diff options
Diffstat (limited to 'src/nspawn/nspawn-mount.c')
| -rw-r--r-- | src/nspawn/nspawn-mount.c | 1406 |
1 files changed, 1406 insertions, 0 deletions
diff --git a/src/nspawn/nspawn-mount.c b/src/nspawn/nspawn-mount.c new file mode 100644 index 0000000..470f477 --- /dev/null +++ b/src/nspawn/nspawn-mount.c @@ -0,0 +1,1406 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <sys/mount.h> +#include <linux/magic.h> + +#include "alloc-util.h" +#include "chase.h" +#include "escape.h" +#include "fd-util.h" +#include "format-util.h" +#include "fs-util.h" +#include "label-util.h" +#include "mkdir-label.h" +#include "mount-util.h" +#include "mountpoint-util.h" +#include "namespace-util.h" +#include "nspawn-mount.h" +#include "parse-util.h" +#include "path-util.h" +#include "rm-rf.h" +#include "set.h" +#include "sort-util.h" +#include "stat-util.h" +#include "string-util.h" +#include "strv.h" +#include "tmpfile-util.h" +#include "user-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) { + for (size_t 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(m->type_argument); + } + + 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 int source_path_parse(const char *p, char **ret) { + assert(p); + assert(ret); + + if (isempty(p)) + return -EINVAL; + + if (*p == '+') { + if (!path_is_absolute(p + 1)) + return -EINVAL; + + char *s = strdup(p); + if (!s) + return -ENOMEM; + + *ret = TAKE_PTR(s); + return 0; + } + + return path_make_absolute_cwd(p, ret); +} + +static int source_path_parse_nullable(const char *p, char **ret) { + assert(p); + assert(ret); + + if (isempty(p)) { + *ret = NULL; + return 0; + } + + return source_path_parse(p, ret); +} + +static char *resolve_source_path(const char *dest, const char *source) { + if (!source) + return NULL; + + if (source[0] == '+') + return path_join(dest, source + 1); + + return strdup(source); +} + +static int allocate_temporary_source(CustomMount *m) { + assert(m); + assert(!m->source); + assert(!m->rm_rf_tmpdir); + + 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 = path_join(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); + + return 0; +} + +int custom_mount_prepare_all(const char *dest, CustomMount *l, size_t n) { + 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 (size_t i = 0; i < n; i++) { + CustomMount *m = l + i; + + /* /proc we mount in the inner child, i.e. when we acquired CLONE_NEWPID. All other mounts we mount + * already in the outer child, so that the mounts are already established before CLONE_NEWPID and in + * particular CLONE_NEWUSER. This also means any custom mounts below /proc also need to be mounted in + * the inner child, not the outer one. Determine this here. */ + m->in_userns = path_startswith(m->destination, "/proc"); + + if (m->type == CUSTOM_MOUNT_BIND) { + 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 */ + + r = allocate_temporary_source(m); + if (r < 0) + return r; + } + } + + if (m->type == CUSTOM_MOUNT_OVERLAY) { + 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->source) { + char *s; + + s = resolve_source_path(dest, m->source); + if (!s) + return log_oom(); + + free_and_replace(m->source, s); + } else { + r = allocate_temporary_source(m); + if (r < 0) + return r; + } + + 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 { + 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, *p = NULL; + CustomMount *m; + int r; + + assert(l); + assert(n); + + r = extract_many_words(&s, ":", 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(s)) { + opts = strdup(s); + if (!opts) + return -ENOMEM; + } + + r = source_path_parse_nullable(source, &p); + if (r < 0) + return r; + + if (!path_is_absolute(destination)) + return -EINVAL; + + m = custom_mount_add(l, n, CUSTOM_MOUNT_BIND); + if (!m) + return -ENOMEM; + + m->source = TAKE_PTR(p); + m->destination = TAKE_PTR(destination); + m->read_only = read_only; + m->options = TAKE_PTR(opts); + + return 0; +} + +int tmpfs_mount_parse(CustomMount **l, size_t *n, const char *s) { + _cleanup_free_ char *path = NULL, *opts = NULL; + const char *p = ASSERT_PTR(s); + CustomMount *m; + int r; + + assert(l); + assert(n); + + 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 r, k; + + k = strv_split_full(&lower, s, ":", EXTRACT_DONT_COALESCE_SEPARATORS); + if (k < 0) + return k; + if (k < 2) + return -EADDRNOTAVAIL; + if (k == 2) { + _cleanup_free_ char *p = NULL; + + /* 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. */ + + r = source_path_parse(lower[0], &p); + if (r < 0) + return r; + + free_and_replace(lower[0], p); + + r = source_path_parse(lower[1], &p); + if (r < 0) + return r; + + free_and_replace(lower[1], p); + + upper = TAKE_PTR(lower[1]); + + destination = strdup(upper[0] == '+' ? upper+1 : upper); /* take the destination without "+" prefix */ + if (!destination) + return -ENOMEM; + } else { + _cleanup_free_ char *p = NULL; + + /* 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) { + r = source_path_parse(*i, &p); + if (r < 0) + return r; + + free_and_replace(*i, p); + } + + /* If the upper directory is unspecified, then let's create it automatically as a throw-away directory + * in /var/tmp */ + r = source_path_parse_nullable(upper, &p); + if (r < 0) + return r; + + free_and_replace(upper, p); + + 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 inaccessible_mount_parse(CustomMount **l, size_t *n, const char *s) { + _cleanup_free_ char *path = NULL; + CustomMount *m; + + assert(l); + assert(n); + assert(s); + + if (!path_is_absolute(s)) + return -EINVAL; + + path = strdup(s); + if (!path) + return -ENOMEM; + + m = custom_mount_add(l, n, CUSTOM_MOUNT_INACCESSIBLE); + if (!m) + return -ENOMEM; + + m->destination = TAKE_PTR(path); + return 0; +} + +int tmpfs_patch_options( + const char *options, + uid_t uid_shift, + const char *selinux_apifs_context, + char **ret) { + + _cleanup_free_ char *buf = NULL; + + assert(ret); + + if (options) { + buf = strdup(options); + if (!buf) + return -ENOMEM; + } + + if (uid_shift != UID_INVALID) + if (strextendf_with_separator(&buf, ",", "uid=" UID_FMT ",gid=" UID_FMT, uid_shift, uid_shift) < 0) + return -ENOMEM; + +#if HAVE_SELINUX + if (selinux_apifs_context) + if (strextendf_with_separator(&buf, ",", "context=\"%s\"", selinux_apifs_context) < 0) + return -ENOMEM; +#endif + + *ret = TAKE_PTR(buf); + return !!*ret; +} + +int mount_sysfs(const char *dest, MountSettingsMask mount_settings) { + const char *full, *top; + 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 (FLAGS_SET(mount_settings, MOUNT_APPLY_APIVFS_RO)) + extra_flags |= MS_RDONLY; + + r = mount_nofollow_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 = path_join(full, x); + if (!from) + return log_oom(); + + to = path_join(top, x); + if (!to) + return log_oom(); + + (void) mkdir(to, 0755); + + r = mount_nofollow_verbose(LOG_ERR, from, to, NULL, MS_BIND, NULL); + if (r < 0) + return r; + + r = mount_nofollow_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(LOG_ERR, full, UMOUNT_NOFOLLOW); + 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. + */ + const char *x = prefix_roota(top, "/fs/cgroup"); + (void) mkdir_p(x, 0755); + + return mount_nofollow_verbose(LOG_ERR, NULL, top, NULL, + MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT|extra_flags, NULL); +} + +#define PROC_DEFAULT_MOUNT_FLAGS (MS_NOSUID|MS_NOEXEC|MS_NODEV) +#define SYS_DEFAULT_MOUNT_FLAGS (MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV) + +int mount_all(const char *dest, + MountSettingsMask mount_settings, + uid_t uid_shift, + const char *selinux_apifs_context) { + +#define PROC_INACCESSIBLE_REG(path) \ + { "/run/systemd/inaccessible/reg", (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 */ + +#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, PROC_DEFAULT_MOUNT_FLAGS, + MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_MKDIR|MOUNT_FOLLOW_SYMLINKS }, /* we follow symlinks here since not following them requires /proc/ already being mounted, which we don't have here. */ + + { "/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_REG("/proc/kallsyms"), + PROC_INACCESSIBLE_REG("/proc/kcore"), + PROC_INACCESSIBLE_REG("/proc/keys"), + PROC_INACCESSIBLE_REG("/proc/sysrq-trigger"), + PROC_INACCESSIBLE_REG("/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"), + + { "mqueue", "/dev/mqueue", "mqueue", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + MOUNT_IN_USERNS|MOUNT_MKDIR }, + + /* Then we list outer child mounts (i.e. mounts applied *before* entering user namespacing) */ + { "tmpfs", "/tmp", "tmpfs", "mode=01777" NESTED_TMPFS_LIMITS, MS_NOSUID|MS_NODEV|MS_STRICTATIME, + MOUNT_FATAL|MOUNT_APPLY_TMPFS_TMP|MOUNT_MKDIR }, + { "tmpfs", "/sys", "tmpfs", "mode=0555" TMPFS_LIMITS_SYS, MS_NOSUID|MS_NOEXEC|MS_NODEV, + MOUNT_FATAL|MOUNT_APPLY_APIVFS_NETNS|MOUNT_MKDIR }, + { "sysfs", "/sys", "sysfs", NULL, SYS_DEFAULT_MOUNT_FLAGS, + MOUNT_FATAL|MOUNT_APPLY_APIVFS_RO|MOUNT_MKDIR }, /* skipped if above was mounted */ + { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + MOUNT_FATAL|MOUNT_MKDIR }, /* skipped if above was mounted */ + { "tmpfs", "/dev", "tmpfs", "mode=0755" TMPFS_LIMITS_PRIVATE_DEV, MS_NOSUID|MS_STRICTATIME, + MOUNT_FATAL|MOUNT_MKDIR }, + { "tmpfs", "/dev/shm", "tmpfs", "mode=01777" NESTED_TMPFS_LIMITS, MS_NOSUID|MS_NODEV|MS_STRICTATIME, + MOUNT_FATAL|MOUNT_MKDIR }, + { "tmpfs", "/run", "tmpfs", "mode=0755" TMPFS_LIMITS_RUN, MS_NOSUID|MS_NODEV|MS_STRICTATIME, + MOUNT_FATAL|MOUNT_MKDIR }, + { "/run/host", "/run/host", NULL, NULL, MS_BIND, + MOUNT_FATAL|MOUNT_MKDIR|MOUNT_PREFIX_ROOT }, /* Prepare this so that we can make it read-only when we are done */ + { "/etc/os-release", "/run/host/os-release", NULL, NULL, MS_BIND, + MOUNT_TOUCH }, /* As per kernel interface requirements, bind mount first (creating mount points) and make read-only later */ + { "/usr/lib/os-release", "/run/host/os-release", NULL, NULL, MS_BIND, + MOUNT_FATAL }, /* If /etc/os-release doesn't exist use the version in /usr/lib as fallback */ + { NULL, "/run/host/os-release", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, + MOUNT_FATAL }, + { NULL, "/run/host/os-release", NULL, NULL, MS_PRIVATE, + MOUNT_FATAL }, /* Turn off propagation (we only want that for the mount propagation tunnel dir) */ + { NULL, "/run/host", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, + MOUNT_FATAL|MOUNT_IN_USERNS }, +#if HAVE_SELINUX + { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND, + MOUNT_MKDIR }, /* Bind mount first (mkdir/chown the mount point in case /sys/ is mounted as minimal skeleton tmpfs) */ + { NULL, "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, + 0 }, /* Then, make it r/o (don't mkdir/chown the mount point here, the previous entry already did that) */ + { NULL, "/sys/fs/selinux", NULL, NULL, MS_PRIVATE, + 0 }, /* Turn off propagation (we only want that for the mount propagation tunnel dir) */ +#endif + }; + + bool use_userns = FLAGS_SET(mount_settings, MOUNT_USE_USERNS); + bool netns = FLAGS_SET(mount_settings, MOUNT_APPLY_APIVFS_NETNS); + bool ro = FLAGS_SET(mount_settings, MOUNT_APPLY_APIVFS_RO); + bool in_userns = FLAGS_SET(mount_settings, MOUNT_IN_USERNS); + bool tmpfs_tmp = FLAGS_SET(mount_settings, MOUNT_APPLY_TMPFS_TMP); + int r; + + for (size_t k = 0; k < ELEMENTSOF(mount_table); k++) { + _cleanup_free_ char *where = NULL, *options = NULL, *prefixed = NULL; + bool fatal = FLAGS_SET(mount_table[k].mount_settings, MOUNT_FATAL); + const char *o; + + if (in_userns != FLAGS_SET(mount_table[k].mount_settings, MOUNT_IN_USERNS)) + continue; + + if (!netns && FLAGS_SET(mount_table[k].mount_settings, MOUNT_APPLY_APIVFS_NETNS)) + continue; + + if (!ro && FLAGS_SET(mount_table[k].mount_settings, MOUNT_APPLY_APIVFS_RO)) + continue; + + if (!tmpfs_tmp && FLAGS_SET(mount_table[k].mount_settings, MOUNT_APPLY_TMPFS_TMP)) + continue; + + r = chase(mount_table[k].where, dest, CHASE_NONEXISTENT|CHASE_PREFIX_ROOT, &where, NULL); + if (r < 0) + return log_error_errno(r, "Failed to resolve %s%s: %m", strempty(dest), mount_table[k].where); + + /* Skip this entry if it is not a remount. */ + if (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); + if (r > 0) + continue; + } + + if ((mount_table[k].mount_settings & (MOUNT_MKDIR|MOUNT_TOUCH)) != 0) { + uid_t u = (use_userns && !in_userns) ? uid_shift : UID_INVALID; + + if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_TOUCH)) + r = mkdir_parents_safe(dest, where, 0755, u, u, 0); + else + r = mkdir_p_safe(dest, where, 0755, u, u, 0); + 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; + } + } + + if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_TOUCH)) { + r = touch(where); + if (r < 0 && r != -EEXIST) { + if (fatal && r != -EROFS) + return log_error_errno(r, "Failed to create file %s: %m", where); + + log_debug_errno(r, "Failed to create file %s: %m", where); + 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; + } + + if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_PREFIX_ROOT)) { + /* Optionally prefix the mount source with the root dir. This is useful in bind + * mounts to be created within the container image before we transition into it. Note + * that MOUNT_IN_USERNS is run after we transitioned hence prefixing is not necessary + * for those. */ + r = chase(mount_table[k].what, dest, CHASE_PREFIX_ROOT, &prefixed, NULL); + if (r < 0) + return log_error_errno(r, "Failed to resolve %s%s: %m", strempty(dest), mount_table[k].what); + } + + r = mount_verbose_full( + fatal ? LOG_ERR : LOG_DEBUG, + prefixed ?: mount_table[k].what, + where, + mount_table[k].type, + mount_table[k].flags, + o, + FLAGS_SET(mount_table[k].mount_settings, MOUNT_FOLLOW_SYMLINKS)); + if (r < 0 && fatal) + return r; + } + + return 0; +} + +static int parse_mount_bind_options(const char *options, unsigned long *mount_flags, char **mount_opts, RemountIdmapping *idmapping) { + unsigned long flags = *mount_flags; + char *opts = NULL; + RemountIdmapping new_idmapping = *idmapping; + int r; + + assert(options); + + for (;;) { + _cleanup_free_ char *word = NULL; + + r = extract_first_word(&options, &word, ",", 0); + if (r < 0) + return log_error_errno(r, "Failed to extract mount option: %m"); + if (r == 0) + break; + + if (streq(word, "rbind")) + flags |= MS_REC; + else if (streq(word, "norbind")) + flags &= ~MS_REC; + else if (streq(word, "idmap")) + new_idmapping = REMOUNT_IDMAPPING_HOST_ROOT; + else if (streq(word, "noidmap")) + new_idmapping = REMOUNT_IDMAPPING_NONE; + else if (streq(word, "rootidmap")) + new_idmapping = REMOUNT_IDMAPPING_HOST_OWNER; + else + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Invalid bind mount option: %s", word); + } + + *mount_flags = flags; + *idmapping = new_idmapping; + /* in the future mount_opts will hold string options for mount(2) */ + *mount_opts = opts; + + return 0; +} + +static int mount_bind(const char *dest, CustomMount *m, uid_t uid_shift, uid_t uid_range) { + _cleanup_free_ char *mount_opts = NULL, *where = NULL; + unsigned long mount_flags = MS_BIND | MS_REC; + struct stat source_st, dest_st; + int r; + RemountIdmapping idmapping = REMOUNT_IDMAPPING_NONE; + + assert(dest); + assert(m); + + if (m->options) { + r = parse_mount_bind_options(m->options, &mount_flags, &mount_opts, &idmapping); + if (r < 0) + return r; + } + + /* If this is a bind mount from a temporary sources change ownership of the source to the container's + * root UID. Otherwise it would always show up as "nobody" if user namespacing is used. */ + if (m->rm_rf_tmpdir && chown(m->source, uid_shift, uid_shift) < 0) + return log_error_errno(errno, "Failed to chown %s: %m", m->source); + + if (stat(m->source, &source_st) < 0) + return log_error_errno(errno, "Failed to stat %s: %m", m->source); + + r = chase(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where, NULL); + 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_safe_label(dest, where, 0755, uid_shift, uid_shift, MKDIR_IGNORE_EXISTING); + 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); + + if (chown(where, uid_shift, uid_shift) < 0) + return log_error_errno(errno, "Failed to chown %s: %m", where); + } + + r = mount_nofollow_verbose(LOG_ERR, m->source, where, NULL, mount_flags, mount_opts); + if (r < 0) + return r; + + if (m->read_only) { + r = bind_remount_recursive(where, MS_RDONLY, MS_RDONLY, NULL); + if (r < 0) + return log_error_errno(r, "Read-only bind mount failed: %m"); + } + + if (idmapping != REMOUNT_IDMAPPING_NONE) { + r = remount_idmap(STRV_MAKE(where), uid_shift, uid_range, source_st.st_uid, idmapping); + if (r < 0) + return log_error_errno(r, "Failed to map ids for bind mount %s: %m", where); + } + + return 0; +} + +static int mount_tmpfs(const char *dest, CustomMount *m, uid_t uid_shift, const char *selinux_apifs_context) { + const char *options; + _cleanup_free_ char *buf = NULL, *where = NULL; + int r; + + assert(dest); + assert(m); + + r = chase(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where, NULL); + 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_nofollow_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(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where, NULL); + 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_nofollow_verbose(LOG_ERR, "overlay", where, "overlay", m->read_only ? MS_RDONLY : 0, options); +} + +static int mount_inaccessible(const char *dest, CustomMount *m) { + _cleanup_free_ char *where = NULL, *source = NULL; + struct stat st; + int r; + + assert(dest); + assert(m); + + r = chase_and_stat(m->destination, dest, CHASE_PREFIX_ROOT, &where, &st); + if (r < 0) { + log_full_errno(m->graceful ? LOG_DEBUG : LOG_ERR, r, "Failed to resolve %s/%s: %m", dest, m->destination); + return m->graceful ? 