dpkg-genbuildinfo: Add support for new Build-Kernel-Version field

Packages intended to be built in a generic way must never rely on the
currently running kernel on the build system (an exception could be an
optimization rebuild using the current system as the reference baseline).

But to be able to detect when a package might not be reproducible due to
varying kernel information it is still useful to be able to record this
information. Although that information can be very sensitive.

When the builder has explicitly enabled the Build-Kernel-Version field
with the new dpkg-genbuildinfo --always-include-kernel option, it will
get included in the generated .buildinfo file.

Closes: #873937

1 files changed, 9 insertions, 0 deletions

diff --git a/scripts/dpkg-genbuildinfo.pl b/scripts/dpkg-genbuildinfo.pl
index 3682f2f02..45c45089d 100755
--- a/scripts/dpkg-genbuildinfo.pl
+++ b/scripts/dpkg-genbuildinfo.pl
@@ -61,6 +61,7 @@ my $outputfile;
 my $stdout = 0;
 my $admindir = $Dpkg::ADMINDIR;
 my %use_feature = (
+    kernel => 0,
     path => 0,
 );
 my @build_profiles = get_build_profiles();
@@ -294,6 +295,7 @@ sub usage {
   -F<changelog-format>     force changelog format.
   -O[<buildinfo-file>]     write to stdout (or <buildinfo-file>).
   -u<upload-files-dir>     directory with files (default is '..').
+  --always-include-kernel  always include Build-Kernel-Version.
   --always-include-path    always include Build-Path.
   --admindir=<directory>   change the administrative directory.
   -?, --help               show this help message.
@@ -325,6 +327,8 @@ while (@ARGV) {
     } elsif (m/^--buildinfo-id=.*$/) {
         # Deprecated option
         warning('--buildinfo-id is deprecated, it is without effect');
+    } elsif (m/^--always-include-kernel$/) {
+        $use_feature{kernel} = 1;
     } elsif (m/^--always-include-path$/) {
         $use_feature{path} = 1;
     } elsif (m/^--admindir=(.*)$/) {
@@ -415,6 +419,11 @@ $fields->{'Build-Origin'} = get_current_vendor();
 $fields->{'Build-Architecture'} = get_build_arch();
 $fields->{'Build-Date'} = get_build_date();
 
+if ($use_feature{kernel}) {
+    my (undef, undef, $kern_rel, $kern_ver, undef) = POSIX::uname();
+    $fields->{'Build-Kernel-Version'} = "$kern_rel $kern_ver";
+}
+
 my $cwd = cwd();
 if ($use_feature{path}) {
     $fields->{'Build-Path'} = $cwd;