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/*
* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
*
* 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.
*
* Development of this code funded by Astaro AG (http://www.astaro.com/)
*/
#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.h>
#include <net/tcp.h>
struct nft_exthdr {
u8 type;
u8 offset;
u8 len;
u8 op;
enum nft_registers dreg:8;
u8 flags;
};
static unsigned int optlen(const u8 *opt, unsigned int offset)
{
/* Beware zero-length options: make finite progress */
if (opt[offset] <= TCPOPT_NOP || opt[offset + 1] == 0)
return 1;
else
return opt[offset + 1];
}
static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_exthdr *priv = nft_expr_priv(expr);
u32 *dest = ®s->data[priv->dreg];
unsigned int offset = 0;
int err;
err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
if (priv->flags & NFT_EXTHDR_F_PRESENT) {
*dest = (err >= 0);
return;
} else if (err < 0) {
goto err;
}
offset += priv->offset;
dest[priv->len / NFT_REG32_SIZE] = 0;
if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
goto err;
return;
err:
regs->verdict.code = NFT_BREAK;
}
static void nft_exthdr_tcp_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
struct nft_exthdr *priv = nft_expr_priv(expr);
unsigned int i, optl, tcphdr_len, offset;
u32 *dest = ®s->data[priv->dreg];
struct tcphdr *tcph;
u8 *opt;
if (!pkt->tprot_set || pkt->tprot != IPPROTO_TCP)
goto err;
tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, sizeof(*tcph), buff);
if (!tcph)
goto err;
tcphdr_len = __tcp_hdrlen(tcph);
if (tcphdr_len < sizeof(*tcph))
goto err;
tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, tcphdr_len, buff);
if (!tcph)
goto err;
opt = (u8 *)tcph;
for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
optl = optlen(opt, i);
if (priv->type != opt[i])
continue;
if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
goto err;
offset = i + priv->offset;
if (priv->flags & NFT_EXTHDR_F_PRESENT) {
*dest = 1;
} else {
dest[priv->len / NFT_REG32_SIZE] = 0;
memcpy(dest, opt + offset, priv->len);
}
return;
}
err:
if (priv->flags & NFT_EXTHDR_F_PRESENT)
*dest = 0;
else
regs->verdict.code = NFT_BREAK;
}
static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
[NFTA_EXTHDR_DREG] = { .type = NLA_U32 },
[NFTA_EXTHDR_TYPE] = { .type = NLA_U8 },
[NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 },
[NFTA_EXTHDR_LEN] = { .type = NLA_U32 },
[NFTA_EXTHDR_FLAGS] = { .type = NLA_U32 },
};
static int nft_exthdr_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_exthdr *priv = nft_expr_priv(expr);
u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
int err;
if (!tb[NFTA_EXTHDR_DREG] ||
!tb[NFTA_EXTHDR_TYPE] ||
!tb[NFTA_EXTHDR_OFFSET] ||
!tb[NFTA_EXTHDR_LEN])
return -EINVAL;
err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
if (err < 0)
return err;
err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
if (err < 0)
return err;
if (tb[NFTA_EXTHDR_FLAGS]) {
err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags);
if (err < 0)
return err;
if (flags & ~NFT_EXTHDR_F_PRESENT)
return -EINVAL;
}
if (tb[NFTA_EXTHDR_OP]) {
err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
if (err < 0)
return err;
}
priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
priv->offset = offset;
priv->len = len;
priv->dreg = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
priv->flags = flags;
priv->op = op;
return nft_validate_register_store(ctx, priv->dreg, NULL,
NFT_DATA_VALUE, priv->len);
}
static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_exthdr *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
goto nla_put_failure;
if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags)))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op)))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static struct nft_expr_type nft_exthdr_type;
static const struct nft_expr_ops nft_exthdr_ipv6_ops = {
.type = &nft_exthdr_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
.eval = nft_exthdr_ipv6_eval,
.init = nft_exthdr_init,
.dump = nft_exthdr_dump,
};
static const struct nft_expr_ops nft_exthdr_tcp_ops = {
.type = &nft_exthdr_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
.eval = nft_exthdr_tcp_eval,
.init = nft_exthdr_init,
.dump = nft_exthdr_dump,
};
static const struct nft_expr_ops *
nft_exthdr_select_ops(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
{
u32 op;
if (!tb[NFTA_EXTHDR_OP])
return &nft_exthdr_ipv6_ops;
op = ntohl(nla_get_u32(tb[NFTA_EXTHDR_OP]));
switch (op) {
case NFT_EXTHDR_OP_TCPOPT:
return &nft_exthdr_tcp_ops;
case NFT_EXTHDR_OP_IPV6:
return &nft_exthdr_ipv6_ops;
}
return ERR_PTR(-EOPNOTSUPP);
}
static struct nft_expr_type nft_exthdr_type __read_mostly = {
.name = "exthdr",
.select_ops = nft_exthdr_select_ops,
.policy = nft_exthdr_policy,
.maxattr = NFTA_EXTHDR_MAX,
.owner = THIS_MODULE,
};
static int __init nft_exthdr_module_init(void)
{
return nft_register_expr(&nft_exthdr_type);
}
static void __exit nft_exthdr_module_exit(void)
{
nft_unregister_expr(&nft_exthdr_type);
}
module_init(nft_exthdr_module_init);
module_exit(nft_exthdr_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_ALIAS_NFT_EXPR("exthdr");
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