/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
Copyright 2016 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see .
***/
#include
#include
#include
#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 "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;
r = lock_fd;
lock_fd = -1;
return r;
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));
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control = {};
struct msghdr mh = {
.msg_control = &control,
.msg_controllen = sizeof(control),
.msg_iov = &iov,
.msg_iovlen = 1,
};
struct cmsghdr *cmsg;
ssize_t k;
int lock_fd = -1;
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 = recvmsg(d->storage_socket[0], &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
if (k < 0)
return -errno;
cmsg = cmsg_find(&mh, SOL_SOCKET, SCM_RIGHTS, CMSG_LEN(sizeof(int)));
if (cmsg)
lock_fd = *(int*) CMSG_DATA(cmsg);
else
cmsg_close_all(&mh); /* just in case... */
*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));
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control = {};
struct msghdr mh = {
.msg_control = &control,
.msg_controllen = sizeof(control),
.msg_iov = &iov,
.msg_iovlen = 1,
};
ssize_t k;
assert(d);
/* Store the UID and lock_fd in the storage socket. This should be called with the socket pair lock taken. */
if (lock_fd >= 0) {
struct cmsghdr *cmsg;
cmsg = CMSG_FIRSTHDR(&mh);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
memcpy(CMSG_DATA(cmsg), &lock_fd, sizeof(int));
mh.msg_controllen = CMSG_SPACE(sizeof(int));
} else {
mh.msg_control = NULL;
mh.msg_controllen = 0;
}
k = sendmsg(d->storage_socket[1], &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
if (k < 0)
return -errno;
return 0;
}
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);
}