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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 02:25:50 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 02:25:50 +0000
commit19f4f86bfed21c5326ed2acebe1163f3a83e832b (patch)
treed59b9989ce55ed23693e80974d94c856f1c2c8b1 /src/nspawn/nspawn-mount.c
parentInitial commit. (diff)
downloadsystemd-19f4f86bfed21c5326ed2acebe1163f3a83e832b.tar.xz
systemd-19f4f86bfed21c5326ed2acebe1163f3a83e832b.zip
Adding upstream version 241.upstream/241upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/nspawn/nspawn-mount.c')
-rw-r--r--src/nspawn/nspawn-mount.c1075
1 files changed, 1075 insertions, 0 deletions
diff --git a/src/nspawn/nspawn-mount.c b/src/nspawn/nspawn-mount.c
new file mode 100644
index 0000000..a9af889
--- /dev/null
+++ b/src/nspawn/nspawn-mount.c
@@ -0,0 +1,1075 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <sys/mount.h>
+#include <linux/magic.h>
+
+#include "alloc-util.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "label.h"
+#include "mkdir.h"
+#include "mount-util.h"
+#include "mountpoint-util.h"
+#include "nspawn-mount.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "rm-rf.h"
+#include "set.h"
+#include "stat-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "tmpfile-util.h"
+#include "user-util.h"
+#include "util.h"
+
+CustomMount* custom_mount_add(CustomMount **l, size_t *n, CustomMountType t) {
+ CustomMount *c, *ret;
+
+ assert(l);
+ assert(n);
+ assert(t >= 0);
+ assert(t < _CUSTOM_MOUNT_TYPE_MAX);
+
+ c = reallocarray(*l, *n + 1, sizeof(CustomMount));
+ if (!c)
+ return NULL;
+
+ *l = c;
+ ret = *l + *n;
+ (*n)++;
+
+ *ret = (CustomMount) { .type = t };
+
+ return ret;
+}
+
+void custom_mount_free_all(CustomMount *l, size_t n) {
+ size_t i;
+
+ for (i = 0; i < n; i++) {
+ CustomMount *m = l + i;
+
+ free(m->source);
+ free(m->destination);
+ free(m->options);
+
+ if (m->work_dir) {
+ (void) rm_rf(m->work_dir, REMOVE_ROOT|REMOVE_PHYSICAL);
+ free(m->work_dir);
+ }
+
+ if (m->rm_rf_tmpdir) {
+ (void) rm_rf(m->rm_rf_tmpdir, REMOVE_ROOT|REMOVE_PHYSICAL);
+ free(m->rm_rf_tmpdir);
+ }
+
+ strv_free(m->lower);
+ }
+
+ free(l);
+}
+
+static int custom_mount_compare(const CustomMount *a, const CustomMount *b) {
+ int r;
+
+ r = path_compare(a->destination, b->destination);
+ if (r != 0)
+ return r;
+
+ return CMP(a->type, b->type);
+}
+
+static bool source_path_is_valid(const char *p) {
+ assert(p);
+
+ if (*p == '+')
+ p++;
+
+ return path_is_absolute(p);
+}
+
+static char *resolve_source_path(const char *dest, const char *source) {
+
+ if (!source)
+ return NULL;
+
+ if (source[0] == '+')
+ return prefix_root(dest, source + 1);
+
+ return strdup(source);
+}
+
+int custom_mount_prepare_all(const char *dest, CustomMount *l, size_t n) {
+ size_t i;
+ int r;
+
+ /* Prepare all custom mounts. This will make source we know all temporary directories. This is called in the
+ * parent process, so that we know the temporary directories to remove on exit before we fork off the
+ * children. */
+
+ assert(l || n == 0);
+
+ /* Order the custom mounts, and make sure we have a working directory */
+ typesafe_qsort(l, n, custom_mount_compare);
+
+ for (i = 0; i < n; i++) {
+ CustomMount *m = l + i;
+
+ if (m->source) {
+ char *s;
+
+ s = resolve_source_path(dest, m->source);
+ if (!s)
+ return log_oom();
+
+ free_and_replace(m->source, s);
+ } else {
