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