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
  24 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE 1
  26 #endif
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <stddef.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34 #include <sys/socket.h>
  35 #include <sys/syscall.h>
  36 #include <sys/un.h>
  37
  38 #include "config.h"
  39 #include "log.h"
  40 #include "memory_utils.h"
  41 #include "raw_syscalls.h"
  42 #include "utils.h"
  43
  44 #ifndef HAVE_STRLCPY
  45 #include "include/strlcpy.h"
  46 #endif
  47
  48 lxc_log_define(af_unix, lxc);
  49
  50 static ssize_t lxc_abstract_unix_set_sockaddr(struct sockaddr_un *addr,
  51                                 const char *path)
  52 {
  53         size_t len;
  54
  55         if (!addr || !path) {
  56                 errno = EINVAL;
  57                 return -1;
  58         }
  59
  60         /* Clear address structure */
  61         memset(addr, 0, sizeof(*addr));
  62
  63         addr->sun_family = AF_UNIX;
  64
  65         len = strlen(&path[1]);
  66
  67         /* do not enforce \0-termination */
  68         if (len >= INT_MAX || len >= sizeof(addr->sun_path)) {
  69                 errno = ENAMETOOLONG;
  70                 return -1;
  71         }
  72
  73         /* do not enforce \0-termination */
  74         memcpy(&addr->sun_path[1], &path[1], len);
  75         return len;
  76 }
  77
  78 int lxc_abstract_unix_open(const char *path, int type, int flags)
  79 {
  80         int fd, ret;
  81         ssize_t len;
  82         struct sockaddr_un addr;
  83
  84         fd = socket(PF_UNIX, type, 0);
  85         if (fd < 0)
  86                 return -1;
  87
  88         if (!path)
  89                 return fd;
  90
  91         len = lxc_abstract_unix_set_sockaddr(&addr, path);
  92         if (len < 0) {
  93                 int saved_errno = errno;
  94                 close(fd);
  95                 errno = saved_errno;
  96                 return -1;
  97         }
  98
  99         ret = bind(fd, (struct sockaddr *)&addr,
 100                    offsetof(struct sockaddr_un, sun_path) + len + 1);
 101         if (ret < 0) {
 102                 int saved_errno = errno;
 103                 close(fd);
 104                 errno = saved_errno;
 105                 return -1;
 106         }
 107
 108         if (type == SOCK_STREAM) {
 109                 ret = listen(fd, 100);
 110                 if (ret < 0) {
 111                         int saved_errno = errno;
 112                         close(fd);
 113                         errno = saved_errno;
 114                         return -1;
 115                 }
 116         }
 117
 118         return fd;
 119 }
 120
 121 void lxc_abstract_unix_close(int fd)
 122 {
 123         close(fd);
 124 }
 125
 126 int lxc_abstract_unix_connect(const char *path)
 127 {
 128         int fd, ret;
 129         ssize_t len;
 130         struct sockaddr_un addr;
 131
 132         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 133         if (fd < 0)
 134                 return -1;
 135
 136         len = lxc_abstract_unix_set_sockaddr(&addr, path);
 137         if (len < 0) {
 138                 int saved_errno = errno;
 139                 close(fd);
 140                 errno = saved_errno;
 141                 return -1;
 142         }
 143
 144         ret = connect(fd, (struct sockaddr *)&addr,
 145                       offsetof(struct sockaddr_un, sun_path) + len + 1);
 146         if (ret < 0) {
 147                 int saved_errno = errno;
 148                 close(fd);
 149                 errno = saved_errno;
 150                 return -1;
 151         }
 152
 153         return fd;
 154 }
 155
 156 int lxc_abstract_unix_send_fds(int fd, int *sendfds, int num_sendfds,
 157                                void *data, size_t size)
 158 {
 159         __do_free char *cmsgbuf;
 160         struct msghdr msg;
 161         struct iovec iov;
 162         struct cmsghdr *cmsg = NULL;
 163         char buf[1] = {0};
 164         size_t cmsgbufsize = CMSG_SPACE(num_sendfds * sizeof(int));
 165
 166         memset(&msg, 0, sizeof(msg));
 167         memset(&iov, 0, sizeof(iov));
 168
 169         cmsgbuf = malloc(cmsgbufsize);
 170         if (!cmsgbuf) {
 171                 errno = ENOMEM;
 172                 return -1;
 173         }
 174
 175         msg.msg_control = cmsgbuf;
 176         msg.msg_controllen = cmsgbufsize;
 177
 178         cmsg = CMSG_FIRSTHDR(&msg);
 179         cmsg->cmsg_level = SOL_SOCKET;
 180         cmsg->cmsg_type = SCM_RIGHTS;
 181         cmsg->cmsg_len = CMSG_LEN(num_sendfds * sizeof(int));
 182
