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_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 203                                void *data, size_t size)
 204 {
 205         __do_free char *cmsgbuf = NULL;
 206         int ret;
 207         struct msghdr msg;
 208         struct iovec iov;
 209         struct cmsghdr *cmsg = NULL;
 210         char buf[1] = {0};
 211         size_t cmsgbufsize = CMSG_SPACE(sizeof(struct ucred)) +
 212                              CMSG_SPACE(num_recvfds * sizeof(int));
 213
 214         memset(&msg, 0, sizeof(msg));
 215         memset(&iov, 0, sizeof(iov));
 216
 217         cmsgbuf = malloc(cmsgbufsize);
 218         if (!cmsgbuf) {
 219                 errno = ENOMEM;
 220                 return -1;
 221         }
 222
 223         msg.msg_control = cmsgbuf;
 224         msg.msg_controllen = cmsgbufsize;
 225
 226         iov.iov_base = data ? data : buf;
 227         iov.iov_len = data ? size : sizeof(buf);
 228         msg.msg_iov = &iov;
 229         msg.msg_iovlen = 1;
 230
 231 again:
 232         ret = recvmsg(fd, &msg, 0);
 233         if (ret < 0) {
 234                 if (errno == EINTR)
 235                         goto again;
 236
 237                 goto out;
 238         }
 239         if (ret == 0)
 240                 goto out;
 241
 242         /*
 243          * If SO_PASSCRED is set we will always get a ucred message.
 244          */
 245         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 246                 if (cmsg->cmsg_type != SCM_RIGHTS)
 247                         continue;
 248
 249                 memset(recvfds, -1, num_recvfds * sizeof(int));
 250                 if (cmsg &&
 251                     cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 252                     cmsg->cmsg_level == SOL_SOCKET)
 253                         memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 254                 break;
 255         }
 256
 257 out:
 258         return ret;
 259 }
 260
 261 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 262 {
 263         struct msghdr msg = {0};
 264         struct iovec iov;
 265         struct cmsghdr *cmsg;
 266         struct ucred cred = {
 267             .pid = lxc_raw_getpid(), .uid = getuid(), .gid = getgid(),
 268         };
 269         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 270         char buf[1] = {0};
 271
 272         msg.msg_control = cmsgbuf;
 273         msg.msg_controllen = sizeof(cmsgbuf);
 274
 275         cmsg = CMSG_FIRSTHDR(&msg);
 276         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 277         cmsg->cmsg_level = SOL_SOCKET;
 278         cmsg->cmsg_type = SCM_CREDENTIALS;
 279         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 280
 281         msg.msg_name = NULL;
 282         msg.msg_namelen = 0;
 283
 284         iov.iov_base = data ? data : buf;
 285         iov.iov_len = data ? size : sizeof(buf);
 286         msg.msg_iov = &iov;
 287         msg.msg_iovlen = 1;
 288
 289         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 290 }
 291
 292 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 293 {
 294         struct msghdr msg = {0};
 295         struct iovec iov;
 296         struct cmsghdr *cmsg;
 297         struct ucred cred;
 298         int ret;
 299         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 300         char buf[1] = {0};
 301
 302         msg.msg_name = NULL;
 303         msg.msg_namelen = 0;
 304         msg.msg_control = cmsgbuf;
 305         msg.msg_controllen = sizeof(cmsgbuf);
 306
 307         iov.iov_base = data ? data : buf;
 308         iov.iov_len = data ? size : sizeof(buf);
 309         msg.msg_iov = &iov;
 310         msg.msg_iovlen = 1;
 311
 312         ret = recvmsg(fd, &msg, 0);
 313         if (ret <= 0)
 314                 goto out;
 315
 316         cmsg = CMSG_FIRSTHDR(&msg);
 317
 318         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 319             cmsg->cmsg_level == SOL_SOCKET &&
 320             cmsg->cmsg_type == SCM_CREDENTIALS) {
 321                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 322                 if (cred.uid &&
 323                     (cred.uid != getuid() || cred.gid != getgid())) {
 324                         INFO("Message denied for '%d/%d'", cred.uid, cred.gid);
 325                         errno = EACCES;
 326                         return -1;
 327                 }
 328         }
 329
 330 out:
 331         return ret;
 332 }
 333
 334 int lxc_unix_sockaddr(struct sockaddr_un *ret, const char *path)
 335 {
 336         size_t len;
 337
 338         len = strlen(path);
 339         if (len == 0)
 340                 return minus_one_set_errno(EINVAL);
 341         if (path[0] != '/' && path[0] != '@')
 342                 return minus_one_set_errno(EINVAL);
 343         if (path[1] == '\0')
 344                 return minus_one_set_errno(EINVAL);
 345
 346         if (len + 1 > sizeof(ret->sun_path))
 347                 return minus_one_set_errno(EINVAL);
 348
 349         *ret = (struct sockaddr_un){
 350             .sun_family = AF_UNIX,
 351         };
 352
 353         if (path[0] == '@') {
 354                 memcpy(ret->sun_path + 1, path + 1, len);
 355                 return (int)(offsetof(struct sockaddr_un, sun_path) + len);
 356         }
 357
 358         memcpy(ret->sun_path, path, len + 1);
 359         return (int)(offsetof(struct sockaddr_un, sun_path) + len + 1);
 360 }
 361
 362 int lxc_unix_connect(struct sockaddr_un *addr)
 363 {
 364         __do_close_prot_errno int fd = -EBADF;
 365         int ret;
 366         ssize_t len;
 367
 368         fd = socket(AF_UNIX, SOCK_STREAM, 0);
 369         if (fd < 0) {
 370                 SYSERROR("Failed to open new AF_UNIX socket");
 371                 return -1;
 372         }
 373
 374         if (addr->sun_path[0] == '\0')
 375                 len = strlen(&addr->sun_path[1]);
 376         else
 377                 len = strlen(&addr->sun_path[0]);
 378
 379         ret = connect(fd, (struct sockaddr *)addr,
 380                       offsetof(struct sockaddr_un, sun_path) + len);
 381         if (ret < 0) {
 382                 SYSERROR("Failed to bind new AF_UNIX socket");
 383                 return -1;
 384         }
 385
 386         return move_fd(fd);
 387 }
 388
 389 int lxc_socket_set_timeout(int fd, int rcv_timeout, int snd_timeout)
 390 {
 391         struct timeval out = {0};
 392         int ret;
 393
 394         out.tv_sec = snd_timeout;
 395         ret = setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, (const void *)&out,
 396                          sizeof(out));
 397         if (ret < 0)
 398                 return -1;
 399
 400         out.tv_sec = rcv_timeout;
 401         ret = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (const void *)&out,
 402                          sizeof(out));
 403         if (ret < 0)
 404                 return -1;
 405
 406         return 0;
 407 }