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 #include "config.h"
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <stddef.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30 #include <fcntl.h>
  31 #include <errno.h>
  32 #include <sys/socket.h>
  33 #include <sys/un.h>
  34
  35 #include "log.h"
  36
  37 lxc_log_define(lxc_af_unix, lxc);
  38
  39 int lxc_abstract_unix_open(const char *path, int type, int flags)
  40 {
  41         int fd;
  42         size_t len;
  43         struct sockaddr_un addr;
  44
  45         fd = socket(PF_UNIX, type, 0);
  46         if (fd < 0)
  47                 return -1;
  48
  49         /* Clear address structure */
  50         memset(&addr, 0, sizeof(addr));
  51
  52         if (!path)
  53                 return fd;
  54
  55         addr.sun_family = AF_UNIX;
  56
  57         len = strlen(&path[1]);
  58         /* do not enforce \0-termination */
  59         if (len >= sizeof(addr.sun_path)) {
  60                 close(fd);
  61                 errno = ENAMETOOLONG;
  62                 return -1;
  63         }
  64         /* addr.sun_path[0] has already been set to 0 by memset() */
  65         strncpy(&addr.sun_path[1], &path[1], strlen(&path[1]));
  66
  67         if (bind(fd, (struct sockaddr *)&addr, offsetof(struct sockaddr_un, sun_path) + len + 1)) {
  68                 int tmp = errno;
  69                 close(fd);
  70                 errno = tmp;
  71                 return -1;
  72         }
  73
  74         if (type == SOCK_STREAM && listen(fd, 100)) {
  75                 int tmp = errno;
  76                 close(fd);
  77                 errno = tmp;
  78                 return -1;
  79         }
  80
  81         return fd;
  82 }
  83
  84 int lxc_abstract_unix_close(int fd)
  85 {
  86         close(fd);
  87
  88         return 0;
  89 }
  90
  91 int lxc_abstract_unix_connect(const char *path)
  92 {
  93         int fd;
  94         size_t len;
  95         struct sockaddr_un addr;
  96
  97         fd = socket(PF_UNIX, SOCK_STREAM, 0);
  98         if (fd < 0)
  99                 return -1;
 100
 101         memset(&addr, 0, sizeof(addr));
 102
 103         addr.sun_family = AF_UNIX;
 104
 105         len = strlen(&path[1]);
 106         /* do not enforce \0-termination */
 107         if (len >= sizeof(addr.sun_path)) {
 108                 close(fd);
 109                 errno = ENAMETOOLONG;
 110                 return -1;
 111         }
 112         /* addr.sun_path[0] has already been set to 0 by memset() */
 113         strncpy(&addr.sun_path[1], &path[1], strlen(&path[1]));
 114
 115         if (connect(fd, (struct sockaddr *)&addr, offsetof(struct sockaddr_un, sun_path) + len + 1)) {
 116                 close(fd);
 117                 return -1;
 118         }
 119
 120         return fd;
 121 }
 122
 123 int lxc_abstract_unix_send_fds(int fd, int *sendfds, int num_sendfds,
 124                                void *data, size_t size)
 125 {
 126         int ret;
 127         struct msghdr msg;
 128         struct iovec iov;
 129         struct cmsghdr *cmsg = NULL;
 130         char buf[1] = {0};
 131         char *cmsgbuf;
 132         size_t cmsgbufsize = CMSG_SPACE(num_sendfds * sizeof(int));
 133
 134         memset(&msg, 0, sizeof(msg));
 135         memset(&iov, 0, sizeof(iov));
 136
 137         cmsgbuf = malloc(cmsgbufsize);
 138         if (!cmsgbuf)
 139                 return -1;
 140
 141         msg.msg_control = cmsgbuf;
 142         msg.msg_controllen = cmsgbufsize;
 143
 144         cmsg = CMSG_FIRSTHDR(&msg);
 145         cmsg->cmsg_level = SOL_SOCKET;
 146         cmsg->cmsg_type = SCM_RIGHTS;
 147         cmsg->cmsg_len = CMSG_LEN(num_sendfds * sizeof(int));
 148
 149         msg.msg_controllen = cmsg->cmsg_len;
 150
 151         memcpy(CMSG_DATA(cmsg), sendfds, num_sendfds * sizeof(int));
 152
 153         iov.iov_base = data ? data : buf;
 154         iov.iov_len = data ? size : sizeof(buf);
 155         msg.msg_iov = &iov;
 156         msg.msg_iovlen = 1;
