kbuild: rpm-pkg: Restrict manual debug package creation

Commit 62089b804895 ("kbuild: rpm-pkg: Generate debuginfo package
manually") moved away from the built-in RPM machinery for generating
-debuginfo packages to a more manual way to be compatible with module
signing, as the built-in machinery strips the modules after the
installation process, breaking the signatures.

Unfortunately, prior to rpm 4.20.0, there is a bug where a custom %files
directive is ignored for a -debuginfo subpackage [1], meaning builds
using older versions of RPM (such as on RHEL9 or RHEL10) fail with:

Checking for unpackaged file(s): /usr/lib/rpm/check-files .../rpmbuild/BUILDROOT/kernel-6.19.0_dirty-1.x86_64
error: Installed (but unpackaged) file(s) found:
/debuginfo.list
/usr/lib/debug/.build-id/09/748c214974bfba1522d434a7e0a02e2fd7f29b.debug
/usr/lib/debug/.build-id/0b/b96dd9c7d3689d82e56d2e73b46f53103cc6c7.debug
/usr/lib/debug/.build-id/0e/979a2f34967c7437fd30aabb41de1f0c8b6a66.debug
...

To workaround this, restrict the manual debug info package creation
process to when it is necessary (CONFIG_MODULE_SIG=y) and possible (when
using RPM >= 4.20.0). A follow up change will restore the RPM debuginfo
creation process using a separate internal flag to allow the package to
be built in more situations, as RPM 4.20.0 is a fairly recent version
and the built-in -debuginfo generation works fine when module signing is
disabled.

Cc: [e-mail]
Fixes: 62089b804895 ("kbuild: rpm-pkg: Generate debuginfo package manually")
Link: https://github.com/rpm-software-management/rpm/commit/49f906998f3cf1f4152162ca61ac0869251c380f [1]
Reported-by: Steve French <[e-mail]>
Closes: https://lore.kernel.org/[e-mail]/
Tested-by: Stefano Garzarella <[e-mail]>
Tested-by: Steve French <[e-mail]>
Tested-by: Juergen Gross <[e-mail]>
Acked-by: Nicolas Schier <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Nathan Chancellor <[e-mail]>

scripts/package/kernel.spec

···
 against the %{version} kernel package.
 %endif
 
-%if %{with_debuginfo}
+%if %{with_debuginfo_manual}
 %package debuginfo
 Summary: Debug information package for the Linux kernel
 %description debuginfo
 This package provides debug information for the kernel image and modules from the
 %{version} package.
+%define install_mod_strip 1
 %endif
 
 %prep
···
 mkdir -p %{buildroot}/lib/modules/%{KERNELRELEASE}
 cp $(%{make} %{makeflags} -s image_name) %{buildroot}/lib/modules/%{KERNELRELEASE}/vmlinuz
 # DEPMOD=true makes depmod no-op. We do not package depmod-generated files.
-%{make} %{makeflags} INSTALL_MOD_PATH=%{buildroot} INSTALL_MOD_STRIP=1 DEPMOD=true modules_install
+%{make} %{makeflags} INSTALL_MOD_PATH=%{buildroot} %{?install_mod_strip:INSTALL_MOD_STRIP=1} DEPMOD=true modules_install
 %{make} %{makeflags} INSTALL_HDR_PATH=%{buildroot}/usr headers_install
 cp System.map %{buildroot}/lib/modules/%{KERNELRELEASE}
 cp .config %{buildroot}/lib/modules/%{KERNELRELEASE}/config
···
 	echo "%exclude /lib/modules/%{KERNELRELEASE}/build"
 } > %{buildroot}/kernel.list
 
-%if %{with_debuginfo}
+%if %{with_debuginfo_manual}
 # copying vmlinux directly to the debug directory means it will not get
 # stripped (but its source paths will still be collected + fixed up)
 mkdir -p %{buildroot}/usr/lib/debug/lib/modules/%{KERNELRELEASE}
···
 /lib/modules/%{KERNELRELEASE}/build
 %endif
 
-%if %{with_debuginfo}
+%if %{with_debuginfo_manual}
 %files -f %{buildroot}/debuginfo.list debuginfo
 %defattr (-, root, root)
 %exclude /debuginfo.list

scripts/package/mkspec

···
 echo '%define with_devel 0'
 fi
 
+# manually generate -debuginfo package
+with_debuginfo_manual=0
 # debuginfo package generation uses find-debuginfo.sh under the hood,
 # which only works on uncompressed modules that contain debuginfo
 if grep -q CONFIG_DEBUG_INFO=y include/config/auto.conf &&
    (! grep -q CONFIG_MODULE_COMPRESS=y include/config/auto.conf) &&
    (! grep -q CONFIG_DEBUG_INFO_SPLIT=y include/config/auto.conf); then
-echo '%define with_debuginfo %{?_without_debuginfo: 0} %{?!_without_debuginfo: 1}'
-else
-echo '%define with_debuginfo 0'
+	# If module signing is enabled (which may be required to boot with
+	# lockdown enabled), the find-debuginfo.sh machinery cannot be used
+	# because the signatures will be stripped off the modules. However, due
+	# to an rpm bug in versions prior to 4.20.0
+	#
+	#     https://github.com/rpm-software-management/rpm/issues/3057
+	#     https://github.com/rpm-software-management/rpm/commit/49f906998f3cf1f4152162ca61ac0869251c380f
+	#
+	# We cannot provide our own debuginfo package because it does not listen
+	# to our custom files list, failing the build due to unpackaged files.
+	# Manually generate the debug info package if using rpm 4.20.0. If not
+	# using rpm 4.20.0, avoid generating a -debuginfo package altogether,
+	# as it is not safe.
+	if grep -q CONFIG_MODULE_SIG=y include/config/auto.conf; then
+		rpm_ver_str=$(rpm --version 2>/dev/null)
+		# Split the version on spaces
+		IFS=' '
+		set -- $rpm_ver_str
+		if [ "${1:-}" = RPM -a "${2:-}" = version ]; then
+			IFS=.
+			set -- $3
+			rpm_ver=$(( 1000000 * $1 + 10000 * $2 + 100 * $3 + ${4:-0} ))
+			if [ "$rpm_ver" -ge 4200000 ]; then
+				with_debuginfo_manual='%{?_without_debuginfo:0}%{?!_without_debuginfo:1}'
+			fi
+		fi
+	fi
 fi
+echo "%define with_debuginfo_manual $with_debuginfo_manual"
 
 cat<<EOF
 %define ARCH ${ARCH}