src/lxc/nl.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <dlezcano at fr.ibm.com>
   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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  */
  23 #include <sys/socket.h>
  24 #include <string.h>
  25 #include <stdio.h>
  26 #include <time.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29 #include <stdlib.h>
  30 #include <linux/netlink.h>
  31 #include <linux/rtnetlink.h>
  32 #include <nl.h>
  33
  34 #define NLMSG_TAIL(nmsg) \
  35         ((struct rtattr *) (((void *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
  36
  37 extern size_t nlmsg_len(const struct nlmsg *nlmsg)
  38 {
  39         return nlmsg->nlmsghdr.nlmsg_len - NLMSG_HDRLEN;
  40 }
  41
  42 extern void *nlmsg_data(struct nlmsg *nlmsg)
  43 {
  44         char *data = ((char *)nlmsg) + NLMSG_ALIGN(sizeof(struct nlmsghdr));
  45         if (!nlmsg_len(nlmsg))
  46                 return NULL;
  47         return data;
  48 }
  49
  50 static int nla_put(struct nlmsg *nlmsg, int attr,
  51                    const void *data, size_t len)
  52 {
  53         struct rtattr *rta;
  54         size_t rtalen = RTA_LENGTH(len);
  55
  56         rta = NLMSG_TAIL(&nlmsg->nlmsghdr);
  57         rta->rta_type = attr;
  58         rta->rta_len = rtalen;
  59         memcpy(RTA_DATA(rta), data, len);
  60         nlmsg->nlmsghdr.nlmsg_len =
  61                 NLMSG_ALIGN(nlmsg->nlmsghdr.nlmsg_len) + RTA_ALIGN(rtalen);
  62         return 0;
  63 }
  64
  65 extern int nla_put_buffer(struct nlmsg *nlmsg, int attr,
  66                           const void *data, size_t size)
  67 {
  68         return nla_put(nlmsg, attr, data, size);
  69 }
  70
  71 extern int nla_put_string(struct nlmsg *nlmsg, int attr, const char *string)
  72 {
  73         return nla_put(nlmsg, attr, string, strlen(string) + 1);
  74 }
  75
  76 extern int nla_put_u32(struct nlmsg *nlmsg, int attr, int value)
  77 {
  78         return nla_put(nlmsg, attr, &value, sizeof(value));
  79 }
  80
  81 extern int nla_put_attr(struct nlmsg *nlmsg, int attr)
  82 {
  83         return nla_put(nlmsg, attr, NULL, 0);
  84 }
  85
  86 struct rtattr *nla_begin_nested(struct nlmsg *nlmsg, int attr)
  87 {
  88         struct rtattr *rtattr = NLMSG_TAIL(&nlmsg->nlmsghdr);
  89
  90         if (nla_put_attr(nlmsg, attr))
  91                 return NULL;
  92
  93         return rtattr;
  94 }
  95
  96 void nla_end_nested(struct nlmsg *nlmsg, struct rtattr *attr)
  97 {
  98         attr->rta_len = (void *)NLMSG_TAIL(&nlmsg->nlmsghdr) - (void *)attr;
  99 }
 100
 101 extern struct nlmsg *nlmsg_alloc(size_t size)
 102 {
 103         struct nlmsg *nlmsg;
 104         size_t len = NLMSG_ALIGN(size) + NLMSG_ALIGN(sizeof(struct nlmsghdr *));
 105
 106         nlmsg = (struct nlmsg *)malloc(len);
 107         if (!nlmsg)
 108                 return NULL;
 109
 110         memset(nlmsg, 0, len);
 111         nlmsg->nlmsghdr.nlmsg_len = NLMSG_ALIGN(size);
 112
 113         return nlmsg;
 114 }
 115
 116 extern void nlmsg_free(struct nlmsg *nlmsg)
 117 {
 118         free(nlmsg);
 119 }
 120
 121 extern int netlink_rcv(struct nl_handler *handler, struct nlmsg *answer)
 122 {
 123         int ret;
 124         struct sockaddr_nl nladdr;
 125         struct iovec iov = {
 126                 .iov_base = answer,
 127                 .iov_len = answer->nlmsghdr.nlmsg_len,
 128         };
 129
 130         struct msghdr msg = {
 131                 .msg_name = &nladdr,
 132                 .msg_namelen = sizeof(nladdr),
 133                 .msg_iov = &iov,
 134                 .msg_iovlen = 1,
 135         };
 136
 137         memset(&nladdr, 0, sizeof(nladdr));
 138         nladdr.nl_family = AF_NETLINK;