+ /* No source specified? In that case, use a throw-away temporary directory in /var/tmp */
+
+ m->rm_rf_tmpdir = strdup("/var/tmp/nspawn-temp-XXXXXX");
+ if (!m->rm_rf_tmpdir)
+ return log_oom();
+
+ if (!mkdtemp(m->rm_rf_tmpdir)) {
+ m->rm_rf_tmpdir = mfree(m->rm_rf_tmpdir);
+ return log_error_errno(errno, "Failed to acquire temporary directory: %m");
+ }
+
+ m->source = strjoin(m->rm_rf_tmpdir, "/src");
+ if (!m->source)
+ return log_oom();
+
+ if (mkdir(m->source, 0755) < 0)
+ return log_error_errno(errno, "Failed to create %s: %m", m->source);
+ }
+
+ if (m->type == CUSTOM_MOUNT_OVERLAY) {
+ char **j;
+
+ STRV_FOREACH(j, m->lower) {
+ char *s;
+
+ s = resolve_source_path(dest, *j);
+ if (!s)
+ return log_oom();
+
+ free_and_replace(*j, s);
+ }
+
+ if (m->work_dir) {
+ char *s;
+
+ s = resolve_source_path(dest, m->work_dir);
+ if (!s)
+ return log_oom();
+
+ free_and_replace(m->work_dir, s);
+ } else {
+ assert(m->source);
+
+ r = tempfn_random(m->source, NULL, &m->work_dir);
+ if (r < 0)
+ return log_error_errno(r, "Failed to acquire working directory: %m");
+ }
+
+ (void) mkdir_label(m->work_dir, 0700);
+ }
+ }
+
+ return 0;
+}
+
+int bind_mount_parse(CustomMount **l, size_t *n, const char *s, bool read_only) {
+ _cleanup_free_ char *source = NULL, *destination = NULL, *opts = NULL;
+ const char *p = s;
+ CustomMount *m;
+ int r;
+
+ assert(l);
+ assert(n);
+
+ r = extract_many_words(&p, ":", EXTRACT_DONT_COALESCE_SEPARATORS, &source, &destination, NULL);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -EINVAL;
+ if (r == 1) {
+ destination = strdup(source[0] == '+' ? source+1 : source);
+ if (!destination)
+ return -ENOMEM;
+ }
+ if (r == 2 && !isempty(p)) {
+ opts = strdup(p);
+ if (!opts)
+ return -ENOMEM;
+ }
+
+ if (isempty(source))
+ source = NULL;
+ else if (!source_path_is_valid(source))
+ return -EINVAL;
+
+ if (!path_is_absolute(destination))
+ return -EINVAL;
+
+ m = custom_mount_add(l, n, CUSTOM_MOUNT_BIND);
+ if (!m)
+ return -ENOMEM;
+
+ m->source = source;
+ m->destination = destination;
+ m->read_only = read_only;
+ m->options = opts;
+
+ source = destination = opts = NULL;
+ return 0;
+}
+
+int tmpfs_mount_parse(CustomMount **l, size_t *n, const char *s) {
+ _cleanup_free_ char *path = NULL, *opts = NULL;
+ const char *p = s;
+ CustomMount *m;
+ int r;
+
+ assert(l);
+ assert(n);
+ assert(s);
+
+ r = extract_first_word(&p, &path, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -EINVAL;
+
+ if (isempty(p))
+ opts = strdup("mode=0755");
+ else
+ opts = strdup(p);
+ if (!opts)
+ return -ENOMEM;
+
+ if (!path_is_absolute(path))
+ return -EINVAL;
+
+ m = custom_mount_add(l, n, CUSTOM_MOUNT_TMPFS);
+ if (!m)
+ return -ENOMEM;
+
+ m->destination = TAKE_PTR(path);
+ m->options = TAKE_PTR(opts);
+
+ return 0;
+}
+
+int overlay_mount_parse(CustomMount **l, size_t *n, const char *s, bool read_only) {
+ _cleanup_free_ char *upper = NULL, *destination = NULL;
+ _cleanup_strv_free_ char **lower = NULL;
+ CustomMount *m;
+ int k;
+
+ k = strv_split_extract(&lower, s, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
+ if (k < 0)
+ return k;
+ if (k < 2)
+ return -EADDRNOTAVAIL;
+ if (k == 2) {
+ /* If two parameters are specified, the first one is the lower, the second one the upper directory. And
+ * we'll also define the destination mount point the same as the upper. */
+
+ if (!source_path_is_valid(lower[0]) ||
