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 | SOCK_CLOEXEC, 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 | SOCK_CLOEXEC, 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_iov(int fd, int *sendfds, int num_sendfds,
 157                                    struct iovec *iov, size_t iovlen)
 158 {
 159         __do_free char *cmsgbuf = NULL;
 160         int ret;
 161         struct msghdr msg;
 162         struct cmsghdr *cmsg = NULL;
 163         size_t cmsgbufsize = CMSG_SPACE(num_sendfds * sizeof(int));
 164
 165         memset(&msg, 0, sizeof(msg));
 166
 167         cmsgbuf = malloc(cmsgbufsize);
 168         if (!cmsgbuf) {
 169                 errno = ENOMEM;
 170                 return -1;
 171         }
 172
 173         msg.msg_control = cmsgbuf;
 174         msg.msg_controllen = cmsgbufsize;
 175
 176         cmsg = CMSG_FIRSTHDR(&msg);
 177         cmsg->cmsg_level = SOL_SOCKET;
 178         cmsg->cmsg_type = SCM_RIGHTS;
 179         cmsg->cmsg_len = CMSG_LEN(num_sendfds * sizeof(int));
 180
 181         msg.msg_controllen = cmsg->cmsg_len;
 182
 183         memcpy(CMSG_DATA(cmsg), sendfds, num_sendfds * sizeof(int));
 184
 185         msg.msg_iov = iov;
 186         msg.msg_iovlen = iovlen;
 187
 188 again:
 189         ret = sendmsg(fd, &msg, MSG_NOSIGNAL);
 190         if (ret < 0)
 191                 if (errno == EINTR)
 192                         goto again;
 193
 194         return ret;
 195 }
 196
 197 int lxc_abstract_unix_send_fds(int fd, int *sendfds, int num_sendfds,
 198                                void *data, size_t size)
 199 {
 200         char buf[1] = {0};
 201         struct iovec iov = {
 202                 .iov_base = data ? data : buf,
 203                 .iov_len = data ? size : sizeof(buf),
 204         };
 205         return lxc_abstract_unix_send_fds_iov(fd, sendfds, num_sendfds, &iov,
 206                                               1);
 207 }
 208
 209 int lxc_unix_send_fds(int fd, int *sendfds, int num_sendfds, void *data,
 210                       size_t size)
 211 {
 212         return lxc_abstract_unix_send_fds(fd, sendfds, num_sendfds, data, size);
 213 }
 214
 215 static int lxc_abstract_unix_recv_fds_iov(int fd, int *recvfds, int num_recvfds,
 216                                           struct iovec *iov, size_t iovlen)
 217 {
 218         __do_free char *cmsgbuf = NULL;
 219         int ret;
 220         struct msghdr msg;
 221         struct cmsghdr *cmsg = NULL;
 222         char buf[1] = {0};
 223         size_t cmsgbufsize = CMSG_SPACE(sizeof(struct ucred)) +
 224                              CMSG_SPACE(num_recvfds * sizeof(int));
 225
 226         memset(&msg, 0, sizeof(msg));
 227
 228         cmsgbuf = malloc(cmsgbufsize);
 229         if (!cmsgbuf) {
 230                 errno = ENOMEM;
 231                 return -1;
 232         }
 233
 234         msg.msg_control = cmsgbuf;
 235         msg.msg_controllen = cmsgbufsize;
 236
 237         msg.msg_iov = iov;
 238         msg.msg_iovlen = iovlen;
 239
 240 again:
 241         ret = recvmsg(fd, &msg, 0);
 242         if (ret < 0) {
 243                 if (errno == EINTR)
 244                         goto again;
 245
 246                 goto out;
 247         }
 248         if (ret == 0)
 249                 goto out;
 250
 251         /*
 252          * If SO_PASSCRED is set we will always get a ucred message.
