blob: 875df1c2989db6aa0eab4bc92d9596dfb8829239 [file] [log] [blame]
Thomas Gleixner2874c5f2019-05-27 08:55:01 +02001// SPDX-License-Identifier: GPL-2.0-or-later
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/* 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
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 */
7
8#include <linux/module.h>
9#include <linux/signal.h>
Randy Dunlap4fc268d2006-01-11 12:17:47 -080010#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/errno.h>
12#include <linux/sched.h>
Ingo Molnar8703e8a2017-02-08 18:51:30 +010013#include <linux/sched/user.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/mm.h>
15#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#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>
Eric W. Biederman92f28d92013-03-15 01:03:33 -070024#include <linux/pid_namespace.h>
Pavel Emelyanovb4888932007-10-18 23:40:14 -070025#include <linux/pid.h>
26#include <linux/nsproxy.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090027#include <linux/slab.h>
Deepa Dinamani97184752019-02-02 07:34:51 -080028#include <linux/errqueue.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
Linus Torvalds7c0f6ba2016-12-24 11:46:01 -080030#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
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>
Daniel Wagnerd8429502013-01-21 21:09:00 +000037#include <net/cls_cgroup.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038
39
40/*
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090041 * Only allow a user to send credentials, that they could set with
Linus Torvalds1da177e2005-04-16 15:20:36 -070042 * setu(g)id.
43 */
44
45static __inline__ int scm_check_creds(struct ucred *creds)
46{
David Howells86a264a2008-11-14 10:39:18 +110047 const struct cred *cred = current_cred();
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060048 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;
David Howellsb6dff3e2008-11-14 10:39:16 +110053
Eric W. Biederman92f28d92013-03-15 01:03:33 -070054 if ((creds->pid == task_tgid_vnr(current) ||
Andy Lutomirskid6616842013-08-22 11:39:15 -070055 ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060056 ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) ||
Eric W. Biedermanc7b96ac2013-03-20 12:49:49 -070057 uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060058 ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) ||
Eric W. Biedermanc7b96ac2013-03-20 12:49:49 -070059 gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 return 0;
61 }
62 return -EPERM;
63}
64
65static 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
yuan linyu1ff8ceb2017-01-03 20:42:17 +080072 num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int);
Linus Torvalds1da177e2005-04-16 15:20:36 -070073
74 if (num <= 0)
75 return 0;
76
77 if (num > SCM_MAX_FD)
78 return -EINVAL;
79
80 if (!fpl)
81 {
82 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
83 if (!fpl)
84 return -ENOMEM;
85 *fplp = fpl;
86 fpl->count = 0;
Eric Dumazetbba14de2010-11-23 14:09:15 +000087 fpl->max = SCM_MAX_FD;
Hannes Frederic Sowa415e3d32016-02-03 02:11:03 +010088 fpl->user = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 }
90 fpp = &fpl->fp[fpl->count];
91
Eric Dumazetbba14de2010-11-23 14:09:15 +000092 if (fpl->count + num > fpl->max)
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 return -EINVAL;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090094
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 /*
96 * Verify the descriptors and increment the usage count.
97 */
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090098
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 for (i=0; i< num; i++)
100 {
101 int fd = fdp[i];
102 struct file *file;
103
Al Viro326be7b2011-03-13 17:08:22 -0400104 if (fd < 0 || !(file = fget_raw(fd)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 return -EBADF;
106 *fpp++ = file;
107 fpl->count++;
108 }
Hannes Frederic Sowa415e3d32016-02-03 02:11:03 +0100109
110 if (!fpl->user)
111 fpl->user = get_uid(current_user());
112
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 return num;
114}
115
116void __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;
Al Viro6120d3d2012-06-24 10:03:05 +0400123 for (i=fpl->count-1; i>=0; i--)
124 fput(fpl->fp[i]);
Hannes Frederic Sowa415e3d32016-02-03 02:11:03 +0100125 free_uid(fpl->user);
Al Viro6120d3d2012-06-24 10:03:05 +0400126 kfree(fpl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 }
128}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000129EXPORT_SYMBOL(__scm_destroy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
131int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
132{
133 struct cmsghdr *cmsg;
134 int err;
135
Gu Zhengf95b4142014-12-11 11:22:04 +0800136 for_each_cmsghdr(cmsg, msg) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 err = -EINVAL;
138
139 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
140 /* The first check was omitted in <= 2.2.5. The reasoning was
141 that parser checks cmsg_len in any case, so that
142 additional check would be work duplication.
