From: Willy Tarreau <w@1wt.eu>
To: netdev@vger.kernel.org
Cc: David Miller <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Moshe Kol <moshe.kol@mail.huji.ac.il>,
Yossi Gilad <yossi.gilad@mail.huji.ac.il>,
Amit Klein <aksecurity@gmail.com>,
"Jason A . Donenfeld" <Jason@zx2c4.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 net 3/7] tcp: resalt the secret every 10 seconds
Date: Thu, 28 Apr 2022 14:39:57 +0200 [thread overview]
Message-ID: <20220428124001.7428-4-w@1wt.eu> (raw)
In-Reply-To: <20220428124001.7428-1-w@1wt.eu>
From: Eric Dumazet <edumazet@google.com>
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>
Tested-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
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..2c76aab20403 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));
@@ -101,10 +103,12 @@ u64 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
struct in6_addr saddr;
struct in6_addr daddr;
__be16 dport;
+ unsigned int timeseed;
} __aligned(SIPHASH_ALIGNMENT) combined = {
.saddr = *(struct in6_addr *)saddr,
.daddr = *(struct in6_addr *)daddr,
- .dport = dport
+ .dport = dport,
+ .timeseed = jiffies / EPHEMERAL_PORT_SHUFFLE_PERIOD,
};
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
--
2.17.5
next prev parent reply other threads:[~2022-04-28 12:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-28 12:39 [PATCH v2 net 0/7] insufficient TCP source port randomness Willy Tarreau
2022-04-28 12:39 ` [PATCH v2 net 1/7] secure_seq: use the 64 bits of the siphash for port offset calculation Willy Tarreau
2022-04-29 14:38 ` Jason A. Donenfeld
2022-04-28 12:39 ` [PATCH v2 net 2/7] tcp: use different parts of the port_offset for index and offset Willy Tarreau
2022-04-28 12:39 ` Willy Tarreau [this message]
2022-04-29 14:37 ` [PATCH v2 net 3/7] tcp: resalt the secret every 10 seconds Jason A. Donenfeld
2022-04-29 15:29 ` Willy Tarreau
2022-04-29 14:48 ` Jason A. Donenfeld
2022-04-29 15:30 ` Willy Tarreau
2022-04-28 12:39 ` [PATCH v2 net 4/7] tcp: add small random increments to the source port Willy Tarreau
2022-04-28 12:39 ` [PATCH v2 net 5/7] tcp: dynamically allocate the perturb table used by source ports Willy Tarreau
2022-04-28 12:40 ` [PATCH v2 net 6/7] tcp: increase source port perturb table to 2^16 Willy Tarreau
2022-04-28 12:40 ` [PATCH v2 net 7/7] tcp: drop the hash_32() part from the index calculation Willy Tarreau
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