blob: ff52ad0a51501c98891401d6e29f18dfab80ade9 [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
Eric Dumazet16e57262011-09-19 05:52:27 +0000176 if (!p->pid || pid_vnr(p->pid) != p->creds.pid) {
Eric W. Biederman257b5352010-06-13 03:32:34 +0000177 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
Eric Dumazet16e57262011-09-19 05:52:27 +0000186 if (!p->cred ||
187 (p->cred->euid != p->creds.uid) ||
188 (p->cred->egid != p->creds.gid)) {
Eric W. Biederman257b5352010-06-13 03:32:34 +0000189 struct cred *cred;
190 err = -ENOMEM;
191 cred = prepare_creds();
192 if (!cred)
193 goto error;
194
195 cred->uid = cred->euid = p->creds.uid;
Tim Chene33f7a92011-08-09 06:48:32 +0000196 cred->gid = cred->egid = p->creds.gid;
Eric Dumazet16e57262011-09-19 05:52:27 +0000197 if (p->cred)
198 put_cred(p->cred);
Eric W. Biederman257b5352010-06-13 03:32:34 +0000199 p->cred = cred;
200 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 break;
202 default:
203 goto error;
204 }
205 }
206
207 if (p->fp && !p->fp->count)
208 {
209 kfree(p->fp);
210 p->fp = NULL;
211 }
212 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900213
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214error:
215 scm_destroy(p);
216 return err;
217}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000218EXPORT_SYMBOL(__scm_send);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219
220int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
221{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700222 struct cmsghdr __user *cm
223 = (__force struct cmsghdr __user *)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 struct cmsghdr cmhdr;
225 int cmlen = CMSG_LEN(len);
226 int err;
227
228 if (MSG_CMSG_COMPAT & msg->msg_flags)
229 return put_cmsg_compat(msg, level, type, len, data);
230
231 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
232 msg->msg_flags |= MSG_CTRUNC;
233 return 0; /* XXX: return error? check spec. */
234 }
235 if (msg->msg_controllen < cmlen) {
236 msg->msg_flags |= MSG_CTRUNC;
237 cmlen = msg->msg_controllen;
238 }
239 cmhdr.cmsg_level = level;
240 cmhdr.cmsg_type = type;
241 cmhdr.cmsg_len = cmlen;
242
243 err = -EFAULT;
244 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900245 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
247 goto out;
248 cmlen = CMSG_SPACE(len);
Wei Yongjun1ac70e72007-12-20 14:36:44 -0800249 if (msg->msg_controllen < cmlen)
250 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 msg->msg_control += cmlen;
252 msg->msg_controllen -= cmlen;
253 err = 0;
254out:
255 return err;
256}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000257EXPORT_SYMBOL(put_cmsg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
259void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
260{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700261 struct cmsghdr __user *cm
262 = (__force struct cmsghdr __user*)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
264 int fdmax = 0;
265 int fdnum = scm->fp->count;
266 struct file **fp = scm->fp->fp;
267 int __user *cmfptr;
268 int err = 0, i;
269
270 if (MSG_CMSG_COMPAT & msg->msg_flags) {
271 scm_detach_fds_compat(msg, scm);
272 return;
273 }
274
275 if (msg->msg_controllen > sizeof(struct cmsghdr))
276 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
277 / sizeof(int));
278
279 if (fdnum < fdmax)
280 fdmax = fdnum;
281
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700282 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
283 i++, cmfptr++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 {
285 int new_fd;
286 err = security_file_receive(fp[i]);
287 if (err)
288 break;
Ulrich Drepper4a195422007-07-15 23:40:34 -0700289 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
290 ? O_CLOEXEC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 if (err < 0)
292 break;
293 new_fd = err;
294 err = put_user(new_fd, cmfptr);
295 if (err) {
296 put_unused_fd(new_fd);
297 break;
298 }
299 /* Bump the usage count and install the file. */
300 get_file(fp[i]);
301 fd_install(new_fd, fp[i]);
302 }
303
304 if (i > 0)
305 {
306 int cmlen = CMSG_LEN(i*sizeof(int));
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700307 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 if (!err)
309 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
310 if (!err)
311 err = put_user(cmlen, &cm->cmsg_len);
312 if (!err) {
313 cmlen = CMSG_SPACE(i*sizeof(int));
314 msg->msg_control += cmlen;
315 msg->msg_controllen -= cmlen;
316 }
317 }
318 if (i < fdnum || (fdnum && fdmax <= 0))
319 msg->msg_flags |= MSG_CTRUNC;
320
321 /*
322 * All of the files that fit in the message have had their
323 * usage counts incremented, so we just free the list.
324 */
325 __scm_destroy(scm);
326}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000327EXPORT_SYMBOL(scm_detach_fds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328
329struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
330{
331 struct scm_fp_list *new_fpl;
332 int i;
333
334 if (!fpl)
335 return NULL;
336
Eric Dumazetbba14de2010-11-23 14:09:15 +0000337 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
338 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 if (new_fpl) {
Eric Dumazetbba14de2010-11-23 14:09:15 +0000340 for (i = 0; i < fpl->count; i++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 get_file(fpl->fp[i]);
Eric Dumazetbba14de2010-11-23 14:09:15 +0000342 new_fpl->max = new_fpl->count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 }
344 return new_fpl;
345}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346EXPORT_SYMBOL(scm_fp_dup);