Add tests to assert that PIDFD_SELF_* correctly refers to the current thread and process.
This is only practically meaningful to pidfd_send_signal() and pidfd_getfd(), but also explicitly test that we disallow this feature for setns() where it would make no sense. We cannot reasonably wait on ourself using waitid(P_PIDFD, ...) so while in theory PIDFD_SELF_* would work here, we'd be left blocked if we tried it. We defer testing of mm-specific functionality which uses pidfd, namely process_madvise() and process_mrelease() to mm testing (though note the latter can not be sensibly tested as it would require the testing process to be dying). Signed-off-by: Lorenzo Stoakes <lorenzo.stoa...@oracle.com> --- tools/testing/selftests/pidfd/pidfd.h | 8 + .../selftests/pidfd/pidfd_getfd_test.c | 141 ++++++++++++++++++ .../selftests/pidfd/pidfd_setns_test.c | 11 ++ tools/testing/selftests/pidfd/pidfd_test.c | 76 ++++++++-- 4 files changed, 224 insertions(+), 12 deletions(-) diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h index 88d6830ee004..1640b711889b 100644 --- a/tools/testing/selftests/pidfd/pidfd.h +++ b/tools/testing/selftests/pidfd/pidfd.h @@ -50,6 +50,14 @@ #define PIDFD_NONBLOCK O_NONBLOCK #endif +/* System header file may not have this available. */ +#ifndef PIDFD_SELF_THREAD +#define PIDFD_SELF_THREAD -100 +#endif +#ifndef PIDFD_SELF_THREAD_GROUP +#define PIDFD_SELF_THREAD_GROUP -200 +#endif + /* * The kernel reserves 300 pids via RESERVED_PIDS in kernel/pid.c * That means, when it wraps around any pid < 300 will be skipped. diff --git a/tools/testing/selftests/pidfd/pidfd_getfd_test.c b/tools/testing/selftests/pidfd/pidfd_getfd_test.c index cd51d547b751..48d224b13c01 100644 --- a/tools/testing/selftests/pidfd/pidfd_getfd_test.c +++ b/tools/testing/selftests/pidfd/pidfd_getfd_test.c @@ -6,6 +6,7 @@ #include <limits.h> #include <linux/types.h> #include <poll.h> +#include <pthread.h> #include <sched.h> #include <signal.h> #include <stdio.h> @@ -15,6 +16,7 @@ #include <sys/prctl.h> #include <sys/wait.h> #include <unistd.h> +#include <sys/mman.h> #include <sys/socket.h> #include <linux/kcmp.h> @@ -114,6 +116,94 @@ static int child(int sk) return ret; } +static int __pidfd_self_thread_worker(unsigned long page_size) +{ + int memfd; + int newfd; + char *ptr; + int err = 0; + + /* + * Unshare our FDs so we have our own set. This means + * PIDFD_SELF_THREAD_GROUP will fal. + */ + if (unshare(CLONE_FILES) < 0) { + err = -errno; + goto exit; + } + + /* Truncate, map in and write to our memfd. */ + memfd = sys_memfd_create("test_self_child", 0); + if (memfd < 0) { + err = -errno; + goto exit; + } + + if (ftruncate(memfd, page_size)) { + err = -errno; + goto exit_close_memfd; + } + + ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, + MAP_SHARED, memfd, 0); + if (ptr == MAP_FAILED) { + err = -errno; + goto exit_close_memfd; + } + ptr[0] = 'y'; + if (munmap(ptr, page_size)) { + err = -errno; + goto exit_close_memfd; + } + + /* Get a thread-local duplicate of our memfd. */ + newfd = sys_pidfd_getfd(PIDFD_SELF_THREAD, memfd, 0); + if (newfd < 0) { + err = -errno; + goto exit_close_memfd; + } + + if (memfd == newfd) { + err = -EINVAL; + goto exit_close_fds; + } + + /* Map in new fd and make sure that the data is as expected. */ + ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, + MAP_SHARED, newfd, 0); + if (ptr == MAP_FAILED) { + err = -errno; + goto exit_close_fds; + } + + if (ptr[0] != 'y') { + err = -EINVAL; + goto exit_close_fds; + } + + if (munmap(ptr, page_size)) { + err = -errno; + goto exit_close_fds; + } + +exit_close_fds: + close(newfd); +exit_close_memfd: + close(memfd); +exit: + return err; +} + +static void *pidfd_self_thread_worker(void *arg) +{ + unsigned long page_size = (unsigned long)arg; + int ret; + + /* We forward any errors for the caller to handle. */ + ret = __pidfd_self_thread_worker(page_size); + return (void *)(intptr_t)ret; +} + FIXTURE(child) { /* @@ -264,6 +354,57 @@ TEST_F(child, no_strange_EBADF) EXPECT_EQ(errno, ESRCH); } +TEST(pidfd_self) +{ + int memfd = sys_memfd_create("test_self", 0); + unsigned long page_size = sysconf(_SC_PAGESIZE); + int newfd; + char *ptr; + pthread_t thread; + void *res; + int err; + + ASSERT_GE(memfd, 0); + ASSERT_EQ(ftruncate(memfd, page_size), 0); + + /* + * Map so we can assert that the duplicated fd references the same + * memory. + */ + ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, + MAP_SHARED, memfd, 