zebra: handle nexthop vrf_id in ZEBRA_MPLS_LABELS messages

This commit addresses the case where a service wants to install
an LSP entry to a next-hop located in a VRF instance. The incoming
MPLS packet is on the namespace and has to be directed to a nexthop
located behind an interface that sits in a specific VRF instance.
The below iproute command can illustrate:

  > ip link add vrf1 type vrf table 10
  > ip link set dev vrf1 up
  > ip link set dev eth0 master vrf1
  > ip a a 192.0.2.1/24 dev eth0
  > ip -f mpls route add 105 via inet 192.0.2.45 dev eth0

If a service uses the ZEBRA_MPLS_LABELS messages, then the LSP
message is ignored: from zebra perspective, the MPLS entries are
visible via the 'show mpls table' command, but no LSP entry is
installed in the kernel.

The issue is in the nhlfe_nexthop_active_ipv[4/6] function: the
outgoing interface mentioned in the nexthop is searched in the
main VRF, whereas the interface is in a separate VRF. The interface
is not found, and the nhlfe to install is considered not active.

To address this issue, reuse the incoming vrf_id parameter transmitted
in the nexthop structure from the ZEBRA_MPLS_LABELS message. When
creating an NHLFE entry, the vrf_id is used instead of the DEFAULT_VRF.
And the nhlfe entry can be considered as active.

One alternate solution to reuse the vrf_id parameter in the mpls network
context would be to modify the search function in nhlfe_nexthop_active..()
function: looking for an existing ifindex in the zns. However, this
solution may not fit later when netns backend would be used.

Note that some changes have not been done yet and are considered
sufficient for now:
- The 'nhlfe_find' API: the assumption is done that only the linux vrf
backend is used for now.

- The 'mpls_lsp_install()' API: It is currently used by the CLI command
which does not handle the interface parameter, and the SRTE service, whih
always sends LSPs towards a nexthop located in the VRF_DEFAULT.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

diff --git a/zebra/zebra_mpls.c b/zebra/zebra_mpls.c
index 11eee62c49a26c6e60a8d07db63be1c8e9958a0e..38a76a299879d7b99e304f11addff4c362f2abc2 100644 (file)
--- a/zebra/zebra_mpls.c
+++ b/zebra/zebra_mpls.c
@@ -97,8 +97,8 @@ static struct zebra_nhlfe *nhlfe_find(struct nhlfe_list_head *list,
 static struct zebra_nhlfe *
 nhlfe_add(struct zebra_lsp *lsp, enum lsp_types_t lsp_type,
          enum nexthop_types_t gtype, const union g_addr *gate,
-         ifindex_t ifindex, uint8_t num_labels, const mpls_label_t *labels,
-         bool is_backup);
+         ifindex_t ifindex, vrf_id_t vrf_id, uint8_t num_labels,
+         const mpls_label_t *labels, bool is_backup);
 static int nhlfe_del(struct zebra_nhlfe *nhlfe);
 static void nhlfe_free(struct zebra_nhlfe *nhlfe);
 static void nhlfe_out_label_update(struct zebra_nhlfe *nhlfe,
@@ -212,11 +212,11 @@ static int lsp_install(struct zebra_vrf *zvrf, mpls_label_t label,
                        changed++;
                } else {
                        /* Add LSP entry to this nexthop */
-                       nhlfe = nhlfe_add(lsp, lsp_type, nexthop->type,
-                                         &nexthop->gate, nexthop->ifindex,
-                                         nexthop->nh_label->num_labels,
-                                         nexthop->nh_label->label,
-                                         false /*backup*/);
+                       nhlfe = nhlfe_add(
+                               lsp, lsp_type, nexthop->type, &nexthop->gate,
+                               nexthop->ifindex, nexthop->vrf_id,
+                               nexthop->nh_label->num_labels,
+                               nexthop->nh_label->label, false /*backup*/);
                        if (!nhlfe)
                                return -1;
 
