diff options
Diffstat (limited to 'src/core/namespace.c')
| -rw-r--r-- | src/core/namespace.c | 3047 |
1 files changed, 3047 insertions, 0 deletions
diff --git a/src/core/namespace.c b/src/core/namespace.c new file mode 100644 index 0000000..88681aa --- /dev/null +++ b/src/core/namespace.c @@ -0,0 +1,3047 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <errno.h> +#include <linux/loop.h> +#include <sched.h> +#include <stdio.h> +#include <sys/file.h> +#include <sys/mount.h> +#include <unistd.h> +#if WANT_LINUX_FS_H +#include <linux/fs.h> +#endif + +#include "alloc-util.h" +#include "base-filesystem.h" +#include "chase.h" +#include "dev-setup.h" +#include "devnum-util.h" +#include "env-util.h" +#include "escape.h" +#include "extension-util.h" +#include "fd-util.h" +#include "format-util.h" +#include "glyph-util.h" +#include "label-util.h" +#include "list.h" +#include "lock-util.h" +#include "loop-util.h" +#include "loopback-setup.h" +#include "missing_syscall.h" +#include "mkdir-label.h" +#include "mount-util.h" +#include "mountpoint-util.h" +#include "namespace-util.h" +#include "namespace.h" +#include "nsflags.h" +#include "nulstr-util.h" +#include "os-util.h" +#include "path-util.h" +#include "selinux-util.h" +#include "socket-util.h" +#include "sort-util.h" +#include "stat-util.h" +#include "string-table.h" +#include "string-util.h" +#include "strv.h" +#include "tmpfile-util.h" +#include "umask-util.h" +#include "user-util.h" + +#define DEV_MOUNT_OPTIONS (MS_NOSUID|MS_STRICTATIME|MS_NOEXEC) + +typedef enum MountMode { + /* This is ordered by priority! */ + MOUNT_INACCESSIBLE, + MOUNT_OVERLAY, + MOUNT_IMAGE, + MOUNT_BIND, + MOUNT_BIND_RECURSIVE, + MOUNT_PRIVATE_TMP, + MOUNT_PRIVATE_TMP_READ_ONLY, + MOUNT_PRIVATE_DEV, + MOUNT_BIND_DEV, + MOUNT_EMPTY_DIR, + MOUNT_PRIVATE_SYSFS, + MOUNT_BIND_SYSFS, + MOUNT_PROCFS, + MOUNT_READ_ONLY, + MOUNT_READ_WRITE, + MOUNT_NOEXEC, + MOUNT_EXEC, + MOUNT_TMPFS, + MOUNT_RUN, + MOUNT_EXTENSION_DIRECTORY, /* Bind-mounted outside the root directory, and used by subsequent mounts */ + MOUNT_EXTENSION_IMAGE, /* Mounted outside the root directory, and used by subsequent mounts */ + MOUNT_MQUEUEFS, + MOUNT_READ_WRITE_IMPLICIT, /* Should have the lowest priority. */ + _MOUNT_MODE_MAX, + _MOUNT_MODE_INVALID = -EINVAL, +} MountMode; + +typedef enum MountEntryState { + MOUNT_PENDING, + MOUNT_APPLIED, + MOUNT_SKIPPED, + _MOUNT_ENTRY_STATE_MAX, + _MOUNT_ENTRY_STATE_INVALID = -EINVAL, +} MountEntryState; + +typedef struct MountEntry { + const char *path_const; /* Memory allocated on stack or static */ + MountMode mode; + 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 nosuid:1; /* Shall set MS_NOSUID on the mount itself */ + bool noexec:1; /* Shall set MS_NOEXEC on the mount itself */ + bool exec:1; /* Shall clear MS_NOEXEC on the mount itself */ + MountEntryState state; /* Whether it was already processed or skipped */ + char *path_malloc; /* Use this instead of 'path_const' if we had to allocate memory */ + const char *unprefixed_path_const; /* If the path was amended with a prefix, these will save the original */ + char *unprefixed_path_malloc; + const char *source_const; /* The source path, for bind mounts or images */ + 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; + LIST_HEAD(MountOptions, image_options_const); + char **overlay_layers; +} MountEntry; + +typedef struct MountList { + MountEntry *mounts; + size_t n_mounts; +} MountList; + +/* If MountAPIVFS= is used, let's mount /sys, /proc, /dev and /run 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", MOUNT_PROCFS, false }, + { "/dev", MOUNT_BIND_DEV, false }, + { "/sys", MOUNT_BIND_SYSFS, false }, + { "/run", MOUNT_RUN, false, .options_const = "mode=0755" TMPFS_LIMITS_RUN, .flags = MS_NOSUID|MS_NODEV|MS_STRICTATIME }, +}; + +/* ProtectKernelTunables= option and the related filesystem APIs */ +static const MountEntry protect_kernel_tunables_proc_table[] = { + { "/proc/acpi", MOUNT_READ_ONLY, true }, + { "/proc/apm", MOUNT_READ_ONLY, true }, /* Obsolete API, there's no point in permitting access to this, ever */ + { "/proc/asound", MOUNT_READ_ONLY, true }, + { "/proc/bus", MOUNT_READ_ONLY, true }, + { "/proc/fs", MOUNT_READ_ONLY, true }, + { "/proc/irq", MOUNT_READ_ONLY, true }, + { "/proc/kallsyms", MOUNT_INACCESSIBLE, true }, + { "/proc/kcore", MOUNT_INACCESSIBLE, true }, + { "/proc/latency_stats", MOUNT_READ_ONLY, true }, + { "/proc/mtrr", MOUNT_READ_ONLY, true }, + { "/proc/scsi", MOUNT_READ_ONLY, true }, + { "/proc/sys", MOUNT_READ_ONLY, true }, + { "/proc/sysrq-trigger", MOUNT_READ_ONLY, true }, + { "/proc/timer_stats", MOUNT_READ_ONLY, true }, +}; + +static const MountEntry protect_kernel_tunables_sys_table[] = { + { "/sys", MOUNT_READ_ONLY, false }, + { "/sys/fs/bpf", MOUNT_READ_ONLY, true }, + { "/sys/fs/cgroup", MOUNT_READ_WRITE_IMPLICIT, false }, /* READ_ONLY is set by ProtectControlGroups= option */ + { "/sys/fs/selinux", MOUNT_READ_WRITE_IMPLICIT, true }, + { "/sys/kernel/debug", MOUNT_READ_ONLY, true }, + { "/sys/kernel/tracing", MOUNT_READ_ONLY, true }, +}; + +/* ProtectKernelModules= option */ +static const MountEntry protect_kernel_modules_table[] = { + { "/usr/lib/modules", MOUNT_INACCESSIBLE, true }, +}; + +/* ProtectKernelLogs= option */ +static const MountEntry protect_kernel_logs_proc_table[] = { + { "/proc/kmsg", MOUNT_INACCESSIBLE, true }, +}; + +static const MountEntry protect_kernel_logs_dev_table[] = { + { "/dev/kmsg", MOUNT_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", MOUNT_READ_ONLY, true }, + { "/run/user", MOUNT_READ_ONLY, true }, + { "/root", MOUNT_READ_ONLY, true }, +}; + +/* ProtectHome=tmpfs table */ +static const MountEntry protect_home_tmpfs_table[] = { + { "/home", MOUNT_TMPFS, true, .read_only = true, .options_const = "mode=0755" TMPFS_LIMITS_EMPTY_OR_ALMOST, .flags = MS_NODEV|MS_STRICTATIME }, + { "/run/user", MOUNT_TMPFS, true, .read_only = true, .options_const = "mode=0755" TMPFS_LIMITS_EMPTY_OR_ALMOST, .flags = MS_NODEV|MS_STRICTATIME }, + { "/root", MOUNT_TMPFS, true, .read_only = true, .options_const = "mode=0700" TMPFS_LIMITS_EMPTY_OR_ALMOST, .flags = MS_NODEV|MS_STRICTATIME }, +}; + +/* ProtectHome=yes table */ +static const MountEntry protect_home_yes_table[] = { + { "/home", MOUNT_INACCESSIBLE, true }, + { "/run/user", MOUNT_INACCESSIBLE, true }, + { "/root", MOUNT_INACCESSIBLE, true }, +}; + +/* ProtectSystem=yes table */ +static const MountEntry protect_system_yes_table[] = { + { "/usr", MOUNT_READ_ONLY, false }, + { "/boot", MOUNT_READ_ONLY, true }, + { "/efi", MOUNT_READ_ONLY, true }, +}; + +/* ProtectSystem=full includes ProtectSystem=yes */ +static const MountEntry protect_system_full_table[] = { + { "/usr", MOUNT_READ_ONLY, false }, + { "/boot", MOUNT_READ_ONLY, true }, + { "/efi", MOUNT_READ_ONLY, true }, + { "/etc", MOUNT_READ_ONLY, false }, +}; + +/* 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[] = { + { "/", MOUNT_READ_ONLY, false }, + { "/proc", MOUNT_READ_WRITE_IMPLICIT, false }, /* ProtectKernelTunables= */ + { "/sys", MOUNT_READ_WRITE_IMPLICIT, false }, /* ProtectKernelTunables= */ + { "/dev", MOUNT_READ_WRITE_IMPLICIT, false }, /* PrivateDevices= */ + { "/home", MOUNT_READ_WRITE_IMPLICIT, true }, /* ProtectHome= */ + { "/run/user", MOUNT_READ_WRITE_IMPLICIT, true }, /* ProtectHome= */ + { "/root", MOUNT_READ_WRITE_IMPLICIT, true }, /* ProtectHome= */ +}; + +/* ProtectHostname=yes able */ +static const MountEntry protect_hostname_table[] = { + { "/proc/sys/kernel/hostname", MOUNT_READ_ONLY, false }, + { "/proc/sys/kernel/domainname", MOUNT_READ_ONLY, false }, +}; + +static const char * const mount_mode_table[_MOUNT_MODE_MAX] = { + [MOUNT_INACCESSIBLE] = "inaccessible", + [MOUNT_OVERLAY] = "overlay", + [MOUNT_IMAGE] = "image", + [MOUNT_BIND] = "bind", + [MOUNT_BIND_RECURSIVE] = "bind-recursive", + [MOUNT_PRIVATE_TMP] = "private-tmp", + [MOUNT_PRIVATE_TMP_READ_ONLY] = "private-tmp-read-only", + [MOUNT_PRIVATE_DEV] = "private-dev", + [MOUNT_BIND_DEV] = "bind-dev", + [MOUNT_EMPTY_DIR] = "empty-dir", + [MOUNT_PRIVATE_SYSFS] = "private-sysfs", + [MOUNT_BIND_SYSFS] = "bind-sysfs", + [MOUNT_PROCFS] = "procfs", + [MOUNT_READ_ONLY] = "read-only", + [MOUNT_READ_WRITE] = "read-write", + [MOUNT_NOEXEC] = "noexec", + [MOUNT_EXEC] = "exec", + [MOUNT_TMPFS] = "tmpfs", + [MOUNT_RUN] = "run", + [MOUNT_EXTENSION_DIRECTORY] = "extension-directory", + [MOUNT_EXTENSION_IMAGE] = "extension-image", + [MOUNT_MQUEUEFS] = "mqueuefs", + [MOUNT_READ_WRITE_IMPLICIT] = "read-write-implicit", +}; + +/* Helper struct for naming simplicity and reusability */ +static const struct { + const char *level_env; + const char *level_env_print; +} image_class_info[_IMAGE_CLASS_MAX] = { + [IMAGE_SYSEXT] = { + .level_env = "SYSEXT_LEVEL", + .level_env_print = " SYSEXT_LEVEL=", + }, + [IMAGE_CONFEXT] = { + .level_env = "CONFEXT_LEVEL", + .level_env_print = " CONFEXT_LEVEL=", + } +}; + +DEFINE_PRIVATE_STRING_TABLE_LOOKUP_TO_STRING(mount_mode, MountMode); + +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 const char *mount_entry_unprefixed_path(const MountEntry *p) { + assert(p); + + /* Returns the unprefixed path (ie: before prefix_where_needed() ran), if any */ + + return p->unprefixed_path_malloc ?: p->unprefixed_path_const ?: mount_entry_path(p); +} + +static void mount_entry_consume_prefix(MountEntry *p, char *new_path) { + assert(p); + assert(p->path_malloc || p->path_const); + assert(new_path); + + /* Saves current path in unprefixed_ variable, and takes over new_path */ + + free_and_replace(p->unprefixed_path_malloc, p->path_malloc); + /* If we didn't have a path on the heap, then it's a static one */ + if (!p->unprefixed_path_malloc) + p->unprefixed_path_const = p->path_const; + p->path_malloc = new_path; + p->has_prefix = true; +} + +static bool mount_entry_read_only(const MountEntry *p) { + assert(p); + + return p->read_only || IN_SET(p->mode, MOUNT_READ_ONLY, MOUNT_INACCESSIBLE, MOUNT_PRIVATE_TMP_READ_ONLY); +} + +static bool mount_entry_noexec(const MountEntry *p) { + assert(p); + + return p->noexec || IN_SET(p->mode, MOUNT_NOEXEC, MOUNT_INACCESSIBLE, MOUNT_PRIVATE_SYSFS, MOUNT_BIND_SYSFS, MOUNT_PROCFS); +} + +static bool mount_entry_exec(const MountEntry *p) { + assert(p); + + return p->exec || p->mode == MOUNT_EXEC; +} + +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->unprefixed_path_malloc = mfree(p->unprefixed_path_malloc); + p->source_malloc = mfree(p->source_malloc); + p->options_malloc = mfree(p->options_malloc); + p->overlay_layers = strv_free(p->overlay_layers); +} + +static void mount_list_done(MountList *ml) { + assert(ml); + + FOREACH_ARRAY(m, ml->mounts, ml->n_mounts) + mount_entry_done(m); + + ml->mounts = mfree(ml->mounts); + ml->n_mounts = 0; +} + +static MountEntry *mount_list_extend(MountList *ml) { + assert(ml); + + if (!GREEDY_REALLOC0(ml->mounts, ml->n_mounts+1)) + return NULL; + + return ml->mounts + ml->n_mounts++; +} + +static int append_access_mounts(MountList *ml, char **strv, MountMode mode, bool forcibly_require_prefix) { + assert(ml); + + /* Adds a list of user-supplied READ_WRITE/READ_WRITE_IMPLICIT/READ_ONLY/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); + + MountEntry *me = mount_list_extend(ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = e, + .mode = mode, + .ignore = ignore, + .has_prefix = !needs_prefix && !forcibly_require_prefix, + }; + } + + return 0; +} + +static int append_empty_dir_mounts(MountList *ml, char **strv) { + assert(ml); + + /* 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) { + MountEntry *me = mount_list_extend(ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = *i, + .mode = MOUNT_EMPTY_DIR, + .ignore = false, + .read_only = true, + .options_const = "mode=0755" TMPFS_LIMITS_EMPTY_OR_ALMOST, + .flags = MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, + }; + } + + return 0; +} + +static int append_bind_mounts(MountList *ml, const BindMount *binds, size_t n) { + assert(ml); + assert(binds || n == 0); + + FOREACH_ARRAY(b, binds, n) { + MountEntry *me = mount_list_extend(ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = b->destination, + .mode = b->recursive ? MOUNT_BIND_RECURSIVE : MOUNT_BIND, + .read_only = b->read_only, + .nosuid = b->nosuid, + .source_const = b->source, + .ignore = b->ignore_enoent, + }; + } + + return 0; +} + +static int append_mount_images(MountList *ml, const MountImage *mount_images, size_t n) { + assert(ml); + assert(mount_images || n == 0); + + FOREACH_ARRAY(m, mount_images, n) { + MountEntry *me = mount_list_extend(ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = m->destination, + .mode = MOUNT_IMAGE, + .source_const = m->source, + .image_options_const = m->mount_options, + .ignore = m->ignore_enoent, + }; + } + + return 0; +} + +static int append_extensions( + MountList *ml, + const char *root, + const char *extension_dir, + char **hierarchies, + const MountImage *mount_images, + size_t n, + char **extension_directories) { + + char ***overlays = NULL; + size_t n_overlays = 0; + int r; + + assert(ml); + + if (n == 0 && strv_isempty(extension_directories)) + return 0; + + assert(extension_dir); + + n_overlays = strv_length(hierarchies); + if (n_overlays == 0) + return 0; + + /* Prepare a list of overlays, that will have as each element a strv containing all the layers that + * will later be concatenated as a lowerdir= parameter for the mount operation. + * The overlays vector will have the same number of elements and will correspond to the + * hierarchies vector, so they can be iterated upon together. */ + overlays = new0(char**, n_overlays); + if (!overlays) + return -ENOMEM; + + CLEANUP_ARRAY(overlays, n_overlays, strv_free_many); + + /* First, prepare a mount for each image, but these won't be visible to the unit, instead + * they will be mounted in our propagate directory, and used as a source for the overlay. */ + for (size_t i = 0; i < n; i++) { + _cleanup_free_ char *mount_point = NULL; + const MountImage *m = mount_images + i; + + if (asprintf(&mount_point, "%s/%zu", extension_dir, i) < 0) + return -ENOMEM; + + for (size_t j = 0; hierarchies && hierarchies[j]; ++j) { + char *prefixed_hierarchy = path_join(mount_point, hierarchies[j]); + if (!prefixed_hierarchy) + return -ENOMEM; + + r = strv_consume(&overlays[j], TAKE_PTR(prefixed_hierarchy)); + if (r < 0) + return r; + } + + MountEntry *me = mount_list_extend(ml); + if (!me) + return -ENOMEM; + + *me = (MountEntry) { + .path_malloc = TAKE_PTR(mount_point), + .image_options_const = m->mount_options, + .ignore = m->ignore_enoent, + .source_const = m->source, + .mode = MOUNT_EXTENSION_IMAGE, + .has_prefix = true, + }; + } + + /* Secondly, extend the lowerdir= parameters with each ExtensionDirectory. + * Bind mount them in the same location as the ExtensionImages, so that we + * can check that they are valid trees (extension-release.d). */ + STRV_FOREACH(extension_directory, extension_directories) { + _cleanup_free_ char *mount_point = NULL, *source = NULL; + const char *e = *extension_directory; + bool ignore_enoent = false; + + /* Pick up the counter where the ExtensionImages left it. */ + if (asprintf(&mount_point, "%s/%zu", extension_dir, n++) < 0) + return -ENOMEM; + + /* Look for any prefixes */ + if (startswith(e, "-")) { + e++; + ignore_enoent = true; + } + /* Ignore this for now */ + if (startswith(e, "+")) + e++; + + source = strdup(e); + if (!source) + return -ENOMEM; + + for (size_t j = 0; hierarchies && hierarchies[j]; ++j) { + char *prefixed_hierarchy = path_join(mount_point, hierarchies[j]); + if (!prefixed_hierarchy) + return -ENOMEM; + + r = strv_consume(&overlays[j], TAKE_PTR(prefixed_hierarchy)); + if (r < 0) + return r; + } + + MountEntry *me = mount_list_extend(ml); + if (!me) + return -ENOMEM; + + *me = (MountEntry) { + .path_malloc = TAKE_PTR(mount_point), + .source_malloc = TAKE_PTR(source), + .mode = MOUNT_EXTENSION_DIRECTORY, + .ignore = ignore_enoent, + .has_prefix = true, + .read_only = true, + }; + } + + /* Then, for each hierarchy, prepare an overlay with the list of lowerdir= strings + * set up earlier. */ + for (size_t i = 0; hierarchies && hierarchies[i]; ++i) { + _cleanup_free_ char *prefixed_hierarchy = NULL; + + prefixed_hierarchy = path_join(root, hierarchies[i]); + if (!prefixed_hierarchy) + return -ENOMEM; + + MountEntry *me = mount_list_extend(ml); + if (!me) + return -ENOMEM; + + *me = (MountEntry) { + .path_malloc = TAKE_PTR(prefixed_hierarchy), + .overlay_layers = TAKE_PTR(overlays[i]), + .mode = MOUNT_OVERLAY, + .has_prefix = true, + .ignore = true, /* If the source image doesn't set the ignore bit it will fail earlier. */ + }; + } + + return 0; +} + +static int append_tmpfs_mounts(MountList *ml, const TemporaryFileSystem *tmpfs, size_t n) { + assert(ml); + assert(tmpfs || n == 0); + + FOREACH_ARRAY(t, tmpfs, n) { + _cleanup_free_ char *o = NULL, *str = NULL; + unsigned long flags; + bool ro = false; + int r; + + if (!path_is_absolute(t->path)) + return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Path is not absolute: %s", t->path); + + str = strjoin("mode=0755" NESTED_TMPFS_LIMITS ",", 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; + + MountEntry *me = mount_list_extend(ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = t->path, + .mode = MOUNT_TMPFS, + .read_only = ro, + .options_malloc = TAKE_PTR(o), + .flags = flags, + }; + } + + return 0; +} + +static int append_static_mounts(MountList *ml, const MountEntry *mounts, size_t n, bool ignore_protect) { + assert(ml); + assert(mounts || n == 0); + + /* Adds a list of static pre-defined entries */ + + FOREACH_ARRAY(m, mounts, n) { + MountEntry *me = mount_list_extend(ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = mount_entry_path(m), + .mode = m->mode, + .ignore = m->ignore || ignore_protect, + }; + } + + return 0; +} + +static int append_protect_home(MountList *ml, ProtectHome protect_home, bool ignore_protect) { + assert(ml); + + switch (protect_home) { + + case PROTECT_HOME_NO: + return 0; + + case PROTECT_HOME_READ_ONLY: + return append_static_mounts(ml, protect_home_read_only_table, ELEMENTSOF(protect_home_read_only_table), ignore_protect); + + case PROTECT_HOME_TMPFS: + return append_static_mounts(ml, protect_home_tmpfs_table, ELEMENTSOF(protect_home_tmpfs_table), ignore_protect); + + case PROTECT_HOME_YES: + return append_static_mounts(ml, protect_home_yes_table, ELEMENTSOF(protect_home_yes_table), ignore_protect); + + default: + assert_not_reached(); + } +} + +static int append_protect_system(MountList *ml, ProtectSystem protect_system, bool ignore_protect) { + assert(ml); + + switch (protect_system) { + + case PROTECT_SYSTEM_NO: + return 0; + + case PROTECT_SYSTEM_STRICT: + return append_static_mounts(ml, protect_system_strict_table, ELEMENTSOF(protect_system_strict_table), ignore_protect); + + case PROTECT_SYSTEM_YES: + return append_static_mounts(ml, protect_system_yes_table, ELEMENTSOF(protect_system_yes_table), ignore_protect); + + case PROTECT_SYSTEM_FULL: + return