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1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ | |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2011 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 2 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
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 | General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <assert.h> | |
23 | #include <sys/acl.h> | |
24 | #include <acl/libacl.h> | |
25 | #include <errno.h> | |
26 | #include <string.h> | |
27 | ||
28 | #include "logind-acl.h" | |
29 | #include "util.h" | |
30 | ||
31 | static int find_acl(acl_t acl, uid_t uid, acl_entry_t *entry) { | |
32 | acl_entry_t i; | |
33 | int found; | |
34 | ||
35 | assert(acl); | |
36 | assert(entry); | |
37 | ||
38 | for (found = acl_get_entry(acl, ACL_FIRST_ENTRY, &i); | |
39 | found > 0; | |
40 | found = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) { | |
41 | ||
42 | acl_tag_t tag; | |
43 | uid_t *u; | |
44 | bool b; | |
45 | ||
46 | if (acl_get_tag_type(i, &tag) < 0) | |
47 | return -errno; | |
48 | ||
49 | if (tag != ACL_USER) | |
50 | continue; | |
51 | ||
52 | u = acl_get_qualifier(i); | |
53 | if (!u) | |
54 | return -errno; | |
55 | ||
56 | b = *u == uid; | |
57 | acl_free(u); | |
58 | ||
59 | if (b) { | |
60 | *entry = i; | |
61 | return 1; | |
62 | } | |
63 | } | |
64 | ||
65 | if (found < 0) | |
66 | return -errno; | |
67 | ||
68 | return 0; | |
69 | } | |
70 | ||
71 | static int flush_acl(acl_t acl) { | |
72 | acl_entry_t i; | |
73 | int found; | |
74 | bool changed = false; | |
75 | ||
76 | assert(acl); | |
77 | ||
78 | for (found = acl_get_entry(acl, ACL_FIRST_ENTRY, &i); | |
79 | found > 0; | |
80 | found = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) { | |
81 | ||
82 | acl_tag_t tag; | |
83 | ||
84 | if (acl_get_tag_type(i, &tag) < 0) | |
85 | return -errno; | |
86 | ||
87 | if (tag != ACL_USER) | |
88 | continue; | |
89 | ||
90 | if (acl_delete_entry(acl, i) < 0) | |
91 | return -errno; | |
92 | ||
93 | changed = true; | |
94 | } | |
95 | ||
96 | if (found < 0) | |
97 | return -errno; | |
98 | ||
99 | return changed; | |
100 | } | |
101 | ||
102 | int devnode_acl(const char *path, | |
103 | bool flush, | |
104 | bool del, uid_t old_uid, | |
105 | bool add, uid_t new_uid) { | |
106 | ||
107 | acl_t acl; | |
108 | int r = 0; | |
109 | bool changed = false; | |
110 | ||
111 | assert(path); | |
112 | ||
113 | acl = acl_get_file(path, ACL_TYPE_ACCESS); | |
114 | if (!acl) | |
115 | return -errno; | |
116 | ||
117 | if (flush) { | |
118 | ||
119 | r = flush_acl(acl); | |
120 | if (r < 0) | |
121 | goto finish; | |
122 | if (r > 0) | |
123 | changed = true; | |
124 | ||
125 | } else if (del && old_uid > 0) { | |
126 | acl_entry_t entry; | |
127 | ||
128 | r = find_acl(acl, old_uid, &entry); | |
129 | if (r < 0) | |
130 | goto finish; | |
131 | ||
132 | if (r > 0) { | |
133 | if (acl_delete_entry(acl, entry) < 0) { | |
134 | r = -errno; | |
135 | goto finish; | |
136 | } | |
137 | ||
138 | changed = true; | |
139 | } | |
140 | } | |
141 | ||
142 | if (add && new_uid > 0) { | |
143 | acl_entry_t entry; | |
144 | acl_permset_t permset; | |
145 | int rd, wt; | |
146 | ||
147 | r = find_acl(acl, new_uid, &entry); | |
148 | if (r < 0) | |
149 | goto finish; | |
150 | ||
151 | if (r == 0) { | |
152 | if (acl_create_entry(&acl, &entry) < 0) { | |
153 | r = -errno; | |
154 | goto finish; | |
