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ipv4: fix IPSKB_FRAG_PMTU handling with fragmentation

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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: 19c3401a91 ("net: ipv4: place control buffer handling away from fragmentation iterators")
Reported-by: Patrick Schönthaler <patrick@notvads.ovh>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2019-10-19 09:26:37 -07:00 committed by David S. Miller
parent 40c5b2bd24
commit e7a409c3f4
3 changed files with 9 additions and 8 deletions
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4
include/net/ip.h
View File

@ -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);

2
net/bridge/netfilter/nf_conntrack_bridge.c
View File

@ -95,7 +95,7 @@ static int nf_br_ip_fragment(struct net *net, struct sock *sk,
* 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;

11
net/ipv4/ip_output.c
View File

@ -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 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
* 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.