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                                       .flags = GENL_UNS_ADMIN_PERM },
  35 };
  36
  37 static struct genl_family psample_nl_family __ro_after_init;
  38
  39 static int psample_group_nl_fill(struct sk_buff *msg,
  40                                  struct psample_group *group,
  41                                  enum psample_command cmd, u32 portid, u32 seq,
  42                                  int flags)
  43 {
  44         void *hdr;
  45         int ret;
  46
  47         hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd);
  48         if (!hdr)
  49                 return -EMSGSIZE;
  50
  51         ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
  52         if (ret < 0)
  53                 goto error;
  54
  55         ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount);
  56         if (ret < 0)
  57                 goto error;
  58
  59         ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq);
  60         if (ret < 0)
  61                 goto error;
  62
  63         genlmsg_end(msg, hdr);
  64         return 0;
  65
  66 error:
  67         genlmsg_cancel(msg, hdr);
  68         return -EMSGSIZE;
  69 }
  70
  71 static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg,
  72                                            struct netlink_callback *cb)
  73 {
  74         struct psample_group *group;
  75         int start = cb->args[0];
  76         int idx = 0;
  77         int err;
  78
  79         spin_lock_bh(&psample_groups_lock);
  80         list_for_each_entry(group, &psample_groups_list, list) {
  81                 if (!net_eq(group->net, sock_net(msg->sk)))
  82                         continue;
  83                 if (idx < start) {
  84                         idx++;
  85                         continue;
  86                 }
  87                 err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP,
  88                                             NETLINK_CB(cb->skb).portid,
  89                                             cb->nlh->nlmsg_seq, NLM_F_MULTI);
  90                 if (err)
  91                         break;
  92                 idx++;
  93         }
  94
  95         spin_unlock_bh(&psample_groups_lock);
  96         cb->args[0] = idx;
  97         return msg->len;
  98 }
  99
 100 static const struct genl_small_ops psample_nl_ops[] = {
 101         {
 102                 .cmd = PSAMPLE_CMD_GET_GROUP,
 103                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 104                 .dumpit = psample_nl_cmd_get_group_dumpit,
 105                 /* can be retrieved by unprivileged users */
 106         }
 107 };
 108
 109 static struct genl_family psample_nl_family __ro_after_init = {
 110         .name           = PSAMPLE_GENL_NAME,
 111         .version        = PSAMPLE_GENL_VERSION,
 112         .maxattr        = PSAMPLE_ATTR_MAX,
 113         .netnsok        = true,
 114         .module         = THIS_MODULE,
 115         .mcgrps         = psample_nl_mcgrps,
 116         .small_ops      = psample_nl_ops,
 117         .n_small_ops    = ARRAY_SIZE(psample_nl_ops),
 118         .n_mcgrps       = ARRAY_SIZE(psample_nl_mcgrps),
 119 };
 120
 121 static void psample_group_notify(struct psample_group *group,
 122                                  enum psample_command cmd)
 123 {
 124         struct sk_buff *msg;
 125         int err;
 126
 127         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 128         if (!msg)
 129                 return;
 130
 131         err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI);
 132         if (!err)
 133                 genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0,
 134                                         PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC);
 135         else
 136                 nlmsg_free(msg);
 137 }
 138
 139 static struct psample_group *psample_group_create(struct net *net,
 140                                                   u32 group_num)
 141 {
 142         struct psample_group *group;
 143
 144         group = kzalloc(sizeof(*group), GFP_ATOMIC);
 145         if (!group)
 146                 return NULL;
 147
 148         group->net = net;
 149         group->group_num = group_num;
