net/psample/psample.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * net/psample/psample.c - Netlink channel for packet sampling
   4  * Copyright (c) 2017 Yotam Gigi <[email protected]>
   5  */
   6
   7 #include <linux/types.h>
   8 #include <linux/kernel.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/module.h>
  11 #include <linux/timekeeping.h>
  12 #include <net/net_namespace.h>
  13 #include <net/sock.h>
  14 #include <net/netlink.h>
  15 #include <net/genetlink.h>
  16 #include <net/psample.h>
  17 #include <linux/spinlock.h>
  18 #include <net/ip_tunnels.h>
  19 #include <net/dst_metadata.h>
  20
  21 #define PSAMPLE_MAX_PACKET_SIZE 0xffff
  22
  23 static LIST_HEAD(psample_groups_list);
  24 static DEFINE_SPINLOCK(psample_groups_lock);
  25
  26 /* multicast groups */
  27 enum psample_nl_multicast_groups {
  28         PSAMPLE_NL_MCGRP_CONFIG,
  29         PSAMPLE_NL_MCGRP_SAMPLE,
  30 };
  31
  32 static const struct genl_multicast_group psample_nl_mcgrps[] = {
  33         [PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME },
  34         [PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME,
  35                                       .flags = GENL_MCAST_CAP_NET_ADMIN, },
  36 };
  37
  38 static struct genl_family psample_nl_family __ro_after_init;
  39
  40 static int psample_group_nl_fill(struct sk_buff *msg,
  41                                  struct psample_group *group,
  42                                  enum psample_command cmd, u32 portid, u32 seq,
  43                                  int flags)
  44 {
  45         void *hdr;
  46         int ret;
  47
  48         hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd);
  49         if (!hdr)
  50                 return -EMSGSIZE;
  51
  52         ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
  53         if (ret < 0)
  54                 goto error;
  55
  56         ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount);
  57         if (ret < 0)
  58                 goto error;
  59
  60         ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq);
  61         if (ret < 0)
  62                 goto error;
  63
  64         genlmsg_end(msg, hdr);
  65         return 0;
  66
  67 error:
  68         genlmsg_cancel(msg, hdr);
  69         return -EMSGSIZE;
  70 }
  71
  72 static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg,
  73                                            struct netlink_callback *cb)
  74 {
  75         struct psample_group *group;
  76         int start = cb->args[0];
  77         int idx = 0;
  78         int err;
  79
  80         spin_lock_bh(&psample_groups_lock);
  81         list_for_each_entry(group, &psample_groups_list, list) {
  82                 if (!net_eq(group->net, sock_net(msg->sk)))
  83                         continue;
  84                 if (idx < start) {
  85                         idx++;
  86                         continue;
  87                 }
  88                 err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP,
  89                                             NETLINK_CB(cb->skb).portid,
  90                                             cb->nlh->nlmsg_seq, NLM_F_MULTI);
  91                 if (err)
  92                         break;
  93                 idx++;
  94         }
  95
  96         spin_unlock_bh(&psample_groups_lock);
  97         cb->args[0] = idx;
  98         return msg->len;
  99 }
 100
 101 static const struct genl_small_ops psample_nl_ops[] = {
 102         {
 103                 .cmd = PSAMPLE_CMD_GET_GROUP,
 104                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 105                 .dumpit = psample_nl_cmd_get_group_dumpit,
 106                 /* can be retrieved by unprivileged users */
 107         }
 108 };
 109
 110 static struct genl_family psample_nl_family __ro_after_init = {
 111         .name           = PSAMPLE_GENL_NAME,
 112         .version        = PSAMPLE_GENL_VERSION,
 113         .maxattr        = PSAMPLE_ATTR_MAX,
 114         .netnsok        = true,
