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Diffstat (limited to 'net/ipv4/ip_output.c')
-rw-r--r--net/ipv4/ip_output.c26
1 files changed, 21 insertions, 5 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 57c1d8431386..139cec29ed06 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -162,12 +162,19 @@ int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
iph->saddr = saddr;
iph->protocol = sk->sk_protocol;
- if (ip_dont_fragment(sk, &rt->dst)) {
+ /* Do not bother generating IPID for small packets (eg SYNACK) */
+ if (skb->len <= IPV4_MIN_MTU || ip_dont_fragment(sk, &rt->dst)) {
iph->frag_off = htons(IP_DF);
iph->id = 0;
} else {
iph->frag_off = 0;
- __ip_select_ident(net, iph, 1);
+ /* TCP packets here are SYNACK with fat IPv4/TCP options.
+ * Avoid using the hashed IP ident generator.
+ */
+ if (sk->sk_protocol == IPPROTO_TCP)
+ iph->id = (__force __be16)prandom_u32();
+ else
+ __ip_select_ident(net, iph, 1);
}
if (opt && opt->opt.optlen) {
@@ -825,15 +832,24 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
/* Everything is OK. Generate! */
ip_fraglist_init(skb, iph, hlen, &iter);
- if (iter.frag)
- ip_options_fragment(iter.frag);
-
for (;;) {
/* Prepare header of the next frame,
* before previous one went down. */
if (iter.frag) {
+ bool first_frag = (iter.offset == 0);
+
IPCB(iter.frag)->flags = IPCB(skb)->flags;
ip_fraglist_prepare(skb, &iter);
+ if (first_frag && IPCB(skb)->opt.optlen) {
+ /* ipcb->opt is not populated for frags
+ * coming from __ip_make_skb(),
+ * ip_options_fragment() needs optlen
+ */
+ IPCB(iter.frag)->opt.optlen =
+ IPCB(skb)->opt.optlen;
+ ip_options_fragment(iter.frag);
+ ip_send_check(iter.iph);
+ }
}
skb->tstamp = tstamp;