On 9/21/23 10:23, Johannes Nixdorf wrote:

On Wed, Sep 20, 2023 at 01:46:02PM +0300, Nikolay Aleksandrov wrote:

quoted

On 9/19/23 11:12, Johannes Nixdorf wrote:

quoted

Set any new attributes added to br_policy to be parsed strictly, to
prevent userspace from passing garbage.

Signed-off-by: Johannes Nixdorf <redacted>
---
   net/bridge/br_netlink.c | 2 ++
   1 file changed, 2 insertions(+)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 10f0d33d8ccf..505683ef9a26 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c

@@ -1229,6 +1229,8 @@ static size_t br_port_get_slave_size(const struct net_device *brdev,
   }
   static const struct nla_policy br_policy[IFLA_BR_MAX + 1] = {
+	[IFLA_BR_UNSPEC]	= { .strict_start_type =
+				    IFLA_BR_MCAST_QUERIER_STATE + 1 },
   	[IFLA_BR_FORWARD_DELAY]	= { .type = NLA_U32 },
   	[IFLA_BR_HELLO_TIME]	= { .type = NLA_U32 },
   	[IFLA_BR_MAX_AGE]	= { .type = NLA_U32 },

instead of IFLA_BR_MCAST_QUERIER_STATE + 1, why not move around the patch
and just use the new attribute name?
These are uapi, they won't change.

I wanted to avoid having a state between the two commits where the new
attributes are already added, but not yet strictly verified. Otherwise
they would present a slightly different UAPI at that one commit boundary
than after this commit.

That's not really a problem, the attribute is the same.

This is also not the only place in the kernel where strict_start_type
is specified that way. See e.g. commit c00041cf1cb8 ("net: bridge: Set
strict_start_type at two policies"), even though that seems mostly be
done to turn on strict_start_type preemtively, not in the same series
that adds the new attribute.

Please, just use the new attribute to be more explicit where the strict 
parsing starts.

Thanks,
  Nik