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Commit | Line | Data |
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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* scm.c - Socket level control messages processing. |
3 | * | |
4 | * Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> | |
5 | * Alignment and value checking mods by Craig Metz | |
1da177e4 LT |
6 | */ |
7 | ||
8 | #include <linux/module.h> | |
9 | #include <linux/signal.h> | |
4fc268d2 | 10 | #include <linux/capability.h> |
1da177e4 LT |
11 | #include <linux/errno.h> |
12 | #include <linux/sched.h> | |
8703e8a4 | 13 | #include <linux/sched/user.h> |
1da177e4 LT |
14 | #include <linux/mm.h> |
15 | #include <linux/kernel.h> | |
1da177e4 LT |
16 | #include <linux/stat.h> |
17 | #include <linux/socket.h> | |
18 | #include <linux/file.h> | |
19 | #include <linux/fcntl.h> | |
20 | #include <linux/net.h> | |
21 | #include <linux/interrupt.h> | |
22 | #include <linux/netdevice.h> | |
23 | #include <linux/security.h> | |
92f28d97 | 24 | #include <linux/pid_namespace.h> |
b488893a PE |
25 | #include <linux/pid.h> |
26 | #include <linux/nsproxy.h> | |
5a0e3ad6 | 27 | #include <linux/slab.h> |
9718475e | 28 | #include <linux/errqueue.h> |
1da177e4 | 29 | |
7c0f6ba6 | 30 | #include <linux/uaccess.h> |
1da177e4 LT |
31 | |
32 | #include <net/protocol.h> | |
33 | #include <linux/skbuff.h> | |
34 | #include <net/sock.h> | |
35 | #include <net/compat.h> | |
36 | #include <net/scm.h> | |
d8429506 | 37 | #include <net/cls_cgroup.h> |
1da177e4 LT |
38 | |
39 | ||
40 | /* | |
4ec93edb | 41 | * Only allow a user to send credentials, that they could set with |
1da177e4 LT |
42 | * setu(g)id. |
43 | */ | |
44 | ||
45 | static __inline__ int scm_check_creds(struct ucred *creds) | |
46 | { | |
86a264ab | 47 | const struct cred *cred = current_cred(); |
b2e4f544 EB |
48 | kuid_t uid = make_kuid(cred->user_ns, creds->uid); |
49 | kgid_t gid = make_kgid(cred->user_ns, creds->gid); | |
50 | ||
51 | if (!uid_valid(uid) || !gid_valid(gid)) | |
52 | return -EINVAL; | |
b6dff3ec | 53 | |
92f28d97 | 54 | if ((creds->pid == task_tgid_vnr(current) || |
d661684c | 55 | ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) && |
b2e4f544 | 56 | ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) || |
c7b96acf | 57 | uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) && |
b2e4f544 | 58 | ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) || |
c7b96acf | 59 | gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) { |
1da177e4 LT |
60 | return 0; |
61 | } | |
62 | return -EPERM; | |
63 | } | |
64 | ||
65 | static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp) | |
66 | { | |
67 | int *fdp = (int*)CMSG_DATA(cmsg); | |
68 | struct scm_fp_list *fpl = *fplp; | |
69 | struct file **fpp; | |
70 | int i, num; | |
71 | ||
1ff8cebf | 72 | num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int); |
1da177e4 LT |
73 | |
74 | if (num <= 0) | |
75 | return 0; | |
76 | ||
77 | if (num > SCM_MAX_FD) | |
78 | return -EINVAL; | |
79 | ||
80 | if (!fpl) | |
81 | { | |
2c6ad20b | 82 | fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL_ACCOUNT); |
1da177e4 LT |
83 | if (!fpl) |
84 | return -ENOMEM; | |
85 | *fplp = fpl; | |
86 | fpl->count = 0; | |
bba14de9 | 87 | fpl->max = SCM_MAX_FD; |
415e3d3e | 88 | fpl->user = NULL; |
1da177e4 LT |
89 | } |
