Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Xiumei Mu <xmu@redhat.com>,
        Sabrina Dubroca <sd@queasysnail.net>,
        Steffen Klassert <steffen.klassert@secunet.com>
Subject: [PATCH 5.4 38/85] xfrmi: drop ignore_df check before updating pmtu
Date:   Mon, 12 Oct 2020 15:27:01 +0200
Message-Id: <20201012132634.688974448@linuxfoundation.org>
In-Reply-To: <20201012132632.846779148@linuxfoundation.org>
References: <20201012132632.846779148@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Sabrina Dubroca <sd@queasysnail.net>

commit 45a36a18d01907710bad5258d81f76c18882ad88 upstream.

xfrm interfaces currently test for !skb->ignore_df when deciding
whether to update the pmtu on the skb's dst. Because of this, no pmtu
exception is created when we do something like:

    ping -s 1438 <dest>

By dropping this check, the pmtu exception will be created and the
next ping attempt will work.

Fixes: f203b76d7809 ("xfrm: Add virtual xfrm interfaces")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/xfrm/xfrm_interface.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -293,7 +293,7 @@ xfrmi_xmit2(struct sk_buff *skb, struct
 	}
 
 	mtu = dst_mtu(dst);
-	if (!skb->ignore_df && skb->len > mtu) {
+	if (skb->len > mtu) {
 		skb_dst_update_pmtu_no_confirm(skb, mtu);
 
 		if (skb->protocol == htons(ETH_P_IPV6)) {