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 <string.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <errno.h>
  27 #define __USE_GNU
  28 #include <sys/socket.h>
  29 #undef __USE_GNU
  30 #include <sys/un.h>
  31
  32 #include "log.h"
  33
  34 lxc_log_define(lxc_af_unix, lxc);
  35
  36 int lxc_af_unix_open(const char *path, int type, int flags)
  37 {
  38         int fd;
  39         size_t len;
  40         struct sockaddr_un addr;
  41
  42         if (flags & O_TRUNC)
  43                 unlink(path);
  44
  45         fd = socket(PF_UNIX, type, 0);
  46         if (fd < 0)
  47                 return -1;
  48
  49         memset(&addr, 0, sizeof(addr));
  50
  51         if (!path)
  52                 return fd;
  53
  54         addr.sun_family = AF_UNIX;
  55         /* copy entire buffer in case of abstract socket */
  56         len = sizeof(addr.sun_path);
  57         if (path[0]) {
  58                 len = strlen(path);
  59                 if (len >= sizeof(addr.sun_path)) {
  60                         close(fd);
  61                         errno = ENAMETOOLONG;
  62                         return -1;
  63                 }
  64         }
  65         memcpy(addr.sun_path, path, len);
  66
  67         if (bind(fd, (struct sockaddr *)&addr, sizeof(addr))) {
  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_af_unix_close(int fd)
  85 {
  86         struct sockaddr_un addr;
  87         socklen_t addrlen = sizeof(addr);
  88
  89         if (!getsockname(fd, (struct sockaddr *)&addr, &addrlen) &&
  90             addr.sun_path[0])
  91                 unlink(addr.sun_path);
  92
  93         close(fd);
  94
  95         return 0;
  96 }
  97
  98 int lxc_af_unix_connect(const char *path)
  99 {
 100         int fd;
 101         struct sockaddr_un addr;
 102
 103         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 104         if (fd < 0)
 105                 return -1;
 106
 107         memset(&addr, 0, sizeof(addr));
 108
 109         addr.sun_family = AF_UNIX;
 110         /* copy entire buffer in case of abstract socket */
 111         memcpy(addr.sun_path, path,
 112                path[0]?strlen(path):sizeof(addr.sun_path));
 113
 114         if (connect(fd, (struct sockaddr *)&addr, sizeof(addr))) {
 115                 int tmp = errno;
 116                 close(fd);
 117                 errno = tmp;
 118                 return -1;
 119         }
 120
 121         return fd;
 122 }
 123
 124 int lxc_af_unix_send_fd(int fd, int sendfd, void *data, size_t size)
 125 {
 126         struct msghdr msg = { 0 };
 127         struct iovec iov;
 128         struct cmsghdr *cmsg;
 129         char cmsgbuf[CMSG_SPACE(sizeof(int))];
 130         char buf[1];
 131         int *val;
 132
 133         msg.msg_control = cmsgbuf;
 134         msg.msg_controllen = sizeof(cmsgbuf);
 135
 136         cmsg = CMSG_FIRSTHDR(&msg);
 137         cmsg->cmsg_len = CMSG_LEN(sizeof(int));
 138         cmsg->cmsg_level = SOL_SOCKET;
 139         cmsg->cmsg_type = SCM_RIGHTS;
 140         val = (int *)(CMSG_DATA(cmsg));
 141         *val = sendfd;
 142
 143         msg.msg_name = NULL;
 144         msg.msg_namelen = 0;
 145
 146         iov.iov_base = data ? data : buf;
 147         iov.iov_len = data ? size : sizeof(buf);
 148         msg.msg_iov = &iov;
 149         msg.msg_iovlen = 1;
 150
 151         return sendmsg(fd, &msg, 0);
 152 }
 153
 154 int lxc_af_unix_recv_fd(int fd, int *recvfd, void *data, size_t size)
 155 {
 156         struct msghdr msg = { 0 };
 157         struct iovec iov;
