Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Randy Dunlap | 4fc268d | 2006-01-11 12:17:47 -0800 | [diff] [blame] | 14 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | #include <linux/errno.h> |
| 16 | #include <linux/sched.h> |
| 17 | #include <linux/mm.h> |
| 18 | #include <linux/kernel.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 27 | #include <linux/pid.h> |
| 28 | #include <linux/nsproxy.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 29 | #include <linux/slab.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | |
| 31 | #include <asm/system.h> |
| 32 | #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> |
| 39 | |
| 40 | |
| 41 | /* |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 42 | * Only allow a user to send credentials, that they could set with |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | * setu(g)id. |
| 44 | */ |
| 45 | |
| 46 | static __inline__ int scm_check_creds(struct ucred *creds) |
| 47 | { |
David Howells | 86a264a | 2008-11-14 10:39:18 +1100 | [diff] [blame] | 48 | const struct cred *cred = current_cred(); |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 49 | |
Pavel Emelyanov | b488893 | 2007-10-18 23:40:14 -0700 | [diff] [blame] | 50 | if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) && |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 51 | ((creds->uid == cred->uid || creds->uid == cred->euid || |
| 52 | creds->uid == cred->suid) || capable(CAP_SETUID)) && |
| 53 | ((creds->gid == cred->gid || creds->gid == cred->egid || |
| 54 | creds->gid == cred->sgid) || capable(CAP_SETGID))) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 55 | return 0; |
| 56 | } |
| 57 | return -EPERM; |
| 58 | } |
| 59 | |
| 60 | static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp) |
| 61 | { |
| 62 | int *fdp = (int*)CMSG_DATA(cmsg); |
| 63 | struct scm_fp_list *fpl = *fplp; |
| 64 | struct file **fpp; |
| 65 | int i, num; |
| 66 | |
| 67 | num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int); |
| 68 | |
| 69 | if (num <= 0) |
| 70 | return 0; |
| 71 | |
| 72 | if (num > SCM_MAX_FD) |
| 73 | return -EINVAL; |
| 74 | |
| 75 | if (!fpl) |
| 76 | { |
| 77 | fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL); |
| 78 | if (!fpl) |
| 79 | return -ENOMEM; |
| 80 | *fplp = fpl; |
| 81 | fpl->count = 0; |
| 82 | } |
| 83 | fpp = &fpl->fp[fpl->count]; |
| 84 | |
| 85 | if (fpl->count + num > SCM_MAX_FD) |
| 86 | return -EINVAL; |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 87 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | /* |
| 89 | * Verify the descriptors and increment the usage count. |
| 90 | */ |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 91 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | for (i=0; i< num; i++) |
| 93 | { |
| 94 | int fd = fdp[i]; |
| 95 | struct file *file; |
| 96 | |
| 97 | if (fd < 0 || !(file = fget(fd))) |
| 98 | return -EBADF; |
| 99 | *fpp++ = file; |
| 100 | fpl->count++; |
| 101 | } |
| 102 | return num; |
| 103 | } |
| 104 | |
| 105 | void __scm_destroy(struct scm_cookie *scm) |
| 106 | { |
| 107 | struct scm_fp_list *fpl = scm->fp; |
| 108 | int i; |
| 109 | |
| 110 | if (fpl) { |
| 111 | scm->fp = NULL; |
David Miller | f8d570a | 2008-11-06 00:37:40 -0800 | [diff] [blame] | 112 | if (current->scm_work_list) { |
| 113 | list_add_tail(&fpl->list, current->scm_work_list); |
| 114 | } else { |
| 115 | LIST_HEAD(work_list); |
| 116 | |
| 117 | current->scm_work_list = &work_list; |
| 118 | |
| 119 | list_add(&fpl->list, &work_list); |
| 120 | while (!list_empty(&work_list)) { |
| 121 | fpl = list_first_entry(&work_list, struct scm_fp_list, list); |
| 122 | |
| 123 | list_del(&fpl->list); |
| 124 | for (i=fpl->count-1; i>=0; i--) |
| 125 | fput(fpl->fp[i]); |
| 126 | kfree(fpl); |
| 127 | } |
| 128 | |
| 129 | current->scm_work_list = NULL; |
