diff options
3 files changed, 199 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 | |||
diff --git a/recipes-kernel/linux/files/CVE-2016-5696-make-challenge-acks-less-predictable.patch b/recipes-kernel/linux/files/CVE-2016-5696-make-challenge-acks-less-predictable.patch new file mode 100644 index 0000000..fe67b3b --- /dev/null +++ b/recipes-kernel/linux/files/CVE-2016-5696-make-challenge-acks-less-predictable.patch | |||
@@ -0,0 +1,88 @@ | |||
1 | From 72c2d3bccaba4a0a4de354f9d2d24eccd05bfccf Mon Sep 17 00:00:00 2001 | ||
2 | From: Eric Dumazet <edumazet@google.com> | ||
3 | Date: Sun, 10 Jul 2016 10:04:02 +0200 | ||
4 | Subject: [PATCH] tcp: make challenge acks less predictable | ||
5 | |||
6 | [ Upstream commit 75ff39ccc1bd5d3c455b6822ab09e533c551f758 ] | ||
7 | |||
8 | Yue Cao claims that current host rate limiting of challenge ACKS | ||
9 | (RFC 5961) could leak enough information to allow a patient attacker | ||
10 | to hijack TCP sessions. He will soon provide details in an academic | ||
11 | paper. | ||
12 | |||
13 | This patch increases the default limit from 100 to 1000, and adds | ||
14 | some randomization so that the attacker can no longer hijack | ||
15 | sessions without spending a considerable amount of probes. | ||
16 | |||
17 | Based on initial analysis and patch from Linus. | ||
18 | |||
19 | Note that we also have per socket rate limiting, so it is tempting | ||
20 | to remove the host limit in the future. | ||
21 | |||
22 | v2: randomize the count of challenge acks per second, not the period. | ||
23 | |||
24 | CVE: CVE-2016-5696 | ||
25 | Upstream-Status: Backport | ||
26 | |||
27 | Fixes: 282f23c6ee34 ("tcp: implement RFC 5961 3.2") | ||
28 | Reported-by: Yue Cao <ycao009@ucr.edu> | ||
29 | Signed-off-by: Eric Dumazet <edumazet@google.com> | ||
30 | Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> | ||
31 | Cc: Yuchung Cheng <ycheng@google.com> | ||
32 | Cc: Neal Cardwell <ncardwell@google.com> | ||
33 | Acked-by: Neal Cardwell <ncardwell@google.com> | ||
34 | Acked-by: Yuchung Cheng <ycheng@google.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 | 15 ++++++++++----- | ||
40 | 1 file changed, 10 insertions(+), 5 deletions(-) | ||
41 | |||
42 | diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c | ||
43 | index d4c5115..05f10df 100644 | ||
44 | --- a/net/ipv4/tcp_input.c | ||
45 | +++ b/net/ipv4/tcp_input.c | ||
46 | @@ -89,7 +89,7 @@ int sysctl_tcp_adv_win_scale __read_mostly = 1; | ||
47 | EXPORT_SYMBOL(sysctl_tcp_adv_win_scale); | ||
48 | |||
49 | /* rfc5961 challenge ack rate limiting */ | ||
50 | -int sysctl_tcp_challenge_ack_limit = 100; | ||
51 | +int sysctl_tcp_challenge_ack_limit = 1000; | ||
52 | |||
53 | int sysctl_tcp_stdurg __read_mostly; | ||
54 | int sysctl_tcp_rfc1337 __read_mostly; | ||
55 | @@ -3427,7 +3427,7 @@ static void tcp_send_challenge_ack(struct sock *sk, const struct sk_buff *skb) | ||
56 | static u32 challenge_timestamp; | ||
57 | static unsigned int challenge_count; | ||
58 | struct tcp_sock *tp = tcp_sk(sk); | ||
59 | - u32 now; | ||
60 | + u32 count, now; | ||
61 | |||
62 | /* First check our per-socket dupack rate limit. */ | ||
63 | if (tcp_oow_rate_limited(sock_net(sk), skb, | ||
64 | @@ -3435,13 +3435,18 @@ static void tcp_send_challenge_ack(struct sock *sk, const struct sk_buff *skb) | ||
65 | &tp->last_oow_ack_time)) | ||
66 | return; | ||
67 | |||
68 | - /* Then check the check host-wide RFC 5961 rate limit. */ | ||
69 | + /* Then check host-wide RFC 5961 rate limit. */ | ||
70 | now = jiffies / HZ; | ||
71 | if (now != challenge_timestamp) { | ||
72 | + u32 half = (sysctl_tcp_challenge_ack_limit + 1) >> 1; | ||
73 | + | ||
74 | challenge_timestamp = now; | ||
75 | - challenge_count = 0; | ||
76 | + WRITE_ONCE(challenge_count, half + | ||
77 | + prandom_u32_max(sysctl_tcp_challenge_ack_limit)); | ||
78 | } | ||
79 | - if (++challenge_count <= sysctl_tcp_challenge_ack_limit) { | ||
80 | + count = READ_ONCE(challenge_count); | ||
81 | + if (count > 0) { | ||
82 | + WRITE_ONCE(challenge_count, count - 1); | ||
83 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPCHALLENGEACK); | ||
84 | tcp_send_ack(sk); | ||
85 | } | ||
86 | -- | ||
87 | 1.9.1 | ||
88 | |||
diff --git a/recipes-kernel/linux/linux-yocto_4.%.bbappend b/recipes-kernel/linux/linux-yocto_4.%.bbappend index 2ae6b4b..d0c4e98 100644 --- a/recipes-kernel/linux/linux-yocto_4.%.bbappend +++ b/recipes-kernel/linux/linux-yocto_4.%.bbappend | |||
@@ -3,6 +3,8 @@ require recipes-kernel/linux/enea-common.inc | |||
3 | FILESEXTRAPATHS_prepend := "${THISDIR}/files:" | 3 | FILESEXTRAPATHS_prepend := "${THISDIR}/files:" |
4 | 4 | ||
5 | SRC_URI += "file://hid-CVE-2016-5829.patch \ | 5 | SRC_URI += "file://hid-CVE-2016-5829.patch \ |
6 | file://CVE-2016-5696-limiting-of-all-challenge.patch \ | ||
7 | file://CVE-2016-5696-make-challenge-acks-less-predictable.patch \ | ||
6 | " | 8 | " |
7 | 9 | ||
8 | ENEA_KERNEL_FRAGMENTS += "\ | 10 | ENEA_KERNEL_FRAGMENTS += "\ |