blob: ab242cc1accaae7673b76784aa5838a76d9b10c4 [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;
David Millerf8d570a2008-11-06 00:37:40 -080078 INIT_LIST_HEAD(&fpl->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 fpl->count = 0;
80 }
81 fpp = &fpl->fp[fpl->count];
82
83 if (fpl->count + num > SCM_MAX_FD)
84 return -EINVAL;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090085
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 /*
87 * Verify the descriptors and increment the usage count.
88 */
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090089
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 for (i=0; i< num; i++)
91 {
92 int fd = fdp[i];
93 struct file *file;
94
95 if (fd < 0 || !(file = fget(fd)))
96 return -EBADF;
97 *fpp++ = file;
98 fpl->count++;
99 }
100 return num;
101}
102
103void __scm_destroy(struct scm_cookie *scm)
104{
105 struct scm_fp_list *fpl = scm->fp;
106 int i;
107
108 if (fpl) {
109 scm->fp = NULL;
David Millerf8d570a2008-11-06 00:37:40 -0800110 if (current->scm_work_list) {
111 list_add_tail(&fpl->list, current->scm_work_list);
112 } else {
113 LIST_HEAD(work_list);
114
115 current->scm_work_list = &work_list;
116
117 list_add(&fpl->list, &work_list);
118 while (!list_empty(&work_list)) {
119 fpl = list_first_entry(&work_list, struct scm_fp_list, list);
120
121 list_del(&fpl->list);
122 for (i=fpl->count-1; i>=0; i--)
123 fput(fpl->fp[i]);
124 kfree(fpl);
125 }
126
127 current->scm_work_list = NULL;
128 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 }
130}
131
132int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
133{
134 struct cmsghdr *cmsg;
135 int err;
136
137 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
138 {
139 err = -EINVAL;
140
141 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
142 /* The first check was omitted in <= 2.2.5. The reasoning was
143 that parser checks cmsg_len in any case, so that
144 additional check would be work duplication.
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900145 But if cmsg_level is not SOL_SOCKET, we do not check
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 for too short ancillary data object at all! Oops.
147 OK, let's add it...
148 */
149 if (!CMSG_OK(msg, cmsg))
150 goto error;
151
152 if (cmsg->cmsg_level != SOL_SOCKET)
153 continue;
154
155 switch (cmsg->cmsg_type)
156 {
157 case SCM_RIGHTS:
158 err=scm_fp_copy(cmsg, &p->fp);
159 if (err<0)
160 goto error;
161 break;
162 case SCM_CREDENTIALS:
163 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
164 goto error;
165 memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
166 err = scm_check_creds(&p->creds);
167 if (err)
168 goto error;
169 break;
170 default:
171 goto error;
172 }
173 }
174
175 if (p->fp && !p->fp->count)
176 {
177 kfree(p->fp);
178 p->fp = NULL;
179 }
180 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900181
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182error:
183 scm_destroy(p);
184 return err;
185}
186
187int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
188{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700189 struct cmsghdr __user *cm
190 = (__force struct cmsghdr __user *)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 struct cmsghdr cmhdr;
192 int cmlen = CMSG_LEN(len);
193 int err;
194
195 if (MSG_CMSG_COMPAT & msg->msg_flags)
196 return put_cmsg_compat(msg, level, type, len, data);
197
198 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
199 msg->msg_flags |= MSG_CTRUNC;
200 return 0; /* XXX: return error? check spec. */
201 }
202 if (msg->msg_controllen < cmlen) {
203 msg->msg_flags |= MSG_CTRUNC;
204 cmlen = msg->msg_controllen;
205 }
206 cmhdr.cmsg_level = level;
207 cmhdr.cmsg_type = type;
208 cmhdr.cmsg_len = cmlen;
209
210 err = -EFAULT;
211 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900212 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
214 goto out;
215 cmlen = CMSG_SPACE(len);
Wei Yongjun1ac70e72007-12-20 14:36:44 -0800216 if (msg->msg_controllen < cmlen)
217 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 msg->msg_control += cmlen;
219 msg->msg_controllen -= cmlen;
220 err = 0;
221out:
222 return err;
223}
224
225void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
226{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700227 struct cmsghdr __user *cm
228 = (__force struct cmsghdr __user*)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
230 int fdmax = 0;
231 int fdnum = scm->fp->count;
232 struct file **fp = scm->fp->fp;
233 int __user *cmfptr;
234 int err = 0, i;
235
236 if (MSG_CMSG_COMPAT & msg->msg_flags) {
237 scm_detach_fds_compat(msg, scm);
238 return;
239 }
240
241 if (msg->msg_controllen > sizeof(struct cmsghdr))
242 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
243 / sizeof(int));
244
245 if (fdnum < fdmax)
246 fdmax = fdnum;
247
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700248 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
249 i++, cmfptr++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 {
251 int new_fd;
252 err = security_file_receive(fp[i]);
253 if (err)
254 break;
Ulrich Drepper4a195422007-07-15 23:40:34 -0700255 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
256 ? O_CLOEXEC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 if (err < 0)
258 break;
259 new_fd = err;
260 err = put_user(new_fd, cmfptr);
261 if (err) {
262 put_unused_fd(new_fd);
263 break;
264 }
265 /* Bump the usage count and install the file. */
266 get_file(fp[i]);
267 fd_install(new_fd, fp[i]);
268 }
269
270 if (i > 0)
271 {
272 int cmlen = CMSG_LEN(i*sizeof(int));
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700273 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 if (!err)
275 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
276 if (!err)
277 err = put_user(cmlen, &cm->cmsg_len);
278 if (!err) {
279 cmlen = CMSG_SPACE(i*sizeof(int));
280 msg->msg_control += cmlen;
281 msg->msg_controllen -= cmlen;
282 }
283 }
284 if (i < fdnum || (fdnum && fdmax <= 0))
285 msg->msg_flags |= MSG_CTRUNC;
286
287 /*
288 * All of the files that fit in the message have had their
289 * usage counts incremented, so we just free the list.
290 */
291 __scm_destroy(scm);
292}
293
294struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
295{
296 struct scm_fp_list *new_fpl;
297 int i;
298
299 if (!fpl)
300 return NULL;
301
302 new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
303 if (new_fpl) {
David Millerf8d570a2008-11-06 00:37:40 -0800304 INIT_LIST_HEAD(&new_fpl->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 for (i=fpl->count-1; i>=0; i--)
306 get_file(fpl->fp[i]);
307 memcpy(new_fpl, fpl, sizeof(*fpl));
308 }
309 return new_fpl;
310}
311
312EXPORT_SYMBOL(__scm_destroy);
313EXPORT_SYMBOL(__scm_send);
314EXPORT_SYMBOL(put_cmsg);
315EXPORT_SYMBOL(scm_detach_fds);
316EXPORT_SYMBOL(scm_fp_dup);