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bus-util.c
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600 lines (474 loc) · 18.4 KB
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <unistd.h>
#include "sd-bus.h"
#include "sd-daemon.h"
#include "sd-event.h"
#include "sd-id128.h"
#include "bus-common-errors.h"
#include "bus-internal.h"
#include "bus-label.h"
#include "bus-util.h"
#include "path-util.h"
#include "socket-util.h"
#include "stdio-util.h"
static int name_owner_change_callback(sd_bus_message *m, void *userdata, sd_bus_error *ret_error) {
sd_event *e = userdata;
assert(m);
assert(e);
sd_bus_close(sd_bus_message_get_bus(m));
sd_event_exit(e, 0);
return 1;
}
int bus_log_address_error(int r, BusTransport transport) {
bool hint = transport == BUS_TRANSPORT_LOCAL && r == -ENOMEDIUM;
return log_error_errno(r,
hint ? "Failed to set bus address: $DBUS_SESSION_BUS_ADDRESS and $XDG_RUNTIME_DIR not defined (consider using --machine=<user>@.host --user to connect to bus of other user)" :
"Failed to set bus address: %m");
}
int bus_log_connect_error(int r, BusTransport transport) {
bool hint_vars = transport == BUS_TRANSPORT_LOCAL && r == -ENOMEDIUM,
hint_addr = transport == BUS_TRANSPORT_LOCAL && ERRNO_IS_PRIVILEGE(r);
return log_error_errno(r,
r == hint_vars ? "Failed to connect to bus: $DBUS_SESSION_BUS_ADDRESS and $XDG_RUNTIME_DIR not defined (consider using --machine=<user>@.host --user to connect to bus of other user)" :
r == hint_addr ? "Failed to connect to bus: Operation not permitted (consider using --machine=<user>@.host --user to connect to bus of other user)" :
"Failed to connect to bus: %m");
}
int bus_async_unregister_and_exit(sd_event *e, sd_bus *bus, const char *name) {
const char *match;
const char *unique;
int r;
assert(e);
assert(bus);
assert(name);
/* We unregister the name here and then wait for the
* NameOwnerChanged signal for this event to arrive before we
* quit. We do this in order to make sure that any queued
* requests are still processed before we really exit. */
r = sd_bus_get_unique_name(bus, &unique);
if (r < 0)
return r;
match = strjoina(
"sender='org.freedesktop.DBus',"
"type='signal',"
"interface='org.freedesktop.DBus',"
"member='NameOwnerChanged',"
"path='/org/freedesktop/DBus',"
"arg0='", name, "',",
"arg1='", unique, "',",
"arg2=''");
r = sd_bus_add_match_async(bus, NULL, match, name_owner_change_callback, NULL, e);
if (r < 0)
return r;
r = sd_bus_release_name_async(bus, NULL, name, NULL, NULL);
if (r < 0)
return r;
return 0;
}
int bus_event_loop_with_idle(
sd_event *e,
sd_bus *bus,
const char *name,
usec_t timeout,
check_idle_t check_idle,
void *userdata) {
bool exiting = false;
int r, code;
assert(e);
assert(bus);
assert(name);
for (;;) {
bool idle;
r = sd_event_get_state(e);
if (r < 0)
return r;
if (r == SD_EVENT_FINISHED)
break;
if (check_idle)
idle = check_idle(userdata);
else
idle = true;
r = sd_event_run(e, exiting || !idle ? UINT64_MAX : timeout);
if (r < 0)
return r;
if (r == 0 && !exiting && idle) {
/* Inform the service manager that we are going down, so that it will queue all
* further start requests, instead of assuming we are already running. */
sd_notify(false, "STOPPING=1");
r = bus_async_unregister_and_exit(e, bus, name);
if (r < 0)
return r;
exiting = true;
continue;
}
}
r = sd_event_get_exit_code(e, &code);
if (r < 0)
return r;
return code;
}
int bus_name_has_owner(sd_bus *c, const char *name, sd_bus_error *error) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *rep = NULL;
int r, has_owner = 0;
assert(c);
assert(name);
r = sd_bus_call_method(c,
