| /* SPDX-License-Identifier: LGPL-2.1+ */ |
| |
| #include <grp.h> |
| #include <pwd.h> |
| #include <sys/file.h> |
| |
| #include "clean-ipc.h" |
| #include "dynamic-user.h" |
| #include "fd-util.h" |
| #include "fileio.h" |
| #include "fs-util.h" |
| #include "io-util.h" |
| #include "parse-util.h" |
| #include "random-util.h" |
| #include "socket-util.h" |
| #include "stdio-util.h" |
| #include "string-util.h" |
| #include "user-util.h" |
| |
| /* Takes a value generated randomly or by hashing and turns it into a UID in the right range */ |
| #define UID_CLAMP_INTO_RANGE(rnd) (((uid_t) (rnd) % (DYNAMIC_UID_MAX - DYNAMIC_UID_MIN + 1)) + DYNAMIC_UID_MIN) |
| |
| static DynamicUser* dynamic_user_free(DynamicUser *d) { |
| if (!d) |
| return NULL; |
| |
| if (d->manager) |
| (void) hashmap_remove(d->manager->dynamic_users, d->name); |
| |
| safe_close_pair(d->storage_socket); |
| return mfree(d); |
| } |
| |
| static int dynamic_user_add(Manager *m, const char *name, int storage_socket[2], DynamicUser **ret) { |
| DynamicUser *d = NULL; |
| int r; |
| |
| assert(m); |
| assert(name); |
| assert(storage_socket); |
| |
| r = hashmap_ensure_allocated(&m->dynamic_users, &string_hash_ops); |
| if (r < 0) |
| return r; |
| |
| d = malloc0(offsetof(DynamicUser, name) + strlen(name) + 1); |
| if (!d) |
| return -ENOMEM; |
| |
| strcpy(d->name, name); |
| |
| d->storage_socket[0] = storage_socket[0]; |
| d->storage_socket[1] = storage_socket[1]; |
| |
| r = hashmap_put(m->dynamic_users, d->name, d); |
| if (r < 0) { |
| free(d); |
| return r; |
| } |
| |
| d->manager = m; |
| |
| if (ret) |
| *ret = d; |
| |
| return 0; |
| } |
| |
| static int dynamic_user_acquire(Manager *m, const char *name, DynamicUser** ret) { |
| _cleanup_close_pair_ int storage_socket[2] = { -1, -1 }; |
| DynamicUser *d; |
| int r; |
| |
| assert(m); |
| assert(name); |
| |
| /* Return the DynamicUser structure for a specific user name. Note that this won't actually allocate a UID for |
| * it, but just prepare the data structure for it. The UID is allocated only on demand, when it's really |
| * needed, and in the child process we fork off, since allocation involves NSS checks which are not OK to do |
| * from PID 1. To allow the children and PID 1 share information about allocated UIDs we use an anonymous |
| * AF_UNIX/SOCK_DGRAM socket (called the "storage socket") that contains at most one datagram with the |
| * allocated UID number, plus an fd referencing the lock file for the UID |
| * (i.e. /run/systemd/dynamic-uid/$UID). Why involve the socket pair? So that PID 1 and all its children can |
| * share the same storage for the UID and lock fd, simply by inheriting the storage socket fds. The socket pair |
| * may exist in three different states: |
| * |
| * a) no datagram stored. This is the initial state. In this case the dynamic user was never realized. |
| * |
| * b) a datagram containing a UID stored, but no lock fd attached to it. In this case there was already a |
| * statically assigned UID by the same name, which we are reusing. |
| * |
| * c) a datagram containing a UID stored, and a lock fd is attached to it. In this case we allocated a dynamic |
| * UID and locked it in the file system, using the lock fd. |
| * |
| * As PID 1 and various children might access the socket pair simultaneously, and pop the datagram or push it |
| * back in any time, we also maintain a lock on the socket pair. Note one peculiarity regarding locking here: |
| * the UID lock on disk is protected via a BSD file lock (i.e. an fd-bound lock), so that the lock is kept in |
