Unverified Commit 7b6724fe authored by Christian Brauner's avatar Christian Brauner
Browse files

selftests/coredump: add tests for AF_UNIX coredumps 

Add a simple test for generating coredumps via AF_UNIX sockets.

Link: https://lore.kernel.org/20250516-work-coredump-socket-v8-9-664f3caf2516@kernel.org


Acked-by: default avatarLuca Boccassi <luca.boccassi@gmail.com>
Reviewed-by: default avatarAlexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 4d657594

tools/testing/selftests/coredump/stackdump_test.c

+466 −1
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#include <fcntl.h>

#include <inttypes.h>

#include <libgen.h>

#include <linux/limits.h>

#include <pthread.h>

#include <string.h>

#include <sys/mount.h>

#include <sys/resource.h>

#include <sys/stat.h>

#include <sys/socket.h>

#include <sys/un.h>

#include <unistd.h>



#include "../kselftest_harness.h"

#include "../pidfd/pidfd.h"



#define STACKDUMP_FILE "stack_values"

#define STACKDUMP_SCRIPT "stackdump"
@@ -35,6 +41,7 @@ static void crashing_child(void) 
FIXTURE(coredump)

{

	char original_core_pattern[256];

	pid_t pid_coredump_server;

};



FIXTURE_SETUP(coredump)
@@ -44,6 +51,7 @@ FIXTURE_SETUP(coredump) 
	char *dir;

	int ret;



	self->pid_coredump_server = -ESRCH;

	file = fopen("/proc/sys/kernel/core_pattern", "r");

	ASSERT_NE(NULL, file);
@@ -61,10 +69,17 @@ FIXTURE_TEARDOWN(coredump) 
{

	const char *reason;

	FILE *file;

	int ret;

	int ret, status;



	unlink(STACKDUMP_FILE);



	if (self->pid_coredump_server > 0) {

		kill(self->pid_coredump_server, SIGTERM);

		waitpid(self->pid_coredump_server, &status, 0);

	}

	unlink("/tmp/coredump.file");

	unlink("/tmp/coredump.socket");



	file = fopen("/proc/sys/kernel/core_pattern", "w");

	if (!file) {

		reason = "Unable to open core_pattern";
@@ -154,4 +169,454 @@ TEST_F_TIMEOUT(coredump, stackdump, 120) 
	fclose(file);

}



TEST_F(coredump, socket)

{

	int fd, pidfd, ret, status;

	FILE *file;

	pid_t pid, pid_coredump_server;

	struct stat st;

	char core_file[PATH_MAX];

	struct pidfd_info info = {};

	int ipc_sockets[2];

	char c;

	const struct sockaddr_un coredump_sk = {

		.sun_family = AF_UNIX,

		.sun_path = "/tmp/coredump.socket",

	};

	size_t coredump_sk_len = offsetof(struct sockaddr_un, sun_path) +

				 sizeof("/tmp/coredump.socket");



	ret = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets);

	ASSERT_EQ(ret, 0);



	file = fopen("/proc/sys/kernel/core_pattern", "w");

	ASSERT_NE(file, NULL);



	ret = fprintf(file, "@/tmp/coredump.socket");

	ASSERT_EQ(ret, strlen("@/tmp/coredump.socket"));

	ASSERT_EQ(fclose(file), 0);



	pid_coredump_server = fork();

	ASSERT_GE(pid_coredump_server, 0);

	if (pid_coredump_server == 0) {

		int fd_server, fd_coredump, fd_peer_pidfd, fd_core_file;

		socklen_t fd_peer_pidfd_len;



		close(ipc_sockets[0]);



		fd_server = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);

		if (fd_server < 0)

			_exit(EXIT_FAILURE);



		ret = bind(fd_server, (const struct sockaddr *)&coredump_sk, coredump_sk_len);

		if (ret < 0) {

			fprintf(stderr, "Failed to bind coredump socket\n");

			close(fd_server);

			close(ipc_sockets[1]);

			_exit(EXIT_FAILURE);

		}



		ret = listen(fd_server, 1);

		if (ret < 0) {

			fprintf(stderr, "Failed to listen on coredump socket\n");

			close(fd_server);

			close(ipc_sockets[1]);

			_exit(EXIT_FAILURE);

		}



		if (write_nointr(ipc_sockets[1], "1", 1) < 0) {

			close(fd_server);

			close(ipc_sockets[1]);

			_exit(EXIT_FAILURE);

		}



		close(ipc_sockets[1]);



		fd_coredump = accept4(fd_server, NULL, NULL, SOCK_CLOEXEC);

		if (fd_coredump < 0) {

			fprintf(stderr, "Failed to accept coredump socket connection\n");

			close(fd_server);

