// 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