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