88d8a7994e
Although the arm64 vDSO is cleanly separated by code/data with the code being read-only in userspace mappings, the code page is still writable from the kernel. There have been exploits (such as http://itszn.com/blog/?p=21) that take advantage of this on x86 to go from a bad kernel write to full root. Prevent this specific exploit on arm64 by putting the vDSO code page in read-only memory as well. Before the change: [ 3.138366] vdso: 2 pages (1 code @ ffffffc000a71000, 1 data @ ffffffc000a70000) ---[ Kernel Mapping ]--- 0xffffffc000000000-0xffffffc000082000 520K RW NX SHD AF UXN MEM/NORMAL 0xffffffc000082000-0xffffffc000200000 1528K ro x SHD AF UXN MEM/NORMAL 0xffffffc000200000-0xffffffc000800000 6M ro x SHD AF BLK UXN MEM/NORMAL 0xffffffc000800000-0xffffffc0009b6000 1752K ro x SHD AF UXN MEM/NORMAL 0xffffffc0009b6000-0xffffffc000c00000 2344K RW NX SHD AF UXN MEM/NORMAL 0xffffffc000c00000-0xffffffc008000000 116M RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc00c000000-0xffffffc07f000000 1840M RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc800000000-0xffffffc840000000 1G RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc840000000-0xffffffc87ae00000 942M RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc87ae00000-0xffffffc87ae70000 448K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87af80000-0xffffffc87af8a000 40K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87af8b000-0xffffffc87b000000 468K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87b000000-0xffffffc87fe00000 78M RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc87fe00000-0xffffffc87ff50000 1344K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87ff90000-0xffffffc87ffa0000 64K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87fff0000-0xffffffc880000000 64K RW NX SHD AF UXN MEM/NORMAL After: [ 3.138368] vdso: 2 pages (1 code @ ffffffc0006de000, 1 data @ ffffffc000a74000) ---[ Kernel Mapping ]--- 0xffffffc000000000-0xffffffc000082000 520K RW NX SHD AF UXN MEM/NORMAL 0xffffffc000082000-0xffffffc000200000 1528K ro x SHD AF UXN MEM/NORMAL 0xffffffc000200000-0xffffffc000800000 6M ro x SHD AF BLK UXN MEM/NORMAL 0xffffffc000800000-0xffffffc0009b8000 1760K ro x SHD AF UXN MEM/NORMAL 0xffffffc0009b8000-0xffffffc000c00000 2336K RW NX SHD AF UXN MEM/NORMAL 0xffffffc000c00000-0xffffffc008000000 116M RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc00c000000-0xffffffc07f000000 1840M RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc800000000-0xffffffc840000000 1G RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc840000000-0xffffffc87ae00000 942M RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc87ae00000-0xffffffc87ae70000 448K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87af80000-0xffffffc87af8a000 40K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87af8b000-0xffffffc87b000000 468K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87b000000-0xffffffc87fe00000 78M RW NX SHD AF BLK UXN MEM/NORMAL 0xffffffc87fe00000-0xffffffc87ff50000 1344K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87ff90000-0xffffffc87ffa0000 64K RW NX SHD AF UXN MEM/NORMAL 0xffffffc87fff0000-0xffffffc880000000 64K RW NX SHD AF UXN MEM/NORMAL Inspired by https://lkml.org/lkml/2016/1/19/494 based on work by the PaX Team, Brad Spengler, and Kees Cook. Signed-off-by: David Brown <david.brown@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> [catalin.marinas@arm.com: removed superfluous __PAGE_ALIGNED_DATA] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> |
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| .. | ||
| .gitignore | ||
| Makefile | ||
| gen_vdso_offsets.sh | ||
| gettimeofday.S | ||
| note.S | ||
| sigreturn.S | ||
| vdso.S | ||
| vdso.lds.S | ||