 183         msg.msg_controllen = cmsg->cmsg_len;
 184
 185         memcpy(CMSG_DATA(cmsg), sendfds, num_sendfds * sizeof(int));
 186
 187         iov.iov_base = data ? data : buf;
 188         iov.iov_len = data ? size : sizeof(buf);
 189         msg.msg_iov = &iov;
 190         msg.msg_iovlen = 1;
 191
 192         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 193 }
 194
 195 int lxc_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 196                                void *data, size_t size)
 197 {
 198         __do_free char *cmsgbuf;
 199         int ret;
 200         struct msghdr msg;
 201         struct iovec iov;
 202         struct cmsghdr *cmsg = NULL;
 203         char buf[1] = {0};
 204         size_t cmsgbufsize = CMSG_SPACE(sizeof(struct ucred)) +
 205                              CMSG_SPACE(num_recvfds * sizeof(int));
 206
 207         memset(&msg, 0, sizeof(msg));
 208         memset(&iov, 0, sizeof(iov));
 209
 210         cmsgbuf = malloc(cmsgbufsize);
 211         if (!cmsgbuf) {
 212                 errno = ENOMEM;
 213                 return -1;
 214         }
 215
 216         msg.msg_control = cmsgbuf;
 217         msg.msg_controllen = cmsgbufsize;
 218
 219         iov.iov_base = data ? data : buf;
 220         iov.iov_len = data ? size : sizeof(buf);
 221         msg.msg_iov = &iov;
 222         msg.msg_iovlen = 1;
 223
 224         ret = recvmsg(fd, &msg, 0);
 225         if (ret <= 0)
 226                 goto out;
 227
 228         /*
 229          * If SO_PASSCRED is set we will always get a ucred message.
 230          */
 231         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 232                 if (cmsg->cmsg_type != SCM_RIGHTS)
 233                         continue;
 234
 235                 memset(recvfds, -1, num_recvfds * sizeof(int));
 236                 if (cmsg &&
 237                     cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 238                     cmsg->cmsg_level == SOL_SOCKET)
 239                         memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 240                 break;
 241         }
 242
 243 out:
 244         return ret;
 245 }
 246
 247 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 248 {
 249         struct msghdr msg = {0};
 250         struct iovec iov;
 251         struct cmsghdr *cmsg;
 252         struct ucred cred = {
 253             .pid = lxc_raw_getpid(), .uid = getuid(), .gid = getgid(),
 254         };
 255         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 256         char buf[1] = {0};
 257
 258         msg.msg_control = cmsgbuf;
 259         msg.msg_controllen = sizeof(cmsgbuf);
 260
 261         cmsg = CMSG_FIRSTHDR(&msg);
 262         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 263         cmsg->cmsg_level = SOL_SOCKET;
 264         cmsg->cmsg_type = SCM_CREDENTIALS;
 265         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 266
 267         msg.msg_name = NULL;
 268         msg.msg_namelen = 0;
 269
 270         iov.iov_base = data ? data : buf;
 271         iov.iov_len = data ? size : sizeof(buf);
 272         msg.msg_iov = &iov;
 273         msg.msg_iovlen = 1;
 274
 275         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 276 }
 277
 278 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 279 {
 280         struct msghdr msg = {0};
 281         struct iovec iov;
 282         struct cmsghdr *cmsg;
 283         struct ucred cred;
 284         int ret;
 285         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 286         char buf[1] = {0};
 287
 288         msg.msg_name = NULL;
 289         msg.msg_namelen = 0;
 290         msg.msg_control = cmsgbuf;
 291         msg.msg_controllen = sizeof(cmsgbuf);
 292
 293         iov.iov_base = data ? data : buf;
 294         iov.iov_len = data ? size : sizeof(buf);
 295         msg.msg_iov = &iov;
 296         msg.msg_iovlen = 1;
 297
 298         ret = recvmsg(fd, &msg, 0);
 299         if (ret <= 0)
 300                 goto out;
 301
 302         cmsg = CMSG_FIRSTHDR(&msg);
 303
 304         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 305             cmsg->cmsg_level == SOL_SOCKET &&
 306             cmsg->cmsg_type == SCM_CREDENTIALS) {
 307                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 308                 if (cred.uid &&
 309                     (cred.uid != getuid() || cred.gid != getgid())) {
 310                         INFO("Message denied for '%d/%d'", cred.uid, cred.gid);
 311                         errno = EACCES;
 312                         return -1;
 313                 }
 314         }
 315
 316 out:
 317         return ret;
 318 }