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
  24 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE 1
  26 #endif
  27 #include <errno.h>
  28 #include <linux/netlink.h>
  29 #include <linux/rtnetlink.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <sys/socket.h>
  34 #include <time.h>
  35 #include <unistd.h>
  36
  37 #include "config.h"
  38 #include "log.h"
  39 #include "nl.h"
  40
  41 lxc_log_define(nl, lxc);
  42
  43 extern size_t nlmsg_len(const struct nlmsg *nlmsg)
  44 {
  45         return nlmsg->nlmsghdr->nlmsg_len - NLMSG_HDRLEN;
  46 }
  47
  48 extern void *nlmsg_data(struct nlmsg *nlmsg)
  49 {
  50         char *data = ((char *)nlmsg) + NLMSG_HDRLEN;
  51         if (!nlmsg_len(nlmsg))
  52                 return NULL;
  53         return data;
  54 }
  55
  56 static int nla_put(struct nlmsg *nlmsg, int attr,
  57                    const void *data, size_t len)
  58 {
  59         struct rtattr *rta;
  60         size_t rtalen = RTA_LENGTH(len);
  61         size_t tlen = NLMSG_ALIGN(nlmsg->nlmsghdr->nlmsg_len) + RTA_ALIGN(rtalen);
  62
  63         if (tlen > nlmsg->cap)
  64                 return -ENOMEM;
  65
  66         rta = NLMSG_TAIL(nlmsg->nlmsghdr);
  67         rta->rta_type = attr;
  68         rta->rta_len = rtalen;
  69         if (data && len)
  70                 memcpy(RTA_DATA(rta), data, len);
  71         nlmsg->nlmsghdr->nlmsg_len = tlen;
  72         return 0;
  73 }
  74
  75 extern int nla_put_buffer(struct nlmsg *nlmsg, int attr,
  76                           const void *data, size_t size)
  77 {
  78         return nla_put(nlmsg, attr, data, size);
  79 }
  80
  81 extern int nla_put_string(struct nlmsg *nlmsg, int attr, const char *string)
  82 {
  83         return nla_put(nlmsg, attr, string, strlen(string) + 1);
  84 }
  85
  86 extern int nla_put_u32(struct nlmsg *nlmsg, int attr, int value)
  87 {
  88         return nla_put(nlmsg, attr, &value, sizeof(value));
  89 }
  90
  91 extern int nla_put_u16(struct nlmsg *nlmsg, int attr, unsigned short value)
  92 {
  93         return nla_put(nlmsg, attr, &value, 2);
  94 }
  95
  96 extern int nla_put_attr(struct nlmsg *nlmsg, int attr)
  97 {
  98         return nla_put(nlmsg, attr, NULL, 0);
  99 }
 100
 101 struct rtattr *nla_begin_nested(struct nlmsg *nlmsg, int attr)
 102 {
 103         struct rtattr *rtattr = NLMSG_TAIL(nlmsg->nlmsghdr);
 104
 105         if (nla_put_attr(nlmsg, attr))
 106                 return NULL;
 107
 108         return rtattr;
 109 }
 110
 111 void nla_end_nested(struct nlmsg *nlmsg, struct rtattr *attr)
 112 {
 113         attr->rta_len = (void *)NLMSG_TAIL(nlmsg->nlmsghdr) - (void *)attr;
 114 }
 115
 116 extern struct nlmsg *nlmsg_alloc(size_t size)
 117 {
 118         struct nlmsg *nlmsg;
 119         size_t len = NLMSG_HDRLEN + NLMSG_ALIGN(size);
 120
 121         nlmsg = (struct nlmsg *)malloc(sizeof(struct nlmsg));
 122         if (!nlmsg)
 123                 return NULL;
 124
 125         nlmsg->nlmsghdr = (struct nlmsghdr *)malloc(len);
 126         if (!nlmsg->nlmsghdr)
 127                 goto errout;
 128
 129         memset(nlmsg->nlmsghdr, 0, len);
 130         nlmsg->cap = len;
 131         nlmsg->nlmsghdr->nlmsg_len = NLMSG_HDRLEN;
 132
 133         return nlmsg;
 134 errout:
 135         free(nlmsg);
 136         return NULL;
 137 }
 138
 139 extern void *nlmsg_reserve(struct nlmsg *nlmsg, size_t len)
 140 {
 141         void *buf;
