Re: RT linker, rpath and security

On 12/05/23 07:43, [email protected] wrote:
> Le Thu, May 11, 2023 at 09:45:07AM -0400, Greg Troxel a écrit :
> ...
> 
> $ readelf -d /usr/pkg/sbin/visudo | egrep "NEEDED|RPATH"
> 
>   0x0000000000000001 (NEEDED)             Shared library: [libc.so.12]
>   0x000000000000000f (RPATH)              Library rpath: [/usr/pkg/lib]
> 
> visudo depends only on the system libc (I'm on NetBSD 9.3) and
> loads the dynshared /usr/pkg/libexec/sudo_noexec.so (the full path is
> given) but still there is a rpath registered pointing to /usr/pkg/lib.
> 
> If a package would be installing a libc.so.12 under /usr/pkg/lib, this
> one will be used instead of the system one.

I can see two issues here:

1) Some pkgsrc binaries are installed with /usr/pkg/lib in their rpath 
when they don't need it. I'm going to guess that pkgsrc always puts 
/usr/pkg/lib on every binary's rpath. Allowing packages to opt out of 
this behaviour for individual binaries should be possible, but I don't 
think it's worth the trouble.

2) Packages can shadow shared libraries in /usr/lib. (Assuming the 
library rpath has priority over /usr/lib, it probably does but I haven't 
checked.) We already check the PLIST of packages that are about to be 
installed for files that will conflict with ones that are already 
installed. We could enhance this to check for shadowing of shared 
libraries in /usr/lib and then issue an error or a warning.

Cheers,
Lloyd