 115         .module         = THIS_MODULE,
 116         .mcgrps         = psample_nl_mcgrps,
 117         .small_ops      = psample_nl_ops,
 118         .n_small_ops    = ARRAY_SIZE(psample_nl_ops),
 119         .resv_start_op  = PSAMPLE_CMD_GET_GROUP + 1,
 120         .n_mcgrps       = ARRAY_SIZE(psample_nl_mcgrps),
 121 };
 122
 123 static void psample_group_notify(struct psample_group *group,
 124                                  enum psample_command cmd)
 125 {
 126         struct sk_buff *msg;
 127         int err;
 128
 129         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 130         if (!msg)
 131                 return;
 132
 133         err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI);
 134         if (!err)
 135                 genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0,
 136                                         PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC);
 137         else
 138                 nlmsg_free(msg);
 139 }
 140
 141 static struct psample_group *psample_group_create(struct net *net,
 142                                                   u32 group_num)
 143 {
 144         struct psample_group *group;
 145
 146         group = kzalloc(sizeof(*group), GFP_ATOMIC);
 147         if (!group)
 148                 return NULL;
 149
 150         group->net = net;
 151         group->group_num = group_num;
 152         list_add_tail(&group->list, &psample_groups_list);
 153
 154         psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP);
 155         return group;
 156 }
 157
 158 static void psample_group_destroy(struct psample_group *group)
 159 {
 160         psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP);
 161         list_del(&group->list);
 162         kfree_rcu(group, rcu);
 163 }
 164
 165 static struct psample_group *
 166 psample_group_lookup(struct net *net, u32 group_num)
 167 {
 168         struct psample_group *group;
 169
 170         list_for_each_entry(group, &psample_groups_list, list)
 171                 if ((group->group_num == group_num) && (group->net == net))
 172                         return group;
 173         return NULL;
 174 }
 175
 176 struct psample_group *psample_group_get(struct net *net, u32 group_num)
 177 {
 178         struct psample_group *group;
 179
 180         spin_lock_bh(&psample_groups_lock);
 181
 182         group = psample_group_lookup(net, group_num);
 183         if (!group) {
 184                 group = psample_group_create(net, group_num);
 185                 if (!group)
 186                         goto out;
 187         }
 188         group->refcount++;
 189
 190 out:
 191         spin_unlock_bh(&psample_groups_lock);
 192         return group;
 193 }
 194 EXPORT_SYMBOL_GPL(psample_group_get);
 195
 196 void psample_group_take(struct psample_group *group)
 197 {
 198         spin_lock_bh(&psample_groups_lock);
 199         group->refcount++;
 200         spin_unlock_bh(&psample_groups_lock);
 201 }
 202 EXPORT_SYMBOL_GPL(psample_group_take);
 203
 204 void psample_group_put(struct psample_group *group)
 205 {
 206         spin_lock_bh(&psample_groups_lock);
 207
 208         if (--group->refcount == 0)
 209                 psample_group_destroy(group);
 210
 211         spin_unlock_bh(&psample_groups_lock);
 212 }
 213 EXPORT_SYMBOL_GPL(psample_group_put);
 214
 215 #ifdef CONFIG_INET
 216 static int __psample_ip_tun_to_nlattr(struct sk_buff *skb,
 217                               struct ip_tunnel_info *tun_info)
 218 {
 219         unsigned short tun_proto = ip_tunnel_info_af(tun_info);
 220         const void *tun_opts = ip_tunnel_info_opts(tun_info);
 221         const struct ip_tunnel_key *tun_key = &tun_info->key;
 222         int tun_opts_len = tun_info->options_len;
 223
 224         if (test_bit(IP_TUNNEL_KEY_BIT, tun_key->tun_flags) &&
 225             nla_put_be64(skb, PSAMPLE_TUNNEL_KEY_ATTR_ID, tun_key->tun_id,
 226                          PSAMPLE_TUNNEL_KEY_ATTR_PAD))
 227                 return -EMSGSIZE;
 228
