Patch "netfilter: nft_exthdr: Support SCTP chunks" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    netfilter: nft_exthdr: Support SCTP chunks

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfilter-nft_exthdr-support-sctp-chunks.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 71331e82d5403cc7493c9710166033b0e7b0e637
Author: Phil Sutter <phil@xxxxxx>
Date:   Tue May 4 17:54:06 2021 +0200

    netfilter: nft_exthdr: Support SCTP chunks
    
    [ Upstream commit 133dc203d77dff617d9c4673973ef3859be2c476 ]
    
    Chunks are SCTP header extensions similar in implementation to IPv6
    extension headers or TCP options. Reusing exthdr expression to find and
    extract field values from them is therefore pretty straightforward.
    
    For now, this supports extracting data from chunks at a fixed offset
    (and length) only - chunks themselves are an extensible data structure;
    in order to make all fields available, a nested extension search is
    needed.
    
    Signed-off-by: Phil Sutter <phil@xxxxxx>
    Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
    Stable-dep-of: 28427f368f0e ("netfilter: nft_exthdr: Fix non-linear header modification")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 98272cb5f6178..1d8dd58f83a50 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -797,11 +797,13 @@ enum nft_exthdr_flags {
  * @NFT_EXTHDR_OP_IPV6: match against ipv6 extension headers
  * @NFT_EXTHDR_OP_TCP: match against tcp options
  * @NFT_EXTHDR_OP_IPV4: match against ipv4 options
+ * @NFT_EXTHDR_OP_SCTP: match against sctp chunks
  */
 enum nft_exthdr_op {
 	NFT_EXTHDR_OP_IPV6,
 	NFT_EXTHDR_OP_TCPOPT,
 	NFT_EXTHDR_OP_IPV4,
+	NFT_EXTHDR_OP_SCTP,
 	__NFT_EXTHDR_OP_MAX
 };
 #define NFT_EXTHDR_OP_MAX	(__NFT_EXTHDR_OP_MAX - 1)
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index 670dd146fb2b1..2f852ea67e5d5 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -10,8 +10,10 @@
 #include <linux/netlink.h>
 #include <linux/netfilter.h>
 #include <linux/netfilter/nf_tables.h>
+#include <linux/sctp.h>
 #include <net/netfilter/nf_tables_core.h>
 #include <net/netfilter/nf_tables.h>
+#include <net/sctp/sctp.h>
 #include <net/tcp.h>
 
 struct nft_exthdr {
@@ -303,6 +305,43 @@ static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr,
 	}
 }
 
+static void nft_exthdr_sctp_eval(const struct nft_expr *expr,
+				 struct nft_regs *regs,
+				 const struct nft_pktinfo *pkt)
+{
+	unsigned int offset = pkt->xt.thoff + sizeof(struct sctphdr);
+	struct nft_exthdr *priv = nft_expr_priv(expr);
+	u32 *dest = &regs->data[priv->dreg];
+	const struct sctp_chunkhdr *sch;
+	struct sctp_chunkhdr _sch;
+
+	do {
+		sch = skb_header_pointer(pkt->skb, offset, sizeof(_sch), &_sch);
+		if (!sch || !sch->length)
+			break;
+
+		if (sch->type == priv->type) {
+			if (priv->flags & NFT_EXTHDR_F_PRESENT) {
+				nft_reg_store8(dest, true);
+				return;
+			}
+			if (priv->offset + priv->len > ntohs(sch->length) ||
+			    offset + ntohs(sch->length) > pkt->skb->len)
+				break;
+
+			dest[priv->len / NFT_REG32_SIZE] = 0;
+			memcpy(dest, (char *)sch + priv->offset, priv->len);
+			return;
+		}
+		offset += SCTP_PAD4(ntohs(sch->length));
+	} while (offset < pkt->skb->len);
+
+	if (priv->flags & NFT_EXTHDR_F_PRESENT)
+		nft_reg_store8(dest, false);
+	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 },
@@ -502,6 +541,14 @@ static const struct nft_expr_ops nft_exthdr_tcp_set_ops = {
 	.dump		= nft_exthdr_dump_set,
 };
 
+static const struct nft_expr_ops nft_exthdr_sctp_ops = {
+	.type		= &nft_exthdr_type,
+	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
+	.eval		= nft_exthdr_sctp_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[])
@@ -532,6 +579,10 @@ nft_exthdr_select_ops(const struct nft_ctx *ctx,
 				return &nft_exthdr_ipv4_ops;
 		}
 		break;
+	case NFT_EXTHDR_OP_SCTP:
+		if (tb[NFTA_EXTHDR_DREG])
+			return &nft_exthdr_sctp_ops;
+		break;
 	}
 
 	return ERR_PTR(-EOPNOTSUPP);