| * place as long as there's a reference to the fd open. The lock on the storage socket pair however is a POSIX |
| * file lock (i.e. a process-bound lock), as all users share the same fd of this (after all it is anonymous, |
| * nobody else could get any access to it except via our own fd) and we want to synchronize access between all |
| * processes that have access to it. */ |
| |
| d = hashmap_get(m->dynamic_users, name); |
| if (d) { |
| /* We already have a structure for the dynamic user, let's increase the ref count and reuse it */ |
| d->n_ref++; |
| *ret = d; |
| return 0; |
| } |
| |
| if (!valid_user_group_name_or_id(name)) |
| return -EINVAL; |
| |
| if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0, storage_socket) < 0) |
| return -errno; |
| |
| r = dynamic_user_add(m, name, storage_socket, &d); |
| if (r < 0) |
| return r; |
| |
| storage_socket[0] = storage_socket[1] = -1; |
| |
| if (ret) { |
| d->n_ref++; |
| *ret = d; |
| } |
| |
| return 1; |
| } |
| |
| static int make_uid_symlinks(uid_t uid, const char *name, bool b) { |
| |
| char path1[STRLEN("/run/systemd/dynamic-uid/direct:") + DECIMAL_STR_MAX(uid_t) + 1]; |
| const char *path2; |
| int r = 0, k; |
| |
| /* Add direct additional symlinks for direct lookups of dynamic UIDs and their names by userspace code. The |
| * only reason we have this is because dbus-daemon cannot use D-Bus for resolving users and groups (since it |
| * would be its own client then). We hence keep these world-readable symlinks in place, so that the |
| * unprivileged dbus user can read the mappings when it needs them via these symlinks instead of having to go |
| * via the bus. Ideally, we'd use the lock files we keep for this anyway, but we can't since we use BSD locks |
| * on them and as those may be taken by any user with read access we can't make them world-readable. */ |
| |
| xsprintf(path1, "/run/systemd/dynamic-uid/direct:" UID_FMT, uid); |
| if (unlink(path1) < 0 && errno != ENOENT) |
| r = -errno; |
| |
| if (b && symlink(name, path1) < 0) { |
| k = log_warning_errno(errno, "Failed to symlink \"%s\": %m", path1); |
| if (r == 0) |
| r = k; |
| } |
| |
| path2 = strjoina("/run/systemd/dynamic-uid/direct:", name); |
| if (unlink(path2) < 0 && errno != ENOENT) { |
| k = -errno; |
| if (r == 0) |
| r = k; |
| } |
| |
| if (b && symlink(path1 + STRLEN("/run/systemd/dynamic-uid/direct:"), path2) < 0) { |
| k = log_warning_errno(errno, "Failed to symlink \"%s\": %m", path2); |
| if (r == 0) |
| r = k; |
| } |
| |
| return r; |
| } |
| |
| static int pick_uid(char **suggested_paths, const char *name, uid_t *ret_uid) { |
| |
| /* Find a suitable free UID. We use the following strategy to find a suitable UID: |
| * |
| * 1. Initially, we try to read the UID of a number of specified paths. If any of these UIDs works, we use |
| * them. We use in order to increase the chance of UID reuse, if StateDirectory=, CacheDirectory= or |
| * LogDirectory= are used, as reusing the UID these directories are owned by saves us from having to |
| * recursively chown() them to new users. |
| * |
| * 2. If that didn't yield a currently unused UID, we hash the user name, and try to use that. This should be |
| * pretty good, as the use ris by default derived from the unit name, and hence the same service and same |
| * user should usually get the same UID as long as our hashing doesn't clash. |
| * |
| * 3. Finally, if that didn't work, we randomly pick UIDs, until we find one that is empty. |
| * |
