[PATCH 5.15 057/230] netfilter: nft_payload: support for inner header matching / mangling

Greg Kroah-Hartman
2022-07-11T09:45:19Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

[ Upstream commit c46b38dc8743535e686b911d253a844f0bd50ead ]

Allow to match and mangle on inner headers / payload data after the
transport header. There is a new field in the pktinfo structure that
stores the inner header offset which is calculated only when requested.
Only TCP and UDP supported at this stage.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/netfilter/nf_tables.h | 2 +
include/uapi/linux/netfilter/nf_tables.h | 2 +
net/netfilter/nft_payload.c | 56 +++++++++++++++++++++++-
3 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index d005f87691da..bcfee89012a1 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -23,6 +23,7 @@ struct module;

enum {
NFT_PKTINFO_L4PROTO = (1 << 0),
+ NFT_PKTINFO_INNER = (1 << 1),
};

struct nft_pktinfo {
@@ -32,6 +33,7 @@ struct nft_pktinfo {
u8 tprot;
u16 fragoff;
unsigned int thoff;
+ unsigned int inneroff;
};

static inline struct sock *nft_sk(const struct nft_pktinfo *pkt)
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index e94d1fa554cb..07871c8a0601 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -753,11 +753,13 @@ enum nft_dynset_attributes {
* @NFT_PAYLOAD_LL_HEADER: link layer header
* @NFT_PAYLOAD_NETWORK_HEADER: network header
* @NFT_PAYLOAD_TRANSPORT_HEADER: transport header
+ * @NFT_PAYLOAD_INNER_HEADER: inner header / payload
*/
enum nft_payload_bases {
NFT_PAYLOAD_LL_HEADER,
NFT_PAYLOAD_NETWORK_HEADER,
NFT_PAYLOAD_TRANSPORT_HEADER,
+ NFT_PAYLOAD_INNER_HEADER,
};

/**
diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c
index c3ccfff54a35..ee359a4a60f5 100644
--- a/net/netfilter/nft_payload.c
+++ b/net/netfilter/nft_payload.c
@@ -22,6 +22,7 @@
#include <linux/icmpv6.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
+#include <linux/ip.h>
#include <net/sctp/checksum.h>

static bool nft_payload_rebuild_vlan_hdr(const struct sk_buff *skb, int mac_off,
@@ -79,6 +80,45 @@ nft_payload_copy_vlan(u32 *d, const struct sk_buff *skb, u8 offset, u8 len)
return skb_copy_bits(skb, offset + mac_off, dst_u8, len) == 0;
}

+static int __nft_payload_inner_offset(struct nft_pktinfo *pkt)
+{
+ unsigned int thoff = nft_thoff(pkt);
+
+ if (!(pkt->flags & NFT_PKTINFO_L4PROTO))
+ return -1;
+
+ switch (pkt->tprot) {
+ case IPPROTO_UDP:
+ pkt->inneroff = thoff + sizeof(struct udphdr);
+ break;
+ case IPPROTO_TCP: {
+ struct tcphdr *th, _tcph;
+
+ th = skb_header_pointer(pkt->skb, thoff, sizeof(_tcph), &_tcph);
+ if (!th)
+ return -1;
+
+ pkt->inneroff = thoff + __tcp_hdrlen(th);
+ }
+ break;
+ default:
+ return -1;
+ }
+
+ pkt->flags |= NFT_PKTINFO_INNER;
+
+ return 0;
+}
+
+static int nft_payload_inner_offset(const struct nft_pktinfo *pkt)
+{
+ if (!(pkt->flags & NFT_PKTINFO_INNER) &&
+ __nft_payload_inner_offset((struct nft_pktinfo *)pkt) < 0)
+ return -1;
+
+ return pkt->inneroff;
+}
+
void nft_payload_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
@@ -112,6 +152,11 @@ void nft_payload_eval(const struct nft_expr *expr,
goto err;
offset = nft_thoff(pkt);
break;
+ case NFT_PAYLOAD_INNER_HEADER:
+ offset = nft_payload_inner_offset(pkt);
+ if (offset < 0)
+ goto err;
+ break;
default:
BUG();
}
@@ -617,6 +662,11 @@ static void nft_payload_set_eval(const struct nft_expr *expr,
goto err;
offset = nft_thoff(pkt);
break;
+ case NFT_PAYLOAD_INNER_HEADER:
+ offset = nft_payload_inner_offset(pkt);
+ if (offset < 0)
+ goto err;
+ break;
default:
BUG();
}
@@ -625,7 +675,8 @@ static void nft_payload_set_eval(const struct nft_expr *expr,
offset += priv->offset;

if ((priv->csum_type == NFT_PAYLOAD_CSUM_INET || priv->csum_flags) &&
- (priv->base != NFT_PAYLOAD_TRANSPORT_HEADER ||
+ ((priv->base != NFT_PAYLOAD_TRANSPORT_HEADER &&
+ priv->base != NFT_PAYLOAD_INNER_HEADER) ||
skb->ip_summed != CHECKSUM_PARTIAL)) {
fsum = skb_checksum(skb, offset, priv->len, 0);
tsum = csum_partial(src, priv->len, 0);
@@ -744,6 +795,7 @@ nft_payload_select_ops(const struct nft_ctx *ctx,
case NFT_PAYLOAD_LL_HEADER:
case NFT_PAYLOAD_NETWORK_HEADER:
case NFT_PAYLOAD_TRANSPORT_HEADER:
+ case NFT_PAYLOAD_INNER_HEADER:
break;
default:
return ERR_PTR(-EOPNOTSUPP);
@@ -762,7 +814,7 @@ nft_payload_select_ops(const struct nft_ctx *ctx,
len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));

if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
- base != NFT_PAYLOAD_LL_HEADER)
+ base != NFT_PAYLOAD_LL_HEADER && base != NFT_PAYLOAD_INNER_HEADER)
return &nft_payload_fast_ops;
else
return &nft_payload_ops;
--
2.35.1