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>
36 #include "path-util.h"
37 #include "namespace.h"
41 typedef enum MountMode {
42 /* This is ordered by priority! */
50 typedef struct BindMount {
57 static int append_mounts(BindMount **p, char **strv, MountMode mode) {
60 STRV_FOREACH(i, strv) {
64 if ((mode == INACCESSIBLE || mode == READONLY) && (*i)[0] == '-') {
69 if (!path_is_absolute(*i))
80 static int mount_path_compare(const void *a, const void *b) {
81 const BindMount *p = a, *q = b;
83 if (path_equal(p->path, q->path)) {
85 /* If the paths are equal, check the mode */
86 if (p->mode < q->mode)
89 if (p->mode > q->mode)
95 /* If the paths are not equal, then order prefixes first */
96 if (path_startswith(p->path, q->path))
99 if (path_startswith(q->path, p->path))
105 static void drop_duplicates(BindMount *m, unsigned *n) {
106 BindMount *f, *t, *previous;
111 for (f = m, t = m, previous = NULL; f < m+*n; f++) {
113 /* The first one wins */
114 if (previous && path_equal(f->path, previous->path))
128 static int apply_mount(
131 const char *var_tmp_dir) {
141 what = "/run/systemd/inaccessible";
153 case PRIVATE_VAR_TMP:
158 assert_not_reached("Unknown mode");
163 r = mount(what, m->path, NULL, MS_BIND|MS_REC, NULL);
165 log_debug("Successfully mounted %s to %s", what, m->path);
166 else if (m->ignore && errno == ENOENT)
172 static int make_read_only(BindMount *m) {
177 if (m->mode != INACCESSIBLE && m->mode != READONLY)
180 r = mount(NULL, m->path, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL);
181 if (r < 0 && !(m->ignore && errno == ENOENT))
187 int setup_tmpdirs(const char *unit_id,
189 char **var_tmp_dir) {
191 _cleanup_free_ char *tmp = NULL, *var = NULL;
196 tmp = strjoin("/tmp/systemd-", unit_id, "-XXXXXXX", NULL);
197 var = strjoin("/var/tmp/systemd-", unit_id, "-XXXXXXX", NULL);
199 r = create_tmp_dir(tmp, tmp_dir);
203 r = create_tmp_dir(var, var_tmp_dir);
216 int setup_namespace(char** read_write_dirs,
217 char** read_only_dirs,
218 char** inaccessible_dirs,
222 unsigned mount_flags) {
224 unsigned n = strv_length(read_write_dirs) +
225 strv_length(read_only_dirs) +
226 strv_length(inaccessible_dirs) +
227 (private_tmp ? 2 : 0);
228 BindMount *m, *mounts = NULL;
232 mount_flags = MS_SHARED;
234 if (unshare(CLONE_NEWNS) < 0)
238 m = mounts = (BindMount *) alloca(n * sizeof(BindMount));
239 if ((r = append_mounts(&m, read_write_dirs, READWRITE)) < 0 ||
240 (r = append_mounts(&m, read_only_dirs, READONLY)) < 0 ||
241 (r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE)) < 0)
246 m->mode = PRIVATE_TMP;
249 m->path = "/var/tmp";
250 m->mode = PRIVATE_VAR_TMP;
254 assert(mounts + n == m);
256 qsort(mounts, n, sizeof(BindMount), mount_path_compare);
257 drop_duplicates(mounts, &n);
260 /* Remount / as SLAVE so that nothing now mounted in the namespace
261 shows up in the parent */
262 if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0)
265 for (m = mounts; m < mounts + n; ++m) {
266 r = apply_mount(m, tmp_dir, var_tmp_dir);
271 for (m = mounts; m < mounts + n; ++m) {
272 r = make_read_only(m);
277 /* Remount / as the desired mode */
278 if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
286 for (m = mounts; m < mounts + n; ++m) {
288 umount2(m->path, MNT_DETACH);