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  1. 03 8月, 2018 1 次提交
    • S
      x86/speculation: Support Enhanced IBRS on future CPUs · 706d5168
      由 Sai Praneeth 提交于 
      Future Intel processors will support "Enhanced IBRS" which is an "always
on" mode i.e. IBRS bit in SPEC_CTRL MSR is enabled once and never
disabled.

From the specification [1]:

 "With enhanced IBRS, the predicted targets of indirect branches
  executed cannot be controlled by software that was executed in a less
  privileged predictor mode or on another logical processor. As a
  result, software operating on a processor with enhanced IBRS need not
  use WRMSR to set IA32_SPEC_CTRL.IBRS after every transition to a more
  privileged predictor mode. Software can isolate predictor modes
  effectively simply by setting the bit once. Software need not disable
  enhanced IBRS prior to entering a sleep state such as MWAIT or HLT."

If Enhanced IBRS is supported by the processor then use it as the
preferred spectre v2 mitigation mechanism instead of Retpoline. Intel's
Retpoline white paper [2] states:

 "Retpoline is known to be an effective branch target injection (Spectre
  variant 2) mitigation on Intel processors belonging to family 6
  (enumerated by the CPUID instruction) that do not have support for
  enhanced IBRS. On processors that support enhanced IBRS, it should be
  used for mitigation instead of retpoline."

The reason why Enhanced IBRS is the recommended mitigation on processors
which support it is that these processors also support CET which
provides a defense against ROP attacks. Retpoline is very similar to ROP
techniques and might trigger false positives in the CET defense.

If Enhanced IBRS is selected as the mitigation technique for spectre v2,
the IBRS bit in SPEC_CTRL MSR is set once at boot time and never
cleared. Kernel also has to make sure that IBRS bit remains set after
VMEXIT because the guest might have cleared the bit. This is already
covered by the existing x86_spec_ctrl_set_guest() and
x86_spec_ctrl_restore_host() speculation control functions.

Enhanced IBRS still requires IBPB for full mitigation.

[1] Speculative-Execution-Side-Channel-Mitigations.pdf
[2] Retpoline-A-Branch-Target-Injection-Mitigation.pdf
Both documents are available at:
https://bugzilla.kernel.org/show_bug.cgi?id=199511Originally-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NSai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Tim C Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Link: https://lkml.kernel.org/r/1533148945-24095-1-git-send-email-sai.praneeth.prakhya@intel.com
      706d5168
  3. 31 7月, 2018 1 次提交
  5. 20 7月, 2018 1 次提交
    • J
      x86/entry/32: Enter the kernel via trampoline stack · 45d7b255
      由 Joerg Roedel 提交于 
      Use the entry-stack as a trampoline to enter the kernel. The entry-stack is
already in the cpu_entry_area and will be mapped to userspace when PTI is
enabled.
Signed-off-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NPavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-8-git-send-email-joro@8bytes.org
      45d7b255
  7. 08 7月, 2018 1 次提交
  9. 03 7月, 2018 2 次提交
  11. 23 6月, 2018 2 次提交
  13. 22 6月, 2018 3 次提交
    • Z
      x86/microcode/intel: Fix memleak in save_microcode_patch() · 0218c766
      由 Zhenzhong Duan 提交于 
      Free useless ucode_patch entry when it's replaced.

[ bp: Drop the memfree_patch() two-liner. ]
Signed-off-by: NZhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Srinivas REDDY Eeda <srinivas.eeda@oracle.com>
Link: http://lkml.kernel.org/r/888102f0-fd22-459d-b090-a1bd8a00cb2b@default
      0218c766
    • T
      x86/mce: Fix incorrect "Machine check from unknown source" message · 40c36e27
      由 Tony Luck 提交于 
      Some injection testing resulted in the following console log:

  mce: [Hardware Error]: CPU 22: Machine Check Exception: f Bank 1: bd80000000100134
  mce: [Hardware Error]: RIP 10:<ffffffffc05292dd> {pmem_do_bvec+0x11d/0x330 [nd_pmem]}
  mce: [Hardware Error]: TSC c51a63035d52 ADDR 3234bc4000 MISC 88
  mce: [Hardware Error]: PROCESSOR 0:50654 TIME 1526502199 SOCKET 0 APIC 38 microcode 2000043
  mce: [Hardware Error]: Run the above through 'mcelog --ascii'
  Kernel panic - not syncing: Machine check from unknown source

This confused everybody because the first line quite clearly shows
that we found a logged error in "Bank 1", while the last line says
"unknown source".

