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-rw-r--r--src/core/namespace.c1733
1 files changed, 1733 insertions, 0 deletions
diff --git a/src/core/namespace.c b/src/core/namespace.c
new file mode 100644
index 0000000..7f553a4
--- /dev/null
+++ b/src/core/namespace.c
@@ -0,0 +1,1733 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <sched.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <linux/fs.h>
+
+#include "alloc-util.h"
+#include "base-filesystem.h"
+#include "dev-setup.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "label.h"
+#include "loop-util.h"
+#include "loopback-setup.h"
+#include "missing.h"
+#include "mkdir.h"
+#include "mount-util.h"
+#include "mountpoint-util.h"
+#include "namespace.h"
+#include "path-util.h"
+#include "selinux-util.h"
+#include "socket-util.h"
+#include "stat-util.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "strv.h"
+#include "umask-util.h"
+#include "user-util.h"
+#include "util.h"
+
+#define DEV_MOUNT_OPTIONS (MS_NOSUID|MS_STRICTATIME|MS_NOEXEC)
+
+typedef enum MountMode {
+ /* This is ordered by priority! */
+ INACCESSIBLE,
+ BIND_MOUNT,
+ BIND_MOUNT_RECURSIVE,
+ PRIVATE_TMP,
+ PRIVATE_DEV,
+ BIND_DEV,
+ EMPTY_DIR,
+ SYSFS,
+ PROCFS,
+ READONLY,
+ READWRITE,
+ TMPFS,
+} MountMode;
+
+typedef struct MountEntry {
+ const char *path_const; /* Memory allocated on stack or static */
+ MountMode mode:5;
+ bool ignore:1; /* Ignore if path does not exist? */
+ bool has_prefix:1; /* Already is prefixed by the root dir? */
+ bool read_only:1; /* Shall this mount point be read-only? */
+ bool applied:1; /* Already applied */
+ char *path_malloc; /* Use this instead of 'path_const' if we had to allocate memory */
+ const char *source_const; /* The source path, for bind mounts */
+ char *source_malloc;
+ const char *options_const;/* Mount options for tmpfs */
+ char *options_malloc;
+ unsigned long flags; /* Mount flags used by EMPTY_DIR and TMPFS. Do not include MS_RDONLY here, but please use read_only. */
+ unsigned n_followed;
+} MountEntry;
+
+/* If MountAPIVFS= is used, let's mount /sys and /proc into the it, but only as a fallback if the user hasn't mounted
+ * something there already. These mounts are hence overridden by any other explicitly configured mounts. */
+static const MountEntry apivfs_table[] = {
+ { "/proc", PROCFS, false },
+ { "/dev", BIND_DEV, false },
+ { "/sys", SYSFS, false },
+};
+
+/* ProtectKernelTunables= option and the related filesystem APIs */
+static const MountEntry protect_kernel_tunables_table[] = {
+ { "/proc/acpi", READONLY, true },
+ { "/proc/apm", READONLY, true }, /* Obsolete API, there's no point in permitting access to this, ever */
+ { "/proc/asound", READONLY, true },
+ { "/proc/bus", READONLY, true },
+ { "/proc/fs", READONLY, true },
+ { "/proc/irq", READONLY, true },
+ { "/proc/kallsyms", INACCESSIBLE, true },
+ { "/proc/kcore", INACCESSIBLE, true },
+ { "/proc/latency_stats", READONLY, true },
+ { "/proc/mtrr", READONLY, true },
+ { "/proc/scsi", READONLY, true },
+ { "/proc/sys", READONLY, false },
+ { "/proc/sysrq-trigger", READONLY, true },
+ { "/proc/timer_stats", READONLY, true },
+ { "/sys", READONLY, false },
+ { "/sys/fs/bpf", READONLY, true },
+ { "/sys/fs/cgroup", READWRITE, false }, /* READONLY is set by ProtectControlGroups= option */
+ { "/sys/fs/selinux", READWRITE, true },
+ { "/sys/kernel/debug", READONLY, true },
+ { "/sys/kernel/tracing", READONLY, true },
+};
+
+/* ProtectKernelModules= option */
+static const MountEntry protect_kernel_modules_table[] = {
+#if HAVE_SPLIT_USR
+ { "/lib/modules", INACCESSIBLE, true },
+#endif
+ { "/usr/lib/modules", INACCESSIBLE, true },
+};
+
+/*
+ * ProtectHome=read-only table, protect $HOME and $XDG_RUNTIME_DIR and rest of
+ * system should be protected by ProtectSystem=
+ */
+static const MountEntry protect_home_read_only_table[] = {
+ { "/home", READONLY, true },
+ { "/run/user", READONLY, true },
+ { "/root", READONLY, true },
+};
+
+/* ProtectHome=tmpfs table */
+static const MountEntry protect_home_tmpfs_table[] = {
+ { "/home", TMPFS, true, .read_only = true, .options_const = "mode=0755", .flags = MS_NODEV|MS_STRICTATIME },
+ { "/run/user", TMPFS, true, .read_only = true, .options_const = "mode=0755", .flags = MS_NODEV|MS_STRICTATIME },
+ { "/root", TMPFS, true, .read_only = true, .options_const = "mode=0700", .flags = MS_NODEV|MS_STRICTATIME },
+};
+
+/* ProtectHome=yes table */
+static const MountEntry protect_home_yes_table[] = {
+ { "/home", INACCESSIBLE, true },
+ { "/run/user", INACCESSIBLE, true },
+ { "/root", INACCESSIBLE, true },
+};
+
+/* ProtectSystem=yes table */
+static const MountEntry protect_system_yes_table[] = {
+ { "/usr", READONLY, false },
+ { "/boot", READONLY, true },
+ { "/efi", READONLY, true },
+#if HAVE_SPLIT_USR
+ { "/lib", READONLY, true },
+ { "/lib64", READONLY, true },
+ { "/bin", READONLY, true },
+# if HAVE_SPLIT_BIN
+ { "/sbin", READONLY, true },
+# endif
+#endif
+};
+
+/* ProtectSystem=full includes ProtectSystem=yes */
+static const MountEntry protect_system_full_table[] = {
+ { "/usr", READONLY, false },
+ { "/boot", READONLY, true },
+ { "/efi", READONLY, true },
+ { "/etc", READONLY, false },
+#if HAVE_SPLIT_USR
+ { "/lib", READONLY, true },
+ { "/lib64", READONLY, true },
+ { "/bin", READONLY, true },
+# if HAVE_SPLIT_BIN
+ { "/sbin", READONLY, true },
+# endif
+#endif
+};
+
+/*
+ * ProtectSystem=strict table. In this strict mode, we mount everything
+ * read-only, except for /proc, /dev, /sys which are the kernel API VFS,
+ * which are left writable, but PrivateDevices= + ProtectKernelTunables=
+ * protect those, and these options should be fully orthogonal.
+ * (And of course /home and friends are also left writable, as ProtectHome=
+ * shall manage those, orthogonally).
