[net,v2] ipvs: Improve robustness to the ipvs sysctl

From: Junwei Hu <hujunwei4@huawei.com>

The ipvs module parse the user buffer and save it to sysctl,
then check if the value is valid. invalid value occurs
over a period of time.
Here, I add a variable, struct ctl_table tmp, used to read
the value from the user buffer, and save only when it is valid.
I delete proc_do_sync_mode and use extra1/2 in table for the
proc_dointvec_minmax call.

Fixes: f73181c8288f ("ipvs: add support for sync threads")
Signed-off-by: Junwei Hu <hujunwei4@huawei.com>
---
V1->V2:
- delete proc_do_sync_mode and use proc_dointvec_minmax call.
---
 net/netfilter/ipvs/ip_vs_ctl.c | 69 +++++++++++++++++++++---------------------
 1 file changed, 35 insertions(+), 34 deletions(-)

Hello,

On Tue, 30 Jul 2019, hujunwei wrote:

> From: Junwei Hu <hujunwei4@huawei.com>
> 
> The ipvs module parse the user buffer and save it to sysctl,
> then check if the value is valid. invalid value occurs
> over a period of time.
> Here, I add a variable, struct ctl_table tmp, used to read
> the value from the user buffer, and save only when it is valid.
> I delete proc_do_sync_mode and use extra1/2 in table for the
> proc_dointvec_minmax call.
> 
> Fixes: f73181c8288f ("ipvs: add support for sync threads")
> Signed-off-by: Junwei Hu <hujunwei4@huawei.com>

	Looks good to me, thanks!

Acked-by: Julian Anastasov <ja@ssi.bg>

	BTW, why ip_vs_zero_all everywhere? Due to old git version?

> ---
> V1->V2:
> - delete proc_do_sync_mode and use proc_dointvec_minmax call.
> ---
>  net/netfilter/ipvs/ip_vs_ctl.c | 69 +++++++++++++++++++++---------------------
>  1 file changed, 35 insertions(+), 34 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 060565e..7aed7b0 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -1737,12 +1737,18 @@ static int ip_vs_zero_all(struct netns_ipvs *ipvs)
>  	int val = *valp;
>  	int rc;
> 
> -	rc = proc_dointvec(table, write, buffer, lenp, ppos);
> +	struct ctl_table tmp = {
> +		.data = &val,
> +		.maxlen = sizeof(int),
> +		.mode = table->mode,
> +	};
> +
> +	rc = proc_dointvec(&tmp, write, buffer, lenp, ppos);
>  	if (write && (*valp != val)) {
> -		if ((*valp < 0) || (*valp > 3)) {
> -			/* Restore the correct value */
> +		if (val < 0 || val > 3) {
> +			rc = -EINVAL;
> +		} else {
>  			*valp = val;
> -		} else {
>  			update_defense_level(ipvs);
>  		}
>  	}
> @@ -1756,33 +1762,20 @@ static int ip_vs_zero_all(struct netns_ipvs *ipvs)
>  	int *valp = table->data;
>  	int val[2];
>  	int rc;
> +	struct ctl_table tmp = {
> +		.data = &val,
> +		.maxlen = table->maxlen,
> +		.mode = table->mode,
> +	};
> 
> -	/* backup the value first */
>  	memcpy(val, valp, sizeof(val));
> -
> -	rc = proc_dointvec(table, write, buffer, lenp, ppos);
> -	if (write && (valp[0] < 0 || valp[1] < 0 ||
> -	    (valp[0] >= valp[1] && valp[1]))) {
> -		/* Restore the correct value */
> -		memcpy(valp, val, sizeof(val));
> -	}
> -	return rc;
> -}
> -
> -static int
> -proc_do_sync_mode(struct ctl_table *table, int write,
> -		     void __user *buffer, size_t *lenp, loff_t *ppos)
> -{
> -	int *valp = table->data;
> -	int val = *valp;
> -	int rc;
> -
> -	rc = proc_dointvec(table, write, buffer, lenp, ppos);
> -	if (write && (*valp != val)) {
> -		if ((*valp < 0) || (*valp > 1)) {
> -			/* Restore the correct value */
> -			*valp = val;
> -		}
> +	rc = proc_dointvec(&tmp, write, buffer, lenp, ppos);
> +	if (write) {
> +		if (val[0] < 0 || val[1] < 0 ||
> +		    (val[0] >= val[1] && val[1]))
> +			rc = -EINVAL;
> +		else
> +			memcpy(valp, val, sizeof(val));
>  	}
>  	return rc;
>  }
> @@ -1795,12 +1788,18 @@ static int ip_vs_zero_all(struct netns_ipvs *ipvs)
>  	int val = *valp;
>  	int rc;
> 
> -	rc = proc_dointvec(table, write, buffer, lenp, ppos);
> +	struct ctl_table tmp = {
> +		.data = &val,
> +		.maxlen = sizeof(int),
> +		.mode = table->mode,
> +	};
> +
> +	rc = proc_dointvec(&tmp, write, buffer, lenp, ppos);
>  	if (write && (*valp != val)) {
> -		if (*valp < 1 || !is_power_of_2(*valp)) {
> -			/* Restore the correct value */
> +		if (val < 1 || !is_power_of_2(val))
> +			rc = -EINVAL;
> +		else
>  			*valp = val;
> -		}
>  	}
>  	return rc;
>  }
> @@ -1860,7 +1859,9 @@ static int ip_vs_zero_all(struct netns_ipvs *ipvs)
>  		.procname	= "sync_version",
>  		.maxlen		= sizeof(int),
>  		.mode		= 0644,
> -		.proc_handler	= proc_do_sync_mode,
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= SYSCTL_ZERO,
> +		.extra2		= SYSCTL_ONE,
>  	},
>  	{
>  		.procname	= "sync_ports",
> -- 
> 1.7.12.4

Regards

--
Julian Anastasov <ja@ssi.bg>

Hello, Julian

On 2019/7/31 3:29, Julian Anastasov wrote:
> 
> 	Hello,
> 
> On Tue, 30 Jul 2019, hujunwei wrote:
> 
>> From: Junwei Hu <hujunwei4@huawei.com>
>>
>> The ipvs module parse the user buffer and save it to sysctl,
>> then check if the value is valid. invalid value occurs
>> over a period of time.
>> Here, I add a variable, struct ctl_table tmp, used to read
>> the value from the user buffer, and save only when it is valid.
>> I delete proc_do_sync_mode and use extra1/2 in table for the
>> proc_dointvec_minmax call.
>>
>> Fixes: f73181c8288f ("ipvs: add support for sync threads")
>> Signed-off-by: Junwei Hu <hujunwei4@huawei.com>
> 
> 	Looks good to me, thanks!
> 
> Acked-by: Julian Anastasov <ja@ssi.bg>
> 
> 	BTW, why ip_vs_zero_all everywhere? Due to old git version?
> 

I will update the git version and send the patch v3.

Regards,
Junwei