SO_PEERSEC protections in sk_getsockopt()?

[Paul Moore]

On Wed, Oct 5, 2022 at 4:44 PM Paul Moore <paul at paul-moore.com> wrote:
>
> Hi Martin,
>
> In commit 4ff09db1b79b ("bpf: net: Change sk_getsockopt() to take the
> sockptr_t argument") I see you wrapped the getsockopt value/len
> pointers with sockptr_t and in the SO_PEERSEC case you pass the
> sockptr_t:user field to avoid having to update the LSM hook and
> implementations.  I think that's fine, especially as you note that
> eBPF does not support fetching the SO_PEERSEC information, but I think
> it would be good to harden this case to prevent someone from calling
> sk_getsockopt(SO_PEERSEC) with kernel pointers.  What do you think of
> something like this?
>
>   static int sk_getsockopt(...)
>   {
>     /* ... */
>     case SO_PEERSEC:
>       if (optval.is_kernel || optlen.is_kernel)
>         return -EINVAL;
>       return security_socket_getpeersec_stream(...);
>     /* ... */
>   }

Any thoughts on this Martin, Alexei?  It would be nice to see this
fixed soon ...

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