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>
29 #include <linux/slab.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();
48 kuid_t uid = make_kuid(cred->user_ns, creds->uid);
49 kgid_t gid = make_kgid(cred->user_ns, creds->gid);
51 if (!uid_valid(uid) || !gid_valid(gid))
54 if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
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))) {
64 static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
66 int *fdp = (int*)CMSG_DATA(cmsg);
67 struct scm_fp_list *fpl = *fplp;
71 num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
81 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
86 fpl->max = SCM_MAX_FD;
88 fpp = &fpl->fp[fpl->count];
90 if (fpl->count + num > fpl->max)
94 * Verify the descriptors and increment the usage count.
97 for (i=0; i< num; i++)
102 if (fd < 0 || !(file = fget_raw(fd)))
110 void __scm_destroy(struct scm_cookie *scm)
112 struct scm_fp_list *fpl = scm->fp;
117 for (i=fpl->count-1; i>=0; i--)
122 EXPORT_SYMBOL(__scm_destroy);
124 int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
126 struct cmsghdr *cmsg;
129 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
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.
137 But if cmsg_level is not SOL_SOCKET, we do not check
138 for too short ancillary data object at all! Oops.
141 if (!CMSG_OK(msg, cmsg))
144 if (cmsg->cmsg_level != SOL_SOCKET)
147 switch (cmsg->cmsg_type)
150 if (!sock->ops || sock->ops->family != PF_UNIX)
152 err=scm_fp_copy(cmsg, &p->fp);
156 case SCM_CREDENTIALS:
160 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
162 memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
163 err = scm_check_creds(&p->creds);
167 if (!p->pid || pid_vnr(p->pid) != p->creds.pid) {
170 pid = find_get_pid(p->creds.pid);
178 uid = make_kuid(current_user_ns(), p->creds.uid);
179 gid = make_kgid(current_user_ns(), p->creds.gid);
180 if (!uid_valid(uid) || !gid_valid(gid))
184 !uid_eq(p->cred->euid, uid) ||
185 !gid_eq(p->cred->egid, gid)) {
188 cred = prepare_creds();
192 cred->uid = cred->euid = uid;
193 cred->gid = cred->egid = gid;
205 if (p->fp && !p->fp->count)
216 EXPORT_SYMBOL(__scm_send);
218 int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
220 struct cmsghdr __user *cm
221 = (__force struct cmsghdr __user *)msg->msg_control;
222 struct cmsghdr cmhdr;
223 int cmlen = CMSG_LEN(len);
226 if (MSG_CMSG_COMPAT & msg->msg_flags)
227 return put_cmsg_compat(msg, level, type, len, data);
229 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
230 msg->msg_flags |= MSG_CTRUNC;
231 return 0; /* XXX: return error? check spec. */
233 if (msg->msg_controllen < cmlen) {
234 msg->msg_flags |= MSG_CTRUNC;
235 cmlen = msg->msg_controllen;
237 cmhdr.cmsg_level = level;
238 cmhdr.cmsg_type = type;
239 cmhdr.cmsg_len = cmlen;
242 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
244 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
246 cmlen = CMSG_SPACE(len);
247 if (msg->msg_controllen < cmlen)
248 cmlen = msg->msg_controllen;
249 msg->msg_control += cmlen;
250 msg->msg_controllen -= cmlen;
255 EXPORT_SYMBOL(put_cmsg);
257 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
259 struct cmsghdr __user *cm
260 = (__force struct cmsghdr __user*)msg->msg_control;
263 int fdnum = scm->fp->count;
264 struct file **fp = scm->fp->fp;
268 if (MSG_CMSG_COMPAT & msg->msg_flags) {
269 scm_detach_fds_compat(msg, scm);
273 if (msg->msg_controllen > sizeof(struct cmsghdr))
274 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
280 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
285 err = security_file_receive(fp[i]);
288 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
293 err = put_user(new_fd, cmfptr);
295 put_unused_fd(new_fd);
298 /* Bump the usage count and install the file. */
300 sock = sock_from_file(fp[i], &err);
302 sock_update_netprioidx(sock->sk, current);
303 fd_install(new_fd, fp[i]);
308 int cmlen = CMSG_LEN(i*sizeof(int));
309 err = put_user(SOL_SOCKET, &cm->cmsg_level);
311 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
313 err = put_user(cmlen, &cm->cmsg_len);
315 cmlen = CMSG_SPACE(i*sizeof(int));
316 msg->msg_control += cmlen;
317 msg->msg_controllen -= cmlen;
320 if (i < fdnum || (fdnum && fdmax <= 0))
321 msg->msg_flags |= MSG_CTRUNC;
324 * All of the files that fit in the message have had their
325 * usage counts incremented, so we just free the list.
329 EXPORT_SYMBOL(scm_detach_fds);
331 struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
333 struct scm_fp_list *new_fpl;
339 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
342 for (i = 0; i < fpl->count; i++)
343 get_file(fpl->fp[i]);
344 new_fpl->max = new_fpl->count;
348 EXPORT_SYMBOL(scm_fp_dup);