Merge branch 'drbd-8.4_ed6' into for-3.8-drivers-drbd-8.4_ed6
[deliverable/linux.git] / net / core / scm.c
CommitLineData
1da177e4
LT
1/* 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>
4fc268d2 14#include <linux/capability.h>
1da177e4
LT
15#include <linux/errno.h>
16#include <linux/sched.h>
17#include <linux/mm.h>
18#include <linux/kernel.h>
1da177e4
LT
19#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>
b488893a
PE
27#include <linux/pid.h>
28#include <linux/nsproxy.h>
5a0e3ad6 29#include <linux/slab.h>
1da177e4 30
1da177e4
LT
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/*
4ec93edb 41 * Only allow a user to send credentials, that they could set with
1da177e4
LT
42 * setu(g)id.
43 */
44
45static __inline__ int scm_check_creds(struct ucred *creds)
46{
86a264ab 47 const struct cred *cred = current_cred();
b2e4f544
EB
48 kuid_t uid = make_kuid(cred->user_ns, creds->uid);
49 kgid_t gid = make_kgid(cred->user_ns, creds->gid);
50
51 if (!uid_valid(uid) || !gid_valid(gid))
52 return -EINVAL;
b6dff3ec 53
b488893a 54 if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
b2e4f544
EB
55 ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) ||
56 uid_eq(uid, cred->suid)) || capable(CAP_SETUID)) &&
57 ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) ||
58 gid_eq(gid, cred->sgid)) || capable(CAP_SETGID))) {
1da177e4
LT
59 return 0;
60 }
61 return -EPERM;
62}
63
64static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
65{
66 int *fdp = (int*)CMSG_DATA(cmsg);
67 struct scm_fp_list *fpl = *fplp;
68 struct file **fpp;
69 int i, num;
70
71 num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
72
73 if (num <= 0)
74 return 0;
75
76 if (num > SCM_MAX_FD)
77 return -EINVAL;
78
79 if (!fpl)
80 {
81 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
82 if (!fpl)
83 return -ENOMEM;
84 *fplp = fpl;
85 fpl->count = 0;
bba14de9 86 fpl->max = SCM_MAX_FD;
1da177e4
LT
87 }
88 fpp = &fpl->fp[fpl->count];
89
bba14de9 90 if (fpl->count + num > fpl->max)
1da177e4 91 return -EINVAL;
4ec93edb 92
1da177e4
LT
93 /*
94 * Verify the descriptors and increment the usage count.
95 */
4ec93edb 96
1da177e4
LT
97 for (i=0; i< num; i++)
98 {
99 int fd = fdp[i];
100 struct file *file;
101
326be7b4 102 if (fd < 0 || !(file = fget_raw(fd)))
1da177e4
LT
103 return -EBADF;
104 *fpp++ = file;
105 fpl->count++;
106 }
107 return num;
108}
109
110void __scm_destroy(struct scm_cookie *scm)
111{
112 struct scm_fp_list *fpl = scm->fp;
113 int i;
114
115 if (fpl) {
116 scm->fp = NULL;
6120d3db
AV
117 for (i=fpl->count-1; i>=0; i--)
118 fput(fpl->fp[i]);
119 kfree(fpl);
1da177e4
LT
120 }
121}
9e34a5b5 122EXPORT_SYMBOL(__scm_destroy);
1da177e4
LT
123
124int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
125{
126 struct cmsghdr *cmsg;
127 int err;
128
129 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
130 {
131 err = -EINVAL;
132
133 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
134 /* The first check was omitted in <= 2.2.5. The reasoning was
135 that parser checks cmsg_len in any case, so that
136 additional check would be work duplication.
4ec93edb 137 But if cmsg_level is not SOL_SOCKET, we do not check
1da177e4
LT
138 for too short ancillary data object at all! Oops.
139 OK, let's add it...
140 */
141 if (!CMSG_OK(msg, cmsg))
142 goto error;
143
144 if (cmsg->cmsg_level != SOL_SOCKET)
145 continue;
146
147 switch (cmsg->cmsg_type)
148 {
149 case SCM_RIGHTS:
76dadd76
EB
150 if (!sock->ops || sock->ops->family != PF_UNIX)
151 goto error;
1da177e4
LT
152 err=scm_fp_copy(cmsg, &p->fp);
153 if (err<0)
154 goto error;
155 break;
156 case SCM_CREDENTIALS:
b2e4f544 157 {
dbe9a417 158 struct ucred creds;
b2e4f544
EB
159 kuid_t uid;
160 kgid_t gid;
1da177e4
LT
161 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
162 goto error;
dbe9a417
EB
163 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
164 err = scm_check_creds(&creds);
1da177e4
LT
165 if (err)
166 goto error;
257b5358 167
dbe9a417
EB
168 p->creds.pid = creds.pid;
169 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
257b5358
EB
170 struct pid *pid;
171 err = -ESRCH;
dbe9a417 172 pid = find_get_pid(creds.pid);
257b5358
EB
173 if (!pid)
174 goto error;
175 put_pid(p->pid);
176 p->pid = pid;
177 }
178
b2e4f544 179 err = -EINVAL;
dbe9a417
EB
180 uid = make_kuid(current_user_ns(), creds.uid);
181 gid = make_kgid(current_user_ns(), creds.gid);
b2e4f544
EB
182 if (!uid_valid(uid) || !gid_valid(gid))
183 goto error;
184
dbe9a417
EB
