On Sat, Dec 29, 2018 at 11:27:56PM +0100, Christian Brauner wrote:
> 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.dbf0508c2508138efc5f2...@linux-foundation.org/
>
> Cc: Arnd Bergmann <a...@arndb.de>
> Cc: "Eric W. Biederman" <ebied...@xmission.com>
> Cc: Kees Cook <keesc...@chromium.org>
> Cc: Serge Hallyn <se...@hallyn.com>
Acked-by: Serge Hallyn <se...@hallyn.com>
Not saying you need to do this, but it would be neat if you could test
sending to a pid which has been recycled :)
> Cc: Jann Horn <ja...@google.com>
> Cc: Andy Lutomirsky <l...@kernel.org>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Cc: Oleg Nesterov <o...@redhat.com>
> Cc: Aleksa Sarai <cyp...@cyphar.com>
> Cc: Al Viro <v...@zeniv.linux.org.uk>
> Cc: Florian Weimer <fwei...@redhat.com>
> Signed-off-by: Christian Brauner <christ...@brauner.io>
> ---
> /* 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
