net sched actions: Add support for user cookies

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

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/act_api.h b/include/net/act_api.h
index 1d716449209e4753a297c61a287077a1eb96e6d8..cfa2ae33da9a19969cb3951b2a2278f61a7fd93f 100644 (file)
--- 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_cookie;
 };
 #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 f0a051480c6c27e1a360a9c041acd582114c4aae..b43077e47d35ababe97c7e2aea4a226b7a803776 100644 (file)
--- 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 {
+       u8  *data;
+       u32 len;
+};
 #endif

diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
index fd373ebd5a442f8da63517c675a114f49b5a2ad7..345551e7141011827625c88b3e941b77b0ddbb0b 100644 (file)
--- 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 cd08df91351d25635d487b2df89db27118280066..3c5e29ba65942801682278aed31644454b82c154 100644 (file)
--- 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 +34,12 @@ static void free_tcf(struct rcu_head *head)
 
        free_percpu(p->cpu_bstats);
        free_percpu(p->cpu_qstats);
+
+       if (p->act_cookie) {
+               kfree(p->act_cookie->data);
+               kfree(p->act_cookie);
+       }
+
        kfree(p);
 }
 
@@ -475,6 +482,12 @@ tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
                goto nla_put_failure;
        if (tcf_action_copy_stats(skb, a, 0))
                goto nla_put_failure;
+       if (a->act_cookie) {
+               if (nla_put(skb, TCA_ACT_COOKIE, a->act_cookie->len,
+                           a->act_cookie->data))
+                       goto nla_put_failure;
+       }
+
        nest = nla_nest_start(skb, TCA_OPTIONS);
        if (nest == NULL)
                goto nla_put_failure;
@@ -516,6 +529,22 @@ int tcf_action_dump(struct sk_buff *skb, struct list_head *actions,
        return err;
 }
 
+int nla_memdup_cookie(struct tc_action *a, struct nlattr **tb)
+{
+       a->act_cookie = kzalloc(sizeof(*a->act_cookie), GFP_KERNEL);
+       if (!a->act_cookie)
+               return -ENOMEM;
+
+       a->act_cookie->data = nla_memdup(tb[TCA_ACT_COOKIE], GFP_KERNEL);
+       if (!a->act_cookie->data) {
+               kfree(a->act_cookie);
+               return -ENOMEM;
+       }
+       a->act_cookie->len = nla_len(tb[TCA_ACT_COOKIE]);
+
+       return 0;
+}
+
 struct tc_action *tcf_action_init_1(struct net *net, struct nlattr *nla,
                                    struct nlattr *est, char *name, int ovr,
                                    int bind)
@@ -575,6 +604,22 @@ struct tc_action *tcf_action_init_1(struct net *net, struct nlattr *nla,
        if (err < 0)
                goto err_mod;
 
+       if (tb[TCA_ACT_COOKIE]) {
+               int cklen = nla_len(tb[TCA_ACT_COOKIE]);
+
+               if (cklen > TC_COOKIE_MAX_SIZE) {
+                       err = -EINVAL;
+                       tcf_hash_release(a, bind);
+                       goto err_mod;
+               }
+
+               err = nla_memdup_cookie(a, tb);
+               if (err < 0) {
+                       tcf_hash_release(a, bind);
+                       goto err_mod;
+               }
+       }
+
        /* 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).