net/netfilter/nft_hash.c

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