@@ -26,6 +26,7 @@ reuseport_bpf_cpu
reuseport_bpf_numa
reuseport_dualstack
rxtimestamp
+scm_pidfd
sk_bind_sendto_listen
sk_connect_zero_addr
socket
@@ -1,3 +1,4 @@
-TEST_GEN_PROGS := diag_uid test_unix_oob unix_connect
+CFLAGS += $(KHDR_INCLUDES)
+TEST_GEN_PROGS := diag_uid test_unix_oob unix_connect scm_pidfd
include ../../lib.mk
new file mode 100644
@@ -0,0 +1,430 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+#define _GNU_SOURCE
+#include <error.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <linux/socket.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/un.h>
+#include <sys/signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "../../kselftest_harness.h"
+
+#define clean_errno() (errno == 0 ? "None" : strerror(errno))
+#define log_err(MSG, ...) \
+ fprintf(stderr, "(%s:%d: errno: %s) " MSG "\n", __FILE__, __LINE__, \
+ clean_errno(), ##__VA_ARGS__)
+
+#ifndef SCM_PIDFD
+#define SCM_PIDFD 0x04
+#endif
+
+static void child_die()
+{
+ exit(1);
+}
+
+static int safe_int(const char *numstr, int *converted)
+{
+ char *err = NULL;
+ long sli;
+
+ errno = 0;
+ sli = strtol(numstr, &err, 0);
+ if (errno == ERANGE && (sli == LONG_MAX || sli == LONG_MIN))
+ return -ERANGE;
+
+ if (errno != 0 && sli == 0)
+ return -EINVAL;
+
+ if (err == numstr || *err != '\0')
+ return -EINVAL;
+
+ if (sli > INT_MAX || sli < INT_MIN)
+ return -ERANGE;
+
+ *converted = (int)sli;
+ return 0;
+}
+
+static int char_left_gc(const char *buffer, size_t len)
+{
+ size_t i;
+
+ for (i = 0; i < len; i++) {
+ if (buffer[i] == ' ' || buffer[i] == '\t')
+ continue;
+
+ return i;
+ }
+
+ return 0;
+}
+
+static int char_right_gc(const char *buffer, size_t len)
+{
+ int i;
+
+ for (i = len - 1; i >= 0; i--) {
+ if (buffer[i] == ' ' || buffer[i] == '\t' ||
+ buffer[i] == '\n' || buffer[i] == '\0')
+ continue;
+
+ return i + 1;
+ }
+
+ return 0;
+}
+
+static char *trim_whitespace_in_place(char *buffer)
+{
+ buffer += char_left_gc(buffer, strlen(buffer));
+ buffer[char_right_gc(buffer, strlen(buffer))] = '\0';
+ return buffer;
+}
+
+/* borrowed (with all helpers) from pidfd/pidfd_open_test.c */
+static pid_t get_pid_from_fdinfo_file(int pidfd, const char *key, size_t keylen)
+{
+ int ret;
+ char path[512];
+ FILE *f;
+ size_t n = 0;
+ pid_t result = -1;
+ char *line = NULL;
+
+ snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", pidfd);
+
+ f = fopen(path, "re");
+ if (!f)
+ return -1;
+
+ while (getline(&line, &n, f) != -1) {
+ char *numstr;
+
+ if (strncmp(line, key, keylen))
+ continue;
+
+ numstr = trim_whitespace_in_place(line + 4);
+ ret = safe_int(numstr, &result);
+ if (ret < 0)
+ goto out;
+
+ break;
+ }
+
+out:
+ free(line);
+ fclose(f);
+ return result;
+}
+
+static int cmsg_check(int fd)
+{
+ struct msghdr msg = { 0 };
+ struct cmsghdr *cmsg;
+ struct iovec iov;
+ struct ucred *ucred = NULL;
+ int data = 0;
+ char control[CMSG_SPACE(sizeof(struct ucred)) +
+ CMSG_SPACE(sizeof(int))] = { 0 };
+ int *pidfd = NULL;
+ pid_t parent_pid;
+ int err;
+
+ iov.iov_base = &data;
+ iov.iov_len = sizeof(data);
+
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ msg.msg_control = control;
+ msg.msg_controllen = sizeof(control);
+
+ err = recvmsg(fd, &msg, 0);
+ if (err < 0) {
+ log_err("recvmsg");
+ return 1;
+ }
+
+ if (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC)) {
+ log_err("recvmsg: truncated");
+ return 1;
+ }
+
+ for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
+ cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+ if (cmsg->cmsg_level == SOL_SOCKET &&
+ cmsg->cmsg_type == SCM_PIDFD) {
+ if (cmsg->cmsg_len < sizeof(*pidfd)) {
+ log_err("CMSG parse: SCM_PIDFD wrong len");
+ return 1;
+ }
+
+ pidfd = (void *)CMSG_DATA(cmsg);
+ }
+
+ if (cmsg->cmsg_level == SOL_SOCKET &&
+ cmsg->cmsg_type == SCM_CREDENTIALS) {
+ if (cmsg->cmsg_len < sizeof(*ucred)) {
+ log_err("CMSG parse: SCM_CREDENTIALS wrong len");
+ return 1;
+ }
+
+ ucred = (void *)CMSG_DATA(cmsg);
+ }
+ }
+
+ /* send(pfd, "x", sizeof(char), 0) */
+ if (data != 'x') {
+ log_err("recvmsg: data corruption");
+ return 1;
+ }
+
+ if (!pidfd) {
+ log_err("CMSG parse: SCM_PIDFD not found");
+ return 1;
+ }
+
+ if (!ucred) {
+ log_err("CMSG parse: SCM_CREDENTIALS not found");
+ return 1;
+ }
+
+ /* pidfd from SCM_PIDFD should point to the parent process PID */
+ parent_pid =
+ get_pid_from_fdinfo_file(*pidfd, "Pid:", sizeof("Pid:") - 1);
+ if (parent_pid != getppid()) {
+ log_err("wrong SCM_PIDFD %d != %d", parent_pid, getppid());
+ return 1;
+ }
+
+ return 0;
+}
+
+struct sock_addr {
+ char sock_name[32];
+ struct sockaddr_un listen_addr;
+ socklen_t addrlen;
+};
+
+FIXTURE(scm_pidfd)
+{
+ int server;
+ pid_t client_pid;
+ int startup_pipe[2];
+ struct sock_addr server_addr;
+ struct sock_addr *client_addr;
+};
+
+FIXTURE_VARIANT(scm_pidfd)
+{
+ int type;
+ bool abstract;
+};
+
+FIXTURE_VARIANT_ADD(scm_pidfd, stream_pathname)
+{
+ .type = SOCK_STREAM,
+ .abstract = 0,
+};
+
+FIXTURE_VARIANT_ADD(scm_pidfd, stream_abstract)
+{
+ .type = SOCK_STREAM,
+ .abstract = 1,
+};
+
+FIXTURE_VARIANT_ADD(scm_pidfd, dgram_pathname)
+{
+ .type = SOCK_DGRAM,
+ .abstract = 0,
+};
+
+FIXTURE_VARIANT_ADD(scm_pidfd, dgram_abstract)
+{
+ .type = SOCK_DGRAM,
+ .abstract = 1,
+};
+
+FIXTURE_SETUP(scm_pidfd)
+{
+ self->client_addr = mmap(NULL, sizeof(*self->client_addr), PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+ ASSERT_NE(MAP_FAILED, self->client_addr);
+}
+
+FIXTURE_TEARDOWN(scm_pidfd)
+{
+ close(self->server);
+
+ kill(self->client_pid, SIGKILL);
+ waitpid(self->client_pid, NULL, 0);
+
+ if (!variant->abstract) {
+ unlink(self->server_addr.sock_name);
+ unlink(self->client_addr->sock_name);
+ }
+}
+
+static void fill_sockaddr(struct sock_addr *addr, bool abstract)
+{
+ char *sun_path_buf = (char *)&addr->listen_addr.sun_path;
+
+ addr->listen_addr.sun_family = AF_UNIX;
+ addr->addrlen = offsetof(struct sockaddr_un, sun_path);
+ snprintf(addr->sock_name, sizeof(addr->sock_name), "scm_pidfd_%d", getpid());
+ addr->addrlen += strlen(addr->sock_name);
+ if (abstract) {
+ *sun_path_buf = '\0';
+ addr->addrlen++;
+ sun_path_buf++;
+ } else {
+ unlink(addr->sock_name);
+ }
+ memcpy(sun_path_buf, addr->sock_name, strlen(addr->sock_name));
+}
+
+static void client(FIXTURE_DATA(scm_pidfd) *self,
+ const FIXTURE_VARIANT(scm_pidfd) *variant)
+{
+ int err;
+ int cfd;
+ socklen_t len;
+ struct ucred peer_cred;
+ int peer_pidfd;
+ pid_t peer_pid;
+ int on = 0;
+
+ cfd = socket(AF_UNIX, variant->type, 0);
+ if (cfd < 0) {
+ log_err("socket");
+ child_die();
+ }
+
+ if (variant->type == SOCK_DGRAM) {
+ fill_sockaddr(self->client_addr, variant->abstract);
+
+ if (bind(cfd, (struct sockaddr *)&self->client_addr->listen_addr, self->client_addr->addrlen)) {
+ log_err("bind");
+ child_die();
+ }
+ }
+
+ if (connect(cfd, (struct sockaddr *)&self->server_addr.listen_addr,
+ self->server_addr.addrlen) != 0) {
+ log_err("connect");
+ child_die();
+ }
+
+ on = 1;
