On Sat, 6 Sep 2025 13:22:01 +0000 Asbjørn Sloth Tønnesen wrote:

quoted

I don't understand, please provide more details.
This is an ArrayNest, right?

[ARRAY-ATTR]
   [ENTRY]
     [MEMBER1]
     [MEMBER2]
   [ENTRY]
     [MEMBER1]
     [MEMBER2]

Which level are you saying doesn't matter?
If entry is a nest it must be a valid nest.
What the comment you're quoting is saying is that the nla_type of ENTRY
doesn't matter.  

I will expand this in v2, but the gist of it is that this is part of the
"split attribute counting, and later allocating an array to hold them" code.

The check that I remove for nested arrays, is an early exit during the
counting phase. Later in the allocation and parse phase it validates the
nested payload.

In include/uapi/linux/wireguard.h:
 > WGDEVICE_A_PEERS: NLA_NESTED
 >   0: NLA_NESTED
 >     WGPEER_A_PUBLIC_KEY: NLA_EXACT_LEN, len WG_KEY_LEN
 >     [..]
 >   0: NLA_NESTED
 >     ...
 >   ...  

The current check requires that the nested type is valid in the nested
attribute set, which in this case resolves to WGDEVICE_A_UNSPEC, which is
YNL_PT_REJECT, and it takes the early exit and returns YNL_PARSE_CB_ERROR.

I see your point now. We're validating ENTRY as an attribute in the
parent attribute set, but it's just a meaningless id.

I think we need more fixing here. The real parsing loop will only
validate what's _inside_ the [MEMBER]. Which doesn't matter all
that much to nests, but look at what happens if subtype is a scalar.
We'll just call ynl_attr_get_u32(), type is never really validate.

I think we need this, and make the codegen feed in the ARRAY-ATTR type
to validate ENTRY?

diff --git a/tools/net/ynl/lib/ynl.c b/tools/net/ynl/lib/ynl.c
index 2a169c3c0797..e43167398c69 100644
--- a/tools/net/ynl/lib/ynl.c
+++ b/tools/net/ynl/lib/ynl.c

@@ -360,15 +360,15 @@ static int ynl_cb_done(const struct nlmsghdr *nlh, struct ynl_parse_arg *yarg)
 
 /* Attribute validation */
 
-int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr)
+int __ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr,
+			unsigned int type)
 {
 	const struct ynl_policy_attr *policy;
-	unsigned int type, len;
 	unsigned char *data;
+	unsigned int len;
 
 	data = ynl_attr_data(attr);
 	len = ynl_attr_data_len(attr);
-	type = ynl_attr_type(attr);
 	if (type > yarg->rsp_policy->max_attr) {
 		yerr(yarg->ys, YNL_ERROR_INTERNAL,
 		     "Internal error, validating unknown attribute");

@@ -450,6 +450,11 @@ int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr)
 	return 0;
 }
 
+int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr)
+{
+	return __ynl_attr_validate(yarg, attr, ynl_attr_type(attr));
+}
+
 int ynl_submsg_failed(struct ynl_parse_arg *yarg, const char *field_name,
 		      const char *sel_name)
 {