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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/core
parent7df5358d4707c6f0a26266d3a4dd97fd353947e2 (diff)
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/core')
-rw-r--r--net/core/secure_seq.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/net/core/secure_seq.c b/net/core/secure_seq.c
index fd3ce461fbe6..a8d6062cbb4a 100644
--- a/net/core/secure_seq.c
+++ b/net/core/secure_seq.c
@@ -40,8 +40,8 @@ static u32 seq_scale(u32 seq)
#endif
#if IS_ENABLED(CONFIG_IPV6)
-__u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
- __be16 sport, __be16 dport)
+u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
+ __be16 sport, __be16 dport, u32 *tsoff)
{
u32 secret[MD5_MESSAGE_BYTES / 4];
u32 hash[MD5_DIGEST_WORDS];
@@ -58,6 +58,7 @@ __u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
md5_transform(hash, secret);
+ *tsoff = hash[1];
return seq_scale(hash[0]);
}
EXPORT_SYMBOL(secure_tcpv6_sequence_number);
@@ -86,8 +87,8 @@ EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
#ifdef CONFIG_INET
-__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
- __be16 sport, __be16 dport)
+u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
+ __be16 sport, __be16 dport, u32 *tsoff)
{
u32 hash[MD5_DIGEST_WORDS];
@@ -99,6 +100,7 @@ __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
md5_transform(hash, net_secret);
+ *tsoff = hash[1];
return seq_scale(hash[0]);
}