Commit 8dfb4eba authored by Sabrina Dubroca's avatar Sabrina Dubroca Committed by Steffen Klassert
Browse files

esp4: add length check for UDP encapsulation 



esp_output_udp_encap can produce a length that doesn't fit in the 16
bits of a UDP header's length field. In that case, we'll send a
fragmented packet whose length is larger than IP_MAX_MTU (resulting in
"Oversized IP packet" warnings on receive) and with a bogus UDP
length.

To prevent this, add a length check to esp_output_udp_encap and return
 -EMSGSIZE on failure.

This seems to be older than git history.

Signed-off-by: default avatarSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent dbb2483b

net/ipv4/esp4.c

+15 −5
Original line number Diff line number Diff line
@@ -226,7 +226,7 @@ static void esp_output_fill_trailer(u8 *tail, int tfclen, int plen, __u8 proto) 
	tail[plen - 1] = proto;

}



static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)

static int esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)

{

	int encap_type;

	struct udphdr *uh;
@@ -234,6 +234,7 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru 
	__be16 sport, dport;

	struct xfrm_encap_tmpl *encap = x->encap;

	struct ip_esp_hdr *esph = esp->esph;

	unsigned int len;



	spin_lock_bh(&x->lock);

	sport = encap->encap_sport;
@@ -241,11 +242,14 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru 
	encap_type = encap->encap_type;

	spin_unlock_bh(&x->lock);



	len = skb->len + esp->tailen - skb_transport_offset(skb);

	if (len + sizeof(struct iphdr) >= IP_MAX_MTU)

		return -EMSGSIZE;



	uh = (struct udphdr *)esph;

	uh->source = sport;

	uh->dest = dport;

	uh->len = htons(skb->len + esp->tailen

		  - skb_transport_offset(skb));

	uh->len = htons(len);

	uh->check = 0;



	switch (encap_type) {
@@ -262,6 +266,8 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru 


	*skb_mac_header(skb) = IPPROTO_UDP;

	esp->esph = esph;



	return 0;

}



int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
@@ -275,8 +281,12 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info * 
	int tailen = esp->tailen;



	/* this is non-NULL only with UDP Encapsulation */

	if (x->encap)

		esp_output_udp_encap(x, skb, esp);

	if (x->encap) {

		int err = esp_output_udp_encap(x, skb, esp);



		if (err < 0)

			return err;

	}



	if (!skb_cloned(skb)) {

		if (tailen <= skb_tailroom(skb)) {

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