			_exit(EXIT_FAILURE);

		}



		fd_peer_pidfd_len = sizeof(fd_peer_pidfd);

		ret = getsockopt(fd_coredump, SOL_SOCKET, SO_PEERPIDFD,

				 &fd_peer_pidfd, &fd_peer_pidfd_len);

		if (ret < 0) {

			fprintf(stderr, "%m - Failed to retrieve peer pidfd for coredump socket connection\n");

			close(fd_coredump);

			close(fd_server);

			_exit(EXIT_FAILURE);

		}



		memset(&info, 0, sizeof(info));

		info.mask = PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP;

		ret = ioctl(fd_peer_pidfd, PIDFD_GET_INFO, &info);

		if (ret < 0) {

			fprintf(stderr, "Failed to retrieve pidfd info from peer pidfd for coredump socket connection\n");

			close(fd_coredump);

			close(fd_server);

			close(fd_peer_pidfd);

			_exit(EXIT_FAILURE);

		}



		if (!(info.mask & PIDFD_INFO_COREDUMP)) {

			fprintf(stderr, "Missing coredump information from coredumping task\n");

			close(fd_coredump);

			close(fd_server);

			close(fd_peer_pidfd);

			_exit(EXIT_FAILURE);

		}



		if (!(info.coredump_mask & PIDFD_COREDUMPED)) {

			fprintf(stderr, "Received connection from non-coredumping task\n");

			close(fd_coredump);

			close(fd_server);

			close(fd_peer_pidfd);

			_exit(EXIT_FAILURE);

		}



		fd_core_file = creat("/tmp/coredump.file", 0644);

		if (fd_core_file < 0) {

			fprintf(stderr, "Failed to create coredump file\n");

			close(fd_coredump);

			close(fd_server);

			close(fd_peer_pidfd);

			_exit(EXIT_FAILURE);

		}



		for (;;) {

			char buffer[4096];

			ssize_t bytes_read, bytes_write;



			bytes_read = read(fd_coredump, buffer, sizeof(buffer));

			if (bytes_read < 0) {

				close(fd_coredump);

				close(fd_server);

				close(fd_peer_pidfd);

				close(fd_core_file);

				_exit(EXIT_FAILURE);

			}



			if (bytes_read == 0)

				break;



			bytes_write = write(fd_core_file, buffer, bytes_read);

			if (bytes_read != bytes_write) {

				close(fd_coredump);

				close(fd_server);

				close(fd_peer_pidfd);

				close(fd_core_file);

				_exit(EXIT_FAILURE);

			}

		}



		close(fd_coredump);

		close(fd_server);

		close(fd_peer_pidfd);

		close(fd_core_file);

		_exit(EXIT_SUCCESS);

	}

	self->pid_coredump_server = pid_coredump_server;



	EXPECT_EQ(close(ipc_sockets[1]), 0);

	ASSERT_EQ(read_nointr(ipc_sockets[0], &c, 1), 1);

	EXPECT_EQ(close(ipc_sockets[0]), 0);



	pid = fork();

	ASSERT_GE(pid, 0);

	if (pid == 0)

		crashing_child();



	pidfd = sys_pidfd_open(pid, 0);

	ASSERT_GE(pidfd, 0);



	waitpid(pid, &status, 0);

	ASSERT_TRUE(WIFSIGNALED(status));

	ASSERT_TRUE(WCOREDUMP(status));



	info.mask = PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP;

	ASSERT_EQ(ioctl(pidfd, PIDFD_GET_INFO, &info), 0);

	ASSERT_GT((info.mask & PIDFD_INFO_COREDUMP), 0);

	ASSERT_GT((info.coredump_mask & PIDFD_COREDUMPED), 0);



	waitpid(pid_coredump_server, &status, 0);

	self->pid_coredump_server = -ESRCH;

	ASSERT_TRUE(WIFEXITED(status));

	ASSERT_EQ(WEXITSTATUS(status), 0);



	ASSERT_EQ(stat("/tmp/coredump.file", &st), 0);

	ASSERT_GT(st.st_size, 0);

	/*

	 * We should somehow validate the produced core file.

