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[149.6.153.186]) by smtp.gmail.com with ESMTPSA id x5sm2290277wmj.7.2019.11.12.02.25.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Nov 2019 02:25:21 -0800 (PST) From: Matteo Croce To: netdev@vger.kernel.org, dev@openvswitch.org Cc: linux-kernel@vger.kernel.org, Pravin B Shelar , "David S. Miller" , Bindiya Kurle Subject: [PATCH net-next] openvswitch: add TTL decrement action Date: Tue, 12 Nov 2019 11:25:18 +0100 Message-Id: <20191112102518.4406-1-mcroce@redhat.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 X-MC-Unique: zTGsW_W7NRKKCPQO8JnMig-1 X-Mimecast-Spam-Score: 0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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, send the packet to userspace via output_userspace() to take care of it. 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,1 in_port(1),eth(),eth_type(0x0800), packets:0, bytes:0, used:never, actions:dec_ttl,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 Signed-off-by: Bindiya Kurle Signed-off-by: Matteo Croce --- include/uapi/linux/openvswitch.h | 2 ++ net/openvswitch/actions.c | 46 ++++++++++++++++++++++++++++++++ net/openvswitch/flow_netlink.c | 6 +++++ 3 files changed, 54 insertions(+) diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h index 1887a451c388..a3bdb1ecd1e7 100644 --- a/include/uapi/linux/openvswitch.h +++ b/include/uapi/linux/openvswitch.h @@ -890,6 +890,7 @@ struct check_pkt_len_arg { * @OVS_ACTION_ATTR_CHECK_PKT_LEN: Check the packet length and execute a set * of actions if greater than the specified packet length, else execute * another set of actions. + * @OVS_ACTION_ATTR_DEC_TTL: Decrement the IP TTL. * * Only a single header can be set with a single %OVS_ACTION_ATTR_SET. Not all * fields within a header are modifiable, e.g. the IPv4 protocol and fragment @@ -925,6 +926,7 @@ 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, /* Decrement ttl action */ __OVS_ACTION_ATTR_MAX, /* Nothing past this will be accepted * from userspace. */ diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c index 12936c151cc0..077b7f309c93 100644 --- a/net/openvswitch/actions.c +++ b/net/openvswitch/actions.c @@ -1174,6 +1174,43 @@ 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; + + 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, @@ -1345,6 +1382,15 @@ 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) { + output_userspace(dp, skb, key, a, attr, + len, OVS_CB(skb)->cutlen); + OVS_CB(skb)->cutlen = 0; + } + break; } if (unlikely(err)) { diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c index 65c2e3458ff5..d17f2d4b420f 100644 --- a/net/openvswitch/flow_netlink.c +++ b/net/openvswitch/flow_netlink.c @@ -79,6 +79,7 @@ static bool actions_may_change_flow(const struct nlattr *actions) case OVS_ACTION_ATTR_SET_MASKED: case OVS_ACTION_ATTR_METER: case OVS_ACTION_ATTR_CHECK_PKT_LEN: + case OVS_ACTION_ATTR_DEC_TTL: default: return true; } @@ -3005,6 +3006,7 @@ 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] = 0, }; const struct ovs_action_push_vlan *vlan; int type = nla_type(a); @@ -3233,6 +3235,10 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr, break; } + case OVS_ACTION_ATTR_DEC_TTL: + /* Nothing to do. */ + break; + default: OVS_NLERR(log, "Unknown Action type %d", type); return -EINVAL;