1/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
2 * Use of this source code is governed by a BSD-style license that can be
3 * found in the LICENSE file.
4 *
5 * Common functions between firmware and kernel verified boot.
6 * (Firmware portion)
7 */
8
9#include "2sysincludes.h"
10#include "2common.h"
11#include "2rsa.h"
12#include "2sha.h"
13
14int vb2_safe_memcmp(const void *s1, const void *s2, size_t size)
15{
16	const unsigned char *us1 = s1;
17	const unsigned char *us2 = s2;
18	int result = 0;
19
20	if (0 == size)
21		return 0;
22
23	/*
24	 * Code snippet without data-dependent branch due to Nate Lawson
25	 * (nate@root.org) of Root Labs.
26	 */
27	while (size--)
28		result |= *us1++ ^ *us2++;
29
30	return result != 0;
31}
32
33int vb2_align(uint8_t **ptr, uint32_t *size, uint32_t align, uint32_t want_size)
34{
35	uintptr_t p = (uintptr_t)*ptr;
36	uintptr_t offs = p & (align - 1);
37
38	if (offs) {
39		offs = align - offs;
40
41		if (*size < offs)
42			return VB2_ERROR_ALIGN_BIGGER_THAN_SIZE;
43
44		*ptr += offs;
45		*size -= offs;
46	}
47
48	if (*size < want_size)
49		return VB2_ERROR_ALIGN_SIZE;
50
51	return VB2_SUCCESS;
52}
53
54void vb2_workbuf_init(struct vb2_workbuf *wb, uint8_t *buf, uint32_t size)
55{
56	wb->buf = buf;
57	wb->size = size;
58
59	/* Align the buffer so allocations will be aligned */
60	if (vb2_align(&wb->buf, &wb->size, VB2_WORKBUF_ALIGN, 0))
61		wb->size = 0;
62}
63
64/**
65 * Round up a number to a multiple of VB2_WORKBUF_ALIGN
66 *
67 * @param v		Number to round up
68 * @return The number, rounded up.
69 */
70static __inline uint32_t wb_round_up(uint32_t v)
71{
72	return (v + VB2_WORKBUF_ALIGN - 1) & ~(VB2_WORKBUF_ALIGN - 1);
73}
74
75void *vb2_workbuf_alloc(struct vb2_workbuf *wb, uint32_t size)
76{
77	uint8_t *ptr = wb->buf;
78
79	/* Round up size to work buffer alignment */
80	size = wb_round_up(size);
81
82	if (size > wb->size)
83		return NULL;
84
85	wb->buf += size;
86	wb->size -= size;
87
88	return ptr;
89}
90
91void *vb2_workbuf_realloc(struct vb2_workbuf *wb,
92			  uint32_t oldsize,
93			  uint32_t newsize)
94{
95	/*
96	 * Just free and allocate to update the size.  No need to move/copy
97	 * memory, since the new pointer is guaranteed to be the same as the
98	 * old one.  The new allocation can fail, if the new size is too big.
99	 */
100	vb2_workbuf_free(wb, oldsize);
101	return vb2_workbuf_alloc(wb, newsize);
102}
103
104void vb2_workbuf_free(struct vb2_workbuf *wb, uint32_t size)
105{
106	/* Round up size to work buffer alignment */
107	size = wb_round_up(size);
108
109	wb->buf -= size;
110	wb->size += size;
111}
112
113ptrdiff_t vb2_offset_of(const void *base, const void *ptr)
114{
115	return (uintptr_t)ptr - (uintptr_t)base;
116}
117