[PATCH] kill gratitious includes of major.h under net/*
[linux-3.10.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/errno.h>
15 #include <linux/sched.h>
16 #include <linux/mm.h>
17 #include <linux/kernel.h>
18 #include <linux/stat.h>
19 #include <linux/socket.h>
20 #include <linux/file.h>
21 #include <linux/fcntl.h>
22 #include <linux/net.h>
23 #include <linux/interrupt.h>
24 #include <linux/netdevice.h>
25 #include <linux/security.h>
26
27 #include <asm/system.h>
28 #include <asm/uaccess.h>
29
30 #include <net/protocol.h>
31 #include <linux/skbuff.h>
32 #include <net/sock.h>
33 #include <net/compat.h>
34 #include <net/scm.h>
35
36
37 /*
38  *      Only allow a user to send credentials, that they could set with 
39  *      setu(g)id.
40  */
41
42 static __inline__ int scm_check_creds(struct ucred *creds)
43 {
44         if ((creds->pid == current->tgid || capable(CAP_SYS_ADMIN)) &&
45             ((creds->uid == current->uid || creds->uid == current->euid ||
46               creds->uid == current->suid) || capable(CAP_SETUID)) &&
47             ((creds->gid == current->gid || creds->gid == current->egid ||
48               creds->gid == current->sgid) || capable(CAP_SETGID))) {
49                return 0;
50         }
51         return -EPERM;
52 }
53
54 static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
55 {
56         int *fdp = (int*)CMSG_DATA(cmsg);
57         struct scm_fp_list *fpl = *fplp;
58         struct file **fpp;
59         int i, num;
60
61         num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
62
63         if (num <= 0)
64                 return 0;
65
66         if (num > SCM_MAX_FD)
67                 return -EINVAL;
68
69         if (!fpl)
70         {
71                 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
72                 if (!fpl)
73                         return -ENOMEM;
74                 *fplp = fpl;
75                 fpl->count = 0;
76         }
77         fpp = &fpl->fp[fpl->count];
78
79         if (fpl->count + num > SCM_MAX_FD)
80                 return -EINVAL;
81         
82         /*
83          *      Verify the descriptors and increment the usage count.
84          */
85          
86         for (i=0; i< num; i++)
87         {
88                 int fd = fdp[i];
89                 struct file *file;
90
91                 if (fd < 0 || !(file = fget(fd)))
92                         return -EBADF;
93                 *fpp++ = file;
94                 fpl->count++;
95         }
96         return num;
97 }
98
99 void __scm_destroy(struct scm_cookie *scm)
100 {
101         struct scm_fp_list *fpl = scm->fp;
102         int i;
103
104         if (fpl) {
105                 scm->fp = NULL;
106                 for (i=fpl->count-1; i>=0; i--)
107                         fput(fpl->fp[i]);
108                 kfree(fpl);
109         }
110 }
111
112 int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
113 {
114         struct cmsghdr *cmsg;
115         int err;
116
117         for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
118         {
119                 err = -EINVAL;
120
121                 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
122                 /* The first check was omitted in <= 2.2.5. The reasoning was
123                    that parser checks cmsg_len in any case, so that
124                    additional check would be work duplication.
125                    But if cmsg_level is not SOL_SOCKET, we do not check 
126                    for too short ancillary data object at all! Oops.
