
+ pid_t child_pid;
+
+ child_pid = fork();
+ ASSERT_LE(0, child_pid);
+ if (child_pid == 0) {
+ kill_thread_or_group(_metadata, true);
+ _exit(38);
+ }
+
+ ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));
+
+ /* If the entire process was killed, we'll see SIGSYS. */
+ ASSERT_TRUE(WIFSIGNALED(status));
+ ASSERT_EQ(SIGSYS, WTERMSIG(status));
+}
+
/* TODO(wad) add 64-bit versus 32-bit arg tests. */
TEST(arg_out_of_range)
{
@@ -1773,55 +1930,6 @@ TEST_F_SIGNAL(TRACE_syscall, kill_after_ptrace, SIGSYS)
EXPECT_NE(self->mypid, syscall(__NR_getpid));
}
-#ifndef __NR_seccomp
-# if defined(__i386__)
-# define __NR_seccomp 354
-# elif defined(__x86_64__)
-# define __NR_seccomp 317
-# elif defined(__arm__)
-# define __NR_seccomp 383
-# elif defined(__aarch64__)
-# define __NR_seccomp 277
-# elif defined(__hppa__)
-# define __NR_seccomp 338
-# elif defined(__powerpc__)
-# define __NR_seccomp 358
-# elif defined(__s390__)
-# define __NR_seccomp 348
-# else
-# warning "seccomp syscall number unknown for this architecture"
-# define __NR_seccomp 0xffff
-# endif
-#endif
-
-#ifndef SECCOMP_SET_MODE_STRICT
-#define SECCOMP_SET_MODE_STRICT 0
-#endif
-
-#ifndef SECCOMP_SET_MODE_FILTER
-#define SECCOMP_SET_MODE_FILTER 1
-#endif
-
-#ifndef SECCOMP_GET_ACTION_AVAIL
-#define SECCOMP_GET_ACTION_AVAIL 2
-#endif
-
-#ifndef SECCOMP_FILTER_FLAG_TSYNC
-#define SECCOMP_FILTER_FLAG_TSYNC 1
-#endif
-
-#ifndef SECCOMP_FILTER_FLAG_LOG
-#define SECCOMP_FILTER_FLAG_LOG 2
-#endif
-
-#ifndef seccomp
-int seccomp(unsigned int op, unsigned int flags, void *args)
-{
- errno = 0;
- return syscall(__NR_seccomp, op, flags, args);
-}
-#endif
-
TEST(seccomp_syscall)
{
struct sock_filter filter[] = {
--
2.7.4
--
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