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Date: Mon, 16 May 2022 21:36:37 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Moshe Kol <moshe.kol@...l.huji.ac.il>, Yossi Gilad <yossi.gilad@...l.huji.ac.il>, Amit Klein <aksecurity@...il.com>, "Jason A. Donenfeld" <Jason@...c4.com>, Willy Tarreau <w@....eu>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 5.17 063/114] tcp: resalt the secret every 10 seconds From: Eric Dumazet <edumazet@...gle.com> [ 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@...l.huji.ac.il> Cc: Yossi Gilad <yossi.gilad@...l.huji.ac.il> Cc: Amit Klein <aksecurity@...il.com> Cc: Jason A. Donenfeld <Jason@...c4.com> Tested-by: Willy Tarreau <w@....eu> Signed-off-by: Eric Dumazet <edumazet@...gle.com> Signed-off-by: Jakub Kicinski <kuba@...nel.org> Signed-off-by: Sasha Levin <sashal@...nel.org> --- net/core/secure_seq.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/core/secure_seq.c b/net/core/secure_seq.c index 55aa5cc258e3..5f85e01d4093 100644 --- a/net/core/secure_seq.c +++ b/net/core/secure_seq.c @@ -22,6 +22,8 @@ static siphash_aligned_key_t net_secret; static siphash_aligned_key_t ts_secret; +#define EPHEMERAL_PORT_SHUFFLE_PERIOD (10 * HZ) + static __always_inline void net_secret_init(void) { net_get_random_once(&net_secret, sizeof(net_secret)); @@ -100,11 +102,13 @@ u64 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), @@ -145,8 +149,10 @@ EXPORT_SYMBOL_GPL(secure_tcp_seq); u64 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 -- 2.35.1
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