+ */
+static const MountEntry protect_system_strict_table[] = {
+ { "/", READONLY, false },
+ { "/proc", READWRITE, false }, /* ProtectKernelTunables= */
+ { "/sys", READWRITE, false }, /* ProtectKernelTunables= */
+ { "/dev", READWRITE, false }, /* PrivateDevices= */
+ { "/home", READWRITE, true }, /* ProtectHome= */
+ { "/run/user", READWRITE, true }, /* ProtectHome= */
+ { "/root", READWRITE, true }, /* ProtectHome= */
+};
+
+static const char *mount_entry_path(const MountEntry *p) {
+ assert(p);
+
+ /* Returns the path of this bind mount. If the malloc()-allocated ->path_buffer field is set we return that,
+ * otherwise the stack/static ->path field is returned. */
+
+ return p->path_malloc ?: p->path_const;
+}
+
+static bool mount_entry_read_only(const MountEntry *p) {
+ assert(p);
+
+ return p->read_only || IN_SET(p->mode, READONLY, INACCESSIBLE);
+}
+
+static const char *mount_entry_source(const MountEntry *p) {
+ assert(p);
+
+ return p->source_malloc ?: p->source_const;
+}
+
+static const char *mount_entry_options(const MountEntry *p) {
+ assert(p);
+
+ return p->options_malloc ?: p->options_const;
+}
+
+static void mount_entry_done(MountEntry *p) {
+ assert(p);
+
+ p->path_malloc = mfree(p->path_malloc);
+ p->source_malloc = mfree(p->source_malloc);
+ p->options_malloc = mfree(p->options_malloc);
+}
+
+static int append_access_mounts(MountEntry **p, char **strv, MountMode mode, bool forcibly_require_prefix) {
+ char **i;
+
+ assert(p);
+
+ /* Adds a list of user-supplied READWRITE/READONLY/INACCESSIBLE entries */
+
+ STRV_FOREACH(i, strv) {
+ bool ignore = false, needs_prefix = false;
+ const char *e = *i;
+
+ /* Look for any prefixes */
+ if (startswith(e, "-")) {
+ e++;
+ ignore = true;
+ }
+ if (startswith(e, "+")) {
+ e++;
+ needs_prefix = true;
+ }
+
+ if (!path_is_absolute(e))
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Path is not absolute: %s", e);
+
+ *((*p)++) = (MountEntry) {
+ .path_const = e,
+ .mode = mode,
+ .ignore = ignore,
+ .has_prefix = !needs_prefix && !forcibly_require_prefix,
+ };
+ }
+
+ return 0;
+}
+
+static int append_empty_dir_mounts(MountEntry **p, char **strv) {
+ char **i;
+
+ assert(p);
+
+ /* Adds tmpfs mounts to provide readable but empty directories. This is primarily used to implement the
+ * "/private/" boundary directories for DynamicUser=1. */
+
+ STRV_FOREACH(i, strv) {
+
+ *((*p)++) = (MountEntry) {
+ .path_const = *i,
+ .mode = EMPTY_DIR,
+ .ignore = false,
+ .read_only = true,
+ .options_const = "mode=755",
+ .flags = MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME,
+ };
+ }
+
+ return 0;
+}
+
+static int append_bind_mounts(MountEntry **p, const BindMount *binds, size_t n) {
+ size_t i;
+
+ assert(p);
+
+ for (i = 0; i < n; i++) {
+ const BindMount *b = binds + i;
+
+ *((*p)++) = (MountEntry) {
+ .path_const = b->destination,
+ .mode = b->recursive ? BIND_MOUNT_RECURSIVE : BIND_MOUNT,
+ .read_only = b->read_only,
+ .source_const = b->source,
+ .ignore = b->ignore_enoent,
+ };
+ }
+
+ return 0;
+}
+
+static int append_tmpfs_mounts(MountEntry **p, const TemporaryFileSystem *tmpfs, size_t n) {
+ size_t i;
+ int r;
+
+ assert(p);
+
+ for (i = 0; i < n; i++) {
+ const TemporaryFileSystem *t = tmpfs + i;
+ _cleanup_free_ char *o = NULL, *str = NULL;
+ unsigned long flags;
+ bool ro = false;
+
+ if (!path_is_absolute(t->path))
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Path is not absolute: %s",
+ t->path);
+
+ str = strjoin("mode=0755,", t->options);
+ if (!str)
+ return -ENOMEM;
+
+ r = mount_option_mangle(str, MS_NODEV|MS_STRICTATIME, &flags, &o);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to parse mount option '%s': %m", str);
+
+ ro = flags & MS_RDONLY;
+ if (ro)
+ flags ^= MS_RDONLY;
+
+ *((*p)++) = (MountEntry) {
+ .path_const = t->path,
+ .mode = TMPFS,
+ .read_only = ro,
+ .options_malloc = TAKE_PTR(o),
+ .flags = flags,
+ };
+ }
+
+ return 0;
+}
+
+static int append_static_mounts(MountEntry **p, const MountEntry *mounts, size_t n, bool ignore_protect) {
+ size_t i;
+
+ assert(p);
+ assert(mounts);
+
+ /* Adds a list of static pre-defined entries */
+
+ for (i = 0; i < n; i++)
+ *((*p)++) = (MountEntry) {
+ .path_const = mount_entry_path(mounts+i),
+ .mode = mounts[i].mode,
+ .ignore = mounts[i].ignore || ignore_protect,
+ };
+
+ return 0;
+}
+
+static int append_protect_home(MountEntry **p, ProtectHome protect_home, bool ignore_protect) {
+ assert(p);
+
+ switch (protect_home) {
+
+ case PROTECT_HOME_NO:
+ return 0;
+
+ case PROTECT_HOME_READ_ONLY:
+ return append_static_mounts(p, protect_home_read_only_table, ELEMENTSOF(protect_home_read_only_table), ignore_protect);
+
+ case PROTECT_HOME_TMPFS:
+ return append_static_mounts(p, protect_home_tmpfs_table, ELEMENTSOF(protect_home_tmpfs_table), ignore_protect);
+
+ case PROTECT_HOME_YES:
+ return append_static_mounts(p, protect_home_yes_table, ELEMENTSOF(protect_home_yes_table), ignore_protect);
+
+ default:
+ assert_not_reached("Unexpected ProtectHome= value");
+ }
+}
+
+static int append_protect_system(MountEntry **p, ProtectSystem protect_system, bool ignore_protect) {
+ assert(p);
+
+ switch (protect_system) {
+
+ case PROTECT_SYSTEM_NO:
+ return 0;
+
+ case PROTECT_SYSTEM_STRICT:
+ return append_static_mounts(p, protect_system_strict_table, ELEMENTSOF(protect_system_strict_table), ignore_protect);
+
+ case PROTECT_SYSTEM_YES:
+ return append_static_mounts(p, protect_system_yes_table, ELEMENTSOF(protect_system_yes_table), ignore_protect);
+
+ case PROTECT_SYSTEM_FULL:
+ return append_static_mounts(p, protect_system_full_table, ELEMENTSOF(protect_system_full_table), ignore_protect);
+
+ default:
+ assert_not_reached("Unexpected ProtectSystem= value");
+ }
+}
+
+static int mount_path_compare(const MountEntry *a, const MountEntry *b) {
+ int d;
+
+ /* If the paths are not equal, then order prefixes first */
+ d = path_compare(mount_entry_path(a), mount_entry_path(b));
+ if (d != 0)
+ return d;
+
+ /* If the paths are equal, check the mode */
+ return CMP((int) a->mode, (int) b->mode);
+}
+
+static int prefix_where_needed(MountEntry *m, size_t n, const char *root_directory) {
+ size_t i;
+
+ /* Prefixes all paths in the bind mount table with the root directory if the entry needs that. */
+
+ for (i = 0; i < n; i++) {
+ char *s;
+
+ if (m[i].has_prefix)
+ continue;
+
+ s = prefix_root(root_directory, mount_entry_path(m+i));
+ if (!s)
+ return -ENOMEM;
+
+ free_and_replace(m[i].path_malloc, s);
+ m[i].has_prefix = true;
+ }
+
+ return 0;
+}
+
