Messages in this thread | | | From | Andy Lutomirski <> | Subject | [PATCH v6 0/4] x86: modify_ldt improvement, test, and config option | Date | Thu, 30 Jul 2015 14:31:30 -0700 |
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This is intended for x86/urgent. Sorry for taking so long, but it seemed nice to avoid breaking Xen.
This fixes the "dazed and confused" issue which was exposed by the CVE-2015-5157 fix. 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 test patch 1? It works for me on my evil 32-bit Xen virtio setup.
Willy and Kees: I left the config option alone. The -tiny people will like it, and we can always add a sysctl of some sort later.
Changes from v5: - Improve Xen bits, this time with comments that seem plausible. - Fix debug_locks warning on exec. - Add a test for exec preserving the LDT (!)
Changes from v4: - Fix Xen even better (patch 1 is new). - Reorder the patches to make a little more sense.
Changes from v3: - Hopefully fixed Xen. - Fixed 32-bit test case on 32-bit native kernel. - Fix bogus vumnap for some LDT sizes. - Strengthen test case to check all LDT sizes (catches bogus vunmap). - Lots of cleanups, mostly from Borislav. - Simplify IPI code using on_each_cpu_mask.
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 (4): x86/xen: Probe target addresses in set_aliased_prot before the hypercall x86/ldt: Make modify_ldt synchronous selftests/x86, x86/ldt: Add a selftest for modify_ldt x86/ldt: Make modify_ldt optional
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 | 262 +++++++++------- arch/x86/kernel/process_64.c | 6 +- arch/x86/kernel/step.c | 8 +- arch/x86/power/cpu.c | 3 +- arch/x86/xen/enlighten.c | 40 +++ kernel/sys_ni.c | 1 + tools/testing/selftests/x86/Makefile | 2 +- tools/testing/selftests/x86/ldt_gdt.c | 576 ++++++++++++++++++++++++++++++++++ 15 files changed, 871 insertions(+), 155 deletions(-) create mode 100644 tools/testing/selftests/x86/ldt_gdt.c
-- 2.4.3
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