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core: add user/group resolution varlink interface to PID 1
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5 files changed

+329
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5 files changed

+329
-1
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‎src/core/core-varlink.c‎

Lines changed: 310 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,310 @@
1+
/* SPDX-License-Identifier: LGPL-2.1+ */
2+
3+
#include "core-varlink.h"
4+
#include "mkdir.h"
5+
#include "user-util.h"
6+
#include "varlink.h"
7+
8+
typedef struct LookupParameters {
9+
const char *user_name;
10+
const char *group_name;
11+
union {
12+
uid_t uid;
13+
gid_t gid;
14+
};
15+
const char *service;
16+
} LookupParameters;
17+
18+
static int build_user_json(const char *user_name, uid_t uid, JsonVariant **ret) {
19+
assert(user_name);
20+
assert(uid_is_valid(uid));
21+
assert(ret);
22+
23+
return json_build(ret, JSON_BUILD_OBJECT(
24+
JSON_BUILD_PAIR("record", JSON_BUILD_OBJECT(
25+
JSON_BUILD_PAIR("userName", JSON_BUILD_STRING(user_name)),
26+
JSON_BUILD_PAIR("uid", JSON_BUILD_UNSIGNED(uid)),
27+
JSON_BUILD_PAIR("gid", JSON_BUILD_UNSIGNED(uid)),
28+
JSON_BUILD_PAIR("realName", JSON_BUILD_STRING("Dynamic User")),
29+
JSON_BUILD_PAIR("homeDirectory", JSON_BUILD_STRING("/")),
30+
JSON_BUILD_PAIR("shell", JSON_BUILD_STRING(NOLOGIN)),
31+
JSON_BUILD_PAIR("locked", JSON_BUILD_BOOLEAN(true)),
32+
JSON_BUILD_PAIR("service", JSON_BUILD_STRING("io.systemd.DynamicUser")),
33+
JSON_BUILD_PAIR("disposition", JSON_BUILD_STRING("dynamic"))))));
34+
}
35+
36+
static bool user_match_lookup_parameters(LookupParameters *p, const char *name, uid_t uid) {
37+
assert(p);
38+
39+
if (p->user_name && !streq(name, p->user_name))
40+
return false;
41+
42+
if (uid_is_valid(p->uid) && uid != p->uid)
43+
return false;
44+
45+
return true;
46+
}
47+
48+
static int vl_method_get_user_record(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
49+
50+
static const JsonDispatch dispatch_table[] = {
51+
{ "uid", JSON_VARIANT_UNSIGNED, json_dispatch_uid_gid, offsetof(LookupParameters, uid), 0 },
52+
{ "userName", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, user_name), JSON_SAFE },
53+
{ "service", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, service), 0 },
54+
{}
55+
};
56+
57+
_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
58+
LookupParameters p = {
59+
.uid = UID_INVALID,
60+
};
61+
_cleanup_free_ char *found_name = NULL;
62+
uid_t found_uid = UID_INVALID, uid;
63+
Manager *m = userdata;
64+
const char *un;
65+
int r;
66+
67+
assert(parameters);
68+
assert(m);
69+
70+
r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
71+
if (r < 0)
72+
return r;
73+
74+
if (!streq_ptr(p.service, "io.systemd.DynamicUser"))
75+
return varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
76+
77+
if (uid_is_valid(p.uid))
78+
r = dynamic_user_lookup_uid(m, p.uid, &found_name);
79+
else if (p.user_name)
80+
r = dynamic_user_lookup_name(m, p.user_name, &found_uid);
81+
else {
82+
Iterator i;
83+
DynamicUser *d;
84+
85+
HASHMAP_FOREACH(d, m->dynamic_users, i) {
86+
r = dynamic_user_current(d, &uid);
87+
if (r == -EAGAIN) /* not realized yet? */
88+
continue;
89+
if (r < 0)
90+
return r;
91+
92+
if (!user_match_lookup_parameters(&p, d->name, uid))
93+
continue;
94+
95+
if (v) {
96+
r = varlink_notify(link, v);
97+
if (r < 0)
98+
return r;
99+
100+
v = json_variant_unref(v);
101+
}
102+
103+
r = build_user_json(d->name, uid, &v);
104+
if (r < 0)
105+
return r;
106+
}
107+
108+
if (!v)
109+
return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
110+
111+
return varlink_reply(link, v);
112+
}
113+
if (r == -ESRCH)
114+
return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
115+
if (r < 0)
116+
return r;
117+
118+
uid = uid_is_valid(found_uid) ? found_uid : p.uid;
119+
un = found_name ?: p.user_name;
120+
121+
if (!user_match_lookup_parameters(&p, un, uid))
122+
return varlink_error(link, "io.systemd.UserDatabase.ConflictingRecordFound", NULL);
123+
124+
r = build_user_json(un, uid, &v);
125+
if (r < 0)
126+
return r;
127+
128+
return varlink_reply(link, v);
129+
}
130+
131+
static int build_group_json(const char *group_name, gid_t gid, JsonVariant **ret) {
132+
assert(group_name);
133+
assert(gid_is_valid(gid));
134+
assert(ret);
135+
136+
return json_build(ret, JSON_BUILD_OBJECT(
137+
JSON_BUILD_PAIR("record", JSON_BUILD_OBJECT(
138+
JSON_BUILD_PAIR("groupName", JSON_BUILD_STRING(group_name)),
139+
JSON_BUILD_PAIR("gid", JSON_BUILD_UNSIGNED(gid)),
140+
JSON_BUILD_PAIR("service", JSON_BUILD_STRING("io.systemd.DynamicUser")),
141+
JSON_BUILD_PAIR("disposition", JSON_BUILD_STRING("dynamic"))))));
142+
}
143+
144+
static bool group_match_lookup_parameters(LookupParameters *p, const char *name, gid_t gid) {
145+
assert(p);
146+
147+
if (p->group_name && !streq(name, p->group_name))