append_static_mounts(ml, protect_system_full_table, ELEMENTSOF(protect_system_full_table), ignore_protect); + + default: + assert_not_reached(); + } +} + +static int mount_path_compare(const MountEntry *a, const MountEntry *b) { + int d; + + /* ExtensionImages/Directories will be used by other mounts as a base, so sort them first + * regardless of the prefix - they are set up in the propagate directory anyway */ + d = -CMP(a->mode == MOUNT_EXTENSION_IMAGE, b->mode == MOUNT_EXTENSION_IMAGE); + if (d != 0) + return d; + d = -CMP(a->mode == MOUNT_EXTENSION_DIRECTORY, b->mode == MOUNT_EXTENSION_DIRECTORY); + if (d != 0) + return 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(MountList *ml, const char *root_directory) { + /* Prefixes all paths in the bind mount table with the root directory if the entry needs that. */ + + assert(ml); + + FOREACH_ARRAY(me, ml->mounts, ml->n_mounts) { + char *s; + + if (me->has_prefix) + continue; + + s = path_join(root_directory, mount_entry_path(me)); + if (!s) + return -ENOMEM; + + mount_entry_consume_prefix(me, s); + } + + return 0; +} + +static void drop_duplicates(MountList *ml) { + MountEntry *f, *t, *previous; + + assert(ml); + + /* Drops duplicate entries. Expects that the array is properly ordered already. */ + + for (f = ml->mounts, t = ml->mounts, previous = NULL; f < ml->mounts + ml->n_mounts; 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->state == MOUNT_PENDING && previous->state == MOUNT_PENDING) { + log_debug("%s (%s) is duplicate.", mount_entry_path(f), mount_mode_to_string(f->mode)); + /* Propagate the flags to the remaining entry */ + previous->read_only = previous->read_only || mount_entry_read_only(f); + previous->noexec = previous->noexec || mount_entry_noexec(f); + previous->exec = previous->exec || mount_entry_exec(f); + mount_entry_done(f); + continue; + } + + *t = *f; + previous = t; + t++; + } + + ml->n_mounts = t - ml->mounts; +} + +static void drop_inaccessible(MountList *ml) { + MountEntry *f, *t; + const char *clear = NULL; + + assert(ml); + + /* Drops all entries obstructed by another entry further up the tree. Expects that the array is properly + * ordered already. */ + + for (f = ml->mounts, t = ml->mounts; f < ml->mounts + ml->n_mounts; 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 == MOUNT_INACCESSIBLE ? mount_entry_path(f) : NULL; + + *t = *f; + t++; + } + + ml->n_mounts = t - ml->mounts; +} + +static void drop_nop(MountList *ml) { + MountEntry *f, *t; + + assert(ml); + + /* 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 = ml->mounts, t = ml->mounts; f < ml->mounts + ml->n_mounts; f++) { + + /* Only suppress such subtrees for READ_ONLY, READ_WRITE and READ_WRITE_IMPLICIT entries */ + if (IN_SET(f->mode, MOUNT_READ_ONLY, MOUNT_READ_WRITE, MOUNT_READ_WRITE_IMPLICIT)) { + MountEntry *found = NULL; + + /* Now let's find the first parent of the entry we are looking at. */ + for (MountEntry *p = PTR_SUB1(t, ml->mounts); p; p = PTR_SUB1(p, ml->mounts)) + if (path_startswith(mount_entry_path(f), mount_entry_path(p))) { + found = p; + break; + } + + /* We found it, let's see if it's the same mode, if so, we can drop this entry */ + if (found && found->mode == f->mode) { + log_debug("%s (%s) is made redundant by %s (%s)", + mount_entry_path(f), mount_mode_to_string(f->mode), + mount_entry_path(found), mount_mode_to_string(found->mode)); + mount_entry_done(f); + continue; + } + } + + *t = *f; + t++; + } + + ml->n_mounts = t - ml->mounts; +} + +static void drop_outside_root(MountList *ml, const char *root_directory) { + MountEntry *f, *t; + + assert(ml); + + /* Nothing to do */ + if (!root_directory) + return; + + /* Drops all mounts that are outside of the root directory. */ + + for (f = ml->mounts, t = ml->mounts; f < ml->mounts + ml->n_mounts; f++) { + + /* ExtensionImages/Directories bases are opened in /run/systemd/unit-extensions on the host */ + if (!IN_SET(f->mode, MOUNT_EXTENSION_IMAGE, MOUNT_EXTENSION_DIRECTORY) && !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++; + } + + ml->n_mounts = t - ml->mounts; +} + +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 fall back to bind-mounting the device node. So create a dummy bind-mount target. + * Do not prepare device-node SELinux label (see issue 13762) */ + r = mknod(dn, S_IFREG, 0); + 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. */ + r = mount_nofollow_verbose(LOG_DEBUG, d, dn, NULL, MS_BIND, NULL); + if (r < 0) + return r; + +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/" DEVNUM_FORMAT_STR, + temporary_mount, + S_ISCHR(st.st_mode) ? "char" : "block", + DEVNUM_FORMAT_VAL(st.st_rdev)) < 0) + return log_oom_debug(); + + (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 char *settle_runtime_dir(RuntimeScope scope) { + char *runtime_dir; + + if (scope != RUNTIME_SCOPE_USER) + return strdup("/run/"); + + if (asprintf(&runtime_dir, "/run/user/" UID_FMT, geteuid()) < 0) + return NULL; + + return runtime_dir; +} + +static int create_temporary_mount_point(RuntimeScope scope, char **ret) { + _cleanup_free_ char *runtime_dir = NULL, *temporary_mount = NULL; + + assert(ret); + + runtime_dir = settle_runtime_dir(scope); + if (!runtime_dir) + return log_oom_debug(); + + temporary_mount = path_join(runtime_dir, "systemd/namespace-XXXXXX"); + if (!temporary_mount) + return log_oom_debug(); + + if (!mkdtemp(temporary_mount)) + return log_debug_errno(errno, "Failed to create temporary directory '%s': %m", temporary_mount); + + *ret = TAKE_PTR(temporary_mount); + return 0; +} + +static int mount_private_dev(MountEntry *m, RuntimeScope scope) { + static const char devnodes[] = + "/dev/null\0" + "/dev/zero\0" + "/dev/full\0" + "/dev/random\0" + "/dev/urandom\0" + "/dev/tty\0"; + + _cleanup_free_ char *temporary_mount = NULL; + const char *dev = NULL, *devpts = NULL, *devshm = NULL, *devhugepages = NULL, *devmqueue = NULL, *devlog = NULL, *devptmx = NULL; + bool can_mknod = true; + int r; + + assert(m); + + r = create_temporary_mount_point(scope, &temporary_mount); + if (r < 0) + return r; + + dev = strjoina(temporary_mount, "/dev"); + (void) mkdir(dev, 0755); + r = mount_nofollow_verbose(LOG_DEBUG, "tmpfs", dev, "tmpfs", DEV_MOUNT_OPTIONS, "mode=0755" TMPFS_LIMITS_PRIVATE_DEV); + if (r < 0) + goto fail; + + r = label_fix_full(AT_FDCWD, dev, "/dev", 0); + if (r < 0) { + log_debug_errno(r, "Failed to fix label of '%s' as /dev: %m", dev); + goto fail; + } + + devpts = strjoina(temporary_mount, "/dev/pts"); + (void) mkdir(devpts, 0755); + r = mount_nofollow_verbose(LOG_DEBUG, "/dev/pts", devpts, NULL, MS_BIND, NULL); + if (r < 0) + 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_nofollow_verbose(LOG_DEBUG, "/dev/shm", devshm, NULL, MS_BIND, NULL); + if (r < 0) + goto fail; + + devmqueue = strjoina(temporary_mount, "/dev/mqueue"); + (void) mkdir(devmqueue, 0755); + (void) mount_nofollow_verbose(LOG_DEBUG, "/dev/mqueue", devmqueue, NULL, MS_BIND, NULL); + + devhugepages = strjoina(temporary_mount, "/dev/hugepages"); + (void) mkdir(devhugepages, 0755); + (void) mount_nofollow_verbose(LOG_DEBUG, "/dev/hugepages", devhugepages, NULL, MS_BIND, NULL); + + 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 *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 set up 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)); + + r = mount_nofollow_verbose(LOG_DEBUG, dev, mount_entry_path(m), NULL, MS_MOVE, NULL); + if (r < 0) + goto fail; + + (void) rmdir(dev); + (void) rmdir(temporary_mount); + + return 1; + +fail: + if (devpts) + (void) umount_verbose(LOG_DEBUG, devpts, UMOUNT_NOFOLLOW); + + if (devshm) + (void) umount_verbose(LOG_DEBUG, devshm, UMOUNT_NOFOLLOW); + + if (devhugepages) + (void) umount_verbose(LOG_DEBUG, devhugepages, UMOUNT_NOFOLLOW); + + if (devmqueue) + (void) umount_verbose(LOG_DEBUG, devmqueue, UMOUNT_NOFOLLOW); + + (void) umount_verbose(LOG_DEBUG, dev, UMOUNT_NOFOLLOW); + (void) rmdir(dev); + (void) 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; + + r = mount_nofollow_verbose(LOG_DEBUG, "/dev", mount_entry_path(m), NULL, MS_BIND|MS_REC, NULL); + if (r < 0) + return r; + + return 1; +} + +static int mount_bind_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. */ + r = mount_nofollow_verbose(LOG_DEBUG, "/sys", mount_entry_path(m), NULL, MS_BIND|MS_REC, NULL); + if (r < 0) + return r; + + return 1; +} + +static int mount_private_apivfs( + const char *fstype, + const char *entry_path, + const char *bind_source, + const char *opts, + RuntimeScope scope) { + + _cleanup_(rmdir_and_freep) char *temporary_mount = NULL; + int r; + + assert(fstype); + assert(entry_path); + assert(bind_source); + + (void) mkdir_p_label(entry_path, 0755); + + /* First, check if we have enough privileges to mount a new instance. Note, a new sysfs instance + * cannot be mounted on an already existing mount. Let's use a temporary place. */ + r = create_temporary_mount_point(scope, &temporary_mount); + if (r < 0) + return r; + + r = mount_nofollow_verbose(LOG_DEBUG, fstype, temporary_mount, fstype, MS_NOSUID|MS_NOEXEC|MS_NODEV, opts); + if (r == -EINVAL && opts) + /* If this failed with EINVAL then this likely means the textual hidepid= stuff for procfs is + * not supported by the kernel, and thus the per-instance hidepid= neither, which means we + * really don't want to use it, since it would affect our host's /proc mount. Hence let's + * gracefully fallback to a classic, unrestricted version. */ + r = mount_nofollow_verbose(LOG_DEBUG, fstype, temporary_mount, fstype, MS_NOSUID|MS_NOEXEC|MS_NODEV, /* opts = */ NULL); + if (ERRNO_IS_NEG_PRIVILEGE(r)) { + /* When we do not have enough privileges to mount a new instance, fall back to use an + * existing mount. */ + + r = path_is_mount_point(entry_path, /* root = */ NULL, /* flags = */ 0); + if (r < 0) + return log_debug_errno(r, "Unable to determine whether '%s' is already mounted: %m", entry_path); + if (r > 0) + return 0; /* Use the current mount as is. */ + + /* We lack permissions to mount a new instance, and it is not already mounted. But we can + * access the host's, so as a final fallback bind-mount it to the destination, as most likely + * we are inside a user manager in an unprivileged user namespace. */ + r = mount_nofollow_verbose(LOG_DEBUG, bind_source, entry_path, /* fstype = */ NULL, MS_BIND|MS_REC, /* opts = */ NULL); + if (r < 0) + return r; + + return 1; + + } else if (r < 0) + return r; + + /* OK. We have a new mount instance. Let's clear an existing mount and its submounts. */ + r = umount_recursive(entry_path, /* flags = */ 0); + if (r < 0) + log_debug_errno(r, "Failed to unmount directories below '%s', ignoring: %m", entry_path); + + /* Then, move the new mount instance. */ + r = mount_nofollow_verbose(LOG_DEBUG, temporary_mount, entry_path, /* fstype = */ NULL, MS_MOVE, /* opts = */ NULL); + if (r < 0) + return r; + + /* We mounted a new instance now. Let's bind mount the children over now. This matters for nspawn + * where a bunch of files are overmounted, in particular the boot id. */ + (void) bind_mount_submounts(bind_source, entry_path); + return 1; +} + +static int mount_private_sysfs(const MountEntry *m, const NamespaceParameters *p) { + assert(m); + assert(p); + return mount_private_apivfs("sysfs", mount_entry_path(m), "/sys", /* opts = */ NULL, p->runtime_scope); +} + +static int mount_procfs(const MountEntry *m, const NamespaceParameters *p) { + _cleanup_free_ char *opts = NULL; + + assert(m); + assert(p); + + if (p->protect_proc != PROTECT_PROC_DEFAULT || + p->proc_subset != PROC_SUBSET_ALL) { + + /* Starting with kernel 5.8 procfs' hidepid= logic is truly per-instance (previously it + * pretended to be per-instance but actually was per-namespace), hence let's make use of it + * if requested. To make sure this logic succeeds only on kernels where hidepid= is + * per-instance, we'll exclusively use the textual value for hidepid=, since support was + * added in the same commit: if it's supported it is thus also per-instance. */ + + const char *hpv = p->protect_proc == PROTECT_PROC_DEFAULT ? + "off" : + protect_proc_to_string(p->protect_proc); + + /* hidepid= support was added in 5.8, so we can use fsconfig()/fsopen() (which were added in + * 5.2) to check if hidepid= is supported. This avoids a noisy dmesg log by the kernel when + * trying to use hidepid= on systems where it isn't supported. The same applies for subset=. + * fsopen()/fsconfig() was also backported on some distros which allows us to detect + * hidepid=/subset= support in even more scenarios. */ + + if (mount_option_supported("proc", "hidepid", hpv) != 0) { + opts = strjoin("hidepid=", hpv); + if (!opts) + return -ENOMEM; + } + + if (p->proc_subset == PROC_SUBSET_PID && + mount_option_supported("proc", "subset", "pid") != 0) + if (!strextend_with_separator(&opts, ",", "subset=pid")) + return -ENOMEM; + } + + /* Mount a new instance, so that we get the one that matches our user namespace, if we are running in + * one. i.e we don't reuse existing mounts here under any condition, we want a new instance owned by + * our user namespace and with our hidepid= settings applied. Hence, let's get rid of everything + * mounted on /proc/ first. */ + return mount_private_apivfs("proc", mount_entry_path(m), "/proc", opts, p->runtime_scope); +} + +static int mount_tmpfs(const MountEntry *m) { + const char *entry_path, *inner_path; + int r; + + assert(m); + + entry_path = mount_entry_path(m); + inner_path = mount_entry_unprefixed_path(m); + + /* First, get rid of everything that is below if there is anything. Then, overmount with our new + * tmpfs */ + + (void) mkdir_p_label(entry_path, 0755); + (void) umount_recursive(entry_path, 0); + + r = mount_nofollow_verbose(LOG_DEBUG, "tmpfs", entry_path, "tmpfs", m->flags, mount_entry_options(m)); + if (r < 0) + return r; + + r = label_fix_full(AT_FDCWD, entry_path, inner_path, 0); + if (r < 0) + return log_debug_errno(r, "Failed to fix label of '%s' as '%s': %m", entry_path, inner_path); + + return 1; +} + +static int mount_run(const MountEntry *m) { + int r; + + assert(m); + + r = path_is_mount_point(mount_entry_path(m), NULL, 0); + if (r < 0 && r != -ENOENT) + return log_debug_errno(r, "Unable to determine whether /run is already mounted: %m"); + if (r > 0) /* make this a NOP if /run is already a mount point */ + return 0; + + return mount_tmpfs(m); +} + +static int mount_mqueuefs(const MountEntry *m) { + int r; + const char *entry_path; + + assert(m); + + entry_path = mount_entry_path(m); + + (void) mkdir_p_label(entry_path, 0755); + (void) umount_recursive(entry_path, 0); + + r = mount_nofollow_verbose(LOG_DEBUG, "mqueue", entry_path, "mqueue", m->flags, mount_entry_options(m)); + if (r < 0) + return r; + + return 1; +} + +static int mount_image( + const MountEntry *m, + const char *root_directory, + const ImagePolicy *image_policy) { + + _cleanup_free_ char *host_os_release_id = NULL, *host_os_release_version_id = NULL, + *host_os_release_sysext_level = NULL, *host_os_release_confext_level = NULL, + *extension_name = NULL; + int r; + + assert(m); + + r = path_extract_filename(mount_entry_source(m), &extension_name); + if (r < 0) + return log_debug_errno(r, "Failed to extract extension name from %s: %m", mount_entry_source(m)); + + if (m->mode == MOUNT_EXTENSION_IMAGE) { + r = parse_os_release( + empty_to_root(root_directory), + "ID", &host_os_release_id, + "VERSION_ID", &host_os_release_version_id, + image_class_info[IMAGE_SYSEXT].level_env, &host_os_release_sysext_level, + image_class_info[IMAGE_CONFEXT].level_env, &host_os_release_confext_level, + NULL); + if (r < 0) + return log_debug_errno(r, "Failed to acquire 'os-release' data of OS tree '%s': %m", empty_to_root(root_directory)); + if (isempty(host_os_release_id)) + return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "'ID' field not found or empty in 'os-release' data of OS tree '%s': %m", empty_to_root(root_directory)); + } + + r = verity_dissect_and_mount( + /* src_fd= */ -1, + mount_entry_source(m), + mount_entry_path(m), + m->image_options_const, + image_policy, + host_os_release_id, + host_os_release_version_id, + host_os_release_sysext_level, + host_os_release_confext_level, + /* required_sysext_scope= */ NULL, + /* ret_image= */ NULL); + if (r == -ENOENT && m->ignore) + return 0; + if (r == -ESTALE && host_os_release_id) + return log_error_errno(r, // FIXME: this should not be logged ad LOG_ERR, as it will result in duplicate logging. + "Failed to mount image %s, extension-release metadata does not match the lower layer's: ID=%s%s%s%s%s%s%s", + mount_entry_source(m), + host_os_release_id, + host_os_release_version_id ? " VERSION_ID=" : "", + strempty(host_os_release_version_id), + host_os_release_sysext_level ? image_class_info[IMAGE_SYSEXT].level_env_print : "", + strempty(host_os_release_sysext_level), + host_os_release_confext_level ? image_class_info[IMAGE_CONFEXT].level_env_print : "", + strempty(host_os_release_confext_level)); + if (r < 0) + return log_debug_errno(r, "Failed to mount image %s on %s: %m", mount_entry_source(m), mount_entry_path(m)); + + return 1; +} + +static int mount_overlay(const MountEntry *m) { + _cleanup_free_ char *options = NULL, *layers = NULL; + int r; + + assert(m); + + /* Extension hierarchies are optional (e.g.: confext might not have /opt) so check if they actually + * exist in an image before attempting to create an overlay with them, otherwise the mount will + * fail. We can't check before this, as the images will not be mounted until now. */ + + /* Note that lowerdir= parameters are in 'reverse' order, so the top-most directory in the overlay + * comes first in the list. */ + STRV_FOREACH_BACKWARDS(o, m->overlay_layers) { + _cleanup_free_ char *escaped = NULL; + + r = is_dir(*o, /* follow= */ false); + if (r <= 0) { + if (r != -ENOENT) + log_debug_errno(r, + "Failed to check whether overlay layer source path '%s' exists, ignoring: %m", + *o); + continue; + } + + escaped = shell_escape(*o, ",:"); + if (!escaped) + return log_oom_debug(); + + if (!strextend_with_separator(&layers, ":", escaped)) + return log_oom_debug(); + } + + if (!layers) { + log_debug("None of the overlays specified in '%s' exist at the source, skipping.", + mount_entry_options(m)); + return 0; /* Only the root is set? Then there's nothing to overlay */ + } + + options = strjoin("lowerdir=", layers, ":", mount_entry_path(m)); /* The root goes in last */ + if (!options) + return log_oom_debug(); + + (void) mkdir_p_label(mount_entry_path(m), 0755); + + r = mount_nofollow_verbose(LOG_DEBUG, "overlay", mount_entry_path(m), "overlay", MS_RDONLY, options); + if (r == -ENOENT && m->ignore) + return 0; + if (r < 0) + return r; + + 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(mount_entry_path(m), root_directory, CHASE_STEP|CHASE_NONEXISTENT, &target, NULL); + 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_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 %s.", + mount_entry_path(m), special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), target); + + mount_entry_consume_prefix(m, TAKE_PTR(target)); + + m->n_followed ++; + + return 0; +} + +static int apply_one_mount( + const char *root_directory, + MountEntry *m, + const NamespaceParameters *p) { + + _cleanup_free_ char *inaccessible = NULL; + bool rbind = true, make = false; + const char *what; + int r; + + /* Return 1 when the mount should be post-processed (remounted r/o, etc.), 0 otherwise. In most + * cases post-processing is the right thing, the typical exception is when the mount is gracefully + * skipped. */ + + assert(m); + assert(p); + + log_debug("Applying namespace mount on %s", mount_entry_path(m)); + + switch (m->mode) { + + case MOUNT_INACCESSIBLE: { + _cleanup_free_ char *runtime_dir = NULL; + 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)); + } + + /* We don't pass the literal runtime scope through here but one based purely on our UID. This + * means that the root user's --user services will use the host's inaccessible inodes rather + * then root's private ones. This is preferable since it means device nodes that are + * overmounted to make them inaccessible will be overmounted with a device node, rather than + * an AF_UNIX socket inode. */ + runtime_dir = settle_runtime_dir(geteuid() == 0 ? RUNTIME_SCOPE_SYSTEM : RUNTIME_SCOPE_USER); + if (!runtime_dir) + return log_oom_debug(); + + r = mode_to_inaccessible_node(runtime_dir, target.st_mode, &inaccessible); + if (r < 0) + return log_debug_errno(SYNTHETIC_ERRNO(ELOOP), + "File type not supported for inaccessible mounts. Note that symlinks are not allowed"); + what = inaccessible; + break; + } + + case MOUNT_READ_ONLY: + case MOUNT_READ_WRITE: + case MOUNT_READ_WRITE_IMPLICIT: + case MOUNT_EXEC: + case MOUNT_NOEXEC: + 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 + * and MS_NOEXEC bits for the mount point if needed. */ + return 1; + /* This isn't a mount point yet, let's make it one. */ + what = mount_entry_path(m); + break; + + case MOUNT_EXTENSION_DIRECTORY: { + _cleanup_free_ char *host_os_release_id = NULL, *host_os_release_version_id = NULL, + *host_os_release_level = NULL, *extension_name = NULL; + _cleanup_strv_free_ char **extension_release = NULL; + ImageClass class = IMAGE_SYSEXT; + + r = path_extract_filename(mount_entry_source(m), &extension_name); + if (r < 0) + return log_debug_errno(r, "Failed to extract extension name from %s: %m", mount_entry_source(m)); + + r = load_extension_release_pairs(mount_entry_source(m), IMAGE_SYSEXT, extension_name, /* relax_extension_release_check= */ false, &extension_release); + if (r == -ENOENT) { + r = load_extension_release_pairs(mount_entry_source(m), IMAGE_CONFEXT, extension_name, /* relax_extension_release_check= */ false, &extension_release); + if (r >= 0) + class = IMAGE_CONFEXT; + } + if (r < 0) + return log_debug_errno(r, "Failed to acquire 'extension-release' data of extension tree %s: %m", mount_entry_source(m)); + + r = parse_os_release( + empty_to_root(root_directory), + "ID", &host_os_release_id, + "VERSION_ID", &host_os_release_version_id, + image_class_info[class].level_env, &host_os_release_level, + NULL); + if (r < 0) + return log_debug_errno(r, "Failed to acquire 'os-release' data of OS tree '%s': %m", empty_to_root(root_directory)); + if (isempty(host_os_release_id)) + return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "'ID' field not found or empty in 'os-release' data of OS tree '%s': %m", empty_to_root(root_directory)); + + r = load_extension_release_pairs(mount_entry_source(m), class, extension_name, /* relax_extension_release_check= */ false, &extension_release); + if (r == -ENOENT && m->ignore) + return 0; + if (r < 0) + return log_debug_errno(r, "Failed to parse directory %s extension-release metadata: %m", extension_name); + + r = extension_release_validate( + extension_name, + host_os_release_id, + host_os_release_version_id, + host_os_release_level, + /* host_extension_scope */ NULL, /* Leave empty, we need to accept both system and portable */ + extension_release, + class); + if (r == 0) + return log_debug_errno(SYNTHETIC_ERRNO(ESTALE), "Directory %s extension-release metadata does not match the root's", extension_name); + if (r < 0) + return log_debug_errno(r, "Failed to compare directory %s extension-release metadata with the root's os-release: %m", extension_name); + + _fallthrough_; + } + + case MOUNT_BIND: + rbind = false; + + _fallthrough_; + case MOUNT_BIND_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() here. */ + + r = chase(mount_entry_source(m), NULL, CHASE_TRAIL_SLASH, &chased, NULL); + 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 %s.", + mount_entry_source(m), special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), chased); + + free_and_replace(m->source_malloc, chased); + + what = mount_entry_source(m); + make = true; + break; + } + + case MOUNT_EMPTY_DIR: + case MOUNT_TMPFS: + return mount_tmpfs(m); + + case MOUNT_PRIVATE_TMP: + case MOUNT_PRIVATE_TMP_READ_ONLY: + what = mount_entry_source(m); + make = true; + break; + + case MOUNT_PRIVATE_DEV: + return mount_private_dev(m, p->runtime_scope); + + case MOUNT_BIND_DEV: + return mount_bind_dev(m); + + case MOUNT_PRIVATE_SYSFS: + return mount_private_sysfs(m, p); + + case MOUNT_BIND_SYSFS: + return mount_bind_sysfs(m); + + case MOUNT_PROCFS: + return mount_procfs(m, p); + + case MOUNT_RUN: + return mount_run(m); + + case MOUNT_MQUEUEFS: + return mount_mqueuefs(m); + + case MOUNT_IMAGE: + return mount_image(m, NULL, p->mount_image_policy); + + case MOUNT_EXTENSION_IMAGE: + return mount_image(m, root_directory, p->extension_image_policy); + + case MOUNT_OVERLAY: + return mount_overlay(m); + + default: + assert_not_reached(); + } + + assert(what); + + r = mount_nofollow_verbose(LOG_DEBUG, what, mount_entry_path(m), NULL, MS_BIND|(rbind ? MS_REC : 0), NULL); + if (r < 0) { + bool try_again = false; + + if (r == -ENOENT && make) { + int q; + + /* Hmm, either the source or the destination are missing. Let's see if we can create + the destination, then try again. */ + + (void) mkdir_parents(mount_entry_path(m), 0755); + + q = make_mount_point_inode_from_path(what, mount_entry_path(m), 0755); + if (q < 0) { + if (q != -EEXIST) // FIXME: this shouldn't be logged at LOG_WARNING, but be bubbled up, and logged there to avoid duplicate logging + log_warning_errno(q, "Failed to create destination mount point node '%s', ignoring: %m", + mount_entry_path(m)); + } else + try_again = true; + } + + if (try_again) + r = mount_nofollow_verbose(LOG_DEBUG, what, mount_entry_path(m), NULL, MS_BIND|(rbind ? MS_REC : 0), NULL); + if (r < 0) + return log_error_errno(r, "Failed to mount %s to %s: %m", what, mount_entry_path(m)); // FIXME: this should not be logged here, but be bubbled up, to avoid duplicate logging + } + + log_debug("Successfully mounted %s to %s", what, mount_entry_path(m)); + return 1; +} + +static int make_read_only(const MountEntry *m, char **deny_list, FILE *proc_self_mountinfo) { + unsigned long new_flags = 0, flags_mask = 0; + bool submounts; + int r; + + assert(m); + assert(proc_self_mountinfo); + + if (m->state != MOUNT_APPLIED) + return 0; + + if (mount_entry_read_only(m) || m->mode == MOUNT_PRIVATE_DEV) { + new_flags |= MS_RDONLY; + flags_mask |= MS_RDONLY; + } + + if (m->nosuid) { + new_flags |= MS_NOSUID; + flags_mask |= MS_NOSUID; + } + + if (flags_mask == 0) /* No Change? */ + return 0; + + /* We generally apply these changes recursively, except for /dev, and the cases we know there's + * nothing further down. 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. */ + submounts = + mount_entry_read_only(m) && + !IN_SET(m->mode, MOUNT_EMPTY_DIR, MOUNT_TMPFS); + if (submounts) + r = bind_remount_recursive_with_mountinfo(mount_entry_path(m), new_flags, flags_mask, deny_list, proc_self_mountinfo); + else + r = bind_remount_one_with_mountinfo(mount_entry_path(m), new_flags, flags_mask, proc_self_mountinfo); + + /* Note 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) + return 0; + if (r < 0) + return log_debug_errno(r, "Failed to re-mount '%s'%s: %m", mount_entry_path(m), + submounts ? " and its submounts" : ""); + return 0; +} + +static int make_noexec(const MountEntry *m, char **deny_list, FILE *proc_self_mountinfo) { + unsigned long new_flags = 0, flags_mask = 0; + bool submounts; + int r; + + assert(m); + assert(proc_self_mountinfo); + + if (m->state != MOUNT_APPLIED) + return 0; + + if (mount_entry_noexec(m)) { + new_flags |= MS_NOEXEC; + flags_mask |= MS_NOEXEC; + } else if (mount_entry_exec(m)) { + new_flags &= ~MS_NOEXEC; + flags_mask |= MS_NOEXEC; + } + + if (flags_mask == 0) /* No Change? */ + return 0; + + submounts = !IN_SET(m->mode, MOUNT_EMPTY_DIR, MOUNT_TMPFS); + + if (submounts) + r = bind_remount_recursive_with_mountinfo(mount_entry_path(m), new_flags, flags_mask, deny_list, proc_self_mountinfo); + else + r = bind_remount_one_with_mountinfo(mount_entry_path(m), new_flags, flags_mask, proc_self_mountinfo); + + if (r == -ENOENT && m->ignore) + return 0; + if (r < 0) + return log_debug_errno(r, "Failed to re-mount '%s'%s: %m", mount_entry_path(m), + submounts ? " and its submounts" : ""); + return 0; +} + +static int make_nosuid(const MountEntry *m, FILE *proc_self_mountinfo) { + bool submounts; + int r; + + assert(m); + assert(proc_self_mountinfo); + + if (m->state != MOUNT_APPLIED) + return 0; + + submounts = !IN_SET(m->mode, MOUNT_EMPTY_DIR, MOUNT_TMPFS); + if (submounts) + r = bind_remount_recursive_with_mountinfo(mount_entry_path(m), MS_NOSUID, MS_NOSUID, NULL, proc_self_mountinfo); + else + r = bind_remount_one_with_mountinfo(mount_entry_path(m), MS_NOSUID, MS_NOSUID, proc_self_mountinfo); + if (r == -ENOENT && m->ignore) + return 0; + if (r < 0) + return log_debug_errno(r, "Failed to re-mount '%s'%s: %m", mount_entry_path(m), + submounts ? " and its submounts" : ""); + return 0; +} + +static bool namespace_parameters_mount_apivfs(const NamespaceParameters *p) { + assert(p); + + /* + * ProtectControlGroups= and ProtectKernelTunables= imply MountAPIVFS=, + * since to protect the API VFS mounts, they need to be around in the + * first place... + */ + + return p->mount_apivfs || + p->protect_control_groups || + p->protect_kernel_tunables || + p->protect_proc != PROTECT_PROC_DEFAULT || + p->proc_subset != PROC_SUBSET_ALL; +} + +/* Walk all mount entries and dropping any unused mounts. This affects all + * mounts: + * - that are implicitly protected by a path that has been rendered inaccessible + * - whose immediate parent requests the same protection mode as the mount itself + * - that are outside of the relevant root directory + * - which are duplicates + */ +static void drop_unused_mounts(MountList *ml, const char *root_directory) { + assert(ml); + assert(root_directory); + + assert(ml->mounts || ml->n_mounts == 0); + + typesafe_qsort(ml->mounts, ml->n_mounts, mount_path_compare); + + drop_duplicates(ml); + drop_outside_root(ml, root_directory); + drop_inaccessible(ml); + drop_nop(ml); +} + +static int create_symlinks_from_tuples(const char *root, char **strv_symlinks) { + int r; + + STRV_FOREACH_PAIR(src, dst, strv_symlinks) { + _cleanup_free_ char *src_abs = NULL, *dst_abs = NULL; + + src_abs = path_join(root, *src); + dst_abs = path_join(root, *dst); + if (!src_abs || !dst_abs) + return -ENOMEM; + + r = mkdir_parents_label(dst_abs, 0755); + if (r < 0) + return log_debug_errno( + r, + "Failed to create parent directory for symlink '%s': %m", + dst_abs); + + r = symlink_idempotent(src_abs, dst_abs, true); + if (r < 0) + return log_debug_errno( + r, + "Failed to create symlink from '%s' to '%s': %m", + src_abs, + dst_abs); + } + + return 0; +} + +static void mount_entry_path_debug_string(const char *root, MountEntry *m, char **error_path) { + assert(m); + + /* Create a string suitable for debugging logs, stripping for example the local working directory. + * For example, with a BindPaths=/var/bar that does not exist on the host: + * + * Before: + * foo.service: Failed to set up mount namespacing: /run/systemd/unit-root/var/bar: No such file or directory + * After: + * foo.service: Failed to set up mount namespacing: /var/bar: No such file or directory + * + * Note that this is an error path, so no OOM check is done on purpose. */ + + if (!error_path) + return; + + if (!mount_entry_path(m)) { + *error_path = NULL; + return; + } + + if (root) { + const char *e = startswith(mount_entry_path(m), root); + if (e) { + *error_path = strdup(e); + return; + } + } + + *error_path = strdup(mount_entry_path(m)); + return; +} + +static int apply_mounts( + MountList *ml, + const char *root, + const NamespaceParameters *p, + char **error_path) { + + _cleanup_fclose_ FILE *proc_self_mountinfo = NULL; + _cleanup_free_ char **deny_list = NULL; + int r; + + assert(ml); + assert(root); + assert(p); + + if (ml->n_mounts == 0) /* Shortcut: nothing to do */ + return 0; + + /* 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 = -errno; + + if (error_path) + *error_path = strdup("/proc/self/mountinfo"); + + return log_debug_errno(r, "Failed to open /proc/self/mountinfo: %m"); + } + + /* First round, establish all mounts we need */ + for (;;) { + bool again = false; + + FOREACH_ARRAY(m, ml->mounts, ml->n_mounts) { + + if (m->state != MOUNT_PENDING) + continue; + + /* ExtensionImages/Directories are first opened in the propagate directory, not in the root_directory */ + r = follow_symlink(!IN_SET(m->mode, MOUNT_EXTENSION_IMAGE, MOUNT_EXTENSION_DIRECTORY) ? root : NULL, m); + if (r < 0) { + mount_entry_path_debug_string(root, m, error_path); + return r; + } + 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; + } + + /* Returns 1 if the mount should be post-processed, 0 otherwise */ + r = apply_one_mount(root, m, p); + if (r < 0) { + mount_entry_path_debug_string(root, m, error_path); + return r; + } + m->state = r == 0 ? MOUNT_SKIPPED : MOUNT_APPLIED; + } + + if (!again) + break; + + drop_unused_mounts(ml, root); + } + + /* Now that all filesystems have been set up, but before the + * read-only switches are flipped, create the exec dirs and other symlinks. + * Note that when /var/lib is not empty/tmpfs, these symlinks will already + * exist, which means this will be a no-op. */ + r = create_symlinks_from_tuples(root, p->symlinks); + if (r < 0) + return log_debug_errno(r, "Failed to set up symlinks inside mount namespace: %m"); + + /* Create a deny list we can pass to bind_mount_recursive() */ + deny_list = new(char*, ml->n_mounts+1); + if (!deny_list) + return -ENOMEM; + for (size_t j = 0; j < ml->n_mounts; j++) + deny_list[j] = (char*) mount_entry_path(ml->mounts+j); + deny_list[ml->n_mounts] = NULL; + + /* Second round, flip the ro bits if necessary. */ + FOREACH_ARRAY(m, ml->mounts, ml->n_mounts) { + r = make_read_only(m, deny_list, proc_self_mountinfo); + if (r < 0) { + mount_entry_path_debug_string(root, m, error_path); + return r; + } + } + + /* Third round, flip the noexec bits with a simplified deny list. */ + for (size_t j = 0; j < ml->n_mounts; j++) + if (IN_SET((ml->mounts+j)->mode, MOUNT_EXEC, MOUNT_NOEXEC)) + deny_list[j] = (char*) mount_entry_path(ml->mounts+j); + deny_list[ml->n_mounts] = NULL; + + FOREACH_ARRAY(m, ml->mounts, ml->n_mounts) { + r = make_noexec(m, deny_list, proc_self_mountinfo); + if (r < 0) { + mount_entry_path_debug_string(root, m, error_path); + return r; + } + } + + /* Fourth round, flip the nosuid bits without a deny list. */ + if (p->mount_nosuid) + FOREACH_ARRAY(m, ml->mounts, ml->n_mounts) { + r = make_nosuid(m, proc_self_mountinfo); + if (r < 0) { + mount_entry_path_debug_string(root, m, error_path); + return r; + } + } + + return 1; +} + +static bool root_read_only( + char **read_only_paths, + ProtectSystem protect_system) { + + /* Determine whether the root directory is going to be read-only given the configured settings. */ + + if (protect_system == PROTECT_SYSTEM_STRICT) + return true; + + if (prefixed_path_strv_contains(read_only_paths, "/")) + return true; + + return false; +} + +static bool home_read_only( + 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, + ProtectHome protect_home) { + + /* Determine whether the /home directory is going to be read-only given the configured settings. Yes, + * this is a bit sloppy, since we don't bother checking for cases where / is affected by multiple + * settings. */ + + if (protect_home != PROTECT_HOME_NO) + return true; + + if (prefixed_path_strv_contains(read_only_paths, "/home") || + prefixed_path_strv_contains(inaccessible_paths, "/home") || + prefixed_path_strv_contains(empty_directories, "/home")) + return true; + + for (size_t i = 0; i < n_temporary_filesystems; i++) + if (path_equal(temporary_filesystems[i].path, "/home")) + return true; + + /* If /home is overmounted with some dir from the host it's not writable. */ + for (size_t i = 0; i < n_bind_mounts; i++) + if (path_equal(bind_mounts[i].destination, "/home")) + return true; + + return false; +} + +int setup_namespace(const NamespaceParameters *p, char **error_path) { + + _cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL; + _cleanup_(dissected_image_unrefp) DissectedImage *dissected_image = NULL; + _cleanup_strv_free_ char **hierarchies = NULL; + _cleanup_(mount_list_done) MountList ml = {}; + bool require_prefix = false; + const char *root; + DissectImageFlags dissect_image_flags = + DISSECT_IMAGE_GENERIC_ROOT | + DISSECT_IMAGE_REQUIRE_ROOT | + DISSECT_IMAGE_DISCARD_ON_LOOP | + DISSECT_IMAGE_RELAX_VAR_CHECK | + DISSECT_IMAGE_FSCK | + DISSECT_IMAGE_USR_NO_ROOT | + DISSECT_IMAGE_GROWFS | + DISSECT_IMAGE_ADD_PARTITION_DEVICES | + DISSECT_IMAGE_PIN_PARTITION_DEVICES; + int r; + + assert(p); + + /* Make sure that all mknod(), mkdir() calls we do are unaffected by the umask, and the access modes + * we configure take effect */ + BLOCK_WITH_UMASK(0000); + + bool setup_propagate = !isempty(p->propagate_dir) && !isempty(p->incoming_dir); + unsigned long mount_propagation_flag = p->mount_propagation_flag != 0 ? p->mount_propagation_flag : MS_SHARED; + + if (p->root_image) { + /* Make the whole image read-only if we can determine that we only access it in a read-only fashion. */ + if (root_read_only(p->read_only_paths, + p->protect_system) && + home_read_only(p->read_only_paths, p->inaccessible_paths, p->empty_directories, + p->bind_mounts, p->n_bind_mounts, p->temporary_filesystems, p->n_temporary_filesystems, + p->protect_home) && + strv_isempty(p->read_write_paths)) + dissect_image_flags |= DISSECT_IMAGE_READ_ONLY; + + SET_FLAG(dissect_image_flags, DISSECT_IMAGE_NO_PARTITION_TABLE, p->verity && p->verity->data_path); + + r = loop_device_make_by_path( + p->root_image, + FLAGS_SET(dissect_image_flags, DISSECT_IMAGE_DEVICE_READ_ONLY) ? O_RDONLY : -1 /* < 0 means writable if possible, read-only as fallback */, + /* sector_size= */ UINT32_MAX, + FLAGS_SET(dissect_image_flags, DISSECT_IMAGE_NO_PARTITION_TABLE) ? 