 139         nladdr.nl_pid = 0;
 140         nladdr.nl_groups = 0;
 141
 142 again:
 143         ret = recvmsg(handler->fd, &msg, 0);
 144         if (ret < 0) {
 145                 if (errno == EINTR)
 146                         goto again;
 147                 return -errno;
 148         }
 149
 150         if (!ret)
 151                 return 0;
 152
 153         if (msg.msg_flags & MSG_TRUNC)
 154                 return -EMSGSIZE;
 155
 156         return ret;
 157 }
 158
 159 extern int netlink_send(struct nl_handler *handler, struct nlmsg *nlmsg)
 160 {
 161         struct sockaddr_nl nladdr;
 162         struct iovec iov = {
 163                 .iov_base = (void*)nlmsg,
 164                 .iov_len = nlmsg->nlmsghdr.nlmsg_len,
 165         };
 166         struct msghdr msg = {
 167                 .msg_name = &nladdr,
 168                 .msg_namelen = sizeof(nladdr),
 169                 .msg_iov = &iov,
 170                 .msg_iovlen = 1,
 171         };
 172         int ret;
 173
 174         memset(&nladdr, 0, sizeof(nladdr));
 175         nladdr.nl_family = AF_NETLINK;
 176         nladdr.nl_pid = 0;
 177         nladdr.nl_groups = 0;
 178
 179         ret = sendmsg(handler->fd, &msg, 0);
 180         if (ret < 0) {
 181                 return -errno;
 182         }
 183
 184         return ret;
 185 }
 186
 187 extern int netlink_transaction(struct nl_handler *handler,
 188                                struct nlmsg *request, struct nlmsg *answer)
 189 {
 190
 191         int ret;
 192
 193         ret = netlink_send(handler, request);
 194         if (ret < 0)
 195                 return ret;
 196
 197         ret = netlink_rcv(handler, answer);
 198         if (ret < 0)
 199                 return ret;
 200
 201         if (answer->nlmsghdr.nlmsg_type == NLMSG_ERROR) {
 202                 struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(answer);
 203                 errno = -err->error;
 204                 return -errno;
 205         }
 206
 207         return 0;
 208 }
 209
 210 extern int netlink_open(struct nl_handler *handler, int protocol)
 211 {
 212         socklen_t socklen;
 213         int sndbuf = 32768;
 214         int rcvbuf = 32768;
 215
 216         memset(handler, 0, sizeof(*handler));
 217
 218         handler->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
 219         if (handler->fd < 0)
 220                 return -errno;
 221
 222         if (setsockopt(handler->fd, SOL_SOCKET, SO_SNDBUF,
 223                        &sndbuf, sizeof(sndbuf)) < 0)
 224                 return -errno;
 225
 226         if (setsockopt(handler->fd, SOL_SOCKET, SO_RCVBUF,
 227                        &rcvbuf,sizeof(rcvbuf)) < 0)
 228                 return -errno;
 229
 230         memset(&handler->local, 0, sizeof(handler->local));
 231         handler->local.nl_family = AF_NETLINK;
 232         handler->local.nl_groups = 0;
 233
 234         if (bind(handler->fd, (struct sockaddr*)&handler->local,
 235                  sizeof(handler->local)) < 0)
 236                 return -errno;
 237
 238         socklen = sizeof(handler->local);
 239         if (getsockname(handler->fd, (struct sockaddr*)&handler->local,
 240                         &socklen) < 0)
 241                 return -errno;
 242
 243         if (socklen != sizeof(handler->local))
 244                 return -EINVAL;
 245
 246         if (handler->local.nl_family != AF_NETLINK)
 247                 return -EINVAL;
 248
 249         handler->seq = time(NULL);
 250
 251         return 0;
 252 }
 253
 254 extern int netlink_close(struct nl_handler *handler)
 255 {
 256         close(handler->fd);
 257         handler->fd = -1;
 258         return 0;
 259 }
 260