LXR linux/net/netfilter/nf_tables

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * (C) 2015 Red Hat GmbH
   4 * Author: Florian Westphal <fw@strlen.de>
   5 */
   6
   7#include <linux/module.h>
   8#include <linux/static_key.h>
   9#include <linux/hash.h>
  10#include <linux/jhash.h>
  11#include <linux/if_vlan.h>
  12#include <linux/init.h>
  13#include <linux/skbuff.h>
  14#include <linux/netlink.h>
  15#include <linux/netfilter.h>
  16#include <linux/netfilter/nfnetlink.h>
  17#include <linux/netfilter/nf_tables.h>
  18#include <net/netfilter/nf_tables_core.h>
  19#include <net/netfilter/nf_tables.h>
  20
  21#define NFT_TRACETYPE_LL_HSIZE          20
  22#define NFT_TRACETYPE_NETWORK_HSIZE     40
  23#define NFT_TRACETYPE_TRANSPORT_HSIZE   20
  24
  25DEFINE_STATIC_KEY_FALSE(nft_trace_enabled);
  26EXPORT_SYMBOL_GPL(nft_trace_enabled);
  27
  28static int trace_fill_id(struct sk_buff *nlskb, struct sk_buff *skb)
  29{
  30        __be32 id;
  31
  32        /* using skb address as ID results in a limited number of
  33         * values (and quick reuse).
  34         *
  35         * So we attempt to use as many skb members that will not
  36         * change while skb is with netfilter.
  37         */
  38        id = (__be32)jhash_2words(hash32_ptr(skb), skb_get_hash(skb),
  39                                  skb->skb_iif);
  40
  41        return nla_put_be32(nlskb, NFTA_TRACE_ID, id);
  42}
  43
  44static int trace_fill_header(struct sk_buff *nlskb, u16 type,
  45                             const struct sk_buff *skb,
  46                             int off, unsigned int len)
  47{
  48        struct nlattr *nla;
  49
  50        if (len == 0)
  51                return 0;
  52
  53        nla = nla_reserve(nlskb, type, len);
  54        if (!nla || skb_copy_bits(skb, off, nla_data(nla), len))
  55                return -1;
  56
  57        return 0;
  58}
  59
  60static int nf_trace_fill_ll_header(struct sk_buff *nlskb,
  61                                   const struct sk_buff *skb)
  62{
  63        struct vlan_ethhdr veth;
  64        int off;
  65
  66        BUILD_BUG_ON(sizeof(veth) > NFT_TRACETYPE_LL_HSIZE);
  67
  68        off = skb_mac_header(skb) - skb->data;
  69        if (off != -ETH_HLEN)
  70                return -1;
  71
  72        if (skb_copy_bits(skb, off, &veth, ETH_HLEN))
  73                return -1;
  74
  75        veth.h_vlan_proto = skb->vlan_proto;
  76        veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
  77        veth.h_vlan_encapsulated_proto = skb->protocol;
  78
  79        return nla_put(nlskb, NFTA_TRACE_LL_HEADER, sizeof(veth), &veth);
  80}
  81
  82static int nf_trace_fill_dev_info(struct sk_buff *nlskb,
  83                                  const struct net_device *indev,
  84                                  const struct net_device *outdev)
  85{
  86        if (indev) {
  87                if (nla_put_be32(nlskb, NFTA_TRACE_IIF,
  88                                 htonl(indev->ifindex)))
  89                        return -1;
  90
  91                if (nla_put_be16(nlskb, NFTA_TRACE_IIFTYPE,
  92                                 htons(indev->type)))
  93                        return -1;
  94        }
  95
  96        if (outdev) {
  97                if (nla_put_be32(nlskb, NFTA_TRACE_OIF,
  98                                 htonl(outdev->ifindex)))
  99                        return -1;
 100
 101                if (nla_put_be16(nlskb, NFTA_TRACE_OIFTYPE,
 102                                 htons(outdev->type)))
 103                        return -1;
 104        }
 105
 106        return 0;
 107}
 108
 109static int nf_trace_fill_pkt_info(struct sk_buff *nlskb,
