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Diffstat (limited to 'src/weston-launch.c')
| -rw-r--r-- | src/weston-launch.c | 750 |
1 files changed, 750 insertions, 0 deletions
diff --git a/src/weston-launch.c b/src/weston-launch.c new file mode 100644 index 00000000..d8364c85 --- /dev/null +++ b/src/weston-launch.c @@ -0,0 +1,750 @@ +/* + * Copyright © 2012 Benjamin Franzke + * + * Permission to use, copy, modify, distribute, and sell this software and + * its documentation for any purpose is hereby granted without fee, provided + * that the above copyright notice appear in all copies and that both that + * copyright notice and this permission notice appear in supporting + * documentation, and that the name of the copyright holders not be used in + * advertising or publicity pertaining to distribution of the software + * without specific, written prior permission. The copyright holders make + * no representations about the suitability of this software for any + * purpose. It is provided "as is" without express or implied warranty. + * + * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS + * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND + * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY + * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER + * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF + * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include "config.h" + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <assert.h> +#include <poll.h> +#include <errno.h> + +#include <error.h> +#include <getopt.h> + +#include <sys/types.h> +#include <sys/ioctl.h> +#include <sys/stat.h> +#include <sys/wait.h> +#include <sys/socket.h> +#include <sys/signalfd.h> +#include <signal.h> +#include <unistd.h> +#include <fcntl.h> + +#include <linux/vt.h> +#include <linux/major.h> +#include <linux/kd.h> + +#include <pwd.h> +#include <grp.h> +#include <security/pam_appl.h> + +#include <xf86drm.h> + +#ifdef HAVE_SYSTEMD_LOGIN +#include <systemd/sd-login.h> +#endif + +#include "weston-launch.h" + +#define DRM_MAJOR 226 + +#ifndef KDSKBMUTE +#define KDSKBMUTE 0x4B51 +#endif + +#ifndef EVIOCREVOKE +#define EVIOCREVOKE _IOW('E', 0x91, int) +#endif + +#define MAX_ARGV_SIZE 256 + +struct weston_launch { + struct pam_conv pc; + pam_handle_t *ph; + int tty; + int ttynr; + int sock[2]; + int drm_fd; + int last_input_fd; + int kb_mode; + struct passwd *pw; + + int signalfd; + + pid_t child; + int verbose; + char *new_user; +}; + +union cmsg_data { unsigned char b[4]; int fd; }; + +static gid_t * +read_groups(void) +{ + int n; + gid_t *groups; + + n = getgroups(0, NULL); + + if (n < 0) { + fprintf(stderr, "Unable to retrieve groups: %m\n"); + return NULL; + } + + groups = malloc(n * sizeof(gid_t)); + if (!groups) + return NULL; + + if (getgroups(n, groups) < 0) { + fprintf(stderr, "Unable to retrieve groups: %m\n"); + free(groups); + return NULL; + } + return groups; +} + +static int +weston_launch_allowed(struct weston_launch *wl) +{ + struct group *gr; + gid_t *groups; + int i; +#ifdef HAVE_SYSTEMD_LOGIN + char *session, *seat; + int err; +#endif + + if (getuid() == 0) + return 1; + + gr = getgrnam("weston-launch"); + if (gr) { + groups = read_groups(); + if (groups) { + for (i = 0; groups[i]; ++i) { + if (groups[i] == gr->gr_gid) { + free(groups); + return 1; + } + } + free(groups); + } + } + +#ifdef HAVE_SYSTEMD_LOGIN + err = sd_pid_get_session(getpid(), &session); + if (err == 0 && session) { + if (sd_session_is_active(session) && + sd_session_get_seat(session, &seat) == 0) { + free(seat); + free(session); + return 1; + } + free(session); + } +#endif + + return 0; +} + +static int +pam_conversation_fn(int msg_count, + const struct pam_message **messages, + struct pam_response **responses, + void *user_data) +{ + return PAM_SUCCESS; +} + +static int +setup_pam(struct weston_launch *wl) +{ + int err; + + wl->pc.conv = pam_conversation_fn; + wl->pc.appdata_ptr = wl; + + err = pam_start("login", wl->pw->pw_name, &wl->pc, &wl->ph); + if (err != PAM_SUCCESS) { + fprintf(stderr, "failed to start pam transaction: %d: %s\n", + err, pam_strerror(wl->ph, err)); + return -1; + } + + err = pam_set_item(wl->ph, PAM_TTY, ttyname(wl->tty)); + if (err != PAM_SUCCESS) { + fprintf(stderr, "failed to set PAM_TTY item: %d: %s\n", + err, pam_strerror(wl->ph, err)); + return -1; + } + + err = pam_open_session(wl->ph, 0); + if (err != PAM_SUCCESS) { + fprintf(stderr, "failed to open pam session: %d: %s\n", + err, pam_strerror(wl->ph, err)); + return -1; + } + + return 0; +} + +static int +setup_launcher_socket(struct weston_launch *wl) +{ + if (socketpair(AF_LOCAL, SOCK_SEQPACKET, 0, wl->sock) < 0) + error(1, errno, "socketpair failed"); + + if (fcntl(wl->sock[0], F_SETFD, FD_CLOEXEC) < 0) + error(1, errno, "fcntl failed"); + + return 0; +} + +static int +setup_signals(struct weston_launch *wl) +{ + int ret; + sigset_t mask; + struct sigaction sa; + + memset(&sa, 0, sizeof sa); + sa.sa_handler = SIG_DFL; + sa.sa_flags = SA_NOCLDSTOP | SA_RESTART; + ret = sigaction(SIGCHLD, &sa, NULL); + assert(ret == 0); + + sa.sa_handler = SIG_IGN; + sa.sa_flags = 0; + sigaction(SIGHUP, &sa, NULL); + + ret = sigemptyset(&mask); + assert(ret == 0); + sigaddset(&mask, SIGCHLD); + sigaddset(&mask, SIGINT); + sigaddset(&mask, SIGTERM); + sigaddset(&mask, SIGUSR1); + sigaddset(&mask, SIGUSR2); + ret = sigprocmask(SIG_BLOCK, &mask, NULL); + assert(ret == 0); + + wl->signalfd = signalfd(-1, &mask, SFD_NONBLOCK | SFD_CLOEXEC); + if (wl->signalfd < 0) + return -errno; + + return 0; +} + +static void +setenv_fd(const char *env, int fd) +{ + char buf[32]; + + snprintf(buf, sizeof buf, "%d", fd); + setenv(env, buf, 1); +} + +static int +send_reply(struct weston_launch *wl, int reply) +{ + int len; + + do { + len = send(wl->sock[0], &reply, sizeof reply, 0); + } while (len < 0 && errno == EINTR); + + return len; +} + +static int +handle_open(struct weston_launch *wl, struct msghdr *msg, ssize_t len) +{ + int fd = -1, ret = -1; + char control[CMSG_SPACE(sizeof(fd))]; + struct cmsghdr *cmsg; + struct stat s; + struct msghdr nmsg; + struct iovec iov; + struct weston_launcher_open *message; + union cmsg_data *data; + + message = msg->msg_iov->iov_base; + if ((size_t)len < sizeof(*message)) + goto err0; + + /* Ensure path is null-terminated */ + ((char *) message)[len-1] = '\0'; + + fd = open(message->path, message->flags); + if (fd < 0) { + fprintf(stderr, "Error opening device %s: %m\n", + message->path); + goto err0; + } + + if (fstat(fd, &s) < 0) { + close(fd); + fd = -1; + fprintf(stderr, "Failed to stat %s\n", message->path); + goto err0; + } + + if (major(s.st_rdev) != INPUT_MAJOR && + major(s.st_rdev) != DRM_MAJOR) { + close(fd); + fd = -1; + fprintf(stderr, "Device %s is not an input