1. 22 Jun, 2017 1 commit
    • Kees Cook's avatar
      gcc-plugins: Add the randstruct plugin · 313dd1b6
      Kees Cook authored
      This randstruct plugin is modified from Brad Spengler/PaX Team's code
      in the last public patch of grsecurity/PaX based on my understanding
      of the code. Changes or omissions from the original code are mine and
      don't reflect the original grsecurity/PaX code.
      
      The randstruct GCC plugin randomizes the layout of selected structures
      at compile time, as a probabilistic defense against attacks that need to
      know the layout of structures within the kernel. This is most useful for
      "in-house" kernel builds where neither the randomization seed nor other
      build artifacts are made available to an attacker. While less useful for
      distribution kernels (where the randomization seed must be exposed for
      third party kernel module builds), it still has some value there since now
      all kernel builds would need to be tracked by an attacker.
      
      In more performance sensitive scenarios, GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
      can be selected to make a best effort to restrict randomization to
      cacheline-sized groups of elements, and will not randomize bitfields. This
      comes at the cost of reduced randomization.
      
      Two annotations are defined,__randomize_layout and __no_randomize_layout,
      which respectively tell the plugin to either randomize or not to
      randomize instances of the struct in question. Follow-on patches enable
      the auto-detection logic for selecting structures for randomization
      that contain only function pointers. It is disabled here to assist with
      bisection.
      
      Since any randomized structs must be initialized using designated
      initializers, __randomize_layout includes the __designated_init annotation
      even when the plugin is disabled so that all builds will require
      the needed initialization. (With the plugin enabled, annotations for
      automatically chosen structures are marked as well.)
      
      The main differences between this implemenation and grsecurity are:
      - disable automatic struct selection (to be enabled in follow-up patch)
      - add designated_init attribute at runtime and for manual marking
      - clarify debugging output to differentiate bad cast warnings
      - add whitelisting infrastructure
      - support gcc 7's DECL_ALIGN and DECL_MODE changes (Laura Abbott)
      - raise minimum required GCC version to 4.7
      
      Earlier versions of this patch series were ported by Michael Leibowitz.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      313dd1b6
  2. 09 Aug, 2016 2 commits
  3. 07 Jun, 2016 3 commits
    • Emese Revfy's avatar
      Add sancov plugin · 543c37cb
      Emese Revfy authored
      The sancov gcc plugin inserts a __sanitizer_cov_trace_pc() call
      at the start of basic blocks.
      
      This plugin is a helper plugin for the kcov feature. It supports
      all gcc versions with plugin support (from gcc-4.5 on).
      It is based on the gcc commit "Add fuzzing coverage support" by Dmitry Vyukov
      (https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296).
      Signed-off-by: default avatarEmese Revfy <re.emese@gmail.com>
      Acked-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
      543c37cb
    • Emese Revfy's avatar
      Add Cyclomatic complexity GCC plugin · 0dae776c
      Emese Revfy authored
      Add a very simple plugin to demonstrate the GCC plugin infrastructure. This GCC
      plugin computes the cyclomatic complexity of each function.
      
      The complexity M of a function's control flow graph is defined as:
      M = E - N + 2P
      where
      E = the number of edges
      N = the number of nodes
      P = the number of connected components (exit nodes).
      Signed-off-by: default avatarEmese Revfy <re.emese@gmail.com>
      Acked-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
      0dae776c
    • Emese Revfy's avatar
      GCC plugin infrastructure · 6b90bd4b
      Emese Revfy authored
      This patch allows to build the whole kernel with GCC plugins. It was ported from
      grsecurity/PaX. The infrastructure supports building out-of-tree modules and
      building in a separate directory. Cross-compilation is supported too.
      Currently the x86, arm, arm64 and uml architectures enable plugins.
      
      The directory of the gcc plugins is scripts/gcc-plugins. You can use a file or a directory
      there. The plugins compile with these options:
       * -fno-rtti: gcc is compiled with this option so the plugins must use it too
       * -fno-exceptions: this is inherited from gcc too
       * -fasynchronous-unwind-tables: this is inherited from gcc too
       * -ggdb: it is useful for debugging a plugin (better backtrace on internal
          errors)
       * -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
       * -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
          variable, plugin-version.h)
      
      The infrastructure introduces a new Makefile target called gcc-plugins. It
      supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
      chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
      This script also checks the availability of the included headers in
      scripts/gcc-plugins/gcc-common.h.
      
      The gcc-common.h header contains frequently included headers for GCC plugins
      and it has a compatibility layer for the supported gcc versions.
      
      The gcc-generate-*-pass.h headers automatically generate the registration
      structures for GIMPLE, SIMPLE_IPA, IPA and RTL passes.
      
      Note that 'make clean' keeps the *.so files (only the distclean or mrproper
      targets clean all) because they are needed for out-of-tree modules.
      
      Based on work created by the PaX Team.
      Signed-off-by: default avatarEmese Revfy <re.emese@gmail.com>
      Acked-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
      6b90bd4b