net/netfilter/nft_hash.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2016 Laura Garcia <nevola@gmail.com>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/init.h>
   8 #include <linux/module.h>
   9 #include <linux/netlink.h>
  10 #include <linux/netfilter.h>
  11 #include <linux/netfilter/nf_tables.h>
  12 #include <net/netfilter/nf_tables.h>
  13 #include <net/netfilter/nf_tables_core.h>
  14 #include <linux/jhash.h>
  15
  16 struct nft_jhash {
  17         u8                      sreg;
  18         u8                      dreg;
  19         u8                      len;
  20         bool                    autogen_seed:1;
  21         u32                     modulus;
  22         u32                     seed;
  23         u32                     offset;
  24 };
  25
  26 static void nft_jhash_eval(const struct nft_expr *expr,
  27                            struct nft_regs *regs,
  28                            const struct nft_pktinfo *pkt)
  29 {
  30         struct nft_jhash *priv = nft_expr_priv(expr);
  31         const void *data = &regs->data[priv->sreg];
  32         u32 h;
  33
  34         h = reciprocal_scale(jhash(data, priv->len, priv->seed),
  35                              priv->modulus);
  36
  37         regs->data[priv->dreg] = h + priv->offset;
  38 }
  39
  40 struct nft_symhash {
  41         u8                      dreg;
  42         u32                     modulus;
  43         u32                     offset;
  44 };
  45
  46 static void nft_symhash_eval(const struct nft_expr *expr,
  47                              struct nft_regs *regs,
  48                              const struct nft_pktinfo *pkt)
  49 {
  50         struct nft_symhash *priv = nft_expr_priv(expr);
  51         struct sk_buff *skb = pkt->skb;
  52         u32 h;
  53
  54         h = reciprocal_scale(__skb_get_hash_symmetric_net(nft_net(pkt), skb),
  55                              priv->modulus);
  56
  57         regs->data[priv->dreg] = h + priv->offset;
  58 }
  59
  60 static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
  61         [NFTA_HASH_SREG]        = { .type = NLA_U32 },
  62         [NFTA_HASH_DREG]        = { .type = NLA_U32 },
  63         [NFTA_HASH_LEN]         = NLA_POLICY_MAX(NLA_BE32, 255),
  64         [NFTA_HASH_MODULUS]     = { .type = NLA_U32 },
  65         [NFTA_HASH_SEED]        = { .type = NLA_U32 },
  66         [NFTA_HASH_OFFSET]      = { .type = NLA_U32 },
  67         [NFTA_HASH_TYPE]        = { .type = NLA_U32 },
  68 };
  69
  70 static int nft_jhash_init(const struct nft_ctx *ctx,
  71                           const struct nft_expr *expr,
  72                           const struct nlattr * const tb[])
  73 {
  74         struct nft_jhash *priv = nft_expr_priv(expr);
  75         u32 len;
  76         int err;
  77
  78         if (!tb[NFTA_HASH_SREG] ||
  79             !tb[NFTA_HASH_DREG] ||
  80             !tb[NFTA_HASH_LEN]  ||
  81             !tb[NFTA_HASH_MODULUS])
  82                 return -EINVAL;
  83
  84         if (tb[NFTA_HASH_OFFSET])
  85                 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
  86
  87         err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len);
  88         if (err < 0)
  89                 return err;
  90         if (len == 0)
  91                 return -ERANGE;
  92
  93         priv->len = len;
  94
  95         err = nft_parse_register_load(ctx, tb[NFTA_HASH_SREG], &priv->sreg, len);
  96         if (err < 0)
  97                 return err;
  98
  99         priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
 100         if (priv->modulus < 1)
 101                 return -ERANGE;
 102
 103         if (priv->offset + priv->modulus - 1 < priv->offset)
 104                 return -EOVERFLOW;
 105
 106         if (tb[NFTA_HASH_SEED]) {
 107                 priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
 108         } else {
 109                 priv->autogen_seed = true;
 110                 get_random_bytes(&priv->seed, sizeof(priv->seed));
 111         }
 112
 113         return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG], &priv->dreg,
 114                                         NULL, NFT_DATA_VALUE, sizeof(u32));
 115 }
 116
 117 static int nft_symhash_init(const struct nft_ctx *ctx,
 118                             const struct nft_expr *expr,
 119                             const struct nlattr * const tb[])
 120 {
 121         struct nft_symhash *priv = nft_expr_priv(expr);
 122
 123         if (!tb[NFTA_HASH_DREG]    ||
 124             !tb[NFTA_HASH_MODULUS])
 125                 return -EINVAL;
 126
 127         if (tb[NFTA_HASH_OFFSET])
 128                 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
 129
 130         priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
 131         if (priv->modulus < 1)
 132                 return -ERANGE;
 133
 134         if (priv->offset + priv->modulus - 1 < priv->offset)
 135                 return -EOVERFLOW;
 136
 137         return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG],
 138                                         &priv->dreg, NULL, NFT_DATA_VALUE,
 139                                         sizeof(u32));
 140 }
 141
 142 static int nft_jhash_dump(struct sk_buff *skb,
 143                           const struct nft_expr *expr, bool reset)
