summaryrefslogtreecommitdiff
path: root/src/core/namespace.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/core/namespace.c')
-rw-r--r--src/core/namespace.c346
1 files changed, 346 insertions, 0 deletions
diff --git a/src/core/namespace.c b/src/core/namespace.c
new file mode 100644
index 000000000..09bc82909
--- /dev/null
+++ b/src/core/namespace.c
@@ -0,0 +1,346 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <sys/mount.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sched.h>
+#include <sys/syscall.h>
+#include <limits.h>
+#include <linux/fs.h>
+
+#include "strv.h"
+#include "util.h"
+#include "namespace.h"
+#include "missing.h"
+
+typedef enum PathMode {
+ /* This is ordered by priority! */
+ INACCESSIBLE,
+ READONLY,
+ PRIVATE,
+ READWRITE
+} PathMode;
+
+typedef struct Path {
+ const char *path;
+ PathMode mode;
+} Path;
+
+static int append_paths(Path **p, char **strv, PathMode mode) {
+ char **i;
+
+ STRV_FOREACH(i, strv) {
+
+ if (!path_is_absolute(*i))
+ return -EINVAL;
+
+ (*p)->path = *i;
+ (*p)->mode = mode;
+ (*p)++;
+ }
+
+ return 0;
+}
+
+static int path_compare(const void *a, const void *b) {
+ const Path *p = a, *q = b;
+
+ if (path_equal(p->path, q->path)) {
+
+ /* If the paths are equal, check the mode */
+ if (p->mode < q->mode)
+ return -1;
+
+ if (p->mode > q->mode)
+ return 1;
+
+ return 0;
+ }
+
+ /* If the paths are not equal, then order prefixes first */
+ if (path_startswith(p->path, q->path))
+ return 1;
+
+ if (path_startswith(q->path, p->path))
+ return -1;
+
+ return 0;
+}
+
+static void drop_duplicates(Path *p, unsigned *n, bool *need_inaccessible, bool *need_private) {
+ Path *f, *t, *previous;
+
+ assert(p);
+ assert(n);
+ assert(need_inaccessible);
+ assert(need_private);
+
+ for (f = p, t = p, previous = NULL; f < p+*n; f++) {
+
+ if (previous && path_equal(f->path, previous->path))
+ continue;
+
+ t->path = f->path;
+ t->mode = f->mode;
+
+ if (t->mode == PRIVATE)
+ *need_private = true;
+
+ if (t->mode == INACCESSIBLE)
+ *need_inaccessible = true;
+
+ previous = t;
+
+ t++;
+ }
+
+ *n = t - p;
+}
+
+static int apply_mount(Path *p, const char *root_dir, const char *inaccessible_dir, const char *private_dir, unsigned long flags) {
+ const char *what;
+ char *where;
+ int r;
+
+ assert(p);
+ assert(root_dir);
+ assert(inaccessible_dir);
+ assert(private_dir);
+
+ if (!(where = strappend(root_dir, p->path)))
+ return -ENOMEM;
+
+ switch (p->mode) {
+
+ case INACCESSIBLE:
+ what = inaccessible_dir;
+ flags |= MS_RDONLY;
+ break;
+
+ case READONLY:
+ flags |= MS_RDONLY;
+ /* Fall through */
+
+ case READWRITE:
+ what = p->path;
+ break;
+
+ case PRIVATE:
+ what = private_dir;
+ break;
+
+ default:
+ assert_not_reached("Unknown mode");
+ }
+
+ if ((r = mount(what, where, NULL, MS_BIND|MS_REC, NULL)) >= 0) {
+ log_debug("Successfully mounted %s to %s", what, where);
+
+ /* The bind mount will always inherit the original
+ * flags. If we want to set any flag we need
+ * to do so in a second independent step. */
+ if (flags)
+ r = mount(NULL, where, NULL, MS_REMOUNT|MS_BIND|MS_REC|flags, NULL);
+
+ /* Avoid exponential growth of trees */
+ if (r >= 0 && path_equal(p->path, "/"))
+ r = mount(NULL, where, NULL, MS_REMOUNT|MS_BIND|MS_UNBINDABLE|flags, NULL);
+
+ if (r < 0) {
+ r = -errno;
+ umount2(where, MNT_DETACH);
+ }
+ }
+
+ free(where);
+ return r;
+}
+
+int setup_namespace(
+ char **writable,
