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alistair23-linux/net/netfilter/nft_nat.c
Pablo Neira Ayuso 75e8d06d43 netfilter: nf_tables: validate hooks in NAT expressions 
The user can crash the kernel if it uses any of the existing NAT
expressions from the wrong hook, so add some code to validate this
when loading the rule.

This patch introduces nft_chain_validate_hooks() which is based on
an existing function in the bridge version of the reject expression.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2015-01-19 14:52:39 +01:00

283 lines
7.1 KiB
C
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/*
* Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
* Copyright (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
* Copyright (c) 2012 Intel Corporation
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/string.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_nat_l3proto.h>
#include <net/ip.h>
struct nft_nat {
enum nft_registers sreg_addr_min:8;
enum nft_registers sreg_addr_max:8;
enum nft_registers sreg_proto_min:8;
enum nft_registers sreg_proto_max:8;
enum nf_nat_manip_type type:8;
u8 family;
u16 flags;
};
static void nft_nat_eval(const struct nft_expr *expr,
struct nft_data data[NFT_REG_MAX + 1],
const struct nft_pktinfo *pkt)
{
const struct nft_nat *priv = nft_expr_priv(expr);
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(pkt->skb, &ctinfo);
struct nf_nat_range range;
memset(&range, 0, sizeof(range));
if (priv->sreg_addr_min) {
if (priv->family == AF_INET) {
range.min_addr.ip = (__force __be32)
data[priv->sreg_addr_min].data[0];
range.max_addr.ip = (__force __be32)
data[priv->sreg_addr_max].data[0];
} else {
memcpy(range.min_addr.ip6,
data[priv->sreg_addr_min].data,
sizeof(struct nft_data));
memcpy(range.max_addr.ip6,
data[priv->sreg_addr_max].data,
sizeof(struct nft_data));
}
range.flags |= NF_NAT_RANGE_MAP_IPS;
}
if (priv->sreg_proto_min) {
range.min_proto.all =
*(__be16 *)&data[priv->sreg_proto_min].data[0];
range.max_proto.all =
*(__be16 *)&data[priv->sreg_proto_max].data[0];
range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
}
range.flags |= priv->flags;
data[NFT_REG_VERDICT].verdict =
nf_nat_setup_info(ct, &range, priv->type);
}
static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
[NFTA_NAT_TYPE] = { .type = NLA_U32 },
[NFTA_NAT_FAMILY] = { .type = NLA_U32 },
[NFTA_NAT_REG_ADDR_MIN] = { .type = NLA_U32 },
[NFTA_NAT_REG_ADDR_MAX] = { .type = NLA_U32 },
[NFTA_NAT_REG_PROTO_MIN] = { .type = NLA_U32 },
[NFTA_NAT_REG_PROTO_MAX] = { .type = NLA_U32 },
[NFTA_NAT_FLAGS] = { .type = NLA_U32 },
};
static int nft_nat_validate(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nft_data **data)
{
struct nft_nat *priv = nft_expr_priv(expr);
int err;
err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
if (err < 0)
return err;
switch (priv->type) {
case NFT_NAT_SNAT:
err = nft_chain_validate_hooks(ctx->chain,
(1 << NF_INET_POST_ROUTING) |
(1 << NF_INET_LOCAL_IN));
break;
case NFT_NAT_DNAT:
err = nft_chain_validate_hooks(ctx->chain,
(1 << NF_INET_PRE_ROUTING) |
(1 << NF_INET_LOCAL_OUT));
break;
}
return err;
}
static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_nat *priv = nft_expr_priv(expr);
u32 family;
int err;
if (tb[NFTA_NAT_TYPE] == NULL ||
(tb[NFTA_NAT_REG_ADDR_MIN] == NULL &&
tb[NFTA_NAT_REG_PROTO_MIN] == NULL))
