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-rw-r--r--src/libcore/namespace.c727
1 files changed, 727 insertions, 0 deletions
diff --git a/src/libcore/namespace.c b/src/libcore/namespace.c
new file mode 100644
index 0000000000..4fa381db5b
--- /dev/null
+++ b/src/libcore/namespace.c
@@ -0,0 +1,727 @@
+/***
+ 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 Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <sched.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <linux/fs.h>
+
+#include "alloc-util.h"
+#include "dev-setup.h"
+#include "fd-util.h"
+#include "loopback-setup.h"
+#include "missing.h"
+#include "mkdir.h"
+#include "mount-util.h"
+#include "namespace.h"
+#include "path-util.h"
+#include "selinux-util.h"
+#include "socket-util.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "strv.h"
+#include "umask-util.h"
+#include "user-util.h"
+#include "util.h"
+
+typedef enum MountMode {
+ /* This is ordered by priority! */
+ INACCESSIBLE,
+ READONLY,
+ PRIVATE_TMP,
+ PRIVATE_VAR_TMP,
+ PRIVATE_DEV,
+ PRIVATE_BUS_ENDPOINT,
+ READWRITE
+} MountMode;
+
+typedef struct BindMount {
+ const char *path;
+ MountMode mode;
+ bool done;
+ bool ignore;
+} BindMount;
+
+static int append_mounts(BindMount **p, char **strv, MountMode mode) {
+ char **i;
+
+ assert(p);
+
+ STRV_FOREACH(i, strv) {
+
+ (*p)->ignore = false;
+ (*p)->done = false;
+
+ if ((mode == INACCESSIBLE || mode == READONLY || mode == READWRITE) && (*i)[0] == '-') {
+ (*p)->ignore = true;
+ (*i)++;
+ }
+
+ if (!path_is_absolute(*i))
+ return -EINVAL;
+
+ (*p)->path = *i;
+ (*p)->mode = mode;
+ (*p)++;
+ }
+
+ return 0;
+}
+
+static int mount_path_compare(const void *a, const void *b) {
+ const BindMount *p = a, *q = b;
+ int d;
+
+ d = path_compare(p->path, q->path);
+
+ if (d == 0) {
+ /* 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 */
+ return d;
+}
+
+static void drop_duplicates(BindMount *m, unsigned *n) {
+ BindMount *f, *t, *previous;
+
+ assert(m);
+ assert(n);
+
+ for (f = m, t = m, previous = NULL; f < m+*n; f++) {
+
+ /* The first one wins */
+ if (previous && path_equal(f->path, previous->path))
+ continue;
+
+ *t = *f;
+
+ previous = t;
+
+ t++;
+ }
+
+ *n = t - m;
+}
+
+static int mount_dev(BindMount *m) {
+ static const char devnodes[] =
+ "/dev/null\0"
+ "/dev/zero\0"
+ "/dev/full\0"
+ "/dev/random\0"
+ "/dev/urandom\0"
+ "/dev/tty\0";
+
+ char temporary_mount[] = "/tmp/namespace-dev-XXXXXX";
+ const char *d, *dev = NULL, *devpts = NULL, *devshm = NULL, *devhugepages = NULL, *devmqueue = NULL, *devlog = NULL, *devptmx = NULL;
+ _cleanup_umask_ mode_t u;
+ int r;
+
+ assert(m);
+
+ u = umask(0000);
+
+ if (!mkdtemp(temporary_mount))
+ return -errno;
+
+ dev = strjoina(temporary_mount, "/dev");
+ (void) mkdir(dev, 0755);
+ if (mount("tmpfs", dev, "tmpfs", MS_NOSUID|MS_STRICTATIME, "mode=755") < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ devpts = strjoina(temporary_mount, "/dev/pts");
+ (void) mkdir(devpts, 0755);
+ if (mount("/dev/pts", devpts, NULL, MS_BIND, NULL) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ devptmx = strjoina(temporary_mount, "/dev/ptmx");
