// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <linux/netlink.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/socket.h>
#include <sched.h>
#include <sys/eventfd.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include "../kselftest_harness.h"
#define __DEV_FULL "/sys/devices/virtual/mem/full/uevent"
#define __UEVENT_BUFFER_SIZE (2048 * 2)
#define __UEVENT_HEADER "add@/devices/virtual/mem/full"
#define __UEVENT_HEADER_LEN sizeof("add@/devices/virtual/mem/full")
#define __UEVENT_LISTEN_ALL -1
ssize_t read_nointr(int fd, void *buf, size_t count)
{
ssize_t ret;
again:
ret = read(fd, buf, count);
if (ret < 0 && errno == EINTR)
goto again;
return ret;
}
ssize_t write_nointr(int fd, const void *buf, size_t count)
{
ssize_t ret;
again:
ret = write(fd, buf, count);
if (ret < 0 && errno == EINTR)
goto again;
return ret;
}
int wait_for_pid(pid_t pid)
{
int status, ret;
again:
ret = waitpid(pid, &status, 0);
if (ret == -1) {
if (errno == EINTR)
goto again;
return -1;
}
if (ret != pid)
goto again;
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
return -1;
return 0;
}
static int uevent_listener(unsigned long post_flags, bool expect_uevent,
int sync_fd)
{
int sk_fd, ret;
socklen_t sk_addr_len;
int rcv_buf_sz = __UEVENT_BUFFER_SIZE;
uint64_t sync_add = 1;
struct sockaddr_nl sk_addr = { 0 }, rcv_addr = { 0 };
char buf[__UEVENT_BUFFER_SIZE] = { 0 };
struct iovec iov = { buf, __UEVENT_BUFFER_SIZE };
char control[CMSG_SPACE(sizeof(struct ucred))];
struct msghdr hdr = {
&rcv_addr, sizeof(rcv_addr), &iov, 1,
control, sizeof(control), 0,
};
sk_fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC,
NETLINK_KOBJECT_UEVENT);
if (sk_fd < 0) {
fprintf(stderr, "%s - Failed to open uevent socket\n", strerror(errno));
return -1;
}
ret = setsockopt(sk_fd, SOL_SOCKET, SO_RCVBUF, &rcv_buf_sz,
sizeof(rcv_buf_sz));
if (ret < 0) {
fprintf(stderr, "%s - Failed to set socket options\n", strerror(errno));
goto on_error;
}
sk_addr.nl_family = AF_NETLINK;
sk_addr.nl_groups = __UEVENT_LISTEN_ALL;
sk_addr_len = sizeof(sk_addr);
ret = bind(sk_fd, (struct sockaddr *)&sk_addr, sk_addr_len);
if (ret < 0) {
fprintf(stderr, "%s - Failed to bind socket\n", strerror(errno));
goto on_error;
}
ret = getsockname(sk_fd, (struct sockaddr *)&sk_addr, &sk_addr_len);
if (ret < 0) {
fprintf(stderr, "%s - Failed to retrieve socket name\n", strerror(errno));
goto on_error;
}
if ((size_t)sk_addr_len != sizeof(sk_addr)) {
fprintf(stderr, "Invalid socket address size\n");
ret = -1;
goto on_error;
}
if (post_flags & CLONE_NEWUSER) {
ret = unshare(CLONE_NEWUSER);
if (ret < 0) {
fprintf(stderr,
"%s - Failed to unshare user namespace\n",
strerror(errno));
goto on_error;
}
}
if (post_flags & CLONE_NEWNET) {
ret = unshare(CLONE_NEWNET);
if (ret < 0) {
fprintf(stderr,
"%s - Failed to unshare network namespace\n",
strerror(errno));
goto on_error;
}
}
ret = write_nointr(sync_fd, &sync_add, sizeof(sync_add));
close(sync_fd);
if (ret != sizeof(sync_add)) {
ret = -1;
fprintf(stderr, "Failed to synchronize with parent process\n");
