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Date: Mon, 9 Dec 2013 10:28:25 +0800
From: Wang Weidong <wangweidong1@...wei.com>
To: Vlad Yasevich <vyasevich@...il.com>, <nhorman@...driver.com>,
<davem@...emloft.net>
CC: <dborkman@...hat.com>, <netdev@...r.kernel.org>,
<linux-sctp@...r.kernel.org>
Subject: Re: [PATCH v5 1/2] sctp: check the rto_min and rto_max
On 2013/12/9 10:19, Vlad Yasevich wrote:
> On 12/08/2013 08:53 PM, Wang Weidong wrote:
>> On 2013/12/8 2:54, Vlad Yasevich wrote:
>>> On 12/07/2013 02:17 AM, Wang Weidong wrote:
>>>> rto_min should be smaller than rto_max while rto_max should be larger
>>>> than rto_min. Add two proc_handler for the checking. Add the check in
>>>> sctp_setsockopt_rtoinfo.
>>>>
>>>> Suggested-by: Vlad Yasevich <vyasevich@...il.com>
>>>> Signed-off-by: Wang Weidong <wangweidong1@...wei.com>
>>>> ---
>>>> include/net/sctp/constants.h | 3 ++
>>>> net/sctp/socket.c | 5 +++
>>>> net/sctp/sysctl.c | 73 ++++++++++++++++++++++++++++++++++++++++----
>>>> 3 files changed, 75 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/include/net/sctp/constants.h b/include/net/sctp/constants.h
>>>> index 2f0a565..d276978 100644
>>>> --- a/include/net/sctp/constants.h
>>>> +++ b/include/net/sctp/constants.h
>>>> @@ -279,6 +279,9 @@ enum { SCTP_MAX_GABS = 16 };
>>>> #define SCTP_RTO_ALPHA 3 /* 1/8 when converted to right shifts. */
>>>> #define SCTP_RTO_BETA 2 /* 1/4 when converted to right shifts. */
>>>>
>>>> +#define SCTP_ONE 1 /* 1 ms */
>>>> +#define SCTP_TIMER_MAX 86400000 /* ms in one day */
>>>> +
>>>> /* Maximum number of new data packets that can be sent in a burst. */
>>>> #define SCTP_DEFAULT_MAX_BURST 4
>>>>
>>>> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
>>>> index 72046b9..13411ad 100644
>>>> --- a/net/sctp/socket.c
>>>> +++ b/net/sctp/socket.c
>>>> @@ -2818,6 +2818,11 @@ static int sctp_setsockopt_rtoinfo(struct sock *sk, char __user *optval, unsigne
>>>> if (copy_from_user(&rtoinfo, optval, optlen))
>>>> return -EFAULT;
>>>>
>>>> + if (rtoinfo.srto_min < SCTP_ONE ||
>>>> + rtoinfo.srto_max > SCTP_TIMER_MAX ||
>>>> + rtoinfo.srto_max < rtoinfo.srto_min)
>>>> + return -EINVAL;
>>>> +
>>>
>>> You can not do the check for srto_min < 1. The following is the text
>>> from the spec:
>>> All times are given in milliseconds. A value of 0, when modifying
>>> the parameters, indicates that the current value should not be
>>> changed.
>>>
>> Yes, Your are right, I found it in draft-ietf-tsvwg-sctpsocket-14.txt.
>> Thanks.
>>
>>> So, it is valid for a user to pass in a value of 0. Also, I am not sure
>>> if it makes sense to bind the upper limit here, as well.
>>>
>>> -vlad
>>>
>> Here, I am not sure as well. I think it should like what we do to the
>> init_net.sctp.rto_max when set larger than timer_max. Just not change the value.
>>
>
> So, the basic reason that sysctl is limited is that it is a default
> for all sctp association on the system. It makes some sense to limit
> what the max value here could be. Limiting it to double suggested
> RTO.MAX would only make it 2 minutes and may be insufficient for some
> of the high latency low-throughput wireless links. Making it about an
> hour should be fine... This would be a separate patch though...
>
Here, you mean that we should use 3600*1000 rather than 86400000? So
we should use another patch to fix that after my patchs?
> Limiting the user-supplied value is not as appropriate since the
> assumption is that user application may know better what it's
> requirements are and it is not up to the stack to limit those. As
> long as the user value is withing the usable range (and the kernel
> will already knows how and does limit this range), we should not
> limit this further.
>
> -vlad
>
Agree, So I should check like this:
!srto_min || !srto_max || srto_min > srto_max ?
And no need to add macros for checking.
Thanks.
>>
>> Regards.
