diff options
Diffstat (limited to 'recipes-kernel/linux/files/CVE-2016-5696-limiting-of-all-challenge.patch')
-rw-r--r-- | recipes-kernel/linux/files/CVE-2016-5696-limiting-of-all-challenge.patch | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/recipes-kernel/linux/files/CVE-2016-5696-limiting-of-all-challenge.patch b/recipes-kernel/linux/files/CVE-2016-5696-limiting-of-all-challenge.patch new file mode 100644 index 0000000..f2c2364 --- /dev/null +++ b/recipes-kernel/linux/files/CVE-2016-5696-limiting-of-all-challenge.patch | |||
@@ -0,0 +1,109 @@ | |||
1 | From 5413f1a526d2d51d7a5768133c90936c017165c6 Mon Sep 17 00:00:00 2001 | ||
2 | From: Jason Baron <jbaron@akamai.com> | ||
3 | Date: Thu, 14 Jul 2016 11:38:40 -0400 | ||
4 | Subject: [PATCH] tcp: enable per-socket rate limiting of all 'challenge acks' | ||
5 | |||
6 | [ Upstream commit 083ae308280d13d187512b9babe3454342a7987e ] | ||
7 | |||
8 | The per-socket rate limit for 'challenge acks' was introduced in the | ||
9 | context of limiting ack loops: | ||
10 | |||
11 | commit f2b2c582e824 ("tcp: mitigate ACK loops for connections as tcp_sock") | ||
12 | |||
13 | And I think it can be extended to rate limit all 'challenge acks' on a | ||
14 | per-socket basis. | ||
15 | |||
16 | Since we have the global tcp_challenge_ack_limit, this patch allows for | ||
17 | tcp_challenge_ack_limit to be set to a large value and effectively rely on | ||
18 | the per-socket limit, or set tcp_challenge_ack_limit to a lower value and | ||
19 | still prevents a single connections from consuming the entire challenge ack | ||
20 | quota. | ||
21 | |||
22 | It further moves in the direction of eliminating the global limit at some | ||
23 | point, as Eric Dumazet has suggested. This a follow-up to: | ||
24 | Subject: tcp: make challenge acks less predictable | ||
25 | |||
26 | CVE: CVE-2016-5696 | ||
27 | Upstream-Status: Backport | ||
28 | |||
29 | Cc: Eric Dumazet <edumazet@google.com> | ||
30 | Cc: David S. Miller <davem@davemloft.net> | ||
31 | Cc: Neal Cardwell <ncardwell@google.com> | ||
32 | Cc: Yuchung Cheng <ycheng@google.com> | ||
33 | Cc: Yue Cao <ycao009@ucr.edu> | ||
34 | Signed-off-by: Jason Baron <jbaron@akamai.com> | ||
35 | Signed-off-by: David S. Miller <davem@davemloft.net> | ||
36 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | ||
37 | Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com> | ||
38 | --- | ||
39 | net/ipv4/tcp_input.c | 39 ++++++++++++++++++++++----------------- | ||
40 | 1 file changed, 22 insertions(+), 17 deletions(-) | ||
41 | |||
42 | diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c | ||
43 | index 05f10df..12b98e2 100644 | ||
44 | --- a/net/ipv4/tcp_input.c | ||
45 | +++ b/net/ipv4/tcp_input.c | ||
46 | @@ -3390,6 +3390,23 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32 | ||
47 | return flag; | ||
48 | } | ||
49 | |||
50 | +static bool __tcp_oow_rate_limited(struct net *net, int mib_idx, | ||
51 | + u32 *last_oow_ack_time) | ||
52 | +{ | ||
53 | + if (*last_oow_ack_time) { | ||
54 | + s32 elapsed = (s32)(tcp_time_stamp - *last_oow_ack_time); | ||
55 | + | ||
56 | + if (0 <= elapsed && elapsed < sysctl_tcp_invalid_ratelimit) { | ||
57 | + NET_INC_STATS_BH(net, mib_idx); | ||
58 | + return true; /* rate-limited: don't send yet! */ | ||
59 | + } | ||
60 | + } | ||
61 | + | ||
62 | + *last_oow_ack_time = tcp_time_stamp; | ||
63 | + | ||
64 | + return false; /* not rate-limited: go ahead, send dupack now! */ | ||
65 | +} | ||
66 | + | ||
67 | /* Return true if we're currently rate-limiting out-of-window ACKs and | ||
68 | * thus shouldn't send a dupack right now. We rate-limit dupacks in | ||
69 | * response to out-of-window SYNs or ACKs to mitigate ACK loops or DoS | ||
70 | @@ -3403,21 +3420,9 @@ bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, | ||
71 | /* Data packets without SYNs are not likely part of an ACK loop. */ | ||
72 | if ((TCP_SKB_CB(skb)->seq != TCP_SKB_CB(skb)->end_seq) && | ||
73 | !tcp_hdr(skb)->syn) | ||
74 | - goto not_rate_limited; | ||
75 | - | ||
76 | - if (*last_oow_ack_time) { | ||
77 | - s32 elapsed = (s32)(tcp_time_stamp - *last_oow_ack_time); | ||
78 | - | ||
79 | - if (0 <= elapsed && elapsed < sysctl_tcp_invalid_ratelimit) { | ||
80 | - NET_INC_STATS_BH(net, mib_idx); | ||
81 | - return true; /* rate-limited: don't send yet! */ | ||
82 | - } | ||
83 | - } | ||
84 | - | ||
85 | - *last_oow_ack_time = tcp_time_stamp; | ||
86 | + return false; | ||
87 | |||
88 | -not_rate_limited: | ||
89 | - return false; /* not rate-limited: go ahead, send dupack now! */ | ||
90 | + return __tcp_oow_rate_limited(net, mib_idx, last_oow_ack_time); | ||
91 | } | ||
92 | |||
93 | /* RFC 5961 7 [ACK Throttling] */ | ||
94 | @@ -3430,9 +3435,9 @@ static void tcp_send_challenge_ack(struct sock *sk, const struct sk_buff *skb) | ||
95 | u32 count, now; | ||
96 | |||
97 | /* First check our per-socket dupack rate limit. */ | ||
98 | - if (tcp_oow_rate_limited(sock_net(sk), skb, | ||
99 | - LINUX_MIB_TCPACKSKIPPEDCHALLENGE, | ||
100 | - &tp->last_oow_ack_time)) | ||
101 | + if (__tcp_oow_rate_limited(sock_net(sk), | ||
102 | + LINUX_MIB_TCPACKSKIPPEDCHALLENGE, | ||
103 | + &tp->last_oow_ack_time)) | ||
104 | return; | ||
105 | |||
106 | /* Then check host-wide RFC 5961 rate limit. */ | ||
107 | -- | ||
108 | 1.9.1 | ||
109 | |||