nspawn: add new --network-veth-extra= switch for defining additional veth links

The new switch operates like --network-veth, but may be specified
multiple times (to define multiple link pairs) and allows flexible
definition of the interface names.

This is an independent reimplementation of #1678, but defines different
semantics, keeping the behaviour completely independent of
--network-veth. It also comes will full hook-up for .nspawn files, and
the matching documentation.

1 files changed, 129 insertions, 28 deletions

diff --git a/src/nspawn/nspawn-network.c b/src/nspawn/nspawn-network.c
index 29384b60b2..c71552879d 100644
--- a/src/nspawn/nspawn-network.c
+++ b/src/nspawn/nspawn-network.c
@@ -37,6 +37,8 @@
 
 #define HOST_HASH_KEY SD_ID128_MAKE(1a,37,6f,c7,46,ec,45,0b,ad,a3,d5,31,06,60,5d,b1)
 #define CONTAINER_HASH_KEY SD_ID128_MAKE(c3,c4,f9,19,b5,57,b2,1c,e6,cf,14,27,03,9c,ee,a2)
+#define VETH_EXTRA_HOST_HASH_KEY SD_ID128_MAKE(48,c7,f6,b7,ea,9d,4c,9e,b7,28,d4,de,91,d5,bf,66)
+#define VETH_EXTRA_CONTAINER_HASH_KEY SD_ID128_MAKE(af,50,17,61,ce,f9,4d,35,84,0d,2b,20,54,be,ce,59)
 #define MACVLAN_HASH_KEY SD_ID128_MAKE(00,13,6d,bc,66,83,44,81,bb,0c,f9,51,1f,24,a6,6f)
 
 static int generate_mac(
@@ -84,42 +86,32 @@ static int generate_mac(
         return 0;
 }
 
-int setup_veth(const char *machine_name,
-               pid_t pid,
-               char iface_name[IFNAMSIZ],
-               bool bridge) {
+static int add_veth(
+                sd_netlink *rtnl,
+                pid_t pid,
+                const char *ifname_host,
+                const struct ether_addr *mac_host,
+                const char *ifname_container,
+                const struct ether_addr *mac_container) {
 
         _cleanup_netlink_message_unref_ sd_netlink_message *m = NULL;
-        _cleanup_netlink_unref_ sd_netlink *rtnl = NULL;
-        struct ether_addr mac_host, mac_container;
-        int r, i;
-
-        /* Use two different interface name prefixes depending whether
-         * we are in bridge mode or not. */
-        snprintf(iface_name, IFNAMSIZ - 1, "%s-%s",
-                 bridge ? "vb" : "ve", machine_name);
-
-        r = generate_mac(machine_name, &mac_container, CONTAINER_HASH_KEY, 0);
-        if (r < 0)
-                return log_error_errno(r, "Failed to generate predictable MAC address for container side: %m");
-
-        r = generate_mac(machine_name, &mac_host, HOST_HASH_KEY, 0);
-        if (r < 0)
-                return log_error_errno(r, "Failed to generate predictable MAC address for host side: %m");
+        int r;
 
-        r = sd_netlink_open(&rtnl);
-        if (r < 0)
-                return log_error_errno(r, "Failed to connect to netlink: %m");
+        assert(rtnl);
+        assert(ifname_host);
+        assert(mac_host);
+        assert(ifname_container);
+        assert(mac_container);
 
         r = sd_rtnl_message_new_link(rtnl, &m, RTM_NEWLINK, 0);
         if (r < 0)
                 return log_error_errno(r, "Failed to allocate netlink message: %m");
 
-        r = sd_netlink_message_append_string(m, IFLA_IFNAME, iface_name);
+        r = sd_netlink_message_append_string(m, IFLA_IFNAME, ifname_host);
         if (r < 0)
                 return log_error_errno(r, "Failed to add netlink interface name: %m");
 
-        r = sd_netlink_message_append_ether_addr(m, IFLA_ADDRESS, &mac_host);
+        r = sd_netlink_message_append_ether_addr(m, IFLA_ADDRESS, mac_host);
         if (r < 0)
                 return log_error_errno(r, "Failed to add netlink MAC address: %m");
 
@@ -135,11 +127,11 @@ int setup_veth(const char *machine_name,
         if (r < 0)
                 return log_error_errno(r, "Failed to open netlink container: %m");
 
-        r = sd_netlink_message_append_string(m, IFLA_IFNAME, "host0");
+        r = sd_netlink_message_append_string(m, IFLA_IFNAME, ifname_container);
         if (r < 0)
                 return log_error_errno(r, "Failed to add netlink interface name: %m");
 
