src/lxc/af_unix.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE 1
  26 #endif
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <stddef.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34 #include <sys/socket.h>
  35 #include <sys/syscall.h>
  36 #include <sys/un.h>
  37
  38 #include "config.h"
  39 #include "log.h"
  40 #include "memory_utils.h"
  41 #include "raw_syscalls.h"
  42 #include "utils.h"
  43
  44 #ifndef HAVE_STRLCPY
  45 #include "include/strlcpy.h"
  46 #endif
  47
  48 lxc_log_define(af_unix, lxc);
  49
  50 static ssize_t lxc_abstract_unix_set_sockaddr(struct sockaddr_un *addr,
  51                                 const char *path)
  52 {
  53         size_t len;
  54
  55         if (!addr || !path) {
  56                 errno = EINVAL;
  57                 return -1;
  58         }
  59
  60         /* Clear address structure */
  61         memset(addr, 0, sizeof(*addr));
  62
  63         addr->sun_family = AF_UNIX;
  64
  65         len = strlen(&path[1]);
  66
  67         /* do not enforce \0-termination */
  68         if (len >= INT_MAX || len >= sizeof(addr->sun_path)) {
  69                 errno = ENAMETOOLONG;
  70                 return -1;
  71         }
  72
  73         /* do not enforce \0-termination */
  74         memcpy(&addr->sun_path[1], &path[1], len);
  75         return len;
  76 }
  77
  78 int lxc_abstract_unix_open(const char *path, int type, int flags)
  79 {
  80         int fd, ret;
  81         ssize_t len;
  82         struct sockaddr_un addr;
  83
  84         fd = socket(PF_UNIX, type, 0);
  85         if (fd < 0)
  86                 return -1;
  87
  88         if (!path)
  89                 return fd;
  90
  91         len = lxc_abstract_unix_set_sockaddr(&addr, path);
  92         if (len < 0) {
  93                 int saved_errno = errno;
  94                 close(fd);
  95                 errno = saved_errno;
  96                 return -1;
  97         }
  98
  99         ret = bind(fd, (struct sockaddr *)&addr,
 100                    offsetof(struct sockaddr_un, sun_path) + len + 1);
 101         if (ret < 0) {
 102                 int saved_errno = errno;
 103                 close(fd);
 104                 errno = saved_errno;
 105                 return -1;
 106         }
 107
 108         if (type == SOCK_STREAM) {
 109                 ret = listen(fd, 100);
 110                 if (ret < 0) {
 111                         int saved_errno = errno;
 112                         close(fd);
 113                         errno = saved_errno;
 114                         return -1;
 115                 }
 116         }
 117
 118         return fd;
 119 }
 120
 121 void lxc_abstract_unix_close(int fd)
 122 {
 123         close(fd);
 124 }
 125
 126 int lxc_abstract_unix_connect(const char *path)
 127 {
 128         int fd, ret;
 129         ssize_t len;
 130         struct sockaddr_un addr;
 131
 132         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 133         if (fd < 0)
 134                 return -1;
 135
 136         len = lxc_abstract_unix_set_sockaddr(&addr, path);
 137         if (len < 0) {
 138                 int saved_errno = errno;
 139                 close(fd);
 140                 errno = saved_errno;
 141                 return -1;
 142         }
 143
 144         ret = connect(fd, (struct sockaddr *)&addr,
