netdev - Re: [PATCH net-next v5 1/1] net sched actions: Add support for user cookies

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Date:   Sun, 22 Jan 2017 10:13:28 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Jamal Hadi Salim <jhs@...atatu.com>, davem@...emloft.net
Cc:     netdev@...r.kernel.org, jiri@...lanox.com, paulb@...lanox.com,
        john.fastabend@...il.com, simon.horman@...ronome.com,
        mrv@...atatu.com, hadarh@...lanox.com, ogerlitz@...lanox.com,
        roid@...lanox.com, xiyou.wangcong@...il.com, daniel@...earbox.net
Subject: Re: [PATCH net-next v5 1/1] net sched actions: Add support for user
 cookies



On 01/22/2017 04:51 AM, Jamal Hadi Salim wrote:
> From: Jamal Hadi Salim <jhs@...atatu.com>
> 
> Introduce optional 128-bit action cookie.
> Like all other cookie schemes in the networking world (eg in protocols
> like http or existing kernel fib protocol field, etc) the idea is to save
> user state that when retrieved serves as a correlator. The kernel
> _should not_ intepret it.  The user can store whatever they wish in the
> 128 bits.
> 
> Sample exercise(showing variable length use of cookie)
> 
> .. create an accept action with cookie a1b2c3d4
> sudo $TC actions add action ok index 1 cookie a1b2c3d4
> 
> .. dump all gact actions..
> sudo $TC -s actions ls action gact
> 
>     action order 0: gact action pass
>      random type none pass val 0
>      index 1 ref 1 bind 0 installed 5 sec used 5 sec
>     Action statistics:
>     Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
>     backlog 0b 0p requeues 0
>     cookie a1b2c3d4
> 
> .. bind the accept action to a filter..
> sudo $TC filter add dev lo parent ffff: protocol ip prio 1 \
> u32 match ip dst 127.0.0.1/32 flowid 1:1 action gact index 1
> 
> ... send some traffic..
> $ ping 127.0.0.1 -c 3
> PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
> 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.020 ms
> 64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.027 ms
> 64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.038 ms
> 
> --- 127.0.0.1 ping statistics ---
> 3 packets transmitted, 3 received, 0% packet loss, time 2109ms
> rtt min/avg/max/mdev = 0.020/0.028/0.038/0.008 ms 1
> 
> ... show some stats
> $ sudo $TC -s actions get action gact index 1
> 
>     action order 1: gact action pass
>      random type none pass val 0
>      index 1 ref 2 bind 1 installed 204 sec used 5 sec
>     Action statistics:
>         Sent 12168 bytes 164 pkt (dropped 0, overlimits 0 requeues 0)
>     backlog 0b 0p requeues 0
>     cookie a1b2c3d4
> 
> .. try longer cookie...
> $ sudo $TC actions replace action ok index 1 cookie 1234567890abcdef
> .. dump..
> $ sudo $TC -s actions ls action gact
> 
>     action order 1: gact action pass
>      random type none pass val 0
>      index 1 ref 2 bind 1 installed 204 sec used 5 sec
>     Action statistics:
>         Sent 12168 bytes 164 pkt (dropped 0, overlimits 0 requeues 0)
>     backlog 0b 0p requeues 0
>     cookie 1234567890abcdef
> 
> Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>

> +		a->act_cookie->data = nla_memdup(tb[TCA_ACT_COOKIE],
> +						 GFP_KERNEL);
> +		if (!a->act_cookie->data) {
> +			err = -ENOMEM;
> +			tcf_hash_release(a, bind);
> +			goto err_mod;
> +		}

Are not you leaking a->act_cookie here in case nla_memdup() fails here?
-- 
Florian