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netfilter: nft_exthdr: add boolean DCCP option matching 

[ Upstream commit b9f9a485fb ]

The xt_dccp iptables module supports the matching of DCCP packets based
on the presence or absence of DCCP options.  Extend nft_exthdr to add
this functionality to nftables.

Link: https://bugzilla.netfilter.org/show_bug.cgi?id=930
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Stable-dep-of: 63331e37fb ("netfilter: nf_tables: fix 'exist' matching on bigendian arches")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jeremy Sowden 2023-05-09 22:19:45 +01:00 committed by Greg Kroah-Hartman
parent 9225a4566b
commit 0bfbfd9423
2 changed files with 108 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/uapi/linux/netfilter/nf_tables.h
View File

@ -816,12 +816,14 @@ enum nft_exthdr_flags {
* @NFT_EXTHDR_OP_TCP: match against tcp options
* @NFT_EXTHDR_OP_IPV4: match against ipv4 options
* @NFT_EXTHDR_OP_SCTP: match against sctp chunks
* @NFT_EXTHDR_OP_DCCP: match against dccp otions
*/
enum nft_exthdr_op {
NFT_EXTHDR_OP_IPV6,
NFT_EXTHDR_OP_TCPOPT,
NFT_EXTHDR_OP_IPV4,
NFT_EXTHDR_OP_SCTP,
NFT_EXTHDR_OP_DCCP,
__NFT_EXTHDR_OP_MAX
};
#define NFT_EXTHDR_OP_MAX (__NFT_EXTHDR_OP_MAX - 1)

106
net/netfilter/nft_exthdr.c
View File

@ -10,6 +10,7 @@
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <linux/dccp.h>
#include <linux/sctp.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
@ -409,6 +410,82 @@ err:
regs->verdict.code = NFT_BREAK;
}
static void nft_exthdr_dccp_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_exthdr *priv = nft_expr_priv(expr);
unsigned int thoff, dataoff, optoff, optlen, i;
u32 *dest = &regs->data[priv->dreg];
const struct dccp_hdr *dh;
struct dccp_hdr _dh;
if (pkt->tprot != IPPROTO_DCCP || pkt->fragoff)
goto err;
thoff = nft_thoff(pkt);
dh = skb_header_pointer(pkt->skb, thoff, sizeof(_dh), &_dh);
if (!dh)
goto err;
dataoff = dh->dccph_doff * sizeof(u32);
optoff = __dccp_hdr_len(dh);
if (dataoff <= optoff)
goto err;
optlen = dataoff - optoff;
for (i = 0; i < optlen; ) {
/* Options 0 (DCCPO_PADDING) - 31 (DCCPO_MAX_RESERVED) are 1B in
* the length; the remaining options are at least 2B long. In
* all cases, the first byte contains the option type. In
* multi-byte options, the second byte contains the option
* length, which must be at least two: 1 for the type plus 1 for
* the length plus 0-253 for any following option data. We
* aren't interested in the option data, only the type and the
* length, so we don't need to read more than two bytes at a
* time.
*/
unsigned int buflen = optlen - i;
u8 buf[2], *bufp;
u8 type, len;
if (buflen > sizeof(buf))
buflen = sizeof(buf);
bufp = skb_header_pointer(pkt->skb, thoff + optoff + i, buflen,
&buf);
if (!bufp)
goto err;
type = bufp[0];
if (type == priv->type) {
*dest = 1;
return;
}
if (type <= DCCPO_MAX_RESERVED) {
i++;
continue;
}
if (buflen < 2)
goto err;
len = bufp[1];
if (len < 2)
goto err;
i += len;
}
err:
*dest = 0;
}
static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
[NFTA_EXTHDR_DREG] = { .type = NLA_U32 },
[NFTA_EXTHDR_TYPE] = { .type = NLA_U8 },
@ -560,6 +637,22 @@ static int nft_exthdr_ipv4_init(const struct nft_ctx *ctx,
return 0;
}
static int nft_exthdr_dccp_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_exthdr *priv = nft_expr_priv(expr);
int err = nft_exthdr_init(ctx, expr, tb);
if (err < 0)
return err;
if (!(priv->flags & NFT_EXTHDR_F_PRESENT))
return -EOPNOTSUPP;
return 0;
}
static int nft_exthdr_dump_common(struct sk_buff *skb, const struct nft_exthdr *priv)
{
if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
@ -686,6 +779,15 @@ static const struct nft_expr_ops nft_exthdr_sctp_ops = {
.reduce = nft_exthdr_reduce,
};
static const struct nft_expr_ops nft_exthdr_dccp_ops = {
.type = &nft_exthdr_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
.eval = nft_exthdr_dccp_eval,
.init = nft_exthdr_dccp_init,
.dump = nft_exthdr_dump,
.reduce = nft_exthdr_reduce,
};
static const struct nft_expr_ops *
nft_exthdr_select_ops(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
@ -720,6 +822,10 @@ nft_exthdr_select_ops(const struct nft_ctx *ctx,
if (tb[NFTA_EXTHDR_DREG])
return &nft_exthdr_sctp_ops;
break;
case NFT_EXTHDR_OP_DCCP:
if (tb[NFTA_EXTHDR_DREG])
return &nft_exthdr_dccp_ops;
break;
}
return ERR_PTR(-EOPNOTSUPP);