 145                       offsetof(struct sockaddr_un, sun_path) + len + 1);
 146         if (ret < 0) {
 147                 int saved_errno = errno;
 148                 close(fd);
 149                 errno = saved_errno;
 150                 return -1;
 151         }
 152
 153         return fd;
 154 }
 155
 156 int lxc_abstract_unix_send_fds(int fd, int *sendfds, int num_sendfds,
 157                                void *data, size_t size)
 158 {
 159         __do_free char *cmsgbuf = NULL;
 160         int ret;
 161         struct msghdr msg;
 162         struct iovec iov;
 163         struct cmsghdr *cmsg = NULL;
 164         char buf[1] = {0};
 165         size_t cmsgbufsize = CMSG_SPACE(num_sendfds * sizeof(int));
 166
 167         memset(&msg, 0, sizeof(msg));
 168         memset(&iov, 0, sizeof(iov));
 169
 170         cmsgbuf = malloc(cmsgbufsize);
 171         if (!cmsgbuf) {
 172                 errno = ENOMEM;
 173                 return -1;
 174         }
 175
 176         msg.msg_control = cmsgbuf;
 177         msg.msg_controllen = cmsgbufsize;
 178
 179         cmsg = CMSG_FIRSTHDR(&msg);
 180         cmsg->cmsg_level = SOL_SOCKET;
 181         cmsg->cmsg_type = SCM_RIGHTS;
 182         cmsg->cmsg_len = CMSG_LEN(num_sendfds * sizeof(int));
 183
 184         msg.msg_controllen = cmsg->cmsg_len;
 185
 186         memcpy(CMSG_DATA(cmsg), sendfds, num_sendfds * sizeof(int));
 187
 188         iov.iov_base = data ? data : buf;
 189         iov.iov_len = data ? size : sizeof(buf);
 190         msg.msg_iov = &iov;
 191         msg.msg_iovlen = 1;
 192
 193 again:
 194         ret = sendmsg(fd, &msg, MSG_NOSIGNAL);
 195         if (ret < 0)
 196                 if (errno == EINTR)
 197                         goto again;
 198
 199         return ret;
 200 }
 201
 202 int lxc_unix_send_fds(int fd, int *sendfds, int num_sendfds, void *data,
 203                       size_t size)
 204 {
 205         return lxc_abstract_unix_send_fds(fd, sendfds, num_sendfds, data, size);
 206 }
 207
 208 int lxc_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 209                                void *data, size_t size)
 210 {
 211         __do_free char *cmsgbuf = NULL;
 212         int ret;
 213         struct msghdr msg;
 214         struct iovec iov;
 215         struct cmsghdr *cmsg = NULL;
 216         char buf[1] = {0};
 217         size_t cmsgbufsize = CMSG_SPACE(sizeof(struct ucred)) +
 218                              CMSG_SPACE(num_recvfds * sizeof(int));
 219
 220         memset(&msg, 0, sizeof(msg));
 221         memset(&iov, 0, sizeof(iov));
 222
 223         cmsgbuf = malloc(cmsgbufsize);
 224         if (!cmsgbuf) {
 225                 errno = ENOMEM;
 226                 return -1;
 227         }
 228
 229         msg.msg_control = cmsgbuf;
 230         msg.msg_controllen = cmsgbufsize;
 231
 232         iov.iov_base = data ? data : buf;
 233         iov.iov_len = data ? size : sizeof(buf);
 234         msg.msg_iov = &iov;
 235         msg.msg_iovlen = 1;
 236
 237 again:
 238         ret = recvmsg(fd, &msg, 0);
 239         if (ret < 0) {
 240                 if (errno == EINTR)
 241                         goto again;
 242
 243                 goto out;
 244         }
 245         if (ret == 0)
 246                 goto out;
 247
 248         /*
 249          * If SO_PASSCRED is set we will always get a ucred message.
