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authorFlorian Westphal <fw@strlen.de>2016-12-01 11:32:06 +0100
committerDavid S. Miller <davem@davemloft.net>2016-12-02 12:49:59 -0500
commit95a22caee396cef0bb2ca8fafdd82966a49367bb (patch)
treeba58ca9c85a73dc887096d8123d199b3d28a705c /net/ipv4/tcp_minisocks.c
parent7df5358d4707c6f0a26266d3a4dd97fd353947e2 (diff)
downloadlinux-95a22caee396cef0bb2ca8fafdd82966a49367bb.tar.bz2
tcp: randomize tcp timestamp offsets for each connection
jiffies based timestamps allow for easy inference of number of devices behind NAT translators and also makes tracking of hosts simpler. commit ceaa1fef65a7c2e ("tcp: adding a per-socket timestamp offset") added the main infrastructure that is needed for per-connection ts randomization, in particular writing/reading the on-wire tcp header format takes the offset into account so rest of stack can use normal tcp_time_stamp (jiffies). So only two items are left: - add a tsoffset for request sockets - extend the tcp isn generator to also return another 32bit number in addition to the ISN. Re-use of ISN generator also means timestamps are still monotonically increasing for same connection quadruple, i.e. PAWS will still work. Includes fixes from Eric Dumazet. Signed-off-by: Florian Westphal <fw@strlen.de> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_minisocks.c')
-rw-r--r--net/ipv4/tcp_minisocks.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 6234ebaa7db1..28ce5ee831f5 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -532,7 +532,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
newtp->rx_opt.ts_recent_stamp = 0;
newtp->tcp_header_len = sizeof(struct tcphdr);
}
- newtp->tsoffset = 0;
+ newtp->tsoffset = treq->ts_off;
#ifdef CONFIG_TCP_MD5SIG
newtp->md5sig_info = NULL; /*XXX*/
if (newtp->af_specific->md5_lookup(sk, newsk))
@@ -581,6 +581,8 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
if (tmp_opt.saw_tstamp) {
tmp_opt.ts_recent = req->ts_recent;
+ if (tmp_opt.rcv_tsecr)
+ tmp_opt.rcv_tsecr -= tcp_rsk(req)->ts_off;
/* We do not store true stamp, but it is not required,
* it can be estimated (approximately)
* from another data.