@@ -9,3 +9,4 @@ pidfd_setns_test
pidfd_file_handle_test
pidfd_bind_mount
pidfd_info_test
+pidfd_exec_helper
@@ -5,5 +5,7 @@ TEST_GEN_PROGS := pidfd_test pidfd_fdinfo_test pidfd_open_test \
pidfd_poll_test pidfd_wait pidfd_getfd_test pidfd_setns_test \
pidfd_file_handle_test pidfd_bind_mount pidfd_info_test
+TEST_GEN_PROGS_EXTENDED := pidfd_exec_helper
+
include ../lib.mk
@@ -254,4 +254,11 @@ static inline ssize_t write_nointr(int fd, const void *buf, size_t count)
return ret;
}
+static inline int sys_execveat(int dirfd, const char *pathname,
+ char *const argv[], char *const envp[],
+ int flags)
+{
+ return syscall(__NR_execveat, dirfd, pathname, argv, envp, flags);
+}
+
#endif /* __PIDFD_H */
new file mode 100644
@@ -0,0 +1,12 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[])
+{
+ if (pause())
+ _exit(EXIT_FAILURE);
+
+ _exit(EXIT_SUCCESS);
+}
@@ -369,4 +369,106 @@ TEST_F(pidfd_info, thread_group)
EXPECT_EQ(close(pidfd_thread), 0);
}
+static void *pidfd_info_thread_exec(void *arg)
+{
+ pid_t pid_thread = gettid();
+ int ipc_socket = *(int *)arg;
+
+ /* Inform the grand-parent what the tid of this thread is. */
+ if (write_nointr(ipc_socket, &pid_thread, sizeof(pid_thread)) != sizeof(pid_thread))
+ return NULL;
+
+ if (read_nointr(ipc_socket, &pid_thread, sizeof(pid_thread)) != sizeof(pid_thread))
+ return NULL;
+
+ close(ipc_socket);
+
+ sys_execveat(AT_FDCWD, "pidfd_exec_helper", NULL, NULL, 0);
+ return NULL;
+}
+
+TEST_F(pidfd_info, thread_group_exec)
+{
+ pid_t pid_leader, pid_thread;
+ pthread_t thread;
+ int nevents, pidfd_leader, pidfd_thread, ret;
+ int ipc_sockets[2];
+ struct pollfd fds = {};
+ struct pidfd_info info = {
+ .mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT,
+ };
+
+ ret = socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets);
+ EXPECT_EQ(ret, 0);
+
+ pid_leader = create_child(&pidfd_leader, 0);
+ EXPECT_GE(pid_leader, 0);
+
+ if (pid_leader == 0) {
+ close(ipc_sockets[0]);
+
+ /* The thread will outlive the thread-group leader. */
+ if (pthread_create(&thread, NULL, pidfd_info_thread_exec, &ipc_sockets[1]))
+ syscall(__NR_exit, EXIT_FAILURE);
+
+ /* Make the thread-group leader exit prematurely. */
+ syscall(__NR_exit, EXIT_SUCCESS);
+ }
+
+ /* Retrieve the tid of the thread. */
+ EXPECT_EQ(close(ipc_sockets[1]), 0);
+ ASSERT_EQ(read_nointr(ipc_sockets[0], &pid_thread, sizeof(pid_thread)), sizeof(pid_thread));
+
+ /* Opening a thread as a PIDFD_THREAD must succeed. */
+ pidfd_thread = sys_pidfd_open(pid_thread, PIDFD_THREAD);
+ ASSERT_GE(pidfd_thread, 0);
+
+ /* Now that we've opened a thread-specific pidfd the thread can exec. */
+ ASSERT_EQ(write_nointr(ipc_sockets[0], &pid_thread, sizeof(pid_thread)), sizeof(pid_thread));
+ EXPECT_EQ(close(ipc_sockets[0]), 0);
+
+ /* Wait until the kernel has SIGKILLed the thread. */
+ fds.events = POLLHUP;
+ fds.fd = pidfd_thread;
+ nevents = poll(&fds, 1, -1);
+ ASSERT_EQ(nevents, 1);
+ /* The thread has been reaped. */
+ ASSERT_TRUE(!!(fds.revents & POLLHUP));
+
+ /* Retrieve thread-specific exit info from pidfd. */
+ ASSERT_EQ(ioctl(pidfd_thread, PIDFD_GET_INFO, &info), 0);
+ ASSERT_FALSE(!!(info.mask & PIDFD_INFO_CREDS));
+ ASSERT_TRUE(!!(info.mask & PIDFD_INFO_EXIT));
+ /*
+ * While the kernel will have SIGKILLed the whole thread-group
+ * during exec it will cause the individual threads to exit
+ * cleanly.
+ */
+ ASSERT_TRUE(WIFEXITED(info.exit_code));
+ ASSERT_EQ(WEXITSTATUS(info.exit_code), 0);
+
+ /*
+ * The thread-group leader is still alive, the thread has taken
+ * over its struct pid and thus its pid number.
+ */
+ info.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT;
+ ASSERT_EQ(ioctl(pidfd_leader, PIDFD_GET_INFO, &info), 0);
+ ASSERT_TRUE(!!(info.mask & PIDFD_INFO_CREDS));
+ ASSERT_FALSE(!!(info.mask & PIDFD_INFO_EXIT));
+ ASSERT_EQ(info.pid, pid_leader);
+
+ /* Take down the thread-group leader. */
+ EXPECT_EQ(sys_pidfd_send_signal(pidfd_leader, SIGKILL, NULL, 0), 0);
+ EXPECT_EQ(sys_waitid(P_PIDFD, pidfd_leader, NULL, WEXITED), 0);
+
+ /* Retrieve exit information for the thread-group leader. */
+ info.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT;
+ ASSERT_EQ(ioctl(pidfd_leader, PIDFD_GET_INFO, &info), 0);
+ ASSERT_FALSE(!!(info.mask & PIDFD_INFO_CREDS));
+ ASSERT_TRUE(!!(info.mask & PIDFD_INFO_EXIT));
+
+ EXPECT_EQ(close(pidfd_leader), 0);
+ EXPECT_EQ(close(pidfd_thread), 0);
+}
+
TEST_HARNESS_MAIN
Add a selftest for PIDFD_INFO_EXIT behavior. Signed-off-by: Christian Brauner <brauner@kernel.org> --- tools/testing/selftests/pidfd/.gitignore | 1 + tools/testing/selftests/pidfd/Makefile | 2 + tools/testing/selftests/pidfd/pidfd.h | 7 ++ .../selftests/pidfd/pidfd_exec_helper.c | 12 +++ .../testing/selftests/pidfd/pidfd_info_test.c | 102 ++++++++++++++++++ 5 files changed, 124 insertions(+) create mode 100644 tools/testing/selftests/pidfd/pidfd_exec_helper.c