Fix false positive in C++ compiler detection

[blhc/blhc.git] / README

diff --git a/README b/README
index a2adcb8adb761092146c17ee0b2b7350a9a04269..1a93f4c7c779ad52c473be0ba9c7e2ebf2d88b08 100644 (file)
--- a/README
+++ b/README
@@ -4,12 +4,24 @@ README
 blhc (build log hardening check) is a small tool which checks build logs for
 missing hardening flags. It's licensed under the GPL 3 or later.
 
 blhc (build log hardening check) is a small tool which checks build logs for
 missing hardening flags. It's licensed under the GPL 3 or later.
 

+Hardening flags enable additional security features in the compiler to prevent
+e.g. stack overflows, format string vulnerabilities, GOT overwrites, etc.
+
+Because most build systems are quite complicated there are many places where
+compiler flags from the environment might be ignored. The parser verifies that
+all compiler commands use the correct hardening flags and thus all hardening
+features are correctly used.
+

 It's designed to check build logs generated by Debian's dpkg-buildpackage (or
 It's designed to check build logs generated by Debian's dpkg-buildpackage (or

-tools using dpkg-buildpackage like pbuilder or the official buildd build logs)
-to help maintainers detect missing hardening flags in their packages.
+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.

 
 At the moment it works only on Debian and derivatives but it should be easily
 
 At the moment it works only on Debian and derivatives but it should be easily

-extendable for other systems as well.
+extendable to other systems as well. Patches are welcome.
+
+Only gcc is detected as compiler at the moment. If other compilers support
+hardening flags as well, please report them.

 
 For more information about hardening flags have a look at [1].
 
 
 For more information about hardening flags have a look at [1].
 


@@ -22,6 +34,10 @@ DEPENDENCIES
 - Perl
   - Dpkg::Arch
   - Dpkg::Version
 - Perl
   - Dpkg::Arch
   - Dpkg::Version

+  - Term::ANSIColor >= 2.01
+    Bundled with perl. A recent version is only necessary for build logs with
+    ANSI colors which is rare, blhc works fine without if the build log
+    doesn't use colors. Not required for buildd mode.

 
 
 USAGE
 
 
 USAGE


@@ -29,6 +45,12 @@ USAGE
 
     blhc path/to/log/file
 
 
     blhc path/to/log/file
 

+blhc can be run directly from the source tree (`bin/blhc`) or copied anywhere
+on the system. It doesn't have to be explicitly installed. To read the man
+page use `perldoc bin/blhc`.
+
+If there's no output, no flags are missing and the build log is fine.
+

 For more examples see the man page.
 
 
 For more examples see the man page.
 
 


@@ -45,7 +67,7 @@ Consider the following compiler line:
 
 blhc generates the following warnings because all hardening flags are missing:
 
 
 blhc generates the following warnings because all hardening flags are missing:
 

-    CFLAGS missing (-fstack-protector --param=ssp-buffer-size=4 -Wformat -Wformat-security -Werror=format-security): gcc -g -O2 -o test test.c
+    CFLAGS missing (-fstack-protector-strong -Wformat -Werror=format-security): gcc -g -O2 -o test test.c

     CPPFLAGS missing (-D_FORTIFY_SOURCE=2): gcc -g -O2 -o test test.c
     LDFLAGS missing (-Wl,-z,relro): gcc -g -O2 -o test test.c
 
     CPPFLAGS missing (-D_FORTIFY_SOURCE=2): gcc -g -O2 -o test test.c
     LDFLAGS missing (-Wl,-z,relro): gcc -g -O2 -o test test.c
 


@@ -79,6 +101,15 @@ following line (output of dpkg-buildpackage):
 The available hardening flags are adapted to the architecture because some
 architectures don't support certain hardening options.
 
 The available hardening flags are adapted to the architecture because some
 architectures don't support certain hardening options.
 

+Some checks check the build dependencies for certain packages. The following
+lines are used to get the build dependencies. The first two are used in buildd
+build logs (the second was used in older logs), the third by pbuilder logs,
+all are detected:
+
+    Filtered Buildd-Depends: ...
+    Build-Depends: ...
+    Depends: ...
+

 
 LIMITATIONS
 -----------
 
 LIMITATIONS
 -----------


@@ -89,9 +120,13 @@ real compile process (output of dpkg-buildpackage):
     dpkg-buildpackage: ...
 
 If it's not present no compiler commands are detected. In case you don't use
     dpkg-buildpackage: ...
 
 If it's not present no compiler commands are detected. In case you don't use

-dpkp-buildpackage but still want to check a build log adding it as first line
+dpkg-buildpackage but still want to check a build log, adding it as first line

 should work fine.
 
 should work fine.
 

+To prevent false positives when checking debug builds, compiler lines
+containing '-OO' or '-Og' are considered debug builds and are not checked for
+'-O2', even though fortification doesn't work without '-O2'.
+

 The following non-verbose builds can't be detected:
 
     gcc -o test
 The following non-verbose builds can't be detected:
 
     gcc -o test


@@ -139,7 +174,7 @@ LICENSE
 
 blhc is licensed under GPL version 3 or later.
 
 
 blhc is licensed under GPL version 3 or later.
 

-Copyright (C) 2012  Simon Ruderich
+Copyright (C) 2012-2024  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
 
 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


@@ -153,3 +188,5 @@ 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/>.
 
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.

+
+// vim: ft=asciidoc