Commit 2d27873f authored by Giovanni Campagna's avatar Giovanni Campagna
Browse files

mutter-launch: simplify by removing features we don't need

Remove the ability to launch as a different user, which we don't
need because we're spawned by gdm or by the user manually on the
command line.
At the same time, require an active local session, and remove
the ability to run from anywhere by being in the right user group
(which automatically gives you root-like privileges)

https://bugzilla.gnome.org/show_bug.cgi?id=705861
parent fd40a122
......@@ -53,9 +53,7 @@
#include <xf86drm.h>
#ifdef HAVE_SYSTEMD_LOGIN
#include <systemd/sd-login.h>
#endif
#include "weston-launch.h"
......@@ -78,60 +76,15 @@ struct weston_launch {
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) &&
......@@ -142,52 +95,10 @@ weston_launch_allowed(struct weston_launch *wl)
}
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)
{
......@@ -468,27 +379,14 @@ setup_tty(struct weston_launch *wl, const char *tty)
struct stat buf;
char *t;
if (!wl->new_user) {
wl->tty = STDIN_FILENO;
} else if (tty) {
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);
wl->tty = STDIN_FILENO;
}
if (wl->tty < 0)
......@@ -507,39 +405,6 @@ setup_tty(struct weston_launch *wl, const char *tty)
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)
{
......@@ -561,8 +426,6 @@ launch_compositor(struct weston_launch *wl, int argc, char *argv[])
if (wl->verbose)
printf("weston-launch: spawned weston with pid: %d\n", getpid());
if (wl->new_user)
setup_session(wl);
drop_privileges(wl);
......@@ -611,7 +474,6 @@ main(int argc, char *argv[])
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' },
......@@ -622,11 +484,6 @@ main(int argc, char *argv[])
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;
......@@ -646,28 +503,16 @@ main(int argc, char *argv[])
strcmp (argv[optind], "gnome-shell-wayland"))
error(1, 0, "mutter-launch can only be used to launch mutter or gnome-shell");
if (wl.new_user)
wl.pw = getpwnam(wl.new_user);
else
wl.pw = getpwuid(getuid());
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.");
error(1, 0, "Permission denied. You must run from an active and local (systemd) session.");
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);
......
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