3 files changed, 299 insertions, 45 deletions

diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/selftests/net/af_unix/Makefile
index 50584479540b..a4b61c6d0290 100644
--- a/tools/testing/selftests/net/af_unix/Makefile
+++ b/tools/testing/selftests/net/af_unix/Makefile
@@ -1,4 +1,4 @@
 CFLAGS += $(KHDR_INCLUDES)
-TEST_GEN_PROGS := diag_uid msg_oob scm_pidfd scm_rights unix_connect
+TEST_GEN_PROGS := diag_uid msg_oob scm_inq scm_pidfd scm_rights unix_connect
 
 include ../../lib.mk
diff --git a/tools/testing/selftests/net/af_unix/scm_inq.c b/tools/testing/selftests/net/af_unix/scm_inq.c
new file mode 100644
index 000000000000..9d22561e7b8f
--- /dev/null
+++ b/tools/testing/selftests/net/af_unix/scm_inq.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2025 Google LLC */
+
+#include <linux/sockios.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include "../../kselftest_harness.h"
+
+#define NR_CHUNKS	100
+#define MSG_LEN		256
+
+struct scm_inq {
+	struct cmsghdr cmsghdr;
+	int inq;
+};
+
+FIXTURE(scm_inq)
+{
+	int fd[2];
+};
+
+FIXTURE_VARIANT(scm_inq)
+{
+	int type;
+};
+
+FIXTURE_VARIANT_ADD(scm_inq, stream)
+{
+	.type = SOCK_STREAM,
+};
+
+FIXTURE_VARIANT_ADD(scm_inq, dgram)
+{
+	.type = SOCK_DGRAM,
+};
+
+FIXTURE_VARIANT_ADD(scm_inq, seqpacket)
+{
+	.type = SOCK_SEQPACKET,
+};
+
+FIXTURE_SETUP(scm_inq)
+{
+	int err;
+
+	err = socketpair(AF_UNIX, variant->type | SOCK_NONBLOCK, 0, self->fd);
+	ASSERT_EQ(0, err);
+}
+
+FIXTURE_TEARDOWN(scm_inq)
+{
+	close(self->fd[0]);
+	close(self->fd[1]);
+}
+
+static void send_chunks(struct __test_metadata *_metadata,
+			FIXTURE_DATA(scm_inq) *self)
+{
+	char buf[MSG_LEN] = {};
+	int i, ret;
+
+	for (i = 0; i < NR_CHUNKS; i++) {
+		ret = send(self->fd[0], buf, sizeof(buf), 0);
+		ASSERT_EQ(sizeof(buf), ret);
+	}
+}
+
+static void recv_chunks(struct __test_metadata *_metadata,
+			FIXTURE_DATA(scm_inq) *self)
+{
+	struct msghdr msg = {};
+	struct iovec iov = {};
+	struct scm_inq cmsg;
+	char buf[MSG_LEN];
+	int i, ret;
+	int inq;
+
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	msg.msg_control = &cmsg;
+	msg.msg_controllen = CMSG_SPACE(sizeof(cmsg.inq));
+
+	iov.iov_base = buf;
+	iov.iov_len = sizeof(buf);
+
+	for (i = 0; i < NR_CHUNKS; i++) {
+		memset(buf, 0, sizeof(buf));
+		memset(&cmsg, 0, sizeof(cmsg));
+
+		ret = recvmsg(self->fd[1], &msg, 0);
+		ASSERT_EQ(MSG_LEN, ret);
+		ASSERT_NE(NULL, CMSG_FIRSTHDR(&msg));
+		ASSERT_EQ(CMSG_LEN(sizeof(cmsg.inq)), cmsg.cmsghdr.cmsg_len);
+		ASSERT_EQ(SOL_SOCKET, cmsg.cmsghdr.cmsg_level);
+		ASSERT_EQ(SCM_INQ, cmsg.cmsghdr.cmsg_type);
+
+		ret = ioctl(self->fd[1], SIOCINQ, &inq);
+		ASSERT_EQ(0, ret);
+		ASSERT_EQ(cmsg.inq, inq);
+	}
+}
+
+TEST_F(scm_inq, basic)
+{
+	int err, inq;
+
+	err = setsockopt(self->fd[1], SOL_SOCKET, SO_INQ, &(int){1}, sizeof(int));
+	if (variant->type != SOCK_STREAM) {
+		ASSERT_EQ(-ENOPROTOOPT, -errno);
+		return;
+	}
+
+	ASSERT_EQ(0, err);
+
+	err = ioctl(self->fd[1], SIOCINQ, &inq);
+	ASSERT_EQ(0, err);
+	ASSERT_EQ(0, inq);
+
+	send_chunks(_metadata, self);
+	recv_chunks(_metadata, self);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/net/af_unix/scm_pidfd.c b/tools/testing/selftests/net/af_unix/scm_pidfd.c
index 7e534594167e..37e034874034 100644
--- a/tools/testing/selftests/net/af_unix/scm_pidfd.c
+++ b/tools/testing/selftests/net/af_unix/scm_pidfd.c
@@ -15,6 +15,7 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 
+#include "../../pidfd/pidfd.h"
 #include "../../kselftest_harness.h"
 
