> @@ -2061,6 +2174,9 @@ static int tun_set_iff(struct net *net, struct file
> *file, struct ifreq *ifr)
> if (tfile->detached)
> return -EINVAL;
>
> + if ((ifr->ifr_flags & IFF_NAPI_FRAGS) && !capable(CAP_NET_ADMIN))
> + return -EPERM;
> +
This should perhaps be moved into the !dev branch, directly below the
ns_capable check.
> dev = __dev_get_by_name(net, ifr->ifr_name);
> if (dev) {
> if (ifr->ifr_flags & IFF_TUN_EXCL)
> @@ -2185,6 +2301,9 @@ static int tun_set_iff(struct net *net, struct file
> *file, struct ifreq *ifr)
> tun->flags = (tun->flags & ~TUN_FEATURES) |
> (ifr->ifr_flags & TUN_FEATURES);
>
> + if (!(tun->flags & IFF_NAPI) || (tun->flags & TUN_TYPE_MASK) !=
> IFF_TAP)
> + tun->flags = tun->flags & ~IFF_NAPI_FRAGS;
> +
Similarly, this check only need to be performed in that branch.
Instead of reverting to non-frags mode, a tun_set_iff with the wrong
set of flags should probably fail hard.
