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Systemd/src/machine/machined-dbus.c
Lennart Poettering adacb9575a bus: introduce "trusted" bus concept and encode access control in object vtables 
Introduces a new concept of "trusted" vs. "untrusted" busses. For the
latter libsystemd-bus will automatically do per-method access control,
for the former all access is automatically granted. Per-method access
control is encoded in the vtables: by default all methods are only
accessible to privileged clients. If the SD_BUS_VTABLE_UNPRIVILEGED flag
is set for a method it is accessible to unprivileged clients too. By
default whether a client is privileged is determined via checking for
its CAP_SYS_ADMIN capability, but this can be altered via the
SD_BUS_VTABLE_CAPABILITY() macro that can be ORed into the flags field
of the method.

Writable properties are also subject to SD_BUS_VTABLE_UNPRIVILEGED and
SD_BUS_VTABLE_CAPABILITY() for controlling write access to them. Note
however that read access is unrestricted, as PropertiesChanged messages
might send out the values anyway as an unrestricted broadcast.

By default the system bus is set to "untrusted" and the user bus is
"trusted" since per-method access control on the latter is unnecessary.

On dbus1 busses we check the UID of the caller rather than the
configured capability since the capability cannot be determined without
race. On kdbus the capability is checked if possible from the attached
meta-data of a message and otherwise queried from the sending peer.

This also decorates the vtables of the various daemons we ship with
these flags.
2013-12-10 16:52:49 +00:00

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2011 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 <errno.h>
#include <string.h>
#include <unistd.h>
#include <pwd.h>
#include <sys/capability.h>
#include "sd-id128.h"
#include "sd-messages.h"
#include "strv.h"
#include "mkdir.h"
#include "path-util.h"
#include "special.h"
#include "fileio-label.h"
#include "label.h"
#include "utf8.h"
#include "unit-name.h"
#include "bus-util.h"
#include "bus-errors.h"
#include "time-util.h"
#include "cgroup-util.h"
#include "machined.h"
static bool valid_machine_name(const char *p) {
size_t l;
if (!filename_is_safe(p))
return false;
if (!ascii_is_valid(p))
return false;
l = strlen(p);
if (l < 1 || l> 64)
return false;
return true;
}
static int method_get_machine(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_free_ char *p = NULL;
Manager *m = userdata;
Machine *machine;
const char *name;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_read(message, "s", &name);
if (r < 0)
return r;
machine = hashmap_get(m->machines, name);
if (!machine)
return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_MACHINE, "No machine '%s' known", name);
p = machine_bus_path(machine);
if (!p)
return -ENOMEM;
return sd_bus_reply_method_return(message, "o", p);
}
static int method_get_machine_by_pid(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_free_ char *p = NULL;
Manager *m = userdata;
Machine *machine = NULL;
pid_t pid;
int r;
assert(bus);
assert(message);
assert(m);
assert_cc(sizeof(pid_t) == sizeof(uint32_t));
r = sd_bus_message_read(message, "u", &pid);
if (r < 0)
return r;
if (pid == 0) {
_cleanup_bus_creds_unref_ sd_bus_creds *creds = NULL;
r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_PID, &creds);
if (r < 0)
return r;
r = sd_bus_creds_get_pid(creds, &pid);
if (r < 0)
return r;
}
r = manager_get_machine_by_pid(m, pid, &machine);
if (r < 0)
return r;
if (!machine)
return sd_bus_error_setf(error, BUS_ERROR_NO_MACHINE_FOR_PID, "PID %lu does not belong to any known machine", (unsigned long) pid);
p = machine_bus_path(machine);
if (!p)
return -ENOMEM;
return sd_bus_reply_method_return(message, "o", p);
}
static int method_list_machines(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
Manager *m = userdata;
Machine *machine;
Iterator i;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_new_method_return(message, &reply);
if (r < 0)
return sd_bus_error_set_errno(error, r);
