1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
23 #include <sys/mount.h>
28 #include <sys/types.h>
30 #include <sys/syscall.h>
37 #include "path-util.h"
38 #include "namespace.h"
41 #include "loopback-setup.h"
43 #include "dev-setup.h"
46 typedef enum MountMode {
47 /* This is ordered by priority! */
56 typedef struct BindMount {
63 static int append_mounts(BindMount **p, char **strv, MountMode mode) {
68 STRV_FOREACH(i, strv) {
72 if ((mode == INACCESSIBLE || mode == READONLY || mode == READWRITE) && (*i)[0] == '-') {
77 if (!path_is_absolute(*i))
88 static int mount_path_compare(const void *a, const void *b) {
89 const BindMount *p = a, *q = b;
91 if (path_equal(p->path, q->path)) {
93 /* If the paths are equal, check the mode */
94 if (p->mode < q->mode)
97 if (p->mode > q->mode)
103 /* If the paths are not equal, then order prefixes first */
104 if (path_startswith(p->path, q->path))
107 if (path_startswith(q->path, p->path))
113 static void drop_duplicates(BindMount *m, unsigned *n) {
114 BindMount *f, *t, *previous;
119 for (f = m, t = m, previous = NULL; f < m+*n; f++) {
121 /* The first one wins */
122 if (previous && path_equal(f->path, previous->path))
136 static int mount_dev(BindMount *m) {
137 static const char devnodes[] =
145 char temporary_mount[] = "/tmp/namespace-dev-XXXXXX";
146 const char *d, *dev = NULL, *devpts = NULL, *devshm = NULL, *devkdbus = NULL, *devhugepages = NULL, *devmqueue = NULL;
147 _cleanup_umask_ mode_t u;
154 if (!mkdtemp(temporary_mount))
157 dev = strappenda(temporary_mount, "/dev");
159 if (mount("tmpfs", dev, "tmpfs", MS_NOSUID|MS_STRICTATIME, "mode=755") < 0) {
164 devpts = strappenda(temporary_mount, "/dev/pts");
166 if (mount("/dev/pts", devpts, NULL, MS_BIND, NULL) < 0) {
171 devshm = strappenda(temporary_mount, "/dev/shm");
172 mkdir(devshm, 01777);
173 r = mount("/dev/shm", devshm, NULL, MS_BIND, NULL);
179 devmqueue = strappenda(temporary_mount, "/dev/mqueue");
180 mkdir(devmqueue, 0755);
181 mount("/dev/mqueue", devmqueue, NULL, MS_BIND, NULL);
183 devkdbus = strappenda(temporary_mount, "/dev/kdbus");
184 mkdir(devkdbus, 0755);
185 mount("/dev/kdbus", devkdbus, NULL, MS_BIND, NULL);
187 devhugepages = strappenda(temporary_mount, "/dev/hugepages");
188 mkdir(devhugepages, 0755);
189 mount("/dev/hugepages", devhugepages, NULL, MS_BIND, NULL);
191 NULSTR_FOREACH(d, devnodes) {
192 _cleanup_free_ char *dn = NULL;
205 if (!S_ISBLK(st.st_mode) &&
206 !S_ISCHR(st.st_mode)) {
214 dn = strappend(temporary_mount, d);
220 r = mknod(dn, st.st_mode, st.st_rdev);
227 dev_setup(temporary_mount);
229 if (mount(dev, "/dev/", NULL, MS_MOVE, NULL) < 0) {
235 rmdir(temporary_mount);
250 umount(devhugepages);
260 rmdir(temporary_mount);
265 static int apply_mount(
268 const char *var_tmp_dir) {
281 what = "/run/systemd/inaccessible";
293 case PRIVATE_VAR_TMP:
298 assert_not_reached("Unknown mode");
303 r = mount(what, m->path, NULL, MS_BIND|MS_REC, NULL);
305 log_debug("Successfully mounted %s to %s", what, m->path);
306 else if (m->ignore && errno == ENOENT)
312 static int make_read_only(BindMount *m) {
317 if (m->mode != INACCESSIBLE && m->mode != READONLY)
320 r = mount(NULL, m->path, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL);
321 if (r < 0 && !(m->ignore && errno == ENOENT))
328 char** read_write_dirs,
329 char** read_only_dirs,
330 char** inaccessible_dirs,
334 unsigned mount_flags) {
336 BindMount *m, *mounts = NULL;
340 if (mount_flags == 0)
341 mount_flags = MS_SHARED;
343 if (unshare(CLONE_NEWNS) < 0)