or drm device\n", + message->path); + goto err0; + } + +err0: + memset(&nmsg, 0, sizeof nmsg); + nmsg.msg_iov = &iov; + nmsg.msg_iovlen = 1; + if (fd != -1) { + nmsg.msg_control = control; + nmsg.msg_controllen = sizeof control; + cmsg = CMSG_FIRSTHDR(&nmsg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(fd)); + data = (union cmsg_data *) CMSG_DATA(cmsg); + data->fd = fd; + nmsg.msg_controllen = cmsg->cmsg_len; + ret = 0; + } + iov.iov_base = &ret; + iov.iov_len = sizeof ret; + + if (wl->verbose) + fprintf(stderr, "weston-launch: opened %s: ret: %d, fd: %d\n", + message->path, ret, fd); + do { + len = sendmsg(wl->sock[0], &nmsg, 0); + } while (len < 0 && errno == EINTR); + + if (len < 0) + return -1; + + if (fd != -1 && major(s.st_rdev) == DRM_MAJOR) + wl->drm_fd = fd; + if (fd != -1 && major(s.st_rdev) == INPUT_MAJOR && + wl->last_input_fd < fd) + wl->last_input_fd = fd; + + return 0; +} + +static int +handle_socket_msg(struct weston_launch *wl) +{ + char control[CMSG_SPACE(sizeof(int))]; + char buf[BUFSIZ]; + struct msghdr msg; + struct iovec iov; + int ret = -1; + ssize_t len; + struct weston_launcher_message *message; + + memset(&msg, 0, sizeof(msg)); + iov.iov_base = buf; + iov.iov_len = sizeof buf; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = control; + msg.msg_controllen = sizeof control; + + do { + len = recvmsg(wl->sock[0], &msg, 0); + } while (len < 0 && errno == EINTR); + + if (len < 1) + return -1; + + message = (void *) buf; + switch (message->opcode) { + case WESTON_LAUNCHER_OPEN: + ret = handle_open(wl, &msg, len); + break; + } + + return ret; +} + +static void +quit(struct weston_launch *wl, int status) +{ + struct vt_mode mode = { 0 }; + int err; + + close(wl->signalfd); + close(wl->sock[0]); + + if (wl->new_user) { + err = pam_close_session(wl->ph, 0); + if (err) + fprintf(stderr, "pam_close_session failed: %d: %s\n", + err, pam_strerror(wl->ph, err)); + pam_end(wl->ph, err); + } + + if (ioctl(wl->tty, KDSKBMUTE, 0) && + ioctl(wl->tty, KDSKBMODE, wl->kb_mode)) + fprintf(stderr, "failed to restore keyboard mode: %m\n"); + + if (ioctl(wl->tty, KDSETMODE, KD_TEXT)) + fprintf(stderr, "failed to set KD_TEXT mode on tty: %m\n"); + + /* We have to drop master before we switch the VT back in + * VT_AUTO, so we don't risk switching to a VT with another + * display server, that will then fail to set drm master. */ + drmDropMaster(wl->drm_fd); + + mode.mode = VT_AUTO; + if (ioctl(wl->tty, VT_SETMODE, &mode) < 0) + fprintf(stderr, "could not reset vt handling\n"); + + exit(status); +} + +static void +close_input_fds(struct weston_launch *wl) +{ + struct stat s; + int fd; + + for (fd = 3; fd <= wl->last_input_fd; fd++) { + if (fstat(fd, &s) == 0 && major(s.st_rdev) == INPUT_MAJOR) { + /* EVIOCREVOKE may fail if the kernel doesn't + * support it, but all we can do is ignore it. */ + ioctl(fd, EVIOCREVOKE, 0); + close(fd); + } + } +} + +static int +handle_signal(struct weston_launch *wl) +{ + struct signalfd_siginfo sig; + int pid, status, ret; + + if (read(wl->signalfd, &sig, sizeof sig) != sizeof sig) { + error(0, errno, "reading signalfd failed"); + return -1; + } + + switch (sig.ssi_signo) { + case SIGCHLD: + pid = waitpid(-1, &status, 0); + if (pid == wl->child) { + wl->child = 0; + if (WIFEXITED(status)) + ret = WEXITSTATUS(status); + else if (WIFSIGNALED(status)) + /* + * If weston dies because of