kernel: update kernel 4.4 to version 4.4.19

[openwrt/openwrt.git] / target / linux / generic / patches-4.4 / 096-tcp-make-challenge-acks-less-predictable.patch

diff --git a/target/linux/generic/patches-4.4/096-tcp-make-challenge-acks-less-predictable.patch b/target/linux/generic/patches-4.4/096-tcp-make-challenge-acks-less-predictable.patch
deleted file mode 100644 (file)
index a783c6e..0000000
--- a/target/linux/generic/patches-4.4/096-tcp-make-challenge-acks-less-predictable.patch
+++ /dev/null
@@ -1,76 +0,0 @@
-From 75ff39ccc1bd5d3c455b6822ab09e533c551f758 Mon Sep 17 00:00:00 2001
-From: Eric Dumazet <edumazet@google.com>
-Date: Sun, 10 Jul 2016 10:04:02 +0200
-Subject: [PATCH] tcp: make challenge acks less predictable
-
-Yue Cao claims that current host rate limiting of challenge ACKS
-(RFC 5961) could leak enough information to allow a patient attacker
-to hijack TCP sessions. He will soon provide details in an academic
-paper.
-
-This patch increases the default limit from 100 to 1000, and adds
-some randomization so that the attacker can no longer hijack
-sessions without spending a considerable amount of probes.
-
-Based on initial analysis and patch from Linus.
-
-Note that we also have per socket rate limiting, so it is tempting
-to remove the host limit in the future.
-
-v2: randomize the count of challenge acks per second, not the period.
-
-Fixes: 282f23c6ee34 ("tcp: implement RFC 5961 3.2")
-Reported-by: Yue Cao <ycao009@ucr.edu>
-Signed-off-by: Eric Dumazet <edumazet@google.com>
-Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
-Cc: Yuchung Cheng <ycheng@google.com>
-Cc: Neal Cardwell <ncardwell@google.com>
-Acked-by: Neal Cardwell <ncardwell@google.com>
-Acked-by: Yuchung Cheng <ycheng@google.com>
-Signed-off-by: David S. Miller <davem@davemloft.net>
----
- net/ipv4/tcp_input.c | 15 ++++++++++-----
- 1 file changed, 10 insertions(+), 5 deletions(-)
-
---- a/net/ipv4/tcp_input.c
-+++ b/net/ipv4/tcp_input.c
-@@ -89,7 +89,7 @@ int sysctl_tcp_adv_win_scale __read_most
- EXPORT_SYMBOL(sysctl_tcp_adv_win_scale);
- 
- /* rfc5961 challenge ack rate limiting */
--int sysctl_tcp_challenge_ack_limit = 100;
-+int sysctl_tcp_challenge_ack_limit = 1000;
- 
- int sysctl_tcp_stdurg __read_mostly;
- int sysctl_tcp_rfc1337 __read_mostly;
-@@ -3427,7 +3427,7 @@ static void tcp_send_challenge_ack(struc
-       static u32 challenge_timestamp;
-       static unsigned int challenge_count;
-       struct tcp_sock *tp = tcp_sk(sk);
--      u32 now;
-+      u32 count, now;
- 
-       /* First check our per-socket dupack rate limit. */
-       if (tcp_oow_rate_limited(sock_net(sk), skb,
-@@ -3435,13 +3435,18 @@ static void tcp_send_challenge_ack(struc
-                                &tp->last_oow_ack_time))
-               return;
- 
--      /* Then check the check host-wide RFC 5961 rate limit. */
-+      /* Then check host-wide RFC 5961 rate limit. */
-       now = jiffies / HZ;
-       if (now != challenge_timestamp) {
-+              u32 half = (sysctl_tcp_challenge_ack_limit + 1) >> 1;
-+
-               challenge_timestamp = now;
--              challenge_count = 0;
-+              WRITE_ONCE(challenge_count, half +
-+                         prandom_u32_max(sysctl_tcp_challenge_ack_limit));
-       }
--      if (++challenge_count <= sysctl_tcp_challenge_ack_limit) {
-+      count = READ_ONCE(challenge_count);
-+      if (count > 0) {
-+              WRITE_ONCE(challenge_count, count - 1);
-               NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPCHALLENGEACK);
-               tcp_send_ack(sk);
-       }