| 130 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | } |
| 132 | } |
| 133 | |
| 134 | int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p) |
| 135 | { |
| 136 | struct cmsghdr *cmsg; |
| 137 | int err; |
| 138 | |
| 139 | for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) |
| 140 | { |
| 141 | err = -EINVAL; |
| 142 | |
| 143 | /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */ |
| 144 | /* The first check was omitted in <= 2.2.5. The reasoning was |
| 145 | that parser checks cmsg_len in any case, so that |
| 146 | additional check would be work duplication. |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 147 | But if cmsg_level is not SOL_SOCKET, we do not check |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 148 | for too short ancillary data object at all! Oops. |
| 149 | OK, let's add it... |
| 150 | */ |
| 151 | if (!CMSG_OK(msg, cmsg)) |
| 152 | goto error; |
| 153 | |
| 154 | if (cmsg->cmsg_level != SOL_SOCKET) |
| 155 | continue; |
| 156 | |
| 157 | switch (cmsg->cmsg_type) |
| 158 | { |
| 159 | case SCM_RIGHTS: |
Eric W. Biederman | 76dadd76 | 2010-02-28 01:20:36 +0000 | [diff] [blame] | 160 | if (!sock->ops || sock->ops->family != PF_UNIX) |
| 161 | goto error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 162 | err=scm_fp_copy(cmsg, &p->fp); |
| 163 | if (err<0) |
| 164 | goto error; |
| 165 | break; |
| 166 | case SCM_CREDENTIALS: |
| 167 | if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred))) |
| 168 | goto error; |
| 169 | memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred)); |
| 170 | err = scm_check_creds(&p->creds); |
| 171 | if (err) |
| 172 | goto error; |
Eric W. Biederman | 257b535 | 2010-06-13 03:32:34 +0000 | [diff] [blame^] | 173 | |
| 174 | if (pid_vnr(p->pid) != p->creds.pid) { |
| 175 | struct pid *pid; |
| 176 | err = -ESRCH; |
| 177 | pid = find_get_pid(p->creds.pid); |
| 178 | if (!pid) |
| 179 | goto error; |
| 180 | put_pid(p->pid); |
| 181 | p->pid = pid; |
| 182 | } |
| 183 | |
| 184 | if ((p->cred->euid != p->creds.uid) || |
| 185 | (p->cred->egid != p->creds.gid)) { |
| 186 | struct cred *cred; |
| 187 | err = -ENOMEM; |
| 188 | cred = prepare_creds(); |
| 189 | if (!cred) |
| 190 | goto error; |
| 191 | |
| 192 | cred->uid = cred->euid = p->creds.uid; |
| 193 | cred->gid = cred->egid = p->creds.uid; |
| 194 | put_cred(p->cred); |
| 195 | p->cred = cred; |
| 196 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | break; |
| 198 | default: |
| 199 | goto error; |
| 200 | } |
| 201 | } |
| 202 | |
| 203 | if (p->fp && !p->fp->count) |
| 204 | { |
| 205 | kfree(p->fp); |
| 206 | p->fp = NULL; |
| 207 | } |
| 208 | return 0; |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 209 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 210 | error: |
| 211 | scm_destroy(p); |
| 212 | return err; |
| 213 | } |
| 214 | |
| 215 | int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data) |
| 216 | { |
Stephen Hemminger | cfcabdc | 2007-10-09 01:59:42 -0700 | [diff] [blame] | 217 | struct cmsghdr __user *cm |
| 218 | = (__force struct cmsghdr __user *)msg->msg_control; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 219 | struct cmsghdr cmhdr; |
| 220 | int cmlen = CMSG_LEN(len); |
| 221 | int err; |
| 222 | |
| 223 | if (MSG_CMSG_COMPAT & msg->msg_flags) |
| 224 | return put_cmsg_compat(msg, level, type, len, data); |
| 225 | |
| 226 | if (cm==NULL || msg->msg_controllen < sizeof(*cm)) { |
| 227 | msg->msg_flags |= MSG_CTRUNC; |
| 228 | return 0; /* XXX: return error? check spec. */ |
| 229 | } |
| 230 | if (msg->msg_controllen < cmlen) { |
| 231 | msg->msg_flags |= MSG_CTRUNC; |
| 232 | cmlen = msg->msg_controllen; |
| 233 | } |
| 234 | cmhdr.cmsg_level = level; |
| 235 | cmhdr.cmsg_type = type; |
| 236 | cmhdr.cmsg_len = cmlen; |
| 237 | |