+static void drop_duplicates(MountEntry *m, size_t *n) {
+ MountEntry *f, *t, *previous;
+
+ assert(m);
+ assert(n);
+
+ /* Drops duplicate entries. Expects that the array is properly ordered already. */
+
+ for (f = m, t = m, previous = NULL; f < m + *n; f++) {
+
+ /* The first one wins (which is the one with the more restrictive mode), see mount_path_compare()
+ * above. Note that we only drop duplicates that haven't been mounted yet. */
+ if (previous &&
+ path_equal(mount_entry_path(f), mount_entry_path(previous)) &&
+ !f->applied && !previous->applied) {
+ log_debug("%s is duplicate.", mount_entry_path(f));
+ previous->read_only = previous->read_only || mount_entry_read_only(f); /* Propagate the read-only flag to the remaining entry */
+ mount_entry_done(f);
+ continue;
+ }
+
+ *t = *f;
+ previous = t;
+ t++;
+ }
+
+ *n = t - m;
+}
+
+static void drop_inaccessible(MountEntry *m, size_t *n) {
+ MountEntry *f, *t;
+ const char *clear = NULL;
+
+ assert(m);
+ assert(n);
+
+ /* Drops all entries obstructed by another entry further up the tree. Expects that the array is properly
+ * ordered already. */
+
+ for (f = m, t = m; f < m + *n; f++) {
+
+ /* If we found a path set for INACCESSIBLE earlier, and this entry has it as prefix we should drop
+ * it, as inaccessible paths really should drop the entire subtree. */
+ if (clear && path_startswith(mount_entry_path(f), clear)) {
+ log_debug("%s is masked by %s.", mount_entry_path(f), clear);
+ mount_entry_done(f);
+ continue;
+ }
+
+ clear = f->mode == INACCESSIBLE ? mount_entry_path(f) : NULL;
+
+ *t = *f;
+ t++;
+ }
+
+ *n = t - m;
+}
+
+static void drop_nop(MountEntry *m, size_t *n) {
+ MountEntry *f, *t;
+
+ assert(m);
+ assert(n);
+
+ /* Drops all entries which have an immediate parent that has the same type, as they are redundant. Assumes the
+ * list is ordered by prefixes. */
+
+ for (f = m, t = m; f < m + *n; f++) {
+
+ /* Only suppress such subtrees for READONLY and READWRITE entries */
+ if (IN_SET(f->mode, READONLY, READWRITE)) {
+ MountEntry *p;
+ bool found = false;
+
+ /* Now let's find the first parent of the entry we are looking at. */
+ for (p = t-1; p >= m; p--) {
+ if (path_startswith(mount_entry_path(f), mount_entry_path(p))) {
+ found = true;
+ break;
+ }
+ }
+
+ /* We found it, let's see if it's the same mode, if so, we can drop this entry */
+ if (found && p->mode == f->mode) {
+ log_debug("%s is redundant by %s", mount_entry_path(f), mount_entry_path(p));
+ mount_entry_done(f);
+ continue;
+ }
+ }
+
+ *t = *f;
+ t++;
+ }
+
+ *n = t - m;
+}
+
+static void drop_outside_root(const char *root_directory, MountEntry *m, size_t *n) {
+ MountEntry *f, *t;
+
+ assert(m);
+ assert(n);
+
+ /* Nothing to do */
+ if (!root_directory)
+ return;
+
+ /* Drops all mounts that are outside of the root directory. */
+
+ for (f = m, t = m; f < m + *n; f++) {
+
+ if (!path_startswith(mount_entry_path(f), root_directory)) {
+ log_debug("%s is outside of root directory.", mount_entry_path(f));
+ mount_entry_done(f);
+ continue;
+ }
+
+ *t = *f;
+ t++;
+ }
+
+ *n = t - m;
+}
+
+static int clone_device_node(
+ const char *d,
+ const char *temporary_mount,
+ bool *make_devnode) {
+
+ _cleanup_free_ char *sl = NULL;
+ const char *dn, *bn, *t;
+ struct stat st;
+ int r;
+
+ if (stat(d, &st) < 0) {
+ if (errno == ENOENT) {
+ log_debug_errno(errno, "Device node '%s' to clone does not exist, ignoring.", d);
+ return -ENXIO;
+ }
+
+ return log_debug_errno(errno, "Failed to stat() device node '%s' to clone, ignoring: %m", d);
+ }
+
+ if (!S_ISBLK(st.st_mode) &&
+ !S_ISCHR(st.st_mode))
+ return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Device node '%s' to clone is not a device node, ignoring.",
+ d);
+
+ dn = strjoina(temporary_mount, d);
+
+ /* First, try to create device node properly */
+ if (*make_devnode) {
+ mac_selinux_create_file_prepare(d, st.st_mode);
+ r = mknod(dn, st.st_mode, st.st_rdev);
+ mac_selinux_create_file_clear();
+ if (r >= 0)
+ goto add_symlink;
+ if (errno != EPERM)
+ return log_debug_errno(errno, "mknod failed for %s: %m", d);
+
+ /* This didn't work, let's not try this again for the next iterations. */
+ *make_devnode = false;
+ }
+
+ /* We're about to fallback to bind-mounting the device
+ * node. So create a dummy bind-mount target. */
+ mac_selinux_create_file_prepare(d, 0);
+ r = mknod(dn, S_IFREG, 0);
+ mac_selinux_create_file_clear();
+ if (r < 0 && errno != EEXIST)
+ return log_debug_errno(errno, "mknod() fallback failed for '%s': %m", d);
+
+ /* Fallback to bind-mounting:
+ * The assumption here is that all used device nodes carry standard
+ * properties. Specifically, the devices nodes we bind-mount should
+ * either be owned by root:root or root:tty (e.g. /dev/tty, /dev/ptmx)
+ * and should not carry ACLs. */
+ if (mount(d, dn, NULL, MS_BIND, NULL) < 0)
+ return log_debug_errno(errno, "Bind mounting failed for '%s': %m", d);
+
+add_symlink:
+ bn = path_startswith(d, "/dev/");
+ if (!bn)
+ return 0;
+
+ /* Create symlinks like /dev/char/1:9 → ../urandom */
+ if (asprintf(&sl, "%s/dev/%s/%u:%u", temporary_mount, S_ISCHR(st.st_mode) ? "char" : "block", major(st.st_rdev), minor(st.st_rdev)) < 0)
+ return log_oom();
+
+ (void) mkdir_parents(sl, 0755);
+
+ t = strjoina("../", bn);
+
+ if (symlink(t, sl) < 0)
+ log_debug_errno(errno, "Failed to symlink '%s' to '%s', ignoring: %m", t, sl);
+
+ return 0;
+}
+
+static int mount_private_dev(MountEntry *m) {
+ static const char devnodes[] =
+ "/dev/null\0"
+ "/dev/zero\0"
+ "/dev/full\0"
+ "/dev/random\0"
+ "/dev/urandom\0"
+ "/dev/tty\0";
+
+ char temporary_mount[] = "/tmp/namespace-dev-XXXXXX";
+ const char *d, *dev = NULL, *devpts = NULL, *devshm = NULL, *devhugepages = NULL, *devmqueue = NULL, *devlog = NULL, *devptmx = NULL;
+ bool can_mknod = true;
+ _cleanup_umask_ mode_t u;
+ int r;
+
+ assert(m);
+
+ u = umask(0000);
+
+ if (!mkdtemp(temporary_mount))
+ return log_debug_errno(errno, "Failed to create temporary directory '%s': %m", temporary_mount);
+
+ dev = strjoina(temporary_mount, "/dev");
+ (void) mkdir(dev, 0755);
+ if (mount("tmpfs", dev, "tmpfs", DEV_MOUNT_OPTIONS, "mode=755") < 0) {
+ r = log_debug_errno(errno, "Failed to mount tmpfs on '%s': %m", dev);
+ goto fail;
+ }
+
+ devpts = strjoina(temporary_mount, "/dev/pts");
+ (void) mkdir(devpts, 0755);
+ if (mount("/dev/pts", devpts, NULL, MS_BIND, NULL) < 0) {
+ r = log_debug_errno(errno, "Failed to bind mount /dev/pts on '%s': %m", devpts);
+ goto fail;
+ }
+
+ /* /dev/ptmx can either be a device node or a symlink to /dev/pts/ptmx.
