netdev - [PATCH ipsec 2/2] xfrm: Log input direction mismatch error in one place

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Date: Tue, 11 Jun 2024 08:32:15 +0200
From: Antony Antony <antony.antony@...unet.com>
To: <netdev@...r.kernel.org>, Steffen Klassert <steffen.klassert@...unet.com>,
	Herbert Xu <herbert@...dor.apana.org.au>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Antony Antony <antony.antony@...unet.com>, "Sabrina
 Dubroca" <sd@...asysnail.net>
Subject: [PATCH ipsec 2/2] xfrm: Log input direction mismatch error in one
 place

Previously, the offload data path decrypted the packet before checking
the direction, leading to error logging and packet dropping. However,
dropped packets wouldn't be visible in tcpdump or audit log.

With this fix, the offload path, upon noticing SA direction mismatch,
will pass the packet to the stack without decrypting it. The L3 layer
will then log the error, audit, and drop ESP without decrypting or
decapsulating it.

This also ensures that the slow path records the error and audit log,
making dropped packets visible in tcpdump.

Fixes: 304b44f0d5a4 ("xfrm: Add dir validation to "in" data path lookup")
Signed-off-by: Antony Antony <antony.antony@...unet.com>
---
 net/ipv4/esp4_offload.c | 7 +++++++
 net/ipv6/esp6_offload.c | 7 +++++++
 net/xfrm/xfrm_input.c   | 5 -----
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index b3271957ad9a..3f28ecbdcaef 100644
--- a/net/ipv4/esp4_offload.c
+++ b/net/ipv4/esp4_offload.c
@@ -56,6 +56,13 @@ static struct sk_buff *esp4_gro_receive(struct list_head *head,
 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
 				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
 				      spi, IPPROTO_ESP, AF_INET);
+
+		if (unlikely(x && x->dir && x->dir != XFRM_SA_DIR_IN)) {
+			/* non-offload path will record the error and audit log */
+			xfrm_state_put(x);
+			x = NULL;
+		}
+
 		if (!x)
 			goto out_reset;
 
diff --git a/net/ipv6/esp6_offload.c b/net/ipv6/esp6_offload.c
index 527b7caddbc6..919ebfabbe4e 100644
--- a/net/ipv6/esp6_offload.c
+++ b/net/ipv6/esp6_offload.c
@@ -83,6 +83,13 @@ static struct sk_buff *esp6_gro_receive(struct list_head *head,
 		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
 				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 				      spi, IPPROTO_ESP, AF_INET6);
+
+		if (unlikely(x && x->dir && x->dir != XFRM_SA_DIR_IN)) {
+			/* non-offload path will record the error and audit log */
+			xfrm_state_put(x);
+			x = NULL;
+		}
+
 		if (!x)
 			goto out_reset;
 
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 63c004103912..e95462b982b0 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -474,11 +474,6 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 	if (encap_type < 0 || (xo && xo->flags & XFRM_GRO)) {
 		x = xfrm_input_state(skb);
 
-		if (unlikely(x->dir && x->dir != XFRM_SA_DIR_IN)) {
-			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATEDIRERROR);
-			goto drop;
-		}
-
 		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
 			if (x->km.state == XFRM_STATE_ACQ)
 				XFRM_INC_STATS(net, LINUX_MIB_XFRMACQUIREERROR);
-- 
2.30.2