src/lxc/nl.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 <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
  33 #include "nl.h"
  34
  35 #define NLMSG_TAIL(nmsg) \
  36         ((struct rtattr *) (((void *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
  37
  38 extern size_t nlmsg_len(const struct nlmsg *nlmsg)
  39 {
  40         return nlmsg->nlmsghdr->nlmsg_len - NLMSG_HDRLEN;
  41 }
  42
  43 extern void *nlmsg_data(struct nlmsg *nlmsg)
  44 {
  45         char *data = ((char *)nlmsg) + NLMSG_HDRLEN;
  46         if (!nlmsg_len(nlmsg))
  47                 return NULL;
  48         return data;
  49 }
  50
  51 static int nla_put(struct nlmsg *nlmsg, int attr,
  52                    const void *data, size_t len)
  53 {
  54         struct rtattr *rta;
  55         size_t rtalen = RTA_LENGTH(len);
  56         size_t tlen = NLMSG_ALIGN(nlmsg->nlmsghdr->nlmsg_len) + RTA_ALIGN(rtalen);
  57
  58         if (tlen > nlmsg->cap)
  59                 return -ENOMEM;
  60
  61         rta = NLMSG_TAIL(nlmsg->nlmsghdr);
  62         rta->rta_type = attr;
  63         rta->rta_len = rtalen;
  64         if (data && len)
  65                 memcpy(RTA_DATA(rta), data, len);
  66         nlmsg->nlmsghdr->nlmsg_len = tlen;
  67         return 0;
  68 }
  69
  70 extern int nla_put_buffer(struct nlmsg *nlmsg, int attr,
  71                           const void *data, size_t size)
  72 {
  73         return nla_put(nlmsg, attr, data, size);
  74 }
  75
  76 extern int nla_put_string(struct nlmsg *nlmsg, int attr, const char *string)
  77 {
  78         return nla_put(nlmsg, attr, string, strlen(string) + 1);
  79 }
  80
  81 extern int nla_put_u32(struct nlmsg *nlmsg, int attr, int value)
  82 {
  83         return nla_put(nlmsg, attr, &value, sizeof(value));
  84 }
  85
  86 extern int nla_put_u16(struct nlmsg *nlmsg, int attr, unsigned short value)
  87 {
  88         return nla_put(nlmsg, attr, &value, 2);
  89 }
  90
  91 extern int nla_put_attr(struct nlmsg *nlmsg, int attr)
  92 {
  93         return nla_put(nlmsg, attr, NULL, 0);
  94 }
  95
  96 struct rtattr *nla_begin_nested(struct nlmsg *nlmsg, int attr)
  97 {
  98         struct rtattr *rtattr = NLMSG_TAIL(nlmsg->nlmsghdr);
  99
 100         if (nla_put_attr(nlmsg, attr))
 101                 return NULL;
 102
 103         return rtattr;
 104 }
 105
 106 void nla_end_nested(struct nlmsg *nlmsg, struct rtattr *attr)
 107 {
 108         attr->rta_len = (void *)NLMSG_TAIL(nlmsg->nlmsghdr) - (void *)attr;
 109 }
 110
 111 extern struct nlmsg *nlmsg_alloc(size_t size)
 112 {
 113         struct nlmsg *nlmsg;
 114         size_t len = NLMSG_HDRLEN + NLMSG_ALIGN(size);
 115
 116         nlmsg = (struct nlmsg *)malloc(sizeof(struct nlmsg));
 117         if (!nlmsg)
 118                 return NULL;
 119
 120         nlmsg->nlmsghdr = (struct nlmsghdr *)malloc(len);
 121         if (!nlmsg->nlmsghdr)
 122                 goto errout;
 123
 124         memset(nlmsg->nlmsghdr, 0, len);
 125         nlmsg->cap = len;
 126         nlmsg->nlmsghdr->nlmsg_len = NLMSG_HDRLEN;
 127
 128         return nlmsg;
 129 errout:
 130         free(nlmsg);
 131         return NULL;
 132 }
 133
 134 extern void *nlmsg_reserve(struct nlmsg *nlmsg, size_t len)
 135 {
 136         void *buf;
 137         size_t nlmsg_len = nlmsg->nlmsghdr->nlmsg_len;
 138         size_t tlen = NLMSG_ALIGN(len);
 139
 140         if (nlmsg_len + tlen > nlmsg->cap)
 141                 return NULL;
 142
 143         buf = ((char *)(nlmsg->nlmsghdr)) + nlmsg_len;
 144         nlmsg->nlmsghdr->nlmsg_len += tlen;
 145
 146         if (tlen > len)
 147                 memset(buf + len, 0, tlen - len);
 148
 149         return buf;
 150 }
 151
 152 extern struct nlmsg *nlmsg_alloc_reserve(size_t size)
 153 {
 154         struct nlmsg *nlmsg;
 155
 156         nlmsg = nlmsg_alloc(size);
 157         if (!nlmsg)
 158                 return NULL;
 159
 160         /* Just set message length to cap directly. */
 161         nlmsg->nlmsghdr->nlmsg_len = nlmsg->cap;
 162         return nlmsg;
 163 }
 164
 165 extern void nlmsg_free(struct nlmsg *nlmsg)
 166 {
 167         if (!nlmsg)
 168                 return;
 169
 170         free(nlmsg->nlmsghdr);
 171         free(nlmsg);
 172 }
 173
 174 extern int __netlink_recv(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
 175 {
 176         int ret;
 177         struct sockaddr_nl nladdr;
 178         struct iovec iov = {
 179             .iov_base = nlmsghdr,
 180             .iov_len = nlmsghdr->nlmsg_len,
 181         };
 182
 183         struct msghdr msg = {
 184             .msg_name = &nladdr,
 185             .msg_namelen = sizeof(nladdr),
 186             .msg_iov = &iov,
