linux.git/arch/x86/kernel/vmlinux.lds.S, branch v5.6

x86/vdso: Provide vdso_data offset on vvar_page

2020-01-14T11:20:57+00:00

VDSO support for time namespaces needs to set up a page with the same
layout as VVAR. That timens page will be placed on position of VVAR page
inside namespace. That page has vdso_data->seq set to 1 to enforce
the slow path and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce
the time namespace handling path.

To prepare the time namespace page the kernel needs to know the vdso_data
offset.  Provide arch_get_vdso_data() helper for locating vdso_data on VVAR
page.

Co-developed-by: Andrei Vagin 
Signed-off-by: Andrei Vagin 
Signed-off-by: Dmitry Safonov 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20191112012724.250792-22-dima@arista.com

x86/vmlinux: Use INT3 instead of NOP for linker fill bytes

2019-11-04T18:10:08+00:00

Instead of using 0x90 (NOP) to fill bytes between functions, which makes
it easier to sloppily target functions in function pointer overwrite
attacks, fill with 0xCC (INT3) to force a trap. Also drop the space
between "=" and the value to better match the binutils documentation

  https://sourceware.org/binutils/docs/ld/Output-Section-Fill.html#Output-Section-Fill

Example "objdump -d" before:

  ...
  ffffffff810001e0 :
  ffffffff810001e0:       48 8b 25 e1 b1 51 01    mov 0x151b1e1(%rip),%rsp        # ffffffff8251b3c8 
  ffffffff810001e7:       e9 d5 fe ff ff          jmpq   ffffffff810000c1 
  ffffffff810001ec:       90                      nop
  ffffffff810001ed:       90                      nop
  ffffffff810001ee:       90                      nop
  ffffffff810001ef:       90                      nop

  ffffffff810001f0 <__startup_64>:
  ...

After:

  ...
  ffffffff810001e0 :
  ffffffff810001e0:       48 8b 25 41 79 53 01    mov 0x1537941(%rip),%rsp        # ffffffff82537b28 
  ffffffff810001e7:       e9 d5 fe ff ff          jmpq   ffffffff810000c1 
  ffffffff810001ec:       cc                      int3
  ffffffff810001ed:       cc                      int3
  ffffffff810001ee:       cc                      int3
  ffffffff810001ef:       cc                      int3

  ffffffff810001f0 <__startup_64>:
  ...

Signed-off-by: Kees Cook 
Signed-off-by: Borislav Petkov 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Dave Hansen 
Cc: Heiko Carstens 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Rick Edgecombe 
Cc: Ross Zwisler 
Cc: Segher Boessenkool 
Cc: Thomas Gleixner 
Cc: Thomas Lendacky 
Cc: Will Deacon 
Cc: x86-ml 
Cc: Yoshinori Sato 
Link: https://lkml.kernel.org/r/20191029211351.13243-30-keescook@chromium.org

x86/vmlinux: Move EXCEPTION_TABLE to RO_DATA segment

2019-11-04T16:55:02+00:00

The exception table was needlessly marked executable. In preparation
for execute-only memory, move the table into the RO_DATA segment via
the new macro that can be used by any architectures that want to make
a similar consolidation.

Signed-off-by: Kees Cook 
Signed-off-by: Borislav Petkov 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Dave Hansen 
Cc: Heiko Carstens 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Rick Edgecombe 
Cc: Ross Zwisler 
Cc: Segher Boessenkool 
Cc: Thomas Gleixner 
Cc: Thomas Lendacky 
Cc: Will Deacon 
Cc: x86-ml 
Cc: Yoshinori Sato 
Link: https://lkml.kernel.org/r/20191029211351.13243-17-keescook@chromium.org

x86/vmlinux: Actually use _etext for the end of the text segment

2019-11-04T16:54:16+00:00

Various calculations are using the end of the exception table (which
does not need to be executable) as the end of the text segment. Instead,
in preparation for moving the exception table into RO_DATA, move _etext
after the exception table and update the calculations.

Signed-off-by: Kees Cook 
Signed-off-by: Borislav Petkov 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Dave Hansen 
Cc: Heiko Carstens 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Nick Desaulniers 
Cc: Peter Zijlstra 
Cc: Rick Edgecombe 
Cc: Ross Zwisler 
Cc: Segher Boessenkool 
Cc: Thomas Gleixner 
Cc: Thomas Lendacky 
Cc: Will Deacon 
Cc: x86-ml 
Cc: Yoshinori Sato 
Link: https://lkml.kernel.org/r/20191029211351.13243-16-keescook@chromium.org

vmlinux.lds.h: Move NOTES into RO_DATA

2019-11-04T14:34:41+00:00

The .notes section should be non-executable read-only data. As such,
move it to the RO_DATA macro instead of being per-architecture defined.

Signed-off-by: Kees Cook 
Signed-off-by: Borislav Petkov 
Acked-by: Heiko Carstens  # s390
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Dave Hansen 
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Rick Edgecombe 
Cc: Segher Boessenkool 
Cc: Will Deacon 
Cc: x86-ml 
Cc: Yoshinori Sato 
Link: https://lkml.kernel.org/r/20191029211351.13243-11-keescook@chromium.org

vmlinux.lds.h: Move Program Header restoration into NOTES macro

2019-11-04T14:34:39+00:00

In preparation for moving NOTES into RO_DATA, make the Program Header
assignment restoration be part of the NOTES macro itself.