"org.freedesktop.DBus",
"/org/freedesktop/dbus",
"org.freedesktop.DBus",
"NameHasOwner",
error,
&rep,
"s",
name);
if (r < 0)
return r;
r = sd_bus_message_read_basic(rep, 'b', &has_owner);
if (r < 0)
return sd_bus_error_set_errno(error, r);
return has_owner;
}
bool bus_error_is_unknown_service(const sd_bus_error *error) {
return sd_bus_error_has_names(error,
SD_BUS_ERROR_SERVICE_UNKNOWN,
SD_BUS_ERROR_NAME_HAS_NO_OWNER,
BUS_ERROR_NO_SUCH_UNIT);
}
int bus_check_peercred(sd_bus *c) {
struct ucred ucred;
int fd, r;
assert(c);
fd = sd_bus_get_fd(c);
if (fd < 0)
return fd;
r = getpeercred(fd, &ucred);
if (r < 0)
return r;
if (ucred.uid != 0 && ucred.uid != geteuid())
return -EPERM;
return 1;
}
int bus_connect_system_systemd(sd_bus **_bus) {
_cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
int r;
assert(_bus);
if (geteuid() != 0)
return sd_bus_default_system(_bus);
/* If we are root then let's talk directly to the system
* instance, instead of going via the bus */
r = sd_bus_new(&bus);
if (r < 0)
return r;
r = sd_bus_set_address(bus, "unix:path=/run/systemd/private");
if (r < 0)
return r;
r = sd_bus_start(bus);
if (r < 0)
return sd_bus_default_system(_bus);
r = bus_check_peercred(bus);
if (r < 0)
return r;
*_bus = TAKE_PTR(bus);
return 0;
}
int bus_connect_user_systemd(sd_bus **_bus) {
_cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
_cleanup_free_ char *ee = NULL;
const char *e;
int r;
assert(_bus);
e = secure_getenv("XDG_RUNTIME_DIR");
if (!e)
return sd_bus_default_user(_bus);
ee = bus_address_escape(e);
if (!ee)
return -ENOMEM;
r = sd_bus_new(&bus);
if (r < 0)
return r;
bus->address = strjoin("unix:path=", ee, "/systemd/private");
if (!bus->address)
return -ENOMEM;
r = sd_bus_start(bus);
if (r < 0)
return sd_bus_default_user(_bus);
r = bus_check_peercred(bus);
if (r < 0)
return r;
*_bus = TAKE_PTR(bus);
return 0;
}
int bus_connect_transport(
BusTransport transport,
const char *host,
bool user,
sd_bus **ret) {
_cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
int r;
assert(transport >= 0);
assert(transport < _BUS_TRANSPORT_MAX);
assert(ret);
assert_return((transport == BUS_TRANSPORT_LOCAL) == !host, -EINVAL);
assert_return(transport != BUS_TRANSPORT_REMOTE || !user, -EOPNOTSUPP);
switch (transport) {
case BUS_TRANSPORT_LOCAL:
if (user)
r = sd_bus_default_user(&bus);
else {
if (sd_booted() <= 0)
/* Print a friendly message when the local system is actually not running systemd as PID 1. */
return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
"System has not been booted with systemd as init system (PID 1). Can't operate.");
r = sd_bus_default_system(&bus);
}
break;
case BUS_TRANSPORT_REMOTE:
r = sd_bus_open_system_remote(&bus, host);
break;
case BUS_TRANSPORT_MACHINE:
if (user)
r = sd_bus_open_user_machine(&bus, host);
else
r = sd_bus_open_system_machine(&bus, host);
break;
default:
assert_not_reached();
}
if (r < 0)
return r;
r = sd_bus_set_exit_on_disconnect(bus, true);
if (r < 0)
return r;
*ret = TAKE_PTR(bus);
return 0;
}
int bus_connect_transport_systemd(BusTransport transport, const char *host, bool user, sd_bus **bus) {
int r;
assert(transport >= 0);
assert(transport < _BUS_TRANSPORT_MAX);
assert(bus);
assert_return((transport == BUS_TRANSPORT_LOCAL) == !host, -EINVAL);
assert_return(transport == BUS_TRANSPORT_LOCAL || !user, -EOPNOTSUPP);
switch (transport) {
case BUS_TRANSPORT_LOCAL:
if (user)
r = bus_connect_user_systemd(bus);
else {
if (sd_booted() <= 0)
/* Print a friendly message when the local system is actually not running systemd as PID 1. */
return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
