tools/lib/bpf/netlink.c

   1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
   2 /* Copyright (c) 2018 Facebook */
   3
   4 #include <stdlib.h>
   5 #include <memory.h>
   6 #include <unistd.h>
   7 #include <linux/bpf.h>
   8 #include <linux/rtnetlink.h>
   9 #include <sys/socket.h>
  10 #include <errno.h>
  11 #include <time.h>
  12
  13 #include "bpf.h"
  14 #include "libbpf.h"
  15 #include "libbpf_internal.h"
  16 #include "nlattr.h"
  17
  18 /* make sure libbpf doesn't use kernel-only integer typedefs */
  19 #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
  20
  21 #ifndef SOL_NETLINK
  22 #define SOL_NETLINK 270
  23 #endif
  24
  25 typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, libbpf_dump_nlmsg_t,
  26                               void *cookie);
  27
  28 struct xdp_id_md {
  29         int ifindex;
  30         __u32 flags;
  31         struct xdp_link_info info;
  32 };
  33
  34 int libbpf_netlink_open(__u32 *nl_pid)
  35 {
  36         struct sockaddr_nl sa;
  37         socklen_t addrlen;
  38         int one = 1, ret;
  39         int sock;
  40
  41         memset(&sa, 0, sizeof(sa));
  42         sa.nl_family = AF_NETLINK;
  43
  44         sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  45         if (sock < 0)
  46                 return -errno;
  47
  48         if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
  49                        &one, sizeof(one)) < 0) {
  50                 pr_warn("Netlink error reporting not supported\n");
  51         }
  52
  53         if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
  54                 ret = -errno;
  55                 goto cleanup;
  56         }
  57
  58         addrlen = sizeof(sa);
  59         if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
  60                 ret = -errno;
  61                 goto cleanup;
  62         }
  63
  64         if (addrlen != sizeof(sa)) {
  65                 ret = -LIBBPF_ERRNO__INTERNAL;
  66                 goto cleanup;
  67         }
  68
  69         *nl_pid = sa.nl_pid;
  70         return sock;
  71
  72 cleanup:
  73         close(sock);
  74         return ret;
  75 }
  76
  77 static int bpf_netlink_recv(int sock, __u32 nl_pid, int seq,
  78                             __dump_nlmsg_t _fn, libbpf_dump_nlmsg_t fn,
  79                             void *cookie)
  80 {
  81         bool multipart = true;
  82         struct nlmsgerr *err;
  83         struct nlmsghdr *nh;
  84         char buf[4096];
  85         int len, ret;
  86
  87         while (multipart) {
  88                 multipart = false;
  89                 len = recv(sock, buf, sizeof(buf), 0);
  90                 if (len < 0) {
  91                         ret = -errno;
  92                         goto done;
  93                 }
  94
  95                 if (len == 0)
  96                         break;
  97
  98                 for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
  99                      nh = NLMSG_NEXT(nh, len)) {
 100                         if (nh->nlmsg_pid != nl_pid) {
 101                                 ret = -LIBBPF_ERRNO__WRNGPID;
 102                                 goto done;
 103                         }
 104                         if (nh->nlmsg_seq != seq) {
 105                                 ret = -LIBBPF_ERRNO__INVSEQ;
 106                                 goto done;
 107                         }
 108                         if (nh->nlmsg_flags & NLM_F_MULTI)
 109                                 multipart = true;
 110                         switch (nh->nlmsg_type) {
 111                         case NLMSG_ERROR:
 112                                 err = (struct nlmsgerr *)NLMSG_DATA(nh);
 113                                 if (!err->error)
 114                                         continue;
 115                                 ret = err->error;
 116                                 libbpf_nla_dump_errormsg(nh);
 117                                 goto done;
 118                         case NLMSG_DONE:
 119                                 return 0;
 120                         default:
 121                                 break;
 122                         }
