Re: [PATCH v2] selftests: add tests for clone3()

On Mon, Nov 04, 2019 at 02:18:46PM +0100, Adrian Reber wrote:

This adds tests for clone3() with different values and sizes of struct clone_args.

This selftest was initially part of of the clone3() with PID selftest. After that patch was almost merged Eugene sent out a couple of patches to fix problems with these test.

This commit now only contains the clone3() selftest after the LPC decision to rework clone3() with PID to allow setting the PID in multiple PID namespaces including all of Eugene's patches.

Signed-off-by: Eugene Syromiatnikov esyr@redhat.com Signed-off-by: Adrian Reber areber@redhat.com

Resending, since mutt messed-up the quoting due to a new configuration I was testing.

A few more comments below.

Also, would you be open to adding tests here for the newly added .stack and .stack_size API (cf. [1])?

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

---

v2:

• Applied Christian's suggestions
• Skip root-only tests when running as non-root

---

MAINTAINERS | 1 + tools/testing/selftests/Makefile | 1 + tools/testing/selftests/clone3/.gitignore | 1 + tools/testing/selftests/clone3/Makefile | 7 + tools/testing/selftests/clone3/clone3.c | 225 ++++++++++++++++++++++ 5 files changed, 235 insertions(+) create mode 100644 tools/testing/selftests/clone3/.gitignore create mode 100644 tools/testing/selftests/clone3/Makefile create mode 100644 tools/testing/selftests/clone3/clone3.c

diff --git a/MAINTAINERS b/MAINTAINERS index cba1095547fd..0040b7a6410b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12829,6 +12829,7 @@ S: Maintained T: git git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git F: samples/pidfd/ F: tools/testing/selftests/pidfd/ +F: tools/testing/selftests/clone3/ K: (?i)pidfd K: (?i)clone3 K: \b(clone_args|kernel_clone_args)\b diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 4cdbae6f4e61..ad442364218a 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -4,6 +4,7 @@ TARGETS += bpf TARGETS += breakpoints TARGETS += capabilities TARGETS += cgroup +TARGETS += clone3 TARGETS += cpufreq TARGETS += cpu-hotplug TARGETS += drivers/dma-buf diff --git a/tools/testing/selftests/clone3/.gitignore b/tools/testing/selftests/clone3/.gitignore new file mode 100644 index 000000000000..85d9d3ba2524 --- /dev/null +++ b/tools/testing/selftests/clone3/.gitignore @@ -0,0 +1 @@ +clone3 diff --git a/tools/testing/selftests/clone3/Makefile b/tools/testing/selftests/clone3/Makefile new file mode 100644 index 000000000000..ea922c014ae4 --- /dev/null +++ b/tools/testing/selftests/clone3/Makefile @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: GPL-2.0

+CFLAGS += -I../../../../usr/include/

+TEST_GEN_PROGS := clone3

+include ../lib.mk diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c new file mode 100644 index 000000000000..a982d95189bf --- /dev/null +++ b/tools/testing/selftests/clone3/clone3.c @@ -0,0 +1,225 @@ +// SPDX-License-Identifier: GPL-2.0

+/* Based on Christian Brauner's clone3() example */

+#define _GNU_SOURCE +#include <errno.h> +#include <inttypes.h> +#include <linux/types.h> +#include <linux/sched.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <sys/syscall.h> +#include <sys/types.h> +#include <sys/un.h> +#include <sys/wait.h> +#include <unistd.h> +#include <sched.h>

+#include "../kselftest.h"

+/*

• • Different sizes of struct clone_args
• */

+#ifndef CLONE3_ARGS_SIZE_V0 +#define CLONE3_ARGS_SIZE_V0 64 +#endif

+enum test_mode {

• CLONE3_ARGS_NO_TEST,
• CLONE3_ARGS_ALL_0,
• CLONE3_ARGS_ALL_1,
• CLONE3_ARGS_INVAL_EXIT_SIGNAL_BIG,
• CLONE3_ARGS_INVAL_EXIT_SIGNAL_NEG,
• CLONE3_ARGS_INVAL_EXIT_SIGNAL_CSIG,
• CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG,

