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authorRoman Gushchin <klamm@yandex-team.ru>2013-08-02 18:36:40 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-09-14 05:50:47 -0700
commitf879090a22c5a3c34ff7a60363078e28450e3005 (patch)
tree1b63cbb60ce87ff784e9c11124b42920c006abbe
parent77e9ebfd7c33f34f42761db4194961320264a482 (diff)
net: check net.core.somaxconn sysctl values
[ Upstream commit 5f671d6b4ec3e6d66c2a868738af2cdea09e7509 ] It's possible to assign an invalid value to the net.core.somaxconn sysctl variable, because there is no checks at all. The sk_max_ack_backlog field of the sock structure is defined as unsigned short. Therefore, the backlog argument in inet_listen() shouldn't exceed USHRT_MAX. The backlog argument in the listen() syscall is truncated to the somaxconn value. So, the somaxconn value shouldn't exceed 65535 (USHRT_MAX). Also, negative values of somaxconn are meaningless. before: $ sysctl -w net.core.somaxconn=256 net.core.somaxconn = 256 $ sysctl -w net.core.somaxconn=65536 net.core.somaxconn = 65536 $ sysctl -w net.core.somaxconn=-100 net.core.somaxconn = -100 after: $ sysctl -w net.core.somaxconn=256 net.core.somaxconn = 256 $ sysctl -w net.core.somaxconn=65536 error: "Invalid argument" setting key "net.core.somaxconn" $ sysctl -w net.core.somaxconn=-100 error: "Invalid argument" setting key "net.core.somaxconn" Based on a prior patch from Changli Gao. Signed-off-by: Roman Gushchin <klamm@yandex-team.ru> Reported-by: Changli Gao <xiaosuo@gmail.com> Suggested-by: Eric Dumazet <edumazet@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/core/sysctl_net_core.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 77a65f031488..f0bdd36f207e 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -19,6 +19,9 @@
#include <net/sock.h>
#include <net/net_ratelimit.h>
+static int zero = 0;
+static int ushort_max = USHRT_MAX;
+
#ifdef CONFIG_RPS
static int rps_sock_flow_sysctl(ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -192,7 +195,9 @@ static struct ctl_table netns_core_table[] = {
.data = &init_net.core.sysctl_somaxconn,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .extra1 = &zero,
+ .extra2 = &ushort_max,
+ .proc_handler = proc_dointvec_minmax
},
{ }
};