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authorRichard Fellner <richard.fellner@student.tugraz.at>2017-05-04 14:26:50 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-01-05 15:46:32 +0100
commit13be4483bb487176c48732b887780630a141ae96 (patch)
treef8fbd61a35c304421a50a0c13a198d7877cbf567 /include
parentb5fd58e997cf6294d2c027d585f7dcbd1e096bce (diff)
KAISER: Kernel Address Isolation
This patch introduces our implementation of KAISER (Kernel Address Isolation to have Side-channels Efficiently Removed), a kernel isolation technique to close hardware side channels on kernel address information. More information about the patch can be found on: https://github.com/IAIK/KAISER From: Richard Fellner <richard.fellner@student.tugraz.at> From: Daniel Gruss <daniel.gruss@iaik.tugraz.at> Subject: [RFC, PATCH] x86_64: KAISER - do not map kernel in user mode Date: Thu, 4 May 2017 14:26:50 +0200 Link: http://marc.info/?l=linux-kernel&m=149390087310405&w=2 Kaiser-4.10-SHA1: c4b1831d44c6144d3762ccc72f0c4e71a0c713e5 To: <linux-kernel@vger.kernel.org> To: <kernel-hardening@lists.openwall.com> Cc: <clementine.maurice@iaik.tugraz.at> Cc: <moritz.lipp@iaik.tugraz.at> Cc: Michael Schwarz <michael.schwarz@iaik.tugraz.at> Cc: Richard Fellner <richard.fellner@student.tugraz.at> Cc: Ingo Molnar <mingo@kernel.org> Cc: <kirill.shutemov@linux.intel.com> Cc: <anders.fogh@gdata-adan.de> After several recent works [1,2,3] KASLR on x86_64 was basically considered dead by many researchers. We have been working on an efficient but effective fix for this problem and found that not mapping the kernel space when running in user mode is the solution to this problem [4] (the corresponding paper [5] will be presented at ESSoS17). With this RFC patch we allow anybody to configure their kernel with the flag CONFIG_KAISER to add our defense mechanism. If there are any questions we would love to answer them. We also appreciate any comments! Cheers, Daniel (+ the KAISER team from Graz University of Technology) [1] http://www.ieee-security.org/TC/SP2013/papers/4977a191.pdf [2] https://www.blackhat.com/docs/us-16/materials/us-16-Fogh-Using-Undocumented-CPU-Behaviour-To-See-Into-Kernel-Mode-And-Break-KASLR-In-The-Process.pdf [3] https://www.blackhat.com/docs/us-16/materials/us-16-Jang-Breaking-Kernel-Address-Space-Layout-Randomization-KASLR-With-Intel-TSX.pdf [4] https://github.com/IAIK/KAISER [5] https://gruss.cc/files/kaiser.pdf [patch based also on https://raw.githubusercontent.com/IAIK/KAISER/master/KAISER/0001-KAISER-Kernel-Address-Isolation.patch] Signed-off-by: Richard Fellner <richard.fellner@student.tugraz.at> Signed-off-by: Moritz Lipp <moritz.lipp@iaik.tugraz.at> Signed-off-by: Daniel Gruss <daniel.gruss@iaik.tugraz.at> Signed-off-by: Michael Schwarz <michael.schwarz@iaik.tugraz.at> Acked-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/vmlinux.lds.h11
-rw-r--r--include/linux/percpu-defs.h30
2 files changed, 40 insertions, 1 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index dc81e5287ebf..d6ab14414776 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -778,7 +778,16 @@
*/
#define PERCPU_INPUT(cacheline) \
VMLINUX_SYMBOL(__per_cpu_start) = .; \
- *(.data..percpu..first) \
+ \
+ VMLINUX_SYMBOL(__per_cpu_user_mapped_start) = .; \
+ *(.data..percpu..first) \
+ . = ALIGN(cacheline); \
+ *(.data..percpu..user_mapped) \
+ *(.data..percpu..user_mapped..shared_aligned) \
+ . = ALIGN(PAGE_SIZE); \
+ *(.data..percpu..user_mapped..page_aligned) \
+ VMLINUX_SYMBOL(__per_cpu_user_mapped_end) = .; \
+ \
. = ALIGN(PAGE_SIZE); \
*(.data..percpu..page_aligned) \
. = ALIGN(cacheline); \
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index 8f16299ca068..8ea945f63a05 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -35,6 +35,12 @@
#endif
+#ifdef CONFIG_KAISER
+#define USER_MAPPED_SECTION "..user_mapped"
+#else
+#define USER_MAPPED_SECTION ""
+#endif
+
/*
* Base implementations of per-CPU variable declarations and definitions, where
* the section in which the variable is to be placed is provided by the
@@ -115,6 +121,12 @@
#define DEFINE_PER_CPU(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "")
+#define DECLARE_PER_CPU_USER_MAPPED(type, name) \
+ DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION)
+
+#define DEFINE_PER_CPU_USER_MAPPED(type, name) \
+ DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION)
+
/*
* Declaration/definition used for per-CPU variables that must come first in
* the set of variables.
@@ -144,6 +156,14 @@
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
____cacheline_aligned_in_smp
+#define DECLARE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(type, name) \
+ DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION PER_CPU_SHARED_ALIGNED_SECTION) \
+ ____cacheline_aligned_in_smp
+
+#define DEFINE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(type, name) \
+ DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION PER_CPU_SHARED_ALIGNED_SECTION) \
+ ____cacheline_aligned_in_smp
+
#define DECLARE_PER_CPU_ALIGNED(type, name) \
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
____cacheline_aligned
@@ -162,6 +182,16 @@
#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \
__aligned(PAGE_SIZE)
+/*
+ * Declaration/definition used for per-CPU variables that must be page aligned and need to be mapped in user mode.
+ */
+#define DECLARE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(type, name) \
+ DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION"..page_aligned") \
+ __aligned(PAGE_SIZE)
+
+#define DEFINE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(type, name) \
+ DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION"..page_aligned") \
+ __aligned(PAGE_SIZE)
/*
* Declaration/definition used for per-CPU variables that must be read mostly.