 #define clean_errno() (errno == 0 ? "None" : strerror(errno))
@@ -26,6 +27,8 @@
 #define SCM_PIDFD 0x04
 #endif
 
+#define CHILD_EXIT_CODE_OK 123
+
 static void child_die()
 {
 	exit(1);
@@ -126,16 +129,65 @@ out:
 	return result;
 }
 
+struct cmsg_data {
+	struct ucred *ucred;
+	int *pidfd;
+};
+
+static int parse_cmsg(struct msghdr *msg, struct cmsg_data *res)
+{
+	struct cmsghdr *cmsg;
+	int data = 0;
+
+	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(*res->pidfd)) {
+				log_err("CMSG parse: SCM_PIDFD wrong len");
+				return 1;
+			}
+
+			res->pidfd = (void *)CMSG_DATA(cmsg);
+		}
+
+		if (cmsg->cmsg_level == SOL_SOCKET &&
+		    cmsg->cmsg_type == SCM_CREDENTIALS) {
+			if (cmsg->cmsg_len < sizeof(*res->ucred)) {
+				log_err("CMSG parse: SCM_CREDENTIALS wrong len");
+				return 1;
+			}
+
+			res->ucred = (void *)CMSG_DATA(cmsg);
+		}
+	}
+
+	if (!res->pidfd) {
+		log_err("CMSG parse: SCM_PIDFD not found");
+		return 1;
+	}
+
+	if (!res->ucred) {
+		log_err("CMSG parse: SCM_CREDENTIALS not found");
+		return 1;
+	}
+
+	return 0;
+}
+
 static int cmsg_check(int fd)
 {
 	struct msghdr msg = { 0 };
-	struct cmsghdr *cmsg;
+	struct cmsg_data res;
 	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;
 
@@ -158,53 +210,99 @@ static int cmsg_check(int fd)
 		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;
-			}
+	/* send(pfd, "x", sizeof(char), 0) */
+	if (data != 'x') {
+		log_err("recvmsg: data corruption");
+		return 1;
+	}
 
-			pidfd = (void *)CMSG_DATA(cmsg);
-		}
+	if (parse_cmsg(&msg, &res)) {
+		log_err("CMSG parse: parse_cmsg() failed");
+		return 1;
+	}
 
-		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;
-			}
+	/* pidfd from SCM_PIDFD should point to the parent process PID */
+	parent_pid =
+		get_pid_from_fdinfo_file(*res.pidfd, "Pid:", sizeof("Pid:") - 1);
+	if (parent_pid != getppid()) {
+		log_err("wrong SCM_PIDFD %d != %d", parent_pid, getppid());
+		close(*res.pidfd);
+		return 1;
+	}
 
-			ucred = (void *)CMSG_DATA(cmsg);
-		}
+	close(*res.pidfd);
+	return 0;
+}
+
+static int cmsg_check_dead(int fd, int expected_pid)
+{
+	int err;
+	struct msghdr msg = { 0 };
+	struct cmsg_data res;
+	struct iovec iov;
+	int data = 0;
+	char control[CMSG_SPACE(sizeof(struct ucred)) +
+		     CMSG_SPACE(sizeof(int))] = { 0 };
+	pid_t client_pid;
+	struct pidfd_info info = {
+		.mask = PIDFD_INFO_EXIT,
+	};
+
+	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;
 	}
 
-	/* send(pfd, "x", sizeof(char), 0) */
-	if (data != 'x') {
+	if (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC)) {
+		log_err("recvmsg: truncated");
+		return 1;
+	}
+
+	/* send(cfd, "y", sizeof(char), 0) */
+	if (data != 'y') {
 		log_err("recvmsg: data corruption");
 		return 1;
 	}
 
-	if (!pidfd) {
-		log_err("CMSG parse: SCM_PIDFD not found");
+	if (parse_cmsg(&msg, &res)) {
+		log_err("CMSG parse: parse_cmsg() failed");
 		return 1;
 	}
 
