diff options
Diffstat (limited to 'src/home/homework-directory.c')
| -rw-r--r-- | src/home/homework-directory.c | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/src/home/homework-directory.c b/src/home/homework-directory.c new file mode 100644 index 0000000..6870ae9 --- /dev/null +++ b/src/home/homework-directory.c @@ -0,0 +1,313 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <sys/mount.h> + +#include "btrfs-util.h" +#include "fd-util.h" +#include "homework-directory.h" +#include "homework-mount.h" +#include "homework-quota.h" +#include "mkdir.h" +#include "mount-util.h" +#include "path-util.h" +#include "rm-rf.h" +#include "tmpfile-util.h" +#include "umask-util.h" +#include "user-util.h" + +int home_setup_directory(UserRecord *h, HomeSetup *setup) { + const char *ip; + int r; + + assert(h); + assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME)); + assert(setup); + assert(!setup->undo_mount); + assert(setup->root_fd < 0); + + /* We'll bind mount the image directory to a new mount point where we'll start adjusting it. Only + * once that's complete we'll move the thing to its final place eventually. */ + r = home_unshare_and_mkdir(); + if (r < 0) + return r; + + assert_se(ip = user_record_image_path(h)); + + r = mount_follow_verbose(LOG_ERR, ip, HOME_RUNTIME_WORK_DIR, NULL, MS_BIND, NULL); + if (r < 0) + return r; + + setup->undo_mount = true; + + /* Turn off any form of propagation for this */ + r = mount_nofollow_verbose(LOG_ERR, NULL, HOME_RUNTIME_WORK_DIR, NULL, MS_PRIVATE, NULL); + if (r < 0) + return r; + + /* Adjust MS_SUID and similar flags */ + r = mount_nofollow_verbose(LOG_ERR, NULL, HOME_RUNTIME_WORK_DIR, NULL, MS_BIND|MS_REMOUNT|user_record_mount_flags(h), NULL); + if (r < 0) + return r; + + setup->root_fd = open(HOME_RUNTIME_WORK_DIR, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW); + if (setup->root_fd < 0) + return log_error_errno(errno, "Failed to open home directory: %m"); + + return 0; +} + +int home_activate_directory( + UserRecord *h, + HomeSetupFlags flags, + HomeSetup *setup, + PasswordCache *cache, + UserRecord **ret_home) { + + _cleanup_(user_record_unrefp) UserRecord *new_home = NULL, *header_home = NULL; + const char *hd, *hdo; + int r; + + assert(h); + assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME, USER_FSCRYPT)); + assert(setup); + assert(ret_home); + + assert_se(hdo = user_record_home_directory(h)); + hd = strdupa_safe(hdo); + + r = home_setup(h, flags, setup, cache, &header_home); + if (r < 0) + return r; + + r = home_refresh(h, flags, setup, header_home, cache, NULL, &new_home); + if (r < 0) + return r; + + r = home_extend_embedded_identity(new_home, h, setup); + if (r < 0) + return r; + + /* Close fd to private mount before moving mount */ + setup->root_fd = safe_close(setup->root_fd); + + /* We are now done with everything, move the mount into place */ + r = home_move_mount(NULL, hd); + if (r < 0) + return r; + + setup->undo_mount = false; + + setup->do_drop_caches = false; + + log_info("Everything completed."); + + *ret_home = TAKE_PTR(new_home); + return 0; +} + +int home_create_directory_or_subvolume(UserRecord *h, HomeSetup *setup, UserRecord **ret_home) { + _cleanup_(rm_rf_subvolume_and_freep) char *temporary = NULL; + _cleanup_(user_record_unrefp) UserRecord *new_home = NULL; + _cleanup_close_ int mount_fd = -EBADF; + _cleanup_free_ char *d = NULL; + bool is_subvolume = false; + const char *ip; + int r; + + assert(h); + assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME)); + assert(setup); + assert(ret_home); + + assert_se(ip = user_record_image_path(h)); + + r = tempfn_random(ip, "homework", &d); + if (r < 0) + return log_error_errno(r, "Failed to allocate temporary directory: %m"); + + (void) mkdir_parents(d, 0755); + + switch (user_record_storage(h)) { + + case USER_SUBVOLUME: + WITH_UMASK(0077) + r = btrfs_subvol_make(AT_FDCWD, d); + + if (r >= 0) { + log_info("Subvolume created."); + is_subvolume = true; + + if (h->disk_size != UINT64_MAX) { + + /* Enable quota for the subvolume we just created. Note we don't check for + * errors here and only log about debug level about this. */ + r = btrfs_quota_enable(d, true); + if (r < 0) + log_debug_errno(r, "Failed to enable quota on %s, ignoring: %m", d); + + r = btrfs_subvol_auto_qgroup(d, 0, false); + if (r < 0) + log_debug_errno(r, "Failed to set up automatic quota group on %s, ignoring: %m", d); + + /* Actually configure the quota. We also ignore errors here, but we do log + * about them loudly, to keep things discoverable even though we don't + * consider lacking quota support in kernel fatal. */ + (void) home_update_quota_btrfs(h, d); + } + + break; + } + if (r != -ENOTTY) + return log_error_errno(r, "Failed to create temporary home directory subvolume %s: %m", d); + + log_info("Creating subvolume %s is not supported, as file system does not support subvolumes. Falling back to regular directory.", d); + _fallthrough_; + + case USER_DIRECTORY: + + if (mkdir(d, 0700) < 0) + return log_error_errno(errno, "Failed to create temporary home directory %s: %m", d); + + (void) home_update_quota_classic(h, d); + break; + + default: + assert_not_reached(); + } + + temporary = TAKE_PTR(d); /* Needs to be destroyed now */ + + /* Let's decouple namespaces now, so that we can possibly mount a UID map mount into + * /run/systemd/user-home-mount/ that no one will see but us. */ + r = home_unshare_and_mkdir(); + if (r < 0) + return r; + + setup->root_fd = open(temporary, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW); + if (setup->root_fd < 0) + return log_error_errno(errno, "Failed to open temporary home directory: %m"); + + /* Try to apply a UID shift, so that the directory is actually owned by "nobody", and is only mapped + * to the proper UID while active. — Well, that's at least the theory. Unfortunately, only btrfs does + * per-subvolume quota. The others do per-uid quota. Which means mapping all home directories to the + * same UID of "nobody" makes quota impossible. Hence unless we actually managed to create a btrfs + * subvolume for this user we'll map the user's UID to itself. Now you might ask: why bother mapping + * at all? It's because we want to restrict the UIDs used on the home directory: we leave all other + * UIDs of the homed UID range unmapped, thus making them unavailable to programs accessing the + * mount. */ + r = home_shift_uid(setup->root_fd, HOME_RUNTIME_WORK_DIR, is_subvolume ? UID_NOBODY : h->uid, h->uid, &mount_fd); + if (r > 0) + setup->undo_mount = true; /* If uidmaps worked we have a mount to undo again */ + + if (mount_fd >= 0) { + /* If we have established a new mount, then we can use that as new root fd to our home directory. */ + safe_close(setup->root_fd); + + setup->root_fd = fd_reopen(mount_fd, O_RDONLY|O_CLOEXEC|O_DIRECTORY); + if (setup->root_fd < 0) + return log_error_errno(setup->root_fd, "Unable to convert mount fd into proper directory fd: %m"); + + mount_fd = safe_close(mount_fd); + } + + r = home_populate(h, setup->root_fd); + if (r < 0) + return r; + + r = home_sync_and_statfs(setup->root_fd, NULL); + if (r < 0) + return r; + + r = user_record_clone(h, USER_RECORD_LOAD_MASK_SECRET|USER_RECORD_PERMISSIVE, &new_home); + if (r < 0) + return log_error_errno(r, "Failed to clone record: %m"); + + r = user_record_add_binding( + new_home, + user_record_storage(h), + ip, + SD_ID128_NULL, + SD_ID128_NULL, + SD_ID128_NULL, + NULL, + NULL, + UINT64_MAX, + NULL, + NULL, + h->uid, + (gid_t) h->uid); + if (r < 0) + return log_error_errno(r, "Failed to add binding to record: %m"); + + setup->root_fd = safe_close(setup->root_fd); + + /* Unmount mapped mount before we move the dir into place */ + r = home_setup_undo_mount(setup, LOG_ERR); + if (r < 0) + return r; + + if (rename(temporary, ip) < 0) + return log_error_errno(errno, "Failed to rename %s to %s: %m", temporary, ip); + + temporary = mfree(temporary); + + log_info("Everything completed."); + + *ret_home = TAKE_PTR(new_home); + return 0; +} + +int home_resize_directory( + UserRecord *h, + HomeSetupFlags flags, + HomeSetup *setup, + PasswordCache *cache, + UserRecord **ret_home) { + + _cleanup_(user_record_unrefp) UserRecord *embedded_home = NULL, *new_home = NULL; + int r; + + assert(h); + assert(setup); + assert(ret_home); + assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME, USER_FSCRYPT)); + + r = home_setup(h, flags, setup, cache, NULL); + if (r < 0) + return r; + + r = home_load_embedded_identity(h, setup->root_fd, NULL, USER_RECONCILE_REQUIRE_NEWER_OR_EQUAL, cache, &embedded_home, &new_home); + if (r < 0) + return r; + + r = home_maybe_shift_uid(h, flags, setup); + if (r < 0) + return r; + + r = home_update_quota_auto(h, NULL); + if (ERRNO_IS_NEG_NOT_SUPPORTED(r)) + return -ESOCKTNOSUPPORT; /* make recognizable */ + if (r < 0) + return r; + + r = home_store_embedded_identity(new_home, setup->root_fd, h->uid, embedded_home); + if (r < 0) + return r; + + r = home_extend_embedded_identity(new_home, h, setup); + if (r < 0) + return r; + + r = home_sync_and_statfs(setup->root_fd, NULL); + if (r < 0) + return r; + + r = home_setup_done(setup); + if (r < 0) + return r; + + log_info("Everything completed."); + + *ret_home = TAKE_PTR(new_home); + return 0; +} |