From e7a409c3f46cb0dbc7bfd4f6f9421d53e92614a5 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 19 Oct 2019 09:26:37 -0700 Subject: [PATCH] ipv4: fix IPSKB_FRAG_PMTU handling with fragmentation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: 19c3401a917b ("net: ipv4: place control buffer handling away from fragmentation iterators") Reported-by: Patrick Schönthaler Signed-off-by: Eric Dumazet Signed-off-by: Pablo Neira Ayuso Signed-off-by: Linus Torvalds Signed-off-by: David S. Miller --- include/net/ip.h | 4 ++-- net/bridge/netfilter/nf_conntrack_bridge.c | 2 +- net/ipv4/ip_output.c | 11 ++++++----- 3 files changed, 9 insertions(+), 8 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index 95bb77f95bcc..a2c61c36dc4a 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -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); diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c index 506d6141e44e..809673222382 100644 --- a/net/bridge/netfilter/nf_conntrack_bridge.c +++ b/net/bridge/netfilter/nf_conntrack_bridge.c @@ -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; diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 814b9b8882a0..3d8baaaf7086 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -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.