return -EINVAL;
switch (ntohl(nla_get_be32(tb[NFTA_NAT_TYPE]))) {
case NFT_NAT_SNAT:
priv->type = NF_NAT_MANIP_SRC;
break;
case NFT_NAT_DNAT:
priv->type = NF_NAT_MANIP_DST;
break;
default:
return -EINVAL;
}
err = nft_nat_validate(ctx, expr, NULL);
if (err < 0)
return err;
if (tb[NFTA_NAT_FAMILY] == NULL)
return -EINVAL;
family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
if (family != AF_INET && family != AF_INET6)
return -EAFNOSUPPORT;
if (family != ctx->afi->family)
return -EOPNOTSUPP;
priv->family = family;
if (tb[NFTA_NAT_REG_ADDR_MIN]) {
priv->sreg_addr_min =
ntohl(nla_get_be32(tb[NFTA_NAT_REG_ADDR_MIN]));
err = nft_validate_input_register(priv->sreg_addr_min);
if (err < 0)
return err;
if (tb[NFTA_NAT_REG_ADDR_MAX]) {
priv->sreg_addr_max =
ntohl(nla_get_be32(tb[NFTA_NAT_REG_ADDR_MAX]));
err = nft_validate_input_register(priv->sreg_addr_max);
if (err < 0)
return err;
} else {
priv->sreg_addr_max = priv->sreg_addr_min;
}
}
if (tb[NFTA_NAT_REG_PROTO_MIN]) {
priv->sreg_proto_min =
ntohl(nla_get_be32(tb[NFTA_NAT_REG_PROTO_MIN]));
err = nft_validate_input_register(priv->sreg_proto_min);
if (err < 0)
return err;
if (tb[NFTA_NAT_REG_PROTO_MAX]) {
priv->sreg_proto_max =
ntohl(nla_get_be32(tb[NFTA_NAT_REG_PROTO_MAX]));
err = nft_validate_input_register(priv->sreg_proto_max);
if (err < 0)
return err;
} else {
priv->sreg_proto_max = priv->sreg_proto_min;
}
}
if (tb[NFTA_NAT_FLAGS]) {
priv->flags = ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
if (priv->flags & ~NF_NAT_RANGE_MASK)
return -EINVAL;
}
return 0;
}
static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_nat *priv = nft_expr_priv(expr);
switch (priv->type) {
case NF_NAT_MANIP_SRC:
if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_SNAT)))
goto nla_put_failure;
break;
case NF_NAT_MANIP_DST:
if (nla_put_be32(skb, NFTA_NAT_TYPE, htonl(NFT_NAT_DNAT)))
goto nla_put_failure;
break;
}
if (nla_put_be32(skb, NFTA_NAT_FAMILY, htonl(priv->family)))
goto nla_put_failure;
if (priv->sreg_addr_min) {
if (nla_put_be32(skb, NFTA_NAT_REG_ADDR_MIN,
htonl(priv->sreg_addr_min)) ||
nla_put_be32(skb, NFTA_NAT_REG_ADDR_MAX,
htonl(priv->sreg_addr_max)))
goto nla_put_failure;
}
if (priv->sreg_proto_min) {
if (nla_put_be32(skb, NFTA_NAT_REG_PROTO_MIN,
htonl(priv->sreg_proto_min)) ||
nla_put_be32(skb, NFTA_NAT_REG_PROTO_MAX,
htonl(priv->sreg_proto_max)))
goto nla_put_failure;
}
if (priv->flags != 0) {
if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
goto nla_put_failure;
}
return 0;
nla_put_failure:
return -1;
}
static struct nft_expr_type nft_nat_type;
static const struct nft_expr_ops nft_nat_ops = {
.type = &nft_nat_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
.eval = nft_nat_eval,
.init = nft_nat_init,
.dump = nft_nat_dump,
.validate = nft_nat_validate,
};
static struct nft_expr_type nft_nat_type __read_mostly = {
.name = "nat",
.ops = &nft_nat_ops,
.policy = nft_nat_policy,
.maxattr = NFTA_NAT_MAX,
.owner = THIS_MODULE,
};
static int __init nft_nat_module_init(void)
{
return nft_register_expr(&nft_nat_type);
}
static void __exit nft_nat_module_exit(void)
{
nft_unregister_expr(&nft_nat_type);
}
module_init(nft_nat_module_init);
module_exit(nft_nat_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
MODULE_ALIAS_NFT_EXPR("nat");
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