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 "utils.h"
  41
  42 #ifndef HAVE_STRLCPY
  43 #include "include/strlcpy.h"
  44 #endif
  45
  46 lxc_log_define(af_unix, lxc);
  47
  48 static ssize_t lxc_abstract_unix_set_sockaddr(struct sockaddr_un *addr,
  49                                 const char *path)
  50 {
  51         size_t len;
  52
  53         if (!addr || !path) {
  54                 errno = EINVAL;
  55                 return -1;
  56         }
  57
  58         /* Clear address structure */
  59         memset(addr, 0, sizeof(*addr));
  60
  61         addr->sun_family = AF_UNIX;
  62
  63         len = strlen(&path[1]);
  64
  65         /* do not enforce \0-termination */
  66         if (len >= INT_MAX || len >= sizeof(addr->sun_path)) {
  67                 errno = ENAMETOOLONG;
  68                 return -1;
  69         }
  70
  71         /* do not enforce \0-termination */
  72         memcpy(&addr->sun_path[1], &path[1], len);
  73         return len;
  74 }
  75
  76 int lxc_abstract_unix_open(const char *path, int type, int flags)
  77 {
  78         int fd, ret;
  79         ssize_t len;
  80         struct sockaddr_un addr;
  81
  82         fd = socket(PF_UNIX, type, 0);
  83         if (fd < 0)
  84                 return -1;
  85
  86         if (!path)
  87                 return fd;
  88
  89         len = lxc_abstract_unix_set_sockaddr(&addr, path);
  90         if (len < 0) {
  91                 int saved_errno = errno;
  92                 close(fd);
  93                 errno = saved_errno;
  94                 return -1;
  95         }
  96
  97         ret = bind(fd, (struct sockaddr *)&addr,
  98                    offsetof(struct sockaddr_un, sun_path) + len + 1);
  99         if (ret < 0) {
 100                 int saved_errno = errno;
 101                 close(fd);
 102                 errno = saved_errno;
 103                 return -1;
 104         }
 105
 106         if (type == SOCK_STREAM) {
 107                 ret = listen(fd, 100);
 108                 if (ret < 0) {
 109                         int saved_errno = errno;
 110                         close(fd);
 111                         errno = saved_errno;
 112                         return -1;
 113                 }
 114         }
 115
 116         return fd;
 117 }
 118
 119 void lxc_abstract_unix_close(int fd)
 120 {
 121         close(fd);
 122 }
 123
 124 int lxc_abstract_unix_connect(const char *path)
 125 {
 126         int fd, ret;
 127         ssize_t len;
 128         struct sockaddr_un addr;
 129
 130         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 131         if (fd < 0)
 132                 return -1;
 133
 134         len = lxc_abstract_unix_set_sockaddr(&addr, path);
 135         if (len < 0) {
 136                 int saved_errno = errno;
 137                 close(fd);
 138                 errno = saved_errno;
 139                 return -1;
 140         }
 141
 142         ret = connect(fd, (struct sockaddr *)&addr,
 143                       offsetof(struct sockaddr_un, sun_path) + len + 1);
 144         if (ret < 0) {
 145                 int saved_errno = errno;
 146                 close(fd);
 147                 errno = saved_errno;
 148                 return -1;
 149         }
 150
 151         return fd;
 152 }
 153
 154 int lxc_abstract_unix_send_fds(int fd, int *sendfds, int num_sendfds,
 155                                void *data, size_t size)
 156 {
 157         int ret;
 158         struct msghdr msg;
 159         struct iovec iov;
 160         struct cmsghdr *cmsg = NULL;
 161         char buf[1] = {0};
 162         char *cmsgbuf;
 163         size_t cmsgbufsize = CMSG_SPACE(num_sendfds * sizeof(int));
 164
 165         memset(&msg, 0, sizeof(msg));
 166         memset(&iov, 0, sizeof(iov));
 167
 168         cmsgbuf = malloc(cmsgbufsize);
 169         if (!cmsgbuf) {
 170                 errno = ENOMEM;
 171                 return -1;
 172         }
 173
 174         msg.msg_control = cmsgbuf;
 175         msg.msg_controllen = cmsgbufsize;
 176
 177         cmsg = CMSG_FIRSTHDR(&msg);
 178         cmsg->cmsg_level = SOL_SOCKET;
 179         cmsg->cmsg_type = SCM_RIGHTS;
 180         cmsg->cmsg_len = CMSG_LEN(num_sendfds * sizeof(int));
 181
 182         msg.msg_controllen = cmsg->cmsg_len;