-        r = sd_netlink_message_append_ether_addr(m, IFLA_ADDRESS, &mac_container);
+        r = sd_netlink_message_append_ether_addr(m, IFLA_ADDRESS, mac_container);
         if (r < 0)
                 return log_error_errno(r, "Failed to add netlink MAC address: %m");
 
@@ -161,7 +153,44 @@ int setup_veth(const char *machine_name,
 
         r = sd_netlink_call(rtnl, m, 0, NULL);
         if (r < 0)
-                return log_error_errno(r, "Failed to add new veth interfaces (host0, %s): %m", iface_name);
+                return log_error_errno(r, "Failed to add new veth interfaces (%s:%s): %m", ifname_host, ifname_container);
+
+        return 0;
+}
+
+int setup_veth(const char *machine_name,
+               pid_t pid,
+               char iface_name[IFNAMSIZ],
+               bool bridge) {
+
+        _cleanup_netlink_unref_ sd_netlink *rtnl = NULL;
+        struct ether_addr mac_host, mac_container;
+        int r, i;
+
+        assert(machine_name);
+        assert(pid > 0);
+        assert(iface_name);
+
+        /* Use two different interface name prefixes depending whether
+         * we are in bridge mode or not. */
+        snprintf(iface_name, IFNAMSIZ - 1, "%s-%s",
+                 bridge ? "vb" : "ve", machine_name);
+
+        r = generate_mac(machine_name, &mac_container, CONTAINER_HASH_KEY, 0);
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate predictable MAC address for container side: %m");
+
+        r = generate_mac(machine_name, &mac_host, HOST_HASH_KEY, 0);
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate predictable MAC address for host side: %m");
+
+        r = sd_netlink_open(&rtnl);
+        if (r < 0)
+                return log_error_errno(r, "Failed to connect to netlink: %m");
+
+        r = add_veth(rtnl, pid, iface_name, &mac_host, "host0", &mac_container);
+        if (r < 0)
+                return r;
 
         i = (int) if_nametoindex(iface_name);
         if (i <= 0)
@@ -170,6 +199,47 @@ int setup_veth(const char *machine_name,
         return i;
 }
 
+int setup_veth_extra(
+                const char *machine_name,
+                pid_t pid,
+                char **pairs) {
+
+        _cleanup_netlink_unref_ sd_netlink *rtnl = NULL;
+        uint64_t idx = 0;
+        char **a, **b;
+        int r;
+
+        assert(machine_name);
+        assert(pid > 0);
+
+        if (strv_isempty(pairs))
+                return 0;
+
+        r = sd_netlink_open(&rtnl);
+        if (r < 0)
+                return log_error_errno(r, "Failed to connect to netlink: %m");
+
+        STRV_FOREACH_PAIR(a, b, pairs) {
+                struct ether_addr mac_host, mac_container;
+
+                r = generate_mac(machine_name, &mac_container, VETH_EXTRA_CONTAINER_HASH_KEY, idx);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to generate predictable MAC address for container side of extra veth link: %m");
+
+                r = generate_mac(machine_name, &mac_host, VETH_EXTRA_HOST_HASH_KEY, idx);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to generate predictable MAC address for container side of extra veth link: %m");
+
+                r = add_veth(rtnl, pid, *a, &mac_host, *b, &mac_container);
+                if (r < 0)
+                        return r;
+
+                idx ++;
+        }
+
+        return 0;
+}
+
 int setup_bridge(const char *veth_name, const char *bridge_name) {
         _cleanup_netlink_message_unref_ sd_netlink_message *m = NULL;
         _cleanup_netlink_unref_ sd_netlink *rtnl = NULL;
@@ -439,3 +509,34 @@ int setup_ipvlan(const char *machine_name, pid_t pid, char **ifaces) {
 
         return 0;
 }
+
+int veth_extra_parse(char ***l, const char *p) {
+        _cleanup_free_ char *a = NULL, *b = NULL;
+        int r;
+
+        r = extract_first_word(&p, &a, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
+        if (r < 0)
+                return r;
+        if (r == 0 || isempty(a))
+                return -EINVAL;
+
+        r = extract_first_word(&p, &b, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
+        if (r < 0)
+                return r;
+        if (r == 0 || isempty(b)) {
+                free(b);
+                b = strdup(a);
+                if (!b)
+                        return -ENOMEM;
+        }
+
+        if (p)
+                return -EINVAL;
+
+        r = strv_push_pair(l, a, b);
+        if (r < 0)
+                return -ENOMEM;
+
+        a = b = NULL;
+        return 0;
+}