| * Since the dynamic UID space is relatively small we'll stop trying after 100 iterations, giving up. */ |
| |
| enum { |
| PHASE_SUGGESTED, /* the first phase, reusing directory ownership UIDs */ |
| PHASE_HASHED, /* the second phase, deriving a UID from the username by hashing */ |
| PHASE_RANDOM, /* the last phase, randomly picking UIDs */ |
| } phase = PHASE_SUGGESTED; |
| |
| static const uint8_t hash_key[] = { |
| 0x37, 0x53, 0x7e, 0x31, 0xcf, 0xce, 0x48, 0xf5, |
| 0x8a, 0xbb, 0x39, 0x57, 0x8d, 0xd9, 0xec, 0x59 |
| }; |
| |
| unsigned n_tries = 100, current_suggested = 0; |
| int r; |
| |
| (void) mkdir("/run/systemd/dynamic-uid", 0755); |
| |
| for (;;) { |
| char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
| _cleanup_close_ int lock_fd = -1; |
| uid_t candidate; |
| ssize_t l; |
| |
| if (--n_tries <= 0) /* Give up retrying eventually */ |
| return -EBUSY; |
| |
| switch (phase) { |
| |
| case PHASE_SUGGESTED: { |
| struct stat st; |
| |
| if (!suggested_paths || !suggested_paths[current_suggested]) { |
| /* We reached the end of the suggested paths list, let's try by hashing the name */ |
| phase = PHASE_HASHED; |
| continue; |
| } |
| |
| if (stat(suggested_paths[current_suggested++], &st) < 0) |
| continue; /* We can't read the UID of this path, but that doesn't matter, just try the next */ |
| |
| candidate = st.st_uid; |
| break; |
| } |
| |
| case PHASE_HASHED: |
| /* A static user by this name does not exist yet. Let's find a free ID then, and use that. We |
| * start with a UID generated as hash from the user name. */ |
| candidate = UID_CLAMP_INTO_RANGE(siphash24(name, strlen(name), hash_key)); |
| |
| /* If this one fails, we should proceed with random tries */ |
| phase = PHASE_RANDOM; |
| break; |
| |
| case PHASE_RANDOM: |
| |
| /* Pick another random UID, and see if that works for us. */ |
| random_bytes(&candidate, sizeof(candidate)); |
| candidate = UID_CLAMP_INTO_RANGE(candidate); |
| break; |
| |
| default: |
| assert_not_reached("unknown phase"); |
| } |
| |
| /* Make sure whatever we picked here actually is in the right range */ |
| if (!uid_is_dynamic(candidate)) |
| continue; |
| |
| xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, candidate); |
| |
| for (;;) { |
| struct stat st; |
| |
| lock_fd = open(lock_path, O_CREAT|O_RDWR|O_NOFOLLOW|O_CLOEXEC|O_NOCTTY, 0600); |
| if (lock_fd < 0) |
| return -errno; |
| |
| r = flock(lock_fd, LOCK_EX|LOCK_NB); /* Try to get a BSD file lock on the UID lock file */ |
| if (r < 0) { |
| if (IN_SET(errno, EBUSY, EAGAIN)) |
| goto next; /* already in use */ |
| |
| return -errno; |
| } |
| |
| if (fstat(lock_fd, &st) < 0) |
| return -errno; |
| if (st.st_nlink > 0) |
| break; |
| |
| /* Oh, bummer, we got the lock, but the file was unlinked between the time we opened it and |
| * got the lock. Close it, and try again. */ |
| lock_fd = safe_close(lock_fd); |
| } |
| |
| /* Some superficial check whether this UID/GID might already be taken by some static user */ |
| if (getpwuid(candidate) || |
| getgrgid((gid_t) candidate) || |
| search_ipc(candidate, (gid_t) candidate) != 0) { |
| (void) unlink(lock_path); |
| continue; |
| } |
| |
| /* Let's store the user name in the lock file, so that we can use it for looking up the username for a UID */ |
| l = pwritev(lock_fd, |
| (struct iovec[2]) { |
| IOVEC_INIT_STRING(name), |
| IOVEC_INIT((char[1]) { '\n' }, 1), |
| }, 2, 0); |
| if (l < 0) { |
| r = -errno; |
| (void) unlink(lock_path); |
| return r; |
| } |
| |
| (void) ftruncate(lock_fd, l); |
| (void) make_uid_symlinks(candidate, name, true); /* also add direct lookup symlinks */ |
