svn commit: r317755 - head/sbin/ifconfig

[Ian Lepore]

On Wed, 2017-05-03 at 14:07 -0400, Ryan Stone wrote:
> On Wed, May 3, 2017 at 1:39 PM, Ryan Stone <rysto32 at gmail.com> wrote:
> 
> > 
> > 
> > 
> > On Wed, May 3, 2017 at 1:21 PM, Alan Somers <asomers at freebsd.org> wrote:
> > 
> > > 
> > > Author: asomers
> > > Date: Wed May  3 17:21:01 2017
> > > New Revision: 317755
> > > URL: https://svnweb.freebsd.org/changeset/base/317755
> > > 
> > > Log:
> > >   Various Coverity fixes in ifconfig(8)
> > > 
> > >   * Exit early if kldload(2) fails (1011259). This is the only change that
> > >     affects ifconfig's behavior.
> > > 
> > > 
> > Please revert this ASAP.  kldload is expected to fail for a number of
> > benign reasons and this change is likely to prevent any network
> > configuration from being applied to systems, breaking remote access.
> > 
> > 
> It's been pointed out to me off-list that the situation is not quite as
> dire as I had originally believed.  The ifconfig code in question already
> searches to check if the module in question is loaded before calling
> kldload.  However, there is at least one driver (mlx4_en) that does not
> follow the "if_" kld module naming convention that this code depends
> on, so this change will make it impossible to apply configuration to
> mlx4_en interfaces.  Additionally, it is possible that other drivers use
> the naming convention for their kld file but not for the module declared in
> the C code, in which case this change would also break configuration of
> those interfaces.
> 
> jhb@ suggests that ifconfig should only attempt to load a module if the
> interface doesn't already exist, by calling if_nametoindex to check for the
> existence of the interface.  That seems to be a reasonable fix for me, but
> in the interest of not breaking users' networking configuration
> (potentially making it impossible to fix a remote machine), I'd recommend
> that the part of the change that checks the return code from kldload() be
> reverted while a fix for this issue is worked on.

It should be noted that the existing code uses if_nametoindex()
immediately after ifmaybeload() returns, and handles errors
accordingly.  I.e., there wasn't really anything wrong with the code as
originally written/structured.

-- Ian