net/netfilter/nft_xfrm.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  * Generic part shared by ipv4 and ipv6 backends.
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/init.h>
   9 #include <linux/module.h>
  10 #include <linux/netlink.h>
  11 #include <linux/netfilter.h>
  12 #include <linux/netfilter/nf_tables.h>
  13 #include <net/netfilter/nf_tables_core.h>
  14 #include <net/netfilter/nf_tables.h>
  15 #include <linux/in.h>
  16 #include <net/xfrm.h>
  17
  18 static const struct nla_policy nft_xfrm_policy[NFTA_XFRM_MAX + 1] = {
  19         [NFTA_XFRM_KEY]         = NLA_POLICY_MAX(NLA_BE32, 255),
  20         [NFTA_XFRM_DIR]         = { .type = NLA_U8 },
  21         [NFTA_XFRM_SPNUM]       = NLA_POLICY_MAX(NLA_BE32, 255),
  22         [NFTA_XFRM_DREG]        = { .type = NLA_U32 },
  23 };
  24
  25 struct nft_xfrm {
  26         enum nft_xfrm_keys      key:8;
  27         u8                      dreg;
  28         u8                      dir;
  29         u8                      spnum;
  30         u8                      len;
  31 };
  32
  33 static int nft_xfrm_get_init(const struct nft_ctx *ctx,
  34                              const struct nft_expr *expr,
  35                              const struct nlattr * const tb[])
  36 {
  37         struct nft_xfrm *priv = nft_expr_priv(expr);
  38         unsigned int len = 0;
  39         u32 spnum = 0;
  40         u8 dir;
  41
  42         if (!tb[NFTA_XFRM_KEY] || !tb[NFTA_XFRM_DIR] || !tb[NFTA_XFRM_DREG])
  43                 return -EINVAL;
  44
  45         switch (ctx->family) {
  46         case NFPROTO_IPV4:
  47         case NFPROTO_IPV6:
  48         case NFPROTO_INET:
  49                 break;
  50         default:
  51                 return -EOPNOTSUPP;
  52         }
  53
  54         priv->key = ntohl(nla_get_be32(tb[NFTA_XFRM_KEY]));
  55         switch (priv->key) {
  56         case NFT_XFRM_KEY_REQID:
  57         case NFT_XFRM_KEY_SPI:
  58                 len = sizeof(u32);
  59                 break;
  60         case NFT_XFRM_KEY_DADDR_IP4:
  61         case NFT_XFRM_KEY_SADDR_IP4:
  62                 len = sizeof(struct in_addr);
  63                 break;
  64         case NFT_XFRM_KEY_DADDR_IP6:
  65         case NFT_XFRM_KEY_SADDR_IP6:
  66                 len = sizeof(struct in6_addr);
  67                 break;
  68         default:
  69                 return -EINVAL;
  70         }
  71
  72         dir = nla_get_u8(tb[NFTA_XFRM_DIR]);
  73         switch (dir) {
  74         case XFRM_POLICY_IN:
  75         case XFRM_POLICY_OUT:
  76                 priv->dir = dir;
  77                 break;
  78         default:
  79                 return -EINVAL;
  80         }
  81
  82         if (tb[NFTA_XFRM_SPNUM])
  83                 spnum = ntohl(nla_get_be32(tb[NFTA_XFRM_SPNUM]));
  84
  85         if (spnum >= XFRM_MAX_DEPTH)
  86                 return -ERANGE;
  87
  88         priv->spnum = spnum;
  89
  90         priv->len = len;
  91         return nft_parse_register_store(ctx, tb[NFTA_XFRM_DREG], &priv->dreg,
  92                                         NULL, NFT_DATA_VALUE, len);
  93 }
  94
  95 /* Return true if key asks for daddr/saddr and current
  96  * state does have a valid address (BEET, TUNNEL).