| |
| *ret_uid = candidate; |
| return TAKE_FD(lock_fd); |
| |
| next: |
| ; |
| } |
| } |
| |
| static int dynamic_user_pop(DynamicUser *d, uid_t *ret_uid, int *ret_lock_fd) { |
| uid_t uid = UID_INVALID; |
| struct iovec iov = IOVEC_INIT(&uid, sizeof(uid)); |
| int lock_fd; |
| ssize_t k; |
| |
| assert(d); |
| assert(ret_uid); |
| assert(ret_lock_fd); |
| |
| /* Read the UID and lock fd that is stored in the storage AF_UNIX socket. This should be called with the lock |
| * on the socket taken. */ |
| |
| k = receive_one_fd_iov(d->storage_socket[0], &iov, 1, MSG_DONTWAIT, &lock_fd); |
| if (k < 0) |
| return (int) k; |
| |
| *ret_uid = uid; |
| *ret_lock_fd = lock_fd; |
| |
| return 0; |
| } |
| |
| static int dynamic_user_push(DynamicUser *d, uid_t uid, int lock_fd) { |
| struct iovec iov = IOVEC_INIT(&uid, sizeof(uid)); |
| |
| assert(d); |
| |
| /* Store the UID and lock_fd in the storage socket. This should be called with the socket pair lock taken. */ |
| return send_one_fd_iov(d->storage_socket[1], lock_fd, &iov, 1, MSG_DONTWAIT); |
| } |
| |
| static void unlink_uid_lock(int lock_fd, uid_t uid, const char *name) { |
| char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
| |
| if (lock_fd < 0) |
| return; |
| |
| xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, uid); |
| (void) unlink(lock_path); |
| |
| (void) make_uid_symlinks(uid, name, false); /* remove direct lookup symlinks */ |
| } |
| |
| static int lockfp(int fd, int *fd_lock) { |
| if (lockf(fd, F_LOCK, 0) < 0) |
| return -errno; |
| *fd_lock = fd; |
| return 0; |
| } |
| |
| static void unlockfp(int *fd_lock) { |
| if (*fd_lock < 0) |
| return; |
| lockf(*fd_lock, F_ULOCK, 0); |
| *fd_lock = -1; |
| } |
| |
| static int dynamic_user_realize( |
| DynamicUser *d, |
| char **suggested_dirs, |
| uid_t *ret_uid, gid_t *ret_gid, |
| bool is_user) { |
| |
| _cleanup_(unlockfp) int storage_socket0_lock = -1; |
| _cleanup_close_ int uid_lock_fd = -1; |
| _cleanup_close_ int etc_passwd_lock_fd = -1; |
| uid_t num = UID_INVALID; /* a uid if is_user, and a gid otherwise */ |
| gid_t gid = GID_INVALID; /* a gid if is_user, ignored otherwise */ |
| int r; |
| |
| assert(d); |
| assert(is_user == !!ret_uid); |
| assert(ret_gid); |
| |
| /* Acquire a UID for the user name. This will allocate a UID for the user name if the user doesn't exist |
| * yet. If it already exists its existing UID/GID will be reused. */ |
| |
| r = lockfp(d->storage_socket[0], &storage_socket0_lock); |
| if (r < 0) |
| return r; |
| |
| r = dynamic_user_pop(d, &num, &uid_lock_fd); |
| if (r < 0) { |
| int new_uid_lock_fd; |
| uid_t new_uid; |
| |
| if (r != -EAGAIN) |
| return r; |
| |
| /* OK, nothing stored yet, let's try to find something useful. While we are working on this release the |
| * lock however, so that nobody else blocks on our NSS lookups. */ |
| unlockfp(&storage_socket0_lock); |
| |
| /* Let's see if a proper, static user or group by this name exists. Try to take the lock on |
| * /etc/passwd, if that fails with EROFS then /etc is read-only. In that case it's fine if we don't |
| * take the lock, given that users can't be added there anyway in this case. */ |
| etc_passwd_lock_fd = take_etc_passwd_lock(NULL); |
| if (etc_passwd_lock_fd < 0 && etc_passwd_lock_fd != -EROFS) |
| return etc_passwd_lock_fd; |
| |
| /* First, let's parse this as numeric UID */ |
| r = parse_uid(d->name, &num); |
| if (r < 0) { |
| struct passwd *p; |
| struct group *g; |
| |
| if (is_user) { |
| /* OK, this is not a numeric UID. Let's see if there's a user by this name */ |