@@ -1236,6 +1236,7 @@ static int nhlfe_nhop_match(struct zebra_nhlfe *nhlfe,
 
 /*
  * Locate NHLFE that matches with passed info.
+ * TODO: handle vrf_id if vrf backend is netns based
  */
 static struct zebra_nhlfe *nhlfe_find(struct nhlfe_list_head *list,
                                      enum lsp_types_t lsp_type,
@@ -1261,7 +1262,8 @@ static struct zebra_nhlfe *nhlfe_find(struct nhlfe_list_head *list,
 static struct zebra_nhlfe *
 nhlfe_alloc(struct zebra_lsp *lsp, enum lsp_types_t lsp_type,
            enum nexthop_types_t gtype, const union g_addr *gate,
-           ifindex_t ifindex, uint8_t num_labels, const mpls_label_t *labels)
+           ifindex_t ifindex, vrf_id_t vrf_id, uint8_t num_labels,
+           const mpls_label_t *labels)
 {
        struct zebra_nhlfe *nhlfe;
        struct nexthop *nexthop;
@@ -1278,7 +1280,7 @@ nhlfe_alloc(struct zebra_lsp *lsp, enum lsp_types_t lsp_type,
 
        nexthop_add_labels(nexthop, lsp_type, num_labels, labels);
 
-       nexthop->vrf_id = VRF_DEFAULT;
+       nexthop->vrf_id = vrf_id;
        nexthop->type = gtype;
        switch (nexthop->type) {
        case NEXTHOP_TYPE_IPV4:
@@ -1313,12 +1315,11 @@ nhlfe_alloc(struct zebra_lsp *lsp, enum lsp_types_t lsp_type,
  * Add primary or backup NHLFE. Base entry must have been created and
  * duplicate check done.
  */
-static struct zebra_nhlfe *nhlfe_add(struct zebra_lsp *lsp,
-                                    enum lsp_types_t lsp_type,
-                                    enum nexthop_types_t gtype,
-                                    const union g_addr *gate,
-                                    ifindex_t ifindex, uint8_t num_labels,
-                                    const mpls_label_t *labels, bool is_backup)
+static struct zebra_nhlfe *
+nhlfe_add(struct zebra_lsp *lsp, enum lsp_types_t lsp_type,
+         enum nexthop_types_t gtype, const union g_addr *gate,
+         ifindex_t ifindex, vrf_id_t vrf_id, uint8_t num_labels,
+         const mpls_label_t *labels, bool is_backup)
 {
        struct zebra_nhlfe *nhlfe;
 
@@ -1326,8 +1327,8 @@ static struct zebra_nhlfe *nhlfe_add(struct zebra_lsp *lsp,
                return NULL;
 
        /* Allocate new object */
-       nhlfe = nhlfe_alloc(lsp, lsp_type, gtype, gate, ifindex, num_labels,
-                           labels);
+       nhlfe = nhlfe_alloc(lsp, lsp_type, gtype, gate, ifindex, vrf_id,
+                           num_labels, labels);
 
        if (!nhlfe)
                return NULL;
@@ -2236,8 +2237,8 @@ zebra_mpls_lsp_add_nhlfe(struct zebra_lsp *lsp, enum lsp_types_t lsp_type,
                         const mpls_label_t *out_labels)
 {
        /* Just a public pass-through to the internal implementation */
-       return nhlfe_add(lsp, lsp_type, gtype, gate, ifindex, num_labels,
-                        out_labels, false /*backup*/);
+       return nhlfe_add(lsp, lsp_type, gtype, gate, ifindex, VRF_DEFAULT,
+                        num_labels, out_labels, false /*backup*/);
 }
 
 /*
@@ -2251,8 +2252,8 @@ struct zebra_nhlfe *zebra_mpls_lsp_add_backup_nhlfe(
        uint8_t num_labels, const mpls_label_t *out_labels)
 {
        /* Just a public pass-through to the internal implementation */
-       return nhlfe_add(lsp, lsp_type, gtype, gate, ifindex, num_labels,
-                        out_labels, true);
+       return nhlfe_add(lsp, lsp_type, gtype, gate, ifindex, VRF_DEFAULT,
+                        num_labels, out_labels, true);
 }
 
 /*
@@ -2264,10 +2265,10 @@ struct zebra_nhlfe *zebra_mpls_lsp_add_nh(struct zebra_lsp *lsp,
 {
        struct zebra_nhlfe *nhlfe;
 
-       nhlfe = nhlfe_add(lsp, lsp_type, nh->type, &nh->gate, nh->ifindex,
-                         nh->nh_label ? nh->nh_label->num_labels : 0,
-                         nh->nh_label ? nh->nh_label->label : NULL,
-                         false /*backup*/);
+       nhlfe = nhlfe_add(
+               lsp, lsp_type, nh->type, &nh->gate, nh->ifindex, nh->vrf_id,
+               nh->nh_label ? nh->nh_label->num_labels : 0,
+               nh->nh_label ? nh->nh_label->label : NULL, false /*backup*/);
 
        return nhlfe;
 }
@@ -2283,6 +2284,7 @@ struct zebra_nhlfe *zebra_mpls_lsp_add_backup_nh(struct zebra_lsp *lsp,
        struct zebra_nhlfe *nhlfe;
 
        nhlfe = nhlfe_add(lsp, lsp_type, nh->type, &nh->gate, nh->ifindex,
+                         nh->vrf_id,
                          nh->nh_label ? nh->nh_label->num_labels : 0,
                          nh->nh_label ? nh->nh_label->label : NULL, true);
 