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900143 But if cmsg_level is not SOL_SOCKET, we do not check
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 for too short ancillary data object at all! Oops.
145 OK, let's add it...
146 */
147 if (!CMSG_OK(msg, cmsg))
148 goto error;
149
150 if (cmsg->cmsg_level != SOL_SOCKET)
151 continue;
152
153 switch (cmsg->cmsg_type)
154 {
155 case SCM_RIGHTS:
Eric W. Biederman76dadd762010-02-28 01:20:36 +0000156 if (!sock->ops || sock->ops->family != PF_UNIX)
157 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 err=scm_fp_copy(cmsg, &p->fp);
159 if (err<0)
160 goto error;
161 break;
162 case SCM_CREDENTIALS:
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600163 {
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000164 struct ucred creds;
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600165 kuid_t uid;
166 kgid_t gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
168 goto error;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000169 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
170 err = scm_check_creds(&creds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 if (err)
172 goto error;
Eric W. Biederman257b5352010-06-13 03:32:34 +0000173
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000174 p->creds.pid = creds.pid;
175 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
Eric W. Biederman257b5352010-06-13 03:32:34 +0000176 struct pid *pid;
177 err = -ESRCH;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000178 pid = find_get_pid(creds.pid);
Eric W. Biederman257b5352010-06-13 03:32:34 +0000179 if (!pid)
180 goto error;
181 put_pid(p->pid);
182 p->pid = pid;
183 }
184
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600185 err = -EINVAL;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000186 uid = make_kuid(current_user_ns(), creds.uid);
187 gid = make_kgid(current_user_ns(), creds.gid);
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600188 if (!uid_valid(uid) || !gid_valid(gid))
189 goto error;
190
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000191 p->creds.uid = uid;
192 p->creds.gid = gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 break;
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600194 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 default:
196 goto error;
197 }
198 }
199
200 if (p->fp && !p->fp->count)
201 {
202 kfree(p->fp);
203 p->fp = NULL;
204 }
205 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900206
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207error:
208 scm_destroy(p);
209 return err;
210}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000211EXPORT_SYMBOL(__scm_send);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212
213int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
214{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 int cmlen = CMSG_LEN(len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
Christoph Hellwig1f466e12020-05-11 13:59:13 +0200217 if (msg->msg_flags & MSG_CMSG_COMPAT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 return put_cmsg_compat(msg, level, type, len, data);
219
Christoph Hellwig1f466e12020-05-11 13:59:13 +0200220 if (!msg->msg_control || msg->msg_controllen < sizeof(struct cmsghdr)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 msg->msg_flags |= MSG_CTRUNC;
222 return 0; /* XXX: return error? check spec. */
223 }
224 if (msg->msg_controllen < cmlen) {
225 msg->msg_flags |= MSG_CTRUNC;
226 cmlen = msg->msg_controllen;
227 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228
Christoph Hellwig1f466e12020-05-11 13:59:13 +0200229 if (msg->msg_control_is_user) {
230 struct cmsghdr __user *cm = msg->msg_control_user;
231 struct cmsghdr cmhdr;
232
233 cmhdr.cmsg_level = level;
234 cmhdr.cmsg_type = type;
235 cmhdr.cmsg_len = cmlen;
236 if (copy_to_user(cm, &cmhdr, sizeof cmhdr) ||
237 copy_to_user(CMSG_USER_DATA(cm), data, cmlen - sizeof(*cm)))
238 return -EFAULT;
239 } else {
240 struct cmsghdr *cm = msg->msg_control;
241
242 cm->cmsg_level = level;
243 cm->cmsg_type = type;
244 cm->cmsg_len = cmlen;
245 memcpy(CMSG_DATA(cm), data, cmlen - sizeof(*cm));
246 }
247
248 cmlen = min(CMSG_SPACE(len), msg->msg_controllen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 msg->msg_control += cmlen;
250 msg->msg_controllen -= cmlen;
Christoph Hellwig1f466e12020-05-11 13:59:13 +0200251 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000253EXPORT_SYMBOL(put_cmsg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254
Deepa Dinamani97184752019-02-02 07:34:51 -0800255void put_cmsg_scm_timestamping64(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
256{
257 struct scm_timestamping64 tss;
258 int i;
259
260 for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
261 tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
262 tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