r = sd_bus_message_open_container(reply, 'a', "(ssso)");
if (r < 0)
return sd_bus_error_set_errno(error, r);
HASHMAP_FOREACH(machine, m->machines, i) {
_cleanup_free_ char *p = NULL;
p = machine_bus_path(machine);
if (!p)
return -ENOMEM;
r = sd_bus_message_append(reply, "(ssso)",
machine->name,
strempty(machine_class_to_string(machine->class)),
machine->service,
p);
if (r < 0)
return sd_bus_error_set_errno(error, r);
}
r = sd_bus_message_close_container(reply);
if (r < 0)
return sd_bus_error_set_errno(error, r);
return sd_bus_send(bus, reply, NULL);
}
static int method_create_machine(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
const char *name, *service, *class, *root_directory;
Manager *manager = userdata;
MachineClass c;
uint32_t leader;
sd_id128_t id;
const void *v;
Machine *m;
size_t n;
int r;
assert(bus);
assert(message);
assert(manager);
r = sd_bus_message_read(message, "s", &name);
if (r < 0)
return r;
if (!valid_machine_name(name))
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid machine name");
r = sd_bus_message_read_array(message, 'y', &v, &n);
if (r < 0)
return r;
if (n == 0)
id = SD_ID128_NULL;
else if (n == 16)
memcpy(&id, v, n);
else
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid machine ID parameter");
r = sd_bus_message_read(message, "ssus", &service, &class, &leader, &root_directory);
if (r < 0)
return r;
if (isempty(class))
c = _MACHINE_CLASS_INVALID;
else {
c = machine_class_from_string(class);
if (c < 0)
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid machine class parameter");
}
if (leader == 1)
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid leader PID");
if (!isempty(root_directory) && !path_is_absolute(root_directory))
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Root directory must be empty or an absolute path");
r = sd_bus_message_enter_container(message, 'a', "(sv)");
if (r < 0)
return r;
if (leader == 0) {
_cleanup_bus_creds_unref_ sd_bus_creds *creds = NULL;
r = sd_bus_query_sender_creds(message, SD_BUS_CREDS_PID, &creds);
if (r < 0)
return r;
assert_cc(sizeof(uint32_t) == sizeof(pid_t));
r = sd_bus_creds_get_pid(creds, (pid_t*) &leader);
if (r < 0)
return r;
}
if (hashmap_get(manager->machines, name))
return sd_bus_error_setf(error, BUS_ERROR_MACHINE_EXISTS, "Machine '%s' already exists", name);
r = manager_add_machine(manager, name, &m);
if (r < 0)
return r;
m->leader = leader;
m->class = c;
m->id = id;
if (!isempty(service)) {
m->service = strdup(service);
if (!m->service) {
r = -ENOMEM;
goto fail;
}
}
if (!isempty(root_directory)) {
m->root_directory = strdup(root_directory);
if (!m->root_directory) {
r = -ENOMEM;
goto fail;
}
}
r = machine_start(m, message, error);
if (r < 0)
goto fail;
m->create_message = sd_bus_message_ref(message);
return 1;
fail:
machine_add_to_gc_queue(m);
return r;
}
static int method_terminate_machine(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
Manager *m = userdata;
Machine *machine;
const char *name;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_read(message, "s", &name);
if (r < 0)
return sd_bus_error_set_errno(error, r);
machine = hashmap_get(m->machines, name);
if (!machine)
return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_MACHINE, "No machine '%s' known", name);
r = machine_stop(machine);
if (r < 0)
return sd_bus_error_set_errno(error, r);
return sd_bus_reply_method_return(message, NULL);
}
static int method_kill_machine(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
Manager *m = userdata;
Machine *machine;
const char *name;
const char *swho;
int32_t signo;
KillWho who;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_read(message, "ssi", &name, &swho, &signo);
if (r < 0)
return sd_bus_error_set_errno(error, r);
if (isempty(swho))
who = KILL_ALL;
else {
who = kill_who_from_string(swho);
if (who < 0)
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid kill parameter '%s'", swho);
}
if (signo <= 0 || signo >= _NSIG)
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid signal %i", signo);
machine = hashmap_get(m->machines, name);
if (!machine)
