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Date: Wed, 18 Jan 2017 13:47:15 +0200
From: Paul Blakey <paulb@...lanox.com>
To: Jamal Hadi Salim <jhs@...atatu.com>, <davem@...emloft.net>
CC: <paulb@...lanox.com>, <netdev@...r.kernel.org>,
<jiri@...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 v4 1/2] net sched actions: Add support for user
cookies
On 17/01/2017 13:11, 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>
> ---
> include/net/act_api.h | 1 +
> include/net/pkt_cls.h | 8 ++++++++
> include/uapi/linux/pkt_cls.h | 3 +++
> net/sched/act_api.c | 25 +++++++++++++++++++++++++
> 4 files changed, 37 insertions(+)
>
> diff --git a/include/net/act_api.h b/include/net/act_api.h
> index 1d71644..0692458 100644
> --- a/include/net/act_api.h
> +++ b/include/net/act_api.h
> @@ -41,6 +41,7 @@ struct tc_action {
> struct rcu_head tcfa_rcu;
> struct gnet_stats_basic_cpu __percpu *cpu_bstats;
> struct gnet_stats_queue __percpu *cpu_qstats;
> + struct tc_cookie *act_ck;
> };
> #define tcf_head common.tcfa_head
> #define tcf_index common.tcfa_index
> diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
> index f0a0514..e0bc7e8 100644
> --- a/include/net/pkt_cls.h
> +++ b/include/net/pkt_cls.h
> @@ -515,4 +515,12 @@ struct tc_cls_bpf_offload {
> u32 gen_flags;
> };
>
> +
> +/* This structure holds cookie structure that is passed from user
> + * to the kernel for actions and classifiers
> + */
> +struct tc_cookie {
> + unsigned char ck[TC_COOKIE_MAX_SIZE];
> + unsigned char ck_len;
> +};
> #endif
> diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
> index 1e5e1dd..2d2414e 100644
> --- a/include/uapi/linux/pkt_cls.h
> +++ b/include/uapi/linux/pkt_cls.h
> @@ -4,6 +4,8 @@
> #include <linux/types.h>
> #include <linux/pkt_sched.h>
>
> +#define TC_COOKIE_MAX_SIZE 16
> +
> /* Action attributes */
> enum {
> TCA_ACT_UNSPEC,
> @@ -12,6 +14,7 @@ enum {
> TCA_ACT_INDEX,
> TCA_ACT_STATS,
> TCA_ACT_PAD,
> + TCA_ACT_COOKIE,
> __TCA_ACT_MAX
> };
>
> diff --git a/net/sched/act_api.c b/net/sched/act_api.c
> index f04715a..43f1f42 100644
> --- a/net/sched/act_api.c
> +++ b/net/sched/act_api.c
> @@ -24,6 +24,7 @@
> #include <net/net_namespace.h>
> #include <net/sock.h>
> #include <net/sch_generic.h>
> +#include <net/pkt_cls.h>
> #include <net/act_api.h>
> #include <net/netlink.h>
>
> @@ -33,6 +34,7 @@ static void free_tcf(struct rcu_head *head)
>
> free_percpu(p->cpu_bstats);
> free_percpu(p->cpu_qstats);
> + kfree(p->act_ck);
> kfree(p);
> }
>
> @@ -475,6 +477,12 @@ int tcf_action_destroy(struct list_head *actions, int bind)
> goto nla_put_failure;
> if (tcf_action_copy_stats(skb, a, 0))
> goto nla_put_failure;
> + if (a->act_ck) {
> + if (nla_put(skb, TCA_ACT_COOKIE, a->act_ck->ck_len,
> + a->act_ck))
> + goto nla_put_failure;
> + }
> +
> nest = nla_nest_start(skb, TCA_OPTIONS);
> if (nest == NULL)
> goto nla_put_failure;
> @@ -575,6 +583,23 @@ struct tc_action *tcf_action_init_1(struct net *net, struct nlattr *nla,
> if (err < 0)
> goto err_mod;
>
> + if (tb[TCA_ACT_COOKIE]) {
> + if (nla_len(tb[TCA_ACT_COOKIE]) > TC_COOKIE_MAX_SIZE) {
> + err = -EINVAL;
> + goto err_mod;
> + }
> +
> + a->act_ck = kzalloc(sizeof(*a->act_ck), GFP_KERNEL);
Hi Jamal, How about
struct tc_cookie {
unsigned int len;
unsigned long ck[0];
};
and then:
a->act_ck = kzalloc(sizeof(*a->act_ck) + nla_len(tb[TCA_ACT_COOKIE]),
GFP_KERNEL);
to save some space?
> + if (unlikely(!a->act_ck)) {
> + err = -ENOMEM;
> + goto err_mod;
> + }
> +
> + memcpy(a->act_ck->ck, nla_data(tb[TCA_ACT_COOKIE]),
> + nla_len(tb[TCA_ACT_COOKIE]));
> + a->act_ck->ck_len = nla_len(tb[TCA_ACT_COOKIE]);
> + }
> +
> /* module count goes up only when brand new policy is created
> * if it exists and is only bound to in a_o->init() then
> * ACT_P_CREATED is not returned (a zero is).
>
Besides if I'll reuse tc_cookie for classifiers, I'll need 20 bytes :)
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