blob: b12303dd39d9c68df84271963c2b9132fab7b035 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
30#include <asm/system.h>
31#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{
Pavel Emelyanovb4888932007-10-18 23:40:14 -070047 if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 ((creds->uid == current->uid || creds->uid == current->euid ||
49 creds->uid == current->suid) || capable(CAP_SETUID)) &&
50 ((creds->gid == current->gid || creds->gid == current->egid ||
51 creds->gid == current->sgid) || capable(CAP_SETGID))) {
52 return 0;
53 }
54 return -EPERM;
55}
56
57static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
58{
59 int *fdp = (int*)CMSG_DATA(cmsg);
60 struct scm_fp_list *fpl = *fplp;
61 struct file **fpp;
62 int i, num;
63
64 num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
65
66 if (num <= 0)
67 return 0;
68
69 if (num > SCM_MAX_FD)
70 return -EINVAL;
71
72 if (!fpl)
73 {
74 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
75 if (!fpl)
76 return -ENOMEM;
77 *fplp = fpl;
78 fpl->count = 0;
79 }
80 fpp = &fpl->fp[fpl->count];
81
82 if (fpl->count + num > SCM_MAX_FD)
83 return -EINVAL;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090084
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 /*
86 * Verify the descriptors and increment the usage count.
87 */
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090088
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 for (i=0; i< num; i++)
90 {
91 int fd = fdp[i];
92 struct file *file;
93
94 if (fd < 0 || !(file = fget(fd)))
95 return -EBADF;
96 *fpp++ = file;
97 fpl->count++;
98 }
99 return num;
100}
101
102void __scm_destroy(struct scm_cookie *scm)
103{
104 struct scm_fp_list *fpl = scm->fp;
105 int i;
106
107 if (fpl) {
108 scm->fp = NULL;
David Millerf8d570a2008-11-06 00:37:40 -0800109 if (current->scm_work_list) {
110 list_add_tail(&fpl->list, current->scm_work_list);
111 } else {
112 LIST_HEAD(work_list);
113
114 current->scm_work_list = &work_list;
115
116 list_add(&fpl->list, &work_list);
117 while (!list_empty(&work_list)) {
118 fpl = list_first_entry(&work_list, struct scm_fp_list, list);
119
120 list_del(&fpl->list);
121 for (i=fpl->count-1; i>=0; i--)
122 fput(fpl->fp[i]);
123 kfree(fpl);
124 }
125
126 current->scm_work_list = NULL;
127 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 }
129}
130
131int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
132{
133 struct cmsghdr *cmsg;
134 int err;
135
136 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
137 {
138 err = -EINVAL;
139
140 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
141 /* The first check was omitted in <= 2.2.5. The reasoning was
142 that parser checks cmsg_len in any case, so that
143 additional check would be work duplication.
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900144 But if cmsg_level is not SOL_SOCKET, we do not check
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 for too short ancillary data object at all! Oops.
146 OK, let's add it...
147 */
148 if (!CMSG_OK(msg, cmsg))
149 goto error;
150
151 if (cmsg->cmsg_level != SOL_SOCKET)
152 continue;
153
154 switch (cmsg->cmsg_type)
155 {
156 case SCM_RIGHTS:
157 err=scm_fp_copy(cmsg, &p->fp);
158 if (err<0)
159 goto error;
160 break;
161 case SCM_CREDENTIALS:
162 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
163 goto error;
164 memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
165 err = scm_check_creds(&p->creds);
166 if (err)
167 goto error;
168 break;
169 default:
170 goto error;
171 }
172 }
173
174 if (p->fp && !p->fp->count)
175 {
176 kfree(p->fp);
177 p->fp = NULL;
178 }
179 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900180
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181error:
182 scm_destroy(p);
183 return err;
184}
185
186int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
187{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700188 struct cmsghdr __user *cm
189 = (__force struct cmsghdr __user *)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 struct cmsghdr cmhdr;
191 int cmlen = CMSG_LEN(len);
192 int err;
193
194 if (MSG_CMSG_COMPAT & msg->msg_flags)
195 return put_cmsg_compat(msg, level, type, len, data);
196
197 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
198 msg->msg_flags |= MSG_CTRUNC;
199 return 0; /* XXX: return error? check spec. */
200 }
201 if (msg->msg_controllen < cmlen) {
202 msg->msg_flags |= MSG_CTRUNC;
203 cmlen = msg->msg_controllen;
204 }
205 cmhdr.cmsg_level = level;
206 cmhdr.cmsg_type = type;
207 cmhdr.cmsg_len = cmlen;
208
209 err = -EFAULT;
210 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900211 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
213 goto out;
214 cmlen = CMSG_SPACE(len);
Wei Yongjun1ac70e72007-12-20 14:36:44 -0800215 if (msg->msg_controllen < cmlen)
216 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 msg->msg_control += cmlen;
218 msg->msg_controllen -= cmlen;
219 err = 0;
220out:
221 return err;
222}
223
224void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
225{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700226 struct cmsghdr __user *cm
227 = (__force struct cmsghdr __user*)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228
229 int fdmax = 0;
230 int fdnum = scm->fp->count;
231 struct file **fp = scm->fp->fp;
232 int __user *cmfptr;
233 int err = 0, i;
234
235 if (MSG_CMSG_COMPAT & msg->msg_flags) {
236 scm_detach_fds_compat(msg, scm);
237 return;
238 }
239
240 if (msg->msg_controllen > sizeof(struct cmsghdr))
241 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
242 / sizeof(int));
243
244 if (fdnum < fdmax)
245 fdmax = fdnum;
246
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700247 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
248 i++, cmfptr++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 {
250 int new_fd;
251 err = security_file_receive(fp[i]);
252 if (err)
253 break;
Ulrich Drepper4a195422007-07-15 23:40:34 -0700254 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
255 ? O_CLOEXEC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 if (err < 0)
257 break;
258 new_fd = err;
259 err = put_user(new_fd, cmfptr);
260 if (err) {
261 put_unused_fd(new_fd);
262 break;
263 }
264 /* Bump the usage count and install the file. */
265 get_file(fp[i]);
266 fd_install(new_fd, fp[i]);
267 }
268
269 if (i > 0)
270 {
271 int cmlen = CMSG_LEN(i*sizeof(int));
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700272 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 if (!err)
274 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
275 if (!err)
276 err = put_user(cmlen, &cm->cmsg_len);
277 if (!err) {
278 cmlen = CMSG_SPACE(i*sizeof(int));
279 msg->msg_control += cmlen;
280 msg->msg_controllen -= cmlen;
281 }
282 }
283 if (i < fdnum || (fdnum && fdmax <= 0))
284 msg->msg_flags |= MSG_CTRUNC;
285
286 /*
287 * All of the files that fit in the message have had their
288 * usage counts incremented, so we just free the list.
289 */
290 __scm_destroy(scm);
291}
292
293struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
294{
295 struct scm_fp_list *new_fpl;
296 int i;
297
298 if (!fpl)
299 return NULL;
300
301 new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
302 if (new_fpl) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 for (i=fpl->count-1; i>=0; i--)
304 get_file(fpl->fp[i]);
305 memcpy(new_fpl, fpl, sizeof(*fpl));
306 }
307 return new_fpl;
308}
309
310EXPORT_SYMBOL(__scm_destroy);
311EXPORT_SYMBOL(__scm_send);
312EXPORT_SYMBOL(put_cmsg);
313EXPORT_SYMBOL(scm_detach_fds);
314EXPORT_SYMBOL(scm_fp_dup);