return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_MACHINE, "No machine '%s' known", name);
r = machine_kill(machine, who, signo);
if (r < 0)
return sd_bus_error_set_errno(error, r);
return sd_bus_reply_method_return(message, NULL);
}
const sd_bus_vtable manager_vtable[] = {
SD_BUS_VTABLE_START(0),
SD_BUS_METHOD("GetMachine", "s", "o", method_get_machine, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("GetMachineByPID", "u", "o", method_get_machine_by_pid, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("ListMachines", NULL, "a(ssso)", method_list_machines, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("CreateMachine", "sayssusa(sv)", "o", method_create_machine, 0),
SD_BUS_METHOD("KillMachine", "ssi", NULL, method_kill_machine, SD_BUS_VTABLE_CAPABILITY(CAP_KILL)),
SD_BUS_METHOD("TerminateMachine", "s", NULL, method_terminate_machine, SD_BUS_VTABLE_CAPABILITY(CAP_KILL)),
SD_BUS_SIGNAL("MachineNew", "so", 0),
SD_BUS_SIGNAL("MachineRemoved", "so", 0),
SD_BUS_VTABLE_END
};
int match_job_removed(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
const char *path, *result, *unit;
Manager *m = userdata;
Machine *machine;
uint32_t id;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_read(message, "uoss", &id, &path, &unit, &result);
if (r < 0) {
bus_log_parse_error(r);
return r;
}
machine = hashmap_get(m->machine_units, unit);
if (!machine)
return 0;
if (streq_ptr(path, machine->scope_job)) {
free(machine->scope_job);
machine->scope_job = NULL;
if (machine->started) {
if (streq(result, "done"))
machine_send_create_reply(machine, NULL);
else {
_cleanup_bus_error_free_ sd_bus_error e = SD_BUS_ERROR_NULL;
sd_bus_error_setf(&e, BUS_ERROR_JOB_FAILED, "Start job for unit %s failed with '%s'", unit, result);
machine_send_create_reply(machine, &e);
}
} else
machine_save(machine);
}
machine_add_to_gc_queue(machine);
return 0;
}
int match_properties_changed(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_free_ char *unit = NULL;
Manager *m = userdata;
Machine *machine;
const char *path;
int r;
assert(bus);
assert(message);
assert(m);
path = sd_bus_message_get_path(message);
if (!path)
return 0;
r = unit_name_from_dbus_path(path, &unit);
if (r < 0)
return r;
machine = hashmap_get(m->machine_units, unit);
if (machine)
machine_add_to_gc_queue(machine);
return 0;
}
int match_unit_removed(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
const char *path, *unit;
Manager *m = userdata;
Machine *machine;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_read(message, "so", &unit, &path);
if (r < 0) {
bus_log_parse_error(r);
return r;
}
machine = hashmap_get(m->machine_units, unit);
if (machine)
machine_add_to_gc_queue(machine);
return 0;
}
int match_reloading(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
Manager *m = userdata;
Machine *machine;
Iterator i;
int b, r;
assert(bus);
r = sd_bus_message_read(message, "b", &b);
if (r < 0) {
bus_log_parse_error(r);
return r;
}
if (b)
return 0;
/* systemd finished reloading, let's recheck all our machines */
log_debug("System manager has been reloaded, rechecking machines...");
HASHMAP_FOREACH(machine, m->machines, i)
machine_add_to_gc_queue(machine);
return 0;
}
int manager_start_scope(
Manager *manager,
const char *scope,
pid_t pid,
const char *slice,
const char *description,
sd_bus_message *more_properties,
sd_bus_error *error,
char **job) {
_cleanup_bus_message_unref_ sd_bus_message *m = NULL, *reply = NULL;
int r;
assert(manager);
assert(scope);
assert(pid > 1);
r = sd_bus_message_new_method_call(
manager->bus,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
"org.freedesktop.systemd1.Manager",
"StartTransientUnit",
&m);
if (r < 0)
return r;
r = sd_bus_message_append(m, "ss", strempty(scope), "fail");
if (r < 0)
return r;
r = sd_bus_message_open_container(m, 'a', "(sv)");
if (r < 0)
return r;
if (!isempty(slice)) {
r = sd_bus_message_append(m, "(sv)", "Slice", "s", slice);
if (r < 0)
return r;
}
if (!isempty(description)) {
r = sd_bus_message_append(m, "(sv)", "Description", "s", description);
if (r < 0)
return r;
}
/* cgroup empty notification is not available in containers
