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[Openvpn-devel,v8] dco_linux: extend netlink error cb with extra info

Message ID 20250127122101.10273-1-gert@greenie.muc.de
State Superseded
Headers show
Series [Openvpn-devel,v8] dco_linux: extend netlink error cb with extra info | expand

Commit Message

Gert Doering Jan. 27, 2025, 12:21 p.m. UTC 
From: Antonio Quartulli <antonio@mandelbit.com>

A netlink error may contain more specific attributes: i.e.
missing attributes or missing neted objects.

Parse and print this information too.

Note that we are re-defining some enum entries that exist
in netlink.h starting with linux-6.1.
Since we do support distros not shipping an up-to-date
netlink.h, we had to re-define the entries we need for
this patch.

Change-Id: I9e27ff335d892429334137d028f8503da4e4ca5b
Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/841
This mail reflects revision 8 of this Change.

Acked-by according to Gerrit (reflected above):
Frank Lichtenheld <frank@lichtenheld.com>
diff mbox series

Patch

diff --git a/src/openvpn/dco_linux.c b/src/openvpn/dco_linux.c
index b038382..abfd3b4 100644
--- a/src/openvpn/dco_linux.c
+++ b/src/openvpn/dco_linux.c
@@ -291,6 +291,25 @@ 
     return NL_SKIP;
 }
 
+/* The following enum members exist in netlink.h since linux-6.1.
+ * However, some distro we support still ship an old header, thus
+ * failing the OpenVPN compilation.
+ *
+ * For the time being we add the needed defines manually.
+ * We will drop this definition once we stop supporting those old
+ * distros.
+ *
+ * @NLMSGERR_ATTR_MISS_TYPE: type of a missing required attribute,
+ *  %NLMSGERR_ATTR_MISS_NEST will not be present if the attribute was
+ *  missing at the message level
+ * @NLMSGERR_ATTR_MISS_NEST: offset of the nest where attribute was missing
+ */
+enum ovpn_nlmsgerr_attrs {
+    OVPN_NLMSGERR_ATTR_MISS_TYPE = 5,
+    OVPN_NLMSGERR_ATTR_MISS_NEST = 6,
+    OVPN_NLMSGERR_ATTR_MAX = 6,
+};
+
 /* This function is used as error callback on the netlink socket.
  * When something goes wrong and the kernel returns an error, this function is
  * invoked.
@@ -330,7 +349,7 @@ 
     attrs = (void *)((unsigned char *)nlh + ack_len);
     len -= ack_len;
 
-    nla_parse(tb_msg, NLMSGERR_ATTR_MAX, attrs, len, NULL);
+    nla_parse(tb_msg, OVPN_NLMSGERR_ATTR_MAX, attrs, len, NULL);
     if (tb_msg[NLMSGERR_ATTR_MSG])
     {
         len = strnlen((char *)nla_data(tb_msg[NLMSGERR_ATTR_MSG]),
@@ -339,6 +358,18 @@ 
             (char *)nla_data(tb_msg[NLMSGERR_ATTR_MSG]));
     }
 
+    if (tb_msg[OVPN_NLMSGERR_ATTR_MISS_NEST])
+    {
+        msg(M_WARN, "kernel error: missing required nesting type %u\n",
+            nla_get_u32(tb_msg[OVPN_NLMSGERR_ATTR_MISS_NEST]));
+    }
+
+    if (tb_msg[OVPN_NLMSGERR_ATTR_MISS_TYPE])
+    {
+        msg(M_WARN, "kernel error: missing required attribute type %u\n",
+            nla_get_u32(tb_msg[OVPN_NLMSGERR_ATTR_MISS_TYPE]));
+    }
+
     return NL_STOP;
 }