Re: [PATCH net-next v10 1/6] netlink: specs: rt-addr: fix the type of target-netnsid

[netdev-bot+sashiko@kernel.org]

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Low priority / nit picks for your consideration:

- [Low] Commit "netlink: specs: rt-addr: fix the type of target-netnsid"
  fixes a real defect in Documentation/netlink/specs/rt-addr.yaml but…

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netlink: specs: rt-addr: fix the type of target-netnsid

This patch changes the type of the target-netnsid attribute in
rt-addr.yaml from binary to s32. The kernel parses IFA_TARGET_NETNSID
as NLA_S32, and rt-link.yaml already declares its own target-netnsid
as s32.

> The kernel parses IFA_TARGET_NETNSID as NLA_S32 and rt-link.yaml
> declares its target-netnsid as s32, but rt-addr.yaml has it as binary.
>
> Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
> Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>

[Severity: Low]
Should this have a Fixes: tag?

The binary type on target-netnsid goes back to the commit that first
added the spec. A later rename to target-netnsid kept the type as it
was. On the kernel side, IFA_TARGET_NETNSID has always been s32. It
is NLA_S32 in ifa_ipv4_policy in net/ipv4/devinet.c and in the IPv6
policy in net/ipv6/addrconf.c, and it is written with nla_put_s32()
and read with nla_get_s32().

Python YNL is affected on any tree without this fix. When an integer
is passed for target-netnsid, YnlFamily._add_attr() in
tools/net/ynl/pyynl/lib/ynl.py takes the binary branch and raises:

    raise YnlException(f'Unknown type for binary attribute, value: {value}')

Replies that carry the attribute are also decoded as raw bytes, not
as a signed int.

Would something like this be appropriate?

Fixes: dfb0f7d9d979 ("doc/netlink: Add spec for rt addr messages")

> diff --git a/Documentation/netlink/specs/rt-addr.yaml b/Documentation/netlink/specs/rt-addr.yaml
> index 0ecbd24c890c..17ead2203451 100644
> --- a/Documentation/netlink/specs/rt-addr.yaml
> +++ b/Documentation/netlink/specs/rt-addr.yaml
> @@ -119,7 +119,7 @@ attribute-sets:
>          type: u32
>        -
>          name: target-netnsid
> -        type: binary
> +        type: s32
>        -
>          name: proto
>          type: u8

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Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261007115821.11332-1-sigefriedhyy%40gmail.com