+ * When /dev/ptmx a device node, /dev/pts/ptmx has 000 permissions making it inaccessible.
+ * Thus, in that case make a clone.
+ * In nspawn and other containers it will be a symlink, in that case make it a symlink. */
+ r = is_symlink("/dev/ptmx");
+ if (r < 0) {
+ log_debug_errno(r, "Failed to detect whether /dev/ptmx is a symlink or not: %m");
+ goto fail;
+ } else if (r > 0) {
+ devptmx = strjoina(temporary_mount, "/dev/ptmx");
+ if (symlink("pts/ptmx", devptmx) < 0) {
+ r = log_debug_errno(errno, "Failed to create a symlink '%s' to pts/ptmx: %m", devptmx);
+ goto fail;
+ }
+ } else {
+ r = clone_device_node("/dev/ptmx", temporary_mount, &can_mknod);
+ if (r < 0)
+ goto fail;
+ }
+
+ devshm = strjoina(temporary_mount, "/dev/shm");
+ (void) mkdir(devshm, 0755);
+ r = mount("/dev/shm", devshm, NULL, MS_BIND, NULL);
+ if (r < 0) {
+ r = log_debug_errno(errno, "Failed to bind mount /dev/shm on '%s': %m", devshm);
+ goto fail;
+ }
+
+ devmqueue = strjoina(temporary_mount, "/dev/mqueue");
+ (void) mkdir(devmqueue, 0755);
+ if (mount("/dev/mqueue", devmqueue, NULL, MS_BIND, NULL) < 0)
+ log_debug_errno(errno, "Failed to bind mount /dev/mqueue on '%s', ignoring: %m", devmqueue);
+
+ devhugepages = strjoina(temporary_mount, "/dev/hugepages");
+ (void) mkdir(devhugepages, 0755);
+ if (mount("/dev/hugepages", devhugepages, NULL, MS_BIND, NULL) < 0)
+ log_debug_errno(errno, "Failed to bind mount /dev/hugepages on '%s', ignoring: %m", devhugepages);
+
+ devlog = strjoina(temporary_mount, "/dev/log");
+ if (symlink("/run/systemd/journal/dev-log", devlog) < 0)
+ log_debug_errno(errno, "Failed to create a symlink '%s' to /run/systemd/journal/dev-log, ignoring: %m", devlog);
+
+ NULSTR_FOREACH(d, devnodes) {
+ r = clone_device_node(d, temporary_mount, &can_mknod);
+ /* ENXIO means the the *source* is not a device file, skip creation in that case */
+ if (r < 0 && r != -ENXIO)
+ goto fail;
+ }
+
+ r = dev_setup(temporary_mount, UID_INVALID, GID_INVALID);
+ if (r < 0)
+ log_debug_errno(r, "Failed to setup basic device tree at '%s', ignoring: %m", temporary_mount);
+
+ /* Create the /dev directory if missing. It is more likely to be
+ * missing when the service is started with RootDirectory. This is
+ * consistent with mount units creating the mount points when missing.
+ */
+ (void) mkdir_p_label(mount_entry_path(m), 0755);
+
+ /* Unmount everything in old /dev */
+ r = umount_recursive(mount_entry_path(m), 0);
+ if (r < 0)
+ log_debug_errno(r, "Failed to unmount directories below '%s', ignoring: %m", mount_entry_path(m));
+
+ if (mount(dev, mount_entry_path(m), NULL, MS_MOVE, NULL) < 0) {
+ r = log_debug_errno(errno, "Failed to move mount point '%s' to '%s': %m", dev, mount_entry_path(m));
+ goto fail;
+ }
+
+ rmdir(dev);
+ rmdir(temporary_mount);
+
+ return 0;
+
+fail:
+ if (devpts)
+ umount(devpts);
+
+ if (devshm)
+ umount(devshm);
+
+ if (devhugepages)
+ umount(devhugepages);
+
+ if (devmqueue)
+ umount(devmqueue);
+
+ umount(dev);
+ rmdir(dev);
+ rmdir(temporary_mount);
+
+ return r;
+}
+
+static int mount_bind_dev(const MountEntry *m) {
+ int r;
+
+ assert(m);
+
+ /* Implements the little brother of mount_private_dev(): simply bind mounts the host's /dev into the service's
+ * /dev. This is only used when RootDirectory= is set. */
+
+ (void) mkdir_p_label(mount_entry_path(m), 0755);
+
+ r = path_is_mount_point(mount_entry_path(m), NULL, 0);
+ if (r < 0)
+ return log_debug_errno(r, "Unable to determine whether /dev is already mounted: %m");
+ if (r > 0) /* make this a NOP if /dev is already a mount point */
+ return 0;
+
+ if (mount("/dev", mount_entry_path(m), NULL, MS_BIND|MS_REC, NULL) < 0)
+ return log_debug_errno(errno, "Failed to bind mount %s: %m", mount_entry_path(m));
+
+ return 1;
+}
+
+static int mount_sysfs(const MountEntry *m) {
+ int r;
+
+ assert(m);
+
+ (void) mkdir_p_label(mount_entry_path(m), 0755);
+
+ r = path_is_mount_point(mount_entry_path(m), NULL, 0);
+ if (r < 0)
+ return log_debug_errno(r, "Unable to determine whether /sys is already mounted: %m");
+ if (r > 0) /* make this a NOP if /sys is already a mount point */
+ return 0;
+
+ /* Bind mount the host's version so that we get all child mounts of it, too. */
+ if (mount("/sys", mount_entry_path(m), NULL, MS_BIND|MS_REC, NULL) < 0)
+ return log_debug_errno(errno, "Failed to mount %s: %m", mount_entry_path(m));
+
+ return 1;
+}
+
+static int mount_procfs(const MountEntry *m) {
+ int r;
+
+ assert(m);
+
+ (void) mkdir_p_label(mount_entry_path(m), 0755);
+
+ r = path_is_mount_point(mount_entry_path(m), NULL, 0);
+ if (r < 0)
+ return log_debug_errno(r, "Unable to determine whether /proc is already mounted: %m");
+ if (r > 0) /* make this a NOP if /proc is already a mount point */
+ return 0;
+
+ /* Mount a new instance, so that we get the one that matches our user namespace, if we are running in one */
+ if (mount("proc", mount_entry_path(m), "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) < 0)
+ return log_debug_errno(errno, "Failed to mount %s: %m", mount_entry_path(m));
+
+ return 1;
+}
+
+static int mount_tmpfs(const MountEntry *m) {
+ assert(m);
+
+ /* First, get rid of everything that is below if there is anything. Then, overmount with our new tmpfs */
+
+ (void) mkdir_p_label(mount_entry_path(m), 0755);
+ (void) umount_recursive(mount_entry_path(m), 0);
+
+ if (mount("tmpfs", mount_entry_path(m), "tmpfs", m->flags, mount_entry_options(m)) < 0)
+ return log_debug_errno(errno, "Failed to mount %s: %m", mount_entry_path(m));
+
+ return 1;
+}
+
+static int follow_symlink(
+ const char *root_directory,
+ MountEntry *m) {
+
+ _cleanup_free_ char *target = NULL;
+ int r;
+
