blob: 57fb1ee6649f65a0994d86c6f8763fe6e14ba081 [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>
Pavel Emelyanovb4888932007-10-18 23:40:14 -070027#include <linux/pid.h>
28#include <linux/nsproxy.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090029#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <asm/uaccess.h>
32
33#include <net/protocol.h>
34#include <linux/skbuff.h>
35#include <net/sock.h>
36#include <net/compat.h>
37#include <net/scm.h>
38
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. Biederman00f70de2012-11-16 03:03:03 +000054 if ((creds->pid == task_tgid_vnr(current) || nsown_capable(CAP_SYS_ADMIN)) &&
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060055 ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) ||
Eric W. Biederman00f70de2012-11-16 03:03:03 +000056 uid_eq(uid, cred->suid)) || nsown_capable(CAP_SETUID)) &&
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060057 ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) ||
Eric W. Biederman00f70de2012-11-16 03:03:03 +000058 gid_eq(gid, cred->sgid)) || nsown_capable(CAP_SETGID))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 return 0;
60 }
61 return -EPERM;
62}
63
64static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
65{
66 int *fdp = (int*)CMSG_DATA(cmsg);
67 struct scm_fp_list *fpl = *fplp;
68 struct file **fpp;
69 int i, num;
70
71 num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
72
73 if (num <= 0)
74 return 0;
75
76 if (num > SCM_MAX_FD)
77 return -EINVAL;
78
79 if (!fpl)
80 {
81 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
82 if (!fpl)
83 return -ENOMEM;
84 *fplp = fpl;
85 fpl->count = 0;
Eric Dumazetbba14de2010-11-23 14:09:15 +000086 fpl->max = SCM_MAX_FD;
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 }
88 fpp = &fpl->fp[fpl->count];
89
Eric Dumazetbba14de2010-11-23 14:09:15 +000090 if (fpl->count + num > fpl->max)
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 return -EINVAL;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090092
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 /*
94 * Verify the descriptors and increment the usage count.
95 */
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090096
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 for (i=0; i< num; i++)
98 {
99 int fd = fdp[i];
100 struct file *file;
101
Al Viro326be7b2011-03-13 17:08:22 -0400102 if (fd < 0 || !(file = fget_raw(fd)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 return -EBADF;
104 *fpp++ = file;
105 fpl->count++;
106 }
107 return num;
108}
109
110void __scm_destroy(struct scm_cookie *scm)
111{
112 struct scm_fp_list *fpl = scm->fp;
113 int i;
114
115 if (fpl) {
116 scm->fp = NULL;
Al Viro6120d3d2012-06-24 10:03:05 +0400117 for (i=fpl->count-1; i>=0; i--)
118 fput(fpl->fp[i]);
119 kfree(fpl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 }
121}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000122EXPORT_SYMBOL(__scm_destroy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123
124int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
125{
126 struct cmsghdr *cmsg;
127 int err;
128
129 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
130 {
131 err = -EINVAL;
132
133 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
134 /* The first check was omitted in <= 2.2.5. The reasoning was
135 that parser checks cmsg_len in any case, so that
136 additional check would be work duplication.
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900137 But if cmsg_level is not SOL_SOCKET, we do not check
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 for too short ancillary data object at all! Oops.
139 OK, let's add it...
140 */
141 if (!CMSG_OK(msg, cmsg))
142 goto error;
143
144 if (cmsg->cmsg_level != SOL_SOCKET)
145 continue;
146
147 switch (cmsg->cmsg_type)
148 {
149 case SCM_RIGHTS:
Eric W. Biederman76dadd762010-02-28 01:20:36 +0000150 if (!sock->ops || sock->ops->family != PF_UNIX)
151 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 err=scm_fp_copy(cmsg, &p->fp);
153 if (err<0)
154 goto error;
155 break;
156 case SCM_CREDENTIALS:
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600157 {
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000158 struct ucred creds;
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600159 kuid_t uid;
160 kgid_t gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
162 goto error;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000163 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
164 err = scm_check_creds(&creds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 if (err)
166 goto error;
Eric W. Biederman257b5352010-06-13 03:32:34 +0000167
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000168 p->creds.pid = creds.pid;
169 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
Eric W. Biederman257b5352010-06-13 03:32:34 +0000170 struct pid *pid;
171 err = -ESRCH;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000172 pid = find_get_pid(creds.pid);
Eric W. Biederman257b5352010-06-13 03:32:34 +0000173 if (!pid)
174 goto error;
175 put_pid(p->pid);
176 p->pid = pid;
177 }
178
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600179 err = -EINVAL;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000180 uid = make_kuid(current_user_ns(), creds.uid);
181 gid = make_kgid(current_user_ns(), creds.gid);
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600182 if (!uid_valid(uid) || !gid_valid(gid))
183 goto error;
184
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000185 p->creds.uid = uid;
186 p->creds.gid = gid;
187
Eric Dumazet16e57262011-09-19 05:52:27 +0000188 if (!p->cred ||
