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 = ®s->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"); 251