346 n = !!tmp_dir + !!var_tmp_dir +
347 strv_length(read_write_dirs) +
348 strv_length(read_only_dirs) +
349 strv_length(inaccessible_dirs) +
353 m = mounts = (BindMount *) alloca(n * sizeof(BindMount));
354 r = append_mounts(&m, read_write_dirs, READWRITE);
358 r = append_mounts(&m, read_only_dirs, READONLY);
362 r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE);
368 m->mode = PRIVATE_TMP;
373 m->path = "/var/tmp";
374 m->mode = PRIVATE_VAR_TMP;
380 m->mode = PRIVATE_DEV;
384 assert(mounts + n == m);
386 qsort(mounts, n, sizeof(BindMount), mount_path_compare);
387 drop_duplicates(mounts, &n);
390 /* Remount / as SLAVE so that nothing now mounted in the namespace
391 shows up in the parent */
392 if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0)
395 for (m = mounts; m < mounts + n; ++m) {
396 r = apply_mount(m, tmp_dir, var_tmp_dir);
401 for (m = mounts; m < mounts + n; ++m) {
402 r = make_read_only(m);
407 /* Remount / as the desired mode */
408 if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
416 for (m = mounts; m < mounts + n; ++m)
418 umount2(m->path, MNT_DETACH);
423 static int setup_one_tmp_dir(const char *id, const char *prefix, char **path) {
424 _cleanup_free_ char *x = NULL;
425 char bid[SD_ID128_STRING_MAX];
433 /* We include the boot id in the directory so that after a
434 * reboot we can easily identify obsolete directories. */
436 r = sd_id128_get_boot(&boot_id);
440 x = strjoin(prefix, "/systemd-private-", sd_id128_to_string(boot_id, bid), "-", id, "-XXXXXX", NULL);
448 RUN_WITH_UMASK(0000) {
451 y = strappenda(x, "/tmp");
453 if (mkdir(y, 0777 | S_ISVTX) < 0)
463 int setup_tmp_dirs(const char *id, char **tmp_dir, char **var_tmp_dir) {
471 r = setup_one_tmp_dir(id, "/tmp", &a);
475 r = setup_one_tmp_dir(id, "/var/tmp", &b);
479 t = strappenda(a, "/tmp");
493 int setup_netns(int netns_storage_socket[2]) {
494 _cleanup_close_ int netns = -1;
496 struct cmsghdr cmsghdr;
497 uint8_t buf[CMSG_SPACE(sizeof(int))];
500 .msg_control = &control,
501 .msg_controllen = sizeof(control),
503 struct cmsghdr *cmsg;
506 assert(netns_storage_socket);
507 assert(netns_storage_socket[0] >= 0);
508 assert(netns_storage_socket[1] >= 0);
510 /* We use the passed socketpair as a storage buffer for our
511 * namespace reference fd. Whatever process runs this first
512 * shall create a new namespace, all others should just join
513 * it. To serialize that we use a file lock on the socket
516 * It's a bit crazy, but hey, works great! */
518 if (lockf(netns_storage_socket[0], F_LOCK, 0) < 0)
521 if (recvmsg(netns_storage_socket[0], &mh, MSG_DONTWAIT|MSG_CMSG_CLOEXEC) < 0) {
522 if (errno != EAGAIN) {
527 /* Nothing stored yet, so let's create a new namespace */
529 if (unshare(CLONE_NEWNET) < 0) {
536 netns = open("/proc/self/ns/net", O_RDONLY|O_CLOEXEC|O_NOCTTY);
544 /* Yay, found something, so let's join the namespace */
546 for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) {
547 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
548 assert(cmsg->cmsg_len == CMSG_LEN(sizeof(int)));
549 netns = *(int*) CMSG_DATA(cmsg);
553 if (setns(netns, CLONE_NEWNET) < 0) {
561 cmsg = CMSG_FIRSTHDR(&mh);
562 cmsg->cmsg_level = SOL_SOCKET;
563 cmsg->cmsg_type = SCM_RIGHTS;
564 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
565 memcpy(CMSG_DATA(cmsg), &netns, sizeof(int));
566 mh.msg_controllen = cmsg->cmsg_len;
568 if (sendmsg(netns_storage_socket[1], &mh, MSG_DONTWAIT|MSG_NOSIGNAL) < 0) {
574 lockf(netns_storage_socket[0], F_ULOCK, 0);