blob: b442e7e25e601b19a8237d1a90efbaa1d572fc19 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* scm.c - Socket level control messages processing.
2 *
3 * Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
4 * Alignment and value checking mods by Craig Metz
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/signal.h>
Randy Dunlap4fc268d2006-01-11 12:17:47 -080014#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/errno.h>
16#include <linux/sched.h>
17#include <linux/mm.h>
18#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/stat.h>
20#include <linux/socket.h>
21#include <linux/file.h>
22#include <linux/fcntl.h>
23#include <linux/net.h>
24#include <linux/interrupt.h>
25#include <linux/netdevice.h>
26#include <linux/security.h>
Eric W. Biederman92f28d92013-03-15 01:03:33 -070027#include <linux/pid_namespace.h>
Pavel Emelyanovb4888932007-10-18 23:40:14 -070028#include <linux/pid.h>
29#include <linux/nsproxy.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090030#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <asm/uaccess.h>
33
34#include <net/protocol.h>
35#include <linux/skbuff.h>
36#include <net/sock.h>
37#include <net/compat.h>
38#include <net/scm.h>
Daniel Wagnerd8429502013-01-21 21:09:00 +000039#include <net/cls_cgroup.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
41
42/*
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090043 * Only allow a user to send credentials, that they could set with
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 * setu(g)id.
45 */
46
47static __inline__ int scm_check_creds(struct ucred *creds)
48{
David Howells86a264a2008-11-14 10:39:18 +110049 const struct cred *cred = current_cred();
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060050 kuid_t uid = make_kuid(cred->user_ns, creds->uid);
51 kgid_t gid = make_kgid(cred->user_ns, creds->gid);
52
53 if (!uid_valid(uid) || !gid_valid(gid))
54 return -EINVAL;
David Howellsb6dff3e2008-11-14 10:39:16 +110055
Eric W. Biederman92f28d92013-03-15 01:03:33 -070056 if ((creds->pid == task_tgid_vnr(current) ||
Andy Lutomirskid6616842013-08-22 11:39:15 -070057 ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060058 ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) ||
Eric W. Biedermanc7b96ac2013-03-20 12:49:49 -070059 uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060060 ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) ||
Eric W. Biedermanc7b96ac2013-03-20 12:49:49 -070061 gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 return 0;
63 }
64 return -EPERM;
65}
66
67static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
68{
69 int *fdp = (int*)CMSG_DATA(cmsg);
70 struct scm_fp_list *fpl = *fplp;
71 struct file **fpp;
72 int i, num;
73
74 num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
75
76 if (num <= 0)
77 return 0;
78
79 if (num > SCM_MAX_FD)
80 return -EINVAL;
81
82 if (!fpl)
83 {
84 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
85 if (!fpl)
86 return -ENOMEM;
87 *fplp = fpl;
88 fpl->count = 0;
Eric Dumazetbba14de2010-11-23 14:09:15 +000089 fpl->max = SCM_MAX_FD;
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 }
91 fpp = &fpl->fp[fpl->count];
92
Eric Dumazetbba14de2010-11-23 14:09:15 +000093 if (fpl->count + num > fpl->max)
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 return -EINVAL;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090095
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 /*
97 * Verify the descriptors and increment the usage count.
98 */
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090099
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 for (i=0; i< num; i++)
101 {
102 int fd = fdp[i];
103 struct file *file;
104
Al Viro326be7b2011-03-13 17:08:22 -0400105 if (fd < 0 || !(file = fget_raw(fd)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 return -EBADF;
107 *fpp++ = file;
108 fpl->count++;
109 }
110 return num;
111}
112
113void __scm_destroy(struct scm_cookie *scm)
114{
115 struct scm_fp_list *fpl = scm->fp;
116 int i;
117
118 if (fpl) {
119 scm->fp = NULL;
Al Viro6120d3d2012-06-24 10:03:05 +0400120 for (i=fpl->count-1; i>=0; i--)
121 fput(fpl->fp[i]);
122 kfree(fpl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 }
124}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000125EXPORT_SYMBOL(__scm_destroy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
127int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
128{
129 struct cmsghdr *cmsg;
130 int err;
131
132 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
133 {
134 err = -EINVAL;
135
136 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
137 /* The first check was omitted in <= 2.2.5. The reasoning was
138 that parser checks cmsg_len in any case, so that
139 additional check would be work duplication.
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900140 But if cmsg_level is not SOL_SOCKET, we do not check
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 for too short ancillary data object at all! Oops.