@@ -3102,7 +3104,7 @@ static struct zebra_nhlfe *
 lsp_add_nhlfe(struct zebra_lsp *lsp, enum lsp_types_t type,
              uint8_t num_out_labels, const mpls_label_t *out_labels,
              enum nexthop_types_t gtype, const union g_addr *gate,
-             ifindex_t ifindex, bool is_backup)
+             ifindex_t ifindex, vrf_id_t vrf_id, bool is_backup)
 {
        struct zebra_nhlfe *nhlfe;
        char buf[MPLS_LABEL_STRLEN];
@@ -3164,7 +3166,7 @@ lsp_add_nhlfe(struct zebra_lsp *lsp, enum lsp_types_t type,
                }
        } else {
                /* Add LSP entry to this nexthop */
-               nhlfe = nhlfe_add(lsp, type, gtype, gate, ifindex,
+               nhlfe = nhlfe_add(lsp, type, gtype, gate, ifindex, vrf_id,
                                  num_out_labels, out_labels, is_backup);
                if (!nhlfe)
                        return NULL;
@@ -3196,6 +3198,8 @@ lsp_add_nhlfe(struct zebra_lsp *lsp, enum lsp_types_t type,
 /*
  * Install an LSP and forwarding entry; used primarily
  * from vrf zapi message processing.
+ * TODO: handle vrf_id parameter when mpls API extends to interface or SRTE
+ * changes
  */
 int mpls_lsp_install(struct zebra_vrf *zvrf, enum lsp_types_t type,
                     mpls_label_t in_label, uint8_t num_out_labels,
@@ -3217,7 +3221,7 @@ int mpls_lsp_install(struct zebra_vrf *zvrf, enum lsp_types_t type,
        lsp = hash_get(lsp_table, &tmp_ile, lsp_alloc);
 
        nhlfe = lsp_add_nhlfe(lsp, type, num_out_labels, out_labels, gtype,
-                             gate, ifindex, false /*backup*/);
+                             gate, ifindex, VRF_DEFAULT, false /*backup*/);
        if (nhlfe == NULL)
                return -1;
 
@@ -3236,8 +3240,8 @@ static int lsp_znh_install(struct zebra_lsp *lsp, enum lsp_types_t type,
 {
        struct zebra_nhlfe *nhlfe;
 
-       nhlfe = lsp_add_nhlfe(lsp, type, znh->label_num, znh->labels,
-                             znh->type, &znh->gate, znh->ifindex,
+       nhlfe = lsp_add_nhlfe(lsp, type, znh->label_num, znh->labels, znh->type,
+                             &znh->gate, znh->ifindex, znh->vrf_id,
                              false /*backup*/);
        if (nhlfe == NULL)
                return -1;
@@ -3274,9 +3278,9 @@ static int lsp_backup_znh_install(struct zebra_lsp *lsp, enum lsp_types_t type,
 {
        struct zebra_nhlfe *nhlfe;
 
-       nhlfe = lsp_add_nhlfe(lsp, type, znh->label_num,
-                             znh->labels, znh->type, &znh->gate,
-                             znh->ifindex, true /*backup*/);
+       nhlfe = lsp_add_nhlfe(lsp, type, znh->label_num, znh->labels, znh->type,
+                             &znh->gate, znh->ifindex, znh->vrf_id,
+                             true /*backup*/);
        if (nhlfe == NULL) {
                if (IS_ZEBRA_DEBUG_MPLS)
                        zlog_debug("%s: unable to add backup nhlfe, label: %u",
@@ -3607,8 +3611,8 @@ int zebra_mpls_static_lsp_add(struct zebra_vrf *zvrf, mpls_label_t in_label,
 
        } else {
                /* Add static LSP entry to this nexthop */
-               nhlfe = nhlfe_add(lsp, ZEBRA_LSP_STATIC, gtype, gate,
-                                 ifindex, 1, &out_label, false /*backup*/);
+               nhlfe = nhlfe_add(lsp, ZEBRA_LSP_STATIC, gtype, gate, ifindex,
+                                 VRF_DEFAULT, 1, &out_label, false /*backup*/);
                if (!nhlfe)
                        return -1;