| 238 | err = -EFAULT; |
| 239 | if (copy_to_user(cm, &cmhdr, sizeof cmhdr)) |
YOSHIFUJI Hideaki | 4ec93ed | 2007-02-09 23:24:36 +0900 | [diff] [blame] | 240 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 241 | if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr))) |
| 242 | goto out; |
| 243 | cmlen = CMSG_SPACE(len); |
Wei Yongjun | 1ac70e7 | 2007-12-20 14:36:44 -0800 | [diff] [blame] | 244 | if (msg->msg_controllen < cmlen) |
| 245 | cmlen = msg->msg_controllen; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 246 | msg->msg_control += cmlen; |
| 247 | msg->msg_controllen -= cmlen; |
| 248 | err = 0; |
| 249 | out: |
| 250 | return err; |
| 251 | } |
| 252 | |
| 253 | void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm) |
| 254 | { |
Stephen Hemminger | cfcabdc | 2007-10-09 01:59:42 -0700 | [diff] [blame] | 255 | struct cmsghdr __user *cm |
| 256 | = (__force struct cmsghdr __user*)msg->msg_control; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 257 | |
| 258 | int fdmax = 0; |
| 259 | int fdnum = scm->fp->count; |
| 260 | struct file **fp = scm->fp->fp; |
| 261 | int __user *cmfptr; |
| 262 | int err = 0, i; |
| 263 | |
| 264 | if (MSG_CMSG_COMPAT & msg->msg_flags) { |
| 265 | scm_detach_fds_compat(msg, scm); |
| 266 | return; |
| 267 | } |
| 268 | |
| 269 | if (msg->msg_controllen > sizeof(struct cmsghdr)) |
| 270 | fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr)) |
| 271 | / sizeof(int)); |
| 272 | |
| 273 | if (fdnum < fdmax) |
| 274 | fdmax = fdnum; |
| 275 | |
Stephen Hemminger | cfcabdc | 2007-10-09 01:59:42 -0700 | [diff] [blame] | 276 | for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax; |
| 277 | i++, cmfptr++) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 278 | { |
| 279 | int new_fd; |
| 280 | err = security_file_receive(fp[i]); |
| 281 | if (err) |
| 282 | break; |
Ulrich Drepper | 4a19542 | 2007-07-15 23:40:34 -0700 | [diff] [blame] | 283 | err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags |
| 284 | ? O_CLOEXEC : 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 285 | if (err < 0) |
| 286 | break; |
| 287 | new_fd = err; |
| 288 | err = put_user(new_fd, cmfptr); |
| 289 | if (err) { |
| 290 | put_unused_fd(new_fd); |
| 291 | break; |
| 292 | } |
| 293 | /* Bump the usage count and install the file. */ |
| 294 | get_file(fp[i]); |
| 295 | fd_install(new_fd, fp[i]); |
| 296 | } |
| 297 | |
| 298 | if (i > 0) |
| 299 | { |
| 300 | int cmlen = CMSG_LEN(i*sizeof(int)); |
Miklos Szeredi | effee6a | 2006-10-09 21:42:14 -0700 | [diff] [blame] | 301 | err = put_user(SOL_SOCKET, &cm->cmsg_level); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 302 | 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)); |
| 308 | msg->msg_control += cmlen; |
| 309 | msg->msg_controllen -= cmlen; |
| 310 | } |
| 311 | } |
| 312 | if (i < fdnum || (fdnum && fdmax <= 0)) |
| 313 | msg->msg_flags |= MSG_CTRUNC; |
| 314 | |
| 315 | /* |
| 316 | * All of the files that fit in the message have had their |
| 317 | * usage counts incremented, so we just free the list. |
| 318 | */ |
| 319 | __scm_destroy(scm); |
| 320 | } |
| 321 | |
| 322 | struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl) |
| 323 | { |
| 324 | struct scm_fp_list *new_fpl; |
| 325 | int i; |
| 326 | |
| 327 | if (!fpl) |
| 328 | return NULL; |
| 329 | |
| 330 | new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL); |
| 331 | if (new_fpl) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 332 | for (i=fpl->count-1; i>=0; i--) |
| 333 | get_file(fpl->fp[i]); |
| 334 | memcpy(new_fpl, fpl, sizeof(*fpl)); |
| 335 | } |
| 336 | return new_fpl; |
| 337 | } |
| 338 | |
| 339 | EXPORT_SYMBOL(__scm_destroy); |
| 340 | EXPORT_SYMBOL(__scm_send); |
| 341 | EXPORT_SYMBOL(put_cmsg); |
| 342 | EXPORT_SYMBOL(scm_detach_fds); |
| 343 | EXPORT_SYMBOL(scm_fp_dup); |