Commit 744676e7 authored by Matteo Croce's avatar Matteo Croce Committed by David S. Miller
Browse files

openvswitch: add TTL decrement action 



New action to decrement TTL instead of setting it to a fixed value.
This action will decrement the TTL and, in case of expired TTL, drop it
or execute an action passed via a nested attribute.
The default TTL expired action is to drop the packet.

Supports both IPv4 and IPv6 via the ttl and hop_limit fields, respectively.

Tested with a corresponding change in the userspace:

    # ovs-dpctl dump-flows
    in_port(2),eth(),eth_type(0x0800), packets:0, bytes:0, used:never, actions:dec_ttl{ttl<=1 action:(drop)},1
    in_port(1),eth(),eth_type(0x0800), packets:0, bytes:0, used:never, actions:dec_ttl{ttl<=1 action:(drop)},2
    in_port(1),eth(),eth_type(0x0806), packets:0, bytes:0, used:never, actions:2
    in_port(2),eth(),eth_type(0x0806), packets:0, bytes:0, used:never, actions:1

    # ping -c1 192.168.0.2 -t 42
    IP (tos 0x0, ttl 41, id 61647, offset 0, flags [DF], proto ICMP (1), length 84)
        192.168.0.1 > 192.168.0.2: ICMP echo request, id 386, seq 1, length 64
    # ping -c1 192.168.0.2 -t 120
    IP (tos 0x0, ttl 119, id 62070, offset 0, flags [DF], proto ICMP (1), length 84)
        192.168.0.1 > 192.168.0.2: ICMP echo request, id 388, seq 1, length 64
    # ping -c1 192.168.0.2 -t 1
    #

Co-developed-by: default avatarBindiya Kurle <bindiyakurle@gmail.com>
Signed-off-by: default avatarBindiya Kurle <bindiyakurle@gmail.com>
Signed-off-by: default avatarMatteo Croce <mcroce@redhat.com>
Acked-by: default avatarPravin B Shelar <pshelar@ovn.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7458bd54

include/uapi/linux/openvswitch.h

+7 −0
Original line number Diff line number Diff line
@@ -958,6 +958,7 @@ enum ovs_action_attr { 
	OVS_ACTION_ATTR_CLONE,        /* Nested OVS_CLONE_ATTR_*.  */

	OVS_ACTION_ATTR_CHECK_PKT_LEN, /* Nested OVS_CHECK_PKT_LEN_ATTR_*. */

	OVS_ACTION_ATTR_ADD_MPLS,     /* struct ovs_action_add_mpls. */

	OVS_ACTION_ATTR_DEC_TTL,      /* Nested OVS_DEC_TTL_ATTR_*. */



	__OVS_ACTION_ATTR_MAX,	      /* Nothing past this will be accepted

				       * from userspace. */
@@ -1050,4 +1051,10 @@ struct ovs_zone_limit { 
	__u32 count;

};



enum ovs_dec_ttl_attr {

	OVS_DEC_TTL_ATTR_UNSPEC,

	OVS_DEC_TTL_ATTR_ACTION,	/* Nested struct nlattr */

	__OVS_DEC_TTL_ATTR_MAX

};



#endif /* _LINUX_OPENVSWITCH_H */

net/openvswitch/actions.c

+67 −0
Original line number Diff line number Diff line
@@ -964,6 +964,25 @@ static int output_userspace(struct datapath *dp, struct sk_buff *skb, 
	return ovs_dp_upcall(dp, skb, key, &upcall, cutlen);

}



static int dec_ttl_exception_handler(struct datapath *dp, struct sk_buff *skb,

				     struct sw_flow_key *key,

				     const struct nlattr *attr, bool last)

{

	/* The first action is always 'OVS_DEC_TTL_ATTR_ARG'. */

	struct nlattr *dec_ttl_arg = nla_data(attr);

	int rem = nla_len(attr);



	if (nla_len(dec_ttl_arg)) {

		struct nlattr *actions = nla_next(dec_ttl_arg, &rem);



		if (actions)

			return clone_execute(dp, skb, key, 0, actions, rem,

					     last, false);

	}

	consume_skb(skb);

	return 0;

}



/* When 'last' is true, sample() should always consume the 'skb'.

 * Otherwise, sample() should keep 'skb' intact regardless what

 * actions are executed within sample().
@@ -1180,6 +1199,45 @@ static int execute_check_pkt_len(struct datapath *dp, struct sk_buff *skb, 
			     nla_len(actions), last, clone_flow_key);

}



static int execute_dec_ttl(struct sk_buff *skb, struct sw_flow_key *key)

{

	int err;



	if (skb->protocol == htons(ETH_P_IPV6)) {

		struct ipv6hdr *nh;



		err = skb_ensure_writable(skb, skb_network_offset(skb) +

					  sizeof(*nh));

		if (unlikely(err))

			return err;



		nh = ipv6_hdr(skb);



		if (nh->hop_limit <= 1)

			return -EHOSTUNREACH;



		key->ip.ttl = --nh->hop_limit;