 250          */
 251         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 252                 if (cmsg->cmsg_type != SCM_RIGHTS)
 253                         continue;
 254
 255                 memset(recvfds, -1, num_recvfds * sizeof(int));
 256                 if (cmsg &&
 257                     cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 258                     cmsg->cmsg_level == SOL_SOCKET)
 259                         memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 260                 break;
 261         }
 262
 263 out:
 264         return ret;
 265 }
 266
 267 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 268 {
 269         struct msghdr msg = {0};
 270         struct iovec iov;
 271         struct cmsghdr *cmsg;
 272         struct ucred cred = {
 273             .pid = lxc_raw_getpid(), .uid = getuid(), .gid = getgid(),
 274         };
 275         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 276         char buf[1] = {0};
 277
 278         msg.msg_control = cmsgbuf;
 279         msg.msg_controllen = sizeof(cmsgbuf);
 280
 281         cmsg = CMSG_FIRSTHDR(&msg);
 282         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 283         cmsg->cmsg_level = SOL_SOCKET;
 284         cmsg->cmsg_type = SCM_CREDENTIALS;
 285         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 286
 287         msg.msg_name = NULL;
 288         msg.msg_namelen = 0;
 289
 290         iov.iov_base = data ? data : buf;
 291         iov.iov_len = data ? size : sizeof(buf);
 292         msg.msg_iov = &iov;
 293         msg.msg_iovlen = 1;
 294
 295         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 296 }
 297
 298 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 299 {
 300         struct msghdr msg = {0};
 301         struct iovec iov;
 302         struct cmsghdr *cmsg;
 303         struct ucred cred;
 304         int ret;
 305         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 306         char buf[1] = {0};
 307
 308         msg.msg_name = NULL;
 309         msg.msg_namelen = 0;
 310         msg.msg_control = cmsgbuf;
 311         msg.msg_controllen = sizeof(cmsgbuf);
 312
 313         iov.iov_base = data ? data : buf;
 314         iov.iov_len = data ? size : sizeof(buf);
 315         msg.msg_iov = &iov;
 316         msg.msg_iovlen = 1;
 317
 318         ret = recvmsg(fd, &msg, 0);
 319         if (ret <= 0)
 320                 goto out;
 321
 322         cmsg = CMSG_FIRSTHDR(&msg);
 323
 324         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 325             cmsg->cmsg_level == SOL_SOCKET &&
 326             cmsg->cmsg_type == SCM_CREDENTIALS) {
 327                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 328                 if (cred.uid &&
 329                     (cred.uid != getuid() || cred.gid != getgid())) {
 330                         INFO("Message denied for '%d/%d'", cred.uid, cred.gid);
 331                         errno = EACCES;
 332                         return -1;
 333                 }
 334         }
 335
 336 out:
 337         return ret;
 338 }
 339
 340 int lxc_unix_sockaddr(struct sockaddr_un *ret, const char *path)
 341 {
 342         size_t len;
 343
 344         len = strlen(path);
 345         if (len == 0)
 346                 return minus_one_set_errno(EINVAL);
 347         if (path[0] != '/' && path[0] != '@')
 348                 return minus_one_set_errno(EINVAL);
 349         if (path[1] == '\0')
 350                 return minus_one_set_errno(EINVAL);
 351
 352         if (len + 1 > sizeof(ret->sun_path))
 353                 return minus_one_set_errno(EINVAL);
 354
 355         *ret = (struct sockaddr_un){
 356             .sun_family = AF_UNIX,
 357         };
 358
 359         if (path[0] == '@') {
 360                 memcpy(ret->sun_path + 1, path + 1, len);
 361                 return (int)(offsetof(struct sockaddr_un, sun_path) + len);
 362         }
 363
 364         memcpy(ret->sun_path, path, len + 1);
 365         return (int)(offsetof(struct sockaddr_un, sun_path) + len + 1);
 366 }
 367
 368 int lxc_unix_connect(struct sockaddr_un *addr)
 369 {
 370         __do_close_prot_errno int fd = -EBADF;
 371         int ret;
 372         ssize_t len;
 373
 374         fd = socket(AF_UNIX, SOCK_STREAM, 0);
 375         if (fd < 0) {
 376                 SYSERROR("Failed to open new AF_UNIX socket");
 377                 return -1;
 378         }
 379
 380         if (addr->sun_path[0] == '\0')
 381                 len = strlen(&addr->sun_path[1]);
 382         else
 383                 len = strlen(&addr->sun_path[0]);
 384
 385         ret = connect(fd, (struct sockaddr *)addr,
 386                       offsetof(struct sockaddr_un, sun_path) + len);
 387         if (ret < 0) {
 388                 SYSERROR("Failed to bind new AF_UNIX socket");
 389                 return -1;
 390         }
 391
 392         return move_fd(fd);
 393 }
 394
 395 int lxc_socket_set_timeout(int fd, int rcv_timeout, int snd_timeout)
 396 {
 397         struct timeval out = {0};
 398         int ret;
 399
 400         out.tv_sec = snd_timeout;
 401         ret = setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, (const void *)&out,
 402                          sizeof(out));
 403         if (ret < 0)
 404                 return -1;
 405
 406         out.tv_sec = rcv_timeout;
 407         ret = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (const void *)&out,
 408                          sizeof(out));
 409         if (ret < 0)
 410                 return -1;
 411
 412         return 0;
 413 }