+ !source_path_is_valid(lower[1]))
+ return -EINVAL;
+
+ upper = TAKE_PTR(lower[1]);
+
+ destination = strdup(upper[0] == '+' ? upper+1 : upper); /* take the destination without "+" prefix */
+ if (!destination)
+ return -ENOMEM;
+ } else {
+ char **i;
+
+ /* If more than two parameters are specified, the last one is the destination, the second to last one
+ * the "upper", and all before that the "lower" directories. */
+
+ destination = lower[k - 1];
+ upper = TAKE_PTR(lower[k - 2]);
+
+ STRV_FOREACH(i, lower)
+ if (!source_path_is_valid(*i))
+ return -EINVAL;
+
+ /* If the upper directory is unspecified, then let's create it automatically as a throw-away directory
+ * in /var/tmp */
+ if (isempty(upper))
+ upper = NULL;
+ else if (!source_path_is_valid(upper))
+ return -EINVAL;
+
+ if (!path_is_absolute(destination))
+ return -EINVAL;
+ }
+
+ m = custom_mount_add(l, n, CUSTOM_MOUNT_OVERLAY);
+ if (!m)
+ return -ENOMEM;
+
+ m->destination = TAKE_PTR(destination);
+ m->source = TAKE_PTR(upper);
+ m->lower = TAKE_PTR(lower);
+ m->read_only = read_only;
+
+ return 0;
+}
+
+int tmpfs_patch_options(
+ const char *options,
+ uid_t uid_shift,
+ const char *selinux_apifs_context,
+ char **ret) {
+
+ char *buf = NULL;
+
+ if (uid_shift != UID_INVALID) {
+ if (asprintf(&buf, "%s%suid=" UID_FMT ",gid=" UID_FMT,
+ strempty(options), options ? "," : "",
+ uid_shift, uid_shift) < 0)
+ return -ENOMEM;
+
+ options = buf;
+ }
+
+#if HAVE_SELINUX
+ if (selinux_apifs_context) {
+ char *t;
+
+ t = strjoin(strempty(options), options ? "," : "",
+ "context=\"", selinux_apifs_context, "\"");
+ free(buf);
+ if (!t)
+ return -ENOMEM;
+
+ buf = t;
+ }
+#endif
+
+ if (!buf && options) {
+ buf = strdup(options);
+ if (!buf)
+ return -ENOMEM;
+ }
+ *ret = buf;
+
+ return !!buf;
+}
+
+int mount_sysfs(const char *dest, MountSettingsMask mount_settings) {
+ const char *full, *top, *x;
+ int r;
+ unsigned long extra_flags = 0;
+
+ top = prefix_roota(dest, "/sys");
+ r = path_is_fs_type(top, SYSFS_MAGIC);
+ if (r < 0)
+ return log_error_errno(r, "Failed to determine filesystem type of %s: %m", top);
+ /* /sys might already be mounted as sysfs by the outer child in the
+ * !netns case. In this case, it's all good. Don't touch it because we
+ * don't have the right to do so, see https://github.com/systemd/systemd/issues/1555.
+ */
+ if (r > 0)
+ return 0;
+
+ full = prefix_roota(top, "/full");
+
+ (void) mkdir(full, 0755);
+
+ if (mount_settings & MOUNT_APPLY_APIVFS_RO)
+ extra_flags |= MS_RDONLY;
+
+ r = mount_verbose(LOG_ERR, "sysfs", full, "sysfs",
+ MS_NOSUID|MS_NOEXEC|MS_NODEV|extra_flags, NULL);
+ if (r < 0)
+ return r;
+
+ FOREACH_STRING(x, "block", "bus", "class", "dev", "devices", "kernel") {
+ _cleanup_free_ char *from = NULL, *to = NULL;
+
+ from = prefix_root(full, x);
+ if (!from)
+ return log_oom();
+
+ to = prefix_root(top, x);
+ if (!to)
+ return log_oom();
+
+ (void) mkdir(to, 0755);
+
+ r = mount_verbose(LOG_ERR, from, to, NULL, MS_BIND, NULL);
+ if (r < 0)
+ return r;
+
+ r = mount_verbose(LOG_ERR, NULL, to, NULL,
+ MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT|extra_flags, NULL);
+ if (r < 0)
+ return r;
+ }
+
+ r = umount_verbose(full);
+ if (r < 0)
+ return r;
+
+ if (rmdir(full) < 0)
+ return log_error_errno(errno, "Failed to remove %s: %m", full);
+
+ /* Create mountpoint for cgroups. Otherwise we are not allowed since we
+ * remount /sys read-only.