>> Wang
>>
>>>> asoc = sctp_id2assoc(sk, rtoinfo.srto_assoc_id);
>>>>
>>>> /* Set the values to the specific association */
>>>> diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
>>>> index 6b36561..33c56c6 100644
>>>> --- a/net/sctp/sysctl.c
>>>> +++ b/net/sctp/sysctl.c
>>>> @@ -40,8 +40,8 @@
>>>> #include <linux/sysctl.h>
>>>>
>>>> static int zero = 0;
>>>> -static int one = 1;
>>>> -static int timer_max = 86400000; /* ms in one day */
>>>> +static int one = SCTP_ONE;
>>>> +static int timer_max = SCTP_TIMER_MAX;
>>>> static int int_max = INT_MAX;
>>>> static int sack_timer_min = 1;
>>>> static int sack_timer_max = 500;
>>>> @@ -61,6 +61,13 @@ static int proc_sctp_do_hmac_alg(struct ctl_table *ctl,
>>>> void __user *buffer, size_t *lenp,
>>>>
>>>> loff_t *ppos);
>>>> +static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write,
>>>> + void __user *buffer, size_t *lenp,
>>>> + loff_t *ppos);
>>>> +static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write,
>>>> + void __user *buffer, size_t *lenp,
>>>> + loff_t *ppos);
>>>> +
>>>> static struct ctl_table sctp_table[] = {
>>>> {
>>>> .procname = "sctp_mem",
>>>> @@ -102,17 +109,17 @@ static struct ctl_table sctp_net_table[] = {
>>>> .data = &init_net.sctp.rto_min,
>>>> .maxlen = sizeof(unsigned int),
>>>> .mode = 0644,
>>>> - .proc_handler = proc_dointvec_minmax,
>>>> + .proc_handler = proc_sctp_do_rto_min,
>>>> .extra1 = &one,
>>>> - .extra2 = &timer_max
>>>> + .extra2 = &init_net.sctp.rto_max
>>>> },
>>>> {
>>>> .procname = "rto_max",
>>>> .data = &init_net.sctp.rto_max,
>>>> .maxlen = sizeof(unsigned int),
>>>> .mode = 0644,
>>>> - .proc_handler = proc_dointvec_minmax,
>>>> - .extra1 = &one,
>>>> + .proc_handler = proc_sctp_do_rto_max,
>>>> + .extra1 = &init_net.sctp.rto_min,
>>>> .extra2 = &timer_max
>>>> },
>>>> {
>>>> @@ -342,6 +349,60 @@ static int proc_sctp_do_hmac_alg(struct ctl_table *ctl,
>>>> return ret;
>>>> }
>>>>
>>>> +static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write,
>>>> + void __user*buffer, size_t *lenp,
>>>> + loff_t *ppos)
>>>> +{
>>>> + struct net *net = current->nsproxy->net_ns;
>>>> + int new_value;
>>>> + struct ctl_table tbl;
>>>> + unsigned int min = *(unsigned int *) ctl->extra1;
>>>> + unsigned int max = *(unsigned int *) ctl->extra2;
>>>> + int ret;
>>>> +
>>>> + memset(&tbl, 0, sizeof(struct ctl_table));
>>>> + tbl.maxlen = sizeof(unsigned int);
>>>> +
>>>> + if (write)
>>>> + tbl.data = &new_value;
>>>> + else
>>>> + tbl.data = &net->sctp.rto_min;
>>>> + ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
>>>> + if (write) {
>>>> + if (ret || new_value > max || new_value < min)
>>>> + return -EINVAL;
>>>> + net->sctp.rto_min = new_value;
>>>> + }
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write,
>>>> + void __user*buffer, size_t *lenp,
>>>> + loff_t *ppos)
>>>> +{
>>>> + struct net *net = current->nsproxy->net_ns;
>>>> + int new_value;
>>>> + struct ctl_table tbl;
>>>> + unsigned int min = *(unsigned int *) ctl->extra1;
>>>> + unsigned int max = *(unsigned int *) ctl->extra2;
>>>> + int ret;
>>>> +
>>>> + memset(&tbl, 0, sizeof(struct ctl_table));
>>>> + tbl.maxlen = sizeof(unsigned int);
>>>> +
>>>> + if (write)
>>>> + tbl.data = &new_value;
>>>> + else
>>>> + tbl.data = &net->sctp.rto_max;
>>>> + ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
>>>> + if (write) {
>>>> + if (ret || new_value > max || new_value < min)
>>>> + return -EINVAL;
>>>> + net->sctp.rto_max = new_value;
>>>> + }
>>>> + return ret;
>>>> +}
>>>> +
>>>> int sctp_sysctl_net_register(struct net *net)
>>>> {
>>>> struct ctl_table *table;
>>>>
>>>
>>> --
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>>>
>>
>>
>
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