The problem is that the Linux code doesn't do the right thing
for a local machine check that results in a fatal error.

It turns out that we know very early in the handler whether the
machine check is fatal. The call to mce_no_way_out() has checked
all the banks for the CPU that took the local machine check. If
it says we must crash, we can do so right away with the right
messages.

We do scan all the banks again. This means that we might initially
not see a problem, but during the second scan find something fatal.
If this happens we print a slightly different message (so I can
see if it actually every happens).

[ bp: Remove unneeded severity assignment. ]
Signed-off-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: stable@vger.kernel.org # 4.2
Link: http://lkml.kernel.org/r/52e049a497e86fd0b71c529651def8871c804df0.1527283897.git.tony.luck@intel.com
      40c36e27
    • B
      x86/mce: Do not overwrite MCi_STATUS in mce_no_way_out() · 1f74c8a6
      由 Borislav Petkov 提交于 
      mce_no_way_out() does a quick check during #MC to see whether some of
the MCEs logged would require the kernel to panic immediately. And it
passes a struct mce where MCi_STATUS gets written.

However, after having saved a valid status value, the next iteration
of the loop which goes over the MCA banks on the CPU, overwrites the
valid status value because we're using struct mce as storage instead of
a temporary variable.

Which leads to MCE records with an empty status value:

  mce: [Hardware Error]: CPU 0: Machine Check Exception: 6 Bank 0: 0000000000000000
  mce: [Hardware Error]: RIP 10:<ffffffffbd42fbd7> {trigger_mce+0x7/0x10}

In order to prevent the loss of the status register value, return
immediately when severity is a panic one so that we can panic
immediately with the first fatal MCE logged. This is also the intention
of this function and not to noodle over the banks while a fatal MCE is
already logged.

Tony: read the rest of the MCA bank to populate the struct mce fully.
Suggested-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20180622095428.626-8-bp@alien8.de
      1f74c8a6
  15. 21 6月, 2018 1 次提交
  17. 14 6月, 2018 1 次提交
    • L
      Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables · 050e9baa
      由 Linus Torvalds 提交于 
      The changes to automatically test for working stack protector compiler
support in the Kconfig files removed the special STACKPROTECTOR_AUTO
option that picked the strongest stack protector that the compiler
supported.

That was all a nice cleanup - it makes no sense to have the AUTO case
now that the Kconfig phase can just determine the compiler support
directly.

HOWEVER.

It also meant that doing "make oldconfig" would now _disable_ the strong
stackprotector if you had AUTO enabled, because in a legacy config file,
the sane stack protector configuration would look like

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_NONE is not set
  # CONFIG_CC_STACKPROTECTOR_REGULAR is not set
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_STACKPROTECTOR_AUTO=y

and when you ran this through "make oldconfig" with the Kbuild changes,
it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had
been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just
CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version
used to be disabled (because it was really enabled by AUTO), and would
disable it in the new config, resulting in:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

That's dangerously subtle - people could suddenly find themselves with
the weaker stack protector setup without even realizing.

The solution here is to just rename not just the old RECULAR stack
protector option, but also the strong one.  This does that by just
removing the CC_ prefix entirely for the user choices, because it really
is not about the compiler support (the compiler support now instead
automatially impacts _visibility_ of the options to users).

This results in "make oldconfig" actually asking the user for their
choice, so that we don't have any silent subtle security model changes.
The end result would generally look like this:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_STACKPROTECTOR=y
  CONFIG_STACKPROTECTOR_STRONG=y
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

where the "CC_" versions really are about internal compiler
infrastructure, not the user selections.
Acked-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      050e9baa
  19. 13 6月, 2018 1 次提交
    • K
      treewide: kzalloc() -> kcalloc() · 6396bb22
      由 Kees Cook 提交于 
      The kzalloc() function has a 2-factor argument form, kcalloc(). This
patch replaces cases of:

        kzalloc(a * b, gfp)

with:
        kcalloc(a * b, gfp)

as well as handling cases of:

        kzalloc(a * b * c, gfp)

with:

        kzalloc(array3_size(a, b, c), gfp)

as it's slightly less ugly than:

        kzalloc_array(array_size(a, b), c, gfp)

