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path: root/drivers/firmware/efi/libstub/random.c
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* efi/libstub: Allocate headspace in efi_get_memory_map()Jeffrey Hugo2016-09-05
| | | | | | | | | | | | | | | | | | efi_get_memory_map() allocates a buffer to store the memory map that it retrieves. This buffer may need to be reused by the client after ExitBootServices() is called, at which point allocations are not longer permitted. To support this usecase, provide the allocated buffer size back to the client, and allocate some additional headroom to account for any reasonable growth in the map that is likely to happen between the call to efi_get_memory_map() and the client reusing the buffer. Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Leif Lindholm <leif.lindholm@linaro.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
* efi: stub: add implementation of efi_random_alloc()Ard Biesheuvel2016-02-24
| | | | | | | | | | | | | | | | | This implements efi_random_alloc(), which allocates a chunk of memory of a certain size at a certain alignment, and uses the random_seed argument it receives to randomize the address of the allocation. This is implemented by iterating over the UEFI memory map, counting the number of suitable slots (aligned offsets) within each region, and picking a random number between 0 and 'number of slots - 1' to select the slot, This should guarantee that each possible offset is chosen equally likely. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* efi: stub: implement efi_get_random_bytes() based on EFI_RNG_PROTOCOLArd Biesheuvel2016-02-24
This exposes the firmware's implementation of EFI_RNG_PROTOCOL via a new function efi_get_random_bytes(). Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>