-	if (!ucred) {
-		log_err("CMSG parse: SCM_CREDENTIALS not found");
+	/*
+	 * pidfd from SCM_PIDFD should point to the client_pid.
+	 * Let's read exit information and check if it's what
+	 * we expect to see.
+	 */
+	if (ioctl(*res.pidfd, PIDFD_GET_INFO, &info)) {
+		log_err("%s: ioctl(PIDFD_GET_INFO) failed", __func__);
+		close(*res.pidfd);
 		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());
+	if (!(info.mask & PIDFD_INFO_EXIT)) {
+		log_err("%s: No exit information from ioctl(PIDFD_GET_INFO)", __func__);
+		close(*res.pidfd);
 		return 1;
 	}
 
+	err = WIFEXITED(info.exit_code) ? WEXITSTATUS(info.exit_code) : 1;
+	if (err != CHILD_EXIT_CODE_OK) {
+		log_err("%s: wrong exit_code %d != %d", __func__, err, CHILD_EXIT_CODE_OK);
+		close(*res.pidfd);
+		return 1;
+	}
+
+	close(*res.pidfd);
 	return 0;
 }
 
@@ -291,6 +389,24 @@ static void fill_sockaddr(struct sock_addr *addr, bool abstract)
 	memcpy(sun_path_buf, addr->sock_name, strlen(addr->sock_name));
 }
 
+static int sk_enable_cred_pass(int sk)
+{
+	int on = 0;
+
+	on = 1;
+	if (setsockopt(sk, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on))) {
+		log_err("Failed to set SO_PASSCRED");
+		return 1;
+	}
+
+	if (setsockopt(sk, SOL_SOCKET, SO_PASSPIDFD, &on, sizeof(on))) {
+		log_err("Failed to set SO_PASSPIDFD");
+		return 1;
+	}
+
+	return 0;
+}
+
 static void client(FIXTURE_DATA(scm_pidfd) *self,
 		   const FIXTURE_VARIANT(scm_pidfd) *variant)
 {
@@ -299,7 +415,6 @@ static void client(FIXTURE_DATA(scm_pidfd) *self,
 	struct ucred peer_cred;
 	int peer_pidfd;
 	pid_t peer_pid;
-	int on = 0;
 
 	cfd = socket(AF_UNIX, variant->type, 0);
 	if (cfd < 0) {
@@ -322,14 +437,8 @@ static void client(FIXTURE_DATA(scm_pidfd) *self,
 		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");
+	if (sk_enable_cred_pass(cfd)) {
+		log_err("sk_enable_cred_pass() failed");
 		child_die();
 	}
 
@@ -340,6 +449,12 @@ static void client(FIXTURE_DATA(scm_pidfd) *self,
 		child_die();
 	}
 
+	/* send something to the parent so it can receive SCM_PIDFD too and validate it */
+	if (send(cfd, "y", sizeof(char), 0) == -1) {
+		log_err("Failed to send(cfd, \"y\", sizeof(char), 0)");
+		child_die();
+	}
+
 	/* skip further for SOCK_DGRAM as it's not applicable */
 	if (variant->type == SOCK_DGRAM)
 		return;
@@ -398,7 +513,13 @@ TEST_F(scm_pidfd, test)
 		close(self->server);
 		close(self->startup_pipe[0]);
 		client(self, variant);
-		exit(0);
+
+		/*
+		 * It's a bit unusual, but in case of success we return non-zero
+		 * exit code (CHILD_EXIT_CODE_OK) and then we expect to read it
+		 * from ioctl(PIDFD_GET_INFO) in cmsg_check_dead().
+		 */
+		exit(CHILD_EXIT_CODE_OK);
 	}
 	close(self->startup_pipe[1]);
 
@@ -421,9 +542,17 @@ TEST_F(scm_pidfd, test)
 		ASSERT_NE(-1, err);
 	}
 
-	close(pfd);
 	waitpid(self->client_pid, &child_status, 0);
-	ASSERT_EQ(0, WIFEXITED(child_status) ? WEXITSTATUS(child_status) : 1);
+	/* see comment before exit(CHILD_EXIT_CODE_OK) */
+	ASSERT_EQ(CHILD_EXIT_CODE_OK, WIFEXITED(child_status) ? WEXITSTATUS(child_status) : 1);
+
+	err = sk_enable_cred_pass(pfd);
+	ASSERT_EQ(0, err);
+
+	err = cmsg_check_dead(pfd, self->client_pid);
+	ASSERT_EQ(0, err);
+
+	close(pfd);
 }
 
 TEST_HARNESS_MAIN