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
vb2_safe_memcmp(const void * s1,const void * s2,size_t size)14 int 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
vb2_align(uint8_t ** ptr,uint32_t * size,uint32_t align,uint32_t want_size)33 int 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
vb2_workbuf_init(struct vb2_workbuf * wb,uint8_t * buf,uint32_t size)54 void 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 */
wb_round_up(uint32_t v)70 static __inline uint32_t wb_round_up(uint32_t v)
71 {
72 return (v + VB2_WORKBUF_ALIGN - 1) & ~(VB2_WORKBUF_ALIGN - 1);
73 }
74
vb2_workbuf_alloc(struct vb2_workbuf * wb,uint32_t size)75 void *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
vb2_workbuf_realloc(struct vb2_workbuf * wb,uint32_t oldsize,uint32_t newsize)91 void *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
vb2_workbuf_free(struct vb2_workbuf * wb,uint32_t size)104 void 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
vb2_offset_of(const void * base,const void * ptr)113 ptrdiff_t vb2_offset_of(const void *base, const void *ptr)
114 {
115 return (uintptr_t)ptr - (uintptr_t)base;
116 }
117