| /* 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 "fileio.h" |
| #include "fs-util.h" |
| #include "label.h" |
| #include "mkdir.h" |
| #include "mount-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 "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 void *a, const void *b) { |
| const CustomMount *x = a, *y = b; |
| int r; |
| |
| r = path_compare(x->destination, y->destination); |
| if (r != 0) |
| return r; |
| |
| if (x->type < y->type) |
| return -1; |
| if (x->type > y->type) |
| return 1; |
| |
| return 0; |
| } |
| |
| 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 */ |
| qsort_safe(l, n, sizeof(CustomMount), 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; |
| } |
| |
| static int tmpfs_patch_options( |
| const char *options, |
| bool userns, |
| uid_t uid_shift, uid_t uid_range, |
| bool patch_ids, |
| const char *selinux_apifs_context, |
| char **ret) { |
| |
| char *buf = NULL; |
| |
| if ((userns && uid_shift != 0) || patch_ids) { |
| assert(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. |
| */ |
| if (cg_ns_supported()) { |
| 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, MountSettingsMask mask, uid_t uid_shift) { |
| int r; |
| |
| assert(path); |
| |
| r = mkdir_errno_wrapper(path, mode); |
| if (r < 0 && r != -EEXIST) |
| return r; |
| |
| if ((mask & MOUNT_USE_USERNS) == 0) |
| return 0; |
| |
| if (mask & MOUNT_IN_USERNS) |
| 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, MountSettingsMask mask, 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, mask, uid_shift); |
| if (r < 0) |
| return r; |
| } |
| |
| return mkdir_userns(path, mode, mask, uid_shift); |
| } |
| |
| int mount_all(const char *dest, |
| MountSettingsMask mount_settings, |
| uid_t uid_shift, uid_t uid_range, |
| 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 }, |
| { "tmpfs", "/sys", "tmpfs", "mode=755", 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 }, |
| |
| #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); |
| 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; |
| |
| 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, mount_settings, uid_shift); |
| 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")) { |
| if (in_userns) |
| r = tmpfs_patch_options(o, use_userns, 0, uid_range, true, selinux_apifs_context, &options); |
| else |
| r = tmpfs_patch_options(o, use_userns, uid_shift, uid_range, false, 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)) { |
| log_error("Cannot bind mount directory %s on file %s.", m->source, where); |
| return -EINVAL; |
| } |
| |
| if (!S_ISDIR(source_st.st_mode) && S_ISDIR(dest_st.st_mode)) { |
| log_error("Cannot bind mount file %s on directory %s.", m->source, where); |
| return -EINVAL; |
| } |
| |
| } 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, userns, uid_shift, uid_range, false, 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; |
| } |
| |
| /* Retrieve existing subsystems. This function is called in a new cgroup |
| * namespace. |
| */ |
| static int get_process_controllers(Set **ret) { |
| _cleanup_set_free_free_ Set *controllers = NULL; |
| _cleanup_fclose_ FILE *f = NULL; |
| int r; |
| |
| assert(ret); |
| |
| controllers = set_new(&string_hash_ops); |
| if (!controllers) |
| return -ENOMEM; |
| |
| f = fopen("/proc/self/cgroup", "re"); |
| if (!f) |
| return errno == ENOENT ? -ESRCH : -errno; |
| |
| for (;;) { |
| _cleanup_free_ char *line = NULL; |
| char *e, *l; |
| |
| r = read_line(f, LONG_LINE_MAX, &line); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| break; |
| |
| l = strchr(line, ':'); |
| if (!l) |
| continue; |
| |
| l++; |
| e = strchr(l, ':'); |
| if (!e) |
| continue; |
| |
| *e = 0; |
