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authorEric Dumazet <edumazet@google.com>2023-10-20 12:57:46 +0000
committerDavid S. Miller <davem@davemloft.net>2023-10-23 09:35:01 +0100
commitaf7721448a609d1912b57c825194ef6e17fc71a4 (patch)
treec202fc0e94d15dcc834e0444c7d53a4cfe4a1f2d /include/net/tcp.h
parent3d44de9a10ea2b1658dfaed8ea6d3d7b6e0defbb (diff)
tcp: introduce TCP_PAWS_WRAP
tcp_paws_check() uses TCP_PAWS_24DAYS constant to detect if TCP TS values might have wrapped after a long idle period. This mechanism is described in RFC 7323 5.5 (Outdated Timestamps) TCP_PAWS_24DAYS value was based on the assumption of a clock of 1 Khz. As we want to adopt a 1 Mhz clock in the future, we reduce this constant. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/tcp.h')
-rw-r--r--include/net/tcp.h9
1 files changed, 7 insertions, 2 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index af72c1dc37f3..0ab577869d7a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -166,7 +166,12 @@ static_assert((1 << ATO_BITS) > TCP_DELACK_MAX);
#define MAX_TCP_KEEPCNT 127
#define MAX_TCP_SYNCNT 127
-#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
+/* Ensure that TCP PAWS checks are relaxed after ~2147 seconds
+ * to avoid overflows. This assumes a clock smaller than 1 Mhz.
+ * Default clock is 1 Khz, tcp_usec_ts uses 1 Mhz.
+ */
+#define TCP_PAWS_WRAP (INT_MAX / USEC_PER_SEC)
+
#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
* after this time. It should be equal
* (or greater than) TCP_TIMEWAIT_LEN
@@ -1619,7 +1624,7 @@ static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
return true;
if (unlikely(!time_before32(ktime_get_seconds(),
- rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)))
+ rx_opt->ts_recent_stamp + TCP_PAWS_WRAP)))
return true;
/*
* Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,