* [PATCH v3 0/3] x86: modify_ldt improvement, test, and config option
@ 2015-07-22 19:23 Andy Lutomirski
0 siblings, 0 replies; only message in thread
From: Andy Lutomirski @ 2015-07-22 19:23 UTC (permalink / raw)
To: Peter Zijlstra, Steven Rostedt
Cc: security, Andy Lutomirski, Andrew Cooper, X86 ML, linux-kernel,
xen-devel, Borislav Petkov, Jan Beulich, Sasha Levin,
Boris Ostrovsky
Here's v3. It fixes the "dazed and confused" issue, I hope. It's also
probably a good general attack surface reduction, and it replaces some
scary code with IMO less scary code.
Also, servers and embedded systems should probably turn off modify_ldt.
This makes that possible.
Xen people, can you take a look at this?
Changes from v2:
- Allocate ldt_struct and the LDT entries separately. This should fix Xen.
- Stop using write_ldt_entry, since I'm pretty sure it's unnecessary now
that we no longer mutate an in-use LDT. (Xen people, can you check?)
Changes from v1:
- The config option is new.
- The test case is new.
- Fixed a missing allocation failure check.
- Fixed a use-after-free on fork().
Andy Lutomirski (3):
x86/ldt: Make modify_ldt synchronous
x86/ldt: Make modify_ldt optional
selftests/x86, x86/ldt: Add a selftest for modify_ldt
arch/x86/Kconfig | 17 ++
arch/x86/include/asm/desc.h | 15 --
arch/x86/include/asm/mmu.h | 5 +-
arch/x86/include/asm/mmu_context.h | 68 ++++-
arch/x86/kernel/Makefile | 3 +-
arch/x86/kernel/cpu/common.c | 4 +-
arch/x86/kernel/cpu/perf_event.c | 16 +-
arch/x86/kernel/ldt.c | 258 ++++++++++--------
arch/x86/kernel/process_64.c | 6 +-
arch/x86/kernel/step.c | 8 +-
arch/x86/power/cpu.c | 3 +-
kernel/sys_ni.c | 1 +
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/ldt_gdt.c | 492 ++++++++++++++++++++++++++++++++++
14 files changed, 747 insertions(+), 151 deletions(-)
create mode 100644 tools/testing/selftests/x86/ldt_gdt.c
--
2.4.3
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