Re: [RFC] separate SIOCGIFCONF from the rest of dev_ioctl()
flat view
From: Al Viro <viro@ZenIV.linux.org.uk>
Date: 2017-06-26 22:06:44
On Mon, Jun 26, 2017 at 10:25:14PM +0200, Johannes Berg wrote:
On Mon, 2017-06-26 at 18:40 +0100, Al Viro wrote:quoted
Only two of dev_ioctl() callers may pass SIOCGIFCONF to it. Separating that codepath from the rest of dev_ioctl() allows both to simplify dev_ioctl() itself (all other cases work with struct ifreq *) *and* seriously simplify the compat side of that beast: all it takes is passing to inet_gifconf() an extra argument - the size of individual records (sizeof(struct ifreq) or sizeof(struct compat_ifreq)). With dev_ifconf() called directly from sock_do_ioctl()/compat_dev_ifconf() that's easy to arrange.No objection from me; however, I just introduced another special case (in a bugfix for a >20yo bug ...) here: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=68dd02d19c811ca8ea60220a9d73e13b4bdad73a It would perhaps make sense to also pull that out into the caller, which could also get rid of the stupid way the #ifdef is placed in sock_ioctl(). For compat, it's already pulled out anyway, even a level up than where you're calling it for SIOCGIFCONF - might make sense to put the wext stuff into compat_sock_ioctl_trans() too.
BTW, speaking of odd ioctls - e.g. SIOCGIFMETRIC does * for AF_AX25, AF_X25, AF_IRDA, AF_NETROM, AF_ROSE: fail with -EINVAL * everything else - store 0 in ifr->ifr_metric and succeed. Is there anything special about that set of families or is it just a cut'n'paste accident? SIOCGIFNETMASK: * AF_AX25, AF_X25, AF_IRDA, AF_NETROM, AF_ROSE, AF_IPX, AF_QIPCRTR: -EINVAL * AF_INET: return ipv4 netmask associated with the interface in question. * AF_PACKET: if CONFIG_INET => as AF_INET, otherwise -ENOIOCTLCMD * everything else: -ENOTTY, as far as I can tell Again, what makes ax25 different from e.g. decnet? netmask makes no sense for either, and AFAICS in exact same way. And the set of -EINVAL ones is similar, but not identical to SIOCGIFMETRIC case... And then there's SIOCGSTAMP and friends; AFAICS, they are identical for everything that implements them, modulo differences in locking. The set of those who have those also looks fairly random...