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Systemd/src/bus-proxyd/bus-proxyd.c

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 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 <http://www.gnu.org/licenses/>.
***/
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/poll.h>
#include <stddef.h>
#include <getopt.h>
#include "log.h"
#include "util.h"
#include "socket-util.h"
#include "sd-daemon.h"
#include "sd-bus.h"
#include "bus-internal.h"
#include "bus-message.h"
#include "bus-util.h"
#include "build.h"
#include "strv.h"
#include "def.h"
static const char *arg_address = DEFAULT_SYSTEM_BUS_PATH;
static char *arg_command_line_buffer = NULL;
static int help(void) {
printf("%s [OPTIONS...]\n\n"
"Connect STDIO or a socket to a given bus address.\n\n"
" -h --help Show this help\n"
" --version Show package version\n"
" --address=ADDRESS Connect to the bus specified by ADDRESS\n"
" (default: " DEFAULT_SYSTEM_BUS_PATH ")\n",
program_invocation_short_name);
return 0;
}
static int parse_argv(int argc, char *argv[]) {
enum {
ARG_VERSION = 0x100,
ARG_ADDRESS,
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, ARG_VERSION },
{ "address", required_argument, NULL, ARG_ADDRESS },
{ NULL, 0, NULL, 0 }
};
int c;
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
switch (c) {
case 'h':
help();
return 0;
case ARG_VERSION:
puts(PACKAGE_STRING);
puts(SYSTEMD_FEATURES);
return 0;
case ARG_ADDRESS:
arg_address = optarg;
break;
case '?':
return -EINVAL;
default:
assert_not_reached("Unhandled option");
}
}
/* If the first command line argument is only "x" characters
* we'll write who we are talking to into it, so that "ps" is
* explanatory */
arg_command_line_buffer = argv[optind];
if (argc > optind + 1 ||
(arg_command_line_buffer && arg_command_line_buffer[strspn(arg_command_line_buffer, "x")] != 0)) {
log_error("Too many arguments");
return -EINVAL;
}
return 1;
}
static int rename_service(sd_bus *a, sd_bus *b) {
_cleanup_bus_creds_unref_ sd_bus_creds *creds = NULL;
_cleanup_free_ char *p = NULL, *name = NULL;
const char *comm;
char **cmdline;
uid_t uid;
pid_t pid;
int r;
assert(a);
assert(b);
r = sd_bus_get_peer_creds(b, SD_BUS_CREDS_UID|SD_BUS_CREDS_PID|SD_BUS_CREDS_CMDLINE|SD_BUS_CREDS_COMM, &creds);
if (r < 0)
return r;
r = sd_bus_creds_get_uid(creds, &uid);
if (r < 0)
return r;
r = sd_bus_creds_get_pid(creds, &pid);
if (r < 0)
return r;
r = sd_bus_creds_get_cmdline(creds, &cmdline);
if (r < 0)
return r;
r = sd_bus_creds_get_comm(creds, &comm);
if (r < 0)
return r;
name = uid_to_name(uid);
if (!name)
return -ENOMEM;
p = strv_join(cmdline, " ");
if (!p)
return -ENOMEM;
/* The status string gets the full command line ... */
sd_notifyf(false,
"STATUS=Processing requests from client PID "PID_FMT" (%s); UID "UID_FMT" (%s)",
pid, p,
uid, name);
/* ... and the argv line only the short comm */
if (arg_command_line_buffer) {
size_t m, w;
m = strlen(arg_command_line_buffer);
w = snprintf(arg_command_line_buffer, m,
"[PID "PID_FMT"/%s; UID "UID_FMT"/%s]",
pid, comm,
uid, name);
if (m > w)
memzero(arg_command_line_buffer + w, m - w);
}
log_debug("Running on behalf of PID "PID_FMT" (%s), UID "UID_FMT" (%s), %s",
pid, p,
uid, name,
a->unique_name);
;
return 0;
}
static int synthesize_name_acquired(sd_bus *a, sd_bus *b, sd_bus_message *m) {
_cleanup_bus_message_unref_ sd_bus_message *n = NULL;
const char *name, *old_owner, *new_owner;
int r;
assert(a);
assert(b);
assert(m);
/* If we get NameOwnerChanged for our own name, we need to
* synthesize NameLost/NameAcquired, since socket clients need
* that, even though it is obsoleted on kdbus */
if (!a->is_kernel)
return 0;
if (!sd_bus_message_is_signal(m, "org.freedesktop.DBus", "NameOwnerChanged") ||
