tools/testing/selftests/bpf/netlink_helpers.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Taken & modified from iproute2's libnetlink.c
   3  * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   4  */
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8 #include <errno.h>
   9 #include <time.h>
  10 #include <sys/socket.h>
  11
  12 #include "netlink_helpers.h"
  13
  14 static int rcvbuf = 1024 * 1024;
  15
  16 void rtnl_close(struct rtnl_handle *rth)
  17 {
  18         if (rth->fd >= 0) {
  19                 close(rth->fd);
  20                 rth->fd = -1;
  21         }
  22 }
  23
  24 int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
  25                       int protocol)
  26 {
  27         socklen_t addr_len;
  28         int sndbuf = 32768;
  29         int one = 1;
  30
  31         memset(rth, 0, sizeof(*rth));
  32         rth->proto = protocol;
  33         rth->fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, protocol);
  34         if (rth->fd < 0) {
  35                 perror("Cannot open netlink socket");
  36                 return -1;
  37         }
  38         if (setsockopt(rth->fd, SOL_SOCKET, SO_SNDBUF,
  39                        &sndbuf, sizeof(sndbuf)) < 0) {
  40                 perror("SO_SNDBUF");
  41                 goto err;
  42         }
  43         if (setsockopt(rth->fd, SOL_SOCKET, SO_RCVBUF,
  44                        &rcvbuf, sizeof(rcvbuf)) < 0) {
  45                 perror("SO_RCVBUF");
  46                 goto err;
  47         }
  48
  49         /* Older kernels may no support extended ACK reporting */
  50         setsockopt(rth->fd, SOL_NETLINK, NETLINK_EXT_ACK,
  51                    &one, sizeof(one));
  52
  53         memset(&rth->local, 0, sizeof(rth->local));
  54         rth->local.nl_family = AF_NETLINK;
  55         rth->local.nl_groups = subscriptions;
  56
  57         if (bind(rth->fd, (struct sockaddr *)&rth->local,
  58                  sizeof(rth->local)) < 0) {
  59                 perror("Cannot bind netlink socket");
  60                 goto err;
  61         }
  62         addr_len = sizeof(rth->local);
  63         if (getsockname(rth->fd, (struct sockaddr *)&rth->local,
  64                         &addr_len) < 0) {
  65                 perror("Cannot getsockname");
  66                 goto err;
  67         }
  68         if (addr_len != sizeof(rth->local)) {
  69                 fprintf(stderr, "Wrong address length %d\n", addr_len);
  70                 goto err;
  71         }
  72         if (rth->local.nl_family != AF_NETLINK) {
  73                 fprintf(stderr, "Wrong address family %d\n",
  74                         rth->local.nl_family);
  75                 goto err;
  76         }
  77         rth->seq = time(NULL);
  78         return 0;
  79 err:
  80         rtnl_close(rth);
  81         return -1;
  82 }
  83
  84 int rtnl_open(struct rtnl_handle *rth, unsigned int subscriptions)
  85 {
  86         return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
  87 }
  88
  89 static int __rtnl_recvmsg(int fd, struct msghdr *msg, int flags)
  90 {
  91         int len;
  92
  93         do {
  94                 len = recvmsg(fd, msg, flags);
  95         } while (len < 0 && (errno == EINTR || errno == EAGAIN));
  96         if (len < 0) {
  97                 fprintf(stderr, "netlink receive error %s (%d)\n",
  98                         strerror(errno), errno);
  99                 return -errno;
 100         }
 101         if (len == 0) {
 102                 fprintf(stderr, "EOF on netlink\n");
 103                 return -ENODATA;
 104         }
 105         return len;
 106 }
 107
 108 static int rtnl_recvmsg(int fd, struct msghdr *msg, char **answer)
 109 {
 110         struct iovec *iov = msg->msg_iov;
 111         char *buf;
 112         int len;
 113
 114         iov->iov_base = NULL;
 115         iov->iov_len = 0;
 116
 117         len = __rtnl_recvmsg(fd, msg, MSG_PEEK | MSG_TRUNC);
 118         if (len < 0)
 119                 return len;
 120         if (len < 32768)
 121                 len = 32768;
 122         buf = malloc(len);
 123         if (!buf) {
 124                 fprintf(stderr, "malloc error: not enough buffer\n");
 125                 return -ENOMEM;
 126         }
 127         iov->iov_base = buf;
 128         iov->iov_len = len;
 129         len = __rtnl_recvmsg(fd, msg, 0);
 130         if (len < 0) {
 131                 free(buf);
 132                 return len;
 133         }
 134         if (answer)
 135                 *answer = buf;
