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(skb), priv->modulus);
  55
  56         regs->data[priv->dreg] = h + priv->offset;
  57 }
  58
  59 static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
  60         [NFTA_HASH_SREG]        = { .type = NLA_U32 },
  61         [NFTA_HASH_DREG]        = { .type = NLA_U32 },
  62         [NFTA_HASH_LEN]         = { .type = NLA_U32 },
  63         [NFTA_HASH_MODULUS]     = { .type = NLA_U32 },
  64         [NFTA_HASH_SEED]        = { .type = NLA_U32 },
  65         [NFTA_HASH_OFFSET]      = { .type = NLA_U32 },
  66         [NFTA_HASH_TYPE]        = { .type = NLA_U32 },
  67 };
  68
  69 static int nft_jhash_init(const struct nft_ctx *ctx,
  70                           const struct nft_expr *expr,
  71                           const struct nlattr * const tb[])
  72 {
  73         struct nft_jhash *priv = nft_expr_priv(expr);
  74         u32 len;
  75         int err;
  76
  77         if (!tb[NFTA_HASH_SREG] ||
  78             !tb[NFTA_HASH_DREG] ||
  79             !tb[NFTA_HASH_LEN]  ||
  80             !tb[NFTA_HASH_MODULUS])
  81                 return -EINVAL;
  82
  83         if (tb[NFTA_HASH_OFFSET])
  84                 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
  85
  86         err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len);
  87         if (err < 0)
  88                 return err;
  89         if (len == 0)
  90                 return -ERANGE;
  91
  92         priv->len = len;
  93
  94         err = nft_parse_register_load(tb[NFTA_HASH_SREG], &priv->sreg, len);
  95         if (err < 0)
  96                 return err;
  97
  98         priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
  99         if (priv->modulus < 1)
 100                 return -ERANGE;
 101
 102         if (priv->offset + priv->modulus - 1 < priv->offset)
 103                 return -EOVERFLOW;
 104
 105         if (tb[NFTA_HASH_SEED]) {
 106                 priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
 107         } else {
 108                 priv->autogen_seed = true;
 109                 get_random_bytes(&priv->seed, sizeof(priv->seed));
 110         }
 111
 112         return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG], &priv->dreg,
 113                                         NULL, NFT_DATA_VALUE, sizeof(u32));
 114 }
 115
 116 static int nft_symhash_init(const struct nft_ctx *ctx,
 117                             const struct nft_expr *expr,
 118                             const struct nlattr * const tb[])
 119 {
 120         struct nft_symhash *priv = nft_expr_priv(expr);
 121
 122         if (!tb[NFTA_HASH_DREG]    ||
 123             !tb[NFTA_HASH_MODULUS])
 124                 return -EINVAL;
 125
 126         if (tb[NFTA_HASH_OFFSET])
 127                 priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
 128
 129         priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
 130         if (priv->modulus < 1)
 131                 return -ERANGE;
 132
 133         if (priv->offset + priv->modulus - 1 < priv->offset)
 134                 return -EOVERFLOW;
 135
 136         return nft_parse_register_store(ctx, tb[NFTA_HASH_DREG],
 137                                         &priv->dreg, NULL, NFT_DATA_VALUE,
 138                                         sizeof(u32));
 139 }
 140
 141 static int nft_jhash_dump(struct sk_buff *skb,
 142                           const struct nft_expr *expr)
 143 {
 144         const struct nft_jhash *priv = nft_expr_priv(expr);
 145
 146         if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
 147                 goto nla_put_failure;
 148         if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
 149                 goto nla_put_failure;
 150         if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
 151                 goto nla_put_failure;
 152         if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
 153                 goto nla_put_failure;
 154         if (!priv->autogen_seed &&
 155             nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
 156                 goto nla_put_failure;
 157         if (priv->offset != 0)
 158                 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
 159                         goto nla_put_failure;
 160         if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS)))
 161                 goto nla_put_failure;
 162         return 0;
 163
 164 nla_put_failure:
 165         return -1;
 166 }
 167
 168 static int nft_symhash_dump(struct sk_buff *skb,
 169                             const struct nft_expr *expr)
 170 {
 171         const struct nft_symhash *priv = nft_expr_priv(expr);
 172
 173         if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
 174                 goto nla_put_failure;
 175         if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
 176                 goto nla_put_failure;
 177         if (priv->offset != 0)
 178                 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
 179                         goto nla_put_failure;
 180         if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM)))
 181                 goto nla_put_failure;
 182         return 0;
 183
 184 nla_put_failure:
 185         return -1;
 186 }
 187
 188 static struct nft_expr_type nft_hash_type;
 189 static const struct nft_expr_ops nft_jhash_ops = {
 190         .type           = &nft_hash_type,
 191         .size           = NFT_EXPR_SIZE(sizeof(struct nft_jhash)),
 192         .eval           = nft_jhash_eval,
 193         .init           = nft_jhash_init,
 194         .dump           = nft_jhash_dump,
 195 };
 196
 197 static const struct nft_expr_ops nft_symhash_ops = {
 198         .type           = &nft_hash_type,
 199         .size           = NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
 200         .eval           = nft_symhash_eval,
 201         .init           = nft_symhash_init,
 202         .dump           = nft_symhash_dump,
 203 };
 204
 205 static const struct nft_expr_ops *
 206 nft_hash_select_ops(const struct nft_ctx *ctx,
 207                     const struct nlattr * const tb[])
 208 {
 209         u32 type;
 210
 211         if (!tb[NFTA_HASH_TYPE])
 212                 return &nft_jhash_ops;
 213
 214         type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));
 215         switch (type) {
 216         case NFT_HASH_SYM:
 217                 return &nft_symhash_ops;
 218         case NFT_HASH_JENKINS:
 219                 return &nft_jhash_ops;
 220         default:
 221                 break;
 222         }
 223         return ERR_PTR(-EOPNOTSUPP);
 224 }
 225
 226 static struct nft_expr_type nft_hash_type __read_mostly = {
 227         .name           = "hash",
 228         .select_ops     = nft_hash_select_ops,
 229         .policy         = nft_hash_policy,
 230         .maxattr        = NFTA_HASH_MAX,
 231         .owner          = THIS_MODULE,
 232 };
 233
 234 static int __init nft_hash_module_init(void)
 235 {
 236         return nft_register_expr(&nft_hash_type);
 237 }
 238
 239 static void __exit nft_hash_module_exit(void)
 240 {
 241         nft_unregister_expr(&nft_hash_type);
 242 }
 243
 244 module_init(nft_hash_module_init);
 245 module_exit(nft_hash_module_exit);
 246
 247 MODULE_LICENSE("GPL");
 248 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
 249 MODULE_ALIAS_NFT_EXPR("hash");
 250 MODULE_DESCRIPTION("Netfilter nftables hash module");