+ if (symlink("pts/ptmx", devptmx) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ devshm = strjoina(temporary_mount, "/dev/shm");
+ (void) mkdir(devshm, 01777);
+ r = mount("/dev/shm", devshm, NULL, MS_BIND, NULL);
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ devmqueue = strjoina(temporary_mount, "/dev/mqueue");
+ (void) mkdir(devmqueue, 0755);
+ (void) mount("/dev/mqueue", devmqueue, NULL, MS_BIND, NULL);
+
+ devhugepages = strjoina(temporary_mount, "/dev/hugepages");
+ (void) mkdir(devhugepages, 0755);
+ (void) mount("/dev/hugepages", devhugepages, NULL, MS_BIND, NULL);
+
+ devlog = strjoina(temporary_mount, "/dev/log");
+ (void) symlink("/run/systemd/journal/dev-log", devlog);
+
+ NULSTR_FOREACH(d, devnodes) {
+ _cleanup_free_ char *dn = NULL;
+ struct stat st;
+
+ r = stat(d, &st);
+ if (r < 0) {
+
+ if (errno == ENOENT)
+ continue;
+
+ r = -errno;
+ goto fail;
+ }
+
+ if (!S_ISBLK(st.st_mode) &&
+ !S_ISCHR(st.st_mode)) {
+ r = -EINVAL;
+ goto fail;
+ }
+
+ if (st.st_rdev == 0)
+ continue;
+
+ dn = strappend(temporary_mount, d);
+ if (!dn) {
+ r = -ENOMEM;
+ goto fail;
+ }
+
+ mac_selinux_create_file_prepare(d, st.st_mode);
+ r = mknod(dn, st.st_mode, st.st_rdev);
+ mac_selinux_create_file_clear();
+
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+ }
+
+ dev_setup(temporary_mount, UID_INVALID, GID_INVALID);
+
+ /* Create the /dev directory if missing. It is more likely to be
+ * missing when the service is started with RootDirectory. This is
+ * consistent with mount units creating the mount points when missing.
+ */
+ (void) mkdir_p_label(m->path, 0755);
+
+ if (mount(dev, m->path, NULL, MS_MOVE, NULL) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ rmdir(dev);
+ rmdir(temporary_mount);
+
+ return 0;
+
+fail:
+ if (devpts)
+ umount(devpts);
+
+ if (devshm)
+ umount(devshm);
+
+ if (devhugepages)
+ umount(devhugepages);
+
+ if (devmqueue)
+ umount(devmqueue);
+
+ umount(dev);
+ rmdir(dev);
+ rmdir(temporary_mount);
+
+ return r;
+}
+
+static int mount_kdbus(BindMount *m) {
+
+ char temporary_mount[] = "/tmp/kdbus-dev-XXXXXX";
+ _cleanup_free_ char *basepath = NULL;
+ _cleanup_umask_ mode_t u;
+ char *busnode = NULL, *root;
+ struct stat st;
+ int r;
+
+ assert(m);
+
+ u = umask(0000);
+
+ if (!mkdtemp(temporary_mount))
+ return log_error_errno(errno, "Failed create temp dir: %m");
+
+ root = strjoina(temporary_mount, "/kdbus");
+ (void) mkdir(root, 0755);
+ if (mount("tmpfs", root, "tmpfs", MS_NOSUID|MS_STRICTATIME, "mode=777") < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ /* create a new /dev/null dev node copy so we have some fodder to
+ * bind-mount the custom endpoint over. */
+ if (stat("/dev/null", &st) < 0) {
+ r = log_error_errno(errno, "Failed to stat /dev/null: %m");
+ goto fail;
+ }
+
+ busnode = strjoina(root, "/bus");
+ if (mknod(busnode, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) {
+ r = log_error_errno(errno, "mknod() for %s failed: %m",
+ busnode);
+ goto fail;
+ }
+
