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-rw-r--r--src/core/dynamic-user.c826
1 files changed, 826 insertions, 0 deletions
diff --git a/src/core/dynamic-user.c b/src/core/dynamic-user.c
new file mode 100644
index 0000000..18b36e7
--- /dev/null
+++ b/src/core/dynamic-user.c
@@ -0,0 +1,826 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "clean-ipc.h"
+#include "dynamic-user.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "format-util.h"
+#include "fs-util.h"
+#include "io-util.h"
+#include "nscd-flush.h"
+#include "parse-util.h"
+#include "random-util.h"
+#include "serialize.h"
+#include "socket-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "uid-alloc-range.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)
+
+DEFINE_PRIVATE_TRIVIAL_REF_FUNC(DynamicUser, dynamic_user);
+
+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[static 2], DynamicUser **ret) {
+ DynamicUser *d;
+ 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) {
+ if (ret) {
+ /* 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(name, VALID_USER_ALLOW_NUMERIC))
+ 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
+ * LogsDirectory= 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();
+ }
+
+ /* 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 */
+ bool flush_cache = false;
+ 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. */
+ flush_cache = true;
+ } 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;
+ }
+ } else if (is_user && !uid_is_dynamic(num)) {
+ struct passwd *p;
+
+ /* Statically allocated user may have different uid and gid. So, let's obtain the gid. */
+ errno = 0;
+ p = getpwuid(num);
+ if (!p)
+ return errno_or_else(ESRCH);
+
+ gid = p->pw_gid;
+ }
+
+ /* 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 (flush_cache) {
+ /* If we allocated a new dynamic UID, refresh nscd, so that it forgets about potentially cached
+ * negative entries. But let's do so after we release the /etc/passwd lock, so that there's no
+ * potential for nscd wanting to lock that for completing the invalidation. */
+ etc_passwd_lock_fd = safe_close(etc_passwd_lock_fd);
+ (void) nscd_flush_cache(STRV_MAKE("passwd", "group"));
+ }
+
+ 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);
+
+ /* 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;
+
+ if (ret)
+ *ret = uid;
+
+ return 0;
+}
+
+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);
+
+ (void) nscd_flush_cache(STRV_MAKE("passwd", "group"));
+ 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;
+
+ 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) {
+ int copy0, copy1;
+
+ copy0 = fdset_put_dup(fds, d->storage_socket[0]);
+ if (copy0 < 0)
+ return log_error_errno(copy0, "Failed to add dynamic user storage fd to serialization: %m");
+
+ copy1 = fdset_put_dup(fds, d->storage_socket[1]);
+ if (copy1 < 0)
+ return log_error_errno(copy1, "Failed to add dynamic user storage fd to serialization: %m");
+
+ (void) serialize_item_format(f, "dynamic-user", "%s %i %i", 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;
+
+ 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) {
+ 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 (IN_SET(r, -ENOENT, 0))
+ 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);
+
+ /* 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 if (group) {
+ 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);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 20:22:08 +0000