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blhc - build log hardening check, checks build logs for missing hardening flags

BLHC(1) User Contributed Perl Documentation BLHC(1)

NAME

blhc - build log hardening check, checks build logs for missing hardening flags

SYNOPSIS

blhc [options] <dpkg-buildpackage build log file>..

DESCRIPTION

blhc is a small tool which checks build logs for missing hardening flags. It's licensed under the GPL 3 or later.
It's designed to check build logs generated by Debian's dpkg-buildpackage (or tools using dpkg-buildpackage like pbuilder or sbuild (which is used for the official buildd build logs)) to help maintainers detect missing hardening flags in their packages.
Only gcc is detected as compiler at the moment. If other compilers support hardening flags as well, please report them.
If there's no output, no flags are missing and the build log is fine.
See README for details about performed checks, auto-detection and limitations.

OPTIONS

--all
Force check for all +all (+pie, +bindnow) hardening flags. By default it's auto detected.
--arch architecture
Set the specific architecture (e.g. amd64, armel, etc.), automatically disables hardening flags not available on this architecture. Is detected automatically if dpkg-buildpackage is used.
--bindnow
Force check for all +bindnow hardening flags. By default it's auto detected.
--buildd
Special mode for buildds when automatically parsing log files. The following changes are in effect:
Print tags instead of normal warnings, see "BUILDD TAGS" for a list of possible tags.
Don't check hardening flags in old log files (if dpkg-dev << 1.16.1 is detected).
Don't require Term::ANSIColor.
Return exit code 0, unless there was a error (-I, -W messages don't count as error).
--debian
Apply Debian-specific settings. At the moment this only disables checking for PIE which is automatically applied by Debian's GCC and no longer requires a compiler command line argument.
--color
Use colored (ANSI) output for warning messages.
--ignore-arch arch
Ignore build logs from architectures matching arch. arch is a string.
 
Used to prevent false positives. This option can be specified multiple times.
--ignore-arch-flag arch:flag
Like --ignore-flag, but only ignore flag on arch.
--ignore-arch-line arch:line
Like --ignore-line, but only ignore line on arch.
--ignore-flag flag
Don't print an error when the specific flag is missing in a compiler line. flag is a string.
 
Used to prevent false positives. This option can be specified multiple times.
--ignore-line regex
Ignore lines matching the given Perl regex. regex is automatically anchored at the beginning and end of the line to prevent false negatives.
 
NOTE: Not the input lines are checked, but the lines which are displayed in warnings (which have line continuation resolved).
 
Used to prevent false positives. This option can be specified multiple times.
--pie
Force check for all +pie hardening flags. By default it's auto detected.
-h -? --help
Print available options.
--version
Print version number and license.
Auto detection for --pie and --bindnow only works if at least one command uses the required hardening flag (e.g. -fPIE). Then it's required for all other commands as well.

EXAMPLES

Normal usage, parse a single log file.
    blhc path/to/log/file
If there's no output, no flags are missing and the build log is fine.
Parse multiple log files. The exit code is ORed over all files.
    blhc path/to/directory/with/log/files/*
Don't treat missing "-g" as error:
    blhc --ignore-flag -g path/to/log/file
Don't treat missing "-pie" on kfreebsd-amd64 as error:
    blhc --ignore-arch-flag kfreebsd-amd64:-pie path/to/log/file
Ignore lines consisting exactly of "./script gcc file" which would cause a false positive.
    blhc --ignore-line '\./script gcc file' path/to/log/file
Ignore lines matching "./script gcc file" somewhere in the line.
    blhc --ignore-line '.*\./script gcc file.*' path/to/log/file
Use blhc with pbuilder.
    pbuilder path/to/package.dsc | tee path/log/file
    blhc path/to/file || echo flags missing

BUILDD TAGS

The following tags are used in --buildd mode. In braces the additional data which is displayed.
I-hardening-wrapper-used
The package uses hardening-wrapper which intercepts calls to gcc and adds hardening flags. The build log doesn't contain any hardening flags and thus can't be checked by blhc.
W-compiler-flags-hidden (summary of hidden lines)
Build log contains lines which hide the real compiler flags. For example:
 
    CC test-a.c
    CC test-b.c
    CC test-c.c
    LD test
    
 
Most of the time either "export V=1" or "export verbose=1" in debian/rules fixes builds with hidden compiler flags. Sometimes ".SILENT" in a Makefile must be removed. And as last resort the Makefile must be patched to remove the "@"s hiding the real compiler commands.
W-dpkg-buildflags-missing (summary of missing flags)
CPPFLAGS, CFLAGS, CXXFLAGS, LDFLAGS missing.
I-invalid-cmake-used (version)
By default CMake ignores CPPFLAGS thus missing those hardening flags. Debian patched CMake in versions 2.8.7-1 and 2.8.7-2 to respect CPPFLAGS, but this patch was rejected by upstream and later reverted in Debian. Thus those two versions show correct usage of CPPFLAGS even if the package doesn't correctly handle them (for example by passing them to CFLAGS). To prevent false negatives just blacklist those two versions.
I-no-compiler-commands
No compiler commands were detected. Either the log contains none or they were not correctly detected by blhc (please report the bug in this case).

EXIT STATUS

The exit status is a "bit mask", each listed status is ORed when the error condition occurs to get the result.
0
Success.
1
No compiler commands were found.
2
Invalid arguments/options given to blhc.
4
Non verbose build.
8
Missing hardening flags.
16
Hardening wrapper detected, no tests performed.
32
Invalid CMake version used. See I-invalid-cmake-used under "BUILDD TAGS" for a detailed explanation.

AUTHOR

Simon Ruderich, <simon@ruderich.org>
Thanks to to Bernhard R. Link <brlink@debian.org> and Jaria Alto <jari.aalto@cante.net> for their valuable input and suggestions. Copyright (C) 2012-2017 by Simon Ruderich
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.

SEE ALSO

hardening-check(1), dpkg-buildflags(1)
2017-09-05 perl v5.26.0