90 | fpp = &fpl->fp[fpl->count]; | |
91 | ||
bba14de9 | 92 | if (fpl->count + num > fpl->max) |
1da177e4 | 93 | return -EINVAL; |
4ec93edb | 94 | |
1da177e4 LT |
95 | /* |
96 | * Verify the descriptors and increment the usage count. | |
97 | */ | |
4ec93edb | 98 | |
1da177e4 LT |
99 | for (i=0; i< num; i++) |
100 | { | |
101 | int fd = fdp[i]; | |
102 | struct file *file; | |
103 | ||
326be7b4 | 104 | if (fd < 0 || !(file = fget_raw(fd))) |
1da177e4 LT |
105 | return -EBADF; |
106 | *fpp++ = file; | |
107 | fpl->count++; | |
108 | } | |
415e3d3e HFS |
109 | |
110 | if (!fpl->user) | |
111 | fpl->user = get_uid(current_user()); | |
112 | ||
1da177e4 LT |
113 | return num; |
114 | } | |
115 | ||
116 | void __scm_destroy(struct scm_cookie *scm) | |
117 | { | |
118 | struct scm_fp_list *fpl = scm->fp; | |
119 | int i; | |
120 | ||
121 | if (fpl) { | |
122 | scm->fp = NULL; | |
6120d3db AV |
123 | for (i=fpl->count-1; i>=0; i--) |
124 | fput(fpl->fp[i]); | |
415e3d3e | 125 | free_uid(fpl->user); |
6120d3db | 126 | kfree(fpl); |
1da177e4 LT |
127 | } |
128 | } | |
9e34a5b5 | 129 | EXPORT_SYMBOL(__scm_destroy); |
1da177e4 LT |
130 | |
131 | int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p) | |
132 | { | |
1ded5e5a | 133 | const struct proto_ops *ops = READ_ONCE(sock->ops); |
1da177e4 LT |
134 | struct cmsghdr *cmsg; |
135 | int err; | |
136 | ||
f95b414e | 137 | for_each_cmsghdr(cmsg, msg) { |
1da177e4 LT |
138 | err = -EINVAL; |
139 | ||
140 | /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */ | |
141 | /* The first check was omitted in <= 2.2.5. The reasoning was | |
142 | that parser checks cmsg_len in any case, so that | |
143 | additional check would be work duplication. | |
4ec93edb | 144 | But if cmsg_level is not SOL_SOCKET, we do not check |
1da177e4 LT |
145 | for too short ancillary data object at all! Oops. |
146 | OK, let's add it... | |
147 | */ | |
148 | if (!CMSG_OK(msg, cmsg)) | |
149 | goto error; | |
150 | ||
151 | if (cmsg->cmsg_level != SOL_SOCKET) | |
152 | continue; | |
153 | ||
154 | switch (cmsg->cmsg_type) | |
155 | { | |
156 | case SCM_RIGHTS: | |
1ded5e5a | 157 | if (!ops || ops->family != PF_UNIX) |
76dadd76 | 158 | goto error; |
1da177e4 LT |
159 | err=scm_fp_copy(cmsg, &p->fp); |
160 | if (err<0) | |
161 | goto error; | |
162 | break; | |
163 | case SCM_CREDENTIALS: | |
b2e4f544 | 164 | { |
dbe9a417 | 165 | struct ucred creds; |
b2e4f544 EB |
166 | kuid_t uid; |
167 | kgid_t gid; | |
1da177e4 LT |
168 | if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred))) |
169 | goto error; | |
dbe9a417 EB |
170 | memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred)); |
171 | err = scm_check_creds(&creds); | |
1da177e4 LT |
172 | if (err) |
173 | goto error; | |
257b5358 | 174 | |
dbe9a417 EB |
175 | p->creds.pid = creds.pid; |
176 | if (!p->pid || pid_vnr(p->pid) != creds.pid) { | |
257b5358 EB |
177 | struct pid *pid; |
178 | err = -ESRCH; | |
dbe9a417 | 179 | pid = find_get_pid(creds.pid); |
257b5358 EB |
180 | if (!pid) |
181 | goto error; | |
182 | put_pid(p->pid); | |
183 | p->pid = pid; | |
184 | } | |
185 | ||
b2e4f544 | 186 | err = -EINVAL; |
dbe9a417 EB |
187 | uid = make_kuid(current_user_ns(), creds.uid); |
188 | gid = make_kgid(current_user_ns(), creds.gid); | |
b2e4f544 EB |
189 | if (!uid_valid(uid) || !gid_valid(gid)) |
190 | goto error; | |
