diff options
| author | Florian Westphal <fw@strlen.de> | 2017-03-24 19:42:37 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-03-24 19:27:44 -0700 |
| commit | 28ee1b746f493b7c62347d714f58fbf4f70df4f0 (patch) | |
| tree | 852380c08234ff831bcf3177a21bcbeba0329b1f /net/core/secure_seq.c | |
| parent | 95f255211396958c718aef8c45e3923b5211ea7b (diff) | |
secure_seq: downgrade to per-host timestamp offsets
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.
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Reported-by: Yvan Vanrossomme <yvan@vanrossomme.net>
Fixes: 95a22caee396c ("tcp: randomize tcp timestamp offsets for each connection")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/secure_seq.c')
| -rw-r--r-- | net/core/secure_seq.c | 31 |
1 files changed, 29 insertions, 2 deletions
diff --git a/net/core/secure_seq.c b/net/core/secure_seq.c index 758f140b6bed..d28da7d363f1 100644 --- a/net/core/secure_seq.c +++ b/net/core/secure_seq.c @@ -20,9 +20,11 @@ #include <net/tcp.h> static siphash_key_t net_secret __read_mostly; +static siphash_key_t ts_secret __read_mostly; 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 @@ -45,6 +47,23 @@ static u32 seq_scale(u32 seq) #endif #if IS_ENABLED(CONFIG_IPV6) +static u32 secure_tcpv6_ts_off(const __be32 *saddr, const __be32 *daddr) +{ + const struct { + struct in6_addr saddr; + struct in6_addr daddr; + } __aligned(SIPHASH_ALIGNMENT) combined = { + .saddr = *(struct in6_addr *)saddr, + .daddr = *(struct in6_addr *)daddr, + }; + + if (sysctl_tcp_timestamps != 1) + return 0; + + return siphash(&combined, offsetofend(typeof(combined), daddr), + &ts_secret); +} + u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr, __be16 sport, __be16 dport, u32 *tsoff) { @@ -63,7 +82,7 @@ u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr, net_secret_init(); hash = siphash(&combined, offsetofend(typeof(combined), dport), &net_secret); - *tsoff = sysctl_tcp_timestamps == 1 ? (hash >> 32) : 0; + *tsoff = secure_tcpv6_ts_off(saddr, daddr); return seq_scale(hash); } EXPORT_SYMBOL(secure_tcpv6_sequence_number); @@ -88,6 +107,14 @@ 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 siphash_2u32((__force u32)saddr, (__force u32)daddr, + &ts_secret); +} /* secure_tcp_sequence_number(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d), * but fortunately, `sport' cannot be 0 in any circumstances. If this changes, @@ -103,7 +130,7 @@ u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr, hash = siphash_3u32((__force u32)saddr, (__force u32)daddr, (__force u32)sport << 16 | (__force u32)dport, &net_secret); - *tsoff = sysctl_tcp_timestamps == 1 ? (hash >> 32) : 0; + *tsoff = secure_tcp_ts_off(saddr, daddr); return seq_scale(hash); } |