Subject: Re: [PATCH net-next] net/sched: cls_flower: Add user specified data

From: Jiri Pirko <[email-masked]>
Date: Sun, 8 Jan 2017 18:12:51 +0100

Mon, Jan 02, 2017 at 03:59:49PM CET, [email-masked] wrote:
>
>We have been using a cookie as well for actions (which we have been
>using but have been too lazy to submit so far). I am going to port
>it over to the newer kernels and post it.

Hard to deal with something we can't look at :)

>In our case that is intended to be opaque to the kernel i.e kernel
>never inteprets it; in that case it is similar to the kernel
>FIB protocol field.

In case of this patch, kernel also never interprets it. What makes you
think otherwise. Bot kernel, it is always a binary blob.

>
>In your case - could this cookie have been a class/flowid
>(a 32 bit)?
>And would it not make more sense for it the cookie to be
>generic to all classifiers? i.e why is it specific to flower?

Correct, makes sense to have it generic for all cls and perhaps also
acts.

>
>cheers,
>jamal
>
>On 17-01-02 08:13 AM, Paul Blakey wrote:
>> This is to support saving extra data that might be helpful on retrieval.
>> First use case is upcoming openvswitch flow offloads, extra data will
>> include UFID and port mappings for each added flow.
>> 
>> Signed-off-by: Paul Blakey <[email-masked]>
>> Reviewed-by: Roi Dayan <[email-masked]>
>> Acked-by: Jiri Pirko <[email-masked]>
>> ---
>>  include/uapi/linux/pkt_cls.h |  3 +++
>>  net/sched/cls_flower.c       | 22 +++++++++++++++++++++-
>>  2 files changed, 24 insertions(+), 1 deletion(-)
>> 
>> diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
>> index cb4bcdc..ca9bbe3 100644
>> --- a/include/uapi/linux/pkt_cls.h
>> +++ b/include/uapi/linux/pkt_cls.h
>> @@ -471,10 +471,13 @@ enum {
>>  	TCA_FLOWER_KEY_ICMPV6_TYPE,	/* u8 */
>>  	TCA_FLOWER_KEY_ICMPV6_TYPE_MASK,/* u8 */
>> 
>> +	TCA_FLOWER_COOKIE,		/* binary */
>> +
>>  	__TCA_FLOWER_MAX,
>>  };
>> 
>>  #define TCA_FLOWER_MAX (__TCA_FLOWER_MAX - 1)
>> +#define FLOWER_MAX_COOKIE_SIZE 128
>> 
>>  enum {
>>  	TCA_FLOWER_KEY_FLAGS_IS_FRAGMENT = (1 << 0),
>> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
>> index 333f8e2..e2f5b25 100644
>> --- a/net/sched/cls_flower.c
>> +++ b/net/sched/cls_flower.c
>> @@ -85,6 +85,8 @@ struct cls_fl_filter {
>>  	struct rcu_head	rcu;
>>  	struct tc_to_netdev tc;
>>  	struct net_device *hw_dev;
>> +	size_t cookie_len;
>> +	long cookie[0];
>>  };
>> 
>>  static unsigned short int fl_mask_range(const struct fl_flow_mask *mask)
>> @@ -794,6 +796,9 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
>>  	struct cls_fl_filter *fnew;
>>  	struct nlattr *tb[TCA_FLOWER_MAX + 1];
>>  	struct fl_flow_mask mask = {};
>> +	const struct nlattr *attr;
>> +	size_t cookie_len = 0;
>> +	void *cookie;
>>  	int err;
>> 
>>  	if (!tca[TCA_OPTIONS])
>> @@ -806,10 +811,22 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
>>  	if (fold && handle && fold->handle != handle)
>>  		return -EINVAL;
>> 
>> -	fnew = kzalloc(sizeof(*fnew), GFP_KERNEL);
>> +	if (tb[TCA_FLOWER_COOKIE]) {
>> +		attr = tb[TCA_FLOWER_COOKIE];
>> +		cookie_len = nla_len(attr);
>> +		cookie = nla_data(attr);
>> +		if (cookie_len > FLOWER_MAX_COOKIE_SIZE)
>> +			return -EINVAL;
>> +	}
>> +
>> +	fnew = kzalloc(sizeof(*fnew) + cookie_len, GFP_KERNEL);
>>  	if (!fnew)
>>  		return -ENOBUFS;
>> 
>> +	fnew->cookie_len = cookie_len;
>> +	if (cookie_len)
>> +		memcpy(fnew->cookie, cookie, cookie_len);
>> +
>>  	err = tcf_exts_init(&fnew->exts, TCA_FLOWER_ACT, 0);
>>  	if (err < 0)
>>  		goto errout;
>> @@ -1151,6 +1168,9 @@ static int fl_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
>> 
>>  	nla_put_u32(skb, TCA_FLOWER_FLAGS, f->flags);
>> 
>> +	if (f->cookie_len)
>> +		nla_put(skb, TCA_FLOWER_COOKIE, f->cookie_len, f->cookie);
>> +
>>  	if (tcf_exts_dump(skb, &f->exts))
>>  		goto nla_put_failure;
>> 
>> 
>