0); + ASSERT_NE(ptr, MAP_FAILED); + ptr[0] = 'x'; + ASSERT_EQ(munmap(ptr, page_size), 0); + + /* Now get a duplicate of our memfd. */ + newfd = sys_pidfd_getfd(PIDFD_SELF_THREAD_GROUP, memfd, 0); + ASSERT_GE(newfd, 0); + ASSERT_NE(memfd, newfd); + + /* Now map duplicate fd and make sure it references the same memory. */ + ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, + MAP_SHARED, newfd, 0); + ASSERT_NE(ptr, MAP_FAILED); + ASSERT_EQ(ptr[0], 'x'); + ASSERT_EQ(munmap(ptr, page_size), 0); + + /* Cleanup. */ + close(memfd); + close(newfd); + + /* + * Fire up the thread and assert that we can lookup the thread-specific + * PIDFD_SELF_THREAD (also aliased by PIDFD_SELF). + */ + ASSERT_EQ(pthread_create(&thread, NULL, pidfd_self_thread_worker, + (void *)page_size), 0); + ASSERT_EQ(pthread_join(thread, &res), 0); + err = (int)(intptr_t)res; + + ASSERT_EQ(err, 0); +} + #if __NR_pidfd_getfd == -1 int main(void) { diff --git a/tools/testing/selftests/pidfd/pidfd_setns_test.c b/tools/testing/selftests/pidfd/pidfd_setns_test.c index 7c2a4349170a..bbd39dc5ceb7 100644 --- a/tools/testing/selftests/pidfd/pidfd_setns_test.c +++ b/tools/testing/selftests/pidfd/pidfd_setns_test.c @@ -752,4 +752,15 @@ TEST(setns_einval) close(fd); } +TEST(setns_pidfd_self_disallowed) +{ + ASSERT_EQ(setns(PIDFD_SELF_THREAD, 0), -1); + EXPECT_EQ(errno, EBADF); + + errno = 0; + + ASSERT_EQ(setns(PIDFD_SELF_THREAD_GROUP, 0), -1); + EXPECT_EQ(errno, EBADF); +} + TEST_HARNESS_MAIN diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c index 9faa686f90e4..440447cf89ba 100644 --- a/tools/testing/selftests/pidfd/pidfd_test.c +++ b/tools/testing/selftests/pidfd/pidfd_test.c @@ -42,12 +42,41 @@ static pid_t pidfd_clone(int flags, int *pidfd, int (*fn)(void *)) #endif } -static int signal_received; +static pthread_t signal_received; static void set_signal_received_on_sigusr1(int sig) { if (sig == SIGUSR1) - signal_received = 1; + signal_received = pthread_self(); +} + +static int send_signal(int pidfd) +{ + int ret = 0; + + if (sys_pidfd_send_signal(pidfd, SIGUSR1, NULL, 0) < 0) { + ret = -EINVAL; + goto exit; + } + + if (signal_received != pthread_self()) { + ret = -EINVAL; + goto exit; + } + +exit: + signal_received = 0; + return ret; +} + +static void *send_signal_worker(void *arg) +{ + int pidfd = (int)(intptr_t)arg; + int ret; + + /* We forward any errors for the caller to handle. */ + ret = send_signal(pidfd); + return (void *)(intptr_t)ret; } /* @@ -56,8 +85,11 @@ static void set_signal_received_on_sigusr1(int sig) */ static int test_pidfd_send_signal_simple_success(void) { - int pidfd, ret; + int pidfd; const char *test_name = "pidfd_send_signal send SIGUSR1"; + pthread_t thread; + void *thread_res; + int err; if (!have_pidfd_send_signal) { ksft_test_result_skip( @@ -66,25 +98,45 @@ static int test_pidfd_send_signal_simple_success(void) return 0; } + signal(SIGUSR1, set_signal_received_on_sigusr1); + + /* Try sending a signal to ourselves via /proc/self. */ pidfd = open("/proc/self", O_DIRECTORY | O_CLOEXEC); if (pidfd < 0) ksft_exit_fail_msg( "%s test: Failed to open process file descriptor\n", test_name); + err = send_signal(pidfd); + if (err) + ksft_exit_fail_msg( + "%s test: Error %d on sending pidfd signal\n", + test_name, err); + close(pidfd); - signal(SIGUSR1, set_signal_received_on_sigusr1); + /* Now try the same thing only using PIDFD_SELF_THREAD_GROUP. */ + err = send_signal(PIDFD_SELF_THREAD_GROUP); + if (err) + ksft_exit_fail_msg( + "%s test: Error %d on PIDFD_SELF_THREAD_GROUP signal\n", + test_name, err); - ret = sys_pidfd_send_signal(pidfd, SIGUSR1, NULL, 0); - close(pidfd); - if (ret < 0) - ksft_exit_fail_msg("%s test: Failed to send signal\n", + /* + * Now try the same thing in a thread and assert thread ID is equal to + * worker thread ID. + */ + if (pthread_create(&thread, NULL, send_signal_worker, + (void *)(intptr_t)PIDFD_SELF_THREAD)) + ksft_exit_fail_msg("%s test: Failed to create thread\n", test_name); - - if (signal_received != 1) - ksft_exit_fail_msg("%s test: Failed to receive signal\n", + if (pthread_join(thread, &thread_res)) + ksft_exit_fail_msg("%s test: Failed to join thread\n", test_name); + err = (int)(intptr_t)thread_res; + if (err) + ksft_exit_fail_msg( + "%s test: Error %d on PIDFD_SELF_THREAD signal\n", + test_name, err); - signal_received = 0; ksft_test_result_pass("%s test: Sent signal\n", test_name); return 0; } -- 2.46.2