blob: 811b53fb330e8a40e640db483965acfc8c55cc4a [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
31#include <asm/system.h>
32#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>
39
40
41/*
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090042 * Only allow a user to send credentials, that they could set with
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 * setu(g)id.
44 */
45
46static __inline__ int scm_check_creds(struct ucred *creds)
47{
David Howells86a264a2008-11-14 10:39:18 +110048 const struct cred *cred = current_cred();
David Howellsb6dff3e2008-11-14 10:39:16 +110049
Pavel Emelyanovb4888932007-10-18 23:40:14 -070050 if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
David Howellsb6dff3e2008-11-14 10:39:16 +110051 ((creds->uid == cred->uid || creds->uid == cred->euid ||
52 creds->uid == cred->suid) || capable(CAP_SETUID)) &&
53 ((creds->gid == cred->gid || creds->gid == cred->egid ||
54 creds->gid == cred->sgid) || capable(CAP_SETGID))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 return 0;
56 }
57 return -EPERM;
58}
59
60static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
61{
62 int *fdp = (int*)CMSG_DATA(cmsg);
63 struct scm_fp_list *fpl = *fplp;
64 struct file **fpp;
65 int i, num;
66
67 num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
68
69 if (num <= 0)
70 return 0;
71
72 if (num > SCM_MAX_FD)
73 return -EINVAL;
74
75 if (!fpl)
76 {
77 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
78 if (!fpl)
79 return -ENOMEM;
80 *fplp = fpl;
81 fpl->count = 0;
Eric Dumazetbba14de2010-11-23 14:09:15 +000082 fpl->max = SCM_MAX_FD;
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 }
84 fpp = &fpl->fp[fpl->count];
85
Eric Dumazetbba14de2010-11-23 14:09:15 +000086 if (fpl->count + num > fpl->max)
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 return -EINVAL;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090088
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 /*
90 * Verify the descriptors and increment the usage count.
91 */
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090092
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 for (i=0; i< num; i++)
94 {
95 int fd = fdp[i];
96 struct file *file;
97
Al Viro326be7b2011-03-13 17:08:22 -040098 if (fd < 0 || !(file = fget_raw(fd)))
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 return -EBADF;
100 *fpp++ = file;
101 fpl->count++;
102 }
103 return num;
104}
105
106void __scm_destroy(struct scm_cookie *scm)
107{
108 struct scm_fp_list *fpl = scm->fp;
109 int i;
110
111 if (fpl) {
112 scm->fp = NULL;
David Millerf8d570a2008-11-06 00:37:40 -0800113 if (current->scm_work_list) {
114 list_add_tail(&fpl->list, current->scm_work_list);
115 } else {
116 LIST_HEAD(work_list);
117
118 current->scm_work_list = &work_list;
119
120 list_add(&fpl->list, &work_list);
121 while (!list_empty(&work_list)) {
122 fpl = list_first_entry(&work_list, struct scm_fp_list, list);
123
124 list_del(&fpl->list);
125 for (i=fpl->count-1; i>=0; i--)
126 fput(fpl->fp[i]);
127 kfree(fpl);
128 }
129
130 current->scm_work_list = NULL;
131 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 }
133}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000134EXPORT_SYMBOL(__scm_destroy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135
136int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
137{
138 struct cmsghdr *cmsg;
139 int err;
140
141 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
142 {
143 err = -EINVAL;
144
145 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
146 /* The first check was omitted in <= 2.2.5. The reasoning was
147 that parser checks cmsg_len in any case, so that
148 additional check would be work duplication.
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900149 But if cmsg_level is not SOL_SOCKET, we do not check
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 for too short ancillary data object at all! Oops.
