Annotation of wikisrc/pkgsrc/hardening.mdwn, revision 1.2

1.1       khorben     1: [[!meta title="Hardening pkgsrc"]]
                      2: 
                      3: [pkgsrc](http://www.pkgsrc.org/) supports a number of mechanisms that are meant
                      4: to improve the security of compiled binaries. They can be individually enabled
                      5: in `mk.conf`, and consist of:
                      6: 
                      7: * `PKGSRC_MKPIE`: forces the creation of PIE (Position Independent
                      8:   Executables) when supported on the current platform. This option is necessary
                      9:   to fully leverage ASLR as a mitigation for security vulnerabilities.
                     10: * `PKGSRC_USE_FORTIFY`: allows substitute wrappers to be used for commonly used
                     11:   functions that do not bounds checking regularly - but could in some cases.
                     12: * `PKGSRC_USE_RELRO`: this also makes the exploitation of some security
                     13:   vulnerabilities more difficult in some cases.
                     14: * `PKGSRC_USE_SSP`: enables stack-smashing protection (again, on supported
                     15:   platforms)
                     16: 
1.2     ! khorben    17: # Caveats
        !            18: 
        !            19: ## Problems with `PKGSRC_MKPIE`
        !            20: 
        !            21: ### No support for cwrappers
        !            22: 
        !            23: As of the time of this article `PKGSRC_MKPIE` is not supported by
        !            24: `pkgtools/cwrappers` (`USE_CWRAPPERS` in `mk.conf`).
        !            25: 
        !            26: ### Packages failing to build
        !            27: 
        !            28: A number of packages may fail to build with this option enabled. The failures
        !            29: are often related to the absence of the "-fPIC" compilation flag when building
        !            30: libraries or executables (or ideally "-fPIE" in the latter case). This flag is
        !            31: added to the `CFLAGS` already, but requires the package to actually support it.
        !            32: 
        !            33: #### How to fix
        !            34: 
        !            35: These instructions are meant as a reference only; they likely need to be adapted
        !            36: for many packages individually.
        !            37: 
        !            38: For packages using `Makefiles`:
        !            39: 
        !            40:     MAKE_FLAGS+=       CFLAGS=${CFLAGS:Q}
        !            41:     MAKE_FLAGS+=       LDFLAGS=${LDFLAGS:Q}
        !            42: 
        !            43: For packages using `Imakefiles`:
        !            44: 
        !            45:     MAKE_FLAGS+=       CCOPTIONS=${CFLAGS:Q}
        !            46:     MAKE_FLAGS+=       LOCAL_LDFLAGS=${LDFLAGS:Q}
        !            47: 
        !            48: ### Run-time crashes
        !            49: 
        !            50: Some programs may fail to run, or crash at random times once built as PIE. Two
        !            51: scenarios are essentially possible:
        !            52: 
        !            53: * actual bug in the program crashing, exposed thanks to ASLR/mprotect;
        !            54: * bug in the implementation of ASLR/mprotect in the Operating System.
        !            55: 

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