142 OK, let's add it...
143 */
144 if (!CMSG_OK(msg, cmsg))
145 goto error;
146
147 if (cmsg->cmsg_level != SOL_SOCKET)
148 continue;
149
150 switch (cmsg->cmsg_type)
151 {
152 case SCM_RIGHTS:
Eric W. Biederman76dadd762010-02-28 01:20:36 +0000153 if (!sock->ops || sock->ops->family != PF_UNIX)
154 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 err=scm_fp_copy(cmsg, &p->fp);
156 if (err<0)
157 goto error;
158 break;
159 case SCM_CREDENTIALS:
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600160 {
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000161 struct ucred creds;
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600162 kuid_t uid;
163 kgid_t gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
165 goto error;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000166 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
167 err = scm_check_creds(&creds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 if (err)
169 goto error;
Eric W. Biederman257b5352010-06-13 03:32:34 +0000170
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000171 p->creds.pid = creds.pid;
172 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
Eric W. Biederman257b5352010-06-13 03:32:34 +0000173 struct pid *pid;
174 err = -ESRCH;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000175 pid = find_get_pid(creds.pid);
Eric W. Biederman257b5352010-06-13 03:32:34 +0000176 if (!pid)
177 goto error;
178 put_pid(p->pid);
179 p->pid = pid;
180 }
181
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600182 err = -EINVAL;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000183 uid = make_kuid(current_user_ns(), creds.uid);
184 gid = make_kgid(current_user_ns(), creds.gid);
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600185 if (!uid_valid(uid) || !gid_valid(gid))
186 goto error;
187
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000188 p->creds.uid = uid;
189 p->creds.gid = gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 break;
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600191 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 default:
193 goto error;
194 }
195 }
196
197 if (p->fp && !p->fp->count)
198 {
199 kfree(p->fp);
200 p->fp = NULL;
201 }
202 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900203
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204error:
205 scm_destroy(p);
206 return err;
207}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000208EXPORT_SYMBOL(__scm_send);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209
210int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
211{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700212 struct cmsghdr __user *cm
213 = (__force struct cmsghdr __user *)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 struct cmsghdr cmhdr;
215 int cmlen = CMSG_LEN(len);
216 int err;
217
218 if (MSG_CMSG_COMPAT & msg->msg_flags)
219 return put_cmsg_compat(msg, level, type, len, data);
220
221 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
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 }
229 cmhdr.cmsg_level = level;
230 cmhdr.cmsg_type = type;
231 cmhdr.cmsg_len = cmlen;
232
233 err = -EFAULT;
234 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900235 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
237 goto out;
238 cmlen = CMSG_SPACE(len);
Wei Yongjun1ac70e72007-12-20 14:36:44 -0800239 if (msg->msg_controllen < cmlen)
240 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 msg->msg_control += cmlen;
242 msg->msg_controllen -= cmlen;
243 err = 0;
244out:
245 return err;
246}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000247EXPORT_SYMBOL(put_cmsg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248
249void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
250{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700251 struct cmsghdr __user *cm
252 = (__force struct cmsghdr __user*)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253
254 int fdmax = 0;
255 int fdnum = scm->fp->count;
256 struct file **fp = scm->fp->fp;
257 int __user *cmfptr;
258 int err = 0, i;
259
260 if (MSG_CMSG_COMPAT & msg->msg_flags) {
261 scm_detach_fds_compat(msg, scm);
262 return;
263 }
264
265 if (msg->msg_controllen > sizeof(struct cmsghdr))
266 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
267 / sizeof(int));
268
269 if (fdnum < fdmax)
270 fdmax = fdnum;
271
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700272 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
273 i++, cmfptr++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 {
John Fastabend48a87cc2012-08-14 12:34:30 +0000275 struct socket *sock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 int new_fd;
277 err = security_file_receive(fp[i]);
278 if (err)
279 break;
Ulrich Drepper4a195422007-07-15 23:40:34 -0700280 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
281 ? O_CLOEXEC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 if (err < 0)
283 break;
284 new_fd = err;
285 err = put_user(new_fd, cmfptr);
286 if (err) {
287 put_unused_fd(new_fd);
288 break;
289 }
290 /* Bump the usage count and install the file. */
John Fastabend48a87cc2012-08-14 12:34:30 +0000291 sock = sock_from_file(fp[i], &err);
Daniel Wagnerd8429502013-01-21 21:09:00 +0000292 if (sock) {
Zefan Li6ffd4642013-04-08 20:03:47 +0000293 sock_update_netprioidx(sock->sk);
Zefan Li211d2f972013-04-08 20:03:35 +0000294 sock_update_classid(sock->sk);
Daniel Wagnerd8429502013-01-21 21:09:00 +0000295 }
Al Virocb0942b2012-08-27 14:48:26 -0400296 fd_install(new_fd, get_file(fp[i]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 }
298
299 if (i > 0)
300 {
301 int cmlen = CMSG_LEN(i*sizeof(int));
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700302 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 if (!err)
304 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
305 if (!err)
306 err = put_user(cmlen, &cm->cmsg_len);
307 if (!err) {
308 cmlen = CMSG_SPACE(i*sizeof(int));
309 msg->msg_control += cmlen;
310 msg->msg_controllen -= cmlen;
311 }
312 }
313 if (i < fdnum || (fdnum && fdmax <= 0))
314 msg->msg_flags |= MSG_CTRUNC;
315
316 /*
317 * All of the files that fit in the message have had their
318 * usage counts incremented, so we just free the list.
319 */
320 __scm_destroy(scm);
321}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000322EXPORT_SYMBOL(scm_detach_fds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323
324struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
325{
326 struct scm_fp_list *new_fpl;
327 int i;
328
329 if (!fpl)
330 return NULL;
331
Eric Dumazetbba14de2010-11-23 14:09:15 +0000332 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
333 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 if (new_fpl) {
Eric Dumazetbba14de2010-11-23 14:09:15 +0000335 for (i = 0; i < fpl->count; i++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 get_file(fpl->fp[i]);
Eric Dumazetbba14de2010-11-23 14:09:15 +0000337 new_fpl->max = new_fpl->count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 }
339 return new_fpl;
340}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341EXPORT_SYMBOL(scm_fp_dup);