[PATCH net-next v2] openvswitch: add TTL decrement action
From: Matteo Croce
Date: Tue Dec 17 2019 - 10:51:13 EST
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)},1,1
in_port(1),eth(),eth_type(0x0800), packets:0, bytes:0, used:never, actions:dec_ttl{ttl<=1 action:(drop)},1,2
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-authored-by: Bindiya Kurle <bindiyakurle@xxxxxxxxx>
Signed-off-by: Bindiya Kurle <bindiyakurle@xxxxxxxxx>
Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx>
---
include/uapi/linux/openvswitch.h | 22 +++++++
net/openvswitch/actions.c | 71 +++++++++++++++++++++
net/openvswitch/flow_netlink.c | 105 +++++++++++++++++++++++++++++++
3 files changed, 198 insertions(+)
diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index a87b44cd5590..b6684bc04883 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -927,6 +927,7 @@ enum ovs_action_attr {
OVS_ACTION_ATTR_METER, /* u32 meter ID. */
OVS_ACTION_ATTR_CLONE, /* Nested OVS_CLONE_ATTR_*. */
OVS_ACTION_ATTR_CHECK_PKT_LEN, /* Nested OVS_CHECK_PKT_LEN_ATTR_*. */
+ OVS_ACTION_ATTR_DEC_TTL, /* Nested OVS_DEC_TTL_ATTR_*. */
__OVS_ACTION_ATTR_MAX, /* Nothing past this will be accepted
* from userspace. */
@@ -939,6 +940,23 @@ enum ovs_action_attr {
};
#define OVS_ACTION_ATTR_MAX (__OVS_ACTION_ATTR_MAX - 1)
+enum ovs_dec_ttl_attr {
+ OVS_DEC_TTL_ATTR_UNSPEC,
+ OVS_DEC_TTL_ATTR_ACTION_TYPE, /* Action Type u32 */
+ OVS_DEC_TTL_ATTR_ACTION, /* nested action */
+ __OVS_DEC_TTL_ATTR_MAX,
+#ifdef __KERNEL__
+ OVS_DEC_TTL_ATTR_ARG /* struct sample_arg */
+#endif
+};
+
+#ifdef __KERNEL__
+struct dec_ttl_arg {
+ u32 action_type; /* dec_ttl action type.*/
+};
+#endif
+
+#define OVS_DEC_TTL_ATTR_MAX (__OVS_DEC_TTL_ATTR_MAX - 1)
/* Meters. */
#define OVS_METER_FAMILY "ovs_meter"
@@ -1009,6 +1027,10 @@ enum ovs_ct_limit_attr {
__OVS_CT_LIMIT_ATTR_MAX
};
+enum ovs_dec_ttl_action { /*Actions supported by dec_ttl */
+ OVS_DEC_TTL_ACTION_DROP,
+ OVS_DEC_TTL_ACTION_USER_SPACE
+};
#define OVS_CT_LIMIT_ATTR_MAX (__OVS_CT_LIMIT_ATTR_MAX - 1)
#define OVS_ZONE_LIMIT_DEFAULT_ZONE -1
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 4c8395462303..5329668732b1 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -960,6 +960,31 @@ static int output_userspace(struct datapath *dp, struct sk_buff *skb,
return ovs_dp_upcall(dp, skb, key, &upcall, cutlen);
}
+static int dec_ttl(struct datapath *dp, struct sk_buff *skb,
+ struct sw_flow_key *fk, const struct nlattr *attr, bool last)
+{
+ struct nlattr *actions;
+ struct nlattr *dec_ttl_arg;
+ int rem = nla_len(attr);
+ const struct dec_ttl_arg *arg;
+
+ /* The first action is always OVS_DEC_TTL_ATTR_ARG. */
+ dec_ttl_arg = nla_data(attr);
+ arg = nla_data(dec_ttl_arg);
+ actions = nla_next(dec_ttl_arg, &rem);
+
+ switch (arg->action_type) {
+ case OVS_DEC_TTL_ACTION_DROP:
+ consume_skb(skb);
+ break;
+
+ case OVS_DEC_TTL_ACTION_USER_SPACE:
+ return clone_execute(dp, skb, fk, 0, actions, rem, last, false);
+ }
+
+ 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().