+ /* Let's chase symlinks, but only one step at a time. That's because depending where the symlink points we
+ * might need to change the order in which we mount stuff. Hence: let's normalize piecemeal, and do one step at
+ * a time by specifying CHASE_STEP. This function returns 0 if we resolved one step, and > 0 if we reached the
+ * end and already have a fully normalized name. */
+
+ r = chase_symlinks(mount_entry_path(m), root_directory, CHASE_STEP|CHASE_NONEXISTENT, &target);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to chase symlinks '%s': %m", mount_entry_path(m));
+ if (r > 0) /* Reached the end, nothing more to resolve */
+ return 1;
+
+ if (m->n_followed >= CHASE_SYMLINKS_MAX) /* put a boundary on things */
+ return log_debug_errno(SYNTHETIC_ERRNO(ELOOP),
+ "Symlink loop on '%s'.",
+ mount_entry_path(m));
+
+ log_debug("Followed mount entry path symlink %s → %s.", mount_entry_path(m), target);
+
+ free_and_replace(m->path_malloc, target);
+ m->has_prefix = true;
+
+ m->n_followed ++;
+
+ return 0;
+}
+
+static int apply_mount(
+ const char *root_directory,
+ MountEntry *m) {
+
+ bool rbind = true, make = false;
+ const char *what;
+ int r;
+
+ assert(m);
+
+ log_debug("Applying namespace mount on %s", mount_entry_path(m));
+
+ switch (m->mode) {
+
+ case INACCESSIBLE: {
+ struct stat target;
+
+ /* First, get rid of everything that is below if there
+ * is anything... Then, overmount it with an
+ * inaccessible path. */
+ (void) umount_recursive(mount_entry_path(m), 0);
+
+ if (lstat(mount_entry_path(m), &target) < 0) {
+ if (errno == ENOENT && m->ignore)
+ return 0;
+
+ return log_debug_errno(errno, "Failed to lstat() %s to determine what to mount over it: %m", mount_entry_path(m));
+ }
+
+ what = mode_to_inaccessible_node(target.st_mode);
+ if (!what)
+ return log_debug_errno(SYNTHETIC_ERRNO(ELOOP),
+ "File type not supported for inaccessible mounts. Note that symlinks are not allowed");
+ break;
+ }
+
+ case READONLY:
+ case READWRITE:
+ r = path_is_mount_point(mount_entry_path(m), root_directory, 0);
+ if (r == -ENOENT && m->ignore)
+ return 0;
+ if (r < 0)
+ return log_debug_errno(r, "Failed to determine whether %s is already a mount point: %m", mount_entry_path(m));
+ if (r > 0) /* Nothing to do here, it is already a mount. We just later toggle the MS_RDONLY bit for the mount point if needed. */
+ return 0;
+ /* This isn't a mount point yet, let's make it one. */
+ what = mount_entry_path(m);
+ break;
+
+ case BIND_MOUNT:
+ rbind = false;
+
+ _fallthrough_;
+ case BIND_MOUNT_RECURSIVE: {
+ _cleanup_free_ char *chased = NULL;
+
+ /* Since mount() will always follow symlinks we chase the symlinks on our own first. Note that bind
+ * mount source paths are always relative to the host root, hence we pass NULL as root directory to
+ * chase_symlinks() here. */
+
+ r = chase_symlinks(mount_entry_source(m), NULL, CHASE_TRAIL_SLASH, &chased);
+ if (r == -ENOENT && m->ignore) {
+ log_debug_errno(r, "Path %s does not exist, ignoring.", mount_entry_source(m));
+ return 0;
+ }
+ if (r < 0)
+ return log_debug_errno(r, "Failed to follow symlinks on %s: %m", mount_entry_source(m));
+
+ log_debug("Followed source symlinks %s → %s.", mount_entry_source(m), chased);
+
+ free_and_replace(m->source_malloc, chased);
+
+ what = mount_entry_source(m);
+ make = true;
+ break;
+ }
+
+ case EMPTY_DIR:
+ case TMPFS:
+ return mount_tmpfs(m);
+
+ case PRIVATE_TMP:
+ what = mount_entry_source(m);
+ make = true;
+ break;
+
+ case PRIVATE_DEV:
+ return mount_private_dev(m);
+
+ case BIND_DEV:
+ return mount_bind_dev(m);
+
+ case SYSFS:
+ return mount_sysfs(m);
+
+ case PROCFS:
+ return mount_procfs(m);
+
+ default:
+ assert_not_reached("Unknown mode");
+ }
+
+ assert(what);
+
+ if (mount(what, mount_entry_path(m), NULL, MS_BIND|(rbind ? MS_REC : 0), NULL) < 0) {
+ bool try_again = false;
+ r = -errno;
+
+ if (r == -ENOENT && make) {
+ struct stat st;
+
+ /* Hmm, either the source or the destination are missing. Let's see if we can create the destination, then try again */
+
+ if (stat(what, &st) < 0)
+ log_debug_errno(errno, "Mount point source '%s' is not accessible: %m", what);
+ else {
+ int q;
+
+ (void) mkdir_parents(mount_entry_path(m), 0755);
+
+ if (S_ISDIR(st.st_mode))
+ q = mkdir(mount_entry_path(m), 0755) < 0 ? -errno : 0;
+ else
+ q = touch(mount_entry_path(m));
+
+ if (q < 0)
+ log_debug_errno(q, "Failed to create destination mount point node '%s': %m", mount_entry_path(m));
+ else
+ try_again = true;
+ }
+ }
+
+ if (try_again) {
+ if (mount(what, mount_entry_path(m), NULL, MS_BIND|(rbind ? MS_REC : 0), NULL) < 0)
+ r = -errno;
+ else
+ r = 0;
+ }
+
+ if (r < 0)
+ return log_debug_errno(r, "Failed to mount %s to %s: %m", what, mount_entry_path(m));
+ }
+
+ log_debug("Successfully mounted %s to %s", what, mount_entry_path(m));
+ return 0;
+}
+
+/* Change the per-mount readonly flag on an existing mount */
+static int remount_bind_readonly(const char *path, unsigned long orig_flags) {
+ int r;
+
+ r = mount(NULL, path, NULL, MS_REMOUNT | MS_BIND | MS_RDONLY | orig_flags, NULL);
+
+ return r < 0 ? -errno : 0;
+}
+
+static int make_read_only(const MountEntry *m, char **blacklist, FILE *proc_self_mountinfo) {
+ bool submounts = false;
+ int r = 0;
+
+ assert(m);
+ assert(proc_self_mountinfo);
+
+ if (mount_entry_read_only(m)) {
+ if (IN_SET(m->mode, EMPTY_DIR, TMPFS)) {
+ r = remount_bind_readonly(mount_entry_path(m), m->flags);
+ } else {
+ submounts = true;
+ r = bind_remount_recursive_with_mountinfo(mount_entry_path(m), true, blacklist, proc_self_mountinfo);
+ }
+ } else if (m->mode == PRIVATE_DEV) {
+ /* Set /dev readonly, but not submounts like /dev/shm. Also, we only set the per-mount read-only flag.