!streq_ptr(m->path, "/org/freedesktop/DBus") ||
!streq_ptr(m->sender, "org.freedesktop.DBus"))
return 0;
r = sd_bus_message_read(m, "sss", &name, &old_owner, &new_owner);
if (r < 0)
return r;
r = sd_bus_message_rewind(m, true);
if (r < 0)
return r;
if (streq(old_owner, a->unique_name)) {
r = sd_bus_message_new_signal(
b,
"/org/freedesktop/DBus",
"org.freedesktop.DBus",
"NameLost",
&n);
} else if (streq(new_owner, a->unique_name)) {
r = sd_bus_message_new_signal(
b,
"/org/freedesktop/DBus",
"org.freedesktop.DBus",
"NameAcquired",
&n);
} else
return 0;
if (r < 0)
return r;
r = sd_bus_message_append(n, "s", name);
if (r < 0)
return r;
r = bus_message_append_sender(n, "org.freedesktop.DBus");
if (r < 0)
return r;
r = bus_seal_synthetic_message(b, n);
if (r < 0)
return r;
return sd_bus_send(b, n, NULL);
}
static int process_policy(sd_bus *a, sd_bus *b, sd_bus_message *m) {
_cleanup_bus_message_unref_ sd_bus_message *n = NULL;
int r;
assert(a);
assert(b);
assert(m);
if (!sd_bus_message_is_method_call(m, "org.freedesktop.DBus.Properties", "GetAll"))
return 0;
if (!streq_ptr(m->path, "/org/gnome/DisplayManager/Slave"))
return 0;
r = sd_bus_message_new_method_errorf(m, &n, SD_BUS_ERROR_ACCESS_DENIED, "gdm, you are stupid");
if (r < 0)
return r;
r = bus_message_append_sender(n, "org.freedesktop.DBus");
if (r < 0) {
log_error("Failed to append sender to gdm reply: %s", strerror(-r));
return r;
}
r = bus_seal_synthetic_message(b, n);
if (r < 0) {
log_error("Failed to seal gdm reply: %s", strerror(-r));
return r;
}
r = sd_bus_send(b, n, NULL);
if (r < 0) {
log_error("Failed to send gdm reply: %s", strerror(-r));
return r;
}
return 1;
}
static int process_hello(sd_bus *a, sd_bus *b, sd_bus_message *m, bool *got_hello) {
_cleanup_bus_message_unref_ sd_bus_message *n = NULL;
bool is_hello;
int r;
assert(a);
assert(b);
assert(m);
assert(got_hello);
/* As reaction to hello we need to respond with two messages:
* the callback reply and the NameAcquired for the unique
* name, since hello is otherwise obsolete on kdbus. */
is_hello =
sd_bus_message_is_method_call(m, "org.freedesktop.DBus", "Hello") &&
streq_ptr(m->destination, "org.freedesktop.DBus");
if (!is_hello) {
if (*got_hello)
return 0;
log_error("First packet isn't hello (it's %s.%s), aborting.", m->interface, m->member);
return -EIO;
}
if (*got_hello) {
log_error("Got duplicate hello, aborting.");
return -EIO;
}
*got_hello = true;
if (!a->is_kernel)
return 0;
r = sd_bus_message_new_method_return(m, &n);
if (r < 0) {
log_error("Failed to generate HELLO reply: %s", strerror(-r));
return r;
}
r = sd_bus_message_append(n, "s", a->unique_name);
if (r < 0) {
log_error("Failed to append unique name to HELLO reply: %s", strerror(-r));
return r;
}
r = bus_message_append_sender(n, "org.freedesktop.DBus");
if (r < 0) {
log_error("Failed to append sender to HELLO reply: %s", strerror(-r));
return r;
}
r = bus_seal_synthetic_message(b, n);
if (r < 0) {
log_error("Failed to seal HELLO reply: %s", strerror(-r));
return r;
}
r = sd_bus_send(b, n, NULL);
if (r < 0) {
log_error("Failed to send HELLO reply: %s", strerror(-r));
return r;
}
n = sd_bus_message_unref(n);
r = sd_bus_message_new_signal(
b,
"/org/freedesktop/DBus",
"org.freedesktop.DBus",
"NameAcquired",
&n);
if (r < 0) {
log_error("Failed to allocate initial NameAcquired message: %s", strerror(-r));
return r;
}
r = sd_bus_message_append(n, "s", a->unique_name);
if (r < 0) {
log_error("Failed to append unique name to NameAcquired message: %s", strerror(-r));
return r;
}
r = bus_message_append_sender(n, "org.freedesktop.DBus");
if (r < 0) {
log_error("Failed to append sender to NameAcquired message: %s", strerror(-r));
return r;
}