 150         list_add_tail(&group->list, &psample_groups_list);
 151
 152         psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP);
 153         return group;
 154 }
 155
 156 static void psample_group_destroy(struct psample_group *group)
 157 {
 158         psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP);
 159         list_del(&group->list);
 160         kfree_rcu(group, rcu);
 161 }
 162
 163 static struct psample_group *
 164 psample_group_lookup(struct net *net, u32 group_num)
 165 {
 166         struct psample_group *group;
 167
 168         list_for_each_entry(group, &psample_groups_list, list)
 169                 if ((group->group_num == group_num) && (group->net == net))
 170                         return group;
 171         return NULL;
 172 }
 173
 174 struct psample_group *psample_group_get(struct net *net, u32 group_num)
 175 {
 176         struct psample_group *group;
 177
 178         spin_lock_bh(&psample_groups_lock);
 179
 180         group = psample_group_lookup(net, group_num);
 181         if (!group) {
 182                 group = psample_group_create(net, group_num);
 183                 if (!group)
 184                         goto out;
 185         }
 186         group->refcount++;
 187
 188 out:
 189         spin_unlock_bh(&psample_groups_lock);
 190         return group;
 191 }
 192 EXPORT_SYMBOL_GPL(psample_group_get);
 193
 194 void psample_group_take(struct psample_group *group)
 195 {
 196         spin_lock_bh(&psample_groups_lock);
 197         group->refcount++;
 198         spin_unlock_bh(&psample_groups_lock);
 199 }
 200 EXPORT_SYMBOL_GPL(psample_group_take);
 201
 202 void psample_group_put(struct psample_group *group)
 203 {
 204         spin_lock_bh(&psample_groups_lock);
 205
 206         if (--group->refcount == 0)
 207                 psample_group_destroy(group);
 208
 209         spin_unlock_bh(&psample_groups_lock);
 210 }
 211 EXPORT_SYMBOL_GPL(psample_group_put);
 212
 213 #ifdef CONFIG_INET
 214 static int __psample_ip_tun_to_nlattr(struct sk_buff *skb,
 215                               struct ip_tunnel_info *tun_info)
 216 {
 217         unsigned short tun_proto = ip_tunnel_info_af(tun_info);
 218         const void *tun_opts = ip_tunnel_info_opts(tun_info);
 219         const struct ip_tunnel_key *tun_key = &tun_info->key;
 220         int tun_opts_len = tun_info->options_len;
 221
 222         if (tun_key->tun_flags & TUNNEL_KEY &&
 223             nla_put_be64(skb, PSAMPLE_TUNNEL_KEY_ATTR_ID, tun_key->tun_id,
 224                          PSAMPLE_TUNNEL_KEY_ATTR_PAD))
 225                 return -EMSGSIZE;
 226
 227         if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE &&
 228             nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_INFO_BRIDGE))
 229                 return -EMSGSIZE;
 230
 231         switch (tun_proto) {
 232         case AF_INET:
 233                 if (tun_key->u.ipv4.src &&
 234                     nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_SRC,
 235                                     tun_key->u.ipv4.src))
 236                         return -EMSGSIZE;
 237                 if (tun_key->u.ipv4.dst &&
 238                     nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_DST,
 239                                     tun_key->u.ipv4.dst))
 240                         return -EMSGSIZE;
 241                 break;
 242         case AF_INET6:
 243                 if (!ipv6_addr_any(&tun_key->u.ipv6.src) &&
 244                     nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_SRC,
 245                                      &tun_key->u.ipv6.src))
 246                         return -EMSGSIZE;
 247                 if (!ipv6_addr_any(&tun_key->u.ipv6.dst) &&
 248                     nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_DST,
 249                                      &tun_key->u.ipv6.dst))
 250                         return -EMSGSIZE;
 251                 break;
 252         }
 253         if (tun_key->tos &&
 254             nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TOS, tun_key->tos))
 255                 return -EMSGSIZE;
 256         if (nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TTL, tun_key->ttl))
 257                 return -EMSGSIZE;
