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From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>,
	Andy Lutomirski <luto@amacapital.net>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Mathias Krause <minipli@googlemail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	x86@kernel.org, Arnd Bergmann <arnd@arndb.de>,
	PaX Team <pageexec@freemail.hu>, Emese Revfy <re.emese@gmail.com>,
	kernel-hardening@lists.openwall.com,
	linux-kernel@vger.kernel.org,
	linux-arch <linux-arch@vger.kernel.org>
Subject: [PATCH v4 0/8] introduce post-init read-only memory
Date: Tue, 19 Jan 2016 10:08:34 -0800	[thread overview]
Message-ID: <1453226922-16831-1-git-send-email-keescook@chromium.org> (raw)

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

             reply	other threads:[~2016-01-19 18:08 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-19 18:08 Kees Cook [this message]
2016-01-19 18:08 ` [PATCH v4 0/8] introduce post-init read-only memory Kees Cook
2016-01-19 18:08 ` [PATCH v4 1/8] asm-generic: consolidate mark_rodata_ro() Kees Cook
2016-01-19 18:08 ` [PATCH v4 2/8] lib: add "on" and "off" to strtobool Kees Cook
2016-01-19 18:08   ` Kees Cook
2016-01-20  2:09   ` Joe Perches
2016-01-22 23:29     ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 3/8] param: convert some "on"/"off" users " Kees Cook
2016-01-27 21:11   ` David Brown
2016-01-27 21:11     ` [kernel-hardening] " David Brown
2016-01-27 21:19     ` Kees Cook
2016-01-28  0:09       ` [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional David Brown
2016-01-28  0:09         ` David Brown
2016-01-28  0:14         ` Kees Cook
2016-01-28  0:14           ` Kees Cook
2016-01-28  8:20           ` Ard Biesheuvel
2016-01-28  8:20             ` Ard Biesheuvel
2016-01-28 11:06         ` Mark Rutland
2016-01-28 11:06           ` Mark Rutland
2016-01-28 14:06           ` Kees Cook
2016-01-28 14:06             ` Kees Cook
2016-01-28 14:59             ` Mark Rutland
2016-01-28 14:59               ` Mark Rutland
2016-01-28 15:17               ` Kees Cook
2016-01-28 15:17                 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 4/8] init: create cmdline param to disable readonly Kees Cook
2016-01-19 18:08   ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 5/8] x86: make CONFIG_DEBUG_RODATA non-optional Kees Cook
2016-01-19 18:08   ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 6/8] introduce post-init read-only memory Kees Cook
2016-01-19 18:08   ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 7/8] lkdtm: verify that __ro_after_init works correctly Kees Cook
2016-01-19 18:08   ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 8/8] x86, vdso: mark vDSO read-only after init Kees Cook
2016-01-19 18:08   ` Kees Cook
2016-01-19 19:09   ` Andy Lutomirski
2016-01-20  2:51   ` H. Peter Anvin
2016-01-20  2:51     ` H. Peter Anvin
2016-01-20  2:56   ` Andy Lutomirski
2016-01-22 17:19 ` [PATCH v4 0/8] introduce post-init read-only memory David Brown
2016-01-22 17:19   ` [kernel-hardening] " David Brown
2016-01-22 19:16   ` Laura Abbott
2016-01-22 19:16     ` Laura Abbott
2016-01-22 19:57     ` Kees Cook
2016-01-23  9:49       ` Geert Uytterhoeven
2016-02-16 21:36 ` [PATCH] ARM: vdso: Mark vDSO code as read-only David Brown
2016-02-16 21:52   ` Kees Cook
2016-02-17  5:20     ` David Brown
2016-02-17 23:00       ` Kees Cook
2016-02-17 23:43         ` David Brown
2016-02-17 23:43           ` David Brown
2016-02-17 23:48           ` Kees Cook
2016-02-18 10:46             ` PaX Team
2016-02-18 10:46               ` PaX Team

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