blob: 8a1741b14302bd0cecdc265848feba8222400d17 [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>
Eric W. Biederman92f28d92013-03-15 01:03:33 -070027#include <linux/pid_namespace.h>
Pavel Emelyanovb4888932007-10-18 23:40:14 -070028#include <linux/pid.h>
29#include <linux/nsproxy.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090030#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#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>
Daniel Wagnerd8429502013-01-21 21:09:00 +000039#include <net/cls_cgroup.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
41
42/*
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090043 * Only allow a user to send credentials, that they could set with
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 * setu(g)id.
45 */
46
47static __inline__ int scm_check_creds(struct ucred *creds)
48{
David Howells86a264a2008-11-14 10:39:18 +110049 const struct cred *cred = current_cred();
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060050 kuid_t uid = make_kuid(cred->user_ns, creds->uid);
51 kgid_t gid = make_kgid(cred->user_ns, creds->gid);
52
53 if (!uid_valid(uid) || !gid_valid(gid))
54 return -EINVAL;
David Howellsb6dff3e2008-11-14 10:39:16 +110055
Eric W. Biederman92f28d92013-03-15 01:03:33 -070056 if ((creds->pid == task_tgid_vnr(current) ||
Andy Lutomirskid6616842013-08-22 11:39:15 -070057 ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060058 ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) ||
Eric W. Biedermanc7b96ac2013-03-20 12:49:49 -070059 uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -060060 ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) ||
Eric W. Biedermanc7b96ac2013-03-20 12:49:49 -070061 gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 return 0;
63 }
64 return -EPERM;
65}
66
67static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
68{
69 int *fdp = (int*)CMSG_DATA(cmsg);
70 struct scm_fp_list *fpl = *fplp;
71 struct file **fpp;
72 int i, num;
73
74 num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
75
76 if (num <= 0)
77 return 0;
78
79 if (num > SCM_MAX_FD)
80 return -EINVAL;
81
82 if (!fpl)
83 {
84 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
85 if (!fpl)
86 return -ENOMEM;
87 *fplp = fpl;
88 fpl->count = 0;
Eric Dumazetbba14de2010-11-23 14:09:15 +000089 fpl->max = SCM_MAX_FD;
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 }
91 fpp = &fpl->fp[fpl->count];
92
Eric Dumazetbba14de2010-11-23 14:09:15 +000093 if (fpl->count + num > fpl->max)
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 return -EINVAL;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090095
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 /*
97 * Verify the descriptors and increment the usage count.
98 */
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +090099
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 for (i=0; i< num; i++)
101 {
102 int fd = fdp[i];
103 struct file *file;
104
Al Viro326be7b2011-03-13 17:08:22 -0400105 if (fd < 0 || !(file = fget_raw(fd)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 return -EBADF;
107 *fpp++ = file;
108 fpl->count++;
109 }
110 return num;
111}
112
113void __scm_destroy(struct scm_cookie *scm)
114{
115 struct scm_fp_list *fpl = scm->fp;
116 int i;
117
118 if (fpl) {
119 scm->fp = NULL;
Al Viro6120d3d2012-06-24 10:03:05 +0400120 for (i=fpl->count-1; i>=0; i--)
121 fput(fpl->fp[i]);
122 kfree(fpl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 }
124}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000125EXPORT_SYMBOL(__scm_destroy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
127int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
128{
129 struct cmsghdr *cmsg;
130 int err;
131
Gu Zhengf95b4142014-12-11 11:22:04 +0800132 for_each_cmsghdr(cmsg, msg) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 err = -EINVAL;
134
135 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
136 /* The first check was omitted in <= 2.2.5. The reasoning was
137 that parser checks cmsg_len in any case, so that
138 additional check would be work duplication.
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900139 But if cmsg_level is not SOL_SOCKET, we do not check
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 for too short ancillary data object at all! Oops.
141 OK, let's add it...
142 */
143 if (!CMSG_OK(msg, cmsg))
144 goto error;
145
146 if (cmsg->cmsg_level != SOL_SOCKET)
147 continue;
148
149 switch (cmsg->cmsg_type)
150 {
151 case SCM_RIGHTS:
Eric W. Biederman76dadd762010-02-28 01:20:36 +0000152 if (!sock->ops || sock->ops->family != PF_UNIX)
153 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 err=scm_fp_copy(cmsg, &p->fp);
155 if (err<0)
156 goto error;
157 break;
158 case SCM_CREDENTIALS:
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600159 {
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000160 struct ucred creds;
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600161 kuid_t uid;
162 kgid_t gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
164 goto error;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000165 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
166 err = scm_check_creds(&creds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 if (err)
168 goto error;
Eric W. Biederman257b5352010-06-13 03:32:34 +0000169
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000170 p->creds.pid = creds.pid;
171 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
Eric W. Biederman257b5352010-06-13 03:32:34 +0000172 struct pid *pid;
173 err = -ESRCH;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000174 pid = find_get_pid(creds.pid);
Eric W. Biederman257b5352010-06-13 03:32:34 +0000175 if (!pid)
176 goto error;
177 put_pid(p->pid);
178 p->pid = pid;
179 }
180
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600181 err = -EINVAL;
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000182 uid = make_kuid(current_user_ns(), creds.uid);
