linux-kernel - [PATCH 4.0 15/55] ip: report the original address of ICMP messages

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Message-Id: <20150708073239.728698004@linuxfoundation.org>
Date:	Wed,  8 Jul 2015 00:34:50 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Julian Anastasov <ja@....bg>,
	Willem de Bruijn <willemb@...gle.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.0 15/55] ip: report the original address of ICMP messages

4.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Julian Anastasov <ja@....bg>

[ Upstream commit 34b99df4e6256ddafb663c6de0711dceceddfe0e ]

ICMP messages can trigger ICMP and local errors. In this case
serr->port is 0 and starting from Linux 4.0 we do not return
the original target address to the error queue readers.
Add function to define which errors provide addr_offset.
With this fix my ping command is not silent anymore.

Fixes: c247f0534cc5 ("ip: fix error queue empty skb handling")
Signed-off-by: Julian Anastasov <ja@....bg>
Acked-by: Willem de Bruijn <willemb@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/ip_sockglue.c |   11 ++++++++++-
 net/ipv6/datagram.c    |   12 +++++++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)

--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -432,6 +432,15 @@ void ip_local_error(struct sock *sk, int
 		kfree_skb(skb);
 }
 
+/* For some errors we have valid addr_offset even with zero payload and
+ * zero port. Also, addr_offset should be supported if port is set.
+ */
+static inline bool ipv4_datagram_support_addr(struct sock_exterr_skb *serr)
+{
+	return serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
+	       serr->ee.ee_origin == SO_EE_ORIGIN_LOCAL || serr->port;
+}
+
 /* IPv4 supports cmsg on all imcp errors and some timestamps
  *
  * Timestamp code paths do not initialize the fields expected by cmsg:
@@ -498,7 +507,7 @@ int ip_recv_error(struct sock *sk, struc
 
 	serr = SKB_EXT_ERR(skb);
 
-	if (sin && serr->port) {
+	if (sin && ipv4_datagram_support_addr(serr)) {
 		sin->sin_family = AF_INET;
 		sin->sin_addr.s_addr = *(__be32 *)(skb_network_header(skb) +
 						   serr->addr_offset);
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -325,6 +325,16 @@ void ipv6_local_rxpmtu(struct sock *sk,
 	kfree_skb(skb);
 }
 
+/* For some errors we have valid addr_offset even with zero payload and
+ * zero port. Also, addr_offset should be supported if port is set.
+ */
+static inline bool ipv6_datagram_support_addr(struct sock_exterr_skb *serr)
+{
+	return serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6 ||
+	       serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
+	       serr->ee.ee_origin == SO_EE_ORIGIN_LOCAL || serr->port;
+}
+
 /* IPv6 supports cmsg on all origins aside from SO_EE_ORIGIN_LOCAL.
  *
  * At one point, excluding local errors was a quick test to identify icmp/icmp6
@@ -389,7 +399,7 @@ int ipv6_recv_error(struct sock *sk, str
 
 	serr = SKB_EXT_ERR(skb);
 
-	if (sin && serr->port) {
+	if (sin && ipv6_datagram_support_addr(serr)) {
 		const unsigned char *nh = skb_network_header(skb);
 		sin->sin6_family = AF_INET6;
 		sin->sin6_flowinfo = 0;


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