 229         if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE &&
 230             nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_INFO_BRIDGE))
 231                 return -EMSGSIZE;
 232
 233         switch (tun_proto) {
 234         case AF_INET:
 235                 if (tun_key->u.ipv4.src &&
 236                     nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_SRC,
 237                                     tun_key->u.ipv4.src))
 238                         return -EMSGSIZE;
 239                 if (tun_key->u.ipv4.dst &&
 240                     nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_DST,
 241                                     tun_key->u.ipv4.dst))
 242                         return -EMSGSIZE;
 243                 break;
 244         case AF_INET6:
 245                 if (!ipv6_addr_any(&tun_key->u.ipv6.src) &&
 246                     nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_SRC,
 247                                      &tun_key->u.ipv6.src))
 248                         return -EMSGSIZE;
 249                 if (!ipv6_addr_any(&tun_key->u.ipv6.dst) &&
 250                     nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_DST,
 251                                      &tun_key->u.ipv6.dst))
 252                         return -EMSGSIZE;
 253                 break;
 254         }
 255         if (tun_key->tos &&
 256             nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TOS, tun_key->tos))
 257                 return -EMSGSIZE;
 258         if (nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TTL, tun_key->ttl))
 259                 return -EMSGSIZE;
 260         if (test_bit(IP_TUNNEL_DONT_FRAGMENT_BIT, tun_key->tun_flags) &&
 261             nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_DONT_FRAGMENT))
 262                 return -EMSGSIZE;
 263         if (test_bit(IP_TUNNEL_CSUM_BIT, tun_key->tun_flags) &&
 264             nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_CSUM))
 265                 return -EMSGSIZE;
 266         if (tun_key->tp_src &&
 267             nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_SRC, tun_key->tp_src))
 268                 return -EMSGSIZE;
 269         if (tun_key->tp_dst &&
 270             nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_DST, tun_key->tp_dst))
 271                 return -EMSGSIZE;
 272         if (test_bit(IP_TUNNEL_OAM_BIT, tun_key->tun_flags) &&
 273             nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_OAM))
 274                 return -EMSGSIZE;
 275         if (tun_opts_len) {
 276                 if (test_bit(IP_TUNNEL_GENEVE_OPT_BIT, tun_key->tun_flags) &&
 277                     nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_GENEVE_OPTS,
 278                             tun_opts_len, tun_opts))
 279                         return -EMSGSIZE;
 280                 else if (test_bit(IP_TUNNEL_ERSPAN_OPT_BIT,
 281                                   tun_key->tun_flags) &&
 282                          nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_ERSPAN_OPTS,
 283                                  tun_opts_len, tun_opts))
 284                         return -EMSGSIZE;
 285         }
 286
 287         return 0;
 288 }
 289
 290 static int psample_ip_tun_to_nlattr(struct sk_buff *skb,
 291                             struct ip_tunnel_info *tun_info)
 292 {
 293         struct nlattr *nla;
 294         int err;
 295
 296         nla = nla_nest_start_noflag(skb, PSAMPLE_ATTR_TUNNEL);
 297         if (!nla)
 298                 return -EMSGSIZE;
 299
 300         err = __psample_ip_tun_to_nlattr(skb, tun_info);
 301         if (err) {
 302                 nla_nest_cancel(skb, nla);
 303                 return err;
 304         }
 305
 306         nla_nest_end(skb, nla);
 307
 308         return 0;
 309 }
 310
 311 static int psample_tunnel_meta_len(struct ip_tunnel_info *tun_info)
 312 {
 313         unsigned short tun_proto = ip_tunnel_info_af(tun_info);
