![Laura Garcia Liebana](/assets/img/avatar_default.png)
The overflow validation in the init() function establishes that the
maximum value that the hash could reach is less than U32_MAX, which is
likely to be true.
The fix detects the overflow when the maximum hash value is less than
the offset itself.
Fixes: 70ca767ea1
("netfilter: nft_hash: Add hash offset value")
Reported-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
146 lines
3.8 KiB
C
146 lines
3.8 KiB
C
/*
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* Copyright (c) 2016 Laura Garcia <nevola@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/netlink.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables_core.h>
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#include <linux/jhash.h>
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struct nft_hash {
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enum nft_registers sreg:8;
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enum nft_registers dreg:8;
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u8 len;
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u32 modulus;
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u32 seed;
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u32 offset;
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};
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static void nft_hash_eval(const struct nft_expr *expr,
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struct nft_regs *regs,
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const struct nft_pktinfo *pkt)
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{
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struct nft_hash *priv = nft_expr_priv(expr);
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const void *data = ®s->data[priv->sreg];
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u32 h;
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h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus);
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regs->data[priv->dreg] = h + priv->offset;
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}
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static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
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[NFTA_HASH_SREG] = { .type = NLA_U32 },
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[NFTA_HASH_DREG] = { .type = NLA_U32 },
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[NFTA_HASH_LEN] = { .type = NLA_U32 },
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[NFTA_HASH_MODULUS] = { .type = NLA_U32 },
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[NFTA_HASH_SEED] = { .type = NLA_U32 },
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};
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static int nft_hash_init(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nlattr * const tb[])
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{
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struct nft_hash *priv = nft_expr_priv(expr);
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u32 len;
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if (!tb[NFTA_HASH_SREG] ||
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!tb[NFTA_HASH_DREG] ||
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!tb[NFTA_HASH_LEN] ||
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!tb[NFTA_HASH_SEED] ||
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!tb[NFTA_HASH_MODULUS])
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return -EINVAL;
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if (tb[NFTA_HASH_OFFSET])
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priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
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priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
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priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
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len = ntohl(nla_get_be32(tb[NFTA_HASH_LEN]));
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if (len == 0 || len > U8_MAX)
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return -ERANGE;
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priv->len = len;
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priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
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if (priv->modulus <= 1)
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return -ERANGE;
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if (priv->offset + priv->modulus - 1 < priv->offset)
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return -EOVERFLOW;
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priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
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return nft_validate_register_load(priv->sreg, len) &&
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nft_validate_register_store(ctx, priv->dreg, NULL,
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NFT_DATA_VALUE, sizeof(u32));
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}
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static int nft_hash_dump(struct sk_buff *skb,
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const struct nft_expr *expr)
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{
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const struct nft_hash *priv = nft_expr_priv(expr);
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if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
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goto nla_put_failure;
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if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_HASH_LEN, htonl(priv->len)))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus)))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
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goto nla_put_failure;
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if (priv->offset != 0)
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if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
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goto nla_put_failure;
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return 0;
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nla_put_failure:
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return -1;
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}
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static struct nft_expr_type nft_hash_type;
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static const struct nft_expr_ops nft_hash_ops = {
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.type = &nft_hash_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_hash)),
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.eval = nft_hash_eval,
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.init = nft_hash_init,
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.dump = nft_hash_dump,
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};
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static struct nft_expr_type nft_hash_type __read_mostly = {
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.name = "hash",
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.ops = &nft_hash_ops,
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.policy = nft_hash_policy,
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.maxattr = NFTA_HASH_MAX,
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.owner = THIS_MODULE,
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};
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static int __init nft_hash_module_init(void)
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{
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return nft_register_expr(&nft_hash_type);
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}
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static void __exit nft_hash_module_exit(void)
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{
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nft_unregister_expr(&nft_hash_type);
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}
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module_init(nft_hash_module_init);
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module_exit(nft_hash_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
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MODULE_ALIAS_NFT_EXPR("hash");
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