[PATCH net-next v2] openvswitch: Stricter validation for the userspace action

[PATCH net-next v2] openvswitch: Stricter validation for the userspace action

[Eelco Chaudron]

This change enhances the robustness of validate_userspace() by ensuring
that all Netlink attributes are fully contained within the parent
attribute. The previous use of nla_parse_nested_deprecated() could
silently skip trailing or malformed attributes, as it stops parsing at
the first invalid entry.

By switching to nla_parse_deprecated_strict(), we make sure only fully
validated attributes are copied for later use.

Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
---
v2: Changed commit message based on Ilya's feedback.
---
 net/openvswitch/flow_netlink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index 518be23e48ea..ad64bb9ab5e2 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -3049,7 +3049,8 @@ static int validate_userspace(const struct nlattr *attr)
 	struct nlattr *a[OVS_USERSPACE_ATTR_MAX + 1];
 	int error;
 
-	error = nla_parse_nested_deprecated(a, OVS_USERSPACE_ATTR_MAX, attr,
+	error = nla_parse_deprecated_strict(a, OVS_USERSPACE_ATTR_MAX,
+					    nla_data(attr), nla_len(attr),
 					    userspace_policy, NULL);
 	if (error)
 		return error;
-- 
2.47.1

Re: [PATCH net-next v2] openvswitch: Stricter validation for the userspace action

[Simon Horman]

On Mon, May 12, 2025 at 10:08:24AM +0200, Eelco Chaudron wrote:
> This change enhances the robustness of validate_userspace() by ensuring
> that all Netlink attributes are fully contained within the parent
> attribute. The previous use of nla_parse_nested_deprecated() could
> silently skip trailing or malformed attributes, as it stops parsing at
> the first invalid entry.
> 
> By switching to nla_parse_deprecated_strict(), we make sure only fully
> validated attributes are copied for later use.
> 
> Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
> ---
> v2: Changed commit message based on Ilya's feedback.

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net-next v2] openvswitch: Stricter validation for the userspace action

[Ilya Maximets]

On 5/12/25 10:08 AM, Eelco Chaudron wrote:
> This change enhances the robustness of validate_userspace() by ensuring
> that all Netlink attributes are fully contained within the parent
> attribute. The previous use of nla_parse_nested_deprecated() could
> silently skip trailing or malformed attributes, as it stops parsing at
> the first invalid entry.
> 
> By switching to nla_parse_deprecated_strict(), we make sure only fully
> validated attributes are copied for later use.

Just to re-iterate for anyone reading this thread, copying non-validated
attributes is not a problem as they will be ignored during execution.

The change looks fine to me, thanks!

Acked-by: Ilya Maximets <i.maximets@ovn.org>

Re: [PATCH net-next v2] openvswitch: Stricter validation for the userspace action

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 12 May 2025 10:08:24 +0200 you wrote:
> This change enhances the robustness of validate_userspace() by ensuring
> that all Netlink attributes are fully contained within the parent
> attribute. The previous use of nla_parse_nested_deprecated() could
> silently skip trailing or malformed attributes, as it stops parsing at
> the first invalid entry.
> 
> By switching to nla_parse_deprecated_strict(), we make sure only fully
> validated attributes are copied for later use.
> 
> [...]

Here is the summary with links:
  - [net-next,v2] openvswitch: Stricter validation for the userspace action
    https://git.kernel.org/netdev/net-next/c/88906f559541

You are awesome, thank you!
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