0 : LO_FLAGS_PARTSCAN, + LOCK_SH, + &loop_device); + if (r < 0) + return log_debug_errno(r, "Failed to create loop device for root image: %m"); + + r = dissect_loop_device( + loop_device, + p->verity, + p->root_image_options, + p->root_image_policy, + dissect_image_flags, + &dissected_image); + if (r < 0) + return log_debug_errno(r, "Failed to dissect image: %m"); + + r = dissected_image_load_verity_sig_partition( + dissected_image, + loop_device->fd, + p->verity); + if (r < 0) + return r; + + r = dissected_image_decrypt( + dissected_image, + NULL, + p->verity, + dissect_image_flags); + if (r < 0) + return log_debug_errno(r, "Failed to decrypt dissected image: %m"); + } + + if (p->root_directory) + root = p->root_directory; + else { + /* /run/systemd should have been created by PID 1 early on already, but in some cases, like + * when running tests (test-execute), it might not have been created yet so let's make sure + * we create it if it doesn't already exist. */ + (void) mkdir_p_label("/run/systemd", 0755); + + /* 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. (Note: this directory is also created by PID 1 early on, we create it here for + * similar reasons as /run/systemd/ first.) */ + root = "/run/systemd/mount-rootfs"; + (void) mkdir_label(root, 0555); + + require_prefix = true; + } + + if (p->n_extension_images > 0 || !strv_isempty(p->extension_directories)) { + /* Hierarchy population needs to be done for sysext and confext extension images */ + r = parse_env_extension_hierarchies(&hierarchies, "SYSTEMD_SYSEXT_AND_CONFEXT_HIERARCHIES"); + if (r < 0) + return r; + } + + r = append_access_mounts(&ml, p->read_write_paths, MOUNT_READ_WRITE, require_prefix); + if (r < 0) + return r; + + r = append_access_mounts(&ml, p->read_only_paths, MOUNT_READ_ONLY, require_prefix); + if (r < 0) + return r; + + r = append_access_mounts(&ml, p->inaccessible_paths, MOUNT_INACCESSIBLE, require_prefix); + if (r < 0) + return r; + + r = append_access_mounts(&ml, p->exec_paths, MOUNT_EXEC, require_prefix); + if (r < 0) + return r; + + r = append_access_mounts(&ml, p->no_exec_paths, MOUNT_NOEXEC, require_prefix); + if (r < 0) + return r; + + r = append_empty_dir_mounts(&ml, p->empty_directories); + if (r < 0) + return r; + + r = append_bind_mounts(&ml, p->bind_mounts, p->n_bind_mounts); + if (r < 0) + return r; + + r = append_tmpfs_mounts(&ml, p->temporary_filesystems, p->n_temporary_filesystems); + if (r < 0) + return r; + + if (p->tmp_dir) { + bool ro = streq(p->tmp_dir, RUN_SYSTEMD_EMPTY); + + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/tmp", + .mode = ro ? MOUNT_PRIVATE_TMP_READ_ONLY : MOUNT_PRIVATE_TMP, + .source_const = p->tmp_dir, + }; + } + + if (p->var_tmp_dir) { + bool ro = streq(p->var_tmp_dir, RUN_SYSTEMD_EMPTY); + + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/var/tmp", + .mode = ro ? MOUNT_PRIVATE_TMP_READ_ONLY : MOUNT_PRIVATE_TMP, + .source_const = p->var_tmp_dir, + }; + } + + r = append_mount_images(&ml, p->mount_images, p->n_mount_images); + if (r < 0) + return r; + + r = append_extensions(&ml, root, p->extension_dir, hierarchies, p->extension_images, p->n_extension_images, p->extension_directories); + if (r < 0) + return r; + + if (p->private_dev) { + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/dev", + .mode = MOUNT_PRIVATE_DEV, + .flags = DEV_MOUNT_OPTIONS, + }; + } + + /* In case /proc is successfully mounted with pid tree subset only (ProcSubset=pid), the protective + mounts to non-pid /proc paths would fail. But the pid only option may have failed gracefully, so + let's try the mounts but it's not fatal if they don't succeed. */ + bool ignore_protect_proc = p->ignore_protect_paths || p->proc_subset == PROC_SUBSET_PID; + if (p->protect_kernel_tunables) { + r = append_static_mounts(&ml, + protect_kernel_tunables_proc_table, + ELEMENTSOF(protect_kernel_tunables_proc_table), + ignore_protect_proc); + if (r < 0) + return r; + + r = append_static_mounts(&ml, + protect_kernel_tunables_sys_table, + ELEMENTSOF(protect_kernel_tunables_sys_table), + p->ignore_protect_paths); + if (r < 0) + return r; + } + + if (p->protect_kernel_modules) { + r = append_static_mounts(&ml, + protect_kernel_modules_table, + ELEMENTSOF(protect_kernel_modules_table), + p->ignore_protect_paths); + if (r < 0) + return r; + } + + if (p->protect_kernel_logs) { + r = append_static_mounts(&ml, + protect_kernel_logs_proc_table, + ELEMENTSOF(protect_kernel_logs_proc_table), + ignore_protect_proc); + if (r < 0) + return r; + + r = append_static_mounts(&ml, + protect_kernel_logs_dev_table, + ELEMENTSOF(protect_kernel_logs_dev_table), + p->ignore_protect_paths); + if (r < 0) + return r; + } + + if (p->protect_control_groups) { + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/sys/fs/cgroup", + .mode = MOUNT_READ_ONLY, + }; + } + + r = append_protect_home(&ml, p->protect_home, p->ignore_protect_paths); + if (r < 0) + return r; + + r = append_protect_system(&ml, p->protect_system, false); + if (r < 0) + return r; + + if (namespace_parameters_mount_apivfs(p)) { + r = append_static_mounts(&ml, + apivfs_table, + ELEMENTSOF(apivfs_table), + p->ignore_protect_paths); + if (r < 0) + return r; + } + + /* Note, if proc is mounted with subset=pid then neither of the two paths will exist, i.e. they are + * implicitly protected by the mount option. */ + if (p->protect_hostname) { + r = append_static_mounts( + &ml, + protect_hostname_table, + ELEMENTSOF(protect_hostname_table), + ignore_protect_proc); + if (r < 0) + return r; + } + + if (p->private_network) { + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/sys", + .mode = MOUNT_PRIVATE_SYSFS, + }; + } + + if (p->private_ipc) { + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/dev/mqueue", + .mode = MOUNT_MQUEUEFS, + .flags = MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_RELATIME, + }; + } + + if (p->creds_path) { + /* If our service has a credentials store configured, then bind that one in, but hide + * everything else. */ + + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/run/credentials", + .mode = MOUNT_TMPFS, + .read_only = true, + .options_const = "mode=0755" TMPFS_LIMITS_EMPTY_OR_ALMOST, + .flags = MS_NODEV|MS_STRICTATIME|MS_NOSUID|MS_NOEXEC, + }; + + me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = p->creds_path, + .mode = MOUNT_BIND, + .read_only = true, + .source_const = p->creds_path, + .ignore = true, + }; + } else { + /* If our service has no credentials store configured, then make the whole credentials tree + * inaccessible wholesale. */ + + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/run/credentials", + .mode = MOUNT_INACCESSIBLE, + .ignore = true, + }; + } + + if (p->log_namespace) { + _cleanup_free_ char *q = NULL; + + q = strjoin("/run/systemd/journal.", p->log_namespace); + if (!q) + return log_oom_debug(); + + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/run/systemd/journal", + .mode = MOUNT_BIND_RECURSIVE, + .read_only = true, + .source_malloc = TAKE_PTR(q), + }; + } + + /* Will be used to add bind mounts at runtime */ + if (setup_propagate) { + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .source_const = p->propagate_dir, + .path_const = p->incoming_dir, + .mode = MOUNT_BIND, + .read_only = true, + }; + } + + if (p->notify_socket) { + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = p->notify_socket, + .source_const = p->notify_socket, + .mode = MOUNT_BIND, + .read_only = true, + }; + } + + if (p->host_os_release_stage) { + MountEntry *me = mount_list_extend(&ml); + if (!me) + return log_oom_debug(); + + *me = (MountEntry) { + .path_const = "/run/host/.os-release-stage/", + .source_const = p->host_os_release_stage, + .mode = MOUNT_BIND, + .read_only = true, + .ignore = true, /* Live copy, don't hard-fail if it goes missing */ + }; + } + + /* Prepend the root directory where that's necessary */ + r = prefix_where_needed(&ml, root); + if (r < 0) + return r; + + drop_unused_mounts(&ml, root); + + /* 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 (ERRNO_IS_PRIVILEGE(r) || + ERRNO_IS_NOT_SUPPORTED(r)) + /* 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. */ + return -ENOANO; + + return r; + } + + /* Create the source directory to allow runtime propagation of mounts */ + if (setup_propagate) + (void) mkdir_p(p->propagate_dir, 0600); + + if (p->n_extension_images > 0 || !strv_isempty(p->extension_directories)) + /* ExtensionImages/Directories mountpoint directories will be created while parsing the + * mounts to create, so have the parent ready */ + (void) mkdir_p(p->extension_dir, 0600); + + /* Remount / as SLAVE so that nothing now mounted in the namespace + * shows up in the parent */ + if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) + return log_debug_errno(errno, "Failed to remount '/' as SLAVE: %m"); + + if (p->root_image) { + /* A root image is specified, mount it to the right place */ + r = dissected_image_mount( + dissected_image, + root, + /* uid_shift= */ UID_INVALID, + /* uid_range= */ UID_INVALID, + /* userns_fd= */ -EBADF, + dissect_image_flags); + if (r < 0) + return log_debug_errno(r, "Failed to mount root image: %m"); + + /* Now release the block device lock, so that udevd is free to call BLKRRPART on the device + * if it likes. */ + r = loop_device_flock(loop_device, LOCK_UN); + if (r < 0) + return log_debug_errno(r, "Failed to release lock on loopback block device: %m"); + + r = dissected_image_relinquish(dissected_image); + if (r < 0) + return log_debug_errno(r, "Failed to relinquish dissected image: %m"); + + } else if (p->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) + return log_debug_errno(r, "Failed