+ */
+ x = prefix_roota(top, "/fs/cgroup");
+ (void) mkdir_p(x, 0755);
+
+ return mount_verbose(LOG_ERR, NULL, top, NULL,
+ MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT|extra_flags, NULL);
+}
+
+static int mkdir_userns(const char *path, mode_t mode, uid_t uid_shift) {
+ int r;
+
+ assert(path);
+
+ r = mkdir_errno_wrapper(path, mode);
+ if (r < 0 && r != -EEXIST)
+ return r;
+
+ if (uid_shift == UID_INVALID)
+ return 0;
+
+ if (lchown(path, uid_shift, uid_shift) < 0)
+ return -errno;
+
+ return 0;
+}
+
+static int mkdir_userns_p(const char *prefix, const char *path, mode_t mode, uid_t uid_shift) {
+ const char *p, *e;
+ int r;
+
+ assert(path);
+
+ if (prefix && !path_startswith(path, prefix))
+ return -ENOTDIR;
+
+ /* create every parent directory in the path, except the last component */
+ p = path + strspn(path, "/");
+ for (;;) {
+ char t[strlen(path) + 1];
+
+ e = p + strcspn(p, "/");
+ p = e + strspn(e, "/");
+
+ /* Is this the last component? If so, then we're done */
+ if (*p == 0)
+ break;
+
+ memcpy(t, path, e - path);
+ t[e-path] = 0;
+
+ if (prefix && path_startswith(prefix, t))
+ continue;
+
+ r = mkdir_userns(t, mode, uid_shift);
+ if (r < 0)
+ return r;
+ }
+
+ return mkdir_userns(path, mode, uid_shift);
+}
+
+int mount_all(const char *dest,
+ MountSettingsMask mount_settings,
+ uid_t uid_shift,
+ const char *selinux_apifs_context) {
+
+#define PROC_INACCESSIBLE(path) \
+ { NULL, (path), NULL, NULL, MS_BIND, \
+ MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO|MOUNT_INACCESSIBLE_REG }, /* Bind mount first ... */ \
+ { NULL, (path), NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, \
+ MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO } /* Then, make it r/o */
+
+#define PROC_READ_ONLY(path) \
+ { (path), (path), NULL, NULL, MS_BIND, \
+ MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO }, /* Bind mount first ... */ \
+ { NULL, (path), NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, \
+ MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO } /* Then, make it r/o */
+
+ typedef struct MountPoint {
+ const char *what;
+ const char *where;
+ const char *type;
+ const char *options;
+ unsigned long flags;
+ MountSettingsMask mount_settings;
+ } MountPoint;
+
+ static const MountPoint mount_table[] = {
+ /* First we list inner child mounts (i.e. mounts applied *after* entering user namespacing) */
+ { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ MOUNT_FATAL|MOUNT_IN_USERNS },
+
+ { "/proc/sys", "/proc/sys", NULL, NULL, MS_BIND,
+ MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO }, /* Bind mount first ... */
+
+ { "/proc/sys/net", "/proc/sys/net", NULL, NULL, MS_BIND,
+ MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO|MOUNT_APPLY_APIVFS_NETNS }, /* (except for this) */
+
+ { NULL, "/proc/sys", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT,
+ MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO }, /* ... then, make it r/o */
+
+ /* Make these files inaccessible to container payloads: they potentially leak information about kernel
+ * internals or the host's execution environment to the container */
+ PROC_INACCESSIBLE("/proc/kallsyms"),
+ PROC_INACCESSIBLE("/proc/kcore"),
+ PROC_INACCESSIBLE("/proc/keys"),
+ PROC_INACCESSIBLE("/proc/sysrq-trigger"),
+ PROC_INACCESSIBLE("/proc/timer_list"),
+
+ /* Make these directories read-only to container payloads: they show hardware information, and in some
+ * cases contain tunables the container really shouldn't have access to. */
+ PROC_READ_ONLY("/proc/acpi"),
+ PROC_READ_ONLY("/proc/apm"),
+ PROC_READ_ONLY("/proc/asound"),
+ PROC_READ_ONLY("/proc/bus"),
+ PROC_READ_ONLY("/proc/fs"),
+ PROC_READ_ONLY("/proc/irq"),
+ PROC_READ_ONLY("/proc/scsi"),
+
+ /* Then we list outer child mounts (i.e. mounts applied *before* entering user namespacing) */
+ { "tmpfs", "/tmp", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME,
+ MOUNT_FATAL|MOUNT_APPLY_TMPFS_TMP },
+ { "tmpfs", "/sys", "tmpfs", "mode=555", MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ MOUNT_FATAL|MOUNT_APPLY_APIVFS_NETNS },
+ { "sysfs", "/sys", "sysfs", NULL, MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ MOUNT_FATAL|MOUNT_APPLY_APIVFS_RO }, /* skipped if above was mounted */
+ { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
+ MOUNT_FATAL }, /* skipped if above was mounted */
+ { "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME,
+ MOUNT_FATAL },
+ { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME,
