[PATCH v4 0/8] introduce post-init read-only memory

From	Kees Cook <keescook@chromium.org>
Newsgroups	linux.kernel
Subject	[PATCH v4 0/8] introduce post-init read-only memory
Date	2016-01-19 19:20 +0100
Message-ID	<qSIT8-33H-5@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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One of the easiest ways to protect the kernel from attack is to reduce
the internal attack surface exposed when a "write" flaw is available. By
making as much of the kernel read-only as possible, we reduce the
attack surface.

Many things are written to only during __init, and never changed
again. These cannot be made "const" since the compiler will do the wrong
thing (we do actually need to write to them). Instead, move these items
into a memory region that will be made read-only during mark_rodata_ro()
which happens after all kernel __init code has finished.

This introduces __ro_after_init as a way to mark such memory, and uses
it on the x86 vDSO to kill an extant kernel exploitation method. Also
adds a new kernel parameter to help debug future use and adds an lkdtm
test to check the results.

-Kees

v4:
- rebased
v3:
- conslidated mark_rodata_ro()
- make CONFIG_DEBUG_RODATA always enabled on x86, mingo
- enhanced strtobool and potential callers to use "on"/"off"
- use strtobool for rodata= param, gregkh
v2:
- renamed __read_only to __ro_after_init

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[PATCH v4 0/8] introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2016-01-19 19:20 +0100
  [PATCH v4 7/8] lkdtm: verify that __ro_after_init works correctly Kees Cook <keescook@chromium.org> - 2016-01-19 19:20 +0100
  Re: [kernel-hardening] [PATCH v4 0/8] introduce post-init read-only  memory David Brown <david.brown@linaro.org> - 2016-01-22 18:30 +0100
    Re: [kernel-hardening] [PATCH v4 0/8] introduce post-init read-only  memory Laura Abbott <laura@labbott.name> - 2016-01-22 20:20 +0100
      Re: [kernel-hardening] [PATCH v4 0/8] introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2016-01-22 21:00 +0100
        Re: [kernel-hardening] [PATCH v4 0/8] introduce post-init read-only memory Geert Uytterhoeven <geert@linux-m68k.org> - 2016-01-23 10:50 +0100

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