185 p->creds.uid = uid;
186 p->creds.gid = gid;
187
16e57262 188 if (!p->cred ||
b2e4f544
EB
189 !uid_eq(p->cred->euid, uid) ||
190 !gid_eq(p->cred->egid, gid)) {
257b5358
EB
191 struct cred *cred;
192 err = -ENOMEM;
193 cred = prepare_creds();
194 if (!cred)
195 goto error;
196
b2e4f544
EB
197 cred->uid = cred->euid = uid;
198 cred->gid = cred->egid = gid;
16e57262
ED
199 if (p->cred)
200 put_cred(p->cred);
257b5358
EB
201 p->cred = cred;
202 }
1da177e4 203 break;
b2e4f544 204 }
1da177e4
LT
205 default:
206 goto error;
207 }
208 }
209
210 if (p->fp && !p->fp->count)
211 {
212 kfree(p->fp);
213 p->fp = NULL;
214 }
215 return 0;
4ec93edb 216
1da177e4
LT
217error:
218 scm_destroy(p);
219 return err;
220}
9e34a5b5 221EXPORT_SYMBOL(__scm_send);
1da177e4
LT
222
223int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
224{
cfcabdcc
SH
225 struct cmsghdr __user *cm
226 = (__force struct cmsghdr __user *)msg->msg_control;
1da177e4
LT
227 struct cmsghdr cmhdr;
228 int cmlen = CMSG_LEN(len);
229 int err;
230
231 if (MSG_CMSG_COMPAT & msg->msg_flags)
232 return put_cmsg_compat(msg, level, type, len, data);
233
234 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
235 msg->msg_flags |= MSG_CTRUNC;
236 return 0; /* XXX: return error? check spec. */
237 }
238 if (msg->msg_controllen < cmlen) {
239 msg->msg_flags |= MSG_CTRUNC;
240 cmlen = msg->msg_controllen;
241 }
242 cmhdr.cmsg_level = level;
243 cmhdr.cmsg_type = type;
244 cmhdr.cmsg_len = cmlen;
245
246 err = -EFAULT;
247 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
4ec93edb 248 goto out;
1da177e4
LT
249 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
250 goto out;
251 cmlen = CMSG_SPACE(len);
1ac70e7a
WY
252 if (msg->msg_controllen < cmlen)
253 cmlen = msg->msg_controllen;
1da177e4
LT
254 msg->msg_control += cmlen;
255 msg->msg_controllen -= cmlen;
256 err = 0;
257out:
258 return err;
259}
9e34a5b5 260EXPORT_SYMBOL(put_cmsg);
1da177e4
LT
261
262void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
263{
cfcabdcc
SH
264 struct cmsghdr __user *cm
265 = (__force struct cmsghdr __user*)msg->msg_control;
1da177e4
LT
266
267 int fdmax = 0;
268 int fdnum = scm->fp->count;
269 struct file **fp = scm->fp->fp;
270 int __user *cmfptr;
271 int err = 0, i;
272
273 if (MSG_CMSG_COMPAT & msg->msg_flags) {
274 scm_detach_fds_compat(msg, scm);
275 return;
276 }
277
278 if (msg->msg_controllen > sizeof(struct cmsghdr))
279 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
280 / sizeof(int));
281
282 if (fdnum < fdmax)
283 fdmax = fdnum;
284
cfcabdcc
SH
285 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
286 i++, cmfptr++)
1da177e4 287 {
48a87cc2 288 struct socket *sock;
1da177e4
LT
289 int new_fd;
290 err = security_file_receive(fp[i]);
291 if (err)
292 break;
4a19542e
UD
293 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
294 ? O_CLOEXEC : 0);
1da177e4
LT
295 if (err < 0)
296 break;
297 new_fd = err;
298 err = put_user(new_fd, cmfptr);
299 if (err) {
300 put_unused_fd(new_fd);
301 break;
302 }
303 /* Bump the usage count and install the file. */
48a87cc2
JF
304 sock = sock_from_file(fp[i], &err);
305 if (sock)
306 sock_update_netprioidx(sock->sk, current);
cb0942b8 307 fd_install(new_fd, get_file(fp[i]));
1da177e4
LT
308 }
309
310 if (i > 0)
311 {
312 int cmlen = CMSG_LEN(i*sizeof(int));
effee6a0 313 err = put_user(SOL_SOCKET, &cm->cmsg_level);
1da177e4
LT
314 if (!err)
315 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
316 if (!err)
317 err = put_user(cmlen, &cm->cmsg_len);
318 if (!err) {
319 cmlen = CMSG_SPACE(i*sizeof(int));
320 msg->msg_control += cmlen;
321 msg->msg_controllen -= cmlen;
322 }
323 }
324 if (i < fdnum || (fdnum && fdmax <= 0))
325 msg->msg_flags |= MSG_CTRUNC;
326
327 /*
328 * All of the files that fit in the message have had their
329 * usage counts incremented, so we just free the list.
330 */
331 __scm_destroy(scm);
332}
9e34a5b5 333EXPORT_SYMBOL(scm_detach_fds);
1da177e4
LT
334
335struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
336{
337 struct scm_fp_list *new_fpl;
338 int i;
339
340 if (!fpl)
341 return NULL;
342
bba14de9
ED
343 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
344 GFP_KERNEL);
1da177e4 345 if (new_fpl) {
bba14de9 346 for (i = 0; i < fpl->count; i++)
1da177e4 347 get_file(fpl->fp[i]);
bba14de9 348 new_fpl->max = new_fpl->count;
1da177e4
LT
349 }
350 return new_fpl;
351}
1da177e4 352EXPORT_SYMBOL(scm_fp_dup);
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