[PATCH] net: check net.core.somaxconn sysctl values

[PATCH] net: check net.core.somaxconn sysctl values

[Roman Gushchin]

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"

Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
---
  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 @@
  #include <net/sock.h>
  #include <net/net_ratelimit.h>

+static int zero = 0;
  static int one = 1;
+static int ushort_max = USHRT_MAX;

  #ifdef CONFIG_RPS
  static int rps_sock_flow_sysctl(ctl_table *table, int write,
@@ -204,7 +206,9 @@ 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

Re: [PATCH] net: check net.core.somaxconn sysctl values

[Eric Dumazet]

On Wed, 2013-07-31 at 17:57 +0400, Roman Gushchin wrote:
> 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"
> 
> Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
> ---
>   net/core/sysctl_net_core.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)


We had a discussion about this one month ago, as Changli Gao posted a
patch. http://patchwork.ozlabs.org/patch/255460/

So proper credits would be nice ;)

Based on a prior patch from Changli Gao

Reported-by: Changli Gao <xiaosuo@gmail.com>
Suggested-by: Eric Dumazet <edumazet@google.com>

Acked-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH] net: check net.core.somaxconn sysctl values

[Roman Gushchin]

On 31.07.2013 18:37, Eric Dumazet wrote:
> On Wed, 2013-07-31 at 17:57 +0400, Roman Gushchin wrote:
>> 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"
>>
>> Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
>> ---
>>    net/core/sysctl_net_core.c | 6 +++++-
>>    1 file changed, 5 insertions(+), 1 deletion(-)
>
>
> We had a discussion about this one month ago, as Changli Gao posted a
> patch. http://patchwork.ozlabs.org/patch/255460/
>
> So proper credits would be nice ;)

Ok :)

> Based on a prior patch from Changli Gao
>
> Reported-by: Changli Gao <xiaosuo@gmail.com>
> Suggested-by: Eric Dumazet <edumazet@google.com>
>
> Acked-by: Eric Dumazet <edumazet@google.com>
>

Thanks!

PS I've forwarded your letter back to the lkml by mistake.
Sorry)

Regards,
Roman

Re: [PATCH] net: check net.core.somaxconn sysctl values

[David Miller]

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.

Re: [PATCH] net: check net.core.somaxconn sysctl values

[Roman Gushchin]

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

Re: [PATCH] net: check net.core.somaxconn sysctl values

[David Miller]

From: Roman Gushchin <klamm@yandex-team.ru>
Date: Thu, 01 Aug 2013 13:04:16 +0400

> 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

Still doesn't apply, and it's because your email client has corrupted
the patch.

Please read Documentation/email-clients.txt to learn how to fix this
problem, and then send a test patch to yourself.

Only when you can successfully apply the test patch you send to
yourself should you repost your patch here.

Thanks.

[PATCH] net: check net.core.somaxconn sysctl values

[Roman Gushchin]

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

Re: [PATCH] net: check net.core.somaxconn sysctl values

[David Miller]

From: Roman Gushchin <klamm@yandex-team.ru>
Date: Fri,  2 Aug 2013 18:36:40 +0400

> 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>

Applied, thanks.

Re: [PATCH] net: check net.core.somaxconn sysctl values

[Roman Gushchin]

On 03.08.2013 02:19, David Miller wrote:
> From: Roman Gushchin <klamm@yandex-team.ru>
> Date: Fri,  2 Aug 2013 18:36:40 +0400
>
>> 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>
>
> Applied, thanks.

Thank you!

Regards,
Roman

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