 110                                  const struct nft_pktinfo *pkt)
 111{
 112        const struct sk_buff *skb = pkt->skb;
 113        int off = skb_network_offset(skb);
 114        unsigned int len, nh_end;
 115
 116        nh_end = pkt->tprot_set ? pkt->xt.thoff : skb->len;
 117        len = min_t(unsigned int, nh_end - skb_network_offset(skb),
 118                    NFT_TRACETYPE_NETWORK_HSIZE);
 119        if (trace_fill_header(nlskb, NFTA_TRACE_NETWORK_HEADER, skb, off, len))
 120                return -1;
 121
 122        if (pkt->tprot_set) {
 123                len = min_t(unsigned int, skb->len - pkt->xt.thoff,
 124                            NFT_TRACETYPE_TRANSPORT_HSIZE);
 125                if (trace_fill_header(nlskb, NFTA_TRACE_TRANSPORT_HEADER, skb,
 126                                      pkt->xt.thoff, len))
 127                        return -1;
 128        }
 129
 130        if (!skb_mac_header_was_set(skb))
 131                return 0;
 132
 133        if (skb_vlan_tag_get(skb))
 134                return nf_trace_fill_ll_header(nlskb, skb);
 135
 136        off = skb_mac_header(skb) - skb->data;
 137        len = min_t(unsigned int, -off, NFT_TRACETYPE_LL_HSIZE);
 138        return trace_fill_header(nlskb, NFTA_TRACE_LL_HEADER,
 139                                 skb, off, len);
 140}
 141
 142static int nf_trace_fill_rule_info(struct sk_buff *nlskb,
 143                                   const struct nft_traceinfo *info)
 144{
 145        if (!info->rule)
 146                return 0;
 147
 148        /* a continue verdict with ->type == RETURN means that this is
 149         * an implicit return (end of chain reached).
 150         *
 151         * Since no rule matched, the ->rule pointer is invalid.
 152         */
 153        if (info->type == NFT_TRACETYPE_RETURN &&
 154            info->verdict->code == NFT_CONTINUE)
 155                return 0;
 156
 157        return nla_put_be64(nlskb, NFTA_TRACE_RULE_HANDLE,
 158                            cpu_to_be64(info->rule->handle),
 159                            NFTA_TRACE_PAD);
 160}
 161
 162static bool nft_trace_have_verdict_chain(struct nft_traceinfo *info)
 163{
 164        switch (info->type) {
 165        case NFT_TRACETYPE_RETURN:
 166        case NFT_TRACETYPE_RULE:
 167                break;
 168        default:
 169                return false;
 170        }
 171
 172        switch (info->verdict->code) {
 173        case NFT_JUMP:
 174        case NFT_GOTO:
 175                break;
 176        default:
 177                return false;
 178        }
 179
 180        return true;
 181}
 182
 183void nft_trace_notify(struct nft_traceinfo *info)
 184{
 185        const struct nft_pktinfo *pkt = info->pkt;
 186        struct nfgenmsg *nfmsg;
 187        struct nlmsghdr *nlh;
 188        struct sk_buff *skb;
 189        unsigned int size;
 190        u16 event;
 191
 192        if (!nfnetlink_has_listeners(nft_net(pkt), NFNLGRP_NFTRACE))
 193                return;
 194
 195        size = nlmsg_total_size(sizeof(struct nfgenmsg)) +
 196                nla_total_size(strlen(info->chain->table->name)) +
 197                nla_total_size(strlen(info->chain->name)) +
 198                nla_total_size_64bit(sizeof(__be64)) +  /* rule handle */
 199                nla_total_size(sizeof(__be32)) +        /* trace type */
 200                nla_total_size(0) +                     /* VERDICT, nested */
 201                        nla_total_size(sizeof(u32)) +   /* verdict code */
 202                nla_total_size(sizeof(u32)) +           /* id */
 203                nla_total_size(NFT_TRACETYPE_LL_HSIZE) +
 204                nla_total_size(NFT_TRACETYPE_NETWORK_HSIZE) +