+ MOUNT_FATAL },
+ { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME,
+ MOUNT_FATAL },
+ { "mqueue", "/dev/mqueue", "mqueue", NULL, 0,
+ MOUNT_FATAL },
+
+#if HAVE_SELINUX
+ { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND,
+ 0 }, /* Bind mount first */
+ { NULL, "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT,
+ 0 }, /* Then, make it r/o */
+#endif
+ };
+
+ _cleanup_(unlink_and_freep) char *inaccessible = NULL;
+ bool use_userns = (mount_settings & MOUNT_USE_USERNS);
+ bool netns = (mount_settings & MOUNT_APPLY_APIVFS_NETNS);
+ bool ro = (mount_settings & MOUNT_APPLY_APIVFS_RO);
+ bool in_userns = (mount_settings & MOUNT_IN_USERNS);
+ bool tmpfs_tmp = (mount_settings & MOUNT_APPLY_TMPFS_TMP);
+ size_t k;
+ int r;
+
+ for (k = 0; k < ELEMENTSOF(mount_table); k++) {
+ _cleanup_free_ char *where = NULL, *options = NULL;
+ const char *o, *what;
+ bool fatal = (mount_table[k].mount_settings & MOUNT_FATAL);
+
+ if (in_userns != (bool)(mount_table[k].mount_settings & MOUNT_IN_USERNS))
+ continue;
+
+ if (!netns && (bool)(mount_table[k].mount_settings & MOUNT_APPLY_APIVFS_NETNS))
+ continue;
+
+ if (!ro && (bool)(mount_table[k].mount_settings & MOUNT_APPLY_APIVFS_RO))
+ continue;
+
+ if (!tmpfs_tmp && (bool)(mount_table[k].mount_settings & MOUNT_APPLY_TMPFS_TMP))
+ continue;
+
+ r = chase_symlinks(mount_table[k].where, dest, CHASE_NONEXISTENT|CHASE_PREFIX_ROOT, &where);
+ if (r < 0)
+ return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, mount_table[k].where);
+
+ if (mount_table[k].mount_settings & MOUNT_INACCESSIBLE_REG) {
+
+ if (!inaccessible) {
+ _cleanup_free_ char *np = NULL;
+
+ r = tempfn_random_child(NULL, "inaccessible", &np);
+ if (r < 0)
+ return log_error_errno(r, "Failed to generate inaccessible file node path: %m");
+
+ r = touch_file(np, false, USEC_INFINITY, UID_INVALID, GID_INVALID, 0000);
+ if (r < 0)
+ return log_error_errno(r, "Failed to create inaccessible file node '%s': %m", np);
+
+ inaccessible = TAKE_PTR(np);
+ }
+
+ what = inaccessible;
+ } else
+ what = mount_table[k].what;
+
+ r = path_is_mount_point(where, NULL, 0);
+ if (r < 0 && r != -ENOENT)
+ return log_error_errno(r, "Failed to detect whether %s is a mount point: %m", where);
+
+ /* Skip this entry if it is not a remount. */
+ if (what && r > 0)
+ continue;
+
+ r = mkdir_userns_p(dest, where, 0755, (use_userns && !in_userns) ? uid_shift : UID_INVALID);
+ if (r < 0 && r != -EEXIST) {
+ if (fatal && r != -EROFS)
+ return log_error_errno(r, "Failed to create directory %s: %m", where);
+
+ log_debug_errno(r, "Failed to create directory %s: %m", where);
+ /* If we failed mkdir() or chown() due to the root
+ * directory being read only, attempt to mount this fs
+ * anyway and let mount_verbose log any errors */
+ if (r != -EROFS)
+ continue;
+ }
+
+ o = mount_table[k].options;
+ if (streq_ptr(mount_table[k].type, "tmpfs")) {
+ r = tmpfs_patch_options(o, in_userns ? 0 : uid_shift, selinux_apifs_context, &options);
+ if (r < 0)
+ return log_oom();
+ if (r > 0)
+ o = options;
+ }
+
+ r = mount_verbose(fatal ? LOG_ERR : LOG_DEBUG,
+ what,
+ where,
+ mount_table[k].type,
+ mount_table[k].flags,
+ o);
+ if (r < 0 && fatal)
+ return r;
+ }
+
+ return 0;
+}
+
+static int mount_bind(const char *dest, CustomMount *m) {
+
+ _cleanup_free_ char *where = NULL;
+ struct stat source_st, dest_st;
+ int r;
+
+ assert(dest);
+ assert(m);
+
+ if (stat(m->source, &source_st) < 0)
+ return log_error_errno(errno, "Failed to stat %s: %m", m->source);
+
+ r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where);
+ if (r < 0)
+ return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
+ if (r > 0) { /* Path exists already? */
+
+ if (stat(where, &dest_st) < 0)
+ return log_error_errno(errno, "Failed to stat %s: %m", where);
+
+ if (S_ISDIR(source_st.st_mode) && !S_ISDIR(dest_st.st_mode))
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Cannot bind mount directory %s on file %s.",
+ m->source, where);
+
+ if (!S_ISDIR(source_st.st_mode) && S_ISDIR(dest_st.st_mode))
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Cannot bind mount file %s on directory %s.",
+ m->source, where);
+
+ } else { /* Path doesn't exist yet? */
+ r = mkdir_parents_label(where, 0755);
+ if (r < 0)
+ return log_error_errno(r, "Failed to make parents of %s: %m", where);
+
+ /* Create the mount point. Any non-directory file can be
+ * mounted on any non-directory file (regular, fifo, socket,
+ * char, block).
