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 <errno.h>
  26 #include <fcntl.h>
  27 #include <stddef.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32 #include <sys/socket.h>
  33 #include <sys/syscall.h>
  34 #include <sys/un.h>
  35
  36 #include "log.h"
  37 #include "utils.h"
  38
  39 #ifndef HAVE_STRLCPY
  40 #include "include/strlcpy.h"
  41 #endif
  42
  43 lxc_log_define(af_unix, lxc);
  44
  45 static ssize_t lxc_abstract_unix_set_sockaddr(struct sockaddr_un *addr,
  46                                 const char *path)
  47 {
  48         size_t len;
  49
  50         if (!addr || !path) {
  51                 errno = EINVAL;
  52                 return -1;
  53         }
  54
  55         /* Clear address structure */
  56         memset(addr, 0, sizeof(*addr));
  57
  58         addr->sun_family = AF_UNIX;
  59
  60         len = strlen(&path[1]);
  61
  62         /* do not enforce \0-termination */
  63         if (len >= INT_MAX || len >= sizeof(addr->sun_path)) {
  64                 errno = ENAMETOOLONG;
  65                 return -1;
  66         }
  67
  68         /* do not enforce \0-termination */
  69         memcpy(&addr->sun_path[1], &path[1], len);
  70         return len;
  71 }
  72
  73 int lxc_abstract_unix_open(const char *path, int type, int flags)
  74 {
  75         int fd, ret;
  76         ssize_t len;
  77         struct sockaddr_un addr;
  78
  79         fd = socket(PF_UNIX, type, 0);
  80         if (fd < 0)
  81                 return -1;
  82
  83         if (!path)
  84                 return fd;
  85
  86         len = lxc_abstract_unix_set_sockaddr(&addr, path);
  87         if (len < 0) {
  88                 int saved_errno = errno;
  89                 close(fd);
  90                 errno = saved_errno;
  91                 return -1;
  92         }
  93
  94         ret = bind(fd, (struct sockaddr *)&addr,
  95                    offsetof(struct sockaddr_un, sun_path) + len + 1);
  96         if (ret < 0) {
  97                 int saved_errno = errno;
  98                 close(fd);
  99                 errno = saved_errno;
 100                 return -1;
 101         }
 102
 103         if (type == SOCK_STREAM) {
 104                 ret = listen(fd, 100);
 105                 if (ret < 0) {
 106                         int saved_errno = errno;
 107                         close(fd);
 108                         errno = saved_errno;
 109                         return -1;
 110                 }
 111         }
 112
 113         return fd;
 114 }
 115
 116 void lxc_abstract_unix_close(int fd)
 117 {
 118         close(fd);
 119 }
 120
 121 int lxc_abstract_unix_connect(const char *path)
 122 {
 123         int fd, ret;
 124         ssize_t len;
 125         struct sockaddr_un addr;
 126
 127         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 128         if (fd < 0)
 129                 return -1;
 130
 131         len = lxc_abstract_unix_set_sockaddr(&addr, path);
 132         if (len < 0) {
 133                 int saved_errno = errno;
 134                 close(fd);
 135                 errno = saved_errno;
 136                 return -1;
 137         }
 138
 139         ret = connect(fd, (struct sockaddr *)&addr,
 140                       offsetof(struct sockaddr_un, sun_path) + len + 1);
 141         if (ret < 0) {
 142                 int saved_errno = errno;
 143                 close(fd);
 144                 errno = saved_errno;
 145                 return -1;
 146         }
 147
 148         return fd;
 149 }
 150
 151 int lxc_abstract_unix_send_fds(int fd, int *sendfds, int num_sendfds,
 152                                void *data, size_t size)
 153 {
 154         int ret;
 155         struct msghdr msg;
 156         struct iovec iov;
 157         struct cmsghdr *cmsg = NULL;
 158         char buf[1] = {0};
 159         char *cmsgbuf;
 160         size_t cmsgbufsize = CMSG_SPACE(num_sendfds * sizeof(int));
 161
 162         memset(&msg, 0, sizeof(msg));
 163         memset(&iov, 0, sizeof(iov));
 164
 165         cmsgbuf = malloc(cmsgbufsize);
 166         if (!cmsgbuf) {
 167                 errno = ENOMEM;
 168                 return -1;
 169         }
 170
 171         msg.msg_control = cmsgbuf;
 172         msg.msg_controllen = cmsgbufsize;
 173
 174         cmsg = CMSG_FIRSTHDR(&msg);
 175         cmsg->cmsg_level = SOL_SOCKET;
 176         cmsg->cmsg_type = SCM_RIGHTS;