 136         else
 137                 free(buf);
 138         return len;
 139 }
 140
 141 static void rtnl_talk_error(struct nlmsghdr *h, struct nlmsgerr *err,
 142                             nl_ext_ack_fn_t errfn)
 143 {
 144         fprintf(stderr, "RTNETLINK answers: %s\n",
 145                 strerror(-err->error));
 146 }
 147
 148 static int __rtnl_talk_iov(struct rtnl_handle *rtnl, struct iovec *iov,
 149                            size_t iovlen, struct nlmsghdr **answer,
 150                            bool show_rtnl_err, nl_ext_ack_fn_t errfn)
 151 {
 152         struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK };
 153         struct iovec riov;
 154         struct msghdr msg = {
 155                 .msg_name       = &nladdr,
 156                 .msg_namelen    = sizeof(nladdr),
 157                 .msg_iov        = iov,
 158                 .msg_iovlen     = iovlen,
 159         };
 160         unsigned int seq = 0;
 161         struct nlmsghdr *h;
 162         int i, status;
 163         char *buf;
 164
 165         for (i = 0; i < iovlen; i++) {
 166                 h = iov[i].iov_base;
 167                 h->nlmsg_seq = seq = ++rtnl->seq;
 168                 if (answer == NULL)
 169                         h->nlmsg_flags |= NLM_F_ACK;
 170         }
 171         status = sendmsg(rtnl->fd, &msg, 0);
 172         if (status < 0) {
 173                 perror("Cannot talk to rtnetlink");
 174                 return -1;
 175         }
 176         /* change msg to use the response iov */
 177         msg.msg_iov = &riov;
 178         msg.msg_iovlen = 1;
 179         i = 0;
 180         while (1) {
 181 next:
 182                 status = rtnl_recvmsg(rtnl->fd, &msg, &buf);
 183                 ++i;
 184                 if (status < 0)
 185                         return status;
 186                 if (msg.msg_namelen != sizeof(nladdr)) {
 187                         fprintf(stderr,
 188                                 "Sender address length == %d!\n",
 189                                 msg.msg_namelen);
 190                         exit(1);
 191                 }
 192                 for (h = (struct nlmsghdr *)buf; status >= sizeof(*h); ) {
 193                         int len = h->nlmsg_len;
 194                         int l = len - sizeof(*h);
 195
 196                         if (l < 0 || len > status) {
 197                                 if (msg.msg_flags & MSG_TRUNC) {
 198                                         fprintf(stderr, "Truncated message!\n");
 199                                         free(buf);
 200                                         return -1;
 201                                 }
 202                                 fprintf(stderr,
 203                                         "Malformed message: len=%d!\n",
 204                                         len);
 205                                 exit(1);
 206                         }
 207                         if (nladdr.nl_pid != 0 ||
 208                             h->nlmsg_pid != rtnl->local.nl_pid ||
 209                             h->nlmsg_seq > seq || h->nlmsg_seq < seq - iovlen) {
 210                                 /* Don't forget to skip that message. */
 211                                 status -= NLMSG_ALIGN(len);
 212                                 h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
 213                                 continue;
 214                         }
 215                         if (h->nlmsg_type == NLMSG_ERROR) {
 216                                 struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(h);
 217                                 int error = err->error;
 218
 219                                 if (l < sizeof(struct nlmsgerr)) {
 220                                         fprintf(stderr, "ERROR truncated\n");
 221                                         free(buf);
 222                                         return -1;
 223                                 }
 224                                 if (error) {
 225                                         errno = -error;
 226                                         if (rtnl->proto != NETLINK_SOCK_DIAG &&
 227                                             show_rtnl_err)
 228                                                 rtnl_talk_error(h, err, errfn);
 229                                 }
 230                                 if (i < iovlen) {
 231                                         free(buf);
 232                                         goto next;
 233                                 }
