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 #include "lxclock.h"
  34
  35 lxc_log_define(lxc_af_unix, lxc);
  36
  37 int lxc_af_unix_open(const char *path, int type, int flags)
  38 {
  39         int fd;
  40         size_t len;
  41         struct sockaddr_un addr;
  42
  43         if (flags & O_TRUNC)
  44                 unlink(path);
  45
  46         fd = socket(PF_UNIX, type, 0);
  47         if (fd < 0)
  48                 return -1;
  49
  50         memset(&addr, 0, sizeof(addr));
  51
  52         if (!path)
  53                 return fd;
  54
  55         addr.sun_family = AF_UNIX;
  56         /* copy entire buffer in case of abstract socket */
  57         len = sizeof(addr.sun_path);
  58         if (path[0]) {
  59                 len = strlen(path);
  60                 if (len >= sizeof(addr.sun_path)) {
  61                         close(fd);
  62                         errno = ENAMETOOLONG;
  63                         return -1;
  64                 }
  65         }
  66         memcpy(addr.sun_path, path, len);
  67
  68         if (bind(fd, (struct sockaddr *)&addr, sizeof(addr))) {
  69                 int tmp = errno;
  70                 close(fd);
  71                 errno = tmp;
  72                 return -1;
  73         }
  74
  75         if (type == SOCK_STREAM && listen(fd, 100)) {
  76                 int tmp = errno;
  77                 close(fd);
  78                 errno = tmp;
  79                 return -1;
  80         }
  81
  82         return fd;
  83 }
  84
  85 int lxc_af_unix_close(int fd)
  86 {
  87         struct sockaddr_un addr;
  88         socklen_t addrlen = sizeof(addr);
  89
  90         if (!getsockname(fd, (struct sockaddr *)&addr, &addrlen) &&
  91             addr.sun_path[0])
  92                 unlink(addr.sun_path);
  93
  94         close(fd);
  95
  96         return 0;
  97 }
  98
  99 int lxc_af_unix_connect(const char *path)
 100 {
 101         int fd;
 102         struct sockaddr_un addr;
 103
 104         process_lock();
 105         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 106         process_unlock();
 107         if (fd < 0)
 108                 return -1;
 109
 110         memset(&addr, 0, sizeof(addr));
 111
 112         addr.sun_family = AF_UNIX;
 113         /* copy entire buffer in case of abstract socket */
 114         memcpy(addr.sun_path, path,
 115                path[0]?strlen(path):sizeof(addr.sun_path));
 116
 117         if (connect(fd, (struct sockaddr *)&addr, sizeof(addr))) {
 118                 int tmp = errno;
 119                 process_lock();
 120                 close(fd);
 121                 process_unlock();
 122                 errno = tmp;
 123                 return -1;
 124         }
 125
 126         return fd;
 127 }
 128
 129 int lxc_af_unix_send_fd(int fd, int sendfd, void *data, size_t size)
 130 {
 131         struct msghdr msg = { 0 };
 132         struct iovec iov;
 133         struct cmsghdr *cmsg;
 134         char cmsgbuf[CMSG_SPACE(sizeof(int))];
 135         char buf[1];
 136         int *val;
 137
 138         msg.msg_control = cmsgbuf;
 139         msg.msg_controllen = sizeof(cmsgbuf);
 140
 141         cmsg = CMSG_FIRSTHDR(&msg);
 142         cmsg->cmsg_len = CMSG_LEN(sizeof(int));
 143         cmsg->cmsg_level = SOL_SOCKET;
 144         cmsg->cmsg_type = SCM_RIGHTS;
 145         val = (int *)(CMSG_DATA(cmsg));
 146         *val = sendfd;
 147
 148         msg.msg_name = NULL;
 149         msg.msg_namelen = 0;
 150
 151         iov.iov_base = data ? data : buf;
 152         iov.iov_len = data ? size : sizeof(buf);
 153         msg.msg_iov = &iov;
 154         msg.msg_iovlen = 1;
 155
 156         return sendmsg(fd, &msg, 0);