 258         if ((tun_key->tun_flags & TUNNEL_DONT_FRAGMENT) &&
 259             nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_DONT_FRAGMENT))
 260                 return -EMSGSIZE;
 261         if ((tun_key->tun_flags & TUNNEL_CSUM) &&
 262             nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_CSUM))
 263                 return -EMSGSIZE;
 264         if (tun_key->tp_src &&
 265             nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_SRC, tun_key->tp_src))
 266                 return -EMSGSIZE;
 267         if (tun_key->tp_dst &&
 268             nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_DST, tun_key->tp_dst))
 269                 return -EMSGSIZE;
 270         if ((tun_key->tun_flags & TUNNEL_OAM) &&
 271             nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_OAM))
 272                 return -EMSGSIZE;
 273         if (tun_opts_len) {
 274                 if (tun_key->tun_flags & TUNNEL_GENEVE_OPT &&
 275                     nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_GENEVE_OPTS,
 276                             tun_opts_len, tun_opts))
 277                         return -EMSGSIZE;
 278                 else if (tun_key->tun_flags & TUNNEL_ERSPAN_OPT &&
 279                          nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_ERSPAN_OPTS,
 280                                  tun_opts_len, tun_opts))
 281                         return -EMSGSIZE;
 282         }
 283
 284         return 0;
 285 }
 286
 287 static int psample_ip_tun_to_nlattr(struct sk_buff *skb,
 288                             struct ip_tunnel_info *tun_info)
 289 {
 290         struct nlattr *nla;
 291         int err;
 292
 293         nla = nla_nest_start_noflag(skb, PSAMPLE_ATTR_TUNNEL);
 294         if (!nla)
 295                 return -EMSGSIZE;
 296
 297         err = __psample_ip_tun_to_nlattr(skb, tun_info);
 298         if (err) {
 299                 nla_nest_cancel(skb, nla);
 300                 return err;
 301         }
 302
 303         nla_nest_end(skb, nla);
 304
 305         return 0;
 306 }
 307
 308 static int psample_tunnel_meta_len(struct ip_tunnel_info *tun_info)
 309 {
 310         unsigned short tun_proto = ip_tunnel_info_af(tun_info);
 311         const struct ip_tunnel_key *tun_key = &tun_info->key;
 312         int tun_opts_len = tun_info->options_len;
 313         int sum = nla_total_size(0);    /* PSAMPLE_ATTR_TUNNEL */
 314
 315         if (tun_key->tun_flags & TUNNEL_KEY)
 316                 sum += nla_total_size_64bit(sizeof(u64));
 317
 318         if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE)
 319                 sum += nla_total_size(0);
 320
 321         switch (tun_proto) {
 322         case AF_INET:
 323                 if (tun_key->u.ipv4.src)
 324                         sum += nla_total_size(sizeof(u32));
 325                 if (tun_key->u.ipv4.dst)
 326                         sum += nla_total_size(sizeof(u32));
 327                 break;
 328         case AF_INET6:
 329                 if (!ipv6_addr_any(&tun_key->u.ipv6.src))
 330                         sum += nla_total_size(sizeof(struct in6_addr));
 331                 if (!ipv6_addr_any(&tun_key->u.ipv6.dst))
 332                         sum += nla_total_size(sizeof(struct in6_addr));
 333                 break;
 334         }
 335         if (tun_key->tos)
 336                 sum += nla_total_size(sizeof(u8));
 337         sum += nla_total_size(sizeof(u8));      /* TTL */
 338         if (tun_key->tun_flags & TUNNEL_DONT_FRAGMENT)
 339                 sum += nla_total_size(0);
 340         if (tun_key->tun_flags & TUNNEL_CSUM)
 341                 sum += nla_total_size(0);
 342         if (tun_key->tp_src)
 343                 sum += nla_total_size(sizeof(u16));
 344         if (tun_key->tp_dst)
 345                 sum += nla_total_size(sizeof(u16));
 346         if (tun_key->tun_flags & TUNNEL_OAM)
 347                 sum += nla_total_size(0);
 348         if (tun_opts_len) {
 349                 if (tun_key->tun_flags & TUNNEL_GENEVE_OPT)
 350                         sum += nla_total_size(tun_opts_len);
 351                 else if (tun_key->tun_flags & TUNNEL_ERSPAN_OPT)
 352                         sum += nla_total_size(tun_opts_len);
 353         }
 354