	 * For now just allow for visual inspection

	 */

	system("file /tmp/coredump.file");

}



TEST_F(coredump, socket_detect_userspace_client)

{

	int fd, pidfd, ret, status;

	FILE *file;

	pid_t pid, pid_coredump_server;

	struct stat st;

	char core_file[PATH_MAX];

	struct pidfd_info info = {};

	int ipc_sockets[2];

	char c;

	const struct sockaddr_un coredump_sk = {

		.sun_family = AF_UNIX,

		.sun_path = "/tmp/coredump.socket",

	};

	size_t coredump_sk_len = offsetof(struct sockaddr_un, sun_path) +

				 sizeof("/tmp/coredump.socket");



	file = fopen("/proc/sys/kernel/core_pattern", "w");

	ASSERT_NE(file, NULL);



	ret = fprintf(file, "@/tmp/coredump.socket");

	ASSERT_EQ(ret, strlen("@/tmp/coredump.socket"));

	ASSERT_EQ(fclose(file), 0);



	ret = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets);

	ASSERT_EQ(ret, 0);



	pid_coredump_server = fork();

	ASSERT_GE(pid_coredump_server, 0);

	if (pid_coredump_server == 0) {

		int fd_server, fd_coredump, fd_peer_pidfd, fd_core_file;

		socklen_t fd_peer_pidfd_len;



		close(ipc_sockets[0]);



		fd_server = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);

		if (fd_server < 0)

			_exit(EXIT_FAILURE);



		ret = bind(fd_server, (const struct sockaddr *)&coredump_sk, coredump_sk_len);

		if (ret < 0) {

			fprintf(stderr, "Failed to bind coredump socket\n");

			close(fd_server);

			close(ipc_sockets[1]);

			_exit(EXIT_FAILURE);

		}



		ret = listen(fd_server, 1);

		if (ret < 0) {

			fprintf(stderr, "Failed to listen on coredump socket\n");

			close(fd_server);

			close(ipc_sockets[1]);

			_exit(EXIT_FAILURE);

		}



		if (write_nointr(ipc_sockets[1], "1", 1) < 0) {

			close(fd_server);

			close(ipc_sockets[1]);

			_exit(EXIT_FAILURE);

		}



		close(ipc_sockets[1]);



		fd_coredump = accept4(fd_server, NULL, NULL, SOCK_CLOEXEC);

		if (fd_coredump < 0) {

			fprintf(stderr, "Failed to accept coredump socket connection\n");

			close(fd_server);

			_exit(EXIT_FAILURE);

		}



		fd_peer_pidfd_len = sizeof(fd_peer_pidfd);

		ret = getsockopt(fd_coredump, SOL_SOCKET, SO_PEERPIDFD,

				 &fd_peer_pidfd, &fd_peer_pidfd_len);

		if (ret < 0) {

			fprintf(stderr, "%m - Failed to retrieve peer pidfd for coredump socket connection\n");

			close(fd_coredump);

			close(fd_server);

			_exit(EXIT_FAILURE);

		}



		memset(&info, 0, sizeof(info));

		info.mask = PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP;

		ret = ioctl(fd_peer_pidfd, PIDFD_GET_INFO, &info);

		if (ret < 0) {

			fprintf(stderr, "Failed to retrieve pidfd info from peer pidfd for coredump socket connection\n");

			close(fd_coredump);

			close(fd_server);

			close(fd_peer_pidfd);

			_exit(EXIT_FAILURE);

		}



		if (!(info.mask & PIDFD_INFO_COREDUMP)) {

			fprintf(stderr, "Missing coredump information from coredumping task\n");

			close(fd_coredump);

			close(fd_server);

			close(fd_peer_pidfd);

			_exit(EXIT_FAILURE);

		}



		if (info.coredump_mask & PIDFD_COREDUMPED) {

			fprintf(stderr, "Received unexpected connection from coredumping task\n");

			close(fd_coredump);

			close(fd_server);

			close(fd_peer_pidfd);

			_exit(EXIT_FAILURE);

		}



		close(fd_coredump);

		close(fd_server);

		close(fd_peer_pidfd);

		close(fd_core_file);

		_exit(EXIT_SUCCESS);

	}

	self->pid_coredump_server = pid_coredump_server;



	EXPECT_EQ(close(ipc_sockets[1]), 0);

	ASSERT_EQ(read_nointr(ipc_sockets[0], &c, 1), 1);

	EXPECT_EQ(close(ipc_sockets[0]), 0);



	pid = fork();

	ASSERT_GE(pid, 0);

	if (pid == 0) {

		int fd_socket;

		ssize_t ret;



		fd_socket = socket(AF_UNIX, SOCK_STREAM, 0);

		if (fd_socket < 0)

			_exit(EXIT_FAILURE);





		ret = connect(fd_socket, (const struct sockaddr *)&coredump_sk, coredump_sk_len);

		if (ret < 0)

			_exit(EXIT_FAILURE);



		(void *)write(fd_socket, &(char){ 0 }, 1);

		close(fd_socket);