| p = getpwnam(d->name); |
| if (p) { |
| num = p->pw_uid; |
| gid = p->pw_gid; |
| } else { |
| /* if the user does not exist but the group with the same name exists, refuse operation */ |
| g = getgrnam(d->name); |
| if (g) |
| return -EILSEQ; |
| } |
| } else { |
| /* Let's see if there's a group by this name */ |
| g = getgrnam(d->name); |
| if (g) |
| num = (uid_t) g->gr_gid; |
| else { |
| /* if the group does not exist but the user with the same name exists, refuse operation */ |
| p = getpwnam(d->name); |
| if (p) |
| return -EILSEQ; |
| } |
| } |
| } |
| |
| if (num == UID_INVALID) { |
| /* No static UID assigned yet, excellent. Let's pick a new dynamic one, and lock it. */ |
| |
| uid_lock_fd = pick_uid(suggested_dirs, d->name, &num); |
| if (uid_lock_fd < 0) |
| return uid_lock_fd; |
| } |
| |
| /* So, we found a working UID/lock combination. Let's see if we actually still need it. */ |
| r = lockfp(d->storage_socket[0], &storage_socket0_lock); |
| if (r < 0) { |
| unlink_uid_lock(uid_lock_fd, num, d->name); |
| return r; |
| } |
| |
| r = dynamic_user_pop(d, &new_uid, &new_uid_lock_fd); |
| if (r < 0) { |
| if (r != -EAGAIN) { |
| /* OK, something bad happened, let's get rid of the bits we acquired. */ |
| unlink_uid_lock(uid_lock_fd, num, d->name); |
| return r; |
| } |
| |
| /* Great! Nothing is stored here, still. Store our newly acquired data. */ |
| } else { |
| /* Hmm, so as it appears there's now something stored in the storage socket. Throw away what we |
| * acquired, and use what's stored now. */ |
| |
| unlink_uid_lock(uid_lock_fd, num, d->name); |
| safe_close(uid_lock_fd); |
| |
| num = new_uid; |
| uid_lock_fd = new_uid_lock_fd; |
| } |
| } |
| |
| /* If the UID/GID was already allocated dynamically, push the data we popped out back in. If it was already |
| * allocated statically, push the UID back too, but do not push the lock fd in. If we allocated the UID |
| * dynamically right here, push that in along with the lock fd for it. */ |
| r = dynamic_user_push(d, num, uid_lock_fd); |
| if (r < 0) |
| return r; |
| |
| if (is_user) { |
| *ret_uid = num; |
| *ret_gid = gid != GID_INVALID ? gid : num; |
| } else |
| *ret_gid = num; |
| |
| return 0; |
| } |
| |
| int dynamic_user_current(DynamicUser *d, uid_t *ret) { |
| _cleanup_(unlockfp) int storage_socket0_lock = -1; |
| _cleanup_close_ int lock_fd = -1; |
| uid_t uid; |
| int r; |
| |
| assert(d); |
| assert(ret); |
| |
| /* Get the currently assigned UID for the user, if there's any. This simply pops the data from the storage socket, and pushes it back in right-away. */ |
| |
| r = lockfp(d->storage_socket[0], &storage_socket0_lock); |
| if (r < 0) |
| return r; |
| |
| r = dynamic_user_pop(d, &uid, &lock_fd); |
| if (r < 0) |
| return r; |
| |
| r = dynamic_user_push(d, uid, lock_fd); |
| if (r < 0) |
| return r; |
| |
| *ret = uid; |
| return 0; |
| } |
| |
| static DynamicUser* dynamic_user_ref(DynamicUser *d) { |
| if (!d) |
| return NULL; |
| |
| assert(d->n_ref > 0); |
| d->n_ref++; |
| |
| return d; |
| } |
| |
| static DynamicUser* dynamic_user_unref(DynamicUser *d) { |
| if (!d) |
| return NULL; |
| |
| /* Note that this doesn't actually release any resources itself. If a dynamic user should be fully destroyed |
| * and its UID released, use dynamic_user_destroy() instead. NB: the dynamic user table may contain entries |
| * with no references, which is commonly the case right before a daemon reload. */ |
| |
| assert(d->n_ref > 0); |
| d->n_ref--; |
| |
| return NULL; |
| } |
