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, *devlog = NULL, *devptmx = 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 devptmx = strappenda(temporary_mount, "/dev/ptmx");
172 symlink("pts/ptmx", devptmx);
174 devshm = strappenda(temporary_mount, "/dev/shm");
175 mkdir(devshm, 01777);
176 r = mount("/dev/shm", devshm, NULL, MS_BIND, NULL);
182 devmqueue = strappenda(temporary_mount, "/dev/mqueue");
183 mkdir(devmqueue, 0755);
184 mount("/dev/mqueue", devmqueue, NULL, MS_BIND, NULL);
186 devkdbus = strappenda(temporary_mount, "/dev/kdbus");
187 mkdir(devkdbus, 0755);
188 mount("/dev/kdbus", devkdbus, NULL, MS_BIND, NULL);
190 devhugepages = strappenda(temporary_mount, "/dev/hugepages");
191 mkdir(devhugepages, 0755);
192 mount("/dev/hugepages", devhugepages, NULL, MS_BIND, NULL);
194 devlog = strappenda(temporary_mount, "/dev/log");
195 symlink("/run/systemd/journal/dev-log", devlog);
197 NULSTR_FOREACH(d, devnodes) {
198 _cleanup_free_ char *dn = NULL;
211 if (!S_ISBLK(st.st_mode) &&
212 !S_ISCHR(st.st_mode)) {
220 dn = strappend(temporary_mount, d);
226 r = mknod(dn, st.st_mode, st.st_rdev);
233 dev_setup(temporary_mount);
235 if (mount(dev, "/dev/", NULL, MS_MOVE, NULL) < 0) {
241 rmdir(temporary_mount);
256 umount(devhugepages);
266 rmdir(temporary_mount);
271 static int apply_mount(
274 const char *var_tmp_dir) {
287 what = "/run/systemd/inaccessible";
299 case PRIVATE_VAR_TMP:
304 assert_not_reached("Unknown mode");
309 r = mount(what, m->path, NULL, MS_BIND|MS_REC, NULL);
311 log_debug("Successfully mounted %s to %s", what, m->path);
312 else if (m->ignore && errno == ENOENT)
318 static int make_read_only(BindMount *m) {
323 if (m->mode != INACCESSIBLE && m->mode != READONLY)
326 r = mount(NULL, m->path, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL);
327 if (r < 0 && !(m->ignore && errno == ENOENT))
334 char** read_write_dirs,
335 char** read_only_dirs,
336 char** inaccessible_dirs,
340 ProtectedHome protected_home,
341 bool read_only_system,
342 unsigned mount_flags) {
344 BindMount *m, *mounts = NULL;
348 if (mount_flags == 0)
349 mount_flags = MS_SHARED;
351 if (unshare(CLONE_NEWNS) < 0)
354 n = !!tmp_dir + !!var_tmp_dir +
355 strv_length(read_write_dirs) +
356 strv_length(read_only_dirs) +
357 strv_length(inaccessible_dirs) +
359 (protected_home != PROTECTED_HOME_NO ? 2 : 0) +
360 (read_only_system ? 2 : 0);
363 m = mounts = (BindMount *) alloca(n * sizeof(BindMount));
364 r = append_mounts(&m, read_write_dirs, READWRITE);
368 r = append_mounts(&m, read_only_dirs, READONLY);
372 r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE);
378 m->mode = PRIVATE_TMP;
383 m->path = "/var/tmp";
384 m->mode = PRIVATE_VAR_TMP;
390 m->mode = PRIVATE_DEV;
394 if (protected_home != PROTECTED_HOME_NO) {
395 r = append_mounts(&m, STRV_MAKE("-/home", "-/run/user"), protected_home == PROTECTED_HOME_READ_ONLY ? READONLY : INACCESSIBLE);
400 if (read_only_system) {
401 r = append_mounts(&m, STRV_MAKE("/usr", "-/boot"), READONLY);
406 assert(mounts + n == m);
408 qsort(mounts, n, sizeof(BindMount), mount_path_compare);
409 drop_duplicates(mounts, &n);
413 /* Remount / as SLAVE so that nothing now mounted in the namespace