+ r = mount(m->path, busnode, NULL, MS_BIND, NULL);
+ if (r < 0) {
+ r = log_error_errno(errno, "bind mount of %s failed: %m",
+ m->path);
+ goto fail;
+ }
+
+ basepath = dirname_malloc(m->path);
+ if (!basepath) {
+ r = -ENOMEM;
+ goto fail;
+ }
+
+ if (mount(root, basepath, NULL, MS_MOVE, NULL) < 0) {
+ r = log_error_errno(errno, "bind mount of %s failed: %m",
+ basepath);
+ goto fail;
+ }
+
+ rmdir(temporary_mount);
+ return 0;
+
+fail:
+ if (busnode) {
+ umount(busnode);
+ unlink(busnode);
+ }
+
+ umount(root);
+ rmdir(root);
+ rmdir(temporary_mount);
+
+ return r;
+}
+
+static int apply_mount(
+ BindMount *m,
+ const char *tmp_dir,
+ const char *var_tmp_dir) {
+
+ const char *what;
+ int r;
+
+ assert(m);
+
+ switch (m->mode) {
+
+ case INACCESSIBLE:
+
+ /* First, get rid of everything that is below if there
+ * is anything... Then, overmount it with an
+ * inaccessible directory. */
+ umount_recursive(m->path, 0);
+
+ what = "/run/systemd/inaccessible";
+ break;
+
+ case READONLY:
+ case READWRITE:
+ /* Nothing to mount here, we just later toggle the
+ * MS_RDONLY bit for the mount point */
+ return 0;
+
+ case PRIVATE_TMP:
+ what = tmp_dir;
+ break;
+
+ case PRIVATE_VAR_TMP:
+ what = var_tmp_dir;
+ break;
+
+ case PRIVATE_DEV:
+ return mount_dev(m);
+
+ case PRIVATE_BUS_ENDPOINT:
+ return mount_kdbus(m);
+
+ default:
+ assert_not_reached("Unknown mode");
+ }
+
+ assert(what);
+
+ r = mount(what, m->path, NULL, MS_BIND|MS_REC, NULL);
+ if (r >= 0)
+ log_debug("Successfully mounted %s to %s", what, m->path);
+ else if (m->ignore && errno == ENOENT)
+ return 0;
+
+ return r;
+}
+
+static int make_read_only(BindMount *m) {
+ int r;
+
+ assert(m);
+
+ if (IN_SET(m->mode, INACCESSIBLE, READONLY))
+ r = bind_remount_recursive(m->path, true);
+ else if (IN_SET(m->mode, READWRITE, PRIVATE_TMP, PRIVATE_VAR_TMP, PRIVATE_DEV))
+ r = bind_remount_recursive(m->path, false);
+ else
+ r = 0;
+
+ if (m->ignore && r == -ENOENT)
+ return 0;
+
+ return r;
+}
+
+int setup_namespace(
+ const char* root_directory,
+ char** read_write_dirs,
+ char** read_only_dirs,
+ char** inaccessible_dirs,
+ const char* tmp_dir,
+ const char* var_tmp_dir,
+ const char* bus_endpoint_path,
+ bool private_dev,
+ ProtectHome protect_home,
+ ProtectSystem protect_system,
+ unsigned long mount_flags) {
+
+ BindMount *m, *mounts = NULL;
+ unsigned n;
+ int r = 0;
+
+ if (mount_flags == 0)
+ mount_flags = MS_SHARED;
+
+ if (unshare(CLONE_NEWNS) < 0)
+ return -errno;
+
+ n = !!tmp_dir + !!var_tmp_dir + !!bus_endpoint_path +
+ strv_length(read_write_dirs) +
+ strv_length(read_only_dirs) +
+ strv_length(inaccessible_dirs) +
+ private_dev +
+ (protect_home != PROTECT_HOME_NO ? 3 : 0) +
+ (protect_system != PROTECT_SYSTEM_NO ? 2 : 0) +
+ (protect_system == PROTECT_SYSTEM_FULL ? 1 : 0);
+
+ if (n > 0) {
+ m = mounts = (BindMount *) alloca0(n * sizeof(BindMount));
+ r = append_mounts(&m, read_write_dirs, READWRITE);
+ if (r < 0)
+ return r;
+
+ r = append_mounts(&m, read_only_dirs, READONLY);
+ if (r < 0)
+ return r;
+
+ r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE);