+ * We can't set it on the superblock, if we are inside a user namespace and running Linux <= 4.17. */
+ r = remount_bind_readonly(mount_entry_path(m), DEV_MOUNT_OPTIONS);
+ } else
+ return 0;
+
+ /* Not that we only turn on the MS_RDONLY flag here, we never turn it off. Something that was marked read-only
+ * already stays this way. This improves compatibility with container managers, where we won't attempt to undo
+ * read-only mounts already applied. */
+
+ if (r == -ENOENT && m->ignore)
+ r = 0;
+
+ if (r < 0)
+ return log_debug_errno(r, "Failed to re-mount '%s'%s read-only: %m", mount_entry_path(m),
+ submounts ? " and its submounts" : "");
+
+ return 0;
+}
+
+static bool namespace_info_mount_apivfs(const NamespaceInfo *ns_info) {
+ assert(ns_info);
+
+ /*
+ * ProtectControlGroups= and ProtectKernelTunables= imply MountAPIVFS=,
+ * since to protect the API VFS mounts, they need to be around in the
+ * first place...
+ */
+
+ return ns_info->mount_apivfs ||
+ ns_info->protect_control_groups ||
+ ns_info->protect_kernel_tunables;
+}
+
+static size_t namespace_calculate_mounts(
+ const NamespaceInfo *ns_info,
+ char** read_write_paths,
+ char** read_only_paths,
+ char** inaccessible_paths,
+ char** empty_directories,
+ size_t n_bind_mounts,
+ size_t n_temporary_filesystems,
+ const char* tmp_dir,
+ const char* var_tmp_dir,
+ ProtectHome protect_home,
+ ProtectSystem protect_system) {
+
+ size_t protect_home_cnt;
+ size_t protect_system_cnt =
+ (protect_system == PROTECT_SYSTEM_STRICT ?
+ ELEMENTSOF(protect_system_strict_table) :
+ ((protect_system == PROTECT_SYSTEM_FULL) ?
+ ELEMENTSOF(protect_system_full_table) :
+ ((protect_system == PROTECT_SYSTEM_YES) ?
+ ELEMENTSOF(protect_system_yes_table) : 0)));
+
+ protect_home_cnt =
+ (protect_home == PROTECT_HOME_YES ?
+ ELEMENTSOF(protect_home_yes_table) :
+ ((protect_home == PROTECT_HOME_READ_ONLY) ?
+ ELEMENTSOF(protect_home_read_only_table) :
+ ((protect_home == PROTECT_HOME_TMPFS) ?
+ ELEMENTSOF(protect_home_tmpfs_table) : 0)));
+
+ return !!tmp_dir + !!var_tmp_dir +
+ strv_length(read_write_paths) +
+ strv_length(read_only_paths) +
+ strv_length(inaccessible_paths) +
+ strv_length(empty_directories) +
+ n_bind_mounts +
+ n_temporary_filesystems +
+ ns_info->private_dev +
+ (ns_info->protect_kernel_tunables ? ELEMENTSOF(protect_kernel_tunables_table) : 0) +
+ (ns_info->protect_control_groups ? 1 : 0) +
+ (ns_info->protect_kernel_modules ? ELEMENTSOF(protect_kernel_modules_table) : 0) +
+ protect_home_cnt + protect_system_cnt +
+ (namespace_info_mount_apivfs(ns_info) ? ELEMENTSOF(apivfs_table) : 0);
+}
+
+static void normalize_mounts(const char *root_directory, MountEntry *mounts, size_t *n_mounts) {
+ assert(root_directory);
+ assert(n_mounts);
+ assert(mounts || *n_mounts == 0);
+
+ typesafe_qsort(mounts, *n_mounts, mount_path_compare);
+
+ drop_duplicates(mounts, n_mounts);
+ drop_outside_root(root_directory, mounts, n_mounts);
+ drop_inaccessible(mounts, n_mounts);
+ drop_nop(mounts, n_mounts);
+}
+
+int setup_namespace(
+ const char* root_directory,
+ const char* root_image,
+ const NamespaceInfo *ns_info,
+ char** read_write_paths,
+ char** read_only_paths,
+ char** inaccessible_paths,
+ char** empty_directories,
+ const BindMount *bind_mounts,
+ size_t n_bind_mounts,
+ const TemporaryFileSystem *temporary_filesystems,
+ size_t n_temporary_filesystems,
+ const char* tmp_dir,
+ const char* var_tmp_dir,
+ ProtectHome protect_home,
+ ProtectSystem protect_system,
+ unsigned long mount_flags,
+ DissectImageFlags dissect_image_flags) {
+
+ _cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL;
+ _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
+ _cleanup_(dissected_image_unrefp) DissectedImage *dissected_image = NULL;
+ _cleanup_free_ void *root_hash = NULL;
+ MountEntry *m, *mounts = NULL;
+ size_t n_mounts, root_hash_size = 0;
+ bool require_prefix = false;
+ const char *root;
+ int r = 0;
+
+ assert(ns_info);
+
+ if (mount_flags == 0)
+ mount_flags = MS_SHARED;
+
+ if (root_image) {
+ dissect_image_flags |= DISSECT_IMAGE_REQUIRE_ROOT;
+
+ if (protect_system == PROTECT_SYSTEM_STRICT &&
+ protect_home != PROTECT_HOME_NO &&
+ strv_isempty(read_write_paths))
+ dissect_image_flags |= DISSECT_IMAGE_READ_ONLY;
+
+ r = loop_device_make_by_path(root_image,
+ dissect_image_flags & DISSECT_IMAGE_READ_ONLY ? O_RDONLY : O_RDWR,
+ &loop_device);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to create loop device for root image: %m");
+
+ r = root_hash_load(root_image, &root_hash, &root_hash_size);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to load root hash: %m");
+
+ r = dissect_image(loop_device->fd, root_hash, root_hash_size, dissect_image_flags, &dissected_image);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to dissect image: %m");
+
+ r = dissected_image_decrypt(dissected_image, NULL, root_hash, root_hash_size, dissect_image_flags, &decrypted_image);
+ if (r < 0)
+ return log_debug_errno(r, "Failed to decrypt dissected image: %m");
+ }
+
+ if (root_directory)
+ root = root_directory;
+ else {
+ /* Always create the mount namespace in a temporary directory, instead of operating
+ * directly in the root. The temporary directory prevents any mounts from being
+ * potentially obscured my other mounts we already applied.