 314         const struct ip_tunnel_key *tun_key = &tun_info->key;
 315         int tun_opts_len = tun_info->options_len;
 316         int sum = nla_total_size(0);    /* PSAMPLE_ATTR_TUNNEL */
 317
 318         if (test_bit(IP_TUNNEL_KEY_BIT, tun_key->tun_flags))
 319                 sum += nla_total_size_64bit(sizeof(u64));
 320
 321         if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE)
 322                 sum += nla_total_size(0);
 323
 324         switch (tun_proto) {
 325         case AF_INET:
 326                 if (tun_key->u.ipv4.src)
 327                         sum += nla_total_size(sizeof(u32));
 328                 if (tun_key->u.ipv4.dst)
 329                         sum += nla_total_size(sizeof(u32));
 330                 break;
 331         case AF_INET6:
 332                 if (!ipv6_addr_any(&tun_key->u.ipv6.src))
 333                         sum += nla_total_size(sizeof(struct in6_addr));
 334                 if (!ipv6_addr_any(&tun_key->u.ipv6.dst))
 335                         sum += nla_total_size(sizeof(struct in6_addr));
 336                 break;
 337         }
 338         if (tun_key->tos)
 339                 sum += nla_total_size(sizeof(u8));
 340         sum += nla_total_size(sizeof(u8));      /* TTL */
 341         if (test_bit(IP_TUNNEL_DONT_FRAGMENT_BIT, tun_key->tun_flags))
 342                 sum += nla_total_size(0);
 343         if (test_bit(IP_TUNNEL_CSUM_BIT, tun_key->tun_flags))
 344                 sum += nla_total_size(0);
 345         if (tun_key->tp_src)
 346                 sum += nla_total_size(sizeof(u16));
 347         if (tun_key->tp_dst)
 348                 sum += nla_total_size(sizeof(u16));
 349         if (test_bit(IP_TUNNEL_OAM_BIT, tun_key->tun_flags))
 350                 sum += nla_total_size(0);
 351         if (tun_opts_len) {
 352                 if (test_bit(IP_TUNNEL_GENEVE_OPT_BIT, tun_key->tun_flags))
 353                         sum += nla_total_size(tun_opts_len);
 354                 else if (test_bit(IP_TUNNEL_ERSPAN_OPT_BIT,
 355                                   tun_key->tun_flags))
 356                         sum += nla_total_size(tun_opts_len);
 357         }
 358
 359         return sum;
 360 }
 361 #endif
 362
 363 void psample_sample_packet(struct psample_group *group,
 364                            const struct sk_buff *skb, u32 sample_rate,
 365                            const struct psample_metadata *md)
 366 {
 367         ktime_t tstamp = ktime_get_real();
 368         int out_ifindex = md->out_ifindex;
 369         int in_ifindex = md->in_ifindex;
 370         u32 trunc_size = md->trunc_size;
 371 #ifdef CONFIG_INET
 372         struct ip_tunnel_info *tun_info;
 373 #endif
 374         struct sk_buff *nl_skb;
 375         int data_len;
 376         int meta_len;
 377         void *data;
 378         int ret;
 379
 380         if (!genl_has_listeners(&psample_nl_family, group->net,
 381                                 PSAMPLE_NL_MCGRP_SAMPLE))
 382                 return;
 383
 384         meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) +
 385                    (out_ifindex ? nla_total_size(sizeof(u16)) : 0) +
 386                    (md->out_tc_valid ? nla_total_size(sizeof(u16)) : 0) +
 387                    (md->out_tc_occ_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
 388                    (md->latency_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
 389                    nla_total_size(sizeof(u32)) +        /* sample_rate */
 390                    nla_total_size(sizeof(u32)) +        /* orig_size */
 391                    nla_total_size(sizeof(u32)) +        /* group_num */
 392                    nla_total_size(sizeof(u32)) +        /* seq */
 393                    nla_total_size_64bit(sizeof(u64)) +  /* timestamp */
 394                    nla_total_size(sizeof(u16)) +        /* protocol */
 395                    (md->user_cookie_len ?
 396                     nla_total_size(md->user_cookie_len) : 0) + /* user cookie */
 397                    (md->rate_as_probability ?
