Basic test to check consistency between:
- SCM_CREDENTIALS and SCM_PIDFD
- SO_PEERCRED and SO_PEERPIDFD
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Leon Romanovsky <leon@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-kselftest@xxxxxxxxxxxxxxx
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
---
tools/testing/selftests/net/.gitignore | 1 +
tools/testing/selftests/net/af_unix/Makefile | 3 +-
.../testing/selftests/net/af_unix/scm_pidfd.c | 336 ++++++++++++++++++
3 files changed, 339 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/net/af_unix/scm_pidfd.c
diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
index a6911cae368c..f2d23a1df596 100644
--- a/tools/testing/selftests/net/.gitignore
+++ b/tools/testing/selftests/net/.gitignore
@@ -25,6 +25,7 @@ reuseport_bpf_cpu
reuseport_bpf_numa
reuseport_dualstack
rxtimestamp
+scm_pidfd
sk_bind_sendto_listen
sk_connect_zero_addr
socket
diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
index 1e4b397cece6..221c387a7d7f 100644
--- a/tools/testing/selftests/net/af_unix/Makefile
+++ b/tools/testing/selftests/net/af_unix/Makefile
@@ -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
diff --git a/tools/testing/selftests/net/af_unix/scm_pidfd.c b/tools/testing/selftests/net/af_unix/scm_pidfd.c
new file mode 100644
index 000000000000..fa502510ee9e
--- /dev/null
+++ b/tools/testing/selftests/net/af_unix/scm_pidfd.c
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <error.h>
+#include <limits.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>
+
+#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 pid_t client_pid;
+static char sock_name[32];
+
+static void die(int status)
+{
+ unlink(sock_name);
+ kill(client_pid, SIGTERM);
+ exit(status);
+}
+
+static void child_die()
+{
+ kill(getppid(), SIGTERM);
+ 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;
+}
+
+void client(struct sockaddr_un *listen_addr)
+{
+ int cfd;
+ socklen_t len;
+ struct ucred peer_cred;
+ int peer_pidfd;
+ pid_t peer_pid;
+ int on = 0;
+
+ cfd = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (cfd < 0) {
+ log_err("socket");
+ child_die();
+ }
+
+ if (connect(cfd, (struct sockaddr *)listen_addr,
+ sizeof(*listen_addr)) != 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();
+ }
+
+ if (cmsg_check(cfd)) {
+ log_err("cmsg_check failed");
+ child_die();
+ }
+
+ 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("Failed to get SO_PEERPIDFD");
+ child_die();
+ }
+
+ peer_pid = get_pid_from_fdinfo_file(peer_pidfd,
+ "Pid:", sizeof("Pid:") - 1);
+ if (peer_pid != peer_cred.pid) {
+ log_err("Failed to get SO_PEERPIDFD");
+ child_die();
+ }
+}
+
+int main(int argc, char **argv)
+{
+ int lfd, pfd;
+ int child_status = 0;
+ struct sockaddr_un listen_addr;
+
+ lfd = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (lfd < 0) {
+ perror("socket");
+ exit(1);
+ }
+
+ memset(&listen_addr, 0, sizeof(listen_addr));
+ listen_addr.sun_family = AF_UNIX;
+ sprintf(sock_name, "scm_pidfd_%d", getpid());
+ unlink(sock_name);
+ strcpy(listen_addr.sun_path, sock_name);
+
+ if ((bind(lfd, (struct sockaddr *)&listen_addr, sizeof(listen_addr))) !=
+ 0) {
+ perror("socket bind failed");
+ exit(1);
+ }
+
+ if (listen(lfd, 1) < 0) {
+ perror("listen");
+ exit(1);
+ }
+
+ client_pid = fork();
+ if (client_pid < 0) {
+ perror("fork");
+ exit(1);
+ }
+
+ if (client_pid == 0) {
+ client(&listen_addr);
+ exit(0);
+ }
+
+ pfd = accept(lfd, NULL, NULL);
+ if (pfd < 0) {
+ perror("accept");
+ die(1);
+ }
+
+ if (send(pfd, "x", sizeof(char), 0) < 0) {
+ perror("send");
+ die(1);
+ }
+
+ waitpid(client_pid, &child_status, 0);
+ die(WIFEXITED(child_status) ? WEXITSTATUS(child_status) : 1);
+ die(0);
+}
\ No newline at end of file
--
2.34.1