191 | ||
dbe9a417 EB |
192 | p->creds.uid = uid; |
193 | p->creds.gid = gid; | |
1da177e4 | 194 | break; |
b2e4f544 | 195 | } |
1da177e4 LT |
196 | default: |
197 | goto error; | |
198 | } | |
199 | } | |
200 | ||
201 | if (p->fp && !p->fp->count) | |
202 | { | |
203 | kfree(p->fp); | |
204 | p->fp = NULL; | |
205 | } | |
206 | return 0; | |
4ec93edb | 207 | |
1da177e4 LT |
208 | error: |
209 | scm_destroy(p); | |
210 | return err; | |
211 | } | |
9e34a5b5 | 212 | EXPORT_SYMBOL(__scm_send); |
1da177e4 LT |
213 | |
214 | int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data) | |
215 | { | |
1da177e4 | 216 | int cmlen = CMSG_LEN(len); |
1da177e4 | 217 | |
1f466e1f | 218 | if (msg->msg_flags & MSG_CMSG_COMPAT) |
1da177e4 LT |
219 | return put_cmsg_compat(msg, level, type, len, data); |
220 | ||
1f466e1f | 221 | if (!msg->msg_control || msg->msg_controllen < sizeof(struct cmsghdr)) { |
1da177e4 LT |
222 | msg->msg_flags |= MSG_CTRUNC; |
223 | return 0; /* XXX: return error? check spec. */ | |
224 | } | |
225 | if (msg->msg_controllen < cmlen) { | |
226 | msg->msg_flags |= MSG_CTRUNC; | |
227 | cmlen = msg->msg_controllen; | |
228 | } | |
1f466e1f CH |
229 | |
230 | if (msg->msg_control_is_user) { | |
231 | struct cmsghdr __user *cm = msg->msg_control_user; | |
38ebcf50 | 232 | |
5f1eb1ff ED |
233 | check_object_size(data, cmlen - sizeof(*cm), true); |
234 | ||
38ebcf50 ED |
235 | if (!user_write_access_begin(cm, cmlen)) |
236 | goto efault; | |
237 | ||
e7ad33fa | 238 | unsafe_put_user(cmlen, &cm->cmsg_len, efault_end); |
38ebcf50 ED |
239 | unsafe_put_user(level, &cm->cmsg_level, efault_end); |
240 | unsafe_put_user(type, &cm->cmsg_type, efault_end); | |
241 | unsafe_copy_to_user(CMSG_USER_DATA(cm), data, | |
242 | cmlen - sizeof(*cm), efault_end); | |
243 | user_write_access_end(); | |
1f466e1f CH |
244 | } else { |
245 | struct cmsghdr *cm = msg->msg_control; | |
246 | ||
247 | cm->cmsg_level = level; | |
248 | cm->cmsg_type = type; | |
249 | cm->cmsg_len = cmlen; | |
250 | memcpy(CMSG_DATA(cm), data, cmlen - sizeof(*cm)); | |
251 | } | |
252 | ||
253 | cmlen = min(CMSG_SPACE(len), msg->msg_controllen); | |
c39ef213 KB |
254 | if (msg->msg_control_is_user) |
255 | msg->msg_control_user += cmlen; | |
256 | else | |
257 | msg->msg_control += cmlen; | |
1da177e4 | 258 | msg->msg_controllen -= cmlen; |
1f466e1f | 259 | return 0; |
38ebcf50 ED |
260 | |
261 | efault_end: | |
262 | user_write_access_end(); | |
263 | efault: | |
264 | return -EFAULT; | |
1da177e4 | 265 | } |
9e34a5b5 | 266 | EXPORT_SYMBOL(put_cmsg); |
1da177e4 | 267 | |
9718475e DD |
268 | void put_cmsg_scm_timestamping64(struct msghdr *msg, struct scm_timestamping_internal *tss_internal) |
269 | { | |
270 | struct scm_timestamping64 tss; | |
271 | int i; | |
272 | ||
273 | for (i = 0; i < ARRAY_SIZE(tss.ts); i++) { | |
274 | tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec; | |
275 | tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec; | |
276 | } | |
277 | ||
278 | put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_NEW, sizeof(tss), &tss); | |
279 | } | |
280 | EXPORT_SYMBOL(put_cmsg_scm_timestamping64); | |
281 | ||
282 | void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_internal *tss_internal) | |
283 | { | |
284 | struct scm_timestamping tss; | |
285 | int i; | |
286 | ||
0309f98f AB |