 398                     nla_total_size(0) : 0);     /* rate as probability */
 399
 400 #ifdef CONFIG_INET
 401         tun_info = skb_tunnel_info(skb);
 402         if (tun_info)
 403                 meta_len += psample_tunnel_meta_len(tun_info);
 404 #endif
 405
 406         data_len = min(skb->len, trunc_size);
 407         if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)
 408                 data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN
 409                             - NLA_ALIGNTO;
 410
 411         nl_skb = genlmsg_new(meta_len + nla_total_size(data_len), GFP_ATOMIC);
 412         if (unlikely(!nl_skb))
 413                 return;
 414
 415         data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0,
 416                            PSAMPLE_CMD_SAMPLE);
 417         if (unlikely(!data))
 418                 goto error;
 419
 420         if (in_ifindex) {
 421                 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex);
 422                 if (unlikely(ret < 0))
 423                         goto error;
 424         }
 425
 426         if (out_ifindex) {
 427                 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex);
 428                 if (unlikely(ret < 0))
 429                         goto error;
 430         }
 431
 432         ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate);
 433         if (unlikely(ret < 0))
 434                 goto error;
 435
 436         ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len);
 437         if (unlikely(ret < 0))
 438                 goto error;
 439
 440         ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
 441         if (unlikely(ret < 0))
 442                 goto error;
 443
 444         ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++);
 445         if (unlikely(ret < 0))
 446                 goto error;
 447
 448         if (md->out_tc_valid) {
 449                 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OUT_TC, md->out_tc);
 450                 if (unlikely(ret < 0))
 451                         goto error;
 452         }
 453
 454         if (md->out_tc_occ_valid) {
 455                 ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_OUT_TC_OCC,
 456                                         md->out_tc_occ, PSAMPLE_ATTR_PAD);
 457                 if (unlikely(ret < 0))
 458                         goto error;
 459         }
 460
 461         if (md->latency_valid) {
 462                 ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_LATENCY,
 463                                         md->latency, PSAMPLE_ATTR_PAD);
 464                 if (unlikely(ret < 0))
 465                         goto error;
 466         }
 467
 468         ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_TIMESTAMP,
 469                                 ktime_to_ns(tstamp), PSAMPLE_ATTR_PAD);
 470         if (unlikely(ret < 0))
 471                 goto error;
 472
 473         ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_PROTO,
 474                           be16_to_cpu(skb->protocol));
 475         if (unlikely(ret < 0))
 476                 goto error;
 477
 478         if (data_len) {
 479                 int nla_len = nla_total_size(data_len);
 480                 struct nlattr *nla;
 481
 482                 nla = skb_put(nl_skb, nla_len);
 483                 nla->nla_type = PSAMPLE_ATTR_DATA;
 484                 nla->nla_len = nla_attr_size(data_len);
 485
 486                 if (skb_copy_bits(skb, 0, nla_data(nla), data_len))
 487                         goto error;
 488         }
 489
 490 #ifdef CONFIG_INET
 491         if (tun_info) {
 492                 ret = psample_ip_tun_to_nlattr(nl_skb, tun_info);
 493                 if (unlikely(ret < 0))
 494                         goto error;
 495         }
 496 #endif
 497
 498         if (md->user_cookie && md->user_cookie_len &&
 499             nla_put(nl_skb, PSAMPLE_ATTR_USER_COOKIE, md->user_cookie_len,
 500                     md->user_cookie))
 501                 goto error;
 502
 503         if (md->rate_as_probability &&
 504             nla_put_flag(nl_skb, PSAMPLE_ATTR_SAMPLE_PROBABILITY))
 505                 goto error;
 506
 507         genlmsg_end(nl_skb, data);
 508         genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,
 509                                 PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC);
 510
 511         return;
 512 error:
 513         pr_err_ratelimited("Could not create psample log message\n");
 514         nlmsg_free(nl_skb);
 515 }
 516 EXPORT_SYMBOL_GPL(psample_sample_packet);
 517
 518 static int __init psample_module_init(void)
 519 {
 520         return genl_register_family(&psample_nl_family);
 521 }
 522
 523 static void __exit psample_module_exit(void)
 524 {
 525         genl_unregister_family(&psample_nl_family);
 526 }
 527
 528 module_init(psample_module_init);
 529 module_exit(psample_module_exit);
 530
 531 MODULE_AUTHOR("Yotam Gigi <[email protected]>");
 532 MODULE_DESCRIPTION("netlink channel for packet sampling");
 533 MODULE_LICENSE("GPL v2");