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