+};

+static pid_t raw_clone(struct clone_args *args, size_t size) +{

• return syscall(__NR_clone3, args, size);

+}

+static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode) +{

• struct clone_args args = {

• .flags = flags,
  

• .exit_signal = SIGCHLD,
  

• };
• struct clone_args_extended {

• struct clone_args args;
  

• __aligned_u64 excess_space[2];
  

• } args_ext;
• pid_t pid = -1;
• int status;
• memset(&args_ext, 0, sizeof(args_ext));
• if (size > sizeof(struct clone_args))

• args_ext.excess_space[1] = 1;
  

• if (size == 0)

• size = sizeof(struct clone_args);
  

• switch (test_mode) {
• case CLONE3_ARGS_ALL_0:

• args.flags = 0;
  

• args.exit_signal = 0;
  

• break;
  

• case CLONE3_ARGS_ALL_1:

I don't fully understand this test case. What is this for exactly?

• args.flags = 1;
  

• args.pidfd = 1;
  

• args.child_tid = 1;
  

• args.parent_tid = 1;
  

• args.exit_signal = 1;
  

• args.stack = 1;
  

• args. stack_size = 1;
  

• args.tls = 1;
  

• break;
  

• case CLONE3_ARGS_INVAL_EXIT_SIGNAL_BIG:

• args.exit_signal = 0xbadc0ded00000000ULL;
  

• break;
  

• case CLONE3_ARGS_INVAL_EXIT_SIGNAL_NEG:

• args.exit_signal = 0x0000000080000000ULL;
  

• break;
  

• case CLONE3_ARGS_INVAL_EXIT_SIGNAL_CSIG:

• args.exit_signal = 0x0000000000000100ULL;
  

• break;
  

• case CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG:

• args.exit_signal = 0x00000000000000f0ULL;
  

• break;
  

• }
• memcpy(&args_ext.args, &args, sizeof(struct clone_args));
• pid = raw_clone((struct clone_args *)&args_ext, size);
• if (pid < 0) {

• ksft_print_msg("%s - Failed to create new process\n",
  

• 		strerror(errno));
  

• return -errno;
  

• }
• if (pid == 0) {

• ksft_print_msg("I am the child, my PID is %d\n", getpid());
  

• _exit(EXIT_SUCCESS);
  

• }
• ksft_print_msg("I am the parent (%d). My child's pid is %d\n",

• 	getpid(), pid);
  

• if (wait(&status) < 0) {

• ksft_print_msg("Child returned %s\n", strerror(errno));
  

• return -errno;
  

• }
• if (WEXITSTATUS(status))

• return WEXITSTATUS(status);
  

• return 0;

+}

+static void test_clone3(uint64_t flags, size_t size, int expected,

•        enum test_mode test_mode)
  

+{

• int ret;
• ksft_print_msg(

• "[%d] Trying clone3() with flags %#" PRIx64 " (size %zu)\n",
  

• getpid(), flags, size);
  

• ret = call_clone3(flags, size, test_mode);
• ksft_print_msg("[%d] clone3() with flags says: %d expected %d\n",

• 	getpid(), ret, expected);
  

• if (ret != expected)

• ksft_test_result_fail(
  

• 	"[%d] Result (%d) is different than expected (%d)\n",
  

• 	getpid(), ret, expected);
  

• else

• ksft_test_result_pass(
  

• 	"[%d] Result (%d) matches expectation (%d)\n",
  

• 	getpid(), ret, expected);
  

+} +int main(int argc, char *argv[]) +{

• pid_t pid;
• uid_t uid = getuid();
• ksft_print_header();
• ksft_set_plan(17);
• /* Just a simple clone3() should return 0.*/
• test_clone3(0, 0, 0, CLONE3_ARGS_NO_TEST);
• /* Do a clone3() in a new PID NS.*/
• if (uid == 0)

• test_clone3(CLONE_NEWPID, 0, 0, CLONE3_ARGS_NO_TEST);
  

• else

• ksft_test_result_skip("Skipping clone3() with CLONE_NEWPID\n");
  

