1. 02 Nov, 2017 1 commit
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      Many source files in the tree are missing licensing information, which
      makes it harder for compliance tools to determine the correct license.
      
      By default all files without license information are under the default
      license of the kernel, which is GPL version 2.
      
      Update the files which contain no license information with the 'GPL-2.0'
      SPDX license identifier.  The SPDX identifier is a legally binding
      shorthand, which can be used instead of the full boiler plate text.
      
      This patch is based on work done by Thomas Gleixner and Kate Stewart and
      Philippe Ombredanne.
      
      How this work was done:
      
      Patches were generated and checked against linux-4.14-rc6 for a subset of
      the use cases:
       - file had no licensing information it it.
       - file was a */uapi/* one with no licensing information in it,
       - file was a */uapi/* one with existing licensing information,
      
      Further patches will be generated in subsequent months to fix up cases
      where non-standard license headers were used, and references to license
      had to be inferred by heuristics based on keywords.
      
      The analysis to determine which SPDX License Identifier to be applied to
      a file was done in a spreadsheet of side by side results from of the
      output of two independent scanners (ScanCode & Windriver) producing SPDX
      tag:value files created by Philippe Ombredanne.  Philippe prepared the
      base worksheet, and did an initial spot review of a few 1000 files.
      
      The 4.13 kernel was the starting point of the analysis with 60,537 files
      assessed.  Kate Stewart did a file by file comparison of the scanner
      results in the spreadsheet to determine which SPDX license identifier(s)
      to be applied to the file. She confirmed any determination that was not
      immediately clear with lawyers working with the Linux Foundation.
      
      Criteria used to select files for SPDX license identifier tagging was:
       - Files considered eligible had to be source code files.
       - Make and config files were included as candidates if they contained >5
         lines of source
       - File already had some variant of a license header in it (even if <5
         lines).
      
      All documentation files were explicitly excluded.
      
      The following heuristics were used to determine which SPDX license
      identifiers to apply.
      
       - when both scanners couldn't find any license traces, file was
         considered to have no license information in it, and the top level
         COPYING file license applied.
      
         For non */uapi/* files that summary was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0                                              11139
      
         and resulted in the first patch in this series.
      
         If that file was a */uapi/* path one, it was "GPL-2.0 WITH
         Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0 WITH Linux-syscall-note                        930
      
         and resulted in the second patch in this series.
      
       - if a file had some form of licensing information in it, and was one
         of the */uapi/* ones, it was denoted with the Linux-syscall-note if
         any GPL family license was found in the file or had no licensing in
         it (per prior point).  Results summary:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|------
         GPL-2.0 WITH Linux-syscall-note                       270
         GPL-2.0+ WITH Linux-syscall-note                      169
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
         LGPL-2.1+ WITH Linux-syscall-note                      15
         GPL-1.0+ WITH Linux-syscall-note                       14
         ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
         LGPL-2.0+ WITH Linux-syscall-note                       4
         LGPL-2.1 WITH Linux-syscall-note                        3
         ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
         ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1
      
         and that resulted in the third patch in this series.
      
       - when the two scanners agreed on the detected license(s), that became
         the concluded license(s).
      
       - when there was disagreement between the two scanners (one detected a
         license but the other didn't, or they both detected different
         licenses) a manual inspection of the file occurred.
      
       - In most cases a manual inspection of the information in the file
         resulted in a clear resolution of the license that should apply (and
         which scanner probably needed to revisit its heuristics).
      
       - When it was not immediately clear, the license identifier was
         confirmed with lawyers working with the Linux Foundation.
      
       - If there was any question as to the appropriate license identifier,
         the file was flagged for further research and to be revisited later
         in time.
      
      In total, over 70 hours of logged manual review was done on the
      spreadsheet to determine the SPDX license identifiers to apply to the
      source files by Kate, Philippe, Thomas and, in some cases, confirmation
      by lawyers working with the Linux Foundation.
      
      Kate also obtained a third independent scan of the 4.13 code base from
      FOSSology, and compared selected files where the other two scanners
      disagreed against that SPDX file, to see if there was new insights.  The
      Windriver scanner is based on an older version of FOSSology in part, so
      they are related.
      
      Thomas did random spot checks in about 500 files from the spreadsheets
      for the uapi headers and agreed with SPDX license identifier in the
      files he inspected. For the non-uapi files Thomas did random spot checks
      in about 15000 files.
      
      In initial set of patches against 4.14-rc6, 3 files were found to have
      copy/paste license identifier errors, and have been fixed to reflect the
      correct identifier.
      