"System has not been booted with systemd as init system (PID 1). Can't operate.");
r = bus_connect_system_systemd(bus);
}
break;
case BUS_TRANSPORT_REMOTE:
r = sd_bus_open_system_remote(bus, host);
break;
case BUS_TRANSPORT_MACHINE:
r = sd_bus_open_system_machine(bus, host);
break;
default:
assert_not_reached();
}
return r;
}
/**
* bus_path_encode_unique() - encode unique object path
* @b: bus connection or NULL
* @prefix: object path prefix
* @sender_id: unique-name of client, or NULL
* @external_id: external ID to be chosen by client, or NULL
* @ret_path: storage for encoded object path pointer
*
* Whenever we provide a bus API that allows clients to create and manage
* server-side objects, we need to provide a unique name for these objects. If
* we let the server choose the name, we suffer from a race condition: If a
* client creates an object asynchronously, it cannot destroy that object until
* it received the method reply. It cannot know the name of the new object,
* thus, it cannot destroy it. Furthermore, it enforces a round-trip.
*
* Therefore, many APIs allow the client to choose the unique name for newly
* created objects. There're two problems to solve, though:
* 1) Object names are usually defined via dbus object paths, which are
* usually globally namespaced. Therefore, multiple clients must be able
* to choose unique object names without interference.
* 2) If multiple libraries share the same bus connection, they must be
* able to choose unique object names without interference.
* The first problem is solved easily by prefixing a name with the
* unique-bus-name of a connection. The server side must enforce this and
* reject any other name. The second problem is solved by providing unique
* suffixes from within sd-bus.
*
* This helper allows clients to create unique object-paths. It uses the
* template '/prefix/sender_id/external_id' and returns the new path in
* @ret_path (must be freed by the caller).
* If @sender_id is NULL, the unique-name of @b is used. If @external_id is
* NULL, this function allocates a unique suffix via @b (by requesting a new
* cookie). If both @sender_id and @external_id are given, @b can be passed as
* NULL.
*
* Returns: 0 on success, negative error code on failure.
*/
int bus_path_encode_unique(sd_bus *b, const char *prefix, const char *sender_id, const char *external_id, char **ret_path) {
_cleanup_free_ char *sender_label = NULL, *external_label = NULL;
char external_buf[DECIMAL_STR_MAX(uint64_t)], *p;
int r;
assert_return(b || (sender_id && external_id), -EINVAL);
assert_return(sd_bus_object_path_is_valid(prefix), -EINVAL);
assert_return(ret_path, -EINVAL);
if (!sender_id) {
r = sd_bus_get_unique_name(b, &sender_id);
if (r < 0)
return r;
}
if (!external_id) {
xsprintf(external_buf, "%"PRIu64, ++b->cookie);
external_id = external_buf;
}
sender_label = bus_label_escape(sender_id);
if (!sender_label)
return -ENOMEM;
external_label = bus_label_escape(external_id);
if (!external_label)
return -ENOMEM;
p = path_join(prefix, sender_label, external_label);
if (!p)
return -ENOMEM;
*ret_path = p;
return 0;
}
/**
* bus_path_decode_unique() - decode unique object path
* @path: object path to decode
* @prefix: object path prefix
* @ret_sender: output parameter for sender-id label
* @ret_external: output parameter for external-id label
*
* This does the reverse of bus_path_encode_unique() (see its description for
* details). Both trailing labels, sender-id and external-id, are unescaped and
* returned in the given output parameters (the caller must free them).
