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Groups > linux.kernel > #1288010
| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v3 8/8] x86, vdso: mark vDSO read-only after init |
| Date | 2015-12-10 00:20 +0100 |
| Message-ID | <qDWbF-6rH-37@gated-at.bofh.it> (permalink) |
| References | <qDUMz-5qy-13@gated-at.bofh.it> <qDUMA-5qy-51@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, Dec 9, 2015 at 1:43 PM, Kees Cook <keescook@chromium.org> wrote: > The vDSO does not need to be writable after __init, so mark it as > __ro_after_init. The result kills the exploit method of writing to the > vDSO from kernel space resulting in userspace executing the modified code, > as shown here to bypass SMEP restrictions: http://itszn.com/blog/?p=21 > > The memory map (with added vDSO address reporting) shows the vDSO moving > into read-only memory: > > Before: > [ 0.143067] vDSO @ ffffffff82004000 > [ 0.143551] vDSO @ ffffffff82006000 > ---[ High Kernel Mapping ]--- > 0xffffffff80000000-0xffffffff81000000 16M pmd > 0xffffffff81000000-0xffffffff81800000 8M ro PSE GLB x pmd > 0xffffffff81800000-0xffffffff819f3000 1996K ro GLB x pte > 0xffffffff819f3000-0xffffffff81a00000 52K ro NX pte > 0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd > 0xffffffff81e00000-0xffffffff81e05000 20K ro GLB NX pte > 0xffffffff81e05000-0xffffffff82000000 2028K ro NX pte > 0xffffffff82000000-0xffffffff8214f000 1340K RW GLB NX pte > 0xffffffff8214f000-0xffffffff82281000 1224K RW NX pte > 0xffffffff82281000-0xffffffff82400000 1532K RW GLB NX pte > 0xffffffff82400000-0xffffffff83200000 14M RW PSE GLB NX pmd > 0xffffffff83200000-0xffffffffc0000000 974M pmd > > After: > [ 0.145062] vDSO @ ffffffff81da1000 > [ 0.146057] vDSO @ ffffffff81da4000 > ---[ High Kernel Mapping ]--- > 0xffffffff80000000-0xffffffff81000000 16M pmd > 0xffffffff81000000-0xffffffff81800000 8M ro PSE GLB x pmd > 0xffffffff81800000-0xffffffff819f3000 1996K ro GLB x pte > 0xffffffff819f3000-0xffffffff81a00000 52K ro NX pte > 0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd > 0xffffffff81e00000-0xffffffff81e0b000 44K ro GLB NX pte > 0xffffffff81e0b000-0xffffffff82000000 2004K ro NX pte > 0xffffffff82000000-0xffffffff8214c000 1328K RW GLB NX pte > 0xffffffff8214c000-0xffffffff8227e000 1224K RW NX pte > 0xffffffff8227e000-0xffffffff82400000 1544K RW GLB NX pte > 0xffffffff82400000-0xffffffff83200000 14M RW PSE GLB NX pmd > 0xffffffff83200000-0xffffffffc0000000 974M pmd > > Based on work by PaX Team and Brad Spengler. > > Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Andy Lutomirski <luto@kernel.org> --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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[PATCH v3 0/8] introduce post-init read-only memory Kees Cook <keescook@chromium.org> - 2015-12-09 22:50 +0100
[PATCH v3 4/8] init: create cmdline param to disable readonly Kees Cook <keescook@chromium.org> - 2015-12-09 22:50 +0100
[PATCH v3 1/8] asm-generic: consolidate mark_rodata_ro() Kees Cook <keescook@chromium.org> - 2015-12-09 22:50 +0100
[PATCH v3 8/8] x86, vdso: mark vDSO read-only after init Kees Cook <keescook@chromium.org> - 2015-12-09 22:50 +0100
Re: [PATCH v3 8/8] x86, vdso: mark vDSO read-only after init Andy Lutomirski <luto@amacapital.net> - 2015-12-10 00:20 +0100
Re: [PATCH v3 8/8] x86, vdso: mark vDSO read-only after init Andy Lutomirski <luto@amacapital.net> - 2015-12-11 02:40 +0100
[PATCH v3 5/8] x86: make CONFIG_DEBUG_RODATA non-optional Kees Cook <keescook@chromium.org> - 2015-12-09 22:50 +0100
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