• /* Do a clone3() with CLONE3_ARGS_SIZE_V0. */
• test_clone3(0, CLONE3_ARGS_SIZE_V0, 0, CLONE3_ARGS_NO_TEST);
• /* Do a clone3() with CLONE3_ARGS_SIZE_V0 - 8 */
• test_clone3(0, CLONE3_ARGS_SIZE_V0 - 8, -EINVAL, CLONE3_ARGS_NO_TEST);
• /* Do a clone3() with sizeof(struct clone_args) + 8 */
• test_clone3(0, sizeof(struct clone_args) + 8, 0, CLONE3_ARGS_NO_TEST);
• /* Do a clone3() with all members set to 1 */
• test_clone3(0, 0, -EINVAL, CLONE3_ARGS_ALL_1);
• /* Do a clone3() with exit_signal having highest 32 bits non-zero */
• test_clone3(0, 0, -EINVAL, CLONE3_ARGS_INVAL_EXIT_SIGNAL_BIG);
• /* Do a clone3() with negative 32-bit exit_signal */
• test_clone3(0, 0, -EINVAL, CLONE3_ARGS_INVAL_EXIT_SIGNAL_NEG);
• /* Do a clone3() with exit_signal not fitting into CSIGNAL mask */
• test_clone3(0, 0, -EINVAL, CLONE3_ARGS_INVAL_EXIT_SIGNAL_CSIG);
• /* Do a clone3() with NSIG < exit_signal < CSIG */
• test_clone3(0, 0, -EINVAL, CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG);
• /*

• * Do a clone3() with sizeof(struct clone_args) + 8
  

• * and all members set to 0. This resets exit_signal and wait()
  

• * will not get a result.
  

• */
  

• test_clone3(0, sizeof(struct clone_args) + 8, -ECHILD,

• 	CLONE3_ARGS_ALL_0);
  

Ah, I haven't caught this during the first review. No, that's not correct. You don't get a signal since exit_signal is 0, that's correct _but_ you still need to wait on the child. You don't see the child because the kernel will by default not wait on clone()-children aka processes created with exit_signal != SIGCHLD. To wait on clone()-children as well, you need to set __WCLONE or __WALL in the options argument for wait{p}id(2).

• /*

• * Do a clone3() with sizeof(struct clone_args) + 8
  

• * and all members set to 0.
  

• */
  

• test_clone3(0, sizeof(struct clone_args) + 8, -EINVAL,

• 	CLONE3_ARGS_ALL_1);
  

The comment and the test don't line up. :)

• /* Do a clone3() with > page size */
• test_clone3(0, getpagesize() + 8, -E2BIG, CLONE3_ARGS_NO_TEST);
• /* Do a clone3() with CLONE3_ARGS_SIZE_V0 in a new PID NS. */
• if (uid == 0)

• test_clone3(CLONE_NEWPID, CLONE3_ARGS_SIZE_V0, 0,
  

• 		CLONE3_ARGS_NO_TEST);
  

• else

• ksft_test_result_skip("Skipping clone3() with CLONE_NEWPID\n");
  

• /* Do a clone3() with CLONE3_ARGS_SIZE_V0 - 8 in a new PID NS */
• test_clone3(CLONE_NEWPID, CLONE3_ARGS_SIZE_V0 - 8, -EINVAL,

• 	CLONE3_ARGS_NO_TEST);
  

• /* Do a clone3() with sizeof(struct clone_args) + 8 in a new PID NS */
• if (uid == 0)

• test_clone3(CLONE_NEWPID, sizeof(struct clone_args) + 8, 0,
  

• 		CLONE3_ARGS_NO_TEST);
  

• else

• ksft_test_result_skip("Skipping clone3() with CLONE_NEWPID\n");
  

• /* Do a clone3() with > page size in a new PID NS */
• test_clone3(CLONE_NEWPID, getpagesize() + 8, -E2BIG,

• 	CLONE3_ARGS_NO_TEST);
  

• return !ksft_get_fail_cnt() ? ksft_exit_pass() : ksft_exit_fail();

+}

2.23.0