*
* Note that this function returns 0 if the path does not match the template
* (see bus_path_encode_unique()), 1 if it matched.
*
* Returns: Negative error code on failure, 0 if the given object path does not
* match the template (return parameters are set to NULL), 1 if it was
* parsed successfully (return parameters contain allocated labels).
*/
int bus_path_decode_unique(const char *path, const char *prefix, char **ret_sender, char **ret_external) {
const char *p, *q;
char *sender, *external;
assert(sd_bus_object_path_is_valid(path));
assert(sd_bus_object_path_is_valid(prefix));
assert(ret_sender);
assert(ret_external);
p = object_path_startswith(path, prefix);
if (!p) {
*ret_sender = NULL;
*ret_external = NULL;
return 0;
}
q = strchr(p, '/');
if (!q) {
*ret_sender = NULL;
*ret_external = NULL;
return 0;
}
sender = bus_label_unescape_n(p, q - p);
external = bus_label_unescape(q + 1);
if (!sender || !external) {
free(sender);
free(external);
return -ENOMEM;
}
*ret_sender = sender;
*ret_external = external;
return 1;
}
int bus_track_add_name_many(sd_bus_track *t, char **l) {
int r = 0;
assert(t);
/* Continues adding after failure, and returns the first failure. */
STRV_FOREACH(i, l) {
int k;
k = sd_bus_track_add_name(t, *i);
if (k < 0 && r >= 0)
r = k;
}
return r;
}
int bus_open_system_watch_bind_with_description(sd_bus **ret, const char *description) {
_cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
const char *e;
int r;
assert(ret);
/* Match like sd_bus_open_system(), but with the "watch_bind" feature and the Connected() signal
* turned on. */
r = sd_bus_new(&bus);
if (r < 0)
return r;
if (description) {
r = sd_bus_set_description(bus, description);
if (r < 0)
return r;
}
e = secure_getenv("DBUS_SYSTEM_BUS_ADDRESS");
if (!e)
e = DEFAULT_SYSTEM_BUS_ADDRESS;
r = sd_bus_set_address(bus, e);
if (r < 0)
return r;
r = sd_bus_set_bus_client(bus, true);
if (r < 0)
return r;
r = sd_bus_negotiate_creds(bus, true, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID|SD_BUS_CREDS_EFFECTIVE_CAPS);
if (r < 0)
return r;
r = sd_bus_set_watch_bind(bus, true);
if (r < 0)
return r;
r = sd_bus_set_connected_signal(bus, true);
if (r < 0)
return r;
r = sd_bus_start(bus);
if (r < 0)
return r;
*ret = TAKE_PTR(bus);
return 0;
}
int bus_reply_pair_array(sd_bus_message *m, char **l) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
int r;
assert(m);
/* Reply to the specified message with a message containing a dictionary put together from the
* specified strv */
r = sd_bus_message_new_method_return(m, &reply);
if (r < 0)
return r;
r = sd_bus_message_open_container(reply, 'a', "{ss}");
if (r < 0)
return r;
STRV_FOREACH_PAIR(k, v, l) {
r = sd_bus_message_append(reply, "{ss}", *k, *v);
if (r < 0)
return r;
}
r = sd_bus_message_close_container(reply);
if (r < 0)
return r;
return sd_bus_send(NULL, reply, NULL);
}
static void bus_message_unref_wrapper(void *m) {
sd_bus_message_unref(m);
}
const struct hash_ops bus_message_hash_ops = {
.hash = trivial_hash_func,
.compare = trivial_compare_func,
.free_value = bus_message_unref_wrapper,
};