151 lines
3.7 KiB
C
151 lines
3.7 KiB
C
/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*
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* Common functions between firmware and kernel verified boot.
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* (Firmware portion)
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*/
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#include "2common.h"
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#include "2rsa.h"
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#include "2sha.h"
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#include "2sysincludes.h"
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vb2_error_t vb2_safe_memcmp(const void *s1, const void *s2, size_t size)
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{
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const unsigned char *us1 = s1;
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const unsigned char *us2 = s2;
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int result = 0;
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if (0 == size)
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return 0;
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/*
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* Code snippet without data-dependent branch due to Nate Lawson
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* (nate@root.org) of Root Labs.
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*/
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while (size--)
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result |= *us1++ ^ *us2++;
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return result != 0;
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}
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vb2_error_t vb2_align(uint8_t **ptr, uint32_t *size, uint32_t align,
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uint32_t want_size)
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{
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uintptr_t p = (uintptr_t)*ptr;
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uintptr_t offs = p & (align - 1);
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if (offs) {
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offs = align - offs;
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if (*size < offs)
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return VB2_ERROR_ALIGN_BIGGER_THAN_SIZE;
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*ptr += offs;
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*size -= offs;
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}
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if (*size < want_size)
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return VB2_ERROR_ALIGN_SIZE;
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return VB2_SUCCESS;
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}
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void vb2_workbuf_init(struct vb2_workbuf *wb, uint8_t *buf, uint32_t size)
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{
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wb->buf = buf;
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wb->size = size;
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/* Align the buffer so allocations will be aligned */
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if (vb2_align(&wb->buf, &wb->size, VB2_WORKBUF_ALIGN, 0))
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wb->size = 0;
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}
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void *vb2_workbuf_alloc(struct vb2_workbuf *wb, uint32_t size)
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{
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uint8_t *ptr = wb->buf;
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/* Round up size to work buffer alignment */
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size = vb2_wb_round_up(size);
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if (size > wb->size)
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return NULL;
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wb->buf += size;
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wb->size -= size;
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return ptr;
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}
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void *vb2_workbuf_realloc(struct vb2_workbuf *wb, uint32_t oldsize,
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uint32_t newsize)
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{
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/*
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* Just free and allocate to update the size. No need to move/copy
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* memory, since the new pointer is guaranteed to be the same as the
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* old one. The new allocation can fail, if the new size is too big.
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*/
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vb2_workbuf_free(wb, oldsize);
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return vb2_workbuf_alloc(wb, newsize);
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}
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void vb2_workbuf_free(struct vb2_workbuf *wb, uint32_t size)
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{
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/* Round up size to work buffer alignment */
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size = vb2_wb_round_up(size);
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wb->buf -= size;
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wb->size += size;
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}
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ptrdiff_t vb2_offset_of(const void *base, const void *ptr)
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{
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return (uintptr_t)ptr - (uintptr_t)base;
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}
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void *vb2_member_of(void *parent, ptrdiff_t offset)
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{
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/* TODO(kitching): vb2_assert(parent && offset) */
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return parent + offset;
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}
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vb2_error_t vb2_verify_member_inside(const void *parent, size_t parent_size,
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const void *member, size_t member_size,
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ptrdiff_t member_data_offset,
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size_t member_data_size)
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{
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const uintptr_t parent_end = (uintptr_t)parent + parent_size;
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const ptrdiff_t member_offs = vb2_offset_of(parent, member);
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const ptrdiff_t member_end_offs = member_offs + member_size;
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const ptrdiff_t data_offs = member_offs + member_data_offset;
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const ptrdiff_t data_end_offs = data_offs + member_data_size;
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/* Make sure parent doesn't wrap */
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if (parent_end < (uintptr_t)parent)
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return VB2_ERROR_INSIDE_PARENT_WRAPS;
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/*
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* Make sure the member is fully contained in the parent and doesn't
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* wrap. Use >, not >=, since member_size = 0 is possible.
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*/
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if (member_end_offs < member_offs)
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return VB2_ERROR_INSIDE_MEMBER_WRAPS;
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if (member_offs < 0 || member_offs > parent_size ||
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member_end_offs > parent_size)
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return VB2_ERROR_INSIDE_MEMBER_OUTSIDE;
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/* Make sure the member data is after the member */
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if (member_data_size > 0 && data_offs < member_end_offs)
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return VB2_ERROR_INSIDE_DATA_OVERLAP;
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/* Make sure parent fully contains member data, if any */
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if (data_end_offs < data_offs)
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return VB2_ERROR_INSIDE_DATA_WRAPS;
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if (data_offs < 0 || data_offs > parent_size ||
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data_end_offs > parent_size)
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return VB2_ERROR_INSIDE_DATA_OUTSIDE;
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return VB2_SUCCESS;
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}
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