+ */
+ if (S_ISDIR(source_st.st_mode))
+ r = mkdir_label(where, 0755);
+ else
+ r = touch(where);
+ if (r < 0)
+ return log_error_errno(r, "Failed to create mount point %s: %m", where);
+
+ }
+
+ r = mount_verbose(LOG_ERR, m->source, where, NULL, MS_BIND | MS_REC, m->options);
+ if (r < 0)
+ return r;
+
+ if (m->read_only) {
+ r = bind_remount_recursive(where, true, NULL);
+ if (r < 0)
+ return log_error_errno(r, "Read-only bind mount failed: %m");
+ }
+
+ return 0;
+}
+
+static int mount_tmpfs(
+ const char *dest,
+ CustomMount *m,
+ bool userns, uid_t uid_shift, uid_t uid_range,
+ const char *selinux_apifs_context) {
+
+ const char *options;
+ _cleanup_free_ char *buf = NULL, *where = NULL;
+ int r;
+
+ assert(dest);
+ assert(m);
+
+ r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where);
+ if (r < 0)
+ return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
+ if (r == 0) { /* Doesn't exist yet? */
+ r = mkdir_p_label(where, 0755);
+ if (r < 0)
+ return log_error_errno(r, "Creating mount point for tmpfs %s failed: %m", where);
+ }
+
+ r = tmpfs_patch_options(m->options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf);
+ if (r < 0)
+ return log_oom();
+ options = r > 0 ? buf : m->options;
+
+ return mount_verbose(LOG_ERR, "tmpfs", where, "tmpfs", MS_NODEV|MS_STRICTATIME, options);
+}
+
+static char *joined_and_escaped_lower_dirs(char **lower) {
+ _cleanup_strv_free_ char **sv = NULL;
+
+ sv = strv_copy(lower);
+ if (!sv)
+ return NULL;
+
+ strv_reverse(sv);
+
+ if (!strv_shell_escape(sv, ",:"))
+ return NULL;
+
+ return strv_join(sv, ":");
+}
+
+static int mount_overlay(const char *dest, CustomMount *m) {
+
+ _cleanup_free_ char *lower = NULL, *where = NULL, *escaped_source = NULL;
+ const char *options;
+ int r;
+
+ assert(dest);
+ assert(m);
+
+ r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where);
+ if (r < 0)
+ return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
+ if (r == 0) { /* Doesn't exist yet? */
+ r = mkdir_label(where, 0755);
+ if (r < 0)
+ return log_error_errno(r, "Creating mount point for overlay %s failed: %m", where);
+ }
+
+ (void) mkdir_p_label(m->source, 0755);
+
+ lower = joined_and_escaped_lower_dirs(m->lower);
+ if (!lower)
+ return log_oom();
+
+ escaped_source = shell_escape(m->source, ",:");
+ if (!escaped_source)
+ return log_oom();
+
+ if (m->read_only)
+ options = strjoina("lowerdir=", escaped_source, ":", lower);
+ else {
+ _cleanup_free_ char *escaped_work_dir = NULL;
+
+ escaped_work_dir = shell_escape(m->work_dir, ",:");
+ if (!escaped_work_dir)
+ return log_oom();
+
+ options = strjoina("lowerdir=", lower, ",upperdir=", escaped_source, ",workdir=", escaped_work_dir);
+ }
+
+ return mount_verbose(LOG_ERR, "overlay", where, "overlay", m->read_only ? MS_RDONLY : 0, options);
+}
+
+int mount_custom(
+ const char *dest,
+ CustomMount *mounts, size_t n,
+ bool userns, uid_t uid_shift, uid_t uid_range,
+ const char *selinux_apifs_context) {
+
+ size_t i;
+ int r;
+
+ assert(dest);
+
+ for (i = 0; i < n; i++) {
+ CustomMount *m = mounts + i;
+
+ switch (m->type) {
+
+ case CUSTOM_MOUNT_BIND:
+ r = mount_bind(dest, m);
+ break;
+
+ case CUSTOM_MOUNT_TMPFS:
