svn commit: r228843 - head/contrib/telnet/libtelnet head/crypto/heimdal/appl/telnet/libtelnet head/include head/lib/libc/gen head/lib/libc/iconv head/lib/libc/include head/lib/libc/net head/libexec...

[Alexander Kabaev]

On Fri, 23 Dec 2011 19:51:43 +0200
Kostik Belousov <kostikbel at gmail.com> wrote:

> On Fri, Dec 23, 2011 at 12:06:44PM -0500, Alexander Kabaev wrote:
> > On Fri, 23 Dec 2011 11:22:34 -0500
> > John Baldwin <jhb at freebsd.org> wrote:
> > 
> > > On Friday, December 23, 2011 10:58:46 am John Baldwin wrote:
> > > > On Friday, December 23, 2011 10:00:38 am Colin Percival wrote:
> > > > > Author: cperciva
> > > > > Date: Fri Dec 23 15:00:37 2011
> > > > > New Revision: 228843
> > > > > URL: http://svn.freebsd.org/changeset/base/228843
> > > > > 
> > > > > Log:
> > > > >   Fix a problem whereby a corrupt DNS record can cause named
> > > > > to crash. [11:06] 
> > > > >   Add an API for alerting internal libc routines to the
> > > > > presence of "unsafe" paths post-chroot, and use it in ftpd.
> > > > > [11:07]
> > > > 
> > > > Eh, the whole libc_dlopen() thing looks like a gross hack (and
> > > > who came up with that weird symbol name for a public API????).
> > > > Is it really even needed given the other fix to have ftpd drop
> > > > privilege before execing a helper program?  I guess the main
> > > > reason I don't like it is it doesn't do anything to address the
> > > > more general problem.  I would have expected instead something
> > > > to restrict dlopen() entirely including from other libraries
> > > > than just libc in certain circumstances.
> > > 
> > > At the very least if we feel that the libc_dlopen() thing is a
> > > temporary band-aid, we should move the new symbols into the
> > > private namespace so we can remove them once the better fix is in
> > > rather than being required to support them forever.
> libc_dlopen() is not exposed.
> The __FreeBSD_libc_enter_restricted_mode() is, and its name is ugly
> exactly to note the ugly intent. I do not see how the symbol can go
> int FBSDprivate_1.0 when it was supposed to be used by third-party
> applications.
> 
> Putting this hack into rtld itself IMO has to wide consequences.
> For libc, we can enumerate the points that stop work after the call,
> but for the generic applications the consequences are undefined.
> > > 
> > > -- 
> > > John Baldwin
> > 
> > Pardon for not catching that when I had a chance to influence the
> > outcome, but I would like to voice my support to tucking the
> > ugliness into private version namespace.
> > 
> > -- 
> > Alexander Kabaev
> 
Putting symbol into official namespace implies that we are willing to
provide and maintain it forever, which I do not think was the intent
for the function in question. FBSD_PRIVATE says nothing about who
should and should not link to it, only the level of API stability one
has to expect in the end. If/when we have better security mechanisms
(capsicum?) available to users by default, this should be ripped out
with extreme prejudice.

-- 
Alexander Kabaev
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