 205                nla_total_size(NFT_TRACETYPE_TRANSPORT_HSIZE) +
 206                nla_total_size(sizeof(u32)) +           /* iif */
 207                nla_total_size(sizeof(__be16)) +        /* iiftype */
 208                nla_total_size(sizeof(u32)) +           /* oif */
 209                nla_total_size(sizeof(__be16)) +        /* oiftype */
 210                nla_total_size(sizeof(u32)) +           /* mark */
 211                nla_total_size(sizeof(u32)) +           /* nfproto */
 212                nla_total_size(sizeof(u32));            /* policy */
 213
 214        if (nft_trace_have_verdict_chain(info))
 215                size += nla_total_size(strlen(info->verdict->chain->name)); /* jump target */
 216
 217        skb = nlmsg_new(size, GFP_ATOMIC);
 218        if (!skb)
 219                return;
 220
 221        event = nfnl_msg_type(NFNL_SUBSYS_NFTABLES, NFT_MSG_TRACE);
 222        nlh = nlmsg_put(skb, 0, 0, event, sizeof(struct nfgenmsg), 0);
 223        if (!nlh)
 224                goto nla_put_failure;
 225
 226        nfmsg = nlmsg_data(nlh);
 227        nfmsg->nfgen_family     = info->basechain->type->family;
 228        nfmsg->version          = NFNETLINK_V0;
 229        nfmsg->res_id           = 0;
 230
 231        if (nla_put_be32(skb, NFTA_TRACE_NFPROTO, htonl(nft_pf(pkt))))
 232                goto nla_put_failure;
 233
 234        if (nla_put_be32(skb, NFTA_TRACE_TYPE, htonl(info->type)))
 235                goto nla_put_failure;
 236
 237        if (trace_fill_id(skb, pkt->skb))
 238                goto nla_put_failure;
 239
 240        if (nla_put_string(skb, NFTA_TRACE_CHAIN, info->chain->name))
 241                goto nla_put_failure;
 242
 243        if (nla_put_string(skb, NFTA_TRACE_TABLE, info->chain->table->name))
 244                goto nla_put_failure;
 245
 246        if (nf_trace_fill_rule_info(skb, info))
 247                goto nla_put_failure;
 248
 249        switch (info->type) {
 250        case NFT_TRACETYPE_UNSPEC:
 251        case __NFT_TRACETYPE_MAX:
 252                break;
 253        case NFT_TRACETYPE_RETURN:
 254        case NFT_TRACETYPE_RULE:
 255                if (nft_verdict_dump(skb, NFTA_TRACE_VERDICT, info->verdict))
 256                        goto nla_put_failure;
 257                break;
 258        case NFT_TRACETYPE_POLICY:
 259                if (nla_put_be32(skb, NFTA_TRACE_POLICY,
 260                                 htonl(info->basechain->policy)))
 261                        goto nla_put_failure;
 262                break;
 263        }
 264
 265        if (pkt->skb->mark &&
 266            nla_put_be32(skb, NFTA_TRACE_MARK, htonl(pkt->skb->mark)))
 267                goto nla_put_failure;
 268
 269        if (!info->packet_dumped) {
 270                if (nf_trace_fill_dev_info(skb, nft_in(pkt), nft_out(pkt)))
 271                        goto nla_put_failure;
 272
 273                if (nf_trace_fill_pkt_info(skb, pkt))
 274                        goto nla_put_failure;
 275                info->packet_dumped = true;
 276        }
 277
 278        nlmsg_end(skb, nlh);
 279        nfnetlink_send(skb, nft_net(pkt), 0, NFNLGRP_NFTRACE, 0, GFP_ATOMIC);
 280        return;
 281
 282 nla_put_failure:
 283        WARN_ON_ONCE(1);
 284        kfree_skb(skb);
 285}
 286
 287void nft_trace_init(struct nft_traceinfo *info, const struct nft_pktinfo *pkt,
 288                    const struct nft_verdict *verdict,
 289                    const struct nft_chain *chain)
 290{
 291        info->basechain = nft_base_chain(chain);
 292        info->trace = true;
 293        info->packet_dumped = false;
 294        info->pkt = pkt;
 295        info->verdict = verdict;
 296}
 297