183 gid = make_kgid(current_user_ns(), creds.gid);
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600184 if (!uid_valid(uid) || !gid_valid(gid))
185 goto error;
186
Eric W. Biedermandbe9a412012-09-06 18:20:01 +0000187 p->creds.uid = uid;
188 p->creds.gid = gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 break;
Eric W. Biedermanb2e4f542012-05-23 16:39:45 -0600190 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 default:
192 goto error;
193 }
194 }
195
196 if (p->fp && !p->fp->count)
197 {
198 kfree(p->fp);
199 p->fp = NULL;
200 }
201 return 0;
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900202
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203error:
204 scm_destroy(p);
205 return err;
206}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000207EXPORT_SYMBOL(__scm_send);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208
209int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
210{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700211 struct cmsghdr __user *cm
212 = (__force struct cmsghdr __user *)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 struct cmsghdr cmhdr;
214 int cmlen = CMSG_LEN(len);
215 int err;
216
217 if (MSG_CMSG_COMPAT & msg->msg_flags)
218 return put_cmsg_compat(msg, level, type, len, data);
219
220 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
221 msg->msg_flags |= MSG_CTRUNC;
222 return 0; /* XXX: return error? check spec. */
223 }
224 if (msg->msg_controllen < cmlen) {
225 msg->msg_flags |= MSG_CTRUNC;
226 cmlen = msg->msg_controllen;
227 }
228 cmhdr.cmsg_level = level;
229 cmhdr.cmsg_type = type;
230 cmhdr.cmsg_len = cmlen;
231
232 err = -EFAULT;
233 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
YOSHIFUJI Hideaki4ec93ed2007-02-09 23:24:36 +0900234 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
236 goto out;
237 cmlen = CMSG_SPACE(len);
Wei Yongjun1ac70e72007-12-20 14:36:44 -0800238 if (msg->msg_controllen < cmlen)
239 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 msg->msg_control += cmlen;
241 msg->msg_controllen -= cmlen;
242 err = 0;
243out:
244 return err;
245}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000246EXPORT_SYMBOL(put_cmsg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247
248void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
249{
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700250 struct cmsghdr __user *cm
251 = (__force struct cmsghdr __user*)msg->msg_control;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252
253 int fdmax = 0;
254 int fdnum = scm->fp->count;
255 struct file **fp = scm->fp->fp;
256 int __user *cmfptr;
257 int err = 0, i;
258
259 if (MSG_CMSG_COMPAT & msg->msg_flags) {
260 scm_detach_fds_compat(msg, scm);
261 return;
262 }
263
264 if (msg->msg_controllen > sizeof(struct cmsghdr))
265 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
266 / sizeof(int));
267
268 if (fdnum < fdmax)
269 fdmax = fdnum;
270
Stephen Hemmingercfcabdc2007-10-09 01:59:42 -0700271 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
272 i++, cmfptr++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 {
John Fastabend48a87cc2012-08-14 12:34:30 +0000274 struct socket *sock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 int new_fd;
276 err = security_file_receive(fp[i]);
277 if (err)
278 break;
Ulrich Drepper4a195422007-07-15 23:40:34 -0700279 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
280 ? O_CLOEXEC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 if (err < 0)
282 break;
283 new_fd = err;
284 err = put_user(new_fd, cmfptr);
285 if (err) {
286 put_unused_fd(new_fd);
287 break;
288 }
289 /* Bump the usage count and install the file. */
John Fastabend48a87cc2012-08-14 12:34:30 +0000290 sock = sock_from_file(fp[i], &err);
Daniel Wagnerd8429502013-01-21 21:09:00 +0000291 if (sock) {
Zefan Li6ffd4642013-04-08 20:03:47 +0000292 sock_update_netprioidx(sock->sk);
Zefan Li211d2f972013-04-08 20:03:35 +0000293 sock_update_classid(sock->sk);
Daniel Wagnerd8429502013-01-21 21:09:00 +0000294 }
Al Virocb0942b2012-08-27 14:48:26 -0400295 fd_install(new_fd, get_file(fp[i]));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 }
297
298 if (i > 0)
299 {
300 int cmlen = CMSG_LEN(i*sizeof(int));
Miklos Szeredieffee6a2006-10-09 21:42:14 -0700301 err = put_user(SOL_SOCKET, &cm->cmsg_level);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 if (!err)
303 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
304 if (!err)
305 err = put_user(cmlen, &cm->cmsg_len);
306 if (!err) {
307 cmlen = CMSG_SPACE(i*sizeof(int));
Daniel Borkmann69003172015-11-20 00:11:56 +0100308 if (msg->msg_controllen < cmlen)
309 cmlen = msg->msg_controllen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 msg->msg_control += cmlen;
311 msg->msg_controllen -= cmlen;
312 }
313 }
314 if (i < fdnum || (fdnum && fdmax <= 0))
315 msg->msg_flags |= MSG_CTRUNC;
316
317 /*
318 * All of the files that fit in the message have had their
319 * usage counts incremented, so we just free the list.
320 */
321 __scm_destroy(scm);
322}
Eric Dumazet9e34a5b2010-07-09 21:22:04 +0000323EXPORT_SYMBOL(scm_detach_fds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324
325struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
326{
327 struct scm_fp_list *new_fpl;
328 int i;
329
330 if (!fpl)
331 return NULL;
332
Eric Dumazetbba14de2010-11-23 14:09:15 +0000333 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
334 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 if (new_fpl) {
Eric Dumazetbba14de2010-11-23 14:09:15 +0000336 for (i = 0; i < fpl->count; i++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 get_file(fpl->fp[i]);
Eric Dumazetbba14de2010-11-23 14:09:15 +0000338 new_fpl->max = new_fpl->count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 }
340 return new_fpl;
341}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342EXPORT_SYMBOL(scm_fp_dup);