155 | } | |
156 | ||
157 | if (acl_set_tag_type(entry, ACL_USER) < 0 || | |
158 | acl_set_qualifier(entry, &new_uid) < 0) { | |
159 | r = -errno; | |
160 | goto finish; | |
161 | } | |
162 | } | |
163 | ||
164 | if (acl_get_permset(entry, &permset) < 0) { | |
165 | r = -errno; | |
166 | goto finish; | |
167 | } | |
168 | ||
169 | rd = acl_get_perm(permset, ACL_READ); | |
170 | if (rd < 0) { | |
171 | r = -errno; | |
172 | goto finish; | |
173 | } | |
174 | ||
175 | wt = acl_get_perm(permset, ACL_WRITE); | |
176 | if (wt < 0) { | |
177 | r = -errno; | |
178 | goto finish; | |
179 | } | |
180 | ||
181 | if (!rd || !wt) { | |
182 | ||
183 | if (acl_add_perm(permset, ACL_READ|ACL_WRITE) < 0) { | |
184 | r = -errno; | |
185 | goto finish; | |
186 | } | |
187 | ||
188 | changed = true; | |
189 | } | |
190 | } | |
191 | ||
192 | if (!changed) | |
193 | goto finish; | |
194 | ||
195 | if (acl_calc_mask(&acl) < 0) { | |
196 | r = -errno; | |
197 | goto finish; | |
198 | } | |
199 | ||
200 | if (acl_set_file(path, ACL_TYPE_ACCESS, acl) < 0) { | |
201 | r = -errno; | |
202 | goto finish; | |
203 | } | |
204 | ||
205 | r = 0; | |
206 | ||
207 | finish: | |
208 | acl_free(acl); | |
209 | ||
210 | return r; | |
211 | } | |
212 | ||
213 | int devnode_acl_all(struct udev *udev, | |
214 | const char *seat, | |
215 | bool flush, | |
216 | bool del, uid_t old_uid, | |
217 | bool add, uid_t new_uid) { | |
218 | ||
219 | struct udev_list_entry *item = NULL, *first = NULL; | |
220 | struct udev_enumerate *e; | |
221 | int r; | |
222 | ||
223 | assert(udev); | |
224 | ||
225 | if (isempty(seat)) | |
226 | seat = "seat0"; | |
227 | ||
228 | e = udev_enumerate_new(udev); | |
229 | if (!e) | |
230 | return -ENOMEM; | |
231 | ||
232 | /* We can only match by one tag in libudev. We choose | |
233 | * "uaccess" for that. If we could match for two tags here we | |
234 | * could add the seat name as second match tag, but this would | |
235 | * be hardly optimizable in libudev, and hence checking the | |
236 | * second tag manually in our loop is a good solution. */ | |
237 | ||
238 | r = udev_enumerate_add_match_tag(e, "uaccess"); | |
239 | if (r < 0) | |
240 | goto finish; | |
241 | ||
242 | r = udev_enumerate_scan_devices(e); | |
243 | if (r < 0) | |
244 | goto finish; | |
245 | ||
246 | first = udev_enumerate_get_list_entry(e); | |
247 | udev_list_entry_foreach(item, first) { | |
248 | struct udev_device *d; | |
249 | const char *node, *sn; | |
250 | ||
251 | d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)); | |
252 | if (!d) { | |
253 | r = -ENOMEM; | |
254 | goto finish; | |
255 | } | |
256 | ||
257 | sn = udev_device_get_property_value(d, "ID_SEAT"); | |
258 | if (isempty(sn)) | |
259 | sn = "seat0"; | |
260 | ||
261 | if (!streq(seat, sn)) { | |
262 | udev_device_unref(d); | |
263 | continue; | |
264 | } | |
265 | ||
266 | node = udev_device_get_devnode(d); | |
267 | if (!node) { | |
268 | /* In case people mistag devices with nodes, we need to ignore this */ | |
269 | udev_device_unref(d); | |
270 | continue; | |
271 | } | |
272 | ||
273 | log_debug("Fixing up %s for seat %s...", node, sn); | |
274 | ||
275 | r = devnode_acl(node, flush, del, old_uid, add, new_uid); | |
276 | udev_device_unref(d); | |
277 | ||
278 | if (r < 0) | |
279 | goto finish; | |
280 | } | |
281 | ||
282 | finish: | |
283 | if (e) | |
284 | udev_enumerate_unref(e); | |
285 | ||
286 | return r; | |
287 | } |