Messages in this thread Patch in this message | | | Date | Thu, 01 Aug 2013 13:04:16 +0400 | From | Roman Gushchin <> | Subject | Re: [PATCH] net: check net.core.somaxconn sysctl values |
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On 01.08.2013 04:10, David Miller wrote: > From: Roman Gushchin <klamm@yandex-team.ru> > Date: Wed, 31 Jul 2013 17:57:35 +0400 > >> --- >> net/core/sysctl_net_core.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c >> index cfdb46a..2ff093b 100644 >> --- a/net/core/sysctl_net_core.c >> +++ b/net/core/sysctl_net_core.c >> @@ -20,7 +20,9 @@ > > This patch is against old sources, please respin it against the current > tree. > > Thanks. >
net: check net.core.somaxconn sysctl values
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> --- net/core/sysctl_net_core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 6609686..7c37dcd 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -21,7 +21,9 @@ #include <net/net_ratelimit.h> #include <net/busy_poll.h>
+static int zero = 0; static int one = 1; +static int ushort_max = USHRT_MAX;
#ifdef CONFIG_RPS static int rps_sock_flow_sysctl(struct ctl_table *table, int write, @@ -339,7 +341,9 @@ 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 }, { } }; -- 1.8.1.2
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