      Additionally Philippe spent 10 hours this week doing a detailed manual
      inspection and review of the 12,461 patched files from the initial patch
      version early this week with:
       - a full scancode scan run, collecting the matched texts, detected
         license ids and scores
       - reviewing anything where there was a license detected (about 500+
         files) to ensure that the applied SPDX license was correct
       - reviewing anything where there was no detection but the patch license
         was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
         SPDX license was correct
      
      This produced a worksheet with 20 files needing minor correction.  This
      worksheet was then exported into 3 different .csv files for the
      different types of files to be modified.
      
      These .csv files were then reviewed by Greg.  Thomas wrote a script to
      parse the csv files and add the proper SPDX tag to the file, in the
      format that the file expected.  This script was further refined by Greg
      based on the output to detect more types of files automatically and to
      distinguish between header and source .c files (which need different
      comment types.)  Finally Greg ran the script using the .csv files to
      generate the patches.
      Reviewed-by: default avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: default avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  2. 07 Aug, 2017 1 commit
    • Ard Biesheuvel's avatar
      gcc-plugins: structleak: add option to init all vars used as byref args · f7dd2507
      Ard Biesheuvel authored
      In the Linux kernel, struct type variables are rarely passed by-value,
      and so functions that initialize such variables typically take an input
      reference to the variable rather than returning a value that can
      subsequently be used in an assignment.
      
      If the initalization function is not part of the same compilation unit,
      the lack of an assignment operation defeats any analysis the compiler
      can perform as to whether the variable may be used before having been
      initialized. This means we may end up passing on such variables
      uninitialized, resulting in potential information leaks.
      
      So extend the existing structleak GCC plugin so it will [optionally]
      apply to all struct type variables that have their address taken at any
      point, rather than only to variables of struct types that have a __user
      annotation.
      Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      f7dd2507
  3. 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
  4. 03 Feb, 2017 2 commits
  5. 18 Jan, 2017 1 commit
    • Kees Cook's avatar
      gcc-plugins: Add structleak for more stack initialization · c61f13ea
      Kees Cook authored
      This plugin detects any structures that contain __user attributes and
      makes sure it is being fully initialized so that a specific class of
      information exposure is eliminated. (This plugin was originally designed
      to block the exposure of siginfo in CVE-2013-2141.)
      
      Ported from grsecurity/PaX. This version adds a verbose option to the
      plugin and the Kconfig.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      c61f13ea
  6. 10 Oct, 2016 1 commit
    • Emese Revfy's avatar
      gcc-plugins: Add latent_entropy plugin · 38addce8
      Emese Revfy authored
      This adds a new gcc plugin named "latent_entropy". It is designed to
      extract as much possible uncertainty from a running system at boot time as
      possible, hoping to capitalize on any possible variation in CPU operation
      (due to runtime data differences, hardware differences, SMP ordering,
      thermal timing variation, cache behavior, etc).
      
      At the very least, this plugin is a much more comprehensive example for
      how to manipulate kernel code using the gcc plugin internals.
      
      The need for very-early boot entropy tends to be very architecture or
      system design specific, so this plugin is more suited for those sorts
      of special cases. The existing kernel RNG already attempts to extract
      entropy from reliable runtime variation, but this plugin takes the idea to
      a logical extreme by permuting a global variable based on any variation
      in code execution (e.g. a different value (and permutation function)
      is used to permute the global based on loop count, case statement,
      if/then/else branching, etc).
      
      To do this, the plugin starts by inserting a local variable in every
      marked function. The plugin then adds logic so that the value of this
      variable is modified by randomly chosen operations (add, xor and rol) and
      random values (gcc generates separate static values for each location at
      compile time and also injects the stack pointer at runtime). The resulting
      value depends on the control flow path (e.g., loops and branches taken).
      
      Before the function returns, the plugin mixes this local variable into
      the latent_entropy global variable. The value of this global variable
      is added to the kernel entropy pool in do_one_initcall() and _do_fork(),
      though it does not credit any bytes of entropy to the pool; the contents
      of the global are just used to mix the pool.
      
      Additionally, the plugin can pre-initialize arrays with build-time
      random contents, so that two different kernel builds running on identical
      hardware will not have the same starting values.
      Signed-off-by: default avatarEmese Revfy <re.emese@gmail.com>
      [kees: expanded commit message and code comments]
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      38addce8
  7. 09 Aug, 2016 3 commits
  8. 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