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" 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 --- 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 Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html