+ r = mount_tmpfs(dest, m, userns, uid_shift, uid_range, selinux_apifs_context);
+ break;
+
+ case CUSTOM_MOUNT_OVERLAY:
+ r = mount_overlay(dest, m);
+ break;
+
+ default:
+ assert_not_reached("Unknown custom mount type");
+ }
+
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int setup_volatile_state(
+ const char *directory,
+ VolatileMode mode,
+ bool userns, uid_t uid_shift, uid_t uid_range,
+ const char *selinux_apifs_context) {
+
+ _cleanup_free_ char *buf = NULL;
+ const char *p, *options;
+ int r;
+
+ assert(directory);
+
+ if (mode != VOLATILE_STATE)
+ return 0;
+
+ /* --volatile=state means we simply overmount /var
+ with a tmpfs, and the rest read-only. */
+
+ r = bind_remount_recursive(directory, true, NULL);
+ if (r < 0)
+ return log_error_errno(r, "Failed to remount %s read-only: %m", directory);
+
+ p = prefix_roota(directory, "/var");
+ r = mkdir(p, 0755);
+ if (r < 0 && errno != EEXIST)
+ return log_error_errno(errno, "Failed to create %s: %m", directory);
+
+ options = "mode=755";
+ r = tmpfs_patch_options(options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf);
+ if (r < 0)
+ return log_oom();
+ if (r > 0)
+ options = buf;
+
+ return mount_verbose(LOG_ERR, "tmpfs", p, "tmpfs", MS_STRICTATIME, options);
+}
+
+int setup_volatile(
+ const char *directory,
+ VolatileMode mode,
+ bool userns, uid_t uid_shift, uid_t uid_range,
+ const char *selinux_apifs_context) {
+
+ bool tmpfs_mounted = false, bind_mounted = false;
+ char template[] = "/tmp/nspawn-volatile-XXXXXX";
+ _cleanup_free_ char *buf = NULL;
+ const char *f, *t, *options;
+ int r;
+
+ assert(directory);
+
+ if (mode != VOLATILE_YES)
+ return 0;
+
+ /* --volatile=yes means we mount a tmpfs to the root dir, and
+ the original /usr to use inside it, and that read-only. */
+
+ if (!mkdtemp(template))
+ return log_error_errno(errno, "Failed to create temporary directory: %m");
+
+ options = "mode=755";
+ r = tmpfs_patch_options(options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf);
+ if (r < 0)
+ return log_oom();
+ if (r > 0)
+ options = buf;
+
+ r = mount_verbose(LOG_ERR, "tmpfs", template, "tmpfs", MS_STRICTATIME, options);
+ if (r < 0)
+ goto fail;
+
+ tmpfs_mounted = true;
+
+ f = prefix_roota(directory, "/usr");
+ t = prefix_roota(template, "/usr");
+
+ r = mkdir(t, 0755);
+ if (r < 0 && errno != EEXIST) {
+ r = log_error_errno(errno, "Failed to create %s: %m", t);
+ goto fail;
+ }
+
+ r = mount_verbose(LOG_ERR, f, t, NULL, MS_BIND|MS_REC, NULL);
+ if (r < 0)
+ goto fail;
+
+ bind_mounted = true;
+
+ r = bind_remount_recursive(t, true, NULL);
+ if (r < 0) {
+ log_error_errno(r, "Failed to remount %s read-only: %m", t);
+ goto fail;
+ }
+
+ r = mount_verbose(LOG_ERR, template, directory, NULL, MS_MOVE, NULL);
+ if (r < 0)
+ goto fail;
+
+ (void) rmdir(template);
+
+ return 0;
+
+fail:
+ if (bind_mounted)
+ (void) umount_verbose(t);
+
+ if (tmpfs_mounted)
+ (void) umount_verbose(template);
+ (void) rmdir(template);
+ return r;
+}
+
+/* Expects *pivot_root_new and *pivot_root_old to be initialised to allocated memory or NULL. */
+int pivot_root_parse(char **pivot_root_new, char **pivot_root_old, const char *s) {
