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Christian Brauner
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tests: test CLONE_CLEAR_SIGHAND
Test that CLONE_CLEAR_SIGHAND resets signal handlers to SIG_DFL for the child process and that CLONE_CLEAR_SIGHAND and CLONE_SIGHAND are mutually exclusive. Cc: Florian Weimer <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Christian Brauner <[email protected]> Link: https://lore.kernel.org/r/[email protected]
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‎MAINTAINERS‎

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@@ -12826,6 +12826,7 @@ S: Maintained
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T: git git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git
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F: samples/pidfd/
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F: tools/testing/selftests/pidfd/
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F: tools/testing/selftests/clone3/
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K: (?i)pidfd
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K: (?i)clone3
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K: \b(clone_args|kernel_clone_args)\b

‎tools/testing/selftests/Makefile‎

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@@ -4,6 +4,7 @@ TARGETS += bpf
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TARGETS += breakpoints
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TARGETS += capabilities
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TARGETS += cgroup
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TARGETS += clone3
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TARGETS += cpufreq
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TARGETS += cpu-hotplug
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TARGETS += drivers/dma-buf

‎tools/testing/selftests/clone3/.gitignore‎

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clone3_clear_sighand

‎tools/testing/selftests/clone3/Makefile‎

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# SPDX-License-Identifier: GPL-2.0-only
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CFLAGS += -g -I../../../../usr/include/
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TEST_GEN_PROGS := clone3_clear_sighand
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include ../lib.mk

‎tools/testing/selftests/clone3/clone3_clear_sighand.c‎

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/* SPDX-License-Identifier: GPL-2.0 */
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#define _GNU_SOURCE
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#include <errno.h>
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#include <sched.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <linux/sched.h>
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#include <linux/types.h>
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#include <sys/syscall.h>
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#include <sys/wait.h>
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#include "../kselftest.h"
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#ifndef CLONE_CLEAR_SIGHAND
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#define CLONE_CLEAR_SIGHAND 0x100000000ULL
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#endif
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#ifndef __NR_clone3
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#define __NR_clone3 -1
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struct clone_args {
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__aligned_u64 flags;
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__aligned_u64 pidfd;
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__aligned_u64 child_tid;
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__aligned_u64 parent_tid;
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__aligned_u64 exit_signal;
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__aligned_u64 stack;
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__aligned_u64 stack_size;
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__aligned_u64 tls;
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};
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#endif
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static pid_t sys_clone3(struct clone_args *args, size_t size)
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{
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return syscall(__NR_clone3, args, size);
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}
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static void test_clone3_supported(void)
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{
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pid_t pid;
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struct clone_args args = {};
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if (__NR_clone3 < 0)
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ksft_exit_skip("clone3() syscall is not supported\n");
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/* Set to something that will always cause EINVAL. */
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args.exit_signal = -1;
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pid = sys_clone3(&args, sizeof(args));
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if (!pid)
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exit(EXIT_SUCCESS);
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if (pid > 0) {
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wait(NULL);
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ksft_exit_fail_msg(
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"Managed to create child process with invalid exit_signal\n");
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}
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if (errno == ENOSYS)
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ksft_exit_skip("clone3() syscall is not supported\n");
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ksft_print_msg("clone3() syscall supported\n");
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}
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static void nop_handler(int signo)
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{
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}
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static int wait_for_pid(pid_t pid)
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{
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int status, ret;
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again:
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ret = waitpid(pid, &status, 0);
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if (ret == -1) {
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if (errno == EINTR)
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goto again;
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return -1;
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}
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if (!WIFEXITED(status))
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return -1;
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return WEXITSTATUS(status);
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}
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static void test_clone3_clear_sighand(void)
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{
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int ret;
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pid_t pid;
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struct clone_args args = {};
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struct sigaction act;
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/*
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* Check that CLONE_CLEAR_SIGHAND and CLONE_SIGHAND are mutually
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* exclusive.
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*/
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args.flags |= CLONE_CLEAR_SIGHAND | CLONE_SIGHAND;
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args.exit_signal = SIGCHLD;
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pid = sys_clone3(&args, sizeof(args));
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if (pid > 0)
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ksft_exit_fail_msg(
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"clone3(CLONE_CLEAR_SIGHAND | CLONE_SIGHAND) succeeded\n");
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act.sa_handler = nop_handler;
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ret = sigemptyset(&act.sa_mask);
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if (ret < 0)
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ksft_exit_fail_msg("%s - sigemptyset() failed\n",
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strerror(errno));
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act.sa_flags = 0;
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/* Register signal handler for SIGUSR1 */
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ret = sigaction(SIGUSR1, &act, NULL);
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if (ret < 0)
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ksft_exit_fail_msg(
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"%s - sigaction(SIGUSR1, &act, NULL) failed\n",
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strerror(errno));
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/* Register signal handler for SIGUSR2 */
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ret = sigaction(SIGUSR2, &act, NULL);
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if (ret < 0)
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ksft_exit_fail_msg(
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"%s - sigaction(SIGUSR2, &act, NULL) failed\n",
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strerror(errno));
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/* Check that CLONE_CLEAR_SIGHAND works. */
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args.flags = CLONE_CLEAR_SIGHAND;
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pid = sys_clone3(&args, sizeof(args));
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if (pid < 0)
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ksft_exit_fail_msg("%s - clone3(CLONE_CLEAR_SIGHAND) failed\n",
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strerror(errno));
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if (pid == 0) {
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ret = sigaction(SIGUSR1, NULL, &act);
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if (ret < 0)
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exit(EXIT_FAILURE);
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if (act.sa_handler != SIG_DFL)
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exit(EXIT_FAILURE);
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ret = sigaction(SIGUSR2, NULL, &act);
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if (ret < 0)
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exit(EXIT_FAILURE);
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if (act.sa_handler != SIG_DFL)
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exit(EXIT_FAILURE);
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exit(EXIT_SUCCESS);
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}
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ret = wait_for_pid(pid);
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if (ret)
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ksft_exit_fail_msg(
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"Failed to clear signal handler for child process\n");
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ksft_test_result_pass("Cleared signal handlers for child process\n");
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}
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int main(int argc, char **argv)
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{
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ksft_print_header();
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ksft_set_plan(1);
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test_clone3_supported();
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test_clone3_clear_sighand();
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return ksft_exit_pass();
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}

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