Signed-off-by: Kees Cook 
Signed-off-by: Borislav Petkov 
Acked-by: Heiko Carstens  # s390
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Dave Hansen 
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Rick Edgecombe 
Cc: Segher Boessenkool 
Cc: Will Deacon 
Cc: x86-ml 
Cc: Yoshinori Sato 
Link: https://lkml.kernel.org/r/20191029211351.13243-10-keescook@chromium.org

vmlinux.lds.h: Provide EMIT_PT_NOTE to indicate export of .notes

2019-11-04T14:34:38+00:00

In preparation for moving NOTES into RO_DATA, provide a mechanism for
architectures that want to emit a PT_NOTE Program Header to do so.

Signed-off-by: Kees Cook 
Signed-off-by: Borislav Petkov 
Acked-by: Heiko Carstens  # s390
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Dave Hansen 
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Rick Edgecombe 
Cc: Segher Boessenkool 
Cc: Will Deacon 
Cc: x86-ml 
Cc: Yoshinori Sato 
Link: https://lkml.kernel.org/r/20191029211351.13243-9-keescook@chromium.org

x86/vmlinux: Restore "text" Program Header with dummy section

2019-11-04T14:34:36+00:00

In a linker script, if one places a section in one or more segments using
":PHDR", then the linker will place all subsequent allocatable sections,
which do not specify ":PHDR", into the same segments. In order to have
the NOTES section in both PT_LOAD (":text") and PT_NOTE (":note"), both
segments are marked, and the only way to undo this to keep subsequent
sections out of PT_NOTE is to mark the following section with just the
single desired PT_LOAD (":text").

In preparation for having a common NOTES macro, perform the segment
assignment using a dummy section (as done by other architectures).

Signed-off-by: Kees Cook 
Signed-off-by: Borislav Petkov 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Dave Hansen 
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Rick Edgecombe 
Cc: Segher Boessenkool 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Cc: x86-ml 
Link: https://lkml.kernel.org/r/20191029211351.13243-8-keescook@chromium.org

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-07-11T20:54:00+00:00

Pull x86 fixes from Thomas Gleixner:
 "A collection of assorted fixes:

   - Fix for the pinned cr0/4 fallout which escaped all testing efforts
     because the kvm-intel module was never loaded when the kernel was
     compiled with CONFIG_PARAVIRT=n. The cr0/4 accessors are moved out
     of line and static key is now solely used in the core code and
     therefore can stay in the RO after init section. So the kvm-intel
     and other modules do not longer reference the (read only) static
     key which the module loader tried to update.

   - Prevent an infinite loop in arch_stack_walk_user() by breaking out
     of the loop once the return address is detected to be 0.

   - Prevent the int3_emulate_call() selftest from corrupting the stack
     when KASAN is enabled. KASASN clobbers more registers than covered
     by the emulated call implementation. Convert the int3_magic()
     selftest to a ASM function so the compiler cannot KASANify it.

   - Unbreak the build with old GCC versions and with the Gold linker by
     reverting the 'Move of _etext to the actual end of .text'. In both
     cases the build fails with 'Invalid absolute R_X86_64_32S
     relocation: _etext'

   - Initialize the context lock for init_mm, which was never an issue
     until the alternatives code started to use a temporary mm for
     patching.

   - Fix a build warning vs. the LOWMEM_PAGES constant where clang
     complains rightfully about a signed integer overflow in the shift
     operation by converting the operand to an ULL.

   - Adjust the misnamed ENDPROC() of common_spurious in the 32bit entry
     code"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/stacktrace: Prevent infinite loop in arch_stack_walk_user()
  x86/asm: Move native_write_cr0/4() out of line
  x86/pgtable/32: Fix LOWMEM_PAGES constant
  x86/alternatives: Fix int3_emulate_call() selftest stack corruption
  x86/entry/32: Fix ENDPROC of common_spurious
  Revert "x86/build: Move _etext to actual end of .text"
  x86/ldt: Initialize the context lock for init_mm

Revert "x86/build: Move _etext to actual end of .text"

2019-07-09T11:57:31+00:00

This reverts commit 392bef709659abea614abfe53cf228e7a59876a4.

Per the discussion here:

  https://lkml.kernel.org/r/201906201042.3BF5CD6@keescook

the above referenced commit breaks kernel compilation with old GCC
toolchains as well as current versions of the Gold linker.

Revert it to fix the regression and to keep the ability to compile the
kernel with these tools.

Signed-off-by: Ross Zwisler 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Guenter Roeck 
Cc: 
Cc: "H. Peter Anvin" 
Cc: Borislav Petkov 
Cc: Kees Cook 
Cc: Johannes Hirte 
Cc: Klaus Kusche 
Cc: samitolvanen@google.com
Cc: Guenter Roeck 
Link: https://lkml.kernel.org/r/20190701155208.211815-1-zwisler@google.com
Signed-off-by: Ingo Molnar