svn commit: r257696 - in head: libexec/rbootd share/man/man9 sys/compat/svr4 sys/net sys/sys

[Peter Wemm]

On 11/5/13, 2:18 PM, John Baldwin wrote:
> On Tuesday, November 05, 2013 3:42:17 pm Gleb Smirnoff wrote:
>>    John,
>>
>> On Tue, Nov 05, 2013 at 02:47:52PM -0500, John Baldwin wrote:
>> J> On Tuesday, November 05, 2013 2:29:04 pm Gleb Smirnoff wrote:
>> J> > On Tue, Nov 05, 2013 at 11:56:09AM -0500, John Baldwin wrote:
>> J> > J> On Tuesday, November 05, 2013 5:29:48 am Gleb Smirnoff wrote:
>> J> > J> > Author: glebius
>> J> > J> > Date: Tue Nov  5 10:29:47 2013
>> J> > J> > New Revision: 257696
>> J> > J> > URL: http://svnweb.freebsd.org/changeset/base/257696
>> J> > J> >
>> J> > J> > Log:
>> J> > J> >   Drop support for historic ioctls and also undefine them, so that code
>> J> > J> >   that checks their presence via ifdef, won't use them.
>> J> > J>
>> J> > J> Most of these are COMPAT_43, but one appears to be a 9.x ioctl?  If that's the
>> J> > J> case it's implementation should probably stick around under appropriate
>> J> > J> COMPAT_FREEBSD<x> macros.  It looks like it goes all the way back to 4.4BSD,
>> J> > J> so at least COMPAT_FREEBSD4 and later should define the implementation to
>> J> > J> preserve ABI compat for old binaries.
>> J> >
>> J> > Why should we support such broken configurations as running new kernel and
>> J> > ancient core base system utilities? The efforts to keep this are much more
>> J> > expensive, then yields.
>> J>
>> J> Is this ioctl only ever used by ifconfig and not suitable for public consumption?
>> J> If so, then I think removing it is fine.  However, it's not clear that this is
>> J> the case from the commit, and it's good to make sure it is really the case.
>> J>
>> J> It might be nice to hide ioctls we think are internal under some #ifdef that tools
>> J> like ifconfig #define to expose them so we are more explicit about which ioctls
>> J> are purely internal, etc.
>>
>> Well, it isn't hidden and actually some applications as zebra/quagga can use it.
>>
>> On previous hacking session at this area, 2 years ago, I noticed that zebra/quagga
>> do use SIOCAIFADDR and it actually does better at filling sockaddrs than our
>> ifconfig :)
>>
>> I am pretty sure that no closed source, but available to wide public, application
>> that configures addresses in FreeBSD kernel exist.
>>
>> In case of open source applications, like zebra/quagga, supporting one major
>> release behind should be enough.
> Mmmm, people run older versions of binaries (even open source ones) on newer OS's
> perhaps more often than you think.   The COMPAT_43 stuff can be dropped certainly,
> but people will almost certainly do rolling upgrades where they upgrade the OS
> on their machines before they upgrade their packages.
>
This change is actually even worse than it appears. One of the key 
features that was removed was the workaround for code that doesn't know 
about sockaddr.sa_len.

eg: /usr/sbin/traceroute after the change:
# traceroute www.freebsd.org
traceroute: ifaddrlist: SIOCGIFADDR: bge0: Can't assign requested address

Hint: linux doesn't have a sa_len, so code that originates on Linux will 
no longer work.  The code glebius removed used to work around this.

This is not old binaries, this is binaries compiled *today*.

-Peter