goto on_error;
}
ret = 0;
for (;;) {
ssize_t r;
r = recvmsg(sk_fd, &hdr, 0);
if (r <= 0) {
fprintf(stderr, "%s - Failed to receive uevent\n", strerror(errno));
ret = -1;
break;
}
/* ignore libudev messages */
if (memcmp(buf, "libudev", 8) == 0)
continue;
/* ignore uevents we didn't trigger */
if (memcmp(buf, __UEVENT_HEADER, __UEVENT_HEADER_LEN) != 0)
continue;
if (!expect_uevent) {
fprintf(stderr, "Received unexpected uevent:\n");
ret = -1;
}
if (TH_LOG_ENABLED) {
/* If logging is enabled dump the received uevent. */
(void)write_nointr(STDERR_FILENO, buf, r);
(void)write_nointr(STDERR_FILENO, "\n", 1);
}
break;
}
on_error:
close(sk_fd);
return ret;
}
int trigger_uevent(unsigned int times)
{
int fd, ret;
unsigned int i;
fd = open(__DEV_FULL, O_RDWR | O_CLOEXEC);
if (fd < 0) {
if (errno != ENOENT)
return -EINVAL;
return -1;
}
for (i = 0; i < times; i++) {
ret = write_nointr(fd, "add\n", sizeof("add\n") - 1);
if (ret < 0) {
fprintf(stderr, "Failed to trigger uevent\n");
break;
}
}
close(fd);
return ret;
}
int set_death_signal(void)
{
int ret;
pid_t ppid;
ret = prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
/* Check whether we have been orphaned. */
ppid = getppid();
if (ppid == 1) {
pid_t self;
self = getpid();
ret = kill(self, SIGKILL);
}
if (ret < 0)
return -1;
return 0;
}
static int do_test(unsigned long pre_flags, unsigned long post_flags,
bool expect_uevent, int sync_fd)
{
int ret;
uint64_t wait_val;
pid_t pid;
sigset_t mask;
sigset_t orig_mask;
struct timespec timeout;
sigemptyset(&mask);
sigaddset(&mask, SIGCHLD);
ret = sigprocmask(SIG_BLOCK, &mask, &orig_mask);
if (ret < 0) {
fprintf(stderr, "%s- Failed to block SIGCHLD\n", strerror(errno));
return -1;
}
pid = fork();
if (pid < 0) {
fprintf(stderr, "%s - Failed to fork() new process\n", strerror(errno));
return -1;
}
if (pid == 0) {
/* Make sure that we go away when our parent dies. */
ret = set_death_signal();
if (ret < 0) {
fprintf(stderr, "Failed to set PR_SET_PDEATHSIG to SIGKILL\n");
_exit(EXIT_FAILURE);
}
if (pre_flags & CLONE_NEWUSER) {
ret = unshare(CLONE_NEWUSER);
if (ret < 0) {
fprintf(stderr,
"%s - Failed to unshare user namespace\n",
strerror(errno));
_exit(EXIT_FAILURE);
}
}
if (pre_flags & CLONE_NEWNET) {
ret = unshare(CLONE_NEWNET);
if (ret < 0) {
fprintf(stderr,
"%s - Failed to unshare network namespace\n",
strerror(errno));
_exit(EXIT_FAILURE);
}
}
if (uevent_listener(post_flags, expect_uevent, sync_fd) < 0)
_exit(EXIT_FAILURE);
_exit(EXIT_SUCCESS);
}
ret = read_nointr(sync_fd, &wait_val, sizeof(wait_val));
if (ret != sizeof(wait_val)) {
fprintf(stderr, "Failed to synchronize with child process\n");
_exit(EXIT_FAILURE);
}
/* Trigger 10 uevents to account for the case where the kernel might
* drop some.
*/
ret = trigger_uevent(10);
if (ret < 0)
fprintf(stderr, "Failed triggering uevents\n");
/* Wait for 2 seconds before considering this failed. This should be
* plenty of time for the kernel to deliver the uevent even under heavy
* load.
