1. 20 12月, 2013 2 次提交
    • K
      stackprotector: Introduce CONFIG_CC_STACKPROTECTOR_STRONG · 8779657d
      Kees Cook 提交于
      This changes the stack protector config option into a choice of
      "None", "Regular", and "Strong":
      
         CONFIG_CC_STACKPROTECTOR_NONE
         CONFIG_CC_STACKPROTECTOR_REGULAR
         CONFIG_CC_STACKPROTECTOR_STRONG
      
      "Regular" means the old CONFIG_CC_STACKPROTECTOR=y option.
      
      "Strong" is a new mode introduced by this patch. With "Strong" the
      kernel is built with -fstack-protector-strong (available in
      gcc 4.9 and later). This option increases the coverage of the stack
      protector without the heavy performance hit of -fstack-protector-all.
      
      For reference, the stack protector options available in gcc are:
      
      -fstack-protector-all:
        Adds the stack-canary saving prefix and stack-canary checking
        suffix to _all_ function entry and exit. Results in substantial
        use of stack space for saving the canary for deep stack users
        (e.g. historically xfs), and measurable (though shockingly still
        low) performance hit due to all the saving/checking. Really not
        suitable for sane systems, and was entirely removed as an option
        from the kernel many years ago.
      
      -fstack-protector:
        Adds the canary save/check to functions that define an 8
        (--param=ssp-buffer-size=N, N=8 by default) or more byte local
        char array. Traditionally, stack overflows happened with
        string-based manipulations, so this was a way to find those
        functions. Very few total functions actually get the canary; no
        measurable performance or size overhead.
      
      -fstack-protector-strong
        Adds the canary for a wider set of functions, since it's not
        just those with strings that have ultimately been vulnerable to
        stack-busting. With this superset, more functions end up with a
        canary, but it still remains small compared to all functions
        with only a small change in performance. Based on the original
        design document, a function gets the canary when it contains any
        of:
      
          - local variable's address used as part of the right hand side
            of an assignment or function argument
          - local variable is an array (or union containing an array),
            regardless of array type or length
          - uses register local variables
      
        https://docs.google.com/a/google.com/document/d/1xXBH6rRZue4f296vGt9YQcuLVQHeE516stHwt8M9xyU
      
      Find below a comparison of "size" and "objdump" output when built with
      gcc-4.9 in three configurations:
      
        - defconfig
      	11430641 kernel text size
      	36110 function bodies
      
        - defconfig + CONFIG_CC_STACKPROTECTOR_REGULAR
      	11468490 kernel text size (+0.33%)
      	1015 of 36110 functions are stack-protected (2.81%)
      
        - defconfig + CONFIG_CC_STACKPROTECTOR_STRONG via this patch
      	11692790 kernel text size (+2.24%)
      	7401 of 36110 functions are stack-protected (20.5%)
      
      With -strong, ARM's compressed boot code now triggers stack
      protection, so a static guard was added. Since this is only used
      during decompression and was never used before, the exposure
      here is very small. Once it switches to the full kernel, the
      stack guard is back to normal.
      
      Chrome OS has been using -fstack-protector-strong for its kernel
      builds for the last 8 months with no problems.
      Signed-off-by: NKees Cook <keescook@chromium.org>
      Cc: Arjan van de Ven <arjan@linux.intel.com>
      Cc: Michal Marek <mmarek@suse.cz>
      Cc: Russell King <linux@arm.linux.org.uk>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Paul Mundt <lethal@linux-sh.org>
      Cc: James Hogan <james.hogan@imgtec.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: Shawn Guo <shawn.guo@linaro.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: linux-arm-kernel@lists.infradead.org
      Cc: linux-mips@linux-mips.org
      Cc: linux-arch@vger.kernel.org
      Link: http://lkml.kernel.org/r/1387481759-14535-3-git-send-email-keescook@chromium.org
      [ Improved the changelog and descriptions some more. ]
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      8779657d
    • K
      stackprotector: Unify the HAVE_CC_STACKPROTECTOR logic between architectures · 19952a92
      Kees Cook 提交于
      Instead of duplicating the CC_STACKPROTECTOR Kconfig and
      Makefile logic in each architecture, switch to using
      HAVE_CC_STACKPROTECTOR and keep everything in one place. This
      retains the x86-specific bug verification scripts.
      Signed-off-by: NKees Cook <keescook@chromium.org>
      Cc: Arjan van de Ven <arjan@linux.intel.com>
      Cc: Michal Marek <mmarek@suse.cz>
      Cc: Russell King <linux@arm.linux.org.uk>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Paul Mundt <lethal@linux-sh.org>
      Cc: James Hogan <james.hogan@imgtec.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: Shawn Guo <shawn.guo@linaro.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-arm-kernel@lists.infradead.org
      Cc: linux-mips@linux-mips.org
      Cc: linux-arch@vger.kernel.org
      Link: http://lkml.kernel.org/r/1387481759-14535-2-git-send-email-keescook@chromium.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      19952a92
  2. 14 12月, 2013 1 次提交
    • R
      ARM: fix asm/memory.h build error · b713aa0b
      Russell King 提交于
      Jason Gunthorpe reports a build failure when ARM_PATCH_PHYS_VIRT is
      not defined:
      
      In file included from arch/arm/include/asm/page.h:163:0,
                       from include/linux/mm_types.h:16,
                       from include/linux/sched.h:24,
                       from arch/arm/kernel/asm-offsets.c:13:
      arch/arm/include/asm/memory.h: In function '__virt_to_phys':
      arch/arm/include/asm/memory.h:244:40: error: 'PHYS_OFFSET' undeclared (first use in this function)
      arch/arm/include/asm/memory.h:244:40: note: each undeclared identifier is reported only once for each function it appears in
      arch/arm/include/asm/memory.h: In function '__phys_to_virt':
      arch/arm/include/asm/memory.h:249:13: error: 'PHYS_OFFSET' undeclared (first use in this function)
      
      Fixes: ca5a45c0 ("ARM: mm: use phys_addr_t appropriately in p2v and v2p conversions")
      Tested-By: NJason Gunthorpe <jgunthorpe@obsidianresearch.com>
      Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      b713aa0b
  3. 13 12月, 2013 13 次提交
  4. 12 12月, 2013 5 次提交
  5. 11 12月, 2013 4 次提交
  6. 10 12月, 2013 15 次提交