0 : r; + } + + r = mode_to_inaccessible_node(NULL, st.st_mode, &source); + if (r < 0) + return m->graceful ? 0 : r; + + r = mount_nofollow_verbose(m->graceful ? LOG_DEBUG : LOG_ERR, source, where, NULL, MS_BIND, NULL); + if (r < 0) + return m->graceful ? 0 : r; + + r = mount_nofollow_verbose(m->graceful ? LOG_DEBUG : LOG_ERR, NULL, where, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL); + if (r < 0) { + (void) umount_verbose(m->graceful ? LOG_DEBUG : LOG_ERR, where, UMOUNT_NOFOLLOW); + return m->graceful ? 0 : r; + } + + return 0; +} + +static int mount_arbitrary(const char *dest, CustomMount *m) { + _cleanup_free_ char *where = NULL; + int r; + + assert(dest); + assert(m); + + r = chase(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where, NULL); + 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 mount %s failed: %m", where); + } + + return mount_nofollow_verbose(LOG_ERR, m->source, where, m->type_argument, 0, m->options); +} + +int mount_custom( + const char *dest, + CustomMount *mounts, size_t n, + uid_t uid_shift, + uid_t uid_range, + const char *selinux_apifs_context, + MountSettingsMask mount_settings) { + int r; + + assert(dest); + + for (size_t i = 0; i < n; i++) { + CustomMount *m = mounts + i; + + if (FLAGS_SET(mount_settings, MOUNT_IN_USERNS) != m->in_userns) + continue; + + if (FLAGS_SET(mount_settings, MOUNT_ROOT_ONLY) && !path_equal(m->destination, "/")) + continue; + + if (FLAGS_SET(mount_settings, MOUNT_NON_ROOT_ONLY) && path_equal(m->destination, "/")) + continue; + + switch (m->type) { + + case CUSTOM_MOUNT_BIND: + r = mount_bind(dest, m, uid_shift, uid_range); + break; + + case CUSTOM_MOUNT_TMPFS: + r = mount_tmpfs(dest, m, uid_shift, selinux_apifs_context); + break; + + case CUSTOM_MOUNT_OVERLAY: + r = mount_overlay(dest, m); + break; + + case CUSTOM_MOUNT_INACCESSIBLE: + r = mount_inaccessible(dest, m); + break; + + case CUSTOM_MOUNT_ARBITRARY: + r = mount_arbitrary(dest, m); + break; + + default: + assert_not_reached(); + } + + if (r < 0) + return r; + } + + return 0; +} + +bool has_custom_root_mount(const CustomMount *mounts, size_t n) { + for (size_t i = 0; i < n; i++) + if (path_equal(mounts[i].destination, "/")) + return true; + + return false; +} + +static int setup_volatile_state(const char *directory, uid_t uid_shift, const char *selinux_apifs_context) { + _cleanup_free_ char *buf = NULL; + const char *p, *options; + int r; + + assert(directory); + + /* --volatile=state means we simply overmount /var with a tmpfs, and the rest read-only. */ + + r = bind_remount_recursive(directory, MS_RDONLY, MS_RDONLY, 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=0755" TMPFS_LIMITS_VOLATILE_STATE; + 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_nofollow_verbose(LOG_ERR, "tmpfs", p, "tmpfs", MS_STRICTATIME, options); +} + +static int setup_volatile_yes(const char *directory, uid_t uid_shift, const char *selinux_apifs_context) { + bool tmpfs_mounted = false, bind_mounted = false; + char template[] = "/tmp/nspawn-volatile-XXXXXX"; + _cleanup_free_ char *buf = NULL, *bindir = NULL; + const char *f, *t, *options; + struct stat st; + int r; + + assert(directory); + + /* --volatile=yes means we mount a tmpfs to the root dir, and the original /usr to use inside it, and + * that read-only. Before we start setting this up let's validate if the image has the /usr merge + * implemented, and let's output a friendly log message if it hasn't. */ + + bindir = path_join(directory, "/bin"); + if (!bindir) + return log_oom(); + if (lstat(bindir, &st) < 0) { + if (errno != ENOENT) + return log_error_errno(errno, "Failed to stat /bin directory below image: %m"); + + /* ENOENT is fine, just means the image is probably just a naked /usr and we can create the + * rest. */ + } else if (S_ISDIR(st.st_mode)) + return log_error_errno(SYNTHETIC_ERRNO(EISDIR), + "Sorry, --volatile=yes mode is not supported with OS images that have not merged /bin/, /sbin/, /lib/, /lib64/ into /usr/. " + "Please work with your distribution and help them adopt the merged /usr scheme."); + else if (!S_ISLNK(st.st_mode)) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Error starting image: if --volatile=yes is used /bin must be a symlink (for merged /usr support) or non-existent (in which case a symlink is created automatically)."); + + if (!mkdtemp(template)) + return log_error_errno(errno, "Failed to create temporary directory: %m"); + + options = "mode=0755" TMPFS_LIMITS_ROOTFS; + r = tmpfs_patch_options(options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf); + if (r < 0) + goto fail; + if (r > 0) + options = buf; + + r = mount_nofollow_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_nofollow_verbose(LOG_ERR, f, t, NULL, MS_BIND|MS_REC, NULL); + if (r < 0) + goto fail; + + bind_mounted = true; + + r = bind_remount_recursive(t, MS_RDONLY, MS_RDONLY, NULL); + if (r < 0) { + log_error_errno(r, "Failed to remount %s read-only: %m", t); + goto fail; + } + + r = mount_nofollow_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(LOG_ERR, t, UMOUNT_NOFOLLOW); + + if (tmpfs_mounted) + (void) umount_verbose(LOG_ERR, template, UMOUNT_NOFOLLOW); + + (void) rmdir(template); + return r; +} + +static int setup_volatile_overlay(const char *directory, uid_t uid_shift, const char *selinux_apifs_context) { + _cleanup_free_ char *buf = NULL, *escaped_directory = NULL, *escaped_upper = NULL, *escaped_work = NULL; + char template[] = "/tmp/nspawn-volatile-XXXXXX"; + const char *upper, *work, *options; + bool tmpfs_mounted = false; + int r; + + assert(directory); + + /* --volatile=overlay means we mount an overlayfs to the root dir. */ + + if (!mkdtemp(template)) + return log_error_errno(errno, "Failed to create temporary directory: %m"); + + options = "mode=0755" TMPFS_LIMITS_ROOTFS; + r = tmpfs_patch_options(options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf); + if (r < 0) + goto finish; + if (r > 0) + options = buf; + + r = mount_nofollow_verbose(LOG_ERR, "tmpfs", template, "tmpfs", MS_STRICTATIME, options); + if (r < 0) + goto finish; + + tmpfs_mounted = true; + + upper = strjoina(template, "/upper"); + work = strjoina(template, "/work"); + + if (mkdir(upper, 0755) < 0) { + r = log_error_errno(errno, "Failed to create %s: %m", upper); + goto finish; + } + if (mkdir(work, 0755) < 0) { + r = log_error_errno(errno, "Failed to create %s: %m", work); + goto finish; + } + + /* And now, let's overmount the root dir with an overlayfs that uses the root dir as lower dir. It's kinda nice + * that the kernel allows us to do that without going through some mount point rearrangements. */ + + escaped_directory = shell_escape(directory, ",:"); + escaped_upper = shell_escape(upper, ",:"); + escaped_work = shell_escape(work, ",:"); + if (!escaped_directory || !escaped_upper || !escaped_work) { + r = -ENOMEM; + goto finish; + } + + options = strjoina("lowerdir=", escaped_directory, ",upperdir=", escaped_upper, ",workdir=", escaped_work); + r = mount_nofollow_verbose(LOG_ERR, "overlay", directory, "overlay", 0, options); + +finish: + if (tmpfs_mounted) + (void) umount_verbose(LOG_ERR, template, UMOUNT_NOFOLLOW); + + (void) rmdir(template); + return r; +} + +int setup_volatile_mode( + const char *directory, + VolatileMode mode, + uid_t uid_shift, + const char *selinux_apifs_context) { + + switch (mode) { + + case VOLATILE_YES: + return setup_volatile_yes(directory, uid_shift, selinux_apifs_context); + + case VOLATILE_STATE: + return setup_volatile_state(directory, uid_shift, selinux_apifs_context); + + case VOLATILE_OVERLAY: + return setup_volatile_overlay(directory, uid_shift, selinux_apifs_context); + + default: + return 0; + } +} + +/* 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 + * initrd. + * + * 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 = path_join(directory, pivot_root_new); + if (!directory_pivot_root_new) + return log_oom(); + + /* Remount directory_pivot_root_new to make it movable. */ + r = mount_nofollow_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 = path_join(pivot_tmp, pivot_root_old); + if (!pivot_tmp_pivot_root_old) { + r = log_oom(); + goto done; + } + + r = mount_nofollow_verbose(LOG_ERR, directory_pivot_root_new, pivot_tmp, NULL, MS_MOVE, NULL); + if (r < 0) + goto done; + + r = mount_nofollow_verbose(LOG_ERR, directory, pivot_tmp_pivot_root_old, NULL, MS_MOVE, NULL); + if (r < 0) + goto done; + + r = mount_nofollow_verbose(LOG_ERR, pivot_tmp, directory, NULL, MS_MOVE, NULL); + if (r < 0) + goto done; + } else { + r = mount_nofollow_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; +} + +#define NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS "/run/host/proc" +#define NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS "/run/host/sys" + +int pin_fully_visible_fs(void) { + int r; + + (void) mkdir_p(NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS, 0755); + (void) mkdir_p(NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS, 0755); + + r = mount_follow_verbose(LOG_ERR, "proc", NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS, "proc", PROC_DEFAULT_MOUNT_FLAGS, NULL); + if (r < 0) + return r; + + r = mount_follow_verbose(LOG_ERR, "sysfs", NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS, "sysfs", SYS_DEFAULT_MOUNT_FLAGS, NULL); + if (r < 0) + return r; + + return 0; +} + +static int do_wipe_fully_visible_fs(void) { + if (umount2(NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS, MNT_DETACH) < 0) + return log_error_errno(errno, "Failed to unmount temporary proc: %m"); + + if (rmdir(NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS) < 0) + return log_error_errno(errno, "Failed to remove temporary proc mountpoint: %m"); + + if (umount2(NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS, MNT_DETACH) < 0) + return log_error_errno(errno, "Failed to unmount temporary sys: %m"); + + if (rmdir(NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS) < 0) + return log_error_errno(errno, "Failed to remove temporary sys mountpoint: %m"); + + return 0; +} + +int wipe_fully_visible_fs(int mntns_fd) { + _cleanup_close_ int orig_mntns_fd = -EBADF; + int r, rr; + + r = namespace_open(0, NULL, &orig_mntns_fd, NULL, NULL, NULL); + if (r < 0) + return log_error_errno(r, "Failed to pin originating mount namespace: %m"); + + r = namespace_enter(-EBADF, mntns_fd, -EBADF, -EBADF, -EBADF); + if (r < 0) + return log_error_errno(r, "Failed to enter mount namespace: %m"); + + rr = do_wipe_fully_visible_fs(); + + r = namespace_enter(-EBADF, orig_mntns_fd, -EBADF, -EBADF, -EBADF); + if (r < 0) + return log_error_errno(r, "Failed to enter original mount namespace: %m"); + + return rr; +} |