As suggested by Andrew Morton in [1] add selftests for the new sys_pidfd_send_signal() syscall. This tests whether we can send a signal to an existing process and whether sending a signal to a process that has already exited fails with ESRCH. [1]: https://lore.kernel.org/lkml/20181228152012.dbf0508c2508138efc5f2bbe@xxxxxxxxxxxxxxxxxxxx/ Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Serge Hallyn <serge@xxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: Andy Lutomirsky <luto@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Aleksa Sarai <cyphar@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Florian Weimer <fweimer@xxxxxxxxxx> Signed-off-by: Christian Brauner <christian@xxxxxxxxxx> --- /* Changelog */ v6: - patch introduced v5..v0: - patch not present --- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/pidfd/Makefile | 6 + tools/testing/selftests/pidfd/pidfd_test.c | 130 +++++++++++++++++++++ 3 files changed, 137 insertions(+) create mode 100644 tools/testing/selftests/pidfd/Makefile create mode 100644 tools/testing/selftests/pidfd/pidfd_test.c diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 24b9934fb269..63b0d8a0ebf7 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -27,6 +27,7 @@ TARGETS += net TARGETS += netfilter TARGETS += networking/timestamping TARGETS += nsfs +TARGETS += pidfd TARGETS += powerpc TARGETS += proc TARGETS += pstore diff --git a/tools/testing/selftests/pidfd/Makefile b/tools/testing/selftests/pidfd/Makefile new file mode 100644 index 000000000000..deaf8073bc06 --- /dev/null +++ b/tools/testing/selftests/pidfd/Makefile @@ -0,0 +1,6 @@ +CFLAGS += -g -I../../../../usr/include/ + +TEST_GEN_PROGS := pidfd_test + +include ../lib.mk + diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c new file mode 100644 index 000000000000..edcd59979b10 --- /dev/null +++ b/tools/testing/selftests/pidfd/pidfd_test.c @@ -0,0 +1,130 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#define _GNU_SOURCE +#include <errno.h> +#include <fcntl.h> +#include <linux/types.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <syscall.h> +#include <sys/wait.h> +#include <unistd.h> + +#include "../kselftest.h" + +static inline int sys_pidfd_send_signal(int pidfd, int sig, siginfo_t *info, + unsigned int flags) +{ + return syscall(__NR_pidfd_send_signal, pidfd, sig, info, flags); +} + +static int signal_received; + +static void do_exit_success(int sig) +{ + signal_received = 1; +} + +/* + * Straightforward test to see whether pidfd_send_signal() works is to send + * a signal to ourselves. + */ +static int test_pidfd_send_signal_simple_success(void) +{ + int pidfd, ret; + const char *test_name = "pidfd_send_signal send SIGUSR1"; + + 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); + + signal(SIGUSR1, do_exit_success); + + 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", + test_name); + + if (signal_received != 1) + ksft_exit_fail_msg("%s test: Failed to receive signal\n", + test_name); + + signal_received = 0; + ksft_test_result_pass("%s test: Sent signal\n", test_name); + return 0; +} + +static void wait_for_pid(pid_t pid) +{ + int status, ret; + +again: + ret = waitpid(pid, &status, 0); + if (ret == -1) { + if (errno == EINTR) + goto again; + + return; + } + + if (ret != pid) + goto again; +} + +static int test_pidfd_send_signal_exited_fail(void) +{ + int pidfd, ret, saved_errno; + char buf[256]; + pid_t pid; + const char *test_name = "pidfd_send_signal signal exited process"; + + pid = fork(); + if (pid < 0) + ksft_exit_fail_msg("%s test: Failed to create new process\n", + test_name); + + if (pid == 0) + _exit(EXIT_SUCCESS); + + snprintf(buf, sizeof(buf), "/proc/%d", pid); + + pidfd = open(buf, O_DIRECTORY | O_CLOEXEC); + + wait_for_pid(pid); + + if (pidfd < 0) + ksft_exit_fail_msg( + "%s test: Failed to open process file descriptor\n", + test_name); + + ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0); + saved_errno = errno; + close(pidfd); + if (ret == 0) + ksft_exit_fail_msg( + "%s test: Managed to send signal to process even though it should have failed\n", + test_name); + + if (saved_errno != ESRCH) + ksft_exit_fail_msg( + "%s test: Expected to receive ESRCH as errno value but received %d instead\n", + test_name, saved_errno); + + ksft_test_result_pass("%s test: Failed to send signal as expected\n", + test_name); + return 0; +} + +int main(int argc, char **argv) +{ + ksft_print_header(); + + test_pidfd_send_signal_simple_success(); + test_pidfd_send_signal_exited_fail(); + + return ksft_exit_pass(); +} -- 2.19.1
