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63 lines
2.0 KiB
Diff
63 lines
2.0 KiB
Diff
From beb39db59d14990e401e235faf66a6b9b31240b0 Mon Sep 17 00:00:00 2001
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From: Eric Dumazet <edumazet@google.com>
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Date: Sat, 30 May 2015 09:16:53 -0700
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Subject: [PATCH] udp: fix behavior of wrong checksums
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We have two problems in UDP stack related to bogus checksums :
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1) We return -EAGAIN to application even if receive queue is not empty.
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This breaks applications using edge trigger epoll()
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2) Under UDP flood, we can loop forever without yielding to other
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processes, potentially hanging the host, especially on non SMP.
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This patch is an attempt to make things better.
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We might in the future add extra support for rt applications
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wanting to better control time spent doing a recv() in a hostile
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environment. For example we could validate checksums before queuing
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packets in socket receive queue.
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Cc: Willem de Bruijn <willemb@google.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/ipv4/udp.c | 6 ++----
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net/ipv6/udp.c | 6 ++----
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2 files changed, 4 insertions(+), 8 deletions(-)
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diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
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index d10b7e0112ebd..1c92ea67baefe 100644
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--- a/net/ipv4/udp.c
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+++ b/net/ipv4/udp.c
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@@ -1345,10 +1345,8 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
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}
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unlock_sock_fast(sk, slow);
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- if (noblock)
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- return -EAGAIN;
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-
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- /* starting over for a new packet */
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+ /* starting over for a new packet, but check if we need to yield */
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+ cond_resched();
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msg->msg_flags &= ~MSG_TRUNC;
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goto try_again;
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}
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diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
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index c2ec41617a354..e51fc3eee6dbd 100644
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--- a/net/ipv6/udp.c
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+++ b/net/ipv6/udp.c
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@@ -525,10 +525,8 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
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}
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unlock_sock_fast(sk, slow);
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- if (noblock)
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- return -EAGAIN;
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-
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- /* starting over for a new packet */
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+ /* starting over for a new packet, but check if we need to yield */
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+ cond_resched();
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msg->msg_flags &= ~MSG_TRUNC;
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goto try_again;
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}
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