 142         size_t nlmsg_len = nlmsg->nlmsghdr->nlmsg_len;
 143         size_t tlen = NLMSG_ALIGN(len);
 144
 145         if (nlmsg_len + tlen > nlmsg->cap)
 146                 return NULL;
 147
 148         buf = ((char *)(nlmsg->nlmsghdr)) + nlmsg_len;
 149         nlmsg->nlmsghdr->nlmsg_len += tlen;
 150
 151         if (tlen > len)
 152                 memset(buf + len, 0, tlen - len);
 153
 154         return buf;
 155 }
 156
 157 extern struct nlmsg *nlmsg_alloc_reserve(size_t size)
 158 {
 159         struct nlmsg *nlmsg;
 160
 161         nlmsg = nlmsg_alloc(size);
 162         if (!nlmsg)
 163                 return NULL;
 164
 165         /* Just set message length to cap directly. */
 166         nlmsg->nlmsghdr->nlmsg_len = nlmsg->cap;
 167         return nlmsg;
 168 }
 169
 170 extern void nlmsg_free(struct nlmsg *nlmsg)
 171 {
 172         if (!nlmsg)
 173                 return;
 174
 175         free(nlmsg->nlmsghdr);
 176         free(nlmsg);
 177 }
 178
 179 extern int __netlink_recv(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
 180 {
 181         int ret;
 182         struct sockaddr_nl nladdr;
 183         struct iovec iov = {
 184             .iov_base = nlmsghdr,
 185             .iov_len = nlmsghdr->nlmsg_len,
 186         };
 187
 188         struct msghdr msg = {
 189             .msg_name = &nladdr,
 190             .msg_namelen = sizeof(nladdr),
 191             .msg_iov = &iov,
 192             .msg_iovlen = 1,
 193         };
 194
 195         memset(&nladdr, 0, sizeof(nladdr));
 196         nladdr.nl_family = AF_NETLINK;
 197         nladdr.nl_pid = 0;
 198         nladdr.nl_groups = 0;
 199
 200 again:
 201         ret = recvmsg(handler->fd, &msg, 0);
 202         if (ret < 0) {
 203                 if (errno == EINTR)
 204                         goto again;
 205
 206                 return -1;
 207         }
 208
 209         if (!ret)
 210                 return 0;
 211
 212         if (msg.msg_flags & MSG_TRUNC && (ret == nlmsghdr->nlmsg_len)) {
 213                 errno = EMSGSIZE;
 214                 ret = -1;
 215         }
 216
 217         return ret;
 218 }
 219
 220 extern int netlink_rcv(struct nl_handler *handler, struct nlmsg *answer)
 221 {
 222         return __netlink_recv(handler, answer->nlmsghdr);
 223 }
 224
 225 extern int __netlink_send(struct nl_handler *handler, struct nlmsghdr *nlmsghdr)
 226 {
 227         int ret;
 228         struct sockaddr_nl nladdr;
 229         struct iovec iov = {
 230             .iov_base = nlmsghdr,
 231             .iov_len = nlmsghdr->nlmsg_len,
 232         };
 233         struct msghdr msg = {
 234             .msg_name = &nladdr,
 235             .msg_namelen = sizeof(nladdr),
 236             .msg_iov = &iov,
 237             .msg_iovlen = 1,
 238         };
 239
 240         memset(&nladdr, 0, sizeof(nladdr));
 241         nladdr.nl_family = AF_NETLINK;
 242         nladdr.nl_pid = 0;
 243         nladdr.nl_groups = 0;
 244
 245         ret = sendmsg(handler->fd, &msg, MSG_NOSIGNAL);
 246         if (ret < 0)
 247                 return -1;
 248
 249         return ret;
 250 }
 251
 252 extern int netlink_send(struct nl_handler *handler, struct nlmsg *nlmsg)
 253 {
 254         return __netlink_send(handler, nlmsg->nlmsghdr);
 255 }
 256
 257 extern int __netlink_transaction(struct nl_handler *handler,
 258                                  struct nlmsghdr *request,
 259                                  struct nlmsghdr *answer)
