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