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Date: Mon, 9 Dec 2013 11:28:44 +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 10:40, Vlad Yasevich wrote:
> On 12/08/2013 09:28 PM, Wang Weidong wrote:
>> 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.
>
> No, I think this would have to be a little more complicated :(
> Remember it's ok to have srto_min == 0 and srto_max == 0. It just
> means that no change happens.
>
> You may need to do something like
>
> unsigned long rto_max, rto_min;
>
> if (rtoinfo.srto_max)
> rto_max = msecs_to_jiffies(rtoinfo.srto_max);
> else
> rto_max = asoc ? asoc->rto_max : sp->rto_max;
>
> if (rtoinfo.srto_min)
> rto_min = msecs_to_jiffies(rtoinfo.srto_min);
> else
> rto_min = asoc ? asoc->rto_min : sp->rto_min;
>
> if (rto_min > rto_max)
> return -EINVAL;
>
> if (asoc) {
> asoc->rto_min = rto_min;
> asoc->rto_max = rto_max;
> ...
> etc....
>
> This way we make sure that the user that supplied just rto_min or just
> rto_max didn't set them so that min > max.
>
> -vlad
Hi vald,
I found that we had checked the value of 0 in sctp_setsockopt_rtoinfo.
So I only do this:
if (asoc) {
+ if (msecs_to_jiffies(rtoinfo.srto_min) >
+ msecs_to_jiffies(rtoinfo.srto_max))
+ return -EINVAL;
...
} else {
...
+ if (rtoinfo.srto_min > rtoinfo.srto_max)
+ return -EINVAL;
...
}
There because we set value to asoc and sp is not same. So I add the
check into two path.
Regards.
Wang
>>
>> 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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>>
>>
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