+ if (setsockopt(cfd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on))) {
+ log_err("Failed to set SO_PASSCRED");
+ child_die();
+ }
+
+ if (setsockopt(cfd, SOL_SOCKET, SO_PASSPIDFD, &on, sizeof(on))) {
+ log_err("Failed to set SO_PASSPIDFD");
+ child_die();
+ }
+
+ close(self->startup_pipe[1]);
+
+ if (cmsg_check(cfd)) {
+ log_err("cmsg_check failed");
+ child_die();
+ }
+
+ /* skip further for SOCK_DGRAM as it's not applicable */
+ if (variant->type == SOCK_DGRAM)
+ return;
+
+ len = sizeof(peer_cred);
+ if (getsockopt(cfd, SOL_SOCKET, SO_PEERCRED, &peer_cred, &len)) {
+ log_err("Failed to get SO_PEERCRED");
+ child_die();
+ }
+
+ len = sizeof(peer_pidfd);
+ if (getsockopt(cfd, SOL_SOCKET, SO_PEERPIDFD, &peer_pidfd, &len)) {
+ log_err("Failed to get SO_PEERPIDFD");
+ child_die();
+ }
+
+ /* pid from SO_PEERCRED should point to the parent process PID */
+ if (peer_cred.pid != getppid()) {
+ log_err("peer_cred.pid != getppid(): %d != %d", peer_cred.pid, getppid());
+ child_die();
+ }
+
+ peer_pid = get_pid_from_fdinfo_file(peer_pidfd,
+ "Pid:", sizeof("Pid:") - 1);
+ if (peer_pid != peer_cred.pid) {
+ log_err("peer_pid != peer_cred.pid: %d != %d", peer_pid, peer_cred.pid);
+ child_die();
+ }
+}
+
+TEST_F(scm_pidfd, test)
+{
+ int err;
+ int pfd;
+ int child_status = 0;
+
+ self->server = socket(AF_UNIX, variant->type, 0);
+ ASSERT_NE(-1, self->server);
+
+ fill_sockaddr(&self->server_addr, variant->abstract);
+
+ err = bind(self->server, (struct sockaddr *)&self->server_addr.listen_addr, self->server_addr.addrlen);
+ ASSERT_EQ(0, err);
+
+ if (variant->type == SOCK_STREAM) {
+ err = listen(self->server, 1);
+ ASSERT_EQ(0, err);
+ }
+
+ err = pipe(self->startup_pipe);
+ ASSERT_NE(-1, err);
+
+ self->client_pid = fork();
+ ASSERT_NE(-1, self->client_pid);
+ if (self->client_pid == 0) {
+ close(self->server);
+ close(self->startup_pipe[0]);
+ client(self, variant);
+ exit(0);
+ }
+ close(self->startup_pipe[1]);
+
+ if (variant->type == SOCK_STREAM) {
+ pfd = accept(self->server, NULL, NULL);
+ ASSERT_NE(-1, pfd);
+ } else {
+ pfd = self->server;
+ }
+
+ /* wait until the child arrives at checkpoint */
+ read(self->startup_pipe[0], &err, sizeof(int));
+ close(self->startup_pipe[0]);
+
+ if (variant->type == SOCK_DGRAM) {
+ err = sendto(pfd, "x", sizeof(char), 0, (struct sockaddr *)&self->client_addr->listen_addr, self->client_addr->addrlen);
+ ASSERT_NE(-1, err);
+ } else {
+ err = send(pfd, "x", sizeof(char), 0);
+ ASSERT_NE(-1, err);
+ }
+
+ close(pfd);
+ waitpid(self->client_pid, &child_status, 0);
+ ASSERT_EQ(0, WIFEXITED(child_status) ? WEXITSTATUS(child_status) : 1);
+}
+
+TEST_HARNESS_MAIN
Basic test to check consistency between: - SCM_CREDENTIALS and SCM_PIDFD - SO_PEERCRED and SO_PEERPIDFD Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: Leon Romanovsky <leon@kernel.org> Cc: David Ahern <dsahern@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Kees Cook <keescook@chromium.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Kuniyuki Iwashima <kuniyu@amazon.com> Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> --- v3: - started using kselftest lib (thanks to Kuniyuki Iwashima for suggestion/review) - now test covers abstract sockets too and SOCK_DGRAM sockets --- tools/testing/selftests/net/.gitignore | 1 + tools/testing/selftests/net/af_unix/Makefile | 3 +- .../testing/selftests/net/af_unix/scm_pidfd.c | 430 ++++++++++++++++++ 3 files changed, 433 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/net/af_unix/scm_pidfd.c