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 enum nft_registers sreg:8; 18 enum nft_registers dreg:8; 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 enum nft_registers dreg:8; 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 priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]); 87 priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]); 88 89 err = nft_parse_u32_check(tb[NFTA_HASH_LEN], U8_MAX, &len); 90 if (err < 0) 91 return err; 92 if (len == 0) 93 return -ERANGE; 94 95 priv->len = len; 96 97 priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS])); 98 if (priv->modulus < 1) 99 return -ERANGE; 100 101 if (priv->offset + priv->modulus - 1 < priv->offset) 102 return -EOVERFLOW; 103 104 if (tb[NFTA_HASH_SEED]) { 105 priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED])); 106 } else { 107 priv->autogen_seed = true; 108 get_random_bytes(&priv->seed, sizeof(priv->seed)); 109 } 110 111 return nft_validate_register_load(priv->sreg, len) && 112 nft_validate_register_store(ctx, priv->dreg, NULL, 113 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->dreg = nft_parse_register(tb[NFTA_HASH_DREG]); 130 131 priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS])); 132 if (priv->modulus < 1) 133 return -ERANGE; 134 135 if (priv->offset + priv->modulus - 1 < priv->offset) 136 return -EOVERFLOW; 137 138 return nft_validate_register_store(ctx, priv->dreg, NULL, 139 NFT_DATA_VALUE, sizeof(u32)); 140 } 141 142 static int nft_jhash_dump(struct sk_buff *skb, 143 const struct nft_expr *expr) 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 int nft_symhash_dump(struct sk_buff *skb, 170 const struct nft_expr *expr) 171 { 172 const struct nft_symhash *priv = nft_expr_priv(expr); 173 174 if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg)) 175 goto nla_put_failure; 176 if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus))) 177 goto nla_put_failure; 178 if (priv->offset != 0) 179 if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset))) 180 goto nla_put_failure; 181 if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM))) 182 goto nla_put_failure; 183 return 0; 184 185 nla_put_failure: 186 return -1; 187 } 188 189 static struct nft_expr_type nft_hash_type; 190 static const struct nft_expr_ops nft_jhash_ops = { 191 .type = &nft_hash_type, 192 .size = NFT_EXPR_SIZE(sizeof(struct nft_jhash)), 193 .eval = nft_jhash_eval, 194 .init = nft_jhash_init, 195 .dump = nft_jhash_dump, 196 }; 197 198 static const struct nft_expr_ops nft_symhash_ops = { 199 .type = &nft_hash_type, 200 .size = NFT_EXPR_SIZE(sizeof(struct nft_symhash)), 201 .eval = nft_symhash_eval, 202 .init = nft_symhash_init, 203 .dump = nft_symhash_dump, 204 }; 205 206 static const struct nft_expr_ops * 207 nft_hash_select_ops(const struct nft_ctx *ctx, 208 const struct nlattr * const tb[]) 209 { 210 u32 type; 211 212 if (!tb[NFTA_HASH_TYPE]) 213 return &nft_jhash_ops; 214 215 type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE])); 216 switch (type) { 217 case NFT_HASH_SYM: 218 return &nft_symhash_ops; 219 case NFT_HASH_JENKINS: 220 return &nft_jhash_ops; 221 default: 222 break; 223 } 224 return ERR_PTR(-EOPNOTSUPP); 225 } 226 227 static struct nft_expr_type nft_hash_type __read_mostly = { 228 .name = "hash", 229 .select_ops = nft_hash_select_ops, 230 .policy = nft_hash_policy, 231 .maxattr = NFTA_HASH_MAX, 232 .owner = THIS_MODULE, 233 }; 234 235 static int __init nft_hash_module_init(void) 236 { 237 return nft_register_expr(&nft_hash_type); 238 } 239 240 static void __exit nft_hash_module_exit(void) 241 { 242 nft_unregister_expr(&nft_hash_type); 243 } 244 245 module_init(nft_hash_module_init); 246 module_exit(nft_hash_module_exit); 247 248 MODULE_LICENSE("GPL"); 249 MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>"); 250 MODULE_ALIAS_NFT_EXPR("hash"); 251 MODULE_DESCRIPTION("Netfilter nftables hash module"); 252