1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2012 Dan Walsh
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
22 #include "selinux-access.h"
28 #include <selinux/selinux.h>
29 #include <selinux/avc.h>
38 #include "selinux-util.h"
41 #include "path-util.h"
43 static bool initialized
= false;
52 Any time an access gets denied this callback will be called
53 with the audit data. We then need to just copy the audit data into the msgbuf.
55 static int audit_callback(
61 const struct audit_info
*audit
= auditdata
;
62 uid_t uid
= 0, login_uid
= 0;
64 char login_uid_buf
[DECIMAL_STR_MAX(uid_t
) + 1] = "n/a";
65 char uid_buf
[DECIMAL_STR_MAX(uid_t
) + 1] = "n/a";
66 char gid_buf
[DECIMAL_STR_MAX(gid_t
) + 1] = "n/a";
68 if (sd_bus_creds_get_audit_login_uid(audit
->creds
, &login_uid
) >= 0)
69 xsprintf(login_uid_buf
, UID_FMT
, login_uid
);
70 if (sd_bus_creds_get_euid(audit
->creds
, &uid
) >= 0)
71 xsprintf(uid_buf
, UID_FMT
, uid
);
72 if (sd_bus_creds_get_egid(audit
->creds
, &gid
) >= 0)
73 xsprintf(gid_buf
, GID_FMT
, gid
);
75 snprintf(msgbuf
, msgbufsize
,
76 "auid=%s uid=%s gid=%s%s%s%s%s%s%s",
77 login_uid_buf
, uid_buf
, gid_buf
,
78 audit
->path
? " path=\"" : "", strempty(audit
->path
), audit
->path
? "\"" : "",
79 audit
->cmdline
? " cmdline=\"" : "", strempty(audit
->cmdline
), audit
->cmdline
? "\"" : "");
84 static int callback_type_to_priority(int type
) {
103 libselinux uses this callback when access gets denied or other
104 events happen. If audit is turned on, messages will be reported
105 using audit netlink, otherwise they will be logged using the usual
108 Code copied from dbus and modified.
110 _printf_(2, 3) static int log_callback(int type
, const char *fmt
, ...) {
119 _cleanup_free_
char *buf
= NULL
;
123 r
= vasprintf(&buf
, fmt
, ap
);
127 audit_log_user_avc_message(fd
, AUDIT_USER_AVC
, buf
, NULL
, NULL
, NULL
, 0);
134 log_internalv(LOG_AUTH
| callback_type_to_priority(type
),
135 0, __FILE__
, __LINE__
, __FUNCTION__
, fmt
, ap
);
142 Function must be called once to initialize the SELinux AVC environment.
144 If you want to cleanup memory you should need to call selinux_access_finish.
146 static int access_init(void) {
149 if (avc_open(NULL
, 0))
150 return log_error_errno(errno
, "avc_open() failed: %m");
152 selinux_set_callback(SELINUX_CB_AUDIT
, (union selinux_callback
) audit_callback
);
153 selinux_set_callback(SELINUX_CB_LOG
, (union selinux_callback
) log_callback
);
155 if (security_getenforce() < 0){
163 static int mac_selinux_access_init(sd_bus_error
*error
) {
169 if (!mac_selinux_use())
174 return sd_bus_error_set(error
, SD_BUS_ERROR_ACCESS_DENIED
, "Failed to initialize SELinux.");
181 void mac_selinux_access_free(void) {
193 This function communicates with the kernel to check whether or not it should
195 If the machine is in permissive mode it will return ok. Audit messages will
196 still be generated if the access would be denied in enforcing mode.
198 int mac_selinux_generic_access_check(
199 sd_bus_message
*message
,
201 const char *permission
,
202 sd_bus_error
*error
) {
205 _cleanup_bus_creds_unref_ sd_bus_creds
*creds
= NULL
;
206 const char *tclass
= NULL
, *scon
= NULL
;
207 struct audit_info audit_info
= {};
208 _cleanup_free_
char *cl
= NULL
;
209 security_context_t fcon
= NULL
;
210 char **cmdline
= NULL
;
217 if (!mac_selinux_use())
220 r
= mac_selinux_access_init(error
);
224 r
= sd_bus_query_sender_creds(
226 SD_BUS_CREDS_PID
|SD_BUS_CREDS_EUID
|SD_BUS_CREDS_EGID
|
227 SD_BUS_CREDS_CMDLINE
|SD_BUS_CREDS_AUDIT_LOGIN_UID
|
228 SD_BUS_CREDS_SELINUX_CONTEXT
|
229 SD_BUS_CREDS_AUGMENT
/* get more bits from /proc */,
234 /* The SELinux context is something we really should have
235 * gotten directly from the message or sender, and not be an
236 * augmented field. If it was augmented we cannot use it for
237 * authorization, since this is racy and vulnerable. Let's add
238 * an extra check, just in case, even though this really
239 * shouldn't be possible. */
240 assert_return((sd_bus_creds_get_augmented_mask(creds
) & SD_BUS_CREDS_SELINUX_CONTEXT
) == 0, -EPERM
);
242 r
= sd_bus_creds_get_selinux_context(creds
, &scon
);
247 /* Get the file context of the unit file */
249 r
= getfilecon(path
, &fcon
);
251 r
= sd_bus_error_setf(error
, SD_BUS_ERROR_ACCESS_DENIED
, "Failed to get file context on %s.", path
);
259 r
= sd_bus_error_setf(error
, SD_BUS_ERROR_ACCESS_DENIED
, "Failed to get current context.");
266 sd_bus_creds_get_cmdline(creds
, &cmdline
);
267 cl
= strv_join(cmdline
, " ");
269 audit_info
.creds
= creds
;
270 audit_info
.path
= path
;
271 audit_info
.cmdline
= cl
;
273 r
= selinux_check_access(scon
, fcon
, tclass
, permission
, &audit_info
);
275 r
= sd_bus_error_setf(error
, SD_BUS_ERROR_ACCESS_DENIED
, "SELinux policy denies access.");
277 log_debug("SELinux access check scon=%s tcon=%s tclass=%s perm=%s path=%s cmdline=%s: %i", scon
, fcon
, tclass
, permission
, path
, cl
, r
);
282 if (r
< 0 && security_getenforce() != 1) {
283 sd_bus_error_free(error
);
293 int mac_selinux_unit_access_check_strv(
295 sd_bus_message
*message
,
297 const char *permission
,
298 sd_bus_error
*error
) {
305 STRV_FOREACH(i
, units
) {
307 r
= manager_load_unit(m
, NULL
, *i
, error
, &u
);
309 r
= manager_load_unit(m
, *i
, NULL
, error
, &u
);
312 r
= mac_selinux_unit_access_check(u
, message
, permission
, error
);