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netfilter: nf_tables: add xfrm expression 

supports fetching saddr/daddr of tunnel mode states, request id and spi.
If direction is 'in', use inbound skb secpath, else dst->xfrm.

Joint work with Máté Eckl.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2018-09-03 18:09:40 +02:00 committed by Pablo Neira Ayuso
parent 2953d80ff0
commit 6c47260250
4 changed files with 330 additions and 0 deletions
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29
include/uapi/linux/netfilter/nf_tables.h
View File

@ -1514,6 +1514,35 @@ enum nft_devices_attributes {
};
#define NFTA_DEVICE_MAX (__NFTA_DEVICE_MAX - 1)
/*
* enum nft_xfrm_attributes - nf_tables xfrm expr netlink attributes
*
* @NFTA_XFRM_DREG: destination register (NLA_U32)
* @NFTA_XFRM_KEY: enum nft_xfrm_keys (NLA_U32)
* @NFTA_XFRM_DIR: direction (NLA_U8)
* @NFTA_XFRM_SPNUM: index in secpath array (NLA_U32)
*/
enum nft_xfrm_attributes {
NFTA_XFRM_UNSPEC,
NFTA_XFRM_DREG,
NFTA_XFRM_KEY,
NFTA_XFRM_DIR,
NFTA_XFRM_SPNUM,
__NFTA_XFRM_MAX
};
#define NFTA_XFRM_MAX (__NFTA_XFRM_MAX - 1)
enum nft_xfrm_keys {
NFT_XFRM_KEY_UNSPEC,
NFT_XFRM_KEY_DADDR_IP4,
NFT_XFRM_KEY_DADDR_IP6,
NFT_XFRM_KEY_SADDR_IP4,
NFT_XFRM_KEY_SADDR_IP6,
NFT_XFRM_KEY_REQID,
NFT_XFRM_KEY_SPI,
__NFT_XFRM_KEY_MAX,
};
#define NFT_XFRM_KEY_MAX (__NFT_XFRM_KEY_MAX - 1)
/**
* enum nft_trace_attributes - nf_tables trace netlink attributes

7
net/netfilter/Kconfig
View File

@ -625,6 +625,13 @@ config NFT_FIB_INET
The lookup will be delegated to the IPv4 or IPv6 FIB depending
on the protocol of the packet.
config NFT_XFRM
tristate "Netfilter nf_tables xfrm/IPSec security association matching"
depends on XFRM
help
This option adds an expression that you can use to extract properties
of a packets security association.
config NFT_SOCKET
tristate "Netfilter nf_tables socket match support"
depends on IPV6 || IPV6=n

1
net/netfilter/Makefile
View File

@ -113,6 +113,7 @@ obj-$(CONFIG_NFT_FIB_NETDEV) += nft_fib_netdev.o
obj-$(CONFIG_NFT_SOCKET) += nft_socket.o
obj-$(CONFIG_NFT_OSF) += nft_osf.o
obj-$(CONFIG_NFT_TPROXY) += nft_tproxy.o
obj-$(CONFIG_NFT_XFRM) += nft_xfrm.o
# nf_tables netdev
obj-$(CONFIG_NFT_DUP_NETDEV) += nft_dup_netdev.o