 183
 184         memcpy(CMSG_DATA(cmsg), sendfds, num_sendfds * sizeof(int));
 185
 186         iov.iov_base = data ? data : buf;
 187         iov.iov_len = data ? size : sizeof(buf);
 188         msg.msg_iov = &iov;
 189         msg.msg_iovlen = 1;
 190
 191         ret = sendmsg(fd, &msg, MSG_NOSIGNAL);
 192         free(cmsgbuf);
 193         return ret;
 194 }
 195
 196 int lxc_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 197                                void *data, size_t size)
 198 {
 199         int ret;
 200         struct msghdr msg;
 201         struct iovec iov;
 202         struct cmsghdr *cmsg = NULL;
 203         char buf[1] = {0};
 204         char *cmsgbuf;
 205         size_t cmsgbufsize = CMSG_SPACE(num_recvfds * sizeof(int));
 206
 207         memset(&msg, 0, sizeof(msg));
 208         memset(&iov, 0, sizeof(iov));
 209
 210         cmsgbuf = malloc(cmsgbufsize);
 211         if (!cmsgbuf) {
 212                 errno = ENOMEM;
 213                 return -1;
 214         }
 215
 216         msg.msg_control = cmsgbuf;
 217         msg.msg_controllen = cmsgbufsize;
 218
 219         iov.iov_base = data ? data : buf;
 220         iov.iov_len = data ? size : sizeof(buf);
 221         msg.msg_iov = &iov;
 222         msg.msg_iovlen = 1;
 223
 224         ret = recvmsg(fd, &msg, 0);
 225         if (ret <= 0)
 226                 goto out;
 227
 228         cmsg = CMSG_FIRSTHDR(&msg);
 229
 230         memset(recvfds, -1, num_recvfds * sizeof(int));
 231         if (cmsg && cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 232             cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
 233                 memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 234
 235 out:
 236         free(cmsgbuf);
 237         return ret;
 238 }
 239
 240 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 241 {
 242         struct msghdr msg = {0};
 243         struct iovec iov;
 244         struct cmsghdr *cmsg;
 245         struct ucred cred = {
 246             .pid = lxc_raw_getpid(), .uid = getuid(), .gid = getgid(),
 247         };
 248         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 249         char buf[1] = {0};
 250
 251         msg.msg_control = cmsgbuf;
 252         msg.msg_controllen = sizeof(cmsgbuf);
 253
 254         cmsg = CMSG_FIRSTHDR(&msg);
 255         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 256         cmsg->cmsg_level = SOL_SOCKET;
 257         cmsg->cmsg_type = SCM_CREDENTIALS;
 258         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 259
 260         msg.msg_name = NULL;
 261         msg.msg_namelen = 0;
 262
 263         iov.iov_base = data ? data : buf;
 264         iov.iov_len = data ? size : sizeof(buf);
 265         msg.msg_iov = &iov;
 266         msg.msg_iovlen = 1;
 267
 268         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 269 }
 270
 271 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 272 {
 273         struct msghdr msg = {0};
 274         struct iovec iov;
 275         struct cmsghdr *cmsg;
 276         struct ucred cred;
 277         int ret;
 278         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 279         char buf[1] = {0};
 280
 281         msg.msg_name = NULL;
 282         msg.msg_namelen = 0;
 283         msg.msg_control = cmsgbuf;
 284         msg.msg_controllen = sizeof(cmsgbuf);
 285
 286         iov.iov_base = data ? data : buf;
 287         iov.iov_len = data ? size : sizeof(buf);
 288         msg.msg_iov = &iov;
 289         msg.msg_iovlen = 1;
 290
 291         ret = recvmsg(fd, &msg, 0);
 292         if (ret <= 0)
 293                 goto out;
 294
 295         cmsg = CMSG_FIRSTHDR(&msg);
 296
 297         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 298             cmsg->cmsg_level == SOL_SOCKET &&
 299             cmsg->cmsg_type == SCM_CREDENTIALS) {
 300                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 301                 if (cred.uid &&
 302                     (cred.uid != getuid() || cred.gid != getgid())) {
 303                         INFO("Message denied for '%d/%d'", cred.uid, cred.gid);
 304                         errno = EACCES;
 305                         return -1;
 306                 }
 307         }
 308
 309 out:
 310         return ret;
 311 }