	} else {

		struct iphdr *nh;

		u8 old_ttl;



		err = skb_ensure_writable(skb, skb_network_offset(skb) +

					  sizeof(*nh));

		if (unlikely(err))

			return err;



		nh = ip_hdr(skb);

		if (nh->ttl <= 1)

			return -EHOSTUNREACH;



		old_ttl = nh->ttl--;

		csum_replace2(&nh->check, htons(old_ttl << 8),

			      htons(nh->ttl << 8));

		key->ip.ttl = nh->ttl;

	}

	return 0;

}



/* Execute a list of actions against 'skb'. */

static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,

			      struct sw_flow_key *key,
@@ -1365,6 +1423,15 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb, 


			break;

		}



		case OVS_ACTION_ATTR_DEC_TTL:

			err = execute_dec_ttl(skb, key);

			if (err == -EHOSTUNREACH) {

				err = dec_ttl_exception_handler(dp, skb, key,

								a, true);

				return err;

			}

			break;

		}



		if (unlikely(err)) {

net/openvswitch/flow_netlink.c

+70 −0
Original line number Diff line number Diff line
@@ -80,6 +80,7 @@ static bool actions_may_change_flow(const struct nlattr *actions) 
		case OVS_ACTION_ATTR_METER:

		case OVS_ACTION_ATTR_CHECK_PKT_LEN:

		case OVS_ACTION_ATTR_ADD_MPLS:

		case OVS_ACTION_ATTR_DEC_TTL:

		default:

			return true;

		}
@@ -2495,6 +2496,39 @@ static int validate_and_copy_sample(struct net *net, const struct nlattr *attr, 
	return 0;

}



static int validate_and_copy_dec_ttl(struct net *net,

				     const struct nlattr *attr,

				     const struct sw_flow_key *key,

				     struct sw_flow_actions **sfa,

				     __be16 eth_type, __be16 vlan_tci,

				     u32 mpls_label_count, bool log)

{

	int start, err;

	u32 nested = true;



	if (!nla_len(attr))

		return ovs_nla_add_action(sfa, OVS_ACTION_ATTR_DEC_TTL,

					  NULL, 0, log);



	start = add_nested_action_start(sfa, OVS_ACTION_ATTR_DEC_TTL, log);

	if (start < 0)

		return start;



	err = ovs_nla_add_action(sfa, OVS_DEC_TTL_ATTR_ACTION, &nested,

				 sizeof(nested), log);



	if (err)

		return err;



	err = __ovs_nla_copy_actions(net, attr, key, sfa, eth_type,

				     vlan_tci, mpls_label_count, log);

	if (err)

		return err;



	add_nested_action_end(*sfa, start);

	return 0;

}



static int validate_and_copy_clone(struct net *net,

				   const struct nlattr *attr,

				   const struct sw_flow_key *key,
@@ -3007,6 +3041,7 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr, 
			[OVS_ACTION_ATTR_CLONE] = (u32)-1,

			[OVS_ACTION_ATTR_CHECK_PKT_LEN] = (u32)-1,

			[OVS_ACTION_ATTR_ADD_MPLS] = sizeof(struct ovs_action_add_mpls),

			[OVS_ACTION_ATTR_DEC_TTL] = (u32)-1,

		};

		const struct ovs_action_push_vlan *vlan;

		int type = nla_type(a);
@@ -3267,6 +3302,15 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr, 
			break;

		}



		case OVS_ACTION_ATTR_DEC_TTL:

			err = validate_and_copy_dec_ttl(net, a, key, sfa,

							eth_type, vlan_tci,

							mpls_label_count, log);

			if (err)

				return err;

			skip_copy = true;

			break;



		default:

			OVS_NLERR(log, "Unknown Action type %d", type);

			return -EINVAL;
@@ -3438,6 +3482,26 @@ out: 
	return err;

}



static int dec_ttl_action_to_attr(const struct nlattr *attr,

				  struct sk_buff *skb)

{

	int err = 0, rem = nla_len(attr);

	struct nlattr *start;



	start = nla_nest_start_noflag(skb, OVS_ACTION_ATTR_DEC_TTL);



	if (!start)

		return -EMSGSIZE;



	err = ovs_nla_put_actions(nla_data(attr), rem, skb);

	if (err)

		nla_nest_cancel(skb, start);

	else

		nla_nest_end(skb, start);



	return err;

}



static int set_action_to_attr(const struct nlattr *a, struct sk_buff *skb)

{

	const struct nlattr *ovs_key = nla_data(a);
@@ -3538,6 +3602,12 @@ int ovs_nla_put_actions(const struct nlattr *attr, int len, struct sk_buff *skb) 
				return err;

			break;



		case OVS_ACTION_ATTR_DEC_TTL:

			err = dec_ttl_action_to_attr(a, skb);

			if (err)

				return err;

			break;



		default:

			if (nla_put(skb, type, nla_len(a), nla_data(a)))

				return -EMSGSIZE;

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