 234                                 if (error) {
 235                                         free(buf);
 236                                         return -i;
 237                                 }
 238                                 if (answer)
 239                                         *answer = (struct nlmsghdr *)buf;
 240                                 else
 241                                         free(buf);
 242                                 return 0;
 243                         }
 244                         if (answer) {
 245                                 *answer = (struct nlmsghdr *)buf;
 246                                 return 0;
 247                         }
 248                         fprintf(stderr, "Unexpected reply!\n");
 249                         status -= NLMSG_ALIGN(len);
 250                         h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
 251                 }
 252                 free(buf);
 253                 if (msg.msg_flags & MSG_TRUNC) {
 254                         fprintf(stderr, "Message truncated!\n");
 255                         continue;
 256                 }
 257                 if (status) {
 258                         fprintf(stderr, "Remnant of size %d!\n", status);
 259                         exit(1);
 260                 }
 261         }
 262 }
 263
 264 static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
 265                        struct nlmsghdr **answer, bool show_rtnl_err,
 266                        nl_ext_ack_fn_t errfn)
 267 {
 268         struct iovec iov = {
 269                 .iov_base       = n,
 270                 .iov_len        = n->nlmsg_len,
 271         };
 272
 273         return __rtnl_talk_iov(rtnl, &iov, 1, answer, show_rtnl_err, errfn);
 274 }
 275
 276 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
 277               struct nlmsghdr **answer)
 278 {
 279         return __rtnl_talk(rtnl, n, answer, true, NULL);
 280 }
 281
 282 int addattr(struct nlmsghdr *n, int maxlen, int type)
 283 {
 284         return addattr_l(n, maxlen, type, NULL, 0);
 285 }
 286
 287 int addattr8(struct nlmsghdr *n, int maxlen, int type, __u8 data)
 288 {
 289         return addattr_l(n, maxlen, type, &data, sizeof(__u8));
 290 }
 291
 292 int addattr16(struct nlmsghdr *n, int maxlen, int type, __u16 data)
 293 {
 294         return addattr_l(n, maxlen, type, &data, sizeof(__u16));
 295 }
 296
 297 int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
 298 {
 299         return addattr_l(n, maxlen, type, &data, sizeof(__u32));
 300 }
 301
 302 int addattr64(struct nlmsghdr *n, int maxlen, int type, __u64 data)
 303 {
 304         return addattr_l(n, maxlen, type, &data, sizeof(__u64));
 305 }
 306
 307 int addattrstrz(struct nlmsghdr *n, int maxlen, int type, const char *str)
 308 {
 309         return addattr_l(n, maxlen, type, str, strlen(str)+1);
 310 }
 311
 312 int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
 313               int alen)
 314 {
 315         int len = RTA_LENGTH(alen);
 316         struct rtattr *rta;
 317
 318         if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
 319                 fprintf(stderr, "%s: Message exceeded bound of %d\n",
 320                         __func__, maxlen);
 321                 return -1;
 322         }
 323         rta = NLMSG_TAIL(n);
 324         rta->rta_type = type;
 325         rta->rta_len = len;
 326         if (alen)
 327                 memcpy(RTA_DATA(rta), data, alen);
 328         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
 329         return 0;
 330 }
 331
 332 int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
 333 {
 334         if (NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len) > maxlen) {
 335                 fprintf(stderr, "%s: Message exceeded bound of %d\n",
 336                         __func__, maxlen);
 337                 return -1;
 338         }
 339
 340         memcpy(NLMSG_TAIL(n), data, len);
 341         memset((void *) NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
 342         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
 343         return 0;
 344 }
 345
 346 struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type)
 347 {
 348         struct rtattr *nest = NLMSG_TAIL(n);
 349
 350         addattr_l(n, maxlen, type, NULL, 0);
 351         return nest;
 352 }
 353
 354 int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest)
 355 {
 356         nest->rta_len = (void *)NLMSG_TAIL(n) - (void *)nest;
 357         return n->nlmsg_len;
 358 }