 355         return sum;
 356 }
 357 #endif
 358
 359 void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
 360                            u32 trunc_size, int in_ifindex, int out_ifindex,
 361                            u32 sample_rate)
 362 {
 363 #ifdef CONFIG_INET
 364         struct ip_tunnel_info *tun_info;
 365 #endif
 366         struct sk_buff *nl_skb;
 367         int data_len;
 368         int meta_len;
 369         void *data;
 370         int ret;
 371
 372         meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) +
 373                    (out_ifindex ? nla_total_size(sizeof(u16)) : 0) +
 374                    nla_total_size(sizeof(u32)) +        /* sample_rate */
 375                    nla_total_size(sizeof(u32)) +        /* orig_size */
 376                    nla_total_size(sizeof(u32)) +        /* group_num */
 377                    nla_total_size(sizeof(u32));         /* seq */
 378
 379 #ifdef CONFIG_INET
 380         tun_info = skb_tunnel_info(skb);
 381         if (tun_info)
 382                 meta_len += psample_tunnel_meta_len(tun_info);
 383 #endif
 384
 385         data_len = min(skb->len, trunc_size);
 386         if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)
 387                 data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN
 388                             - NLA_ALIGNTO;
 389
 390         nl_skb = genlmsg_new(meta_len + nla_total_size(data_len), GFP_ATOMIC);
 391         if (unlikely(!nl_skb))
 392                 return;
 393
 394         data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0,
 395                            PSAMPLE_CMD_SAMPLE);
 396         if (unlikely(!data))
 397                 goto error;
 398
 399         if (in_ifindex) {
 400                 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex);
 401                 if (unlikely(ret < 0))
 402                         goto error;
 403         }
 404
 405         if (out_ifindex) {
 406                 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex);
 407                 if (unlikely(ret < 0))
 408                         goto error;
 409         }
 410
 411         ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate);
 412         if (unlikely(ret < 0))
 413                 goto error;
 414
 415         ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len);
 416         if (unlikely(ret < 0))
 417                 goto error;
 418
 419         ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
 420         if (unlikely(ret < 0))
 421                 goto error;
 422
 423         ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++);
 424         if (unlikely(ret < 0))
 425                 goto error;
 426
 427         if (data_len) {
 428                 int nla_len = nla_total_size(data_len);
 429                 struct nlattr *nla;
 430
 431                 nla = skb_put(nl_skb, nla_len);
 432                 nla->nla_type = PSAMPLE_ATTR_DATA;
 433                 nla->nla_len = nla_attr_size(data_len);
 434
 435                 if (skb_copy_bits(skb, 0, nla_data(nla), data_len))
 436                         goto error;
 437         }
 438
 439 #ifdef CONFIG_INET
 440         if (tun_info) {
 441                 ret = psample_ip_tun_to_nlattr(nl_skb, tun_info);
 442                 if (unlikely(ret < 0))
 443                         goto error;
 444         }
 445 #endif
 446
 447         genlmsg_end(nl_skb, data);
 448         genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,
 449                                 PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC);
 450
 451         return;
 452 error:
 453         pr_err_ratelimited("Could not create psample log message\n");
 454         nlmsg_free(nl_skb);
 455 }
 456 EXPORT_SYMBOL_GPL(psample_sample_packet);
 457
 458 static int __init psample_module_init(void)
 459 {
 460         return genl_register_family(&psample_nl_family);
 461 }
 462
 463 static void __exit psample_module_exit(void)
 464 {
 465         genl_unregister_family(&psample_nl_family);
 466 }
 467
 468 module_init(psample_module_init);
 469 module_exit(psample_module_exit);
 470
 471 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 472 MODULE_DESCRIPTION("netlink channel for packet sampling");
 473 MODULE_LICENSE("GPL v2");