gre: do not pull header in ICMP error processing

Jiri Benc · davem330 · commit b7f8fe251e46 · 2016-05-02T00:19:58.000-04:00
iptunnel_pull_header expects that IP header was already pulled; with this expectation, it pulls the tunnel header. This is not true in gre_err. Furthermore, ipv4_update_pmtu and ipv4_redirect expect that skb->data points to the IP header. We cannot pull the tunnel header in this path. It's just a matter of not calling iptunnel_pull_header - we don't need any of its effects. Fixes: bda7bb4 ("gre: Allow multiple protocol listener for gre protocol.") Signed-off-by: Jiri Benc <jbenc@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
@@ -179,6 +179,7 @@ static __be16 tnl_flags_to_gre_flags(__be16 tflags)
 	return flags;
 }
 
+/* Fills in tpi and returns header length to be pulled. */
 static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
 			    bool *csum_err)
 {
@@ -238,7 +239,7 @@ static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
 				return -EINVAL;
 		}
 	}
-	return iptunnel_pull_header(skb, hdr_len, tpi->proto, false);
+	return hdr_len;
 }
 
 static void ipgre_err(struct sk_buff *skb, u32 info,
@@ -341,7 +342,7 @@ static void gre_err(struct sk_buff *skb, u32 info)
 	struct tnl_ptk_info tpi;
 	bool csum_err = false;
 
-	if (parse_gre_header(skb, &tpi, &csum_err)) {
+	if (parse_gre_header(skb, &tpi, &csum_err) < 0) {
 		if (!csum_err)		/* ignore csum errors. */
 			return;
 	}
@@ -419,6 +420,7 @@ static int gre_rcv(struct sk_buff *skb)
 {
 	struct tnl_ptk_info tpi;
 	bool csum_err = false;
+	int hdr_len;
 
 #ifdef CONFIG_NET_IPGRE_BROADCAST
 	if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
@@ -428,7 +430,10 @@ static int gre_rcv(struct sk_buff *skb)
 	}
 #endif
 
-	if (parse_gre_header(skb, &tpi, &csum_err) < 0)
+	hdr_len = parse_gre_header(skb, &tpi, &csum_err);
+	if (hdr_len < 0)
+		goto drop;
+	if (iptunnel_pull_header(skb, hdr_len, tpi.proto, false) < 0)
 		goto drop;
 
 	if (ipgre_rcv(skb, &tpi) == PACKET_RCVD)

Original file line number	Diff line number	Diff line change
`@@ -179,6 +179,7 @@ static __be16 tnl_flags_to_gre_flags(__be16 tflags)`
`179`	`179`	`return flags;`
`180`	`180`	`}`
`181`	`181`
	`182`	`+/* Fills in tpi and returns header length to be pulled. */`
`182`	`183`	`static int parse_gre_header(struct sk_buff skb, struct tnl_ptk_info tpi,`
`183`	`184`	`bool *csum_err)`
`184`	`185`	`{`
`@@ -238,7 +239,7 @@ static int parse_gre_header(struct sk_buff skb, struct tnl_ptk_info tpi,`
`238`	`239`	`return -EINVAL;`
`239`	`240`	`}`
`240`	`241`	`}`
`241`		`- return iptunnel_pull_header(skb, hdr_len, tpi->proto, false);`
	`242`	`+ return hdr_len;`
`242`	`243`	`}`
`243`	`244`
`244`	`245`	`static void ipgre_err(struct sk_buff *skb, u32 info,`
`@@ -341,7 +342,7 @@ static void gre_err(struct sk_buff *skb, u32 info)`
`341`	`342`	`struct tnl_ptk_info tpi;`
`342`	`343`	`bool csum_err = false;`
`343`	`344`
`344`		`- if (parse_gre_header(skb, &tpi, &csum_err)) {`
	`345`	`+ if (parse_gre_header(skb, &tpi, &csum_err) < 0) {`
`345`	`346`	`if (!csum_err) /* ignore csum errors. */`
`346`	`347`	`return;`
`347`	`348`	`}`
`@@ -419,6 +420,7 @@ static int gre_rcv(struct sk_buff *skb)`
`419`	`420`	`{`
`420`	`421`	`struct tnl_ptk_info tpi;`
`421`	`422`	`bool csum_err = false;`
	`423`	`+ int hdr_len;`
`422`	`424`
`423`	`425`	`#ifdef CONFIG_NET_IPGRE_BROADCAST`
`424`	`426`	`if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {`
`@@ -428,7 +430,10 @@ static int gre_rcv(struct sk_buff *skb)`
`428`	`430`	`}`
`429`	`431`	`#endif`
`430`	`432`
`431`		`- if (parse_gre_header(skb, &tpi, &csum_err) < 0)`
	`433`	`+ hdr_len = parse_gre_header(skb, &tpi, &csum_err);`
	`434`	`+ if (hdr_len < 0)`
	`435`	`+ goto drop;`
	`436`	`+ if (iptunnel_pull_header(skb, hdr_len, tpi.proto, false) < 0)`
`432`	`437`	`goto drop;`
`433`	`438`
`434`	`439`	`if (ipgre_rcv(skb, &tpi) == PACKET_RCVD)`