@@ -1176,6 +1201,44 @@ 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 = ipv6_hdr(skb);
+
+ err = skb_ensure_writable(skb, skb_network_offset(skb) +
+ sizeof(*nh));
+ if (unlikely(err))
+ return err;
+
+ if (nh->hop_limit <= 1)
+ return -EHOSTUNREACH;
+
+ key->ip.ttl = --nh->hop_limit;
+ } else {
+ struct iphdr *nh = ip_hdr(skb);
+ 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,
@@ -1347,6 +1410,14 @@ 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(dp, skb, key, a, true);
+ return err;
+ }
+ break;
}
if (unlikely(err)) {
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index 65c2e3458ff5..a9eea2ffb8b0 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -61,6 +61,7 @@ static bool actions_may_change_flow(const struct nlattr *actions)
case OVS_ACTION_ATTR_RECIRC:
case OVS_ACTION_ATTR_TRUNC:
case OVS_ACTION_ATTR_USERSPACE:
+ case OVS_ACTION_ATTR_DEC_TTL:
break;
case OVS_ACTION_ATTR_CT:
@@ -2494,6 +2495,59 @@ 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)
+{
+ struct nlattr *attrs[OVS_DEC_TTL_ATTR_MAX + 1] = { 0 };
+ const struct nlattr *action_type, *action;
+ struct nlattr *a;
+ int rem, start, err;
+ struct dec_ttl_arg arg;
+
+ nla_for_each_nested(a, attr, rem) {
+ int type = nla_type(a);
+
+ if (!type || type > OVS_DEC_TTL_ATTR_MAX || attrs[type])
+ return -EINVAL;
+
+ attrs[type] = a;
+ }
+ if (rem)
+ return -EINVAL;
+
+ action_type = attrs[OVS_DEC_TTL_ATTR_ACTION_TYPE];
+ if (!action_type || nla_len(action_type) != sizeof(u32))
+ return -EINVAL;
+
+ start = add_nested_action_start(sfa, OVS_ACTION_ATTR_DEC_TTL, log);
+ if (start < 0)
+ return start;
+
+ arg.action_type = nla_get_u32(action_type);
+ err = ovs_nla_add_action(sfa, OVS_DEC_TTL_ATTR_ARG,
+ &arg, sizeof(arg), log);
+ if (err)
+ return err;
+
+ if (arg.action_type == OVS_DEC_TTL_ACTION_USER_SPACE) {
+ action = attrs[OVS_DEC_TTL_ATTR_ACTION];
+ if (!action || (nla_len(action) && nla_len(action) < NLA_HDRLEN))
+ return -EINVAL;
+
+ err = __ovs_nla_copy_actions(net, action, 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,
@@ -3005,6 +3059,7 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
[OVS_ACTION_ATTR_METER] = sizeof(u32),
[OVS_ACTION_ATTR_CLONE] = (u32)-1,
[OVS_ACTION_ATTR_CHECK_PKT_LEN] = (u32)-1,
+ [OVS_ACTION_ATTR_DEC_TTL] = (u32)-1,
};
const struct ovs_action_push_vlan *vlan;
int type = nla_type(a);
@@ -3233,6 +3288,15 @@ 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;
@@ -3404,6 +3468,41 @@ static int check_pkt_len_action_to_attr(const struct nlattr *attr,
return err;
}
+static int dec_ttl_action_to_attr(const struct nlattr *att, struct sk_buff *skb)
+{
+ struct nlattr *start, *ac_start = NULL, *dec_ttl;
+ int err = 0, rem = nla_len(att);
+ const struct dec_ttl_arg *arg;
+ struct nlattr *actions;
+
+ start = nla_nest_start_noflag(skb, OVS_ACTION_ATTR_DEC_TTL);
+ if (!start)
+ return -EMSGSIZE;
+
+ dec_ttl = nla_data(att);
+ arg = nla_data(dec_ttl);
+ actions = nla_next(dec_ttl, &rem);
+
+ if (nla_put_u32(skb, OVS_DEC_TTL_ATTR_ACTION_TYPE, arg->action_type)) {
+ nla_nest_cancel(skb, start);
+ return -EMSGSIZE;
+ }
+
+ if (arg->action_type == OVS_DEC_TTL_ACTION_USER_SPACE) {
+ ac_start = nla_nest_start_noflag(skb, OVS_DEC_TTL_ATTR_ACTION);
+ if (!ac_start) {
+ nla_nest_cancel(skb, ac_start);
+ nla_nest_cancel(skb, start);
+ return -EMSGSIZE;
+ }
+ err = ovs_nla_put_actions(actions, rem, skb);
+ nla_nest_end(skb, ac_start);
+ }
+ 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);
@@ -3504,6 +3603,12 @@ 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;
--
2.23.0