* currently. To make this less problematic, let's shorten the
* stop timeout for machines, so that we don't wait
* forever. */
r = sd_bus_message_append(m, "(sv)", "TimeoutStopUSec", "t", 500 * USEC_PER_MSEC);
if (r < 0)
return r;
r = sd_bus_message_append(m, "(sv)", "PIDs", "au", 1, pid);
if (r < 0)
return r;
if (more_properties) {
r = sd_bus_message_copy(m, more_properties, true);
if (r < 0)
return r;
}
r = sd_bus_message_close_container(m);
if (r < 0)
return r;
r = sd_bus_message_append(m, "a(sa(sv))", 0);
if (r < 0)
return r;
r = sd_bus_call(manager->bus, m, 0, error, &reply);
if (r < 0)
return r;
if (job) {
const char *j;
char *copy;
r = sd_bus_message_read(reply, "o", &j);
if (r < 0)
return r;
copy = strdup(j);
if (!copy)
return -ENOMEM;
*job = copy;
}
return 1;
}
int manager_stop_unit(Manager *manager, const char *unit, sd_bus_error *error, char **job) {
_cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
int r;
assert(manager);
assert(unit);
r = sd_bus_call_method(
manager->bus,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
"org.freedesktop.systemd1.Manager",
"StopUnit",
error,
&reply,
"ss", unit, "fail");
if (r < 0) {
if (sd_bus_error_has_name(error, BUS_ERROR_NO_SUCH_UNIT) ||
sd_bus_error_has_name(error, BUS_ERROR_LOAD_FAILED)) {
if (job)
*job = NULL;
sd_bus_error_free(error);
return 0;
}
return r;
}
if (job) {
const char *j;
char *copy;
r = sd_bus_message_read(reply, "o", &j);
if (r < 0)
return r;
copy = strdup(j);
if (!copy)
return -ENOMEM;
*job = copy;
}
return 1;
}
int manager_kill_unit(Manager *manager, const char *unit, KillWho who, int signo, sd_bus_error *error) {
assert(manager);
assert(unit);
return sd_bus_call_method(
manager->bus,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
"org.freedesktop.systemd1.Manager",
"KillUnit",
error,
NULL,
"ssi", unit, who == KILL_LEADER ? "main" : "all", signo);
}
int manager_unit_is_active(Manager *manager, const char *unit) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
_cleanup_free_ char *path = NULL;
const char *state;
int r;
assert(manager);
assert(unit);
path = unit_dbus_path_from_name(unit);
if (!path)
return -ENOMEM;
r = sd_bus_get_property(
manager->bus,
"org.freedesktop.systemd1",
path,
"org.freedesktop.systemd1.Unit",
"ActiveState",
&error,
&reply,
"s");
if (r < 0) {
if (sd_bus_error_has_name(&error, SD_BUS_ERROR_NO_REPLY) ||
sd_bus_error_has_name(&error, SD_BUS_ERROR_DISCONNECTED))
return true;
if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_UNIT) ||
sd_bus_error_has_name(&error, BUS_ERROR_LOAD_FAILED))
return false;
return r;
}
r = sd_bus_message_read(reply, "s", &state);
if (r < 0)
return -EINVAL;
return !streq(state, "inactive") && !streq(state, "failed");
}
int manager_job_is_active(Manager *manager, const char *path) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
int r;
assert(manager);
assert(path);
r = sd_bus_get_property(
manager->bus,
"org.freedesktop.systemd1",
path,
"org.freedesktop.systemd1.Job",
"State",
&error,
&reply,
"s");
if (r < 0) {
if (sd_bus_error_has_name(&error, SD_BUS_ERROR_NO_REPLY) ||
sd_bus_error_has_name(&error, SD_BUS_ERROR_DISCONNECTED))
return true;
if (sd_bus_error_has_name(&error, SD_BUS_ERROR_UNKNOWN_OBJECT))
return false;
return r;
}
/* We don't actually care about the state really. The fact
* that we could read the job state is enough for us */
return true;
}
int manager_get_machine_by_pid(Manager *m, pid_t pid, Machine **machine) {
_cleanup_free_ char *unit = NULL;
Machine *mm;
int r;
assert(m);
assert(pid >= 1);
assert(machine);
r = cg_pid_get_unit(pid, &unit);
if (r < 0)
mm = hashmap_get(m->machine_leaders, UINT_TO_PTR(pid));
else
mm = hashmap_get(m->machine_units, unit);
if (!mm)
return 0;
*machine = mm;
return 1;
}
int manager_add_machine(Manager *m, const char *name, Machine **_machine) {
Machine *machine;
assert(m);
assert(name);
machine = hashmap_get(m->machines, name);
if (!machine) {
machine = machine_new(m, name);
if (!machine)
return -ENOMEM;
}
if (_machine)
*_machine = machine;
return 0;
}
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