148+
return false;
149+
150+
if (gid_is_valid(p->gid) && gid != p->gid)
151+
return false;
152+
153+
return true;
154+
}
155+
156+
static int vl_method_get_group_record(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
157+
158+
static const JsonDispatch dispatch_table[] = {
159+
{ "gid", JSON_VARIANT_UNSIGNED, json_dispatch_uid_gid, offsetof(LookupParameters, gid), 0 },
160+
{ "groupName", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, group_name), JSON_SAFE },
161+
{ "service", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, service), 0 },
162+
{}
163+
};
164+
165+
_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
166+
LookupParameters p = {
167+
.gid = GID_INVALID,
168+
};
169+
_cleanup_free_ char *found_name = NULL;
170+
uid_t found_gid = GID_INVALID, gid;
171+
Manager *m = userdata;
172+
const char *gn;
173+
int r;
174+
175+
assert(parameters);
176+
assert(m);
177+
178+
r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
179+
if (r < 0)
180+
return r;
181+
182+
if (!streq_ptr(p.service, "io.systemd.DynamicUser"))
183+
return varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
184+
185+
if (gid_is_valid(p.gid))
186+
r = dynamic_user_lookup_uid(m, (uid_t) p.gid, &found_name);
187+
else if (p.group_name)
188+
r = dynamic_user_lookup_name(m, p.group_name, (uid_t*) &found_gid);
189+
else {
190+
DynamicUser *d;
191+
Iterator i;
192+
193+
HASHMAP_FOREACH(d, m->dynamic_users, i) {
194+
uid_t uid;
195+
196+
r = dynamic_user_current(d, &uid);
197+
if (r == -EAGAIN)
198+
continue;
199+
if (r < 0)
200+
return r;
201+
202+
if (!group_match_lookup_parameters(&p, d->name, (gid_t) uid))
203+
continue;
204+
205+
if (v) {
206+
r = varlink_notify(link, v);
207+
if (r < 0)
208+
return r;
209+
210+
v = json_variant_unref(v);
211+
}
212+
213+
r = build_group_json(d->name, (gid_t) uid, &v);
214+
if (r < 0)
215+
return r;
216+
}
217+
218+
if (!v)
219+
return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
220+
221+
return varlink_reply(link, v);
222+
}
223+
if (r == -ESRCH)
224+
return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
225+
if (r < 0)
226+
return r;
227+
228+
gid = gid_is_valid(found_gid) ? found_gid : p.gid;
229+
gn = found_name ?: p.group_name;
230+
231+
if (!group_match_lookup_parameters(&p, gn, gid))
232+
return varlink_error(link, "io.systemd.UserDatabase.ConflictingRecordFound", NULL);
233+
234+
r = build_group_json(gn, gid, &v);
235+
if (r < 0)
236+
return r;
237+
238+
return varlink_reply(link, v);
239+
}
240+
241+
static int vl_method_get_memberships(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
242+
243+
static const JsonDispatch dispatch_table[] = {
244+
{ "userName", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, user_name), JSON_SAFE },
245+
{ "groupName", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, group_name), JSON_SAFE },
246+
{ "service", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, service), 0 },
247+
{}
248+
};
249+
250+
LookupParameters p = {};
251+
int r;
252+
253+
assert(parameters);
254+
255+
r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
256+
if (r < 0)
257+
return r;
258+
259+
if (!streq_ptr(p.service, "io.systemd.DynamicUser"))
260+
return varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
261+
262+
/* We don't support auxiliary groups with dynamic users. */
263+
return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
264+
}
265+
266+
int manager_varlink_init(Manager *m) {
267+
_cleanup_(varlink_server_unrefp) VarlinkServer *s = NULL;
268+
int r;
269+
270+
assert(m);
271+
272+
if (m->varlink_server)
273+
return 0;
274+
275+
if (!MANAGER_IS_SYSTEM(m))
276+
return 0;
277+
278+
r = varlink_server_new(&s, VARLINK_SERVER_ACCOUNT_UID);
279+
if (r < 0)
280+
return log_error_errno(r, "Failed to allocate varlink server object: %m");
281+
282+
varlink_server_set_userdata(s, m);
283+
284+
r = varlink_server_bind_method_many(
285+
s,
286+
"io.systemd.UserDatabase.GetUserRecord", vl_method_get_user_record,
287+
"io.systemd.UserDatabase.GetGroupRecord", vl_method_get_group_record,
288+
"io.systemd.UserDatabase.GetMemberships", vl_method_get_memberships);
289+
if (r < 0)
290+
return log_error_errno(r, "Failed to register varlink methods: %m");
291+
292+
(void) mkdir_p("/run/systemd/userdb", 0755);
293+
294+
r = varlink_server_listen_address(s, "/run/systemd/userdb/io.systemd.DynamicUser", 0666);
295+
if (r < 0)
296+
return log_error_errno(r, "Failed to bind to varlink socket: %m");
297+
298+
r = varlink_server_attach_event(s, m->event, SD_EVENT_PRIORITY_NORMAL);
299+
if (r < 0)
300+
return log_error_errno(r, "Failed to attach varlink connection to event loop: %m");
301+
302+
m->varlink_server = TAKE_PTR(s);
303+
return 0;
304+
}
305+
306+
void manager_varlink_done(Manager *m) {
307+
assert(m);
308+
309+
m->varlink_server = varlink_server_unref(m->varlink_server);
310+
}

