[v7,2/2] selftests: add tests for pidfd_send_signal()

Message ID	20190102161654.9093-2-christian@brauner.io (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-fsdevel-owner@kernel.org> From: Christian Brauner <christian@brauner.io> To: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, luto@kernel.org, arnd@arndb.de, serge@hallyn.com, keescook@chromium.org, akpm@linux-foundation.org Cc: jannh@google.com, oleg@redhat.com, cyphar@cyphar.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, dancol@google.com, timmurray@google.com, fweimer@redhat.com, tglx@linutronix.de, x86@kernel.org, ebiederm@xmission.com, Christian Brauner <christian@brauner.io> Subject: [PATCH v7 2/2] selftests: add tests for pidfd_send_signal() Date: Wed, 2 Jan 2019 17:16:54 +0100 Message-Id: <20190102161654.9093-2-christian@brauner.io> In-Reply-To: <20190102161654.9093-1-christian@brauner.io> References: <20190102161654.9093-1-christian@brauner.io> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk
Series	[v7,1/2] signal: add pidfd_send_signal() syscall \| expand [v7,1/2] signal: add pidfd_send_signal() syscall [v7,2/2] selftests: add tests for pidfd_send_signal()

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index eb54df682d56..84dd78a684e4 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -29,6 +29,7 @@ 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..d59378a93782 --- /dev/null +++ b/tools/testing/selftests/pidfd/pidfd_test.c @@ -0,0 +1,381 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#define _GNU_SOURCE +#include <errno.h> +#include <fcntl.h> +#include <linux/types.h> +#include <sched.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <syscall.h> +#include <sys/mount.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 set_signal_received_on_sigusr1(int sig) +{ + if (sig == SIGUSR1) + signal_received = 1; +} + +/* + * Straightforward test to see whether pidfd_send_signal() works is to send + * a signal to ourself. + */ +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, set_signal_received_on_sigusr1); + + 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 int wait_for_pid(pid_t pid) +{ + int status, ret; + +again: + ret = waitpid(pid, &status, 0); + if (ret == -1) { + if (errno == EINTR) + goto again; + + return -1; + } + + if (ret != pid) + goto again; + + if (!WIFEXITED(status)) + return -1; + + return WEXITSTATUS(status); +} + +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); + + (void)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; +} + +/* + * The kernel reserves 300 pids via RESERVED_PIDS in kernel/pid.c + * That means, when it wraps around any pid < 300 will be skipped. + * So we need to use a pid > 300 in order to test recycling. + */ +#define PID_RECYCLE 1000 + +/* + * Maximum number of cycles we allow. This is equivalent to PID_MAX_DEFAULT. + * If users set a higher limit or we have cycled PIDFD_MAX_DEFAULT number of + * times then we skip the test to not go into an infinite loop or block for a + * long time. + */ +#define PIDFD_MAX_DEFAULT 0x8000 + +/* + * Define a few custom error codes for the child process to clearly indicate + * what is happening. This way we can tell the difference between a system + * error, a test error, etc. + */ +#define PIDFD_PASS 0 +#define PIDFD_FAIL 1 +#define PIDFD_ERROR 2 +#define PIDFD_SKIP 3 +#define PIDFD_XFAIL 4 + +static int test_pidfd_send_signal_recycled_pid_fail(void) +{ + int i, ret; + pid_t pid1; + const char *test_name = "pidfd_send_signal signal recycled pid"; + + ret = unshare(CLONE_NEWPID); + if (ret < 0) + ksft_exit_fail_msg("%s test: Failed to unshare pid namespace\n", + test_name); + + ret = unshare(CLONE_NEWNS); + if (ret < 0) + ksft_exit_fail_msg( + "%s test: Failed to unshare mount namespace\n", + test_name); + + ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0); + if (ret < 0) + ksft_exit_fail_msg("%s test: Failed to remount / private\n", + test_name); + + /* pid 1 in new pid namespace */ + pid1 = fork(); + if (pid1 < 0) + ksft_exit_fail_msg("%s test: Failed to create new process\n", + test_name); + + if (pid1 == 0) { + char buf[256]; + pid_t pid2; + int pidfd = -1; + + (void)umount2("/proc", MNT_DETACH); + ret = mount("proc", "/proc", "proc", 0, NULL); + if (ret < 0) + _exit(PIDFD_ERROR); + + /* grab pid PID_RECYCLE */ + for (i = 0; i <= PIDFD_MAX_DEFAULT; i++) { + pid2 = fork(); + if (pid2 < 0) + _exit(PIDFD_ERROR); + + if (pid2 == 0) + _exit(PIDFD_PASS); + + if (pid2 == PID_RECYCLE) { + snprintf(buf, sizeof(buf), "/proc/%d", pid2); + ksft_print_msg("pid to recycle is %d\n", pid2); + pidfd = open(buf, O_DIRECTORY | O_CLOEXEC); + } + + if (wait_for_pid(pid2)) + _exit(PIDFD_ERROR); + + if (pid2 >= PID_RECYCLE) + break; + } + + /* + * We want to be as predictable as we can so if we haven't been + * able to grab pid PID_RECYCLE skip the test. + */ + if (pid2 != PID_RECYCLE) { + /* skip test */ + close(pidfd); + _exit(PIDFD_SKIP); + } + + if (pidfd < 0) + _exit(PIDFD_ERROR); + + for (i = 0; i <= PIDFD_MAX_DEFAULT; i++) { + char c; + int pipe_fds[2]; + pid_t recycled_pid; + int child_ret = PIDFD_PASS; + + ret = pipe2(pipe_fds, O_CLOEXEC); + if (ret < 0) + _exit(PIDFD_ERROR); + + recycled_pid = fork(); + if (recycled_pid < 0) + _exit(PIDFD_ERROR); + + if (recycled_pid == 0) { + close(pipe_fds[1]); + (void)read(pipe_fds[0], &c, 1); + close(pipe_fds[0]); + + _exit(PIDFD_PASS); + } + + /* + * Stop the child so we can inspect whether we have + * recycled pid PID_RECYCLE. + */ + close(pipe_fds[0]); + ret = kill(recycled_pid, SIGSTOP); + close(pipe_fds[1]); + if (ret) { + (void)wait_for_pid(recycled_pid); + _exit(PIDFD_ERROR); + } + + /* + * We have recycled the pid. Try to signal it. This + * needs to fail since this is a different process than + * the one the pidfd refers to. + */ + if (recycled_pid == PID_RECYCLE) { + ret = sys_pidfd_send_signal(pidfd, SIGCONT, + NULL, 0); + if (ret && errno == ESRCH) + child_ret = PIDFD_XFAIL; + else + child_ret = PIDFD_FAIL; + } + + /* let the process move on */ + ret = kill(recycled_pid, SIGCONT); + if (ret) + (void)kill(recycled_pid, SIGKILL); + + if (wait_for_pid(recycled_pid)) + _exit(PIDFD_ERROR); + + switch (child_ret) { + case PIDFD_FAIL: + /* fallthrough */ + case PIDFD_XFAIL: + _exit(child_ret); + case PIDFD_PASS: + break; + default: + /* not reached */ + _exit(PIDFD_ERROR); + } + + /* + * If the user set a custom pid_max limit we could be + * in the millions. + * Skip the test in this case. + */ + if (recycled_pid > PIDFD_MAX_DEFAULT) + _exit(PIDFD_SKIP); + } + + /* failed to recycle pid */ + _exit(PIDFD_SKIP); + } + + ret = wait_for_pid(pid1); + switch (ret) { + case PIDFD_FAIL: + ksft_exit_fail_msg( + "%s test: Managed to signal recycled pid %d\n", + test_name, PID_RECYCLE); + case PIDFD_PASS: + ksft_exit_fail_msg("%s test: Failed to recycle pid %d\n", + test_name, PID_RECYCLE); + case PIDFD_SKIP: + ksft_print_msg("%s test: Skipping test\n", test_name); + ret = 0; + break; + case PIDFD_XFAIL: + ksft_test_result_pass( + "%s test: Failed to signal recycled pid as expected\n", + test_name); + ret = 0; + break; + default /* PIDFD_ERROR */: + ksft_exit_fail_msg("%s test: Error while running tests\n", + test_name); + } + + return ret; +} + +static int test_pidfd_send_signal_syscall_support(void) +{ + int pidfd, ret; + const char *test_name = "pidfd_send_signal check for support"; + + 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); + + ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0); + if (ret < 0) { + /* + * pidfd_send_signal() will currently return ENOSYS when + * CONFIG_PROC_FS is not set. + */ + if (errno == ENOSYS) + ksft_exit_skip( + "%s test: pidfd_send_signal() syscall not supported (Ensure that CONFIG_PROC_FS=y is set)\n", + test_name); + + ksft_exit_fail_msg("%s test: Failed to send signal\n", + test_name); + } + + close(pidfd); + ksft_test_result_pass( + "%s test: pidfd_send_signal() syscall is supported. Tests can be executed\n", + test_name); + return 0; +} + +int main(int argc, char **argv) +{ + ksft_print_header(); + + test_pidfd_send_signal_syscall_support(); + test_pidfd_send_signal_simple_success(); + test_pidfd_send_signal_exited_fail(); + test_pidfd_send_signal_recycled_pid_fail(); + + return ksft_exit_pass(); +}

[v7,2/2] selftests: add tests for pidfd_send_signal()

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