to detect that %s is a mount point or not: %m", root); + if (r == 0) { + r = mount_nofollow_verbose(LOG_DEBUG, root, root, NULL, MS_BIND|MS_REC, NULL); + if (r < 0) + return r; + } + + } else { + /* Let's mount the main root directory to the root directory to use */ + r = mount_nofollow_verbose(LOG_DEBUG, "/", root, NULL, MS_BIND|MS_REC, NULL); + if (r < 0) + return r; + } + + /* Try to set up the new root directory before mounting anything else there. */ + if (p->root_image || p->root_directory) + (void) base_filesystem_create(root, UID_INVALID, GID_INVALID); + + /* Now make the magic happen */ + r = apply_mounts(&ml, root, p, error_path); + if (r < 0) + return r; + + /* MS_MOVE does not work on MS_SHARED so the remount MS_SHARED will be done later */ + r = mount_switch_root(root, /* mount_propagation_flag = */ 0); + if (r == -EINVAL && p->root_directory) { + /* If we are using root_directory and we don't have privileges (ie: user manager in a user + * namespace) and the root_directory is already a mount point in the parent namespace, + * MS_MOVE will fail as we don't have permission to change it (with EINVAL rather than + * EPERM). Attempt to bind-mount it over itself (like we do above if it's not already a + * mount point) and try again. */ + r = mount_nofollow_verbose(LOG_DEBUG, root, root, NULL, MS_BIND|MS_REC, NULL); + if (r < 0) + return r; + r = mount_switch_root(root, /* mount_propagation_flag = */ 0); + } + if (r < 0) + return log_debug_errno(r, "Failed to mount root with MS_MOVE: %m"); + + /* 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_propagation_flag | MS_REC, NULL) < 0) + return log_debug_errno(errno, "Failed to remount '/' with desired mount flags: %m"); + + /* bind_mount_in_namespace() will MS_MOVE into that directory, and that's only supported for + * non-shared mounts. This needs to happen after remounting / or it will fail. */ + if (setup_propagate && mount(NULL, p->incoming_dir, NULL, MS_SLAVE, NULL) < 0) + return log_debug_errno(errno, "Failed to remount %s with MS_SLAVE: %m", p->incoming_dir); + + return 0; +} + +void bind_mount_free_many(BindMount *b, size_t n) { + assert(b || n == 0); + + for (size_t 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, + .nosuid = item->nosuid, + .recursive = item->recursive, + .ignore_enoent = item->ignore_enoent, + }; + + return 0; +} + +MountImage* mount_image_free_many(MountImage *m, size_t *n) { + assert(n); + assert(m || *n == 0); + + for (size_t i = 0; i < *n; i++) { + free(m[i].source); + free(m[i].destination); + mount_options_free_all(m[i].mount_options); + } + + free(m); + *n = 0; + return NULL; +} + +int mount_image_add(MountImage **m, size_t *n, const MountImage *item) { + _cleanup_free_ char *s = NULL, *d = NULL; + _cleanup_(mount_options_free_allp) MountOptions *options = NULL; + MountImage *c; + + assert(m); + assert(n); + assert(item); + + s = strdup(item->source); + if (!s) + return -ENOMEM; + + if (item->destination) { + d = strdup(item->destination); + if (!d) + return -ENOMEM; + } + + LIST_FOREACH(mount_options, i, item->mount_options) { + _cleanup_(mount_options_free_allp) MountOptions *o = NULL; + + o = new(MountOptions, 1); + if (!o) + return -ENOMEM; + + *o = (MountOptions) { + .partition_designator = i->partition_designator, + .options = strdup(i->options), + }; + if (!o->options) + return -ENOMEM; + + LIST_APPEND(mount_options, options, TAKE_PTR(o)); + } + + c = reallocarray(*m, *n + 1, sizeof(MountImage)); + if (!c) + return -ENOMEM; + + *m = c; + + c[(*n) ++] = (MountImage) { + .source = TAKE_PTR(s), + .destination = TAKE_PTR(d), + .mount_options = TAKE_PTR(options), + .ignore_enoent = item->ignore_enoent, + .type = item->type, + }; + + return 0; +} + +void temporary_filesystem_free_many(TemporaryFileSystem *t, size_t n) { + assert(t || n == 0); + + for (size_t 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 make_tmp_prefix(const char *prefix) { + _cleanup_free_ char *t = NULL; + _cleanup_close_ int fd = -EBADF; + int r; + + /* Don't do anything unless we know the dir is actually missing */ + r = access(prefix, F_OK); + if (r >= 0) + return 0; + if (errno != ENOENT) + return -errno; + + WITH_UMASK(000) + r = mkdir_parents(prefix, 0755); + if (r < 0) + return r; + + r = tempfn_random(prefix, NULL, &t); + if (r < 0) + return r; + + /* umask will corrupt this access mode, but that doesn't matter, we need to call chmod() anyway for + * the suid bit, below. */ + fd = open_mkdir_at(AT_FDCWD, t, O_EXCL|O_CLOEXEC, 0777); + if (fd < 0) + return fd; + + r = RET_NERRNO(fchmod(fd, 01777)); + if (r < 0) { + (void) rmdir(t); + return r; + } + + r = RET_NERRNO(rename(t, prefix)); + if (r < 0) { + (void) rmdir(t); + return r == -EEXIST ? 0 : r; /* it's fine if someone else created the dir by now */ + } + + return 0; + +} + +static int setup_one_tmp_dir(const char *id, const char *prefix, char **path, char **tmp_path) { + _cleanup_free_ char *x = NULL; + _cleanup_free_ char *y = NULL; + sd_id128_t boot_id; + bool rw = true; + 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), "-", id, "-XXXXXX"); + if (!x) + return -ENOMEM; + + r = make_tmp_prefix(prefix); + if (r < 0) + return r; + + WITH_UMASK(0077) + if (!mkdtemp(x)) { + if (errno == EROFS || ERRNO_IS_DISK_SPACE(errno)) + rw = false; + else + return -errno; + } + + if (rw) { + y = strjoin(x, "/tmp"); + if (!y) + return -ENOMEM; + + WITH_UMASK(0000) + if (mkdir(y, 0777 | S_ISVTX) < 0) + return -errno; + + r = label_fix_full(AT_FDCWD, y, prefix, 0); + if (r < 0) + return r; + + if (tmp_path) + *tmp_path = TAKE_PTR(y); + } else { + /* Trouble: we failed to create the directory. Instead of failing, let's simulate /tmp being + * read-only. This way the service will get the EROFS result as if it was writing to the real + * file system. */ + WITH_UMASK(0000) + r = mkdir_p(RUN_SYSTEMD_EMPTY, 0500); + if (r < 0) + return r; + + r = free_and_strdup(&x, RUN_SYSTEMD_EMPTY); + if (r < 0) + return r; + } + + *path = TAKE_PTR(x); + return 0; +} + +int setup_tmp_dirs(const char *id, char **tmp_dir, char **var_tmp_dir) { + _cleanup_(namespace_cleanup_tmpdirp) char *a = NULL; + _cleanup_(rmdir_and_freep) char *a_tmp = NULL; + char *b; + int r; + + assert(id); + assert(tmp_dir); + assert(var_tmp_dir); + + r = setup_one_tmp_dir(id, "/tmp", &a, &a_tmp); + if (r < 0) + return r; + + r = setup_one_tmp_dir(id, "/var/tmp", &b, NULL); + if (r < 0) + return r; + + a_tmp = mfree(a_tmp); /* avoid rmdir */ + *tmp_dir = TAKE_PTR(a); + *var_tmp_dir = TAKE_PTR(b); + + return 0; +} + +int setup_shareable_ns(int ns_storage_socket[static 2], unsigned long nsflag) { + _cleanup_close_ int ns = -EBADF; + const char *ns_name, *ns_path; + int r; + + assert(ns_storage_socket); + assert(ns_storage_socket[0] >= 0); + assert(ns_storage_socket[1] >= 0); + + ns_name = ASSERT_PTR(namespace_single_flag_to_string(nsflag)); + + /* 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! */ + + r = posix_lock(ns_storage_socket[0], LOCK_EX); + if (r < 0) + return r; + + CLEANUP_POSIX_UNLOCK(ns_storage_socket[0]); + + ns = receive_one_fd(ns_storage_socket[0], MSG_PEEK|MSG_DONTWAIT); + if (ns >= 0) { + /* Yay, found something, so let's join the namespace */ + r = RET_NERRNO(setns(ns, nsflag)); + if (r < 0) + return r; + + return 0; + } + + if (ns != -EAGAIN) + return ns; + + /* Nothing stored yet, so let's create a new namespace. */ + + if (unshare(nsflag) < 0) + return -errno; + + if (nsflag == CLONE_NEWNET) + (void) loopback_setup(); + + ns_path = strjoina("/proc/self/ns/", ns_name); + ns = open(ns_path, O_RDONLY|O_CLOEXEC|O_NOCTTY); + if (ns < 0) + return -errno; + + r = send_one_fd(ns_storage_socket[1], ns, MSG_DONTWAIT); + if (r < 0) + return r; + + return 1; +} + +int open_shareable_ns_path(int ns_storage_socket[static 2], const char *path, unsigned long nsflag) { + _cleanup_close_ int ns = -EBADF; + int r; + + assert(ns_storage_socket); + assert(ns_storage_socket[0] >= 0); + assert(ns_storage_socket[1] >= 0); + assert(path); + + /* If the storage socket doesn't contain a ns fd yet, open one via the file system and store it in + * it. This is supposed to be called ahead of time, i.e. before setup_shareable_ns() which will + * allocate a new anonymous ns if needed. */ + + r = posix_lock(ns_storage_socket[0], LOCK_EX); + if (r < 0) + return r; + + CLEANUP_POSIX_UNLOCK(ns_storage_socket[0]); + + ns = receive_one_fd(ns_storage_socket[0], MSG_PEEK|MSG_DONTWAIT); + if (ns >= 0) + return 0; + if (ns != -EAGAIN) + return ns; + + /* Nothing stored yet. Open the file from the file system. */ + + ns = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC); + if (ns < 0) + return -errno; + + r = fd_is_ns(ns, nsflag); + if (r == 0) + return -EINVAL; + if (r < 0 && r != -EUCLEAN) /* EUCLEAN: we don't know */ + return r; + + r = send_one_fd(ns_storage_socket[1], ns, MSG_DONTWAIT); + if (r < 0) + return r; + + return 1; +} + +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", + [NAMESPACE_TIME] = "time", +}; + +DEFINE_STRING_TABLE_LOOKUP(namespace_type, NamespaceType); + +static const char* const protect_proc_table[_PROTECT_PROC_MAX] = { + [PROTECT_PROC_DEFAULT] = "default", + [PROTECT_PROC_NOACCESS] = "noaccess", + [PROTECT_PROC_INVISIBLE] = "invisible", + [PROTECT_PROC_PTRACEABLE] = "ptraceable", +}; + +DEFINE_STRING_TABLE_LOOKUP(protect_proc, ProtectProc); + +static const char* const proc_subset_table[_PROC_SUBSET_MAX] = { + [PROC_SUBSET_ALL] = "all", + [PROC_SUBSET_PID] = "pid", +}; + +DEFINE_STRING_TABLE_LOOKUP(proc_subset, ProcSubset); |