This does, however, attempt to ignore constant size factors like:

        kzalloc(4 * 1024, gfp)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@

(
  kzalloc(
-	(sizeof(TYPE)) * E
+	sizeof(TYPE) * E
  , ...)
|
  kzalloc(
-	(sizeof(THING)) * E
+	sizeof(THING) * E
  , ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@

(
  kzalloc(
-	sizeof(u8) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(__u8) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(char) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(unsigned char) * (COUNT)
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(u8) * COUNT
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(__u8) * COUNT
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(char) * COUNT
+	COUNT
  , ...)
|
  kzalloc(
-	sizeof(unsigned char) * COUNT
+	COUNT
  , ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * (COUNT_ID)
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * COUNT_ID
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * (COUNT_CONST)
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * COUNT_CONST
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * (COUNT_ID)
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * COUNT_ID
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * (COUNT_CONST)
+	COUNT_CONST, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * COUNT_CONST
+	COUNT_CONST, sizeof(THING)
  , ...)
)

// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@

- kzalloc
+ kcalloc
  (
-	SIZE * COUNT
+	COUNT, SIZE
  , ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
  kzalloc(
-	sizeof(TYPE) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc(
-	sizeof(TYPE) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc(
-	sizeof(TYPE) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc(
-	sizeof(TYPE) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kzalloc(
-	sizeof(THING) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc(
-	sizeof(THING) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc(
-	sizeof(THING) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kzalloc(
-	sizeof(THING) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
  kzalloc(
-	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kzalloc(
-	sizeof(THING1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kzalloc(
-	sizeof(THING1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
|
  kzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@

(
  kzalloc(
-	(COUNT) * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	COUNT * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	COUNT * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	(COUNT) * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	COUNT * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	(COUNT) * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	(COUNT) * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kzalloc(
-	COUNT * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
)

// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
  kzalloc(C1 * C2 * C3, ...)
|
  kzalloc(
-	(E1) * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc(
-	(E1) * (E2) * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc(
-	(E1) * (E2) * (E3)
+	array3_size(E1, E2, E3)
  , ...)
|
  kzalloc(
-	E1 * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
)

// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@

(
  kzalloc(sizeof(THING) * C2, ...)
|
  kzalloc(sizeof(TYPE) * C2, ...)
|
  kzalloc(C1 * C2 * C3, ...)
|
  kzalloc(C1 * C2, ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * (E2)
+	E2, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(TYPE) * E2
+	E2, sizeof(TYPE)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * (E2)
+	E2, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	sizeof(THING) * E2
+	E2, sizeof(THING)
  , ...)
|
- kzalloc
+ kcalloc
  (
-	(E1) * E2
+	E1, E2
  , ...)
|
- kzalloc
+ kcalloc
  (
-	(E1) * (E2)
+	E1, E2
  , ...)
|
- kzalloc
+ kcalloc
  (
-	E1 * E2
+	E1, E2
  , ...)
)
Signed-off-by: NKees Cook <keescook@chromium.org>
      6396bb22
  21. 09 6月, 2018 1 次提交
  23. 08 6月, 2018 1 次提交
    • T
      x86/mce: Improve error message when kernel cannot recover · c7d606f5
      由 Tony Luck 提交于 
      Since we added support to add recovery from some errors inside the kernel in:

commit b2f9d678 ("x86/mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries")

we have done a less than stellar job at reporting the cause of recoverable
machine checks that occur in other parts of the kernel. The user just gets
the unhelpful message:

	mce: [Hardware Error]: Machine check: Action required: unknown MCACOD

doubly unhelpful when they check the manual for the reported IA32_MSR_STATUS.MCACOD
and see that it is listed as one of the standard recoverable values.

Add an extra rule to the MCE severity table to catch this case and report it
as:

	mce: [Hardware Error]: Machine check: Data load in unrecoverable area of kernel

Fixes: b2f9d678 ("x86/mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries")
Signed-off-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: stable@vger.kernel.org # 4.6+
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/4cc7c465150a9a48b8b9f45d0b840278e77eb9b5.1527283897.git.tony.luck@intel.com
      c7d606f5
  25. 06 6月, 2018 3 次提交
  27. 28 5月, 2018 1 次提交
  29. 23 5月, 2018 2 次提交
  31. 19 5月, 2018 8 次提交
  33. 18 5月, 2018 1 次提交
  35. 17 5月, 2018 9 次提交