 253          */
 254         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 255                 if (cmsg->cmsg_type != SCM_RIGHTS)
 256                         continue;
 257
 258                 memset(recvfds, -1, num_recvfds * sizeof(int));
 259                 if (cmsg &&
 260                     cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 261                     cmsg->cmsg_level == SOL_SOCKET)
 262                         memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 263                 break;
 264         }
 265
 266 out:
 267         return ret;
 268 }
 269
 270 int lxc_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 271                                void *data, size_t size)
 272 {
 273         char buf[1] = {0};
 274         struct iovec iov = {
 275                 .iov_base = data ? data : buf,
 276                 .iov_len = data ? size : sizeof(buf),
 277         };
 278         return lxc_abstract_unix_recv_fds_iov(fd, recvfds, num_recvfds, &iov, 1);
 279 }
 280
 281 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 282 {
 283         struct msghdr msg = {0};
 284         struct iovec iov;
 285         struct cmsghdr *cmsg;
 286         struct ucred cred = {
 287             .pid = lxc_raw_getpid(), .uid = getuid(), .gid = getgid(),
 288         };
 289         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 290         char buf[1] = {0};
 291
 292         msg.msg_control = cmsgbuf;
 293         msg.msg_controllen = sizeof(cmsgbuf);
 294
 295         cmsg = CMSG_FIRSTHDR(&msg);
 296         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 297         cmsg->cmsg_level = SOL_SOCKET;
 298         cmsg->cmsg_type = SCM_CREDENTIALS;
 299         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 300
 301         msg.msg_name = NULL;
 302         msg.msg_namelen = 0;
 303
 304         iov.iov_base = data ? data : buf;
 305         iov.iov_len = data ? size : sizeof(buf);
 306         msg.msg_iov = &iov;
 307         msg.msg_iovlen = 1;
 308
 309         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 310 }
 311
 312 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 313 {
 314         struct msghdr msg = {0};
 315         struct iovec iov;
 316         struct cmsghdr *cmsg;
 317         struct ucred cred;
 318         int ret;
 319         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 320         char buf[1] = {0};
 321
 322         msg.msg_name = NULL;
 323         msg.msg_namelen = 0;
 324         msg.msg_control = cmsgbuf;
 325         msg.msg_controllen = sizeof(cmsgbuf);
 326
 327         iov.iov_base = data ? data : buf;
 328         iov.iov_len = data ? size : sizeof(buf);
 329         msg.msg_iov = &iov;
 330         msg.msg_iovlen = 1;
 331
 332         ret = recvmsg(fd, &msg, 0);
 333         if (ret <= 0)
 334                 goto out;
 335
 336         cmsg = CMSG_FIRSTHDR(&msg);
 337
 338         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 339             cmsg->cmsg_level == SOL_SOCKET &&
 340             cmsg->cmsg_type == SCM_CREDENTIALS) {
 341                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 342                 if (cred.uid &&
 343                     (cred.uid != getuid() || cred.gid != getgid())) {
 344                         INFO("Message denied for '%d/%d'", cred.uid, cred.gid);
 345                         errno = EACCES;
 346                         return -1;
 347                 }
 348         }
 349
 350 out:
 351         return ret;
 352 }
 353
 354 int lxc_unix_sockaddr(struct sockaddr_un *ret, const char *path)
 355 {
 356         size_t len;
 357
 358         len = strlen(path);
 359         if (len == 0)
 360                 return minus_one_set_errno(EINVAL);
 361         if (path[0] != '/' && path[0] != '@')
 362                 return minus_one_set_errno(EINVAL);
 363         if (path[1] == '\0')
 364                 return minus_one_set_errno(EINVAL);
 365
 366         if (len + 1 > sizeof(ret->sun_path))
 367                 return minus_one_set_errno(EINVAL);
 368
 369         *ret = (struct sockaddr_un){
 370             .sun_family = AF_UNIX,
 371         };
 372
 373         if (path[0] == '@') {
 374                 memcpy(ret->sun_path + 1, path + 1, len);
 375                 return (int)(offsetof(struct sockaddr_un, sun_path) + len);
 376         }
 377
 378         memcpy(ret->sun_path, path, len + 1);
 379         return (int)(offsetof(struct sockaddr_un, sun_path) + len + 1);
 380 }
 381
 382 int lxc_unix_connect(struct sockaddr_un *addr)
 383 {
 384         __do_close_prot_errno int fd = -EBADF;
 385         int ret;
 386         ssize_t len;
 387
 388         fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
 389         if (fd < 0) {
 390                 SYSERROR("Failed to open new AF_UNIX socket");
 391                 return -1;
 392         }
 393
 394         if (addr->sun_path[0] == '\0')
 395                 len = strlen(&addr->sun_path[1]);
 396         else
 397                 len = strlen(&addr->sun_path[0]);
 398
 399         ret = connect(fd, (struct sockaddr *)addr,
 400                       offsetof(struct sockaddr_un, sun_path) + len);
 401         if (ret < 0) {
 402                 SYSERROR("Failed to bind new AF_UNIX socket");
 403                 return -1;
 404         }
 405
 406         return move_fd(fd);
 407 }
 408
 409 int lxc_socket_set_timeout(int fd, int rcv_timeout, int snd_timeout)
 410 {
 411         struct timeval out = {0};
 412         int ret;
 413
 414         out.tv_sec = snd_timeout;
 415         ret = setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, (const void *)&out,
 416                          sizeof(out));
 417         if (ret < 0)
 418                 return -1;
 419
 420         out.tv_sec = rcv_timeout;
 421         ret = setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (const void *)&out,
 422                          sizeof(out));
 423         if (ret < 0)
 424                 return -1;
 425
 426         return 0;
 427 }