Re: [PATCH v7 9/9] selftests/coredump: add tests for AF_UNIX coredumps
From: Alexander Mikhalitsyn <hidden>
Date: 2025-05-15 14:37:53
Also in:
linux-fsdevel, linux-security-module, lkml
Am Do., 15. Mai 2025 um 00:04 Uhr schrieb Christian Brauner [off-list ref]:
Add a simple test for generating coredumps via AF_UNIX sockets. Signed-off-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Alexander Mikhalitsyn <redacted>
quoted hunk ↗ jump to hunk
--- tools/testing/selftests/coredump/stackdump_test.c | 514 +++++++++++++++++++++- 1 file changed, 513 insertions(+), 1 deletion(-)diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/testing/selftests/coredump/stackdump_test.c index fe3c728cd6be..42ddcf0bdaf2 100644 --- a/tools/testing/selftests/coredump/stackdump_test.c +++ b/tools/testing/selftests/coredump/stackdump_test.c@@ -1,14 +1,20 @@ // 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 +169,501 @@ 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; + __u64 peer_cookie; + socklen_t fd_peer_pidfd_len, peer_cookie_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); + } + + peer_cookie_len = sizeof(peer_cookie); + ret = getsockopt(fd_coredump, SOL_SOCKET, SO_COOKIE, + &peer_cookie, &peer_cookie_len); + if (ret < 0) { + fprintf(stderr, "%m - Failed to retrieve cookie for coredump socket connection\n"); + close(fd_coredump); + 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); + } + + if (!info.coredump_cookie) { + fprintf(stderr, "Missing coredump cookie\n"); + close(fd_coredump); + close(fd_server); + close(fd_peer_pidfd); + _exit(EXIT_FAILURE); + } + + if (info.coredump_cookie != peer_cookie) { + fprintf(stderr, "Mismatching coredump cookies\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; + __u64 peer_cookie; + socklen_t fd_peer_pidfd_len, peer_cookie_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); + } + + peer_cookie_len = sizeof(peer_cookie); + ret = getsockopt(fd_coredump, SOL_SOCKET, SO_COOKIE, + &peer_cookie, &peer_cookie_len); + if (ret < 0) { + fprintf(stderr, "%m - Failed to retrieve cookie for coredump socket connection\n"); + close(fd_coredump); + 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); + } + + if (info.coredump_cookie) { + fprintf(stderr, "Received unexpected coredump cookie\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, fd_coredump, fd_peer_pidfd, fd_core_file; + __u64 peer_cookie; + socklen_t fd_peer_pidfd_len, peer_cookie_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 --2.47.2