287 | for (i = 0; i < ARRAY_SIZE(tss.ts); i++) { |
288 | tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec; | |
289 | tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec; | |
290 | } | |
9718475e DD |
291 | |
292 | put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_OLD, sizeof(tss), &tss); | |
293 | } | |
294 | EXPORT_SYMBOL(put_cmsg_scm_timestamping); | |
295 | ||
2618d530 CH |
296 | static int scm_max_fds(struct msghdr *msg) |
297 | { | |
298 | if (msg->msg_controllen <= sizeof(struct cmsghdr)) | |
299 | return 0; | |
300 | return (msg->msg_controllen - sizeof(struct cmsghdr)) / sizeof(int); | |
301 | } | |
302 | ||
1da177e4 LT |
303 | void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm) |
304 | { | |
c0029de5 | 305 | struct cmsghdr __user *cm = |
c39ef213 | 306 | (__force struct cmsghdr __user *)msg->msg_control_user; |
c0029de5 | 307 | unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0; |
2618d530 CH |
308 | int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count); |
309 | int __user *cmsg_data = CMSG_USER_DATA(cm); | |
1da177e4 LT |
310 | int err = 0, i; |
311 | ||
c0029de5 KC |
312 | /* no use for FD passing from kernel space callers */ |
313 | if (WARN_ON_ONCE(!msg->msg_control_is_user)) | |
314 | return; | |
315 | ||
2618d530 | 316 | if (msg->msg_flags & MSG_CMSG_COMPAT) { |
1da177e4 LT |
317 | scm_detach_fds_compat(msg, scm); |
318 | return; | |
319 | } | |
320 | ||
2618d530 | 321 | for (i = 0; i < fdmax; i++) { |
eac9189c | 322 | err = scm_recv_one_fd(scm->fp->fp[i], cmsg_data + i, o_flags); |
deefa7f3 | 323 | if (err < 0) |
1da177e4 | 324 | break; |
1da177e4 LT |
325 | } |
326 | ||
c0029de5 | 327 | if (i > 0) { |
2618d530 CH |
328 | int cmlen = CMSG_LEN(i * sizeof(int)); |
329 | ||
effee6a0 | 330 | err = put_user(SOL_SOCKET, &cm->cmsg_level); |
1da177e4 LT |
331 | if (!err) |
332 | err = put_user(SCM_RIGHTS, &cm->cmsg_type); | |
333 | if (!err) | |
334 | err = put_user(cmlen, &cm->cmsg_len); | |
335 | if (!err) { | |
2618d530 | 336 | cmlen = CMSG_SPACE(i * sizeof(int)); |
6900317f DB |
337 | if (msg->msg_controllen < cmlen) |
338 | cmlen = msg->msg_controllen; | |
c39ef213 | 339 | msg->msg_control_user += cmlen; |
1da177e4 LT |
340 | msg->msg_controllen -= cmlen; |
341 | } | |
342 | } | |
2618d530 CH |
343 | |
344 | if (i < scm->fp->count || (scm->fp->count && fdmax <= 0)) | |
1da177e4 LT |
345 | msg->msg_flags |= MSG_CTRUNC; |
346 | ||
347 | /* | |
2618d530 CH |
348 | * All of the files that fit in the message have had their usage counts |
349 | * incremented, so we just free the list. | |
1da177e4 LT |
350 | */ |
351 | __scm_destroy(scm); | |
352 | } | |
9e34a5b5 | 353 | EXPORT_SYMBOL(scm_detach_fds); |
1da177e4 LT |
354 | |
355 | struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl) | |
356 | { | |
357 | struct scm_fp_list *new_fpl; | |
358 | int i; | |
359 | ||
360 | if (!fpl) | |
361 | return NULL; | |
362 | ||
bba14de9 | 363 | new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]), |
2c6ad20b | 364 | GFP_KERNEL_ACCOUNT); |
1da177e4 | 365 | if (new_fpl) { |
bba14de9 | 366 | for (i = 0; i < fpl->count; i++) |
1da177e4 | 367 | get_file(fpl->fp[i]); |
bba14de9 | 368 | new_fpl->max = new_fpl->count; |
415e3d3e | 369 | new_fpl->user = get_uid(fpl->user); |
1da177e4 LT |
370 | } |
371 | return new_fpl; | |
372 | } | |
1da177e4 | 373 | EXPORT_SYMBOL(scm_fp_dup); |