r = bus_seal_synthetic_message(b, n);
if (r < 0) {
log_error("Failed to seal NameAcquired message: %s", strerror(-r));
return r;
}
r = sd_bus_send(b, n, NULL);
if (r < 0) {
log_error("Failed to send NameAcquired message: %s", strerror(-r));
return r;
}
return 1;
}
static int patch_sender(sd_bus *a, sd_bus_message *m) {
char **well_known = NULL;
sd_bus_creds *c;
int r;
assert(a);
assert(m);
if (!a->is_kernel)
return 0;
/* We will change the sender of messages from the bus driver
* so that they originate from the bus driver. This is a
* speciality originating from dbus1, where the bus driver did
* not have a unique id, but only the well-known name. */
c = sd_bus_message_get_creds(m);
if (!c)
return 0;
r = sd_bus_creds_get_well_known_names(c, &well_known);
if (r < 0)
return r;
if (strv_contains(well_known, "org.freedesktop.DBus"))
m->sender = "org.freedesktop.DBus";
return 0;
}
int main(int argc, char *argv[]) {
_cleanup_bus_unref_ sd_bus *a = NULL, *b = NULL;
sd_id128_t server_id;
int r, in_fd, out_fd;
bool got_hello = false;
bool is_unix;
struct ucred ucred = {};
_cleanup_free_ char *peersec = NULL;
log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
log_parse_environment();
log_open();
r = parse_argv(argc, argv);
if (r <= 0)
goto finish;
r = sd_listen_fds(0);
if (r == 0) {
in_fd = STDIN_FILENO;
out_fd = STDOUT_FILENO;
} else if (r == 1) {
in_fd = SD_LISTEN_FDS_START;
out_fd = SD_LISTEN_FDS_START;
} else {
log_error("Illegal number of file descriptors passed");
goto finish;
}
is_unix =
sd_is_socket(in_fd, AF_UNIX, 0, 0) > 0 &&
sd_is_socket(out_fd, AF_UNIX, 0, 0) > 0;
if (is_unix) {
getpeercred(in_fd, &ucred);
getpeersec(in_fd, &peersec);
}
r = sd_bus_new(&a);
if (r < 0) {
log_error("Failed to allocate bus: %s", strerror(-r));
goto finish;
}
r = sd_bus_set_name(a, "sd-proxy");
if (r < 0) {
log_error("Failed to set bus name: %s", strerror(-r));
goto finish;
}
r = sd_bus_set_address(a, arg_address);
if (r < 0) {
log_error("Failed to set address to connect to: %s", strerror(-r));
goto finish;
}
r = sd_bus_negotiate_fds(a, is_unix);
if (r < 0) {
log_error("Failed to set FD negotiation: %s", strerror(-r));
goto finish;
}
if (ucred.pid > 0) {
a->fake_creds.pid = ucred.pid;
a->fake_creds.uid = ucred.uid;
a->fake_creds.gid = ucred.gid;
a->fake_creds_valid = true;
}
if (peersec) {
a->fake_label = peersec;
peersec = NULL;
}
a->manual_peer_interface = true;
r = sd_bus_start(a);
if (r < 0) {
log_error("Failed to start bus client: %s", strerror(-r));
goto finish;
}
r = sd_bus_get_server_id(a, &server_id);
if (r < 0) {
log_error("Failed to get server ID: %s", strerror(-r));
goto finish;
}
r = sd_bus_new(&b);
if (r < 0) {
log_error("Failed to allocate bus: %s", strerror(-r));
goto finish;
}
r = sd_bus_set_fd(b, in_fd, out_fd);
if (r < 0) {
log_error("Failed to set fds: %s", strerror(-r));
goto finish;
}
r = sd_bus_set_server(b, 1, server_id);
if (r < 0) {
log_error("Failed to set server mode: %s", strerror(-r));
goto finish;
}
r = sd_bus_negotiate_fds(b, is_unix);
if (r < 0) {
log_error("Failed to set FD negotiation: %s", strerror(-r));
goto finish;
}
r = sd_bus_set_anonymous(b, true);
if (r < 0) {
log_error("Failed to set anonymous authentication: %s", strerror(-r));
goto finish;
}
b->manual_peer_interface = true;
r = sd_bus_start(b);
if (r < 0) {
log_error("Failed to start bus client: %s", strerror(-r));
goto finish;
}
r = rename_service(a, b);
if (r < 0)
log_debug("Failed to rename process: %s", strerror(-r));
if (a->is_kernel) {
_cleanup_free_ char *match = NULL;
const char *unique;
r = sd_bus_get_unique_name(a, &unique);
if (r < 0) {
log_error("Failed to get unique name: %s", strerror(-r));
goto finish;
}
match = strjoin("type='signal',"
