ipv4: fix IPSKB_FRAG_PMTU handling with fragmentation

BugLink: https://bugs.launchpad.net/bugs/1852111
[ Upstream commit e7a409c3f46cb0dbc7bfd4f6f9421d53e92614a5 ]

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 <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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/include/net/ip.h b/include/net/ip.h
index 29d89de39822288f7b61d20c96374cfed5f6b8fb..e6609ab69161ef023cc20303bfc1d6fdb277a0db 100644 (file)
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -184,7 +184,7 @@ 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;
@@ -195,7 +195,7 @@ 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 4f5444d2a526a3dfb72a322ca1ec9c94ad0440ef..b3866536a0da17a83c34f3970c1eface1f590d09 100644 (file)
--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -94,7 +94,7 @@ 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 da521790cd6382ef07dec1b2254d56692f5a8f2e..be64c4a210fabf7ccdcd49a1b15b9b360c615659 100644 (file)
--- 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
@@ -881,7 +881,8 @@ 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.