| |
| if (STR_IN_SET(l, "", "name=systemd", "name=unified")) |
| continue; |
| |
| r = set_put_strdup(controllers, l); |
| if (r < 0) |
| return r; |
| } |
| |
| *ret = TAKE_PTR(controllers); |
| |
| return 0; |
| } |
| |
| static int mount_legacy_cgroup_hierarchy( |
| const char *dest, |
| const char *controller, |
| const char *hierarchy, |
| bool read_only) { |
| |
| const char *to, *fstype, *opts; |
| int r; |
| |
| to = strjoina(strempty(dest), "/sys/fs/cgroup/", hierarchy); |
| |
| r = path_is_mount_point(to, dest, 0); |
| if (r < 0 && r != -ENOENT) |
| return log_error_errno(r, "Failed to determine if %s is mounted already: %m", to); |
| if (r > 0) |
| return 0; |
| |
| mkdir_p(to, 0755); |
| |
| /* The superblock mount options of the mount point need to be |
| * identical to the hosts', and hence writable... */ |
| if (streq(controller, SYSTEMD_CGROUP_CONTROLLER_HYBRID)) { |
| fstype = "cgroup2"; |
| opts = NULL; |
| } else if (streq(controller, SYSTEMD_CGROUP_CONTROLLER_LEGACY)) { |
| fstype = "cgroup"; |
| opts = "none,name=systemd,xattr"; |
| } else { |
| fstype = "cgroup"; |
| opts = controller; |
| } |
| |
| r = mount_verbose(LOG_ERR, "cgroup", to, fstype, MS_NOSUID|MS_NOEXEC|MS_NODEV, opts); |
| if (r < 0) |
| return r; |
| |
| /* ... hence let's only make the bind mount read-only, not the superblock. */ |
| if (read_only) { |
| r = mount_verbose(LOG_ERR, NULL, to, NULL, |
| MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL); |
| if (r < 0) |
| return r; |
| } |
| |
| return 1; |
| } |
| |
| /* Mount a legacy cgroup hierarchy when cgroup namespaces are supported. */ |
| static int mount_legacy_cgns_supported( |
| const char *dest, |
| CGroupUnified unified_requested, |
| bool userns, |
| uid_t uid_shift, |
| uid_t uid_range, |
| const char *selinux_apifs_context) { |
| |
| _cleanup_set_free_free_ Set *controllers = NULL; |
| const char *cgroup_root = "/sys/fs/cgroup", *c; |
| int r; |
| |
| (void) mkdir_p(cgroup_root, 0755); |
| |
| /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */ |
| r = path_is_mount_point(cgroup_root, dest, AT_SYMLINK_FOLLOW); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m"); |
| if (r == 0) { |
| _cleanup_free_ char *options = NULL; |
| |
| /* When cgroup namespaces are enabled and user namespaces are |
| * used then the mount of the cgroupfs is done *inside* the new |
| * user namespace. We're root in the new user namespace and the |
| * kernel will happily translate our uid/gid to the correct |
| * uid/gid as seen from e.g. /proc/1/mountinfo. So we simply |
| * pass uid 0 and not uid_shift to tmpfs_patch_options(). |
| */ |
| r = tmpfs_patch_options("mode=755", userns, 0, uid_range, true, selinux_apifs_context, &options); |
| if (r < 0) |
| return log_oom(); |
| |
| r = mount_verbose(LOG_ERR, "tmpfs", cgroup_root, "tmpfs", |
| MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options); |
| if (r < 0) |
| return r; |
| } |
| |
| r = cg_all_unified(); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| goto skip_controllers; |
| |
| r = get_process_controllers(&controllers); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine cgroup controllers: %m"); |
| |
| for (;;) { |
| _cleanup_free_ const char *controller = NULL; |
| |
| controller = set_steal_first(controllers); |
| if (!controller) |
| break; |
| |
| r = mount_legacy_cgroup_hierarchy("", controller, controller, !userns); |
| if (r < 0) |
| return r; |
| |
| /* When multiple hierarchies are co-mounted, make their |
| * constituting individual hierarchies a symlink to the |
| * co-mount. |
| */ |
| c = controller; |
| for (;;) { |
| _cleanup_free_ char *target = NULL, *tok = NULL; |
| |
| r = extract_first_word(&c, &tok, ",", 0); |
