Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec

Steffen Klassert says:

====================
ipsec 2022-06-01

1) Revert "net: af_key: add check for pfkey_broadcast in function pfkey_process"
   From Michal Kubecek.

2) Don't set IPv4 DF bit when encapsulating IPv6 frames below 1280 bytes.
   From Maciej Żenczykowski.

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec:
  xfrm: do not set IPv4 DF flag when encapsulating IPv6 frames <= 1280 bytes.
  Revert "net: af_key: add check for pfkey_broadcast in function pfkey_process"
====================

Link: https://lore.kernel.org/r/20220601103349.2297361-1-steffen.klassert@secunet.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

net/key/af_key.c

@@ -2826,10 +2826,12 @@ static int pfkey_process(struct sock *sk, struct sk_buff *skb, const struct sadb
 	void *ext_hdrs[SADB_EXT_MAX];
 	int err;
 
-	err = pfkey_broadcast(skb_clone(skb, GFP_KERNEL), GFP_KERNEL,
-			      BROADCAST_PROMISC_ONLY, NULL, sock_net(sk));
-	if (err)
-		return err;
+	/* Non-zero return value of pfkey_broadcast() does not always signal
+	 * an error and even on an actual error we may still want to process
+	 * the message so rather ignore the return value.
+	 */
+	pfkey_broadcast(skb_clone(skb, GFP_KERNEL), GFP_KERNEL,
+			BROADCAST_PROMISC_ONLY, NULL, sock_net(sk));
 
 	memset(ext_hdrs, 0, sizeof(ext_hdrs));
 	err = parse_exthdrs(skb, hdr, ext_hdrs);

net/xfrm/xfrm_output.c

@@ -273,6 +273,7 @@ static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
  */
 static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
 {
+	bool small_ipv6 = (skb->protocol == htons(ETH_P_IPV6)) && (skb->len <= IPV6_MIN_MTU);
 	struct dst_entry *dst = skb_dst(skb);
 	struct iphdr *top_iph;
 	int flags;
@@ -303,7 +304,7 @@ static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
 	if (flags & XFRM_STATE_NOECN)
 		IP_ECN_clear(top_iph);
 
-	top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
+	top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) || small_ipv6 ?
 		0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
 
 	top_iph->ttl = ip4_dst_hoplimit(xfrm_dst_child(dst));