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authorDavid S. Miller <davem@davemloft.net>2016-07-23 19:31:37 -0400
committerDavid S. Miller <davem@davemloft.net>2016-07-24 00:53:32 -0400
commitde0ba9a0d8909996f9e293d311c2cc459fa77d67 (patch)
tree199214afc477824bf431d11d08834ff7555c994b /net/ipv4/tcp_input.c
parentd95a93a9b71677a43f967a1b7986decab84b7765 (diff)
parent107df03203bb66de56e2caec3bde6d22b55480c5 (diff)
downloadlinux-stericsson-de0ba9a0d8909996f9e293d311c2cc459fa77d67.tar.gz
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Just several instances of overlapping changes. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c54
1 files changed, 32 insertions, 22 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 94d4aff97523..f9f9e375d7de 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -87,7 +87,7 @@ int sysctl_tcp_adv_win_scale __read_mostly = 1;
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;
@@ -3424,6 +3424,23 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32
return flag;
}
+static bool __tcp_oow_rate_limited(struct net *net, int mib_idx,
+ u32 *last_oow_ack_time)
+{
+ if (*last_oow_ack_time) {
+ s32 elapsed = (s32)(tcp_time_stamp - *last_oow_ack_time);
+
+ if (0 <= elapsed && elapsed < sysctl_tcp_invalid_ratelimit) {
+ NET_INC_STATS(net, mib_idx);
+ return true; /* rate-limited: don't send yet! */
+ }
+ }
+
+ *last_oow_ack_time = tcp_time_stamp;
+
+ return false; /* not rate-limited: go ahead, send dupack now! */
+}
+
/* Return true if we're currently rate-limiting out-of-window ACKs and
* thus shouldn't send a dupack right now. We rate-limit dupacks in
* response to out-of-window SYNs or ACKs to mitigate ACK loops or DoS
@@ -3437,21 +3454,9 @@ bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
/* Data packets without SYNs are not likely part of an ACK loop. */
if ((TCP_SKB_CB(skb)->seq != TCP_SKB_CB(skb)->end_seq) &&
!tcp_hdr(skb)->syn)
- goto not_rate_limited;
-
- if (*last_oow_ack_time) {
- s32 elapsed = (s32)(tcp_time_stamp - *last_oow_ack_time);
-
- if (0 <= elapsed && elapsed < sysctl_tcp_invalid_ratelimit) {
- NET_INC_STATS(net, mib_idx);
- return true; /* rate-limited: don't send yet! */
- }
- }
-
- *last_oow_ack_time = tcp_time_stamp;
+ return false;
-not_rate_limited:
- return false; /* not rate-limited: go ahead, send dupack now! */
+ return __tcp_oow_rate_limited(net, mib_idx, last_oow_ack_time);
}
/* RFC 5961 7 [ACK Throttling] */
@@ -3461,21 +3466,26 @@ static void tcp_send_challenge_ack(struct sock *sk, const struct sk_buff *skb)
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,
- LINUX_MIB_TCPACKSKIPPEDCHALLENGE,
- &tp->last_oow_ack_time))
+ if (__tcp_oow_rate_limited(sock_net(sk),
+ LINUX_MIB_TCPACKSKIPPEDCHALLENGE,
+ &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(sock_net(sk), LINUX_MIB_TCPCHALLENGEACK);
tcp_send_ack(sk);
}