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600189 !uid_eq(p->cred->euid, uid) ||
190 !gid_eq(p->cred->egid, gid)) {
Eric W. Biederman257b5352010-06-13 03:32:34 +0000191 struct cred *cred;
192 err = -ENOMEM;
193 cred = prepare_creds();
194 if (!cred)
195 goto error;
196
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600197 cred->uid = cred->euid = uid;
198 cred->gid = cred->egid = gid;
Eric Dumazet16e57262011-09-19 05:52:27 +0000199 if (p->cred)
200 put_cred(p->cred);
Eric W. Biederman257b5352010-06-13 03:32:34 +0000201 p->cred = cred;
202 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 break;
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600204 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 default:
206 goto error;
207 }
208 }
209
210 if (p->fp && !p->fp->count)
211 {
212 kfree(p->fp);
213 p->fp = NULL;
214 }
215 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217error:
218 scm_destroy(p);
219 return err;
220}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000221EXPORT_SYMBOL(__scm_send);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222
223int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
224{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700225 struct cmsghdr __user *cm
226 = (__force struct cmsghdr __user *)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 struct cmsghdr cmhdr;
228 int cmlen = CMSG_LEN(len);
229 int err;
230
231 if (MSG_CMSG_COMPAT & msg->msg_flags)
232 return put_cmsg_compat(msg, level, type, len, data);
233
234 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
235 msg->msg_flags |= MSG_CTRUNC;
236 return 0; /* XXX: return error? check spec. */
237 }
238 if (msg->msg_controllen < cmlen) {
239 msg->msg_flags |= MSG_CTRUNC;
240 cmlen = msg->msg_controllen;
241 }
242 cmhdr.cmsg_level = level;
243 cmhdr.cmsg_type = type;
244 cmhdr.cmsg_len = cmlen;
245
246 err = -EFAULT;
247 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900248 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
250 goto out;
251 cmlen = CMSG_SPACE(len);
Wei Yongjun1ac70e72007-12-20 14:36:44 -0800252 if (msg->msg_controllen < cmlen)
253 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 msg->msg_control += cmlen;
255 msg->msg_controllen -= cmlen;
256 err = 0;
257out:
258 return err;
259}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000260EXPORT_SYMBOL(put_cmsg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
262void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
263{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700264 struct cmsghdr __user *cm
265 = (__force struct cmsghdr __user*)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266
267 int fdmax = 0;
268 int fdnum = scm->fp->count;
269 struct file **fp = scm->fp->fp;
270 int __user *cmfptr;
271 int err = 0, i;
272
273 if (MSG_CMSG_COMPAT & msg->msg_flags) {
274 scm_detach_fds_compat(msg, scm);
275 return;
276 }
277
278 if (msg->msg_controllen > sizeof(struct cmsghdr))
279 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
280 / sizeof(int));
281
282 if (fdnum < fdmax)
283 fdmax = fdnum;
284
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700285 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
286 i++, cmfptr++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 {
John Fastabend48a87cc2012-08-14 12:34:30 +0000288 struct socket *sock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 int new_fd;
290 err = security_file_receive(fp[i]);
291 if (err)
292 break;
Ulrich Drepper4a195422007-07-15 23:40:34 -0700293 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
294 ? O_CLOEXEC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 if (err < 0)
296 break;
297 new_fd = err;
298 err = put_user(new_fd, cmfptr);
299 if (err) {
300 put_unused_fd(new_fd);
301 break;
302 }
303 /* Bump the usage count and install the file. */
John Fastabend48a87cc2012-08-14 12:34:30 +0000304 sock = sock_from_file(fp[i], &err);
305 if (sock)
306 sock_update_netprioidx(sock->sk, current);
Al Virocb0942b2012-08-27 14:48:26 -0400307 fd_install(new_fd, get_file(fp[i]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 }
309
310 if (i > 0)
311 {
312 int cmlen = CMSG_LEN(i*sizeof(int));
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700313 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 if (!err)
315 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
316 if (!err)
317 err = put_user(cmlen, &cm->cmsg_len);
318 if (!err) {
319 cmlen = CMSG_SPACE(i*sizeof(int));
320 msg->msg_control += cmlen;
321 msg->msg_controllen -= cmlen;
322 }
323 }
324 if (i < fdnum || (fdnum && fdmax <= 0))
325 msg->msg_flags |= MSG_CTRUNC;
326
327 /*
328 * All of the files that fit in the message have had their
329 * usage counts incremented, so we just free the list.
330 */
331 __scm_destroy(scm);
332}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000333EXPORT_SYMBOL(scm_detach_fds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
335struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
336{
337 struct scm_fp_list *new_fpl;
338 int i;
339
340 if (!fpl)
341 return NULL;
342
Eric Dumazetbba14de2010-11-23 14:09:15 +0000343 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
344 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 if (new_fpl) {
Eric Dumazetbba14de2010-11-23 14:09:15 +0000346 for (i = 0; i < fpl->count; i++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 get_file(fpl->fp[i]);
Eric Dumazetbba14de2010-11-23 14:09:15 +0000348 new_fpl->max = new_fpl->count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 }
350 return new_fpl;
351}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352EXPORT_SYMBOL(scm_fp_dup);