 157
 158         ret = sendmsg(fd, &msg, MSG_NOSIGNAL);
 159         free(cmsgbuf);
 160         return ret;
 161 }
 162
 163 int lxc_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 164                                void *data, size_t size)
 165 {
 166         int ret;
 167         struct msghdr msg;
 168         struct iovec iov;
 169         struct cmsghdr *cmsg = NULL;
 170         char buf[1] = {0};
 171         char *cmsgbuf;
 172         size_t cmsgbufsize = CMSG_SPACE(num_recvfds * sizeof(int));
 173
 174         memset(&msg, 0, sizeof(msg));
 175         memset(&iov, 0, sizeof(iov));
 176
 177         cmsgbuf = malloc(cmsgbufsize);
 178         if (!cmsgbuf)
 179                 return -1;
 180
 181         msg.msg_control = cmsgbuf;
 182         msg.msg_controllen = cmsgbufsize;
 183
 184         iov.iov_base = data ? data : buf;
 185         iov.iov_len = data ? size : sizeof(buf);
 186         msg.msg_iov = &iov;
 187         msg.msg_iovlen = 1;
 188
 189         ret = recvmsg(fd, &msg, 0);
 190         if (ret <= 0)
 191                 goto out;
 192
 193         cmsg = CMSG_FIRSTHDR(&msg);
 194
 195         memset(recvfds, -1, num_recvfds * sizeof(int));
 196         if (cmsg && cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 197             cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
 198                 memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 199         }
 200
 201 out:
 202         free(cmsgbuf);
 203         return ret;
 204 }
 205
 206 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 207 {
 208         struct msghdr msg = { 0 };
 209         struct iovec iov;
 210         struct cmsghdr *cmsg;
 211         struct ucred cred = {
 212                 .pid = getpid(),
 213                 .uid = getuid(),
 214                 .gid = getgid(),
 215         };
 216         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 217         char buf[1] = {0};
 218
 219         msg.msg_control = cmsgbuf;
 220         msg.msg_controllen = sizeof(cmsgbuf);
 221
 222         cmsg = CMSG_FIRSTHDR(&msg);
 223         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 224         cmsg->cmsg_level = SOL_SOCKET;
 225         cmsg->cmsg_type = SCM_CREDENTIALS;
 226         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 227
 228         msg.msg_name = NULL;
 229         msg.msg_namelen = 0;
 230
 231         iov.iov_base = data ? data : buf;
 232         iov.iov_len = data ? size : sizeof(buf);
 233         msg.msg_iov = &iov;
 234         msg.msg_iovlen = 1;
 235
 236         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 237 }
 238
 239 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 240 {
 241         struct msghdr msg = { 0 };
 242         struct iovec iov;
 243         struct cmsghdr *cmsg;
 244         struct ucred cred;
 245         int ret;
 246         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 247         char buf[1] = {0};
 248
 249         msg.msg_name = NULL;
 250         msg.msg_namelen = 0;
 251         msg.msg_control = cmsgbuf;
 252         msg.msg_controllen = sizeof(cmsgbuf);
 253
 254         iov.iov_base = data ? data : buf;
 255         iov.iov_len = data ? size : sizeof(buf);
 256         msg.msg_iov = &iov;
 257         msg.msg_iovlen = 1;
 258
 259         ret = recvmsg(fd, &msg, 0);
 260         if (ret <= 0)
 261                 goto out;
 262
 263         cmsg = CMSG_FIRSTHDR(&msg);
 264
 265         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 266                         cmsg->cmsg_level == SOL_SOCKET &&
 267                         cmsg->cmsg_type == SCM_CREDENTIALS) {
 268                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 269                 if (cred.uid && (cred.uid != getuid() || cred.gid != getgid())) {
 270                         INFO("message denied for '%d/%d'", cred.uid, cred.gid);
 271                         return -EACCES;
 272                 }
 273         }
 274 out:
 275         return ret;
 276 }