 177         cmsg->cmsg_len = CMSG_LEN(num_sendfds * sizeof(int));
 178
 179         msg.msg_controllen = cmsg->cmsg_len;
 180
 181         memcpy(CMSG_DATA(cmsg), sendfds, num_sendfds * sizeof(int));
 182
 183         iov.iov_base = data ? data : buf;
 184         iov.iov_len = data ? size : sizeof(buf);
 185         msg.msg_iov = &iov;
 186         msg.msg_iovlen = 1;
 187
 188         ret = sendmsg(fd, &msg, MSG_NOSIGNAL);
 189         free(cmsgbuf);
 190         return ret;
 191 }
 192
 193 int lxc_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 194                                void *data, size_t size)
 195 {
 196         int ret;
 197         struct msghdr msg;
 198         struct iovec iov;
 199         struct cmsghdr *cmsg = NULL;
 200         char buf[1] = {0};
 201         char *cmsgbuf;
 202         size_t cmsgbufsize = CMSG_SPACE(num_recvfds * sizeof(int));
 203
 204         memset(&msg, 0, sizeof(msg));
 205         memset(&iov, 0, sizeof(iov));
 206
 207         cmsgbuf = malloc(cmsgbufsize);
 208         if (!cmsgbuf) {
 209                 errno = ENOMEM;
 210                 return -1;
 211         }
 212
 213         msg.msg_control = cmsgbuf;
 214         msg.msg_controllen = cmsgbufsize;
 215
 216         iov.iov_base = data ? data : buf;
 217         iov.iov_len = data ? size : sizeof(buf);
 218         msg.msg_iov = &iov;
 219         msg.msg_iovlen = 1;
 220
 221         ret = recvmsg(fd, &msg, 0);
 222         if (ret <= 0)
 223                 goto out;
 224
 225         cmsg = CMSG_FIRSTHDR(&msg);
 226
 227         memset(recvfds, -1, num_recvfds * sizeof(int));
 228         if (cmsg && cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 229             cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
 230                 memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 231
 232 out:
 233         free(cmsgbuf);
 234         return ret;
 235 }
 236
 237 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 238 {
 239         struct msghdr msg = {0};
 240         struct iovec iov;
 241         struct cmsghdr *cmsg;
 242         struct ucred cred = {
 243             .pid = lxc_raw_getpid(), .uid = getuid(), .gid = getgid(),
 244         };
 245         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 246         char buf[1] = {0};
 247
 248         msg.msg_control = cmsgbuf;
 249         msg.msg_controllen = sizeof(cmsgbuf);
 250
 251         cmsg = CMSG_FIRSTHDR(&msg);
 252         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 253         cmsg->cmsg_level = SOL_SOCKET;
 254         cmsg->cmsg_type = SCM_CREDENTIALS;
 255         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 256
 257         msg.msg_name = NULL;
 258         msg.msg_namelen = 0;
 259
 260         iov.iov_base = data ? data : buf;
 261         iov.iov_len = data ? size : sizeof(buf);
 262         msg.msg_iov = &iov;
 263         msg.msg_iovlen = 1;
 264
 265         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 266 }
 267
 268 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 269 {
 270         struct msghdr msg = {0};
 271         struct iovec iov;
 272         struct cmsghdr *cmsg;
 273         struct ucred cred;
 274         int ret;
 275         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 276         char buf[1] = {0};
 277
 278         msg.msg_name = NULL;
 279         msg.msg_namelen = 0;
 280         msg.msg_control = cmsgbuf;
 281         msg.msg_controllen = sizeof(cmsgbuf);
 282
 283         iov.iov_base = data ? data : buf;
 284         iov.iov_len = data ? size : sizeof(buf);
 285         msg.msg_iov = &iov;
 286         msg.msg_iovlen = 1;
 287
 288         ret = recvmsg(fd, &msg, 0);
 289         if (ret <= 0)
 290                 goto out;
 291
 292         cmsg = CMSG_FIRSTHDR(&msg);
 293
 294         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 295             cmsg->cmsg_level == SOL_SOCKET &&
 296             cmsg->cmsg_type == SCM_CREDENTIALS) {
 297                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 298                 if (cred.uid &&
 299                     (cred.uid != getuid() || cred.gid != getgid())) {
 300                         INFO("Message denied for '%d/%d'", cred.uid, cred.gid);
 301                         errno = EACCES;
 302                         return -1;
 303                 }
 304         }
 305
 306 out:
 307         return ret;
 308 }