| |
| static int dynamic_user_close(DynamicUser *d) { |
| _cleanup_(unlockfp) int storage_socket0_lock = -1; |
| _cleanup_close_ int lock_fd = -1; |
| uid_t uid; |
| int r; |
| |
| /* Release the user ID, by releasing the lock on it, and emptying the storage socket. After this the user is |
| * unrealized again, much like it was after it the DynamicUser object was first allocated. */ |
| |
| r = lockfp(d->storage_socket[0], &storage_socket0_lock); |
| if (r < 0) |
| return r; |
| |
| r = dynamic_user_pop(d, &uid, &lock_fd); |
| if (r == -EAGAIN) |
| /* User wasn't realized yet, nothing to do. */ |
| return 0; |
| if (r < 0) |
| return r; |
| |
| /* This dynamic user was realized and dynamically allocated. In this case, let's remove the lock file. */ |
| unlink_uid_lock(lock_fd, uid, d->name); |
| return 1; |
| } |
| |
| static DynamicUser* dynamic_user_destroy(DynamicUser *d) { |
| if (!d) |
| return NULL; |
| |
| /* Drop a reference to a DynamicUser object, and destroy the user completely if this was the last |
| * reference. This is called whenever a service is shut down and wants its dynamic UID gone. Note that |
| * dynamic_user_unref() is what is called whenever a service is simply freed, for example during a reload |
| * cycle, where the dynamic users should not be destroyed, but our datastructures should. */ |
| |
| dynamic_user_unref(d); |
| |
| if (d->n_ref > 0) |
| return NULL; |
| |
| (void) dynamic_user_close(d); |
| return dynamic_user_free(d); |
| } |
| |
| int dynamic_user_serialize(Manager *m, FILE *f, FDSet *fds) { |
| DynamicUser *d; |
| Iterator i; |
| |
| assert(m); |
| assert(f); |
| assert(fds); |
| |
| /* Dump the dynamic user database into the manager serialization, to deal with daemon reloads. */ |
| |
| HASHMAP_FOREACH(d, m->dynamic_users, i) { |
| int copy0, copy1; |
| |
| copy0 = fdset_put_dup(fds, d->storage_socket[0]); |
| if (copy0 < 0) |
| return copy0; |
| |
| copy1 = fdset_put_dup(fds, d->storage_socket[1]); |
| if (copy1 < 0) |
| return copy1; |
| |
| fprintf(f, "dynamic-user=%s %i %i\n", d->name, copy0, copy1); |
| } |
| |
| return 0; |
| } |
| |
| void dynamic_user_deserialize_one(Manager *m, const char *value, FDSet *fds) { |
| _cleanup_free_ char *name = NULL, *s0 = NULL, *s1 = NULL; |
| int r, fd0, fd1; |
| |
| assert(m); |
| assert(value); |
| assert(fds); |
| |
| /* Parse the serialization again, after a daemon reload */ |
| |
| r = extract_many_words(&value, NULL, 0, &name, &s0, &s1, NULL); |
| if (r != 3 || !isempty(value)) { |
| log_debug("Unable to parse dynamic user line."); |
| return; |
| } |
| |
| if (safe_atoi(s0, &fd0) < 0 || !fdset_contains(fds, fd0)) { |
| log_debug("Unable to process dynamic user fd specification."); |
| return; |
| } |
| |
| if (safe_atoi(s1, &fd1) < 0 || !fdset_contains(fds, fd1)) { |
| log_debug("Unable to process dynamic user fd specification."); |
| return; |
| } |
| |
| r = dynamic_user_add(m, name, (int[]) { fd0, fd1 }, NULL); |
| if (r < 0) { |
| log_debug_errno(r, "Failed to add dynamic user: %m"); |
| return; |
| } |
| |
| (void) fdset_remove(fds, fd0); |
| (void) fdset_remove(fds, fd1); |
| } |
| |
| void dynamic_user_vacuum(Manager *m, bool close_user) { |
| DynamicUser *d; |
| Iterator i; |
| |
| assert(m); |
| |
| /* Empty the dynamic user database, optionally cleaning up orphaned dynamic users, i.e. destroy and free users |
| * to which no reference exist. This is called after a daemon reload finished, in order to destroy users which |
| * might not be referenced anymore. */ |
| |
| HASHMAP_FOREACH(d, m->dynamic_users, i) { |