+ if (r < 0)
+ return r;
+
+ if (tmp_dir) {
+ m->path = prefix_roota(root_directory, "/tmp");
+ m->mode = PRIVATE_TMP;
+ m++;
+ }
+
+ if (var_tmp_dir) {
+ m->path = prefix_roota(root_directory, "/var/tmp");
+ m->mode = PRIVATE_VAR_TMP;
+ m++;
+ }
+
+ if (private_dev) {
+ m->path = prefix_roota(root_directory, "/dev");
+ m->mode = PRIVATE_DEV;
+ m++;
+ }
+
+ if (bus_endpoint_path) {
+ m->path = prefix_roota(root_directory, bus_endpoint_path);
+ m->mode = PRIVATE_BUS_ENDPOINT;
+ m++;
+ }
+
+ if (protect_home != PROTECT_HOME_NO) {
+ const char *home_dir, *run_user_dir, *root_dir;
+
+ home_dir = prefix_roota(root_directory, "/home");
+ home_dir = strjoina("-", home_dir);
+ run_user_dir = prefix_roota(root_directory, "/run/user");
+ run_user_dir = strjoina("-", run_user_dir);
+ root_dir = prefix_roota(root_directory, "/root");
+ root_dir = strjoina("-", root_dir);
+
+ r = append_mounts(&m, STRV_MAKE(home_dir, run_user_dir, root_dir),
+ protect_home == PROTECT_HOME_READ_ONLY ? READONLY : INACCESSIBLE);
+ if (r < 0)
+ return r;
+ }
+
+ if (protect_system != PROTECT_SYSTEM_NO) {
+ const char *usr_dir, *boot_dir, *etc_dir;
+
+ usr_dir = prefix_roota(root_directory, "/usr");
+ boot_dir = prefix_roota(root_directory, "/boot");
+ boot_dir = strjoina("-", boot_dir);
+ etc_dir = prefix_roota(root_directory, "/etc");
+
+ r = append_mounts(&m, protect_system == PROTECT_SYSTEM_FULL
+ ? STRV_MAKE(usr_dir, boot_dir, etc_dir)
+ : STRV_MAKE(usr_dir, boot_dir), READONLY);
+ if (r < 0)
+ return r;
+ }
+
+ assert(mounts + n == m);
+
+ qsort(mounts, n, sizeof(BindMount), mount_path_compare);
+ drop_duplicates(mounts, &n);
+ }
+
+ if (n > 0 || root_directory) {
+ /* Remount / as SLAVE so that nothing now mounted in the namespace
+ shows up in the parent */
+ if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0)
+ return -errno;
+ }
+
+ if (root_directory) {
+ /* Turn directory into bind mount */
+ if (mount(root_directory, root_directory, NULL, MS_BIND|MS_REC, NULL) < 0)
+ return -errno;
+ }
+
+ if (n > 0) {
+ for (m = mounts; m < mounts + n; ++m) {
+ r = apply_mount(m, tmp_dir, var_tmp_dir);
+ if (r < 0)
+ goto fail;
+ }
+
+ for (m = mounts; m < mounts + n; ++m) {
+ r = make_read_only(m);
+ if (r < 0)
+ goto fail;
+ }
+ }
+
+ if (root_directory) {
+ /* MS_MOVE does not work on MS_SHARED so the remount MS_SHARED will be done later */
+ r = mount_move_root(root_directory);
+
+ /* at this point, we cannot rollback */
+ if (r < 0)
+ return r;
+ }
+
+ /* Remount / as the desired mode. Not that this will not
+ * reestablish propagation from our side to the host, since
+ * what's disconnected is disconnected. */
+ if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0)
+ /* at this point, we cannot rollback */
+ return -errno;
+
+ return 0;
+
+fail:
+ if (n > 0) {
+ for (m = mounts; m < mounts + n; ++m)
+ if (m->done)
+ (void) umount2(m->path, MNT_DETACH);
+ }
+
+ return r;
+}
+
+static int setup_one_tmp_dir(const char *id, const char *prefix, char **path) {
+ _cleanup_free_ char *x = NULL;
