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[ Upstream commit 1d99aa4ed7 ]
In nested arrays don't require that the intermediate attribute
type should be a valid attribute type, it might just be zero
or an incrementing index, it is often not even used.
See include/net/netlink.h about NLA_NESTED_ARRAY:
> The difference to NLA_NESTED is the structure:
> NLA_NESTED has the nested attributes directly inside
> while an array has the nested attributes at another
> level down and the attribute types directly in the
> nesting don't matter.
Example based on 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
> ...
> ...
Previous the check required that the nested type was valid
in the parent attribute set, which in this case resolves to
WGDEVICE_A_UNSPEC, which is YNL_PT_REJECT, and it took the
early exit and returned YNL_PARSE_CB_ERROR.
This patch renames the old nl_attr_validate() to
__nl_attr_validate(), and creates a new inline function
nl_attr_validate() to mimic the old one.
The new __nl_attr_validate() takes the attribute type as an
argument, so we can use it to validate attributes of a
nested attribute, in the context of the parents attribute
type, which in the above case is generated as:
[WGDEVICE_A_PEERS] = {
.name = "peers",
.type = YNL_PT_NEST,
.nest = &wireguard_wgpeer_nest,
},
__nl_attr_validate() only checks if the attribute length
is plausible for a given attribute type, so the .nest in
the above example is not used.
As the new inline function needs to be defined after
ynl_attr_type(), then the definitions are moved down,
so we avoid a forward declaration of ynl_attr_type().
Some other examples are NL80211_BAND_ATTR_FREQS (nest) and
NL80211_ATTR_SUPPORTED_COMMANDS (u32) both in nl80211-user.c
$ make -C tools/net/ynl/generated nl80211-user.c
Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250915144301.725949-7-ast@fiberby.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>