*/
timeout.tv_sec = 2;
timeout.tv_nsec = 0;
again:
ret = sigtimedwait(&mask, NULL, &timeout);
if (ret < 0) {
if (errno == EINTR)
goto again;
if (!expect_uevent)
ret = kill(pid, SIGTERM); /* success */
else
ret = kill(pid, SIGUSR1); /* error */
if (ret < 0)
return -1;
}
ret = wait_for_pid(pid);
if (ret < 0)
return -1;
return ret;
}
static void signal_handler(int sig)
{
if (sig == SIGTERM)
_exit(EXIT_SUCCESS);
_exit(EXIT_FAILURE);
}
TEST(uevent_filtering)
{
int ret, sync_fd;
struct sigaction act;
if (geteuid()) {
TH_LOG("Uevent filtering tests require root privileges. Skipping test");
_exit(KSFT_SKIP);
}
ret = access(__DEV_FULL, F_OK);
EXPECT_EQ(0, ret) {
if (errno == ENOENT) {
TH_LOG(__DEV_FULL " does not exist. Skipping test");
_exit(KSFT_SKIP);
}
_exit(KSFT_FAIL);
}
act.sa_handler = signal_handler;
act.sa_flags = 0;
sigemptyset(&act.sa_mask);
ret = sigaction(SIGTERM, &act, NULL);
ASSERT_EQ(0, ret);
sync_fd = eventfd(0, EFD_CLOEXEC);
ASSERT_GE(sync_fd, 0);
/*
* Setup:
* - Open uevent listening socket in initial network namespace owned by
* initial user namespace.
* - Trigger uevent in initial network namespace owned by initial user
* namespace.
* Expected Result:
* - uevent listening socket receives uevent
*/
ret = do_test(0, 0, true, sync_fd);
ASSERT_EQ(0, ret) {
goto do_cleanup;
}
/*
* Setup:
* - Open uevent listening socket in non-initial network namespace
* owned by initial user namespace.
* - Trigger uevent in initial network namespace owned by initial user
* namespace.
* Expected Result:
* - uevent listening socket receives uevent
*/
ret = do_test(CLONE_NEWNET, 0, true, sync_fd);
ASSERT_EQ(0, ret) {
goto do_cleanup;
}
/*
* Setup:
* - unshare user namespace
* - Open uevent listening socket in initial network namespace
* owned by initial user namespace.
* - Trigger uevent in initial network namespace owned by initial user
* namespace.
* Expected Result:
* - uevent listening socket receives uevent
*/
ret = do_test(CLONE_NEWUSER, 0, true, sync_fd);
ASSERT_EQ(0, ret) {
goto do_cleanup;
}
/*
* Setup:
* - Open uevent listening socket in non-initial network namespace
* owned by non-initial user namespace.
* - Trigger uevent in initial network namespace owned by initial user
* namespace.
* Expected Result:
* - uevent listening socket receives no uevent
*/
ret = do_test(CLONE_NEWUSER | CLONE_NEWNET, 0, false, sync_fd);
ASSERT_EQ(0, ret) {
goto do_cleanup;
}
/*
* Setup:
* - Open uevent listening socket in initial network namespace
* owned by initial user namespace.
* - unshare network namespace
* - Trigger uevent in initial network namespace owned by initial user
* namespace.
* Expected Result:
* - uevent listening socket receives uevent
*/
ret = do_test(0, CLONE_NEWNET, true, sync_fd);
ASSERT_EQ(0, ret) {
goto do_cleanup;
}
/*
* Setup:
* - Open uevent listening socket in initial network namespace
* owned by initial user namespace.
* - unshare user namespace
* - Trigger uevent in initial network namespace owned by initial user
* namespace.
* Expected Result:
* - uevent listening socket receives uevent
*/
ret = do_test(0, CLONE_NEWUSER, true, sync_fd);
ASSERT_EQ(0, ret) {
goto do_cleanup;
}
/*
* Setup:
* - Open uevent listening socket in initial network namespace
* owned by initial user namespace.
* - unshare user namespace
* - unshare network namespace
* - Trigger uevent in initial network namespace owned by initial user
* namespace.
* Expected Result:
* - uevent listening socket receives uevent
*/
ret = do_test(0, CLONE_NEWUSER | CLONE_NEWNET, true, sync_fd);
ASSERT_EQ(0, ret) {
goto do_cleanup;
}
do_cleanup:
close(sync_fd);
}
TEST_HARNESS_MAIN
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