414 shows up in the parent */
415 if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0)
418 for (m = mounts; m < mounts + n; ++m) {
419 r = apply_mount(m, tmp_dir, var_tmp_dir);
424 for (m = mounts; m < mounts + n; ++m) {
425 r = make_read_only(m);
431 /* Remount / as the desired mode. Not that this will not
432 * reestablish propagation from our side to the host, since
433 * what's disconnected is disconnected. */
434 if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
443 for (m = mounts; m < mounts + n; ++m)
445 umount2(m->path, MNT_DETACH);
451 static int setup_one_tmp_dir(const char *id, const char *prefix, char **path) {
452 _cleanup_free_ char *x = NULL;
453 char bid[SD_ID128_STRING_MAX];
461 /* We include the boot id in the directory so that after a
462 * reboot we can easily identify obsolete directories. */
464 r = sd_id128_get_boot(&boot_id);
468 x = strjoin(prefix, "/systemd-private-", sd_id128_to_string(boot_id, bid), "-", id, "-XXXXXX", NULL);
476 RUN_WITH_UMASK(0000) {
479 y = strappenda(x, "/tmp");
481 if (mkdir(y, 0777 | S_ISVTX) < 0)
491 int setup_tmp_dirs(const char *id, char **tmp_dir, char **var_tmp_dir) {
499 r = setup_one_tmp_dir(id, "/tmp", &a);
503 r = setup_one_tmp_dir(id, "/var/tmp", &b);
507 t = strappenda(a, "/tmp");
521 int setup_netns(int netns_storage_socket[2]) {
522 _cleanup_close_ int netns = -1;
524 struct cmsghdr cmsghdr;
525 uint8_t buf[CMSG_SPACE(sizeof(int))];
528 .msg_control = &control,
529 .msg_controllen = sizeof(control),
531 struct cmsghdr *cmsg;
534 assert(netns_storage_socket);
535 assert(netns_storage_socket[0] >= 0);
536 assert(netns_storage_socket[1] >= 0);
538 /* We use the passed socketpair as a storage buffer for our
539 * namespace reference fd. Whatever process runs this first
540 * shall create a new namespace, all others should just join
541 * it. To serialize that we use a file lock on the socket
544 * It's a bit crazy, but hey, works great! */
546 if (lockf(netns_storage_socket[0], F_LOCK, 0) < 0)
549 if (recvmsg(netns_storage_socket[0], &mh, MSG_DONTWAIT|MSG_CMSG_CLOEXEC) < 0) {
550 if (errno != EAGAIN) {
555 /* Nothing stored yet, so let's create a new namespace */
557 if (unshare(CLONE_NEWNET) < 0) {
564 netns = open("/proc/self/ns/net", O_RDONLY|O_CLOEXEC|O_NOCTTY);
572 /* Yay, found something, so let's join the namespace */
574 for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) {
575 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
576 assert(cmsg->cmsg_len == CMSG_LEN(sizeof(int)));
577 netns = *(int*) CMSG_DATA(cmsg);
581 if (setns(netns, CLONE_NEWNET) < 0) {
589 cmsg = CMSG_FIRSTHDR(&mh);
590 cmsg->cmsg_level = SOL_SOCKET;
591 cmsg->cmsg_type = SCM_RIGHTS;
592 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
593 memcpy(CMSG_DATA(cmsg), &netns, sizeof(int));
594 mh.msg_controllen = cmsg->cmsg_len;
596 if (sendmsg(netns_storage_socket[1], &mh, MSG_DONTWAIT|MSG_NOSIGNAL) < 0) {
602 lockf(netns_storage_socket[0], F_ULOCK, 0);
607 static const char *const protected_home_table[_PROTECTED_HOME_MAX] = {
608 [PROTECTED_HOME_NO] = "no",
609 [PROTECTED_HOME_YES] = "yes",
610 [PROTECTED_HOME_READ_ONLY] = "read-only",
613 DEFINE_STRING_TABLE_LOOKUP(protected_home, ProtectedHome);