Hello!

On first sight, this looks good. Gonna do some checks and tests and let you know whether anything more is needed from you.

Thank you for your patch!
Maria

On 8/24/23 01:38, Pavel Šorejs via Bird-users wrote:
Here is first version - based on master


Pavel

---
 doc/bird.sgml          | 11 ++++++-----
 sysdep/linux/netlink.c |  2 +-
 sysdep/unix/krt.Y      |  7 ++++++-
 sysdep/unix/krt.c      | 15 +++++++++++----
 sysdep/unix/krt.h      |  4 ++++
 5 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/doc/bird.sgml b/doc/bird.sgml
index 29e12b7a..af87d5dc 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -3454,9 +3454,8 @@ on the <cf/learn/ switch, such routes are either ignored or accepted to our
 table).

 <p>Note that routes created by OS kernel itself, namely direct routes
-representing IP subnets of associated interfaces, are not imported even with -<cf/learn/ enabled. You can use <ref id="direct" name="Direct protocol"> to
-generate these direct routes.
+representing IP subnets of associated interfaces, are imported only with
+<cf/learn all/ enabled.

 <p>If your OS supports only a single routing table, you can configure only one  instance of the Kernel protocol. If it supports multiple tables (in order to
@@ -3487,10 +3486,12 @@ channels.
     Time in seconds between two consecutive scans of the kernel routing
     table.

-    <tag><label id="krt-learn">learn <m/switch/</tag>
+    <tag><label id="krt-learn">learn [<m/all/]</tag>
     Enable learning of routes added to the kernel routing tables by other      routing daemons or by the system administrator. This is possible only on
-    systems which support identification of route authorship.
+    systems which support identification of route authorship. By default, routes +    created by kernel (marked as "proto kernel") are not imported. Use <m/all/
+    option to import these routes.

     <tag><label id="krt-kernel-table">kernel table <m/number/</tag>
     Select which kernel table should this particular instance of the Kernel
diff --git a/sysdep/linux/netlink.c b/sysdep/linux/netlink.c
index 1af78766..29446cab 100644
--- a/sysdep/linux/netlink.c
+++ b/sysdep/linux/netlink.c
@@ -1598,7 +1598,7 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)

     case RTPROT_KERNEL:
       krt_src = KRT_SRC_KERNEL;
-      return;
+      break;

     case RTPROT_BIRD:
       if (!s->scan)
diff --git a/sysdep/unix/krt.Y b/sysdep/unix/krt.Y
index 95b54d65..f3eb1393 100644
--- a/sysdep/unix/krt.Y
+++ b/sysdep/unix/krt.Y
@@ -32,6 +32,7 @@ CF_DECLS
 CF_KEYWORDS(KERNEL, PERSIST, SCAN, TIME, LEARN, DEVICE, ROUTES, GRACEFUL, RESTART, KRT_SOURCE, KRT_METRIC, MERGE, PATHS)
 CF_KEYWORDS(INTERFACE, PREFERRED)

+%type <i> kern_learn
 %type <i> kern_mp_limit

 CF_GRAMMAR
@@ -48,6 +49,10 @@ kern_proto_start: proto_start KERNEL {
 kern_proto: kern_proto_start proto_name '{' ;
 kern_proto: kern_proto kern_item ';' ;

+kern_learn:
+ bool { $$ = $1 ? KRT_LEARN_SOME : KRT_LEARN_NONE; }
+ | ALL { $$ = KRT_LEARN_ALL; }
+
 kern_mp_limit:
    /* empty */ { $$ = KRT_DEFAULT_ECMP_LIMIT; }
  | LIMIT expr  { $$ = $2; if (($2 <= 0) || ($2 > 255)) cf_error("Merge paths limit must be in range 1-255"); }
@@ -61,7 +66,7 @@ kern_item:
       /* Scan time of 0 means scan on startup only */
       THIS_KRT->scan_time = $3 S_;
    }
- | LEARN bool {
+ | LEARN kern_learn {
       THIS_KRT->learn = $2;
 #ifndef KRT_ALLOW_LEARN
       if ($2)
diff --git a/sysdep/unix/krt.c b/sysdep/unix/krt.c
index 9f95247f..3288fd0c 100644
--- a/sysdep/unix/krt.c
+++ b/sysdep/unix/krt.c
@@ -638,13 +638,14 @@ krt_got_route(struct krt_proto *p, rte *e, s8 src)

 #ifdef KRT_ALLOW_LEARN
   switch (src)
-    {
-    case KRT_SRC_KERNEL:
-      goto ignore;
-
+    {
     case KRT_SRC_REDIRECT:
       goto delete;

+    case KRT_SRC_KERNEL:
+      if (KRT_CF->learn != KRT_LEARN_ALL)
+        goto ignore;
+      // fall through
     case  KRT_SRC_ALIEN:
       if (KRT_CF->learn)
     krt_learn_scan(p, e);
@@ -780,6 +781,12 @@ krt_got_route_async(struct krt_proto *p, rte *e, int new, s8 src)
       break;

 #ifdef KRT_ALLOW_LEARN
+  case KRT_SRC_KERNEL:
+      if (KRT_CF->learn == KRT_LEARN_ALL)
+    {
+      krt_learn_async(p, e, new);
+    }
+  break;
     case KRT_SRC_ALIEN:
       if (KRT_CF->learn)
     {
diff --git a/sysdep/unix/krt.h b/sysdep/unix/krt.h
index 18a206e6..694ebd34 100644
--- a/sysdep/unix/krt.h
+++ b/sysdep/unix/krt.h
@@ -27,6 +27,10 @@ struct kif_proto;
 #define KRT_REF_SEEN    0x1    /* Seen in table */
 #define KRT_REF_BEST    0x2    /* Best in table */

+#define KRT_LEARN_NONE 0 /* Don't learn */
+#define KRT_LEARN_SOME 1 /* Learn some routes (excluding RTPROT_KERNEL) */
+#define KRT_LEARN_ALL 2 /* Learn all routes */
+
 /* Whenever we recognize our own routes, we allow learing of foreign routes */

 #ifdef CONFIG_SELF_CONSCIOUS

--
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.

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