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authorSoheil Hassas Yeganeh <soheil@google.com>2016-07-29 09:34:02 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-08-16 09:29:03 +0200
commitd92f45a046e909bfb8b292b2f7d56ccbedf48d55 (patch)
parent8e22cf2218d26d168f0d7ccf550512dfe8c4c6a5 (diff)
tcp: consider recv buf for the initial window scale
[ Upstream commit f626300a3e776ccc9671b0dd94698fb3aa315966 ] tcp_select_initial_window() intends to advertise a window scaling for the maximum possible window size. To do so, it considers the maximum of net.ipv4.tcp_rmem[2] and net.core.rmem_max as the only possible upper-bounds. However, users with CAP_NET_ADMIN can use SO_RCVBUFFORCE to set the socket's receive buffer size to values larger than net.ipv4.tcp_rmem[2] and net.core.rmem_max. Thus, SO_RCVBUFFORCE is effectively ignored by tcp_select_initial_window(). To fix this, consider the maximum of net.ipv4.tcp_rmem[2], net.core.rmem_max and socket's initial buffer space. Fixes: b0573dea1fb3 ("[NET]: Introduce SO_{SND,RCV}BUFFORCE socket options") Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Suggested-by: Neal Cardwell <ncardwell@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a68cd7100349..99d89783d1e6 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -242,7 +242,8 @@ void tcp_select_initial_window(int __space, __u32 mss,
/* Set window scaling on max possible window
* See RFC1323 for an explanation of the limit to 14
- space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max);
+ space = max_t(u32, space, sysctl_tcp_rmem[2]);
+ space = max_t(u32, space, sysctl_rmem_max);
space = min_t(u32, space, *window_clamp);
while (space > 65535 && (*rcv_wscale) < 14) {
space >>= 1;