540436c80e
In nft's nft_exthdr_eval() routine we process IPv6 extension header
through invoking ipv6_find_hdr(), but we call it with an uninitialized
offset variable that contains some stack value. In ipv6_find_hdr()
we then test if the value of offset != 0 and call skb_header_pointer()
on that offset in order to map struct ipv6hdr into it. Fix it up by
initializing offset to 0 as it was probably intended to be.
Fixes: 96518518cc
("netfilter: add nftables")
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
134 lines
3.5 KiB
C
134 lines
3.5 KiB
C
/*
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* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
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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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* Development of this code funded by Astaro AG (http://www.astaro.com/)
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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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// FIXME:
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#include <net/ipv6.h>
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struct nft_exthdr {
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u8 type;
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u8 offset;
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u8 len;
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enum nft_registers dreg:8;
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};
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static void nft_exthdr_eval(const struct nft_expr *expr,
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struct nft_data data[NFT_REG_MAX + 1],
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const struct nft_pktinfo *pkt)
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{
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struct nft_exthdr *priv = nft_expr_priv(expr);
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struct nft_data *dest = &data[priv->dreg];
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unsigned int offset = 0;
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int err;
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err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
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if (err < 0)
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goto err;
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offset += priv->offset;
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if (skb_copy_bits(pkt->skb, offset, dest->data, priv->len) < 0)
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goto err;
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return;
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err:
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data[NFT_REG_VERDICT].verdict = NFT_BREAK;
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}
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static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
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[NFTA_EXTHDR_DREG] = { .type = NLA_U32 },
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[NFTA_EXTHDR_TYPE] = { .type = NLA_U8 },
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[NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 },
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[NFTA_EXTHDR_LEN] = { .type = NLA_U32 },
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};
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static int nft_exthdr_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_exthdr *priv = nft_expr_priv(expr);
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int err;
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if (tb[NFTA_EXTHDR_DREG] == NULL ||
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tb[NFTA_EXTHDR_TYPE] == NULL ||
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tb[NFTA_EXTHDR_OFFSET] == NULL ||
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tb[NFTA_EXTHDR_LEN] == NULL)
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return -EINVAL;
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priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
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priv->offset = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OFFSET]));
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priv->len = ntohl(nla_get_be32(tb[NFTA_EXTHDR_LEN]));
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if (priv->len == 0 ||
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priv->len > FIELD_SIZEOF(struct nft_data, data))
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return -EINVAL;
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priv->dreg = ntohl(nla_get_be32(tb[NFTA_EXTHDR_DREG]));
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err = nft_validate_output_register(priv->dreg);
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if (err < 0)
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return err;
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return nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE);
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}
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static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
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{
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const struct nft_exthdr *priv = nft_expr_priv(expr);
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if (nla_put_be32(skb, NFTA_EXTHDR_DREG, htonl(priv->dreg)))
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goto nla_put_failure;
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if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
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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_exthdr_type;
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static const struct nft_expr_ops nft_exthdr_ops = {
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.type = &nft_exthdr_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
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.eval = nft_exthdr_eval,
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.init = nft_exthdr_init,
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.dump = nft_exthdr_dump,
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};
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static struct nft_expr_type nft_exthdr_type __read_mostly = {
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.name = "exthdr",
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.ops = &nft_exthdr_ops,
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.policy = nft_exthdr_policy,
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.maxattr = NFTA_EXTHDR_MAX,
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.owner = THIS_MODULE,
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};
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static int __init nft_exthdr_module_init(void)
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{
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return nft_register_expr(&nft_exthdr_type);
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}
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static void __exit nft_exthdr_module_exit(void)
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{
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nft_unregister_expr(&nft_exthdr_type);
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}
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module_init(nft_exthdr_module_init);
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module_exit(nft_exthdr_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_ALIAS_NFT_EXPR("exthdr");
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