signal N, we + * return 10+N. This is distinct from + * weston-launch dying because of a signal + * (128+N). + */ + ret = 10 + WTERMSIG(status); + else + ret = 0; + quit(wl, ret); + } + break; + case SIGTERM: + case SIGINT: + if (wl->child) + kill(wl->child, sig.ssi_signo); + break; + case SIGUSR1: + send_reply(wl, WESTON_LAUNCHER_DEACTIVATE); + close_input_fds(wl); + drmDropMaster(wl->drm_fd); + ioctl(wl->tty, VT_RELDISP, 1); + break; + case SIGUSR2: + ioctl(wl->tty, VT_RELDISP, VT_ACKACQ); + drmSetMaster(wl->drm_fd); + send_reply(wl, WESTON_LAUNCHER_ACTIVATE); + break; + default: + return -1; + } + + return 0; +} + +static int +setup_tty(struct weston_launch *wl, const char *tty) +{ + struct stat buf; + struct vt_mode mode = { 0 }; + char *t; + + if (!wl->new_user) { + wl->tty = STDIN_FILENO; + } else if (tty) { + t = ttyname(STDIN_FILENO); + if (t && strcmp(t, tty) == 0) + wl->tty = STDIN_FILENO; + else + wl->tty = open(tty, O_RDWR | O_NOCTTY); + } else { + int tty0 = open("/dev/tty0", O_WRONLY | O_CLOEXEC); + char filename[16]; + + if (tty0 < 0) + error(1, errno, "could not open tty0"); + + if (ioctl(tty0, VT_OPENQRY, &wl->ttynr) < 0 || wl->ttynr == -1) + error(1, errno, "failed to find non-opened console"); + + snprintf(filename, sizeof filename, "/dev/tty%d", wl->ttynr); + wl->tty = open(filename, O_RDWR | O_NOCTTY); + close(tty0); + } + + if (wl->tty < 0) + error(1, errno, "failed to open tty"); + + if (fstat(wl->tty, &buf) == -1 || + major(buf.st_rdev) != TTY_MAJOR || minor(buf.st_rdev) == 0) + error(1, 0, "weston-launch must be run from a virtual terminal"); + + if (tty) { + if (fstat(wl->tty, &buf) < 0) + error(1, errno, "stat %s failed", tty); + + if (major(buf.st_rdev) != TTY_MAJOR) + error(1, 0, "invalid tty device: %s", tty); + + wl->ttynr = minor(buf.st_rdev); + } + + if (ioctl(wl->tty, KDGKBMODE, &wl->kb_mode)) + error(1, errno, "failed to get current keyboard mode: %m\n"); + + if (ioctl(wl->tty, KDSKBMUTE, 1) && + ioctl(wl->tty, KDSKBMODE, K_OFF)) + error(1, errno, "failed to set K_OFF keyboard mode: %m\n"); + + if (ioctl(wl->tty, KDSETMODE, KD_GRAPHICS)) + error(1, errno, "failed to set KD_GRAPHICS mode on tty: %m\n"); + + mode.mode = VT_PROCESS; + mode.relsig = SIGUSR1; + mode.acqsig = SIGUSR2; + if (ioctl(wl->tty, VT_SETMODE, &mode) < 0) + error(1, errno, "failed to take control of vt handling\n"); + + return 0; +} + +static void +setup_session(struct weston_launch *wl) +{ + char **env; + char *term; + int i; + + if (wl->tty != STDIN_FILENO) { + if (setsid() < 0) + error(1, errno, "setsid failed"); + if (ioctl(wl->tty, TIOCSCTTY, 0) < 0) + error(1, errno, "TIOCSCTTY failed - tty is in use"); + } + + term = getenv("TERM"); + clearenv(); + if (term) + setenv("TERM", term, 1); + setenv("USER", wl->pw->pw_name, 1); + setenv("LOGNAME", wl->pw->pw_name, 1); + setenv("HOME", wl->pw->pw_dir, 1); + setenv("SHELL", wl->pw->pw_shell, 1); + + env = pam_getenvlist(wl->ph); + if (env) { + for (i = 0; env[i]; ++i) { + if (putenv(env[i]) < 0) + error(0, 0, "putenv %s failed", env[i]); + } + free(env); + } +} + +static void +drop_privileges(struct weston_launch *wl) +{ + if (setgid(wl->pw->pw_gid) < 0 || +#ifdef HAVE_INITGROUPS + initgroups(wl->pw->pw_name, wl->pw->pw_gid) < 0 || +#endif + setuid(wl->pw->pw_uid) < 0) + error(1, errno, "dropping privileges failed"); +} + +static void +launch_compositor(struct weston_launch *wl, int argc, char *argv[]) +{ + char *child_argv[MAX_ARGV_SIZE]; + sigset_t mask; + int i; + + if (wl->verbose) + printf("weston-launch: spawned weston with pid: %d\n", getpid()); + if (wl->new_user) + setup_session(wl); + + if (geteuid() == 0) + drop_privileges(wl); + + setenv_fd("WESTON_TTY_FD", wl->tty); + setenv_fd("WESTON_LAUNCHER_SOCK", wl->sock[1]); + + unsetenv("DISPLAY"); + + /* Do not give our signal mask to the new process. */ + sigemptyset(&mask); + sigaddset(&mask, SIGTERM); + sigaddset(&mask, SIGCHLD); + sigaddset(&mask, SIGINT); + sigprocmask(SIG_UNBLOCK, &mask, NULL); + + child_argv[0] = "/bin/sh"; + child_argv[1] = "-l"; + child_argv[2] = "-c"; + child_argv[3] = BINDIR "/weston \"$@\""; + child_argv[4] = "weston"; + for (i = 0; i < argc; ++i) + child_argv[5 + i] = argv[i]; + child_argv[5 + i] = NULL; + + execv(child_argv[0], child_argv); + error(1, errno, "exec failed"); +} + +static void +help(const char *name) +{ + fprintf(stderr, "Usage: %s [args...] [-- [weston args..]]\n", name); + fprintf(stderr, " -u, --user Start session as specified username\n"); + fprintf(stderr, " -t, --tty Start session on alternative tty\n"); + fprintf(stderr, " -v, --verbose Be verbose\n"); + fprintf(stderr, " -h, --help Display this help message\n"); +} + +int +main(int argc, char *argv[]) +{ + struct weston_launch wl; + int i, c; + char *tty = NULL; + struct option opts[] = { + { "user", required_argument, NULL, 'u' }, + { "tty", required_argument, NULL, 't' }, + { "verbose", no_argument, NULL, 'v' }, + { "help", no_argument, NULL, 'h' }, + { 0, 0, NULL, 0 } + }; + + memset(&wl, 0, sizeof wl); + + while ((c = getopt_long(argc, argv, "u:t::vh", opts, &i)) != -1) { + switch (c) { + case 'u': + wl.new_user = optarg; + if (getuid() != 0) + error(1, 0, "Permission denied. -u allowed for root only"); + break; + case 't': + tty = optarg; + break; + case 'v': + wl.verbose = 1; + break; + case 'h': + help("weston-launch"); + exit(EXIT_FAILURE); + } + } + + if ((argc - optind) > (MAX_ARGV_SIZE - 6)) + error(1, E2BIG, "Too many arguments to pass to weston"); + + if (wl.new_user) + wl.pw = getpwnam(wl.new_user); + else + wl.pw = getpwuid(getuid()); + if (wl.pw == NULL) + error(1, errno, "failed to get username"); + + if (!weston_launch_allowed(&wl)) + error(1, 0, "Permission denied. You should either:\n" +#ifdef HAVE_SYSTEMD_LOGIN + " - run from an active and local (systemd) session.\n" +#else + " - enable systemd session support for weston-launch.\n" +#endif + " - or add yourself to the 'weston-launch' group."); + + if (setup_tty(&wl, tty) < 0) + exit(EXIT_FAILURE); + + if (wl.new_user && setup_pam(&wl) < 0) + exit(EXIT_FAILURE); + + if (setup_launcher_socket(&wl) < 0) + exit(EXIT_FAILURE); + + if (setup_signals(&wl) < 0) + exit(EXIT_FAILURE); + + wl.child = fork(); + if (wl.child == -1) { + error(1, errno, "fork failed"); + exit(EXIT_FAILURE); + } + + if (wl.child == 0) + launch_compositor(&wl, argc - optind, argv + optind); + + close(wl.sock[1]); + if (wl.tty != STDIN_FILENO) + close(wl.tty); + + while (1) { + struct pollfd fds[2]; + int n; + + fds[0].fd = wl.sock[0]; + fds[0].events = POLLIN; + fds[1].fd = wl.signalfd; + fds[1].events = POLLIN; + + n = poll(fds, 2, -1); + if (n < 0) + error(0, errno, "poll failed"); + if (fds[0].revents & POLLIN) + handle_socket_msg(&wl); + if (fds[1].revents) + handle_signal(&wl); + } + + return 0; +} |