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selftests: net: extend SCM_PIDFD test to cover stale pidfds

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Extend SCM_PIDFD test scenarios to also cover dead task's
pidfd retrieval and reading its exit info.

Cc: linux-kselftest@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Shuah Khan <shuah@kernel.org>
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: Simon Horman <horms@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Kuniyuki Iwashima <kuniyu@google.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Luca Boccassi <bluca@debian.org>
Cc: David Rheinsberg <david@readahead.eu>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Link: https://lore.kernel.org/20250703222314.309967-8-aleksandr.mikhalitsyn@canonical.com
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Alexander Mikhalitsyn 2025-07-04 00:23:11 +02:00 committed by Christian Brauner
parent c679d17d3f
commit 861bdc6314
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 175 additions and 46 deletions
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221
tools/testing/selftests/net/af_unix/scm_pidfd.c
View File

@ -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 @@ static pid_t get_pid_from_fdinfo_file(int pidfd, const char *key, size_t keylen)
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;
}
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");
if (parse_cmsg(&msg, &res)) {
log_err("CMSG parse: parse_cmsg() failed");
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);
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;
}
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;
}
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 (parse_cmsg(&msg, &res)) {
log_err("CMSG parse: parse_cmsg() failed");
return 1;
}
/*
* 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;
}
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