| if (d->n_ref > 0) |
| continue; |
| |
| if (close_user) { |
| log_debug("Removing orphaned dynamic user %s", d->name); |
| (void) dynamic_user_close(d); |
| } |
| |
| dynamic_user_free(d); |
| } |
| } |
| |
| int dynamic_user_lookup_uid(Manager *m, uid_t uid, char **ret) { |
| char lock_path[STRLEN("/run/systemd/dynamic-uid/") + DECIMAL_STR_MAX(uid_t) + 1]; |
| _cleanup_free_ char *user = NULL; |
| uid_t check_uid; |
| int r; |
| |
| assert(m); |
| assert(ret); |
| |
| /* A friendly way to translate a dynamic user's UID into a name. */ |
| if (!uid_is_dynamic(uid)) |
| return -ESRCH; |
| |
| xsprintf(lock_path, "/run/systemd/dynamic-uid/" UID_FMT, uid); |
| r = read_one_line_file(lock_path, &user); |
| if (r == -ENOENT) |
| return -ESRCH; |
| if (r < 0) |
| return r; |
| |
| /* The lock file might be stale, hence let's verify the data before we return it */ |
| r = dynamic_user_lookup_name(m, user, &check_uid); |
| if (r < 0) |
| return r; |
| if (check_uid != uid) /* lock file doesn't match our own idea */ |
| return -ESRCH; |
| |
| *ret = TAKE_PTR(user); |
| |
| return 0; |
| } |
| |
| int dynamic_user_lookup_name(Manager *m, const char *name, uid_t *ret) { |
| DynamicUser *d; |
| int r; |
| |
| assert(m); |
| assert(name); |
| assert(ret); |
| |
| /* A friendly call for translating a dynamic user's name into its UID */ |
| |
| d = hashmap_get(m->dynamic_users, name); |
| if (!d) |
| return -ESRCH; |
| |
| r = dynamic_user_current(d, ret); |
| if (r == -EAGAIN) /* not realized yet? */ |
| return -ESRCH; |
| |
| return r; |
| } |
| |
| int dynamic_creds_acquire(DynamicCreds *creds, Manager *m, const char *user, const char *group) { |
| bool acquired = false; |
| int r; |
| |
| assert(creds); |
| assert(m); |
| |
| /* A DynamicUser object encapsulates an allocation of both a UID and a GID for a specific name. However, some |
| * services use different user and groups. For cases like that there's DynamicCreds containing a pair of user |
| * and group. This call allocates a pair. */ |
| |
| if (!creds->user && user) { |
| r = dynamic_user_acquire(m, user, &creds->user); |
| if (r < 0) |
| return r; |
| |
| acquired = true; |
| } |
| |
| if (!creds->group) { |
| |
| if (creds->user && (!group || streq_ptr(user, group))) |
| creds->group = dynamic_user_ref(creds->user); |
| else { |
| r = dynamic_user_acquire(m, group, &creds->group); |
| if (r < 0) { |
| if (acquired) |
| creds->user = dynamic_user_unref(creds->user); |
| return r; |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| int dynamic_creds_realize(DynamicCreds *creds, char **suggested_paths, uid_t *uid, gid_t *gid) { |
| uid_t u = UID_INVALID; |
| gid_t g = GID_INVALID; |
| int r; |
| |
| assert(creds); |
| assert(uid); |
| assert(gid); |
| |
| /* Realize both the referenced user and group */ |
| |
| if (creds->user) { |
| r = dynamic_user_realize(creds->user, suggested_paths, &u, &g, true); |
| if (r < 0) |
| return r; |
| } |
| |
| if (creds->group && creds->group != creds->user) { |
| r = dynamic_user_realize(creds->group, suggested_paths, NULL, &g, false); |
| if (r < 0) |
| return r; |
| } |
| |
| *uid = u; |
| *gid = g; |
| return 0; |
| } |
| |
| void dynamic_creds_unref(DynamicCreds *creds) { |
| assert(creds); |
| |
| creds->user = dynamic_user_unref(creds->user); |
| creds->group = dynamic_user_unref(creds->group); |
| } |
| |
| void dynamic_creds_destroy(DynamicCreds *creds) { |
| assert(creds); |
| |
| creds->user = dynamic_user_destroy(creds->user); |
| creds->group = dynamic_user_destroy(creds->group); |
| } |