Commit e7a409c3 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv4: fix IPSKB_FRAG_PMTU handling with fragmentation 



This patch removes the iph field from the state structure, which is not
properly initialized. Instead, add a new field to make the "do we want
to set DF" be the state bit and move the code to set the DF flag from
ip_frag_next().

Joint work with Pablo and Linus.

Fixes: 19c3401a ("net: ipv4: place control buffer handling away from fragmentation iterators")
Reported-by: default avatarPatrick Schönthaler <patrick@notvads.ovh>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 40c5b2bd

include/net/ip.h

+2 −2
Original line number Diff line number Diff line
@@ -185,7 +185,7 @@ static inline struct sk_buff *ip_fraglist_next(struct ip_fraglist_iter *iter) 
}



struct ip_frag_state {

	struct iphdr	*iph;

	bool		DF;

	unsigned int	hlen;

	unsigned int	ll_rs;

	unsigned int	mtu;
@@ -196,7 +196,7 @@ struct ip_frag_state { 
};



void ip_frag_init(struct sk_buff *skb, unsigned int hlen, unsigned int ll_rs,

		  unsigned int mtu, struct ip_frag_state *state);

		  unsigned int mtu, bool DF, struct ip_frag_state *state);

struct sk_buff *ip_frag_next(struct sk_buff *skb,

			     struct ip_frag_state *state);

net/bridge/netfilter/nf_conntrack_bridge.c

+1 −1
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ slow_path: 
	 * This may also be a clone skbuff, we could preserve the geometry for

	 * the copies but probably not worth the effort.

	 */

	ip_frag_init(skb, hlen, ll_rs, frag_max_size, &state);

	ip_frag_init(skb, hlen, ll_rs, frag_max_size, false, &state);



	while (state.left > 0) {

		struct sk_buff *skb2;

net/ipv4/ip_output.c

+6 −5
Original line number Diff line number Diff line
@@ -645,11 +645,12 @@ void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter) 
EXPORT_SYMBOL(ip_fraglist_prepare);



void ip_frag_init(struct sk_buff *skb, unsigned int hlen,

		  unsigned int ll_rs, unsigned int mtu,

		  unsigned int ll_rs, unsigned int mtu, bool DF,

		  struct ip_frag_state *state)

{

	struct iphdr *iph = ip_hdr(skb);



	state->DF = DF;

	state->hlen = hlen;

	state->ll_rs = ll_rs;

	state->mtu = mtu;
@@ -668,9 +669,6 @@ static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to, 
	/* Copy the flags to each fragment. */

	IPCB(to)->flags = IPCB(from)->flags;



	if (IPCB(from)->flags & IPSKB_FRAG_PMTU)

		state->iph->frag_off |= htons(IP_DF);



	/* ANK: dirty, but effective trick. Upgrade options only if

	 * the segment to be fragmented was THE FIRST (otherwise,

	 * options are already fixed) and make it ONCE
@@ -738,6 +736,8 @@ struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state) 
	 */

	iph = ip_hdr(skb2);

	iph->frag_off = htons((state->offset >> 3));

	if (state->DF)

		iph->frag_off |= htons(IP_DF);



	/*

	 *	Added AC : If we are fragmenting a fragment that's not the
@@ -883,7 +883,8 @@ slow_path: 
	 *	Fragment the datagram.

	 */



	ip_frag_init(skb, hlen, ll_rs, mtu, &state);

	ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,

		     &state);



	/*

	 *	Keep copying data until we run out.

CRA Git | Maintained and supported by SUSTech CRA and CCSE