  97  */
  98 static bool xfrm_state_addr_ok(enum nft_xfrm_keys k, u8 family, u8 mode)
  99 {
 100         switch (k) {
 101         case NFT_XFRM_KEY_DADDR_IP4:
 102         case NFT_XFRM_KEY_SADDR_IP4:
 103                 if (family == NFPROTO_IPV4)
 104                         break;
 105                 return false;
 106         case NFT_XFRM_KEY_DADDR_IP6:
 107         case NFT_XFRM_KEY_SADDR_IP6:
 108                 if (family == NFPROTO_IPV6)
 109                         break;
 110                 return false;
 111         default:
 112                 return true;
 113         }
 114
 115         return mode == XFRM_MODE_BEET || mode == XFRM_MODE_TUNNEL;
 116 }
 117
 118 static void nft_xfrm_state_get_key(const struct nft_xfrm *priv,
 119                                    struct nft_regs *regs,
 120                                    const struct xfrm_state *state)
 121 {
 122         u32 *dest = &regs->data[priv->dreg];
 123
 124         if (!xfrm_state_addr_ok(priv->key,
 125                                 state->props.family,
 126                                 state->props.mode)) {
 127                 regs->verdict.code = NFT_BREAK;
 128                 return;
 129         }
 130
 131         switch (priv->key) {
 132         case NFT_XFRM_KEY_UNSPEC:
 133         case __NFT_XFRM_KEY_MAX:
 134                 WARN_ON_ONCE(1);
 135                 break;
 136         case NFT_XFRM_KEY_DADDR_IP4:
 137                 *dest = (__force __u32)state->id.daddr.a4;
 138                 return;
 139         case NFT_XFRM_KEY_DADDR_IP6:
 140                 memcpy(dest, &state->id.daddr.in6, sizeof(struct in6_addr));
 141                 return;
 142         case NFT_XFRM_KEY_SADDR_IP4:
 143                 *dest = (__force __u32)state->props.saddr.a4;
 144                 return;
 145         case NFT_XFRM_KEY_SADDR_IP6:
 146                 memcpy(dest, &state->props.saddr.in6, sizeof(struct in6_addr));
 147                 return;
 148         case NFT_XFRM_KEY_REQID:
 149                 *dest = state->props.reqid;
 150                 return;
 151         case NFT_XFRM_KEY_SPI:
 152                 *dest = (__force __u32)state->id.spi;
 153                 return;
 154         }
 155
 156         regs->verdict.code = NFT_BREAK;
 157 }
 158
 159 static void nft_xfrm_get_eval_in(const struct nft_xfrm *priv,
 160                                     struct nft_regs *regs,
 161                                     const struct nft_pktinfo *pkt)
 162 {
 163         const struct sec_path *sp = skb_sec_path(pkt->skb);
 164         const struct xfrm_state *state;
 165
 166         if (sp == NULL || sp->len <= priv->spnum) {
 167                 regs->verdict.code = NFT_BREAK;
 168                 return;
 169         }
 170
 171         state = sp->xvec[priv->spnum];
 172         nft_xfrm_state_get_key(priv, regs, state);
 173 }
 174
 175 static void nft_xfrm_get_eval_out(const struct nft_xfrm *priv,
 176                                   struct nft_regs *regs,
 177                                   const struct nft_pktinfo *pkt)
 178 {
 179         const struct dst_entry *dst = skb_dst(pkt->skb);
 180         int i;
 181
 182         for (i = 0; dst && dst->xfrm;
 183              dst = ((const struct xfrm_dst *)dst)->child, i++) {
 184                 if (i < priv->spnum)
 185                         continue;
 186
 187                 nft_xfrm_state_get_key(priv, regs, dst->xfrm);
 188                 return;
 189         }
 190
 191         regs->verdict.code = NFT_BREAK;
 192 }
 193
 194 static void nft_xfrm_get_eval(const struct nft_expr *expr,
 195                               struct nft_regs *regs,
 196                               const struct nft_pktinfo *pkt)
 197 {
 198         const struct nft_xfrm *priv = nft_expr_priv(expr);
 199
 200         switch (priv->dir) {
 201         case XFRM_POLICY_IN:
 202                 nft_xfrm_get_eval_in(priv, regs, pkt);
 203                 break;
 204         case XFRM_POLICY_OUT:
 205                 nft_xfrm_get_eval_out(priv, regs, pkt);
 206                 break;
 207         default:
 208                 WARN_ON_ONCE(1);
 209                 regs->verdict.code = NFT_BREAK;
 210                 break;
 211         }
 212 }
 213
 214 static int nft_xfrm_get_dump(struct sk_buff *skb,
 215                              const struct nft_expr *expr, bool reset)
 216 {
 217         const struct nft_xfrm *priv = nft_expr_priv(expr);
 218
 219         if (nft_dump_register(skb, NFTA_XFRM_DREG, priv->dreg))
 220                 return -1;
 221
 222         if (nla_put_be32(skb, NFTA_XFRM_KEY, htonl(priv->key)))
 223                 return -1;
 224         if (nla_put_u8(skb, NFTA_XFRM_DIR, priv->dir))
 225                 return -1;
 226         if (nla_put_be32(skb, NFTA_XFRM_SPNUM, htonl(priv->spnum)))
 227                 return -1;
 228
 229         return 0;
 230 }
 231
 232 static int nft_xfrm_validate(const struct nft_ctx *ctx, const struct nft_expr *expr)
 233 {
 234         const struct nft_xfrm *priv = nft_expr_priv(expr);
 235         unsigned int hooks;
 236
 237         if (ctx->family != NFPROTO_IPV4 &&
 238             ctx->family != NFPROTO_IPV6 &&
 239             ctx->family != NFPROTO_INET)
 240                 return -EOPNOTSUPP;
 241
 242         switch (priv->dir) {
 243         case XFRM_POLICY_IN:
 244                 hooks = (1 << NF_INET_FORWARD) |
 245                         (1 << NF_INET_LOCAL_IN) |
 246                         (1 << NF_INET_PRE_ROUTING);
 247                 break;
 248         case XFRM_POLICY_OUT:
 249                 hooks = (1 << NF_INET_FORWARD) |
 250                         (1 << NF_INET_LOCAL_OUT) |
 251                         (1 << NF_INET_POST_ROUTING);
 252                 break;
 253         default:
 254                 WARN_ON_ONCE(1);
 255                 return -EINVAL;
 256         }
 257
 258         return nft_chain_validate_hooks(ctx->chain, hooks);
 259 }
 260
 261 static bool nft_xfrm_reduce(struct nft_regs_track *track,
 262                             const struct nft_expr *expr)
 263 {
 264         const struct nft_xfrm *priv = nft_expr_priv(expr);
 265         const struct nft_xfrm *xfrm;
 266
 267         if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
 268                 nft_reg_track_update(track, expr, priv->dreg, priv->len);
 269                 return false;
 270         }
 271
 272         xfrm = nft_expr_priv(track->regs[priv->dreg].selector);
 273         if (priv->key != xfrm->key ||
 274             priv->dreg != xfrm->dreg ||
 275             priv->dir != xfrm->dir ||
 276             priv->spnum != xfrm->spnum) {
 277                 nft_reg_track_update(track, expr, priv->dreg, priv->len);
 278                 return false;
 279         }
 280
 281         if (!track->regs[priv->dreg].bitwise)
 282                 return true;
 283
 284         return nft_expr_reduce_bitwise(track, expr);
 285 }
 286
 287 static struct nft_expr_type nft_xfrm_type;
 288 static const struct nft_expr_ops nft_xfrm_get_ops = {
 289         .type           = &nft_xfrm_type,
 290         .size           = NFT_EXPR_SIZE(sizeof(struct nft_xfrm)),
 291         .eval           = nft_xfrm_get_eval,
 292         .init           = nft_xfrm_get_init,
 293         .dump           = nft_xfrm_get_dump,
 294         .validate       = nft_xfrm_validate,
 295         .reduce         = nft_xfrm_reduce,
 296 };
 297
 298 static struct nft_expr_type nft_xfrm_type __read_mostly = {
 299         .name           = "xfrm",
 300         .ops            = &nft_xfrm_get_ops,
 301         .policy         = nft_xfrm_policy,
 302         .maxattr        = NFTA_XFRM_MAX,
 303         .owner          = THIS_MODULE,
 304 };
 305
 306 static int __init nft_xfrm_module_init(void)
 307 {
 308         return nft_register_expr(&nft_xfrm_type);
 309 }
 310
 311 static void __exit nft_xfrm_module_exit(void)
 312 {
 313         nft_unregister_expr(&nft_xfrm_type);
 314 }
 315
 316 module_init(nft_xfrm_module_init);
 317 module_exit(nft_xfrm_module_exit);
 318
 319 MODULE_LICENSE("GPL");
 320 MODULE_DESCRIPTION("nf_tables: xfrm/IPSec matching");
 321 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
 322 MODULE_AUTHOR("Máté Eckl <ecklm94@gmail.com>");
 323 MODULE_ALIAS_NFT_EXPR("xfrm");