 144 {
 145         const struct nft_jhash *priv = nft_expr_priv(expr);
 146
 147         if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
 148                 goto nla_put_failure;
 149         if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
 150                 goto nla_put_failure;
 151         if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
 152                 goto nla_put_failure;
 153         if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
 154                 goto nla_put_failure;
 155         if (!priv->autogen_seed &&
 156             nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
 157                 goto nla_put_failure;
 158         if (priv->offset != 0)
 159                 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
 160                         goto nla_put_failure;
 161         if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS)))
 162                 goto nla_put_failure;
 163         return 0;
 164
 165 nla_put_failure:
 166         return -1;
 167 }
 168
 169 static bool nft_jhash_reduce(struct nft_regs_track *track,
 170                              const struct nft_expr *expr)
 171 {
 172         const struct nft_jhash *priv = nft_expr_priv(expr);
 173
 174         nft_reg_track_cancel(track, priv->dreg, sizeof(u32));
 175
 176         return false;
 177 }
 178
 179 static int nft_symhash_dump(struct sk_buff *skb,
 180                             const struct nft_expr *expr, bool reset)
 181 {
 182         const struct nft_symhash *priv = nft_expr_priv(expr);
 183
 184         if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
 185                 goto nla_put_failure;
 186         if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
 187                 goto nla_put_failure;
 188         if (priv->offset != 0)
 189                 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
 190                         goto nla_put_failure;
 191         if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM)))
 192                 goto nla_put_failure;
 193         return 0;
 194
 195 nla_put_failure:
 196         return -1;
 197 }
 198
 199 static bool nft_symhash_reduce(struct nft_regs_track *track,
 200                                const struct nft_expr *expr)
 201 {
 202         struct nft_symhash *priv = nft_expr_priv(expr);
 203         struct nft_symhash *symhash;
 204
 205         if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
 206                 nft_reg_track_update(track, expr, priv->dreg, sizeof(u32));
 207                 return false;
 208         }
 209
 210         symhash = nft_expr_priv(track->regs[priv->dreg].selector);
 211         if (priv->offset != symhash->offset ||
 212             priv->modulus != symhash->modulus) {
 213                 nft_reg_track_update(track, expr, priv->dreg, sizeof(u32));
 214                 return false;
 215         }
 216
 217         if (!track->regs[priv->dreg].bitwise)
 218                 return true;
 219
 220         return false;
 221 }
 222
 223 static struct nft_expr_type nft_hash_type;
 224 static const struct nft_expr_ops nft_jhash_ops = {
 225         .type           = &nft_hash_type,
 226         .size           = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
 227         .eval           = nft_jhash_eval,
 228         .init           = nft_jhash_init,
 229         .dump           = nft_jhash_dump,
 230         .reduce         = nft_jhash_reduce,
 231 };
 232
 233 static const struct nft_expr_ops nft_symhash_ops = {
 234         .type           = &nft_hash_type,
 235         .size           = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
 236         .eval           = nft_symhash_eval,
 237         .init           = nft_symhash_init,
 238         .dump           = nft_symhash_dump,
 239         .reduce         = nft_symhash_reduce,
 240 };
 241
 242 static const struct nft_expr_ops *
 243 nft_hash_select_ops(const struct nft_ctx *ctx,
 244                     const struct nlattr * const tb[])
 245 {
 246         u32 type;
 247
 248         if (!tb[NFTA_HASH_TYPE])
 249                 return &nft_jhash_ops;
 250
 251         type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
 252         switch (type) {
 253         case NFT_HASH_SYM:
 254                 return &nft_symhash_ops;
 255         case NFT_HASH_JENKINS:
 256                 return &nft_jhash_ops;
 257         default:
 258                 break;
 259         }
 260         return ERR_PTR(-EOPNOTSUPP);
 261 }
 262
 263 static struct nft_expr_type nft_hash_type __read_mostly = {
 264         .name           = "hash",
 265         .select_ops     = nft_hash_select_ops,
 266         .policy         = nft_hash_policy,
 267         .maxattr        = NFTA_HASH_MAX,
 268         .owner          = THIS_MODULE,
 269 };
 270
 271 static int __init nft_hash_module_init(void)
 272 {
 273         return nft_register_expr(&nft_hash_type);
 274 }
 275
 276 static void __exit nft_hash_module_exit(void)
 277 {
 278         nft_unregister_expr(&nft_hash_type);
 279 }
 280
 281 module_init(nft_hash_module_init);
 282 module_exit(nft_hash_module_exit);
 283
 284 MODULE_LICENSE("GPL");
 285 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
 286 MODULE_ALIAS_NFT_EXPR("hash");
 287 MODULE_DESCRIPTION("Netfilter nftables hash module");