diff mbox

[net-next] tcp: fastopen: limit max_qlen

Message ID 1445372260.22974.38.camel@edumazet-glaptop2.roam.corp.google.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Eric Dumazet Oct. 20, 2015, 8:17 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

Allowing an application to set whatever limit for
the list of recently RST fastopen sessions [1] is not wise,
as it open ways to deplete kernel memory.

Cap the user provided limit by somaxconn sysctl,
like listen() backlog.

[1] https://tools.ietf.org/html/rfc7413#section-5.1

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/linux/tcp.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)



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Comments

David Miller Oct. 22, 2015, 1:22 p.m. UTC | #1 
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 20 Oct 2015 13:17:40 -0700

> From: Eric Dumazet <edumazet@google.com>
> 
> Allowing an application to set whatever limit for
> the list of recently RST fastopen sessions [1] is not wise,
> as it open ways to deplete kernel memory.
> 
> Cap the user provided limit by somaxconn sysctl,
> like listen() backlog.
> 
> [1] https://tools.ietf.org/html/rfc7413#section-5.1
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied, thanks Eric.
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diff mbox

Patch

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 86a7edaa6797..80ba0f7c0518 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -385,8 +385,9 @@  static inline bool tcp_passive_fastopen(const struct sock *sk)
 static inline void fastopen_queue_tune(struct sock *sk, int backlog)
 {
 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
+	int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);
 
-	queue->fastopenq.max_qlen = backlog;
+	queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn);
 }
 
 static inline void tcp_saved_syn_free(struct tcp_sock *tp)