127                    OK, let's add it...
128                  */
129                 if (!CMSG_OK(msg, cmsg))
130                         goto error;
131
132                 if (cmsg->cmsg_level != SOL_SOCKET)
133                         continue;
134
135                 switch (cmsg->cmsg_type)
136                 {
137                 case SCM_RIGHTS:
138                         err=scm_fp_copy(cmsg, &p->fp);
139                         if (err<0)
140                                 goto error;
141                         break;
142                 case SCM_CREDENTIALS:
143                         if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
144                                 goto error;
145                         memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
146                         err = scm_check_creds(&p->creds);
147                         if (err)
148                                 goto error;
149                         break;
150                 default:
151                         goto error;
152                 }
153         }
154
155         if (p->fp && !p->fp->count)
156         {
157                 kfree(p->fp);
158                 p->fp = NULL;
159         }
160         return 0;
161         
162 error:
163         scm_destroy(p);
164         return err;
165 }
166
167 int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
168 {
169         struct cmsghdr __user *cm = (struct cmsghdr __user *)msg->msg_control;
170         struct cmsghdr cmhdr;
171         int cmlen = CMSG_LEN(len);
172         int err;
173
174         if (MSG_CMSG_COMPAT & msg->msg_flags)
175                 return put_cmsg_compat(msg, level, type, len, data);
176
177         if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
178                 msg->msg_flags |= MSG_CTRUNC;
179                 return 0; /* XXX: return error? check spec. */
180         }
181         if (msg->msg_controllen < cmlen) {
182                 msg->msg_flags |= MSG_CTRUNC;
183                 cmlen = msg->msg_controllen;
184         }
185         cmhdr.cmsg_level = level;
186         cmhdr.cmsg_type = type;
187         cmhdr.cmsg_len = cmlen;
188
189         err = -EFAULT;
190         if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
191                 goto out; 
192         if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
193                 goto out;
194         cmlen = CMSG_SPACE(len);
195         msg->msg_control += cmlen;
196         msg->msg_controllen -= cmlen;
197         err = 0;
198 out:
199         return err;
200 }
201
202 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
203 {
204         struct cmsghdr __user *cm = (struct cmsghdr __user*)msg->msg_control;
205
206         int fdmax = 0;
207         int fdnum = scm->fp->count;
208         struct file **fp = scm->fp->fp;
209         int __user *cmfptr;
210         int err = 0, i;
211
212         if (MSG_CMSG_COMPAT & msg->msg_flags) {
213                 scm_detach_fds_compat(msg, scm);
214                 return;
215         }
216
217         if (msg->msg_controllen > sizeof(struct cmsghdr))
218                 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
219                          / sizeof(int));
220
221         if (fdnum < fdmax)
222                 fdmax = fdnum;
223
224         for (i=0, cmfptr=(int __user *)CMSG_DATA(cm); i<fdmax; i++, cmfptr++)
225         {
226                 int new_fd;
227                 err = security_file_receive(fp[i]);
228                 if (err)
229                         break;
230                 err = get_unused_fd();
231                 if (err < 0)
232                         break;
233                 new_fd = err;
234                 err = put_user(new_fd, cmfptr);
235                 if (err) {
236                         put_unused_fd(new_fd);
237                         break;
238                 }
239                 /* Bump the usage count and install the file. */
240                 get_file(fp[i]);
241                 fd_install(new_fd, fp[i]);
242         }
243
244         if (i > 0)
245         {
246                 int cmlen = CMSG_LEN(i*sizeof(int));
247                 if (!err)
248                         err = put_user(SOL_SOCKET, &cm->cmsg_level);
249                 if (!err)
250                         err = put_user(SCM_RIGHTS, &cm->cmsg_type);
251                 if (!err)
252                         err = put_user(cmlen, &cm->cmsg_len);
253                 if (!err) {
254                         cmlen = CMSG_SPACE(i*sizeof(int));
255                         msg->msg_control += cmlen;
256                         msg->msg_controllen -= cmlen;
257                 }
258         }
259         if (i < fdnum || (fdnum && fdmax <= 0))
260                 msg->msg_flags |= MSG_CTRUNC;
261
262         /*
263          * All of the files that fit in the message have had their
264          * usage counts incremented, so we just free the list.
265          */
266         __scm_destroy(scm);
267 }
268
269 struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
270 {
271         struct scm_fp_list *new_fpl;
272         int i;
273
274         if (!fpl)
275                 return NULL;
276
277         new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
278         if (new_fpl) {
279                 for (i=fpl->count-1; i>=0; i--)
280                         get_file(fpl->fp[i]);
281                 memcpy(new_fpl, fpl, sizeof(*fpl));
282         }
283         return new_fpl;
284 }
285
286 EXPORT_SYMBOL(__scm_destroy);
287 EXPORT_SYMBOL(__scm_send);
288 EXPORT_SYMBOL(put_cmsg);
289 EXPORT_SYMBOL(scm_detach_fds);
290 EXPORT_SYMBOL(scm_fp_dup);