| if (r < 0) |
| return log_error_errno(r, "Failed to extract co-mounted cgroup controller: %m"); |
| if (r == 0) |
| break; |
| |
| if (streq(controller, tok)) |
| break; |
| |
| target = prefix_root("/sys/fs/cgroup/", tok); |
| if (!target) |
| return log_oom(); |
| |
| r = symlink_idempotent(controller, target); |
| if (r == -EINVAL) |
| return log_error_errno(r, "Invalid existing symlink for combined hierarchy: %m"); |
| if (r < 0) |
| return log_error_errno(r, "Failed to create symlink for combined hierarchy: %m"); |
| } |
| } |
| |
| skip_controllers: |
| if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) { |
| r = mount_legacy_cgroup_hierarchy("", SYSTEMD_CGROUP_CONTROLLER_HYBRID, "unified", false); |
| if (r < 0) |
| return r; |
| } |
| |
| r = mount_legacy_cgroup_hierarchy("", SYSTEMD_CGROUP_CONTROLLER_LEGACY, "systemd", false); |
| if (r < 0) |
| return r; |
| |
| if (!userns) |
| return mount_verbose(LOG_ERR, NULL, cgroup_root, NULL, |
| MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755"); |
| |
| return 0; |
| } |
| |
| /* Mount legacy cgroup hierarchy when cgroup namespaces are unsupported. */ |
| static int mount_legacy_cgns_unsupported( |
| const char *dest, |
| CGroupUnified unified_requested, |
| bool userns, |
| uid_t uid_shift, |
| uid_t uid_range, |
| const char *selinux_apifs_context) { |
| |
| _cleanup_set_free_free_ Set *controllers = NULL; |
| const char *cgroup_root; |
| int r; |
| |
| cgroup_root = prefix_roota(dest, "/sys/fs/cgroup"); |
| |
| (void) mkdir_p(cgroup_root, 0755); |
| |
| /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */ |
| r = path_is_mount_point(cgroup_root, dest, AT_SYMLINK_FOLLOW); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m"); |
| if (r == 0) { |
| _cleanup_free_ char *options = NULL; |
| |
| r = tmpfs_patch_options("mode=755", userns, uid_shift, uid_range, false, selinux_apifs_context, &options); |
| if (r < 0) |
| return log_oom(); |
| |
| r = mount_verbose(LOG_ERR, "tmpfs", cgroup_root, "tmpfs", |
| MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options); |
| if (r < 0) |
| return r; |
| } |
| |
| r = cg_all_unified(); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| goto skip_controllers; |
| |
| r = cg_kernel_controllers(&controllers); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine cgroup controllers: %m"); |
| |
| for (;;) { |
| _cleanup_free_ char *controller = NULL, *origin = NULL, *combined = NULL; |
| |
| controller = set_steal_first(controllers); |
| if (!controller) |
| break; |
| |
| origin = prefix_root("/sys/fs/cgroup/", controller); |
| if (!origin) |
| return log_oom(); |
| |
| r = readlink_malloc(origin, &combined); |
| if (r == -EINVAL) { |
| /* Not a symbolic link, but directly a single cgroup hierarchy */ |
| |
| r = mount_legacy_cgroup_hierarchy(dest, controller, controller, true); |
| if (r < 0) |
| return r; |
| |
| } else if (r < 0) |
| return log_error_errno(r, "Failed to read link %s: %m", origin); |
| else { |
| _cleanup_free_ char *target = NULL; |
| |
| target = prefix_root(dest, origin); |
| if (!target) |
| return log_oom(); |
| |
| /* A symbolic link, a combination of controllers in one hierarchy */ |
| |
| if (!filename_is_valid(combined)) { |
| log_warning("Ignoring invalid combined hierarchy %s.", combined); |
| continue; |
| } |
| |
| r = mount_legacy_cgroup_hierarchy(dest, combined, combined, true); |
| if (r < 0) |
| return r; |
| |
| r = symlink_idempotent(combined, target); |
| if (r == -EINVAL) |
| return log_error_errno(r, "Invalid existing symlink for combined hierarchy: %m"); |
| if (r < 0) |
| return log_error_errno(r, "Failed to create symlink for combined hierarchy: %m"); |
| } |
| } |
| |