 260 {
 261         int ret;
 262
 263         ret = __netlink_send(handler, request);
 264         if (ret < 0)
 265                 return -1;
 266
 267         ret = __netlink_recv(handler, answer);
 268         if (ret < 0)
 269                 return -1;
 270
 271         ret = 0;
 272         if (answer->nlmsg_type == NLMSG_ERROR) {
 273                 struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(answer);
 274                 errno = -err->error;
 275                 if (err->error < 0)
 276                         ret = -1;
 277         }
 278
 279         return ret;
 280 }
 281
 282 extern int netlink_transaction(struct nl_handler *handler,
 283                                struct nlmsg *request, struct nlmsg *answer)
 284 {
 285         return __netlink_transaction(handler, request->nlmsghdr,
 286                                      answer->nlmsghdr);
 287 }
 288
 289 extern int netlink_open(struct nl_handler *handler, int protocol)
 290 {
 291         socklen_t socklen;
 292         int sndbuf = 32768;
 293         int rcvbuf = 32768;
 294         int err;
 295
 296         memset(handler, 0, sizeof(*handler));
 297
 298         handler->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
 299         if (handler->fd < 0)
 300                 return -errno;
 301
 302         if (setsockopt(handler->fd, SOL_SOCKET, SO_SNDBUF,
 303                        &sndbuf, sizeof(sndbuf)) < 0)
 304                 goto err_with_errno;
 305
 306         if (setsockopt(handler->fd, SOL_SOCKET, SO_RCVBUF,
 307                        &rcvbuf,sizeof(rcvbuf)) < 0)
 308                 goto err_with_errno;
 309
 310         memset(&handler->local, 0, sizeof(handler->local));
 311         handler->local.nl_family = AF_NETLINK;
 312         handler->local.nl_groups = 0;
 313
 314         if (bind(handler->fd, (struct sockaddr*)&handler->local,
 315                  sizeof(handler->local)) < 0)
 316                 goto err_with_errno;
 317
 318         socklen = sizeof(handler->local);
 319         if (getsockname(handler->fd, (struct sockaddr*)&handler->local,
 320                         &socklen) < 0)
 321                 goto err_with_errno;
 322
 323         if (socklen != sizeof(handler->local)) {
 324                 err = -EINVAL;
 325                 goto errclose;
 326         }
 327
 328         if (handler->local.nl_family != AF_NETLINK) {
 329                 err = -EINVAL;
 330                 goto errclose;
 331         }
 332
 333         handler->seq = time(NULL);
 334
 335         return 0;
 336 err_with_errno:
 337         err = -errno;
 338 errclose:
 339         close(handler->fd);
 340         return err;
 341 }
 342
 343 extern int netlink_close(struct nl_handler *handler)
 344 {
 345         close(handler->fd);
 346         handler->fd = -1;
 347         return 0;
 348 }
 349
 350 int addattr(struct nlmsghdr *n, size_t maxlen, int type, const void *data,
 351             size_t alen)
 352 {
 353         int len = RTA_LENGTH(alen);
 354         struct rtattr *rta;
 355
 356         errno = EMSGSIZE;
 357         if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen)
 358                 return -1;
 359
 360         rta = NLMSG_TAIL(n);
 361         rta->rta_type = type;
 362         rta->rta_len = len;
 363         if (alen)
 364                 memcpy(RTA_DATA(rta), data, alen);
 365         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
 366
 367         return 0;
 368 }