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Commit 03606895 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipsec: be careful of non existing mac headers 

Niccolo Belli reported ipsec crashes in case we handle a frame without
mac header (atm in his case)

Before copying mac header, better make sure it is present.

Bugzilla reference:  https://bugzilla.kernel.org/show_bug.cgi?id=42809



Reported-by: default avatarNiccolò Belli <darkbasic@linuxsystems.it>
Tested-by: default avatarNiccolò Belli <darkbasic@linuxsystems.it>
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4a2258dd

include/linux/skbuff.h

+10 −0
Original line number Diff line number Diff line
@@ -1465,6 +1465,16 @@ static inline void skb_set_mac_header(struct sk_buff *skb, const int offset) 
}

#endif /* NET_SKBUFF_DATA_USES_OFFSET */



static inline void skb_mac_header_rebuild(struct sk_buff *skb)

{

	if (skb_mac_header_was_set(skb)) {

		const unsigned char *old_mac = skb_mac_header(skb);



		skb_set_mac_header(skb, -skb->mac_len);

		memmove(skb_mac_header(skb), old_mac, skb->mac_len);

	}

}



static inline int skb_checksum_start_offset(const struct sk_buff *skb)

{

	return skb->csum_start - skb_headroom(skb);

net/ipv4/xfrm4_mode_beet.c

+1 −4
Original line number Diff line number Diff line
@@ -110,10 +110,7 @@ static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb) 


	skb_push(skb, sizeof(*iph));

	skb_reset_network_header(skb);



	memmove(skb->data - skb->mac_len, skb_mac_header(skb),

		skb->mac_len);

	skb_set_mac_header(skb, -skb->mac_len);

	skb_mac_header_rebuild(skb);



	xfrm4_beet_make_header(skb);

net/ipv4/xfrm4_mode_tunnel.c

+2 −4
Original line number Diff line number Diff line
@@ -66,7 +66,6 @@ static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb) 


static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)

{

	const unsigned char *old_mac;

	int err = -EINVAL;



	if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
@@ -84,10 +83,9 @@ static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb) 
	if (!(x->props.flags & XFRM_STATE_NOECN))

		ipip_ecn_decapsulate(skb);



	old_mac = skb_mac_header(skb);

	skb_set_mac_header(skb, -skb->mac_len);

	memmove(skb_mac_header(skb), old_mac, skb->mac_len);

	skb_reset_network_header(skb);

	skb_mac_header_rebuild(skb);



	err = 0;



out:

net/ipv6/xfrm6_mode_beet.c

+1 −5
Original line number Diff line number Diff line
@@ -80,7 +80,6 @@ static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb) 
static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)

{

	struct ipv6hdr *ip6h;

	const unsigned char *old_mac;

	int size = sizeof(struct ipv6hdr);

	int err;
@@ -90,10 +89,7 @@ static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb) 


	__skb_push(skb, size);

	skb_reset_network_header(skb);



	old_mac = skb_mac_header(skb);

	skb_set_mac_header(skb, -skb->mac_len);

	memmove(skb_mac_header(skb), old_mac, skb->mac_len);

	skb_mac_header_rebuild(skb);



	xfrm6_beet_make_header(skb);

net/ipv6/xfrm6_mode_tunnel.c

+2 −4
Original line number Diff line number Diff line
@@ -63,7 +63,6 @@ static int xfrm6_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb) 
static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)

{

	int err = -EINVAL;

	const unsigned char *old_mac;



	if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)

		goto out;
@@ -80,10 +79,9 @@ static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb) 
	if (!(x->props.flags & XFRM_STATE_NOECN))

		ipip6_ecn_decapsulate(skb);



	old_mac = skb_mac_header(skb);

	skb_set_mac_header(skb, -skb->mac_len);

	memmove(skb_mac_header(skb), old_mac, skb->mac_len);

	skb_reset_network_header(skb);

	skb_mac_header_rebuild(skb);



	err = 0;



out: