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Re: RT linker, rpath and security





On 12/05/23 07:43, tlaronde%polynum.com@localhost 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



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