[PATCH net-next v2] netlink: specs: fix duplicate if/then keys in netlink-raw schema

[Taylor Bates <tmbates12@gmail.com>]

Currently netlink-raw.yaml contains two if keys and two then keys in a
single mapping that enforces a "len" for "pad" members and a "len" or
"struct" for binary members.

During validation PyYAML resolves duplicate keys last-wins, so only the
binary rule survives. Pad has not been validated since commit
bf08f32c8ced ("tools/net/ynl: Add support for nested structs") added
the second if/then pair in January 2024.

None of the current specs violate this rule, but this validation should
not be parser dependent and unspecified. Strict YAML validators such as
Red Hat's VS Code YAML extension and Adrien Verge's yamllint will
reject the netlink-raw.yaml schema:

Command:
  $ yamllint Documentation/netlink/netlink-raw.yaml

Output:
  185:13    error    duplication of key "if" in mapping  (key-duplicates)
  189:13    error    duplication of key "then" in mapping  (key-duplicates)

The following invalid netlink family spec will pass validation in the
current ynl tooling:

  # SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
  ---
  name: minimal-raw
  doc: Minimal netlink-raw family for schema validation testing.
  protocol: netlink-raw
  protonum: 0

  definitions:
    -
      name: test-struct
      type: struct
      members:
        -
          name: reserved
          type: pad
          # len intentionally omitted

  attribute-sets: []

  operations:
    list: []

Signed-off-by: Taylor Bates <tmbates12@gmail.com>
---
This is a repost of patch 1 from the "netlink: fix ynl spec tooling
robustness bugs" series, reduced to this single fix as requested.

The netlink-raw spec for the Bridge VLAN family that motivated the
original series will be sent separately once this has landed.
---
Changes in v2:
- Drop patches 2/4, 3/4 and 4/4 from the series; this schema fix stands
  on its own.
- Drop the Fixes tag. This is developer tooling only and is not a bug
  that needs to reach stable. The offending commit is now cited in the
  commit message instead.
- Link to v1: https://patch.msgid.link/20260908-ynl-robustness-v1-0-f255214c0f30@gmail.com

To: Donald Hunter <donald.hunter@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
To: "David S. Miller" <davem@davemloft.net>
To: Eric Dumazet <edumazet@google.com>
To: Paolo Abeni <pabeni@redhat.com>
To: Simon Horman <horms@kernel.org>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 Documentation/netlink/netlink-raw.yaml | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/Documentation/netlink/netlink-raw.yaml b/Documentation/netlink/netlink-raw.yaml
index 4c436b59a34b..18ccfe05048a 100644
--- a/Documentation/netlink/netlink-raw.yaml
+++ b/Documentation/netlink/netlink-raw.yaml
@@ -176,20 +176,23 @@ properties:
               struct:
                 description: Name of the nested struct type.
                 type: string
-            if:
-              properties:
-                type:
-                  const: pad
-            then:
-              required: [ len ]
-            if:
-              properties:
-                type:
-                  const: binary
-            then:
-              oneOf:
-                - required: [ len ]
-                - required: [ struct ]
+            allOf:
+              -
+                if:
+                  properties:
+                    type:
+                      const: pad
+                then:
+                  required: [ len ]
+              -
+                if:
+                  properties:
+                    type:
+                      const: binary
+                then:
+                  oneOf:
+                    - required: [ len ]
+                    - required: [ struct ]
         # End genetlink-legacy
 
   attribute-sets:

---
base-commit: 043777e948807b5f335f58a0b9f5ed04bba681cf
change-id: 20260907-ynl-robustness-d62d9693cc12

Best regards,
--  
Taylor Bates <tmbates12@gmail.com>