+ * We use the same mount point for all images, which is safe, since they all live
+ * in their own namespaces after all, and hence won't see each other. */
+
+ root = "/run/systemd/unit-root";
+ (void) mkdir_label(root, 0700);
+ require_prefix = true;
+ }
+
+ n_mounts = namespace_calculate_mounts(
+ ns_info,
+ read_write_paths,
+ read_only_paths,
+ inaccessible_paths,
+ empty_directories,
+ n_bind_mounts,
+ n_temporary_filesystems,
+ tmp_dir, var_tmp_dir,
+ protect_home, protect_system);
+
+ if (n_mounts > 0) {
+ m = mounts = (MountEntry *) alloca0(n_mounts * sizeof(MountEntry));
+ r = append_access_mounts(&m, read_write_paths, READWRITE, require_prefix);
+ if (r < 0)
+ goto finish;
+
+ r = append_access_mounts(&m, read_only_paths, READONLY, require_prefix);
+ if (r < 0)
+ goto finish;
+
+ r = append_access_mounts(&m, inaccessible_paths, INACCESSIBLE, require_prefix);
+ if (r < 0)
+ goto finish;
+
+ r = append_empty_dir_mounts(&m, empty_directories);
+ if (r < 0)
+ goto finish;
+
+ r = append_bind_mounts(&m, bind_mounts, n_bind_mounts);
+ if (r < 0)
+ goto finish;
+
+ r = append_tmpfs_mounts(&m, temporary_filesystems, n_temporary_filesystems);
+ if (r < 0)
+ goto finish;
+
+ if (tmp_dir) {
+ *(m++) = (MountEntry) {
+ .path_const = "/tmp",
+ .mode = PRIVATE_TMP,
+ .source_const = tmp_dir,
+ };
+ }
+
+ if (var_tmp_dir) {
+ *(m++) = (MountEntry) {
+ .path_const = "/var/tmp",
+ .mode = PRIVATE_TMP,
+ .source_const = var_tmp_dir,
+ };
+ }
+
+ if (ns_info->private_dev) {
+ *(m++) = (MountEntry) {
+ .path_const = "/dev",
+ .mode = PRIVATE_DEV,
+ };
+ }
+
+ if (ns_info->protect_kernel_tunables) {
+ r = append_static_mounts(&m, protect_kernel_tunables_table, ELEMENTSOF(protect_kernel_tunables_table), ns_info->ignore_protect_paths);
+ if (r < 0)
+ goto finish;
+ }
+
+ if (ns_info->protect_kernel_modules) {
+ r = append_static_mounts(&m, protect_kernel_modules_table, ELEMENTSOF(protect_kernel_modules_table), ns_info->ignore_protect_paths);
+ if (r < 0)
+ goto finish;
+ }
+
+ if (ns_info->protect_control_groups) {
+ *(m++) = (MountEntry) {
+ .path_const = "/sys/fs/cgroup",
+ .mode = READONLY,
+ };
+ }
+
+ r = append_protect_home(&m, protect_home, ns_info->ignore_protect_paths);
+ if (r < 0)
+ goto finish;
+
+ r = append_protect_system(&m, protect_system, false);
+ if (r < 0)
+ goto finish;
+
+ if (namespace_info_mount_apivfs(ns_info)) {
+ r = append_static_mounts(&m, apivfs_table, ELEMENTSOF(apivfs_table), ns_info->ignore_protect_paths);
+ if (r < 0)
+ goto finish;
+ }
+
+ assert(mounts + n_mounts == m);
+
+ /* Prepend the root directory where that's necessary */
+ r = prefix_where_needed(mounts, n_mounts, root);
+ if (r < 0)
+ goto finish;
+
+ normalize_mounts(root, mounts, &n_mounts);
+ }
+
+ /* All above is just preparation, figuring out what to do. Let's now actually start doing something. */
+
+ if (unshare(CLONE_NEWNS) < 0) {
+ r = log_debug_errno(errno, "Failed to unshare the mount namespace: %m");
+ if (IN_SET(r, -EACCES, -EPERM, -EOPNOTSUPP, -ENOSYS))
+ /* If the kernel doesn't support namespaces, or when there's a MAC or seccomp filter in place
+ * that doesn't allow us to create namespaces (or a missing cap), then propagate a recognizable
+ * error back, which the caller can use to detect this case (and only this) and optionally
+ * continue without namespacing applied. */
+ r = -ENOANO;
+
+ goto finish;
+ }
+
+ /* Remount / as SLAVE so that nothing now mounted in the namespace
+ * shows up in the parent */
+ if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) {
+ r = log_debug_errno(errno, "Failed to remount '/' as SLAVE: %m");
+ goto finish;
+ }
+
+ if (root_image) {
+ /* A root image is specified, mount it to the right place */
+ r = dissected_image_mount(dissected_image, root, UID_INVALID, dissect_image_flags);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to mount root image: %m");
+ goto finish;
+ }
+
+ if (decrypted_image) {
+ r = decrypted_image_relinquish(decrypted_image);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to relinquish decrypted image: %m");
+ goto finish;
+ }
+ }
+
+ loop_device_relinquish(loop_device);
+
+ } else if (root_directory) {
+
+ /* A root directory is specified. Turn its directory into bind mount, if it isn't one yet. */
+ r = path_is_mount_point(root, NULL, AT_SYMLINK_FOLLOW);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to detect that %s is a mount point or not: %m", root);
+ goto finish;
+ }
+ if (r == 0) {
+ if (mount(root, root, NULL, MS_BIND|MS_REC, NULL) < 0) {
+ r = log_debug_errno(errno, "Failed to bind mount '%s': %m", root);
+ goto finish;
+ }
+ }
+
+ } else {
+
+ /* Let's mount the main root directory to the root directory to use */
+ if (mount("/", root, NULL, MS_BIND|MS_REC, NULL) < 0) {
+ r = log_debug_errno(errno, "Failed to bind mount '/' on '%s': %m", root);
+ goto finish;
+ }
+ }
+
+ /* Try to set up the new root directory before mounting anything else there. */
+ if (root_image || root_directory)
+ (void) base_filesystem_create(root, UID_INVALID, GID_INVALID);
+
+ if (n_mounts > 0) {
+ _cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
+ char **blacklist;
+ size_t j;
+
+ /* Open /proc/self/mountinfo now as it may become unavailable if we mount anything on top of /proc.
+ * For example, this is the case with the option: 'InaccessiblePaths=/proc' */
+ proc_self_mountinfo = fopen("/proc/self/mountinfo", "re");
+ if (!proc_self_mountinfo) {
+ r = log_debug_errno(errno, "Failed to open /proc/self/mountinfo: %m");
+ goto finish;
+ }
+
+ /* First round, establish all mounts we need */
+ for (;;) {
+ bool again = false;
+
+ for (m = mounts; m < mounts + n_mounts; ++m) {
+
+ if (m->applied)
+ continue;
+
+ r = follow_symlink(root, m);
+ if (r < 0)
+ goto finish;
+ if (r == 0) {
+ /* We hit a symlinked mount point. The entry got rewritten and might point to a
+ * very different place now. Let's normalize the changed list, and start from
+ * the beginning. After all to mount the entry at the new location we might
+ * need some other mounts first */
+ again = true;
+ break;
+ }
+
+ r = apply_mount(root, m);
+ if (r < 0)
+ goto finish;
+
+ m->applied = true;
+ }
+
+ if (!again)
+ break;
+
+ normalize_mounts(root, mounts, &n_mounts);
+ }
+
+ /* Create a blacklist we can pass to bind_mount_recursive() */
+ blacklist = newa(char*, n_mounts+1);
+ for (j = 0; j < n_mounts; j++)
+ blacklist[j] = (char*) mount_entry_path(mounts+j);
