macvlan: remove tmp interface when name already used in netns

If the interface name is already used in the netns the rename call will
fail and netavark error out. This is correct but before it returns it
should remove the tmp interface otherwise we end up leaking it.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

src/network/macvlan.rs

@@ -1,6 +1,6 @@
 use std::{collections::HashMap, net::IpAddr, os::unix::prelude::RawFd};
 
-use log::debug;
+use log::{debug, error};
 use netlink_packet_route::nlas::link::{InfoData, InfoKind, InfoMacVlan, Nla};
 use rand::distributions::{Alphanumeric, DistString};
 
@@ -198,12 +198,22 @@ fn setup(
                         // retry, error could EEXIST again because we pick a random name
                         continue;
                     }
+
                     let link = netns
-                        .get_link(netlink::LinkID::Name(tmp_name))
+                        .get_link(netlink::LinkID::Name(tmp_name.clone()))
                         .wrap("get tmp macvlan interface")?;
                     netns
                         .set_link_name(link.header.index, if_name.to_string())
-                        .wrap("rename tmp macvlan interface")?;
+                        .wrap("rename tmp macvlan interface")
+                        .map_err(|err| {
+                            // If there is an error here most likely the name in the netns is already used,
+                            // make sure to delete the tmp interface.
+                            if let Err(err) = netns.del_link(netlink::LinkID::ID(link.header.index))
+                            {
+                                error!("failed to delete tmp macvlan link {}: {}", tmp_name, err);
+                            };
+                            err
+                        })?;
 
                     // successful run, break out of loop
                     break;

test/300-macvlan.bats

@@ -283,3 +283,52 @@ EOF
 
    run_netavark teardown $(get_container_netns_path) <<<"$config"
 }
+
+@test "macvlan same interface name on container" {
+
+   read -r -d '\0' config <<EOF
+{
+   "container_id": "someID",
+   "container_name": "someName",
+   "networks": {
+      "podman": {
+         "static_ips": [
+            "10.88.0.2"
+         ],
+         "interface_name": "eth0"
+      }
+   },
+   "network_info": {
+      "podman": {
+         "name": "podman",
+         "id": "2f259bab93aaaaa2542ba43ef33eb990d0999ee1b9924b557b7be53c0b7a1bb9",
+         "driver": "macvlan",
+         "network_interface": "dummy0",
+         "subnets": [
+            {
+               "subnet": "10.88.0.0/16",
+               "gateway": "10.88.0.1"
+            }
+         ],
+         "ipv6_enabled": false,
+         "internal": false,
+         "dns_enabled": false,
+         "ipam_options": {
+            "driver": "host-local"
+         }
+      }
+   }
+}\0
+EOF
+
+   run_in_container_netns ip link add eth0 type dummy
+
+   expected_rc=1 run_netavark setup $(get_container_netns_path) <<<"$config"
+
+   # make sure the tmp interface is not leaked on the host or netns
+   run_in_host_netns ip -o link show
+   assert "${#lines[@]}" == 2 "only two interfaces (lo, dummy0) on the host, the tmp macvlan interface should be gone"
+
+   run_in_container_netns ip -o link show
+   assert "${#lines[@]}" == 2 "only two interfaces (lo, eth0) in the netns, the tmp macvlan interface should be gone"
+}