 157 }
 158
 159 int lxc_af_unix_recv_fd(int fd, int *recvfd, void *data, size_t size)
 160 {
 161         struct msghdr msg = { 0 };
 162         struct iovec iov;
 163         struct cmsghdr *cmsg;
 164         char cmsgbuf[CMSG_SPACE(sizeof(int))];
 165         char buf[1];
 166         int ret, *val;
 167
 168         msg.msg_name = NULL;
 169         msg.msg_namelen = 0;
 170         msg.msg_control = cmsgbuf;
 171         msg.msg_controllen = sizeof(cmsgbuf);
 172
 173         iov.iov_base = data ? data : buf;
 174         iov.iov_len = data ? size : sizeof(buf);
 175         msg.msg_iov = &iov;
 176         msg.msg_iovlen = 1;
 177
 178         ret = recvmsg(fd, &msg, 0);
 179         if (ret <= 0)
 180                 goto out;
 181
 182         cmsg = CMSG_FIRSTHDR(&msg);
 183
 184         /* if the message is wrong the variable will not be
 185          * filled and the peer will notified about a problem */
 186         *recvfd = -1;
 187
 188         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(int)) &&
 189             cmsg->cmsg_level == SOL_SOCKET &&
 190             cmsg->cmsg_type == SCM_RIGHTS) {
 191                 val = (int *) CMSG_DATA(cmsg);
 192                 *recvfd = *val;
 193         }
 194 out:
 195         return ret;
 196 }
 197
 198 int lxc_af_unix_send_credential(int fd, void *data, size_t size)
 199 {
 200         struct msghdr msg = { 0 };
 201         struct iovec iov;
 202         struct cmsghdr *cmsg;
 203         struct ucred cred = {
 204                 .pid = getpid(),
 205                 .uid = getuid(),
 206                 .gid = getgid(),
 207         };
 208         char cmsgbuf[CMSG_SPACE(sizeof(cred))];
 209         char buf[1];
 210
 211         msg.msg_control = cmsgbuf;
 212         msg.msg_controllen = sizeof(cmsgbuf);
 213
 214         cmsg = CMSG_FIRSTHDR(&msg);
 215         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 216         cmsg->cmsg_level = SOL_SOCKET;
 217         cmsg->cmsg_type = SCM_CREDENTIALS;
 218         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 219
 220         msg.msg_name = NULL;
 221         msg.msg_namelen = 0;
 222
 223         iov.iov_base = data ? data : buf;
 224         iov.iov_len = data ? size : sizeof(buf);
 225         msg.msg_iov = &iov;
 226         msg.msg_iovlen = 1;
 227
 228         return sendmsg(fd, &msg, 0);
 229 }
 230
 231 int lxc_af_unix_rcv_credential(int fd, void *data, size_t size)
 232 {
 233         struct msghdr msg = { 0 };
 234         struct iovec iov;
 235         struct cmsghdr *cmsg;
 236         struct ucred cred;
 237         char cmsgbuf[CMSG_SPACE(sizeof(cred))];
 238         char buf[1];
 239         int ret;
 240
 241         msg.msg_name = NULL;
 242         msg.msg_namelen = 0;
 243         msg.msg_control = cmsgbuf;
 244         msg.msg_controllen = sizeof(cmsgbuf);
 245
 246         iov.iov_base = data ? data : buf;
 247         iov.iov_len = data ? size : sizeof(buf);
 248         msg.msg_iov = &iov;
 249         msg.msg_iovlen = 1;
 250
 251         ret = recvmsg(fd, &msg, 0);
 252         if (ret <= 0)
 253                 goto out;
 254
 255         cmsg = CMSG_FIRSTHDR(&msg);
 256
 257         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 258             cmsg->cmsg_level == SOL_SOCKET &&
 259             cmsg->cmsg_type == SCM_CREDENTIALS) {
 260                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 261                 if (cred.uid && (cred.uid != getuid() || cred.gid != getgid())) {
 262                         INFO("message denied for '%d/%d'", cred.uid, cred.gid);
 263                         return -EACCES;
 264                 }
 265         }
 266 out:
 267         return ret;
 268 }