+ char **readable,
+ char **inaccessible,
+ bool private_tmp,
+ unsigned long flags) {
+
+ char
+ tmp_dir[] = "/tmp/systemd-namespace-XXXXXX",
+ root_dir[] = "/tmp/systemd-namespace-XXXXXX/root",
+ old_root_dir[] = "/tmp/systemd-namespace-XXXXXX/root/tmp/old-root-XXXXXX",
+ inaccessible_dir[] = "/tmp/systemd-namespace-XXXXXX/inaccessible",
+ private_dir[] = "/tmp/systemd-namespace-XXXXXX/private";
+
+ Path *paths, *p;
+ unsigned n;
+ bool need_private = false, need_inaccessible = false;
+ bool remove_tmp = false, remove_root = false, remove_old_root = false, remove_inaccessible = false, remove_private = false;
+ int r;
+ const char *t;
+
+ n =
+ strv_length(writable) +
+ strv_length(readable) +
+ strv_length(inaccessible) +
+ (private_tmp ? 2 : 1);
+
+ if (!(paths = new(Path, n)))
+ return -ENOMEM;
+
+ p = paths;
+ if ((r = append_paths(&p, writable, READWRITE)) < 0 ||
+ (r = append_paths(&p, readable, READONLY)) < 0 ||
+ (r = append_paths(&p, inaccessible, INACCESSIBLE)) < 0)
+ goto fail;
+
+ if (private_tmp) {
+ p->path = "/tmp";
+ p->mode = PRIVATE;
+ p++;
+ }
+
+ p->path = "/";
+ p->mode = READWRITE;
+ p++;
+
+ assert(paths + n == p);
+
+ qsort(paths, n, sizeof(Path), path_compare);
+ drop_duplicates(paths, &n, &need_inaccessible, &need_private);
+
+ if (!mkdtemp(tmp_dir)) {
+ r = -errno;
+ goto fail;
+ }
+ remove_tmp = true;
+
+ memcpy(root_dir, tmp_dir, sizeof(tmp_dir)-1);
+ if (mkdir(root_dir, 0777) < 0) {
+ r = -errno;
+ goto fail;
+ }
+ remove_root = true;
+
+ if (need_inaccessible) {
+ memcpy(inaccessible_dir, tmp_dir, sizeof(tmp_dir)-1);
+ if (mkdir(inaccessible_dir, 0) < 0) {
+ r = -errno;
+ goto fail;
+ }
+ remove_inaccessible = true;
+ }
+
+ if (need_private) {
+ mode_t u;
+
+ memcpy(private_dir, tmp_dir, sizeof(tmp_dir)-1);
+
+ u = umask(0000);
+ if (mkdir(private_dir, 0777 + S_ISVTX) < 0) {
+ umask(u);
+
+ r = -errno;
+ goto fail;
+ }
+
+ umask(u);
+ remove_private = true;
+ }
+
+ if (unshare(CLONE_NEWNS) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ /* Remount / as SLAVE so that nothing mounted in the namespace
+ shows up in the parent */
+ if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ for (p = paths; p < paths + n; p++)
+ if ((r = apply_mount(p, root_dir, inaccessible_dir, private_dir, flags)) < 0)
+ goto undo_mounts;
+
+ memcpy(old_root_dir, tmp_dir, sizeof(tmp_dir)-1);
+ if (!mkdtemp(old_root_dir)) {
+ r = -errno;
+ goto undo_mounts;
+ }
+ remove_old_root = true;
+
+ if (chdir(root_dir) < 0) {
+ r = -errno;
+ goto undo_mounts;
+ }
+
+ if (pivot_root(root_dir, old_root_dir) < 0) {
+ r = -errno;
+ goto undo_mounts;
+ }
+
+ t = old_root_dir + sizeof(root_dir) - 1;
+ if (umount2(t, MNT_DETACH) < 0)
+ /* At this point it's too late to turn anything back,
+ * since we are already in the new root. */
+ return -errno;
+
+ if (rmdir(t) < 0)
+ return -errno;
+
+ return 0;
+
+undo_mounts:
+
+ for (p--; p >= paths; p--) {
+ char full_path[PATH_MAX];
+
+ snprintf(full_path, sizeof(full_path), "%s%s", root_dir, p->path);
+ char_array_0(full_path);
+
+ umount2(full_path, MNT_DETACH);
+ }
+
+fail:
+ if (remove_old_root)
+ rmdir(old_root_dir);
+
+ if (remove_inaccessible)
+ rmdir(inaccessible_dir);
+
+ if (remove_private)
+ rmdir(private_dir);
+
+ if (remove_root)
+ rmdir(root_dir);
+
+ if (remove_tmp)
+ rmdir(tmp_dir);
+
+ free(paths);
+
+ return r;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-26 23:38:07 +0000