 158         struct cmsghdr *cmsg;
 159         char cmsgbuf[CMSG_SPACE(sizeof(int))];
 160         char buf[1];
 161         int ret, *val;
 162
 163         msg.msg_name = NULL;
 164         msg.msg_namelen = 0;
 165         msg.msg_control = cmsgbuf;
 166         msg.msg_controllen = sizeof(cmsgbuf);
 167
 168         iov.iov_base = data ? data : buf;
 169         iov.iov_len = data ? size : sizeof(buf);
 170         msg.msg_iov = &iov;
 171         msg.msg_iovlen = 1;
 172
 173         ret = recvmsg(fd, &msg, 0);
 174         if (ret <= 0)
 175                 goto out;
 176
 177         cmsg = CMSG_FIRSTHDR(&msg);
 178
 179         /* if the message is wrong the variable will not be
 180          * filled and the peer will notified about a problem */
 181         *recvfd = -1;
 182
 183         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(int)) &&
 184             cmsg->cmsg_level == SOL_SOCKET &&
 185             cmsg->cmsg_type == SCM_RIGHTS) {
 186                 val = (int *) CMSG_DATA(cmsg);
 187                 *recvfd = *val;
 188         }
 189 out:
 190         return ret;
 191 }
 192
 193 int lxc_af_unix_send_credential(int fd, void *data, size_t size)
 194 {
 195         struct msghdr msg = { 0 };
 196         struct iovec iov;
 197         struct cmsghdr *cmsg;
 198         struct ucred cred = {
 199                 .pid = getpid(),
 200                 .uid = getuid(),
 201                 .gid = getgid(),
 202         };
 203         char cmsgbuf[CMSG_SPACE(sizeof(cred))];
 204         char buf[1];
 205
 206         msg.msg_control = cmsgbuf;
 207         msg.msg_controllen = sizeof(cmsgbuf);
 208
 209         cmsg = CMSG_FIRSTHDR(&msg);
 210         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 211         cmsg->cmsg_level = SOL_SOCKET;
 212         cmsg->cmsg_type = SCM_CREDENTIALS;
 213         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 214
 215         msg.msg_name = NULL;
 216         msg.msg_namelen = 0;
 217
 218         iov.iov_base = data ? data : buf;
 219         iov.iov_len = data ? size : sizeof(buf);
 220         msg.msg_iov = &iov;
 221         msg.msg_iovlen = 1;
 222
 223         return sendmsg(fd, &msg, 0);
 224 }
 225
 226 int lxc_af_unix_rcv_credential(int fd, void *data, size_t size)
 227 {
 228         struct msghdr msg = { 0 };
 229         struct iovec iov;
 230         struct cmsghdr *cmsg;
 231         struct ucred cred;
 232         char cmsgbuf[CMSG_SPACE(sizeof(cred))];
 233         char buf[1];
 234         int ret;
 235
 236         msg.msg_name = NULL;
 237         msg.msg_namelen = 0;
 238         msg.msg_control = cmsgbuf;
 239         msg.msg_controllen = sizeof(cmsgbuf);
 240
 241         iov.iov_base = data ? data : buf;
 242         iov.iov_len = data ? size : sizeof(buf);
 243         msg.msg_iov = &iov;
 244         msg.msg_iovlen = 1;
 245
 246         ret = recvmsg(fd, &msg, 0);
 247         if (ret <= 0)
 248                 goto out;
 249
 250         cmsg = CMSG_FIRSTHDR(&msg);
 251
 252         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 253             cmsg->cmsg_level == SOL_SOCKET &&
 254             cmsg->cmsg_type == SCM_CREDENTIALS) {
 255                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 256                 if (cred.uid && (cred.uid != getuid() || cred.gid != getgid())) {
 257                         INFO("message denied for '%d/%d'", cred.uid, cred.gid);
 258                         return -EACCES;
 259                 }
 260         }
 261 out:
 262         return ret;
 263 }