fs/afs/use-rtnetlink.c

   1 /* RTNETLINK client
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11 #include <linux/netlink.h>
  12 #include <linux/rtnetlink.h>
  13 #include <linux/if_addr.h>
  14 #include <linux/if_arp.h>
  15 #include <linux/inetdevice.h>
  16 #include <net/netlink.h>
  17 #include "internal.h"
  18
  19 struct afs_rtm_desc {
  20         struct socket           *nlsock;
  21         struct afs_interface    *bufs;
  22         u8                      *mac;
  23         size_t                  nbufs;
  24         size_t                  maxbufs;
  25         void                    *data;
  26         ssize_t                 datalen;
  27         size_t                  datamax;
  28         int                     msg_seq;
  29         unsigned                mac_index;
  30         bool                    wantloopback;
  31         int (*parse)(struct afs_rtm_desc *, struct nlmsghdr *);
  32 };
  33
  34 /*
  35  * parse an RTM_GETADDR response
  36  */
  37 static int afs_rtm_getaddr_parse(struct afs_rtm_desc *desc,
  38                                  struct nlmsghdr *nlhdr)
  39 {
  40         struct afs_interface *this;
  41         struct ifaddrmsg *ifa;
  42         struct rtattr *rtattr;
  43         const char *name;
  44         size_t len;
  45
  46         ifa = (struct ifaddrmsg *) NLMSG_DATA(nlhdr);
  47
  48         _enter("{ix=%d,af=%d}", ifa->ifa_index, ifa->ifa_family);
  49
  50         if (ifa->ifa_family != AF_INET) {
  51                 _leave(" = 0 [family %d]", ifa->ifa_family);
  52                 return 0;
  53         }
  54         if (desc->nbufs >= desc->maxbufs) {
  55                 _leave(" = 0 [max %zu/%zu]", desc->nbufs, desc->maxbufs);
  56                 return 0;
  57         }
  58
  59         this = &desc->bufs[desc->nbufs];
  60
  61         this->index = ifa->ifa_index;
  62         this->netmask.s_addr = inet_make_mask(ifa->ifa_prefixlen);
  63         this->mtu = 0;
  64
  65         rtattr = NLMSG_DATA(nlhdr) + NLMSG_ALIGN(sizeof(struct ifaddrmsg));
  66         len = NLMSG_PAYLOAD(nlhdr, sizeof(struct ifaddrmsg));
  67
  68         name = "unknown";
  69         for (; RTA_OK(rtattr, len); rtattr = RTA_NEXT(rtattr, len)) {
  70                 switch (rtattr->rta_type) {
  71                 case IFA_ADDRESS:
  72                         memcpy(&this->address, RTA_DATA(rtattr), 4);
  73                         break;
  74                 case IFA_LABEL:
  75                         name = RTA_DATA(rtattr);
  76                         break;
  77                 }
  78         }
  79
  80         _debug("%s: "NIPQUAD_FMT"/"NIPQUAD_FMT,
  81                name, NIPQUAD(this->address), NIPQUAD(this->netmask));
  82
  83         desc->nbufs++;
  84         _leave(" = 0");
  85         return 0;
  86 }
  87
  88 /*
  89  * parse an RTM_GETLINK response for MTUs
  90  */
  91 static int afs_rtm_getlink_if_parse(struct afs_rtm_desc *desc,
  92                                     struct nlmsghdr *nlhdr)
  93 {
  94         struct afs_interface *this;
  95         struct ifinfomsg *ifi;
  96         struct rtattr *rtattr;
  97         const char *name;
  98         size_t len, loop;
  99
 100         ifi = (struct ifinfomsg *) NLMSG_DATA(nlhdr);
 101
 102         _enter("{ix=%d}", ifi->ifi_index);
 103
 104         for (loop = 0; loop < desc->nbufs; loop++) {
 105                 this = &desc->bufs[loop];
 106                 if (this->index == ifi->ifi_index)
 107                         goto found;
 108         }
 109
 110         _leave(" = 0 [no match]");
 111         return 0;
 112
 113 found:
 114         if (ifi->ifi_type == ARPHRD_LOOPBACK && !desc->wantloopback) {
 115                 _leave(" = 0 [loopback]");
 116                 return 0;
 117         }
 118
 119         rtattr = NLMSG_DATA(nlhdr) + NLMSG_ALIGN(sizeof(struct ifinfomsg));
 120         len = NLMSG_PAYLOAD(nlhdr, sizeof(struct ifinfomsg));
 121
 122         name = "unknown";
 123         for (; RTA_OK(rtattr, len); rtattr = RTA_NEXT(rtattr, len)) {
 124                 switch (rtattr->rta_type) {
 125                 case IFLA_MTU:
