From: Eric Dumazet edumazet@google.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@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: Willy Tarreau w@1wt.eu Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.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 7232274de334..17683aea8a35 100644 --- a/net/core/secure_seq.c +++ b/net/core/secure_seq.c @@ -22,6 +22,8 @@ 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)); @@ -100,11 +102,13 @@ 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), @@ -144,8 +148,10 @@ u32 secure_tcp_seq(__be32 saddr, __be32 daddr, 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