+ _cleanup_free_ char *root_new = NULL, *root_old = NULL;
+ const char *p = s;
+ int r;
+
+ assert(pivot_root_new);
+ assert(pivot_root_old);
+
+ r = extract_first_word(&p, &root_new, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -EINVAL;
+
+ if (isempty(p))
+ root_old = NULL;
+ else {
+ root_old = strdup(p);
+ if (!root_old)
+ return -ENOMEM;
+ }
+
+ if (!path_is_absolute(root_new))
+ return -EINVAL;
+ if (root_old && !path_is_absolute(root_old))
+ return -EINVAL;
+
+ free_and_replace(*pivot_root_new, root_new);
+ free_and_replace(*pivot_root_old, root_old);
+
+ return 0;
+}
+
+int setup_pivot_root(const char *directory, const char *pivot_root_new, const char *pivot_root_old) {
+ _cleanup_free_ char *directory_pivot_root_new = NULL;
+ _cleanup_free_ char *pivot_tmp_pivot_root_old = NULL;
+ char pivot_tmp[] = "/tmp/nspawn-pivot-XXXXXX";
+ bool remove_pivot_tmp = false;
+ int r;
+
+ assert(directory);
+
+ if (!pivot_root_new)
+ return 0;
+
+ /* Pivot pivot_root_new to / and the existing / to pivot_root_old.
+ * If pivot_root_old is NULL, the existing / disappears.
+ * This requires a temporary directory, pivot_tmp, which is
+ * not a child of either.
+ *
+ * This is typically used for OSTree-style containers, where
+ * the root partition contains several sysroots which could be
+ * run. Normally, one would be chosen by the bootloader and
+ * pivoted to / by initramfs.
+ *
+ * For example, for an OSTree deployment, pivot_root_new
+ * would be: /ostree/deploy/$os/deploy/$checksum. Note that this
+ * code doesn’t do the /var mount which OSTree expects: use
+ * --bind +/sysroot/ostree/deploy/$os/var:/var for that.
+ *
+ * So in the OSTree case, we’ll end up with something like:
+ * - directory = /tmp/nspawn-root-123456
+ * - pivot_root_new = /ostree/deploy/os/deploy/123abc
+ * - pivot_root_old = /sysroot
+ * - directory_pivot_root_new =
+ * /tmp/nspawn-root-123456/ostree/deploy/os/deploy/123abc
+ * - pivot_tmp = /tmp/nspawn-pivot-123456
+ * - pivot_tmp_pivot_root_old = /tmp/nspawn-pivot-123456/sysroot
+ *
+ * Requires all file systems at directory and below to be mounted
+ * MS_PRIVATE or MS_SLAVE so they can be moved.
+ */
+ directory_pivot_root_new = prefix_root(directory, pivot_root_new);
+
+ /* Remount directory_pivot_root_new to make it movable. */
+ r = mount_verbose(LOG_ERR, directory_pivot_root_new, directory_pivot_root_new, NULL, MS_BIND, NULL);
+ if (r < 0)
+ goto done;
+
+ if (pivot_root_old) {
+ if (!mkdtemp(pivot_tmp)) {
+ r = log_error_errno(errno, "Failed to create temporary directory: %m");
+ goto done;
+ }
+
+ remove_pivot_tmp = true;
+ pivot_tmp_pivot_root_old = prefix_root(pivot_tmp, pivot_root_old);
+
+ r = mount_verbose(LOG_ERR, directory_pivot_root_new, pivot_tmp, NULL, MS_MOVE, NULL);
+ if (r < 0)
+ goto done;
+
+ r = mount_verbose(LOG_ERR, directory, pivot_tmp_pivot_root_old, NULL, MS_MOVE, NULL);
+ if (r < 0)
+ goto done;
+
+ r = mount_verbose(LOG_ERR, pivot_tmp, directory, NULL, MS_MOVE, NULL);
+ if (r < 0)
+ goto done;
+ } else {
+ r = mount_verbose(LOG_ERR, directory_pivot_root_new, directory, NULL, MS_MOVE, NULL);
+ if (r < 0)
+ goto done;
+ }
+
+done:
+ if (remove_pivot_tmp)
+ (void) rmdir(pivot_tmp);
+
+ return r;
+}