 123                         if (_fn) {
 124                                 ret = _fn(nh, fn, cookie);
 125                                 if (ret)
 126                                         return ret;
 127                         }
 128                 }
 129         }
 130         ret = 0;
 131 done:
 132         return ret;
 133 }
 134
 135 int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
 136 {
 137         int sock, seq = 0, ret;
 138         struct nlattr *nla, *nla_xdp;
 139         struct {
 140                 struct nlmsghdr  nh;
 141                 struct ifinfomsg ifinfo;
 142                 char             attrbuf[64];
 143         } req;
 144         __u32 nl_pid;
 145
 146         sock = libbpf_netlink_open(&nl_pid);
 147         if (sock < 0)
 148                 return sock;
 149
 150         memset(&req, 0, sizeof(req));
 151         req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
 152         req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
 153         req.nh.nlmsg_type = RTM_SETLINK;
 154         req.nh.nlmsg_pid = 0;
 155         req.nh.nlmsg_seq = ++seq;
 156         req.ifinfo.ifi_family = AF_UNSPEC;
 157         req.ifinfo.ifi_index = ifindex;
 158
 159         /* started nested attribute for XDP */
 160         nla = (struct nlattr *)(((char *)&req)
 161                                 + NLMSG_ALIGN(req.nh.nlmsg_len));
 162         nla->nla_type = NLA_F_NESTED | IFLA_XDP;
 163         nla->nla_len = NLA_HDRLEN;
 164
 165         /* add XDP fd */
 166         nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
 167         nla_xdp->nla_type = IFLA_XDP_FD;
 168         nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);
 169         memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd));
 170         nla->nla_len += nla_xdp->nla_len;
 171
 172         /* if user passed in any flags, add those too */
 173         if (flags) {
 174                 nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
 175                 nla_xdp->nla_type = IFLA_XDP_FLAGS;
 176                 nla_xdp->nla_len = NLA_HDRLEN + sizeof(flags);
 177                 memcpy((char *)nla_xdp + NLA_HDRLEN, &flags, sizeof(flags));
 178                 nla->nla_len += nla_xdp->nla_len;
 179         }
 180
 181         req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);
 182
 183         if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {
 184                 ret = -errno;
 185                 goto cleanup;
 186         }
 187         ret = bpf_netlink_recv(sock, nl_pid, seq, NULL, NULL, NULL);
 188
 189 cleanup:
 190         close(sock);
 191         return ret;
 192 }
 193
 194 static int __dump_link_nlmsg(struct nlmsghdr *nlh,
 195                              libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
 196 {
 197         struct nlattr *tb[IFLA_MAX + 1], *attr;
 198         struct ifinfomsg *ifi = NLMSG_DATA(nlh);
 199         int len;
 200
 201         len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*ifi));
 202         attr = (struct nlattr *) ((void *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
 203         if (libbpf_nla_parse(tb, IFLA_MAX, attr, len, NULL) != 0)
 204                 return -LIBBPF_ERRNO__NLPARSE;
 205
 206         return dump_link_nlmsg(cookie, ifi, tb);
 207 }
 208
 209 static int get_xdp_info(void *cookie, void *msg, struct nlattr **tb)
 210 {
 211         struct nlattr *xdp_tb[IFLA_XDP_MAX + 1];
 212         struct xdp_id_md *xdp_id = cookie;
 213         struct ifinfomsg *ifinfo = msg;
 214         int ret;
 215
 216         if (xdp_id->ifindex && xdp_id->ifindex != ifinfo->ifi_index)
 217                 return 0;
 218
 219         if (!tb[IFLA_XDP])
 220                 return 0;
 221
 222         ret = libbpf_nla_parse_nested(xdp_tb, IFLA_XDP_MAX, tb[IFLA_XDP], NULL);
 223         if (ret)
 224                 return ret;
 225
 226         if (!xdp_tb[IFLA_XDP_ATTACHED])
 227                 return 0;
 228
 229         xdp_id->info.attach_mode = libbpf_nla_getattr_u8(
 230                 xdp_tb[IFLA_XDP_ATTACHED]);
 231
 232         if (xdp_id->info.attach_mode == XDP_ATTACHED_NONE)
 233                 return 0;
 234
 235         if (xdp_tb[IFLA_XDP_PROG_ID])