+ char bid[SD_ID128_STRING_MAX];
+ sd_id128_t boot_id;
+ int r;
+
+ assert(id);
+ assert(prefix);
+ assert(path);
+
+ /* We include the boot id in the directory so that after a
+ * reboot we can easily identify obsolete directories. */
+
+ r = sd_id128_get_boot(&boot_id);
+ if (r < 0)
+ return r;
+
+ x = strjoin(prefix, "/systemd-private-", sd_id128_to_string(boot_id, bid), "-", id, "-XXXXXX", NULL);
+ if (!x)
+ return -ENOMEM;
+
+ RUN_WITH_UMASK(0077)
+ if (!mkdtemp(x))
+ return -errno;
+
+ RUN_WITH_UMASK(0000) {
+ char *y;
+
+ y = strjoina(x, "/tmp");
+
+ if (mkdir(y, 0777 | S_ISVTX) < 0)
+ return -errno;
+ }
+
+ *path = x;
+ x = NULL;
+
+ return 0;
+}
+
+int setup_tmp_dirs(const char *id, char **tmp_dir, char **var_tmp_dir) {
+ char *a, *b;
+ int r;
+
+ assert(id);
+ assert(tmp_dir);
+ assert(var_tmp_dir);
+
+ r = setup_one_tmp_dir(id, "/tmp", &a);
+ if (r < 0)
+ return r;
+
+ r = setup_one_tmp_dir(id, "/var/tmp", &b);
+ if (r < 0) {
+ char *t;
+
+ t = strjoina(a, "/tmp");
+ rmdir(t);
+ rmdir(a);
+
+ free(a);
+ return r;
+ }
+
+ *tmp_dir = a;
+ *var_tmp_dir = b;
+
+ return 0;
+}
+
+int setup_netns(int netns_storage_socket[2]) {
+ _cleanup_close_ int netns = -1;
+ int r, q;
+
+ assert(netns_storage_socket);
+ assert(netns_storage_socket[0] >= 0);
+ assert(netns_storage_socket[1] >= 0);
+
+ /* We use the passed socketpair as a storage buffer for our
+ * namespace reference fd. Whatever process runs this first
+ * shall create a new namespace, all others should just join
+ * it. To serialize that we use a file lock on the socket
+ * pair.
+ *
+ * It's a bit crazy, but hey, works great! */
+
+ if (lockf(netns_storage_socket[0], F_LOCK, 0) < 0)
+ return -errno;
+
+ netns = receive_one_fd(netns_storage_socket[0], MSG_DONTWAIT);
+ if (netns == -EAGAIN) {
+ /* Nothing stored yet, so let's create a new namespace */
+
+ if (unshare(CLONE_NEWNET) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ loopback_setup();
+
+ netns = open("/proc/self/ns/net", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (netns < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = 1;
+
+ } else if (netns < 0) {
+ r = netns;
+ goto fail;
+
+ } else {
+ /* Yay, found something, so let's join the namespace */
+ if (setns(netns, CLONE_NEWNET) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = 0;
+ }
+
+ q = send_one_fd(netns_storage_socket[1], netns, MSG_DONTWAIT);
+ if (q < 0) {
+ r = q;
+ goto fail;
+ }
+
+fail:
+ lockf(netns_storage_socket[0], F_ULOCK, 0);
+ return r;
+}
+
+static const char *const protect_home_table[_PROTECT_HOME_MAX] = {
+ [PROTECT_HOME_NO] = "no",
+ [PROTECT_HOME_YES] = "yes",
+ [PROTECT_HOME_READ_ONLY] = "read-only",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(protect_home, ProtectHome);
+
+static const char *const protect_system_table[_PROTECT_SYSTEM_MAX] = {
+ [PROTECT_SYSTEM_NO] = "no",
+ [PROTECT_SYSTEM_YES] = "yes",
+ [PROTECT_SYSTEM_FULL] = "full",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(protect_system, ProtectSystem);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-16 20:18:53 +0000