| skip_controllers: |
| if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) { |
| r = mount_legacy_cgroup_hierarchy(dest, SYSTEMD_CGROUP_CONTROLLER_HYBRID, "unified", false); |
| if (r < 0) |
| return r; |
| } |
| |
| r = mount_legacy_cgroup_hierarchy(dest, SYSTEMD_CGROUP_CONTROLLER_LEGACY, "systemd", false); |
| if (r < 0) |
| return r; |
| |
| return mount_verbose(LOG_ERR, NULL, cgroup_root, NULL, |
| MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755"); |
| } |
| |
| static int mount_unified_cgroups(const char *dest) { |
| const char *p; |
| int r; |
| |
| assert(dest); |
| |
| p = prefix_roota(dest, "/sys/fs/cgroup"); |
| |
| (void) mkdir_p(p, 0755); |
| |
| r = path_is_mount_point(p, dest, AT_SYMLINK_FOLLOW); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine if %s is mounted already: %m", p); |
| if (r > 0) { |
| p = prefix_roota(dest, "/sys/fs/cgroup/cgroup.procs"); |
| if (access(p, F_OK) >= 0) |
| return 0; |
| if (errno != ENOENT) |
| return log_error_errno(errno, "Failed to determine if mount point %s contains the unified cgroup hierarchy: %m", p); |
| |
| log_error("%s is already mounted but not a unified cgroup hierarchy. Refusing.", p); |
| return -EINVAL; |
| } |
| |
| return mount_verbose(LOG_ERR, "cgroup", p, "cgroup2", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL); |
| } |
| |
| int mount_cgroups( |
| const char *dest, |
| CGroupUnified unified_requested, |
| bool userns, |
| uid_t uid_shift, |
| uid_t uid_range, |
| const char *selinux_apifs_context, |
| bool use_cgns) { |
| |
| if (unified_requested >= CGROUP_UNIFIED_ALL) |
| return mount_unified_cgroups(dest); |
| if (use_cgns) |
| return mount_legacy_cgns_supported(dest, unified_requested, userns, uid_shift, uid_range, selinux_apifs_context); |
| |
| return mount_legacy_cgns_unsupported(dest, unified_requested, userns, uid_shift, uid_range, selinux_apifs_context); |
| } |
| |
| static int mount_systemd_cgroup_writable_one(const char *root, const char *own) { |
| int r; |
| |
| assert(root); |
| assert(own); |
| |
| /* Make our own cgroup a (writable) bind mount */ |
| r = mount_verbose(LOG_ERR, own, own, NULL, MS_BIND, NULL); |
| if (r < 0) |
| return r; |
| |
| /* And then remount the systemd cgroup root read-only */ |
| return mount_verbose(LOG_ERR, NULL, root, NULL, |
| MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL); |
| } |
| |
| int mount_systemd_cgroup_writable( |
| const char *dest, |
| CGroupUnified unified_requested) { |
| |
| _cleanup_free_ char *own_cgroup_path = NULL; |
| const char *root, *own; |
| int r; |
| |
| assert(dest); |
| |
| r = cg_pid_get_path(NULL, 0, &own_cgroup_path); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine our own cgroup path: %m"); |
| |
| /* If we are living in the top-level, then there's nothing to do... */ |
| if (path_equal(own_cgroup_path, "/")) |
| return 0; |
| |
| if (unified_requested >= CGROUP_UNIFIED_ALL) { |
| |
| root = prefix_roota(dest, "/sys/fs/cgroup"); |
| own = strjoina(root, own_cgroup_path); |
| |
| } else { |
| |
| if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) { |
| root = prefix_roota(dest, "/sys/fs/cgroup/unified"); |
| own = strjoina(root, own_cgroup_path); |
| |
| r = mount_systemd_cgroup_writable_one(root, own); |
| if (r < 0) |
| return r; |
| } |
| |
| root = prefix_roota(dest, "/sys/fs/cgroup/systemd"); |
| own = strjoina(root, own_cgroup_path); |
| } |
| |
| return mount_systemd_cgroup_writable_one(root, own); |
| } |
| |
| 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, userns, uid_shift, uid_range, false, 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, userns, uid_shift, uid_range, false, 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; |
| } |