 236                 xdp_id->info.prog_id = libbpf_nla_getattr_u32(
 237                         xdp_tb[IFLA_XDP_PROG_ID]);
 238
 239         if (xdp_tb[IFLA_XDP_SKB_PROG_ID])
 240                 xdp_id->info.skb_prog_id = libbpf_nla_getattr_u32(
 241                         xdp_tb[IFLA_XDP_SKB_PROG_ID]);
 242
 243         if (xdp_tb[IFLA_XDP_DRV_PROG_ID])
 244                 xdp_id->info.drv_prog_id = libbpf_nla_getattr_u32(
 245                         xdp_tb[IFLA_XDP_DRV_PROG_ID]);
 246
 247         if (xdp_tb[IFLA_XDP_HW_PROG_ID])
 248                 xdp_id->info.hw_prog_id = libbpf_nla_getattr_u32(
 249                         xdp_tb[IFLA_XDP_HW_PROG_ID]);
 250
 251         return 0;
 252 }
 253
 254 int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info,
 255                           size_t info_size, __u32 flags)
 256 {
 257         struct xdp_id_md xdp_id = {};
 258         int sock, ret;
 259         __u32 nl_pid;
 260         __u32 mask;
 261
 262         if (flags & ~XDP_FLAGS_MASK || !info_size)
 263                 return -EINVAL;
 264
 265         /* Check whether the single {HW,DRV,SKB} mode is set */
 266         flags &= (XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE);
 267         mask = flags - 1;
 268         if (flags && flags & mask)
 269                 return -EINVAL;
 270
 271         sock = libbpf_netlink_open(&nl_pid);
 272         if (sock < 0)
 273                 return sock;
 274
 275         xdp_id.ifindex = ifindex;
 276         xdp_id.flags = flags;
 277
 278         ret = libbpf_nl_get_link(sock, nl_pid, get_xdp_info, &xdp_id);
 279         if (!ret) {
 280                 size_t sz = min(info_size, sizeof(xdp_id.info));
 281
 282                 memcpy(info, &xdp_id.info, sz);
 283                 memset((void *) info + sz, 0, info_size - sz);
 284         }
 285
 286         close(sock);
 287         return ret;
 288 }
 289
 290 static __u32 get_xdp_id(struct xdp_link_info *info, __u32 flags)
 291 {
 292         if (info->attach_mode != XDP_ATTACHED_MULTI)
 293                 return info->prog_id;
 294         if (flags & XDP_FLAGS_DRV_MODE)
 295                 return info->drv_prog_id;
 296         if (flags & XDP_FLAGS_HW_MODE)
 297                 return info->hw_prog_id;
 298         if (flags & XDP_FLAGS_SKB_MODE)
 299                 return info->skb_prog_id;
 300
 301         return 0;
 302 }
 303
 304 int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags)
 305 {
 306         struct xdp_link_info info;
 307         int ret;
 308
 309         ret = bpf_get_link_xdp_info(ifindex, &info, sizeof(info), flags);
 310         if (!ret)
 311                 *prog_id = get_xdp_id(&info, flags);
 312
 313         return ret;
 314 }
 315
 316 int libbpf_nl_get_link(int sock, unsigned int nl_pid,
 317                        libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
 318 {
 319         struct {
 320                 struct nlmsghdr nlh;
 321                 struct ifinfomsg ifm;
 322         } req = {
 323                 .nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
 324                 .nlh.nlmsg_type = RTM_GETLINK,
 325                 .nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 326                 .ifm.ifi_family = AF_PACKET,
 327         };
 328         int seq = time(NULL);
 329
 330         req.nlh.nlmsg_seq = seq;
 331         if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
 332                 return -errno;
 333
 334         return bpf_netlink_recv(sock, nl_pid, seq, __dump_link_nlmsg,
 335                                 dump_link_nlmsg, cookie);
 336 }
 337
 338 static int __dump_class_nlmsg(struct nlmsghdr *nlh,
 339                               libbpf_dump_nlmsg_t dump_class_nlmsg,
 340                               void *cookie)
 341 {
 342         struct nlattr *tb[TCA_MAX + 1], *attr;
 343         struct tcmsg *t = NLMSG_DATA(nlh);
 344         int len;
 345
 346         len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
 347         attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
 348         if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
 349                 return -LIBBPF_ERRNO__NLPARSE;
 350
