On Wed, Aug 23, 2023 at 03:59:39PM +0200, Stefano Brivio wrote:
On Wed, 23 Aug 2023 14:53:27 +0100
"Richard W.M. Jones" <rjones(a)redhat.com> wrote:
> On Wed, Aug 23, 2023 at 03:48:44PM +0200, Stefano Brivio wrote:
> > The hard link trick didn't actually fix the issue with SELinux file
> > contexts properly: as opposed to symbolic links, SELinux now
> > correctly associates types to the labels that are set -- except that
> > those labels are now shared, so we can end up (depending on how
> > rpm(8) extracts the archives) with /usr/bin/passt having a
> > pasta_exec_t context.
> >
> > This got rather confusing as running restorecon(8) seemed to fix up
> > labels -- but that's simply toggling between passt_exec_t and
> > pasta_exec_t for both links, because each invocation will just "fix"
> > the file with the mismatching context.
> >
> > Replace the hard links with copies. AppArmor's attachment, instead,
> > works with hard links, and if there's no LSM, we can keep symbolic
> > links, so keep symbolic links in the Makefile.
> >
> > With copies, rpmbuild(8) will warn about duplicate Build-IDs in the
> > same package. Mangle them in pasta binaries by summing one to the
> > last byte, modulo one byte, using xxd (provided by vim-common) and
> > disable the automatic rehashing by find-debuginfo(1) -- we already
> > have per-release Build-IDs thanks to $VERSION passed on 'make'.
>
> Right, this ^ was going to be my comment. RPM doesn't like having two
> identical copies of a file.
In which other way, though? cpio(1) is fine with it, and I tried to
install the package on both ext4 and xfs -- the only warning I got was
the (semi-reasonable) one from rpmbuild about duplicate Build-IDs.
I'm fairly sure I've seen an error when you have two identical files;
it might only happen in Koji. Anyway, hacking the binary is surely
wrong, but let's hear the opinions of the Fedora / SELinux developers.
Rich.
> Hacking the binary to "fix" the problem doesn't
sound like a solution.
>
> I'm CC-ing Fedora-devel-list to find out we can properly fix this issue.
>
> Rich.
>
> > Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
> > ---
> > contrib/fedora/passt.spec | 27 ++++++++++++++++++++++-----
> > 1 file changed, 22 insertions(+), 5 deletions(-)
> >
> > diff --git a/contrib/fedora/passt.spec b/contrib/fedora/passt.spec
> > index d0c6895..51bf5a8 100644
> > --- a/contrib/fedora/passt.spec
> > +++ b/contrib/fedora/passt.spec
> > @@ -9,6 +9,10 @@
> >
> > %global git_hash {{{ git_head }}}
> > %global selinuxtype targeted
> > +# Different Build-IDs for passt and pasta: don't let find-debuginfo touch
them
> > +%undefine _unique_build_ids
> > +%global _no_recompute_build_ids 1
> > +
> >
> > Name: passt
> > Version: {{{ git_version }}}
> > @@ -19,7 +23,7 @@ Group: System Environment/Daemons
> > URL:
https://passt.top/
> > Source:
https://passt.top/passt/snapshot/passt-%{git_hash}.tar.xz
> >
> > -BuildRequires: gcc, make, checkpolicy, selinux-policy-devel
> > +BuildRequires: gcc, make, checkpolicy, selinux-policy-devel, binutils,
vim-common
> > Requires: (%{name}-selinux = %{version}-%{release} if
selinux-policy-%{selinuxtype})
> >
> > %description
> > @@ -56,15 +60,28 @@ This package adds SELinux enforcement to passt(1) and
pasta(1).
> > %install
> >
> > %make_install DESTDIR=%{buildroot} prefix=%{_prefix} bindir=%{_bindir}
mandir=%{_mandir} docdir=%{_docdir}/%{name}
> > -# The Makefile creates symbolic links for pasta, but we need hard links for
> > +# The Makefile creates symbolic links for pasta, but we need actual copies
for
> > # SELinux file contexts to work as intended. Same with pasta.avx2 if present.
> > -ln -f %{buildroot}%{_bindir}/passt %{buildroot}%{_bindir}/pasta
> > +#
> > +# To avoid duplicate Build-IDs in the same package, we increase the last byte
of
> > +# the value for pasta binaries by one (modulo one byte). Note that we already
> > +# have differentiated Build-IDs per release, courtesy of $VERSION, so we
don't
> > +# need find-debuginfo(1) to recalculate them.
> > +rm %{buildroot}%{_bindir}/pasta
> > +objcopy --dump-section .note.gnu.build-id=%{buildroot}/build_id
%{buildroot}%{_bindir}/passt
> > +printf '\x'$(printf %02x $(( ( 0x$(xxd -ps -s 35
%{buildroot}/build_id) + 1 ) % 0xff )) ) | dd of=%{buildroot}/build_id seek=35 bs=1
count=1 conv=notrunc
> > +objcopy --update-section .note.gnu.build-id=%{buildroot}/build_id
%{buildroot}%{_bindir}/passt %{buildroot}%{_bindir}/pasta
> > +rm %{buildroot}/build_id
> > +
> > %ifarch x86_64
> > -ln -f %{buildroot}%{_bindir}/passt.avx2 %{buildroot}%{_bindir}/pasta.avx2
> > +rm %{buildroot}%{_bindir}/pasta.avx2
> > +objcopy --dump-section .note.gnu.build-id=%{buildroot}/build_id
%{buildroot}%{_bindir}/passt.avx2
> > +printf '\x'$(printf %02x $(( ( 0x$(xxd -ps -s 35
%{buildroot}/build_id) + 1 ) % 0xff )) ) | dd of=%{buildroot}/build_id seek=35 bs=1
count=1 conv=notrunc
> > +objcopy --update-section .note.gnu.build-id=%{buildroot}/build_id
%{buildroot}%{_bindir}/passt.avx2 %{buildroot}%{_bindir}/pasta.avx2
> > +rm %{buildroot}/build_id
> >
> > ln -sr %{buildroot}%{_mandir}/man1/passt.1
%{buildroot}%{_mandir}/man1/passt.avx2.1
> > ln -sr %{buildroot}%{_mandir}/man1/pasta.1
%{buildroot}%{_mandir}/man1/pasta.avx2.1
> > -install -p -m 755 %{buildroot}%{_bindir}/passt.avx2
%{buildroot}%{_bindir}/pasta.avx2
> > %endif
> >
> > pushd contrib/selinux
> > --
> > 2.39.2
--
Stefano
--
Richard Jones, Virtualization Group, Red Hat
http://people.redhat.com/~rjones
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