293
net/netfilter/nft_xfrm.c Normal file
View File

@ -0,0 +1,293 @@
/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Generic part shared by ipv4 and ipv6 backends.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
#include <linux/in.h>
#include <net/xfrm.h>
static const struct nla_policy nft_xfrm_policy[NFTA_XFRM_MAX + 1] = {
[NFTA_XFRM_KEY] = { .type = NLA_U32 },
[NFTA_XFRM_DIR] = { .type = NLA_U8 },
[NFTA_XFRM_SPNUM] = { .type = NLA_U32 },
[NFTA_XFRM_DREG] = { .type = NLA_U32 },
};
struct nft_xfrm {
enum nft_xfrm_keys key:8;
enum nft_registers dreg:8;
u8 dir;
u8 spnum;
};
static int nft_xfrm_get_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_xfrm *priv = nft_expr_priv(expr);
unsigned int len = 0;
u32 spnum = 0;
u8 dir;
if (!tb[NFTA_XFRM_KEY] || !tb[NFTA_XFRM_DIR] || !tb[NFTA_XFRM_DREG])
return -EINVAL;
switch (ctx->family) {
case NFPROTO_IPV4:
case NFPROTO_IPV6:
case NFPROTO_INET:
break;
default:
return -EOPNOTSUPP;
}
priv->key = ntohl(nla_get_u32(tb[NFTA_XFRM_KEY]));
switch (priv->key) {
case NFT_XFRM_KEY_REQID:
case NFT_XFRM_KEY_SPI:
len = sizeof(u32);
break;
case NFT_XFRM_KEY_DADDR_IP4:
case NFT_XFRM_KEY_SADDR_IP4:
len = sizeof(struct in_addr);
break;
case NFT_XFRM_KEY_DADDR_IP6:
case NFT_XFRM_KEY_SADDR_IP6:
len = sizeof(struct in6_addr);
break;
default:
return -EINVAL;
}
dir = nla_get_u8(tb[NFTA_XFRM_DIR]);
switch (dir) {
case XFRM_POLICY_IN:
case XFRM_POLICY_OUT:
priv->dir = dir;
break;
default:
return -EINVAL;
}
if (tb[NFTA_XFRM_SPNUM])
spnum = ntohl(nla_get_be32(tb[NFTA_XFRM_SPNUM]));
if (spnum >= XFRM_MAX_DEPTH)
return -ERANGE;
priv->spnum = spnum;
priv->dreg = nft_parse_register(tb[NFTA_XFRM_DREG]);
return nft_validate_register_store(ctx, priv->dreg, NULL,
NFT_DATA_VALUE, len);
}
/* Return true if key asks for daddr/saddr and current
* state does have a valid address (BEET, TUNNEL).
*/
static bool xfrm_state_addr_ok(enum nft_xfrm_keys k, u8 family, u8 mode)
{
switch (k) {
case NFT_XFRM_KEY_DADDR_IP4:
case NFT_XFRM_KEY_SADDR_IP4:
if (family == NFPROTO_IPV4)
break;
return false;
case NFT_XFRM_KEY_DADDR_IP6:
case NFT_XFRM_KEY_SADDR_IP6:
if (family == NFPROTO_IPV6)
break;
return false;
default:
return true;
}
return mode == XFRM_MODE_BEET || mode == XFRM_MODE_TUNNEL;
}
static void nft_xfrm_state_get_key(const struct nft_xfrm *priv,
struct nft_regs *regs,
const struct xfrm_state *state,
u8 family)
{
u32 *dest = &regs->data[priv->dreg];
if (!xfrm_state_addr_ok(priv->key, family, state->props.mode)) {
regs->verdict.code = NFT_BREAK;
return;
}
switch (priv->key) {
case NFT_XFRM_KEY_UNSPEC:
case __NFT_XFRM_KEY_MAX:
WARN_ON_ONCE(1);
break;
case NFT_XFRM_KEY_DADDR_IP4:
*dest = state->id.daddr.a4;
return;
case NFT_XFRM_KEY_DADDR_IP6:
memcpy(dest, &state->id.daddr.in6, sizeof(struct in6_addr));
return;
case NFT_XFRM_KEY_SADDR_IP4:
*dest = state->props.saddr.a4;
return;
case NFT_XFRM_KEY_SADDR_IP6:
memcpy(dest, &state->props.saddr.in6, sizeof(struct in6_addr));
return;
case NFT_XFRM_KEY_REQID:
*dest = state->props.reqid;
return;
case NFT_XFRM_KEY_SPI:
*dest = state->id.spi;
return;
}
regs->verdict.code = NFT_BREAK;
}
static void nft_xfrm_get_eval_in(const struct nft_xfrm *priv,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct sec_path *sp = pkt->skb->sp;
const struct xfrm_state *state;
if (sp == NULL || sp->len <= priv->spnum) {
regs->verdict.code = NFT_BREAK;
return;
}
state = sp->xvec[priv->spnum];
nft_xfrm_state_get_key(priv, regs, state, nft_pf(pkt));
}
static void nft_xfrm_get_eval_out(const struct nft_xfrm *priv,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct dst_entry *dst = skb_dst(pkt->skb);
int i;
for (i = 0; dst && dst->xfrm;
dst = ((const struct xfrm_dst *)dst)->child, i++) {
if (i < priv->spnum)
continue;
nft_xfrm_state_get_key(priv, regs, dst->xfrm, nft_pf(pkt));
return;
}
regs->verdict.code = NFT_BREAK;
}
static void nft_xfrm_get_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_xfrm *priv = nft_expr_priv(expr);
switch (priv->dir) {
case XFRM_POLICY_IN:
nft_xfrm_get_eval_in(priv, regs, pkt);
break;
case XFRM_POLICY_OUT:
nft_xfrm_get_eval_out(priv, regs, pkt);
break;
default:
WARN_ON_ONCE(1);
regs->verdict.code = NFT_BREAK;
break;
}
}
static int nft_xfrm_get_dump(struct sk_buff *skb,
const struct nft_expr *expr)
{
const struct nft_xfrm *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_XFRM_DREG, priv->dreg))
return -1;
if (nla_put_be32(skb, NFTA_XFRM_KEY, htonl(priv->key)))
return -1;
if (nla_put_u8(skb, NFTA_XFRM_DIR, priv->dir))
return -1;
if (nla_put_be32(skb, NFTA_XFRM_SPNUM, htonl(priv->spnum)))
return -1;
return 0;
}
static int nft_xfrm_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
const struct nft_data **data)
{
const struct nft_xfrm *priv = nft_expr_priv(expr);
unsigned int hooks;
switch (priv->dir) {
case XFRM_POLICY_IN:
hooks = (1 << NF_INET_FORWARD) |
(1 << NF_INET_LOCAL_IN) |
(1 << NF_INET_PRE_ROUTING);
break;
case XFRM_POLICY_OUT:
hooks = (1 << NF_INET_FORWARD) |
(1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_POST_ROUTING);
break;
default:
WARN_ON_ONCE(1);
return -EINVAL;
}
return nft_chain_validate_hooks(ctx->chain, hooks);
}
static struct nft_expr_type nft_xfrm_type;
static const struct nft_expr_ops nft_xfrm_get_ops = {
.type = &nft_xfrm_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_xfrm)),
.eval = nft_xfrm_get_eval,
.init = nft_xfrm_get_init,
.dump = nft_xfrm_get_dump,
.validate = nft_xfrm_validate,
};
static struct nft_expr_type nft_xfrm_type __read_mostly = {
.name = "xfrm",
.ops = &nft_xfrm_get_ops,
.policy = nft_xfrm_policy,
.maxattr = NFTA_XFRM_MAX,
.owner = THIS_MODULE,
};
static int __init nft_xfrm_module_init(void)
{
return nft_register_expr(&nft_xfrm_type);
}
static void __exit nft_xfrm_module_exit(void)
{
nft_unregister_expr(&nft_xfrm_type);
}
module_init(nft_xfrm_module_init);
module_exit(nft_xfrm_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("nf_tables: xfrm/IPSec matching");
MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
MODULE_AUTHOR("Máté Eckl <ecklm94@gmail.com>");
MODULE_ALIAS_NFT_EXPR("xfrm");