blob: 413cab89017d0818c997b8d6a807997fa47c92d0 [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;
82 }
83 fpp = &fpl->fp[fpl->count];
84
85 if (fpl->count + num > SCM_MAX_FD)
86 return -EINVAL;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090087
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 /*
89 * Verify the descriptors and increment the usage count.
90 */
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090091
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 for (i=0; i< num; i++)
93 {
94 int fd = fdp[i];
95 struct file *file;
96
97 if (fd < 0 || !(file = fget(fd)))
98 return -EBADF;
99 *fpp++ = file;
100 fpl->count++;
101 }
102 return num;
103}
104
105void __scm_destroy(struct scm_cookie *scm)
106{
107 struct scm_fp_list *fpl = scm->fp;
108 int i;
109
110 if (fpl) {
111 scm->fp = NULL;
David Millerf8d570a2008-11-06 00:37:40 -0800112 if (current->scm_work_list) {
113 list_add_tail(&fpl->list, current->scm_work_list);
114 } else {
115 LIST_HEAD(work_list);
116
117 current->scm_work_list = &work_list;
118
119 list_add(&fpl->list, &work_list);
120 while (!list_empty(&work_list)) {
121 fpl = list_first_entry(&work_list, struct scm_fp_list, list);
122
123 list_del(&fpl->list);
124 for (i=fpl->count-1; i>=0; i--)
125 fput(fpl->fp[i]);
126 kfree(fpl);
127 }
128
129 current->scm_work_list = NULL;
130 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 }
132}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000133EXPORT_SYMBOL(__scm_destroy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
135int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
136{
137 struct cmsghdr *cmsg;
138 int err;
139
140 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
141 {
142 err = -EINVAL;
143
144 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
145 /* The first check was omitted in <= 2.2.5. The reasoning was
146 that parser checks cmsg_len in any case, so that
147 additional check would be work duplication.
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900148 But if cmsg_level is not SOL_SOCKET, we do not check
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 for too short ancillary data object at all! Oops.
150 OK, let's add it...
151 */
152 if (!CMSG_OK(msg, cmsg))
153 goto error;
154
155 if (cmsg->cmsg_level != SOL_SOCKET)
156 continue;
157
158 switch (cmsg->cmsg_type)
159 {
160 case SCM_RIGHTS:
Eric W. Biederman76dadd762010-02-28 01:20:36 +0000161 if (!sock->ops || sock->ops->family != PF_UNIX)
162 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 err=scm_fp_copy(cmsg, &p->fp);
164 if (err<0)
165 goto error;
166 break;
167 case SCM_CREDENTIALS:
168 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
169 goto error;
170 memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
171 err = scm_check_creds(&p->creds);
172 if (err)
173 goto error;
Eric W. Biederman257b5352010-06-13 03:32:34 +0000174
175 if (pid_vnr(p->pid) != p->creds.pid) {
176 struct pid *pid;
177 err = -ESRCH;
178 pid = find_get_pid(p->creds.pid);
179 if (!pid)
180 goto error;
181 put_pid(p->pid);
182 p->pid = pid;
183 }
184
185 if ((p->cred->euid != p->creds.uid) ||
186 (p->cred->egid != p->creds.gid)) {
187 struct cred *cred;
188 err = -ENOMEM;
189 cred = prepare_creds();
190 if (!cred)
191 goto error;
192
193 cred->uid = cred->euid = p->creds.uid;
194 cred->gid = cred->egid = p->creds.uid;
195 put_cred(p->cred);
196 p->cred = cred;
197 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 break;
199 default:
200 goto error;
201 }
202 }
203
204 if (p->fp && !p->fp->count)
205 {
206 kfree(p->fp);
207 p->fp = NULL;
208 }
209 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900210
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211error:
212 scm_destroy(p);
213 return err;
214}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000215EXPORT_SYMBOL(__scm_send);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
217int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
218{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700219 struct cmsghdr __user *cm
220 = (__force struct cmsghdr __user *)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 struct cmsghdr cmhdr;
222 int cmlen = CMSG_LEN(len);
223 int err;
224
225 if (MSG_CMSG_COMPAT & msg->msg_flags)
226 return put_cmsg_compat(msg, level, type, len, data);
227
228 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
229 msg->msg_flags |= MSG_CTRUNC;
230 return 0; /* XXX: return error? check spec. */
231 }
232 if (msg->msg_controllen < cmlen) {
233 msg->msg_flags |= MSG_CTRUNC;
234 cmlen = msg->msg_controllen;
235 }
236 cmhdr.cmsg_level = level;
237 cmhdr.cmsg_type = type;
238 cmhdr.cmsg_len = cmlen;
239
240 err = -EFAULT;
241 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900242 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
244 goto out;
245 cmlen = CMSG_SPACE(len);
Wei Yongjun1ac70e72007-12-20 14:36:44 -0800246 if (msg->msg_controllen < cmlen)
247 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 msg->msg_control += cmlen;
249 msg->msg_controllen -= cmlen;
250 err = 0;
251out:
252 return err;
253}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000254EXPORT_SYMBOL(put_cmsg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255
256void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
257{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700258 struct cmsghdr __user *cm
259 = (__force struct cmsghdr __user*)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260
261 int fdmax = 0;
262 int fdnum = scm->fp->count;
263 struct file **fp = scm->fp->fp;
264 int __user *cmfptr;
265 int err = 0, i;
266
267 if (MSG_CMSG_COMPAT & msg->msg_flags) {
268 scm_detach_fds_compat(msg, scm);
269 return;
270 }
271
272 if (msg->msg_controllen > sizeof(struct cmsghdr))
273 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
274 / sizeof(int));
275
276 if (fdnum < fdmax)
277 fdmax = fdnum;
278
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700279 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
280 i++, cmfptr++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 {
282 int new_fd;
283 err = security_file_receive(fp[i]);
284 if (err)
285 break;
Ulrich Drepper4a195422007-07-15 23:40:34 -0700286 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
287 ? O_CLOEXEC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 if (err < 0)
289 break;
290 new_fd = err;
291 err = put_user(new_fd, cmfptr);
292 if (err) {
293 put_unused_fd(new_fd);
294 break;
295 }
296 /* Bump the usage count and install the file. */
297 get_file(fp[i]);
298 fd_install(new_fd, fp[i]);
299 }
300
301 if (i > 0)
302 {
303 int cmlen = CMSG_LEN(i*sizeof(int));
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700304 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 if (!err)
306 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
307 if (!err)
308 err = put_user(cmlen, &cm->cmsg_len);
309 if (!err) {
310 cmlen = CMSG_SPACE(i*sizeof(int));
311 msg->msg_control += cmlen;
312 msg->msg_controllen -= cmlen;
313 }
314 }
315 if (i < fdnum || (fdnum && fdmax <= 0))
316 msg->msg_flags |= MSG_CTRUNC;
317
318 /*
319 * All of the files that fit in the message have had their
320 * usage counts incremented, so we just free the list.
321 */
322 __scm_destroy(scm);
323}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000324EXPORT_SYMBOL(scm_detach_fds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325
326struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
327{
328 struct scm_fp_list *new_fpl;
329 int i;
330
331 if (!fpl)
332 return NULL;
333
334 new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
335 if (new_fpl) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 for (i=fpl->count-1; i>=0; i--)
337 get_file(fpl->fp[i]);
338 memcpy(new_fpl, fpl, sizeof(*fpl));
339 }
340 return new_fpl;
341}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342EXPORT_SYMBOL(scm_fp_dup);