		_exit(EXIT_SUCCESS);

	}



	pidfd = sys_pidfd_open(pid, 0);

	ASSERT_GE(pidfd, 0);



	waitpid(pid, &status, 0);

	ASSERT_TRUE(WIFEXITED(status));

	ASSERT_EQ(WEXITSTATUS(status), 0);



	info.mask = PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP;

	ASSERT_EQ(ioctl(pidfd, PIDFD_GET_INFO, &info), 0);

	ASSERT_GT((info.mask & PIDFD_INFO_COREDUMP), 0);

	ASSERT_EQ((info.coredump_mask & PIDFD_COREDUMPED), 0);



	waitpid(pid_coredump_server, &status, 0);

	self->pid_coredump_server = -ESRCH;

	ASSERT_TRUE(WIFEXITED(status));

	ASSERT_EQ(WEXITSTATUS(status), 0);



	ASSERT_NE(stat("/tmp/coredump.file", &st), 0);

	ASSERT_EQ(errno, ENOENT);

}



TEST_F(coredump, socket_enoent)

{

	int pidfd, ret, status;

	FILE *file;

	pid_t pid;

	char core_file[PATH_MAX];



	file = fopen("/proc/sys/kernel/core_pattern", "w");

	ASSERT_NE(file, NULL);



	ret = fprintf(file, "@/tmp/coredump.socket");

	ASSERT_EQ(ret, strlen("@/tmp/coredump.socket"));

	ASSERT_EQ(fclose(file), 0);



	pid = fork();

	ASSERT_GE(pid, 0);

	if (pid == 0)

		crashing_child();



	pidfd = sys_pidfd_open(pid, 0);

	ASSERT_GE(pidfd, 0);



	waitpid(pid, &status, 0);

	ASSERT_TRUE(WIFSIGNALED(status));

	ASSERT_FALSE(WCOREDUMP(status));

}



TEST_F(coredump, socket_no_listener)

{

	int pidfd, ret, status;

	FILE *file;

	pid_t pid, pid_coredump_server;

	int ipc_sockets[2];

	char c;

	const struct sockaddr_un coredump_sk = {

		.sun_family = AF_UNIX,

		.sun_path = "/tmp/coredump.socket",

	};

	size_t coredump_sk_len = offsetof(struct sockaddr_un, sun_path) +

				 sizeof("/tmp/coredump.socket");



	ret = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets);

	ASSERT_EQ(ret, 0);



	file = fopen("/proc/sys/kernel/core_pattern", "w");

	ASSERT_NE(file, NULL);



	ret = fprintf(file, "@/tmp/coredump.socket");

	ASSERT_EQ(ret, strlen("@/tmp/coredump.socket"));

	ASSERT_EQ(fclose(file), 0);



	pid_coredump_server = fork();

	ASSERT_GE(pid_coredump_server, 0);

	if (pid_coredump_server == 0) {

		int fd_server;

		socklen_t fd_peer_pidfd_len;



		close(ipc_sockets[0]);



		fd_server = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);

		if (fd_server < 0)

			_exit(EXIT_FAILURE);



		ret = bind(fd_server, (const struct sockaddr *)&coredump_sk, coredump_sk_len);

		if (ret < 0) {

			fprintf(stderr, "Failed to bind coredump socket\n");

			close(fd_server);

			close(ipc_sockets[1]);

			_exit(EXIT_FAILURE);

		}



		if (write_nointr(ipc_sockets[1], "1", 1) < 0) {

			close(fd_server);

			close(ipc_sockets[1]);

			_exit(EXIT_FAILURE);

		}



		close(fd_server);

		close(ipc_sockets[1]);

		_exit(EXIT_SUCCESS);

	}

	self->pid_coredump_server = pid_coredump_server;



	EXPECT_EQ(close(ipc_sockets[1]), 0);

	ASSERT_EQ(read_nointr(ipc_sockets[0], &c, 1), 1);

	EXPECT_EQ(close(ipc_sockets[0]), 0);



	pid = fork();

	ASSERT_GE(pid, 0);

	if (pid == 0)

		crashing_child();



	pidfd = sys_pidfd_open(pid, 0);

	ASSERT_GE(pidfd, 0);



	waitpid(pid, &status, 0);

	ASSERT_TRUE(WIFSIGNALED(status));

	ASSERT_FALSE(WCOREDUMP(status));



	waitpid(pid_coredump_server, &status, 0);

	self->pid_coredump_server = -ESRCH;

	ASSERT_TRUE(WIFEXITED(status));

	ASSERT_EQ(WEXITSTATUS(status), 0);

}



TEST_HARNESS_MAIN