‎src/core/core-varlink.h‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,7 @@
1+
/* SPDX-License-Identifier: LGPL-2.1+ */
2+
#pragma once
3+
4+
#include "manager.h"
5+
6+
int manager_varlink_init(Manager *m);
7+
void manager_varlink_done(Manager *m);

‎src/core/manager.c‎

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,7 @@
2929
#include "bus-util.h"
3030
#include "clean-ipc.h"
3131
#include "clock-util.h"
32+
#include "core-varlink.h"
3233
#include "dbus-job.h"
3334
#include "dbus-manager.h"
3435
#include "dbus-unit.h"
@@ -44,8 +45,8 @@
4445
#include "fileio.h"
4546
#include "fs-util.h"
4647
#include "hashmap.h"
47-
#include "io-util.h"
4848
#include "install.h"
49+
#include "io-util.h"
4950
#include "label.h"
5051
#include "locale-setup.h"
5152
#include "log.h"
@@ -1346,6 +1347,7 @@ Manager* manager_free(Manager *m) {
13461347
lookup_paths_flush_generator(&m->lookup_paths);
13471348

13481349
bus_done(m);
1350+
manager_varlink_done(m);
13491351

13501352
exec_runtime_vacuum(m);
13511353
hashmap_free(m->exec_runtime_by_id);
@@ -1703,6 +1705,10 @@ int manager_startup(Manager *m, FILE *serialization, FDSet *fds) {
17031705
log_warning_errno(r, "Failed to deserialized tracked clients, ignoring: %m");
17041706
m->deserialized_subscribed = strv_free(m->deserialized_subscribed);
17051707

1708+
r = manager_varlink_init(m);
1709+
if (r < 0)
1710+
log_warning_errno(r, "Failed to set up Varlink server, ignoring: %m");
1711+
17061712
/* Third, fire things up! */
17071713
manager_coldplug(m);
17081714

‎src/core/manager.h‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,7 @@
1616
#include "list.h"
1717
#include "prioq.h"
1818
#include "ratelimit.h"
19+
#include "varlink.h"
1920

2021
struct libmnt_monitor;
2122
typedef struct Unit Unit;
@@ -422,6 +423,8 @@ struct Manager {
422423
unsigned notifygen;
423424

424425
bool honor_device_enumeration;
426+
427+
VarlinkServer *varlink_server;
425428
};
426429

427430
static inline usec_t manager_default_timeout_abort_usec(Manager *m) {

‎src/core/meson.build‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,8 @@ libcore_sources = '''
2222
bpf-firewall.h
2323
cgroup.c
2424
cgroup.h
25+
core-varlink.c
26+
core-varlink.h
2527
dbus-automount.c
2628
dbus-automount.h
2729
dbus-cgroup.c

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