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Commit 6e34ee5b authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
Browse files

tcp: resalt the secret every 10 seconds 



[ Upstream commit 4dfa9b438ee34caca4e6a4e5e961641807367f6f ]

In order to limit the ability for an observer to recognize the source
ports sequence used to contact a set of destinations, we should
periodically shuffle the secret. 10 seconds looks effective enough
without causing particular issues.

Cc: Moshe Kol <moshe.kol@mail.huji.ac.il>
Cc: Yossi Gilad <yossi.gilad@mail.huji.ac.il>
Cc: Amit Klein <aksecurity@gmail.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Tested-by: default avatarWilly Tarreau <w@1wt.eu>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 39c26fe9

net/core/secure_seq.c

+9 −3
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
static siphash_key_t net_secret __read_mostly;

static siphash_key_t ts_secret __read_mostly;



#define EPHEMERAL_PORT_SHUFFLE_PERIOD (10 * HZ)



static __always_inline void net_secret_init(void)

{

	net_get_random_once(&net_secret, sizeof(net_secret));
@@ -101,11 +103,13 @@ u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr, 
	const struct {

		struct in6_addr saddr;

		struct in6_addr daddr;

		unsigned int timeseed;

		__be16 dport;

	} __aligned(SIPHASH_ALIGNMENT) combined = {

		.saddr = *(struct in6_addr *)saddr,

		.daddr = *(struct in6_addr *)daddr,

		.dport = dport

		.timeseed = jiffies / EPHEMERAL_PORT_SHUFFLE_PERIOD,

		.dport = dport,

	};

	net_secret_init();

	return siphash(&combined, offsetofend(typeof(combined), dport),
@@ -146,8 +150,10 @@ EXPORT_SYMBOL_GPL(secure_tcp_seq); 
u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)

{

	net_secret_init();

	return siphash_3u32((__force u32)saddr, (__force u32)daddr,

			    (__force u16)dport, &net_secret);

	return siphash_4u32((__force u32)saddr, (__force u32)daddr,

			    (__force u16)dport,

			    jiffies / EPHEMERAL_PORT_SHUFFLE_PERIOD,

			    &net_secret);

}

EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);

#endif