"sender='org.freedesktop.DBus',"
"path='/org/freedesktop/DBus',"
"interface='org.freedesktop.DBus',"
"member='NameOwnerChanged',"
"arg1='",
unique,
"'",
NULL);
if (!match) {
log_oom();
goto finish;
}
r = sd_bus_add_match(a, match, NULL, NULL);
if (r < 0) {
log_error("Failed to add match for NameLost: %s", strerror(-r));
goto finish;
}
free(match);
match = strjoin("type='signal',"
"sender='org.freedesktop.DBus',"
"path='/org/freedesktop/DBus',"
"interface='org.freedesktop.DBus',"
"member='NameOwnerChanged',"
"arg2='",
unique,
"'",
NULL);
if (!match) {
log_oom();
goto finish;
}
r = sd_bus_add_match(a, match, NULL, NULL);
if (r < 0) {
log_error("Failed to add match for NameAcquired: %s", strerror(-r));
goto finish;
}
}
for (;;) {
_cleanup_bus_message_unref_ sd_bus_message *m = NULL;
int events_a, events_b, fd;
uint64_t timeout_a, timeout_b, t;
struct timespec _ts, *ts;
struct pollfd *pollfd;
int k;
if (got_hello) {
r = sd_bus_process(a, &m);
if (r < 0) {
/* treat 'connection reset by peer' as clean exit condition */
if (r == -ECONNRESET)
r = 0;
else
log_error("Failed to process bus a: %s", strerror(-r));
goto finish;
}
if (m) {
/* We officially got EOF, let's quit */
if (sd_bus_message_is_signal(m, "org.freedesktop.DBus.Local", "Disconnected")) {
r = 0;
goto finish;
}
k = synthesize_name_acquired(a, b, m);
if (k < 0) {
r = k;
log_error("Failed to synthesize message: %s", strerror(-r));
goto finish;
}
patch_sender(a, m);
k = sd_bus_send(b, m, NULL);
if (k < 0) {
if (k == -ECONNRESET)
r = 0;
else {
r = k;
log_error("Failed to send message: %s", strerror(-r));
}
goto finish;
}
}
if (r > 0)
continue;
}
r = sd_bus_process(b, &m);
if (r < 0) {
/* treat 'connection reset by peer' as clean exit condition */
if (r == -ECONNRESET)
r = 0;
else
log_error("Failed to process bus b: %s", strerror(-r));
goto finish;
}
if (m) {
/* We officially got EOF, let's quit */
if (sd_bus_message_is_signal(m, "org.freedesktop.DBus.Local", "Disconnected")) {
r = 0;
goto finish;
}
k = process_hello(a, b, m, &got_hello);
if (k < 0) {
r = k;
log_error("Failed to process HELLO: %s", strerror(-r));
goto finish;
}
if (k > 0)
r = k;
else {
k = process_policy(a, b, m);
if (k < 0) {
r = k;
log_error("Failed to process policy: %s", strerror(-r));
goto finish;
}
k = sd_bus_send(a, m, NULL);
if (k < 0) {
if (r == -ECONNRESET)
r = 0;
else {
r = k;
log_error("Failed to send message: %s", strerror(-r));
}
goto finish;
}
}
}
if (r > 0)
continue;
fd = sd_bus_get_fd(a);
if (fd < 0) {
log_error("Failed to get fd: %s", strerror(-r));
goto finish;
}
events_a = sd_bus_get_events(a);
if (events_a < 0) {
log_error("Failed to get events mask: %s", strerror(-r));
goto finish;
}
r = sd_bus_get_timeout(a, &timeout_a);
if (r < 0) {
log_error("Failed to get timeout: %s", strerror(-r));
goto finish;
}
events_b = sd_bus_get_events(b);
if (events_b < 0) {
log_error("Failed to get events mask: %s", strerror(-r));
goto finish;
}
r = sd_bus_get_timeout(b, &timeout_b);
if (r < 0) {
log_error("Failed to get timeout: %s", strerror(-r));
goto finish;
}
t = timeout_a;
if (t == (uint64_t) -1 || (timeout_b != (uint64_t) -1 && timeout_b < timeout_a))
t = timeout_b;
if (t == (uint64_t) -1)
ts = NULL;
else {
usec_t nw;
nw = now(CLOCK_MONOTONIC);
if (t > nw)
t -= nw;
else
t = 0;
ts = timespec_store(&_ts, t);
}
pollfd = (struct pollfd[3]) {
{.fd = fd, .events = events_a, },
{.fd = in_fd, .events = events_b & POLLIN, },
{.fd = out_fd, .events = events_b & POLLOUT, }
};
r = ppoll(pollfd, 3, ts, NULL);
if (r < 0) {
log_error("ppoll() failed: %m");
goto finish;
}
}
r = 0;
finish:
sd_bus_flush(a);
sd_bus_flush(b);
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}
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