 351         return dump_class_nlmsg(cookie, t, tb);
 352 }
 353
 354 int libbpf_nl_get_class(int sock, unsigned int nl_pid, int ifindex,
 355                         libbpf_dump_nlmsg_t dump_class_nlmsg, void *cookie)
 356 {
 357         struct {
 358                 struct nlmsghdr nlh;
 359                 struct tcmsg t;
 360         } req = {
 361                 .nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
 362                 .nlh.nlmsg_type = RTM_GETTCLASS,
 363                 .nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 364                 .t.tcm_family = AF_UNSPEC,
 365                 .t.tcm_ifindex = ifindex,
 366         };
 367         int seq = time(NULL);
 368
 369         req.nlh.nlmsg_seq = seq;
 370         if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
 371                 return -errno;
 372
 373         return bpf_netlink_recv(sock, nl_pid, seq, __dump_class_nlmsg,
 374                                 dump_class_nlmsg, cookie);
 375 }
 376
 377 static int __dump_qdisc_nlmsg(struct nlmsghdr *nlh,
 378                               libbpf_dump_nlmsg_t dump_qdisc_nlmsg,
 379                               void *cookie)
 380 {
 381         struct nlattr *tb[TCA_MAX + 1], *attr;
 382         struct tcmsg *t = NLMSG_DATA(nlh);
 383         int len;
 384
 385         len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
 386         attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
 387         if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
 388                 return -LIBBPF_ERRNO__NLPARSE;
 389
 390         return dump_qdisc_nlmsg(cookie, t, tb);
 391 }
 392
 393 int libbpf_nl_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
 394                         libbpf_dump_nlmsg_t dump_qdisc_nlmsg, void *cookie)
 395 {
 396         struct {
 397                 struct nlmsghdr nlh;
 398                 struct tcmsg t;
 399         } req = {
 400                 .nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
 401                 .nlh.nlmsg_type = RTM_GETQDISC,
 402                 .nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 403                 .t.tcm_family = AF_UNSPEC,
 404                 .t.tcm_ifindex = ifindex,
 405         };
 406         int seq = time(NULL);
 407
 408         req.nlh.nlmsg_seq = seq;
 409         if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
 410                 return -errno;
 411
 412         return bpf_netlink_recv(sock, nl_pid, seq, __dump_qdisc_nlmsg,
 413                                 dump_qdisc_nlmsg, cookie);
 414 }
 415
 416 static int __dump_filter_nlmsg(struct nlmsghdr *nlh,
 417                                libbpf_dump_nlmsg_t dump_filter_nlmsg,
 418                                void *cookie)
 419 {
 420         struct nlattr *tb[TCA_MAX + 1], *attr;
 421         struct tcmsg *t = NLMSG_DATA(nlh);
 422         int len;
 423
 424         len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
 425         attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
 426         if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
 427                 return -LIBBPF_ERRNO__NLPARSE;
 428
 429         return dump_filter_nlmsg(cookie, t, tb);
 430 }
 431
 432 int libbpf_nl_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
 433                          libbpf_dump_nlmsg_t dump_filter_nlmsg, void *cookie)
 434 {
 435         struct {
 436                 struct nlmsghdr nlh;
 437                 struct tcmsg t;
 438         } req = {
 439                 .nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
 440                 .nlh.nlmsg_type = RTM_GETTFILTER,
 441                 .nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 442                 .t.tcm_family = AF_UNSPEC,
 443                 .t.tcm_ifindex = ifindex,
 444                 .t.tcm_parent = handle,
 445         };
 446         int seq = time(NULL);
 447
 448         req.nlh.nlmsg_seq = seq;
 449         if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
 450                 return -errno;
 451
 452         return bpf_netlink_recv(sock, nl_pid, seq, __dump_filter_nlmsg,
 453                                 dump_filter_nlmsg, cookie);
 454 }