151 OK, let's add it...
152 */
153 if (!CMSG_OK(msg, cmsg))
154 goto error;
155
156 if (cmsg->cmsg_level != SOL_SOCKET)
157 continue;
158
159 switch (cmsg->cmsg_type)
160 {
161 case SCM_RIGHTS:
Eric W. Biederman76dadd72010-02-28 01:20:36 +0000162 if (!sock->ops || sock->ops->family != PF_UNIX)
163 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 err=scm_fp_copy(cmsg, &p->fp);
165 if (err<0)
166 goto error;
167 break;
168 case SCM_CREDENTIALS:
169 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
170 goto error;
171 memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
172 err = scm_check_creds(&p->creds);
173 if (err)
174 goto error;
Eric W. Biederman257b5352010-06-13 03:32:34 +0000175
176 if (pid_vnr(p->pid) != p->creds.pid) {
177 struct pid *pid;
178 err = -ESRCH;
179 pid = find_get_pid(p->creds.pid);
180 if (!pid)
181 goto error;
182 put_pid(p->pid);
183 p->pid = pid;
184 }
185
186 if ((p->cred->euid != p->creds.uid) ||
187 (p->cred->egid != p->creds.gid)) {
188 struct cred *cred;
189 err = -ENOMEM;
190 cred = prepare_creds();
191 if (!cred)
192 goto error;
193
194 cred->uid = cred->euid = p->creds.uid;
Tim Chen265d5c22011-08-09 06:48:32 +0000195 cred->gid = cred->egid = p->creds.gid;
Eric W. Biederman257b5352010-06-13 03:32:34 +0000196 put_cred(p->cred);
197 p->cred = cred;
198 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 break;
200 default:
201 goto error;
202 }
203 }
204
205 if (p->fp && !p->fp->count)
206 {
207 kfree(p->fp);
208 p->fp = NULL;
209 }
210 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900211
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212error:
213 scm_destroy(p);
214 return err;
215}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000216EXPORT_SYMBOL(__scm_send);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217
218int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
219{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700220 struct cmsghdr __user *cm
221 = (__force struct cmsghdr __user *)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 struct cmsghdr cmhdr;
223 int cmlen = CMSG_LEN(len);
224 int err;
225
226 if (MSG_CMSG_COMPAT & msg->msg_flags)
227 return put_cmsg_compat(msg, level, type, len, data);
228
229 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
230 msg->msg_flags |= MSG_CTRUNC;
231 return 0; /* XXX: return error? check spec. */
232 }
233 if (msg->msg_controllen < cmlen) {
234 msg->msg_flags |= MSG_CTRUNC;
235 cmlen = msg->msg_controllen;
236 }
237 cmhdr.cmsg_level = level;
238 cmhdr.cmsg_type = type;
239 cmhdr.cmsg_len = cmlen;
240
241 err = -EFAULT;
242 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900243 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
245 goto out;
246 cmlen = CMSG_SPACE(len);
Wei Yongjun1ac70e72007-12-20 14:36:44 -0800247 if (msg->msg_controllen < cmlen)
248 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 msg->msg_control += cmlen;
250 msg->msg_controllen -= cmlen;
251 err = 0;
252out:
253 return err;
254}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000255EXPORT_SYMBOL(put_cmsg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256
257void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
258{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700259 struct cmsghdr __user *cm
260 = (__force struct cmsghdr __user*)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
262 int fdmax = 0;
263 int fdnum = scm->fp->count;
264 struct file **fp = scm->fp->fp;
265 int __user *cmfptr;
266 int err = 0, i;
267
268 if (MSG_CMSG_COMPAT & msg->msg_flags) {
269 scm_detach_fds_compat(msg, scm);
270 return;
271 }
272
273 if (msg->msg_controllen > sizeof(struct cmsghdr))
274 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
275 / sizeof(int));
276
277 if (fdnum < fdmax)
278 fdmax = fdnum;
279
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700280 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
281 i++, cmfptr++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 {
283 int new_fd;
284 err = security_file_receive(fp[i]);
285 if (err)
286 break;
Ulrich Drepper4a195422007-07-15 23:40:34 -0700287 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
288 ? O_CLOEXEC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 if (err < 0)
290 break;
291 new_fd = err;
292 err = put_user(new_fd, cmfptr);
293 if (err) {
294 put_unused_fd(new_fd);
295 break;
296 }
297 /* Bump the usage count and install the file. */
298 get_file(fp[i]);
299 fd_install(new_fd, fp[i]);
300 }
301
302 if (i > 0)
303 {
304 int cmlen = CMSG_LEN(i*sizeof(int));
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700305 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 if (!err)
307 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
308 if (!err)
309 err = put_user(cmlen, &cm->cmsg_len);
310 if (!err) {
311 cmlen = CMSG_SPACE(i*sizeof(int));
312 msg->msg_control += cmlen;
313 msg->msg_controllen -= cmlen;
314 }
315 }
316 if (i < fdnum || (fdnum && fdmax <= 0))
317 msg->msg_flags |= MSG_CTRUNC;
318
319 /*
320 * All of the files that fit in the message have had their
321 * usage counts incremented, so we just free the list.
322 */
323 __scm_destroy(scm);
324}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000325EXPORT_SYMBOL(scm_detach_fds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326
327struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
328{
329 struct scm_fp_list *new_fpl;
330 int i;
331
332 if (!fpl)
333 return NULL;
334
Eric Dumazetbba14de2010-11-23 14:09:15 +0000335 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
336 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 if (new_fpl) {
Eric Dumazetbba14de2010-11-23 14:09:15 +0000338 for (i = 0; i < fpl->count; i++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 get_file(fpl->fp[i]);
Eric Dumazetbba14de2010-11-23 14:09:15 +0000340 new_fpl->max = new_fpl->count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 }
342 return new_fpl;
343}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344EXPORT_SYMBOL(scm_fp_dup);