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, ret;
  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], len);
  66
  67         ret = bind(fd, (struct sockaddr *)&addr,
  68                    offsetof(struct sockaddr_un, sun_path) + len + 1);
  69         if (ret < 0) {
  70                 int tmp = errno;
  71                 close(fd);
  72                 errno = tmp;
  73                 return -1;
  74         }
  75
  76         if (type == SOCK_STREAM) {
  77                 ret = listen(fd, 100);
  78                 if (ret < 0) {
  79                         int tmp = errno;
  80                         close(fd);
  81                         errno = tmp;
  82                         return -1;
  83                 }
  84
  85         }
  86
  87         return fd;
  88 }
  89
  90 int lxc_abstract_unix_close(int fd)
  91 {
  92         close(fd);
  93         return 0;
  94 }
  95
  96 int lxc_abstract_unix_connect(const char *path)
  97 {
  98         int fd, ret;
  99         size_t len;
 100         struct sockaddr_un addr;
 101
 102         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 103         if (fd < 0)
 104                 return -1;
 105
 106         memset(&addr, 0, sizeof(addr));
 107
 108         addr.sun_family = AF_UNIX;
 109
 110         len = strlen(&path[1]);
 111         /* do not enforce \0-termination */
 112         if (len >= sizeof(addr.sun_path)) {
 113                 close(fd);
 114                 errno = ENAMETOOLONG;
 115                 return -1;
 116         }
 117         /* addr.sun_path[0] has already been set to 0 by memset() */
 118         strncpy(&addr.sun_path[1], &path[1], strlen(&path[1]));
 119
 120         ret = connect(fd, (struct sockaddr *)&addr,
 121                       offsetof(struct sockaddr_un, sun_path) + len + 1);
 122         if (ret < 0) {
 123                 close(fd);
 124                 return -1;
 125         }
 126
 127         return fd;
 128 }
 129
 130 int lxc_abstract_unix_send_fds(int fd, int *sendfds, int num_sendfds,
 131                                void *data, size_t size)
 132 {
 133         int ret;
 134         struct msghdr msg;
 135         struct iovec iov;
 136         struct cmsghdr *cmsg = NULL;
 137         char buf[1] = {0};
 138         char *cmsgbuf;
 139         size_t cmsgbufsize = CMSG_SPACE(num_sendfds * sizeof(int));
 140
 141         memset(&msg, 0, sizeof(msg));
 142         memset(&iov, 0, sizeof(iov));
 143
 144         cmsgbuf = malloc(cmsgbufsize);
 145         if (!cmsgbuf)
 146                 return -1;
 147
 148         msg.msg_control = cmsgbuf;
 149         msg.msg_controllen = cmsgbufsize;
 150
 151         cmsg = CMSG_FIRSTHDR(&msg);
 152         cmsg->cmsg_level = SOL_SOCKET;
 153         cmsg->cmsg_type = SCM_RIGHTS;
 154         cmsg->cmsg_len = CMSG_LEN(num_sendfds * sizeof(int));
 155
 156         msg.msg_controllen = cmsg->cmsg_len;
 157
 158         memcpy(CMSG_DATA(cmsg), sendfds, num_sendfds * sizeof(int));
 159
 160         iov.iov_base = data ? data : buf;
 161         iov.iov_len = data ? size : sizeof(buf);
 162         msg.msg_iov = &iov;
 163         msg.msg_iovlen = 1;
 164
 165         ret = sendmsg(fd, &msg, MSG_NOSIGNAL);
 166         free(cmsgbuf);
 167         return ret;
 168 }
 169
 170 int lxc_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 171                                void *data, size_t size)
 172 {
 173         int ret;
 174         struct msghdr msg;
 175         struct iovec iov;
 176         struct cmsghdr *cmsg = NULL;
 177         char buf[1] = {0};
 178         char *cmsgbuf;
 179         size_t cmsgbufsize = CMSG_SPACE(num_recvfds * sizeof(int));
 180
 181         memset(&msg, 0, sizeof(msg));
 182         memset(&iov, 0, sizeof(iov));
 183
 184         cmsgbuf = malloc(cmsgbufsize);
 185         if (!cmsgbuf)
 186                 return -1;
 187
 188         msg.msg_control = cmsgbuf;
 189         msg.msg_controllen = cmsgbufsize;
 190
 191         iov.iov_base = data ? data : buf;
 192         iov.iov_len = data ? size : sizeof(buf);
 193         msg.msg_iov = &iov;
 194         msg.msg_iovlen = 1;
 195
 196         ret = recvmsg(fd, &msg, 0);
 197         if (ret <= 0)
 198                 goto out;
 199
 200         cmsg = CMSG_FIRSTHDR(&msg);
 201
 202         memset(recvfds, -1, num_recvfds * sizeof(int));
 203         if (cmsg && cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 204             cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
 205                 memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 206         }
 207
 208 out:
 209         free(cmsgbuf);
 210         return ret;
 211 }
 212
 213 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 214 {
 215         struct msghdr msg = {0};
 216         struct iovec iov;
 217         struct cmsghdr *cmsg;
 218         struct ucred cred = {
 219             .pid = getpid(), .uid = getuid(), .gid = getgid(),
 220         };
 221         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 222         char buf[1] = {0};
 223
 224         msg.msg_control = cmsgbuf;
 225         msg.msg_controllen = sizeof(cmsgbuf);
 226
 227         cmsg = CMSG_FIRSTHDR(&msg);
 228         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 229         cmsg->cmsg_level = SOL_SOCKET;
 230         cmsg->cmsg_type = SCM_CREDENTIALS;
 231         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 232
 233         msg.msg_name = NULL;
 234         msg.msg_namelen = 0;
 235
 236         iov.iov_base = data ? data : buf;
 237         iov.iov_len = data ? size : sizeof(buf);
 238         msg.msg_iov = &iov;
 239         msg.msg_iovlen = 1;
 240
 241         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 242 }
 243
 244 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 245 {
 246         struct msghdr msg = {0};
 247         struct iovec iov;
 248         struct cmsghdr *cmsg;
 249         struct ucred cred;
 250         int ret;
 251         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 252         char buf[1] = {0};
 253
 254         msg.msg_name = NULL;
 255         msg.msg_namelen = 0;
 256         msg.msg_control = cmsgbuf;
 257         msg.msg_controllen = sizeof(cmsgbuf);
 258
 259         iov.iov_base = data ? data : buf;
 260         iov.iov_len = data ? size : sizeof(buf);
 261         msg.msg_iov = &iov;
 262         msg.msg_iovlen = 1;
 263
 264         ret = recvmsg(fd, &msg, 0);
 265         if (ret <= 0)
 266                 goto out;
 267
 268         cmsg = CMSG_FIRSTHDR(&msg);
 269
 270         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 271             cmsg->cmsg_level == SOL_SOCKET &&
 272             cmsg->cmsg_type == SCM_CREDENTIALS) {
 273                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 274                 if (cred.uid &&
 275                     (cred.uid != getuid() || cred.gid != getgid())) {
 276                         INFO("message denied for '%d/%d'", cred.uid, cred.gid);
 277                         return -EACCES;
 278                 }
 279         }
 280 out:
 281         return ret;
 282 }