 187             .msg_iovlen = 1,
 188         };
 189
 190         memset(&nladdr, 0, sizeof(nladdr));
 191         nladdr.nl_family = AF_NETLINK;
 192         nladdr.nl_pid = 0;
 193         nladdr.nl_groups = 0;
 194
 195 again:
 196         ret = recvmsg(handler->fd, &msg, 0);
 197         if (ret < 0) {
 198                 if (errno == EINTR)
 199                         goto again;
 200
 201                 return -1;
 202         }
 203
 204         if (!ret)
 205                 return 0;
 206
 207         if (msg.msg_flags & MSG_TRUNC && (ret == nlmsghdr->nlmsg_len))
 208                 return -EMSGSIZE;
 209
 210         return ret;
 211 }
 212
 213 extern int netlink_rcv(struct nl_handler *handler, struct nlmsg *answer)
 214 {
 215         return __netlink_recv(handler, answer->nlmsghdr);
 216 }
 217
 218 extern int __netlink_send(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
 219 {
 220         int ret;
 221         struct sockaddr_nl nladdr;
 222         struct iovec iov = {
 223             .iov_base = nlmsghdr,
 224             .iov_len = nlmsghdr->nlmsg_len,
 225         };
 226         struct msghdr msg = {
 227             .msg_name = &nladdr,
 228             .msg_namelen = sizeof(nladdr),
 229             .msg_iov = &iov,
 230             .msg_iovlen = 1,
 231         };
 232
 233         memset(&nladdr, 0, sizeof(nladdr));
 234         nladdr.nl_family = AF_NETLINK;
 235         nladdr.nl_pid = 0;
 236         nladdr.nl_groups = 0;
 237
 238         ret = sendmsg(handler->fd, &msg, MSG_NOSIGNAL);
 239         if (ret < 0)
 240                 return -1;
 241
 242         return ret;
 243 }
 244
 245 extern int netlink_send(struct nl_handler *handler, struct nlmsg *nlmsg)
 246 {
 247         return __netlink_send(handler, nlmsg->nlmsghdr);
 248 }
 249
 250 extern int __netlink_transaction(struct nl_handler *handler,
 251                                  struct nlmsghdr *request,
 252                                  struct nlmsghdr *answer)
 253 {
 254         int ret;
 255
 256         ret = __netlink_send(handler, request);
 257         if (ret < 0)
 258                 return ret;
 259
 260         ret = __netlink_recv(handler, answer);
 261         if (ret < 0)
 262                 return ret;
 263
 264         if (answer->nlmsg_type == NLMSG_ERROR) {
 265                 struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(answer);
 266                 return err->error;
 267         }
 268
 269         return 0;
 270 }
 271
 272 extern int netlink_transaction(struct nl_handler *handler,
 273                                struct nlmsg *request, struct nlmsg *answer)
 274 {
 275         return __netlink_transaction(handler, request->nlmsghdr,
 276                                      answer->nlmsghdr);
 277 }
 278
 279 extern int netlink_open(struct nl_handler *handler, int protocol)
 280 {
 281         socklen_t socklen;
 282         int sndbuf = 32768;
 283         int rcvbuf = 32768;
 284         int err;
 285
 286         memset(handler, 0, sizeof(*handler));
 287
 288         handler->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
 289         if (handler->fd < 0)
 290                 return -errno;
 291
 292         if (setsockopt(handler->fd, SOL_SOCKET, SO_SNDBUF,
 293                        &sndbuf, sizeof(sndbuf)) < 0)
 294                 goto err_with_errno;
 295
 296         if (setsockopt(handler->fd, SOL_SOCKET, SO_RCVBUF,
 297                        &rcvbuf,sizeof(rcvbuf)) < 0)
 298                 goto err_with_errno;
 299
 300         memset(&handler->local, 0, sizeof(handler->local));
 301         handler->local.nl_family = AF_NETLINK;
 302         handler->local.nl_groups = 0;
 303
 304         if (bind(handler->fd, (struct sockaddr*)&handler->local,
 305                  sizeof(handler->local)) < 0)
 306                 goto err_with_errno;
 307
 308         socklen = sizeof(handler->local);
 309         if (getsockname(handler->fd, (struct sockaddr*)&handler->local,
 310                         &socklen) < 0)
 311                 goto err_with_errno;
 312
 313         if (socklen != sizeof(handler->local)) {
 314                 err = -EINVAL;
 315                 goto errclose;
 316         }
 317
 318         if (handler->local.nl_family != AF_NETLINK) {
 319                 err = -EINVAL;
 320                 goto errclose;
 321         }
 322
 323         handler->seq = time(NULL);
 324
 325         return 0;
 326 err_with_errno:
 327         err = -errno;
 328 errclose:
 329         close(handler->fd);
 330         return err;
 331 }
 332
 333 extern int netlink_close(struct nl_handler *handler)
 334 {
 335         close(handler->fd);
 336         handler->fd = -1;
 337         return 0;
 338 }
 339