+ blacklist[j] = NULL;
+
+ /* Second round, flip the ro bits if necessary. */
+ for (m = mounts; m < mounts + n_mounts; ++m) {
+ r = make_read_only(m, blacklist, proc_self_mountinfo);
+ if (r < 0)
+ goto finish;
+ }
+ }
+
+ /* MS_MOVE does not work on MS_SHARED so the remount MS_SHARED will be done later */
+ r = mount_move_root(root);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to mount root with MS_MOVE: %m");
+ goto finish;
+ }
+
+ /* Remount / as the desired mode. Note that this will not
+ * reestablish propagation from our side to the host, since
+ * what's disconnected is disconnected. */
+ if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
+ r = log_debug_errno(errno, "Failed to remount '/' with desired mount flags: %m");
+ goto finish;
+ }
+
+ r = 0;
+
+finish:
+ for (m = mounts; m < mounts + n_mounts; m++)
+ mount_entry_done(m);
+
+ return r;
+}
+
+void bind_mount_free_many(BindMount *b, size_t n) {
+ size_t i;
+
+ assert(b || n == 0);
+
+ for (i = 0; i < n; i++) {
+ free(b[i].source);
+ free(b[i].destination);
+ }
+
+ free(b);
+}
+
+int bind_mount_add(BindMount **b, size_t *n, const BindMount *item) {
+ _cleanup_free_ char *s = NULL, *d = NULL;
+ BindMount *c;
+
+ assert(b);
+ assert(n);
+ assert(item);
+
+ s = strdup(item->source);
+ if (!s)
+ return -ENOMEM;
+
+ d = strdup(item->destination);
+ if (!d)
+ return -ENOMEM;
+
+ c = reallocarray(*b, *n + 1, sizeof(BindMount));
+ if (!c)
+ return -ENOMEM;
+
+ *b = c;
+
+ c[(*n) ++] = (BindMount) {
+ .source = TAKE_PTR(s),
+ .destination = TAKE_PTR(d),
+ .read_only = item->read_only,
+ .recursive = item->recursive,
+ .ignore_enoent = item->ignore_enoent,
+ };
+
+ return 0;
+}
+
+void temporary_filesystem_free_many(TemporaryFileSystem *t, size_t n) {
+ size_t i;
+
+ assert(t || n == 0);
+
+ for (i = 0; i < n; i++) {
+ free(t[i].path);
+ free(t[i].options);
+ }
+
+ free(t);
+}
+
+int temporary_filesystem_add(
+ TemporaryFileSystem **t,
+ size_t *n,
+ const char *path,
+ const char *options) {
+
+ _cleanup_free_ char *p = NULL, *o = NULL;
+ TemporaryFileSystem *c;
+
+ assert(t);
+ assert(n);
+ assert(path);
+
+ p = strdup(path);
+ if (!p)
+ return -ENOMEM;
+
+ if (!isempty(options)) {
+ o = strdup(options);
+ if (!o)
+ return -ENOMEM;
+ }
+
+ c = reallocarray(*t, *n + 1, sizeof(TemporaryFileSystem));
+ if (!c)
+ return -ENOMEM;
+
+ *t = c;
+
+ c[(*n) ++] = (TemporaryFileSystem) {
+ .path = TAKE_PTR(p),
+ .options = TAKE_PTR(o),
+ };
+
+ return 0;
+}
+
+static int setup_one_tmp_dir(const char *id, const char *prefix, char **path) {
+ _cleanup_free_ char *x = NULL;
+ char bid[SD_ID128_STRING_MAX];
+ sd_id128_t boot_id;
+ int r;
+
+ assert(id);
+ assert(prefix);
+ assert(path);
+
+ /* We include the boot id in the directory so that after a
+ * reboot we can easily identify obsolete directories. */
+
+ r = sd_id128_get_boot(&boot_id);
+ if (r < 0)
+ return r;
+
+ x = strjoin(prefix, "/systemd-private-", sd_id128_to_string(boot_id, bid), "-", id, "-XXXXXX");
+ if (!x)
+ return -ENOMEM;
+
+ RUN_WITH_UMASK(0077)
+ if (!mkdtemp(x))
+ return -errno;
+
+ RUN_WITH_UMASK(0000) {
+ char *y;
+
+ y = strjoina(x, "/tmp");
+
+ if (mkdir(y, 0777 | S_ISVTX) < 0)
+ return -errno;
+ }
+
+ *path = TAKE_PTR(x);
+
+ return 0;
+}
+
+int setup_tmp_dirs(const char *id, char **tmp_dir, char **var_tmp_dir) {
+ char *a, *b;
+ int r;
+
+ assert(id);
+ assert(tmp_dir);
+ assert(var_tmp_dir);
+
+ r = setup_one_tmp_dir(id, "/tmp", &a);
+ if (r < 0)
+ return r;
+
+ r = setup_one_tmp_dir(id, "/var/tmp", &b);
+ if (r < 0) {
+ char *t;
+
+ t = strjoina(a, "/tmp");
+ rmdir(t);
+ rmdir(a);
+
+ free(a);
+ return r;
+ }
+
+ *tmp_dir = a;
+ *var_tmp_dir = b;
+
+ return 0;
+}
+
+int setup_netns(int netns_storage_socket[static 2]) {
+ _cleanup_close_ int netns = -1;
+ int r, q;
+
+ assert(netns_storage_socket);
+ assert(netns_storage_socket[0] >= 0);
+ assert(netns_storage_socket[1] >= 0);
+
+ /* We use the passed socketpair as a storage buffer for our
+ * namespace reference fd. Whatever process runs this first
+ * shall create a new namespace, all others should just join
+ * it. To serialize that we use a file lock on the socket
+ * pair.
+ *
+ * It's a bit crazy, but hey, works great! */
+
+ if (lockf(netns_storage_socket[0], F_LOCK, 0) < 0)
+ return -errno;
+
+ netns = receive_one_fd(netns_storage_socket[0], MSG_DONTWAIT);
+ if (netns == -EAGAIN) {
+ /* Nothing stored yet, so let's create a new namespace */
+
+ if (unshare(CLONE_NEWNET) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ loopback_setup();
+
+ netns = open("/proc/self/ns/net", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (netns < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = 1;
+
+ } else if (netns < 0) {
+ r = netns;
+ goto fail;
+
+ } else {
+ /* Yay, found something, so let's join the namespace */
+ if (setns(netns, CLONE_NEWNET) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = 0;
+ }
+
+ q = send_one_fd(netns_storage_socket[1], netns, MSG_DONTWAIT);
+ if (q < 0) {
+ r = q;
+ goto fail;
+ }
+
+fail:
+ (void) lockf(netns_storage_socket[0], F_ULOCK, 0);
+ return r;
+}
+
+bool ns_type_supported(NamespaceType type) {
+ const char *t, *ns_proc;
+
+ t = namespace_type_to_string(type);
+ if (!t) /* Don't know how to translate this? Then it's not supported */
+ return false;
+
+ ns_proc = strjoina("/proc/self/ns/", t);
+ return access(ns_proc, F_OK) == 0;
+}
+
+static const char *const protect_home_table[_PROTECT_HOME_MAX] = {
+ [PROTECT_HOME_NO] = "no",
+ [PROTECT_HOME_YES] = "yes",
+ [PROTECT_HOME_READ_ONLY] = "read-only",
+ [PROTECT_HOME_TMPFS] = "tmpfs",
+};
+
+DEFINE_STRING_TABLE_LOOKUP_WITH_BOOLEAN(protect_home, ProtectHome, PROTECT_HOME_YES);
+
+static const char *const protect_system_table[_PROTECT_SYSTEM_MAX] = {
+ [PROTECT_SYSTEM_NO] = "no",
+ [PROTECT_SYSTEM_YES] = "yes",
+ [PROTECT_SYSTEM_FULL] = "full",
+ [PROTECT_SYSTEM_STRICT] = "strict",
+};
+
+DEFINE_STRING_TABLE_LOOKUP_WITH_BOOLEAN(protect_system, ProtectSystem, PROTECT_SYSTEM_YES);
+
+static const char* const namespace_type_table[] = {
+ [NAMESPACE_MOUNT] = "mnt",
+ [NAMESPACE_CGROUP] = "cgroup",
+ [NAMESPACE_UTS] = "uts",
+ [NAMESPACE_IPC] = "ipc",
+ [NAMESPACE_USER] = "user",
+ [NAMESPACE_PID] = "pid",
+ [NAMESPACE_NET] = "net",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(namespace_type, NamespaceType);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 18:38:21 +0000