 126                         memcpy(&this->mtu, RTA_DATA(rtattr), 4);
 127                         break;
 128                 case IFLA_IFNAME:
 129                         name = RTA_DATA(rtattr);
 130                         break;
 131                 }
 132         }
 133
 134         _debug("%s: "NIPQUAD_FMT"/"NIPQUAD_FMT" mtu %u",
 135                name, NIPQUAD(this->address), NIPQUAD(this->netmask),
 136                this->mtu);
 137
 138         _leave(" = 0");
 139         return 0;
 140 }
 141
 142 /*
 143  * parse an RTM_GETLINK response for the MAC address belonging to the lowest
 144  * non-internal interface
 145  */
 146 static int afs_rtm_getlink_mac_parse(struct afs_rtm_desc *desc,
 147                                      struct nlmsghdr *nlhdr)
 148 {
 149         struct ifinfomsg *ifi;
 150         struct rtattr *rtattr;
 151         const char *name;
 152         size_t remain, len;
 153         bool set;
 154
 155         ifi = (struct ifinfomsg *) NLMSG_DATA(nlhdr);
 156
 157         _enter("{ix=%d}", ifi->ifi_index);
 158
 159         if (ifi->ifi_index >= desc->mac_index) {
 160                 _leave(" = 0 [high]");
 161                 return 0;
 162         }
 163         if (ifi->ifi_type == ARPHRD_LOOPBACK) {
 164                 _leave(" = 0 [loopback]");
 165                 return 0;
 166         }
 167
 168         rtattr = NLMSG_DATA(nlhdr) + NLMSG_ALIGN(sizeof(struct ifinfomsg));
 169         remain = NLMSG_PAYLOAD(nlhdr, sizeof(struct ifinfomsg));
 170
 171         name = "unknown";
 172         set = false;
 173         for (; RTA_OK(rtattr, remain); rtattr = RTA_NEXT(rtattr, remain)) {
 174                 switch (rtattr->rta_type) {
 175                 case IFLA_ADDRESS:
 176                         len = RTA_PAYLOAD(rtattr);
 177                         memcpy(desc->mac, RTA_DATA(rtattr),
 178                                min_t(size_t, len, 6));
 179                         desc->mac_index = ifi->ifi_index;
 180                         set = true;
 181                         break;
 182                 case IFLA_IFNAME:
 183                         name = RTA_DATA(rtattr);
 184                         break;
 185                 }
 186         }
 187
 188         if (set)
 189                 _debug("%s: %02x:%02x:%02x:%02x:%02x:%02x",
 190                        name,
 191                        desc->mac[0], desc->mac[1], desc->mac[2],
 192                        desc->mac[3], desc->mac[4], desc->mac[5]);
 193
 194         _leave(" = 0");
 195         return 0;
 196 }
 197
 198 /*
 199  * read the rtnetlink response and pass to parsing routine
 200  */
 201 static int afs_read_rtm(struct afs_rtm_desc *desc)
 202 {
 203         struct nlmsghdr *nlhdr, tmphdr;
 204         struct msghdr msg;
 205         struct kvec iov[1];
 206         void *data;
 207         bool last = false;
 208         int len, ret, remain;
 209
 210         _enter("");
 211
 212         do {
 213                 /* first of all peek to see how big the packet is */
 214                 memset(&msg, 0, sizeof(msg));
 215                 iov[0].iov_base = &tmphdr;
 216                 iov[0].iov_len = sizeof(tmphdr);
 217                 len = kernel_recvmsg(desc->nlsock, &msg, iov, 1,
 218                                      sizeof(tmphdr), MSG_PEEK | MSG_TRUNC);
 219                 if (len < 0) {
 220                         _leave(" = %d [peek]", len);
 221                         return len;
 222                 }
 223                 if (len == 0)
 224                         continue;
 225                 if (len < sizeof(tmphdr) || len < NLMSG_PAYLOAD(&tmphdr, 0)) {
 226                         _leave(" = -EMSGSIZE");
 227                         return -EMSGSIZE;
 228                 }
 229
 230                 if (desc->datamax < len) {
 231                         kfree(desc->data);
 232                         desc->data = NULL;
 233                         data = kmalloc(len, GFP_KERNEL);
 234                         if (!data)
 235                                 return -ENOMEM;
 236                         desc->data = data;