263 }
264
265 put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_NEW, sizeof(tss), &tss);
266}
267EXPORT_SYMBOL(put_cmsg_scm_timestamping64);
268
269void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
270{
271 struct scm_timestamping tss;
272 int i;
273
Arnd Bergmann0309f982019-10-27 18:09:32 +0100274 for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
275 tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
276 tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
277 }
Deepa Dinamani97184752019-02-02 07:34:51 -0800278
279 put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_OLD, sizeof(tss), &tss);
280}
281EXPORT_SYMBOL(put_cmsg_scm_timestamping);
282
Christoph Hellwig2618d532020-05-11 13:59:12 +0200283static int __scm_install_fd(struct file *file, int __user *ufd, int o_flags)
284{
285 struct socket *sock;
286 int new_fd;
287 int error;
288
289 error = security_file_receive(file);
290 if (error)
291 return error;
292
293 new_fd = get_unused_fd_flags(o_flags);
294 if (new_fd < 0)
295 return new_fd;
296
297 error = put_user(new_fd, ufd);
298 if (error) {
299 put_unused_fd(new_fd);
300 return error;
301 }
302
303 /* Bump the usage count and install the file. */
304 sock = sock_from_file(file, &error);
305 if (sock) {
306 sock_update_netprioidx(&sock->sk->sk_cgrp_data);
307 sock_update_classid(&sock->sk->sk_cgrp_data);
308 }
309 fd_install(new_fd, get_file(file));
Christoph Hellwig6e8a4f92020-05-13 13:07:59 +0200310 return 0;
Christoph Hellwig2618d532020-05-11 13:59:12 +0200311}
312
313static int scm_max_fds(struct msghdr *msg)
314{
315 if (msg->msg_controllen <= sizeof(struct cmsghdr))
316 return 0;
317 return (msg->msg_controllen - sizeof(struct cmsghdr)) / sizeof(int);
318}
319
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
321{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700322 struct cmsghdr __user *cm
323 = (__force struct cmsghdr __user*)msg->msg_control;
Christoph Hellwig2618d532020-05-11 13:59:12 +0200324 int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
325 int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count);
326 int __user *cmsg_data = CMSG_USER_DATA(cm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 int err = 0, i;
328
Christoph Hellwig2618d532020-05-11 13:59:12 +0200329 if (msg->msg_flags & MSG_CMSG_COMPAT) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 scm_detach_fds_compat(msg, scm);
331 return;
332 }
333
Christoph Hellwig1f466e12020-05-11 13:59:13 +0200334 /* no use for FD passing from kernel space callers */
335 if (WARN_ON_ONCE(!msg->msg_control_is_user))
336 return;
337
Christoph Hellwig2618d532020-05-11 13:59:12 +0200338 for (i = 0; i < fdmax; i++) {
339 err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 if (err)
341 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 }
343
Christoph Hellwig2618d532020-05-11 13:59:12 +0200344 if (i > 0) {
345 int cmlen = CMSG_LEN(i * sizeof(int));
346
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700347 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 if (!err)
349 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
350 if (!err)
351 err = put_user(cmlen, &cm->cmsg_len);
352 if (!err) {
Christoph Hellwig2618d532020-05-11 13:59:12 +0200353 cmlen = CMSG_SPACE(i * sizeof(int));
Daniel Borkmann69003172015-11-20 00:11:56 +0100354 if (msg->msg_controllen < cmlen)
355 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 msg->msg_control += cmlen;
357 msg->msg_controllen -= cmlen;
358 }
359 }
Christoph Hellwig2618d532020-05-11 13:59:12 +0200360
361 if (i < scm->fp->count || (scm->fp->count && fdmax <= 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 msg->msg_flags |= MSG_CTRUNC;
363
364 /*
Christoph Hellwig2618d532020-05-11 13:59:12 +0200365 * All of the files that fit in the message have had their usage counts
366 * incremented, so we just free the list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 */
368 __scm_destroy(scm);
369}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000370EXPORT_SYMBOL(scm_detach_fds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371
372struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
373{
374 struct scm_fp_list *new_fpl;
375 int i;
376
377 if (!fpl)
378 return NULL;
379
Eric Dumazetbba14de2010-11-23 14:09:15 +0000380 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
381 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 if (new_fpl) {
Eric Dumazetbba14de2010-11-23 14:09:15 +0000383 for (i = 0; i < fpl->count; i++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 get_file(fpl->fp[i]);
Eric Dumazetbba14de2010-11-23 14:09:15 +0000385 new_fpl->max = new_fpl->count;
Hannes Frederic Sowa415e3d32016-02-03 02:11:03 +0100386 new_fpl->user = get_uid(fpl->user);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 }
388 return new_fpl;
389}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390EXPORT_SYMBOL(scm_fp_dup);