4.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Florian Westphal <fw@xxxxxxxxx>
[ Upstream commit 28ee1b746f493b7c62347d714f58fbf4f70df4f0 ]
Unfortunately too many devices (not under our control) use tcp_tw_recycle=1,
which depends on timestamps being identical of the same saddr.
Although tcp_tw_recycle got removed in net-next we can't make
such end hosts disappear so downgrade to per-host timestamp offsets.
4.10 note: original patch uses siphash (added in 4.11), since
ts_off is only used to obscure uptime (and doesn't use same secret
as isn generator) this uses jhash instead.
Cc: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Neal Cardwell <ncardwell@xxxxxxxxxx>
Cc: Yuchung Cheng <ycheng@xxxxxxxxxx>
Reported-by: Yvan Vanrossomme <yvan@xxxxxxxxxxxxxxx>
Fixes: 95a22caee396c ("tcp: randomize tcp timestamp offsets for each connection")
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/secure_seq.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)
--- a/net/core/secure_seq.c
+++ b/net/core/secure_seq.c
@@ -16,9 +16,11 @@
#define NET_SECRET_SIZE (MD5_MESSAGE_BYTES / 4)
static u32 net_secret[NET_SECRET_SIZE] ____cacheline_aligned;
+static u32 ts_secret[2];
static __always_inline void net_secret_init(void)
{
+ net_get_random_once(ts_secret, sizeof(ts_secret));
net_get_random_once(net_secret, sizeof(net_secret));
}
#endif
@@ -41,6 +43,21 @@ static u32 seq_scale(u32 seq)
#endif
#if IS_ENABLED(CONFIG_IPV6)
+static u32 secure_tcpv6_ts_off(const __be32 *saddr, const __be32 *daddr)
+{
+ u32 hash[4 + 4 + 1];
+
+ if (sysctl_tcp_timestamps != 1)
+ return 0;
+
+ memcpy(hash, saddr, 16);
+ memcpy(hash + 4, daddr, 16);
+
+ hash[8] = ts_secret[0];
+
+ return jhash2(hash, ARRAY_SIZE(hash), ts_secret[1]);
+}
+
u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
__be16 sport, __be16 dport, u32 *tsoff)
{
@@ -59,7 +76,7 @@ u32 secure_tcpv6_sequence_number(const _
md5_transform(hash, secret);
- *tsoff = sysctl_tcp_timestamps == 1 ? hash[1] : 0;
+ *tsoff = secure_tcpv6_ts_off(saddr, daddr);
return seq_scale(hash[0]);
}
EXPORT_SYMBOL(secure_tcpv6_sequence_number);
@@ -87,6 +104,14 @@ EXPORT_SYMBOL(secure_ipv6_port_ephemeral
#endif
#ifdef CONFIG_INET
+static u32 secure_tcp_ts_off(__be32 saddr, __be32 daddr)
+{
+ if (sysctl_tcp_timestamps != 1)
+ return 0;
+
+ return jhash_3words((__force u32)saddr, (__force u32)daddr,
+ ts_secret[0], ts_secret[1]);
+}
u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport, u32 *tsoff)
@@ -101,7 +126,7 @@ u32 secure_tcp_sequence_number(__be32 sa
md5_transform(hash, net_secret);
- *tsoff = sysctl_tcp_timestamps == 1 ? hash[1] : 0;
+ *tsoff = secure_tcp_ts_off(saddr, daddr);
return seq_scale(hash[0]);
}