 237                 }
 238                 desc->datamax = len;
 239
 240                 /* read all the data from this packet */
 241                 iov[0].iov_base = desc->data;
 242                 iov[0].iov_len = desc->datamax;
 243                 desc->datalen = kernel_recvmsg(desc->nlsock, &msg, iov, 1,
 244                                                desc->datamax, 0);
 245                 if (desc->datalen < 0) {
 246                         _leave(" = %zd [recv]", desc->datalen);
 247                         return desc->datalen;
 248                 }
 249
 250                 nlhdr = desc->data;
 251
 252                 /* check if the header is valid */
 253                 if (!NLMSG_OK(nlhdr, desc->datalen) ||
 254                     nlhdr->nlmsg_type == NLMSG_ERROR) {
 255                         _leave(" = -EIO");
 256                         return -EIO;
 257                 }
 258
 259                 /* see if this is the last message */
 260                 if (nlhdr->nlmsg_type == NLMSG_DONE ||
 261                     !(nlhdr->nlmsg_flags & NLM_F_MULTI))
 262                         last = true;
 263
 264                 /* parse the bits we got this time */
 265                 nlmsg_for_each_msg(nlhdr, desc->data, desc->datalen, remain) {
 266                         ret = desc->parse(desc, nlhdr);
 267                         if (ret < 0) {
 268                                 _leave(" = %d [parse]", ret);
 269                                 return ret;
 270                         }
 271                 }
 272
 273         } while (!last);
 274
 275         _leave(" = 0");
 276         return 0;
 277 }
 278
 279 /*
 280  * list the interface bound addresses to get the address and netmask
 281  */
 282 static int afs_rtm_getaddr(struct afs_rtm_desc *desc)
 283 {
 284         struct msghdr msg;
 285         struct kvec iov[1];
 286         int ret;
 287
 288         struct {
 289                 struct nlmsghdr nl_msg __attribute__((aligned(NLMSG_ALIGNTO)));
 290                 struct ifaddrmsg addr_msg __attribute__((aligned(NLMSG_ALIGNTO)));
 291         } request;
 292
 293         _enter("");
 294
 295         memset(&request, 0, sizeof(request));
 296
 297         request.nl_msg.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
 298         request.nl_msg.nlmsg_type = RTM_GETADDR;
 299         request.nl_msg.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
 300         request.nl_msg.nlmsg_seq = desc->msg_seq++;
 301         request.nl_msg.nlmsg_pid = 0;
 302
 303         memset(&msg, 0, sizeof(msg));
 304         iov[0].iov_base = &request;
 305         iov[0].iov_len = sizeof(request);
 306
 307         ret = kernel_sendmsg(desc->nlsock, &msg, iov, 1, iov[0].iov_len);
 308         _leave(" = %d", ret);
 309         return ret;
 310 }
 311
 312 /*
 313  * list the interface link statuses to get the MTUs
 314  */
 315 static int afs_rtm_getlink(struct afs_rtm_desc *desc)
 316 {
 317         struct msghdr msg;
 318         struct kvec iov[1];
 319         int ret;
 320
 321         struct {
 322                 struct nlmsghdr nl_msg __attribute__((aligned(NLMSG_ALIGNTO)));
 323                 struct ifinfomsg link_msg __attribute__((aligned(NLMSG_ALIGNTO)));
 324         } request;
 325
 326         _enter("");
 327
 328         memset(&request, 0, sizeof(request));
 329
 330         request.nl_msg.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
 331         request.nl_msg.nlmsg_type = RTM_GETLINK;
 332         request.nl_msg.nlmsg_flags = NLM_F_REQUEST | NLM_F_ROOT;
 333         request.nl_msg.nlmsg_seq = desc->msg_seq++;
 334         request.nl_msg.nlmsg_pid = 0;
 335
 336         memset(&msg, 0, sizeof(msg));
 337         iov[0].iov_base = &request;
 338         iov[0].iov_len = sizeof(request);
 339
 340         ret = kernel_sendmsg(desc->nlsock, &msg, iov, 1, iov[0].iov_len);
 341         _leave(" = %d", ret);
 342         return ret;
 343 }
 344
 345 /*
 346  * cull any interface records for which there isn't an MTU value
 347  */
 348 static void afs_cull_interfaces(struct afs_rtm_desc *desc)
