1 /* scm.c - Socket level control messages processing.
3 * Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
4 * Alignment and value checking mods by Craig Metz
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.
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>
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>
30 #include <asm/system.h>
31 #include <asm/uaccess.h>
33 #include <net/protocol.h>
34 #include <linux/skbuff.h>
36 #include <net/compat.h>
41 * Only allow a user to send credentials, that they could set with
45 static __inline__
int scm_check_creds(struct ucred
*creds
)
47 const struct cred
*cred
= current_cred();
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
))) {
59 static int scm_fp_copy(struct cmsghdr
*cmsg
, struct scm_fp_list
**fplp
)
61 int *fdp
= (int*)CMSG_DATA(cmsg
);
62 struct scm_fp_list
*fpl
= *fplp
;
66 num
= (cmsg
->cmsg_len
- CMSG_ALIGN(sizeof(struct cmsghdr
)))/sizeof(int);
76 fpl
= kmalloc(sizeof(struct scm_fp_list
), GFP_KERNEL
);
82 fpp
= &fpl
->fp
[fpl
->count
];
84 if (fpl
->count
+ num
> SCM_MAX_FD
)
88 * Verify the descriptors and increment the usage count.
91 for (i
=0; i
< num
; i
++)
96 if (fd
< 0 || !(file
= fget(fd
)))
104 void __scm_destroy(struct scm_cookie
*scm
)
106 struct scm_fp_list
*fpl
= scm
->fp
;
111 if (current
->scm_work_list
) {
112 list_add_tail(&fpl
->list
, current
->scm_work_list
);
114 LIST_HEAD(work_list
);
116 current
->scm_work_list
= &work_list
;
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
);
122 list_del(&fpl
->list
);
123 for (i
=fpl
->count
-1; i
>=0; i
--)
128 current
->scm_work_list
= NULL
;
133 int __scm_send(struct socket
*sock
, struct msghdr
*msg
, struct scm_cookie
*p
)
135 struct cmsghdr
*cmsg
;
138 for (cmsg
= CMSG_FIRSTHDR(msg
); cmsg
; cmsg
= CMSG_NXTHDR(msg
, cmsg
))
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.
150 if (!CMSG_OK(msg
, cmsg
))
153 if (cmsg
->cmsg_level
!= SOL_SOCKET
)
156 switch (cmsg
->cmsg_type
)
159 err
=scm_fp_copy(cmsg
, &p
->fp
);
163 case SCM_CREDENTIALS
:
164 if (cmsg
->cmsg_len
!= CMSG_LEN(sizeof(struct ucred
)))
166 memcpy(&p
->creds
, CMSG_DATA(cmsg
), sizeof(struct ucred
));
167 err
= scm_check_creds(&p
->creds
);
176 if (p
->fp
&& !p
->fp
->count
)
188 int put_cmsg(struct msghdr
* msg
, int level
, int type
, int len
, void *data
)
190 struct cmsghdr __user
*cm
191 = (__force
struct cmsghdr __user
*)msg
->msg_control
;
192 struct cmsghdr cmhdr
;
193 int cmlen
= CMSG_LEN(len
);
196 if (MSG_CMSG_COMPAT
& msg
->msg_flags
)
197 return put_cmsg_compat(msg
, level
, type
, len
, data
);
199 if (cm
==NULL
|| msg
->msg_controllen
< sizeof(*cm
)) {
200 msg
->msg_flags
|= MSG_CTRUNC
;
201 return 0; /* XXX: return error? check spec. */
203 if (msg
->msg_controllen
< cmlen
) {
204 msg
->msg_flags
|= MSG_CTRUNC
;
205 cmlen
= msg
->msg_controllen
;
207 cmhdr
.cmsg_level
= level
;
208 cmhdr
.cmsg_type
= type
;
209 cmhdr
.cmsg_len
= cmlen
;
212 if (copy_to_user(cm
, &cmhdr
, sizeof cmhdr
))
214 if (copy_to_user(CMSG_DATA(cm
), data
, cmlen
- sizeof(struct cmsghdr
)))
216 cmlen
= CMSG_SPACE(len
);
217 if (msg
->msg_controllen
< cmlen
)
218 cmlen
= msg
->msg_controllen
;
219 msg
->msg_control
+= cmlen
;
220 msg
->msg_controllen
-= cmlen
;
226 void scm_detach_fds(struct msghdr
*msg
, struct scm_cookie
*scm
)
228 struct cmsghdr __user
*cm
229 = (__force
struct cmsghdr __user
*)msg
->msg_control
;
232 int fdnum
= scm
->fp
->count
;
233 struct file
**fp
= scm
->fp
->fp
;
237 if (MSG_CMSG_COMPAT
& msg
->msg_flags
) {
238 scm_detach_fds_compat(msg
, scm
);
242 if (msg
->msg_controllen
> sizeof(struct cmsghdr
))
243 fdmax
= ((msg
->msg_controllen
- sizeof(struct cmsghdr
))
249 for (i
=0, cmfptr
=(__force
int __user
*)CMSG_DATA(cm
); i
<fdmax
;
253 err
= security_file_receive(fp
[i
]);
256 err
= get_unused_fd_flags(MSG_CMSG_CLOEXEC
& msg
->msg_flags
261 err
= put_user(new_fd
, cmfptr
);
263 put_unused_fd(new_fd
);
266 /* Bump the usage count and install the file. */
268 fd_install(new_fd
, fp
[i
]);
273 int cmlen
= CMSG_LEN(i
*sizeof(int));
274 err
= put_user(SOL_SOCKET
, &cm
->cmsg_level
);
276 err
= put_user(SCM_RIGHTS
, &cm
->cmsg_type
);
278 err
= put_user(cmlen
, &cm
->cmsg_len
);
280 cmlen
= CMSG_SPACE(i
*sizeof(int));
281 msg
->msg_control
+= cmlen
;
282 msg
->msg_controllen
-= cmlen
;
285 if (i
< fdnum
|| (fdnum
&& fdmax
<= 0))
286 msg
->msg_flags
|= MSG_CTRUNC
;
289 * All of the files that fit in the message have had their
290 * usage counts incremented, so we just free the list.
295 struct scm_fp_list
*scm_fp_dup(struct scm_fp_list
*fpl
)
297 struct scm_fp_list
*new_fpl
;
303 new_fpl
= kmalloc(sizeof(*fpl
), GFP_KERNEL
);
305 for (i
=fpl
->count
-1; i
>=0; i
--)
306 get_file(fpl
->fp
[i
]);
307 memcpy(new_fpl
, fpl
, sizeof(*fpl
));
312 EXPORT_SYMBOL(__scm_destroy
);
313 EXPORT_SYMBOL(__scm_send
);
314 EXPORT_SYMBOL(put_cmsg
);
315 EXPORT_SYMBOL(scm_detach_fds
);
316 EXPORT_SYMBOL(scm_fp_dup
);
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