 349 {
 350         struct afs_interface *bufs = desc->bufs;
 351         size_t nbufs = desc->nbufs;
 352         int loop, point = 0;
 353
 354         _enter("{%zu}", nbufs);
 355
 356         for (loop = 0; loop < nbufs; loop++) {
 357                 if (desc->bufs[loop].mtu != 0) {
 358                         if (loop != point) {
 359                                 ASSERTCMP(loop, >, point);
 360                                 bufs[point] = bufs[loop];
 361                         }
 362                         point++;
 363                 }
 364         }
 365
 366         desc->nbufs = point;
 367         _leave(" [%zu/%zu]", desc->nbufs, nbufs);
 368 }
 369
 370 /*
 371  * get a list of this system's interface IPv4 addresses, netmasks and MTUs
 372  * - returns the number of interface records in the buffer
 373  */
 374 int afs_get_ipv4_interfaces(struct afs_interface *bufs, size_t maxbufs,
 375                             bool wantloopback)
 376 {
 377         struct afs_rtm_desc desc;
 378         int ret, loop;
 379
 380         _enter("");
 381
 382         memset(&desc, 0, sizeof(desc));
 383         desc.bufs = bufs;
 384         desc.maxbufs = maxbufs;
 385         desc.wantloopback = wantloopback;
 386
 387         ret = sock_create_kern(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE,
 388                                &desc.nlsock);
 389         if (ret < 0) {
 390                 _leave(" = %d [sock]", ret);
 391                 return ret;
 392         }
 393
 394         /* issue RTM_GETADDR */
 395         desc.parse = afs_rtm_getaddr_parse;
 396         ret = afs_rtm_getaddr(&desc);
 397         if (ret < 0)
 398                 goto error;
 399         ret = afs_read_rtm(&desc);
 400         if (ret < 0)
 401                 goto error;
 402
 403         /* issue RTM_GETLINK */
 404         desc.parse = afs_rtm_getlink_if_parse;
 405         ret = afs_rtm_getlink(&desc);
 406         if (ret < 0)
 407                 goto error;
 408         ret = afs_read_rtm(&desc);
 409         if (ret < 0)
 410                 goto error;
 411
 412         afs_cull_interfaces(&desc);
 413         ret = desc.nbufs;
 414
 415         for (loop = 0; loop < ret; loop++)
 416                 _debug("[%d] "NIPQUAD_FMT"/"NIPQUAD_FMT" mtu %u",
 417                        bufs[loop].index,
 418                        NIPQUAD(bufs[loop].address),
 419                        NIPQUAD(bufs[loop].netmask),
 420                        bufs[loop].mtu);
 421
 422 error:
 423         kfree(desc.data);
 424         sock_release(desc.nlsock);
 425         _leave(" = %d", ret);
 426         return ret;
 427 }
 428
 429 /*
 430  * get a MAC address from a random ethernet interface that has a real one
 431  * - the buffer should be 6 bytes in size
 432  */
 433 int afs_get_MAC_address(u8 mac[6])
 434 {
 435         struct afs_rtm_desc desc;
 436         int ret;
 437
 438         _enter("");
 439
 440         memset(&desc, 0, sizeof(desc));
 441         desc.mac = mac;
 442         desc.mac_index = UINT_MAX;
 443
 444         ret = sock_create_kern(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE,
 445                                &desc.nlsock);
 446         if (ret < 0) {
 447                 _leave(" = %d [sock]", ret);
 448                 return ret;
 449         }
 450
 451         /* issue RTM_GETLINK */
 452         desc.parse = afs_rtm_getlink_mac_parse;
 453         ret = afs_rtm_getlink(&desc);
 454         if (ret < 0)
 455                 goto error;
 456         ret = afs_read_rtm(&desc);
 457         if (ret < 0)
 458                 goto error;
 459
 460         if (desc.mac_index < UINT_MAX) {
 461                 /* got a MAC address */
 462                 _debug("[%d] %02x:%02x:%02x:%02x:%02x:%02x",
 463                        desc.mac_index,
 464                        mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
 465         } else {
 466                 ret = -ENONET;
 467         }
 468
 469 error:
 470         sock_release(desc.nlsock);
 471         _leave(" = %d", ret);
 472         return ret;
 473 }