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  */
7 
8 #ifndef VBOOT_REFERENCE_VBOOT_2COMMON_H_
9 #define VBOOT_REFERENCE_VBOOT_2COMMON_H_
10 
11 #include "2api.h"
12 #include "2return_codes.h"
13 #include "2sha.h"
14 #include "2struct.h"
15 
16 struct vb2_public_key;
17 
18 /*
19  * Return the greater of A and B.  This is used in macros which calculate the
20  * required buffer size, so can't be turned into a static inline function.
21  */
22 #ifndef VB2_MAX
23 #define VB2_MAX(A, B) ((A) > (B) ? (A) : (B))
24 #endif
25 
26 /* Return the number of elements in an array */
27 #ifndef ARRAY_SIZE
28 #define ARRAY_SIZE(array) (sizeof(array)/sizeof(array[0]))
29 #endif
30 
31 /* Debug output printf() for tests.  Otherwise, it's platform-dependent. */
32 #if defined(VBOOT_DEBUG)
33 #  if defined(FOR_TEST)
34 #    define VB2_DEBUG(format, args...) printf(format, ## args)
35 #  else
36 #    define VB2_DEBUG(format, args...) vb2ex_printf(__func__, format, ## args)
37 #  endif
38 #else
39 #  define VB2_DEBUG(format, args...)
40 #endif
41 
42 /*
43  * Alignment for work buffer pointers/allocations should be useful for any
44  * data type. When declaring workbuf buffers on the stack, the caller should
45  * use explicit alignment to avoid run-time errors. For example:
46  *
47  *    int foo(void)
48  *    {
49  *        struct vb2_workbuf wb;
50  *        uint8_t buf[NUM] __attribute__ ((aligned (VB2_WORKBUF_ALIGN)));
51  *        wb.buf = buf;
52  *        wb.size = sizeof(buf);
53  */
54 
55 /* We might get away with using __alignof__(void *), but since GCC defines a
56  * macro for us we'll be safe and use that. */
57 #define VB2_WORKBUF_ALIGN __BIGGEST_ALIGNMENT__
58 
59 /* Work buffer */
60 struct vb2_workbuf {
61 	uint8_t *buf;
62 	uint32_t size;
63 };
64 
65 /**
66  * Initialize a work buffer.
67  *
68  * @param wb		Work buffer to init
69  * @param buf		Pointer to work buffer data
70  * @param size		Size of work buffer data in bytes
71  */
72 void vb2_workbuf_init(struct vb2_workbuf *wb, uint8_t *buf, uint32_t size);
73 
74 /**
75  * Allocate space in a work buffer.
76  *
77  * Note that the returned buffer will always be aligned to VB2_WORKBUF_ALIGN.
78  *
79  * The work buffer acts like a stack, and detailed tracking of allocs and frees
80  * is not done.  The caller must track the size of each allocation and free via
81  * vb2_workbuf_free() in the reverse order they were allocated.
82  *
83  * An acceptable alternate workflow inside a function is to pass in a const
84  * work buffer, then make a local copy.  Allocations done to the local copy
85  * then don't change the passed-in work buffer, and will effectively be freed
86  * when the local copy goes out of scope.
87  *
88  * @param wb		Work buffer
89  * @param size		Requested size in bytes
90  * @return A pointer to the allocated space, or NULL if error.
91  */
92 void *vb2_workbuf_alloc(struct vb2_workbuf *wb, uint32_t size);
93 
94 /**
95  * Reallocate space in a work buffer.
96  *
97  * Note that the returned buffer will always be aligned to VB2_WORKBUF_ALIGN.
98  * The work buffer acts like a stack, so this must only be done to the most
99  * recently allocated buffer.
100  *
101  * @param wb		Work buffer
102  * @param oldsize	Old allocation size in bytes
103  * @param newsize	Requested size in bytes
104  * @return A pointer to the allocated space, or NULL if error.
105  */
106 void *vb2_workbuf_realloc(struct vb2_workbuf *wb,
107 			  uint32_t oldsize,
108 			  uint32_t newsize);
109 
110 /**
111  * Free the preceding allocation.
112  *
113  * Note that the work buffer acts like a stack, and detailed tracking of
114  * allocs and frees is not done.  The caller must track the size of each
115  * allocation and free them in reverse order.
116  *
117  * @param wb		Work buffer
118  * @param size		Size of data to free
119  */
120 void vb2_workbuf_free(struct vb2_workbuf *wb, uint32_t size);
121 
122 /* Check if a pointer is aligned on an align-byte boundary */
123 #define vb2_aligned(ptr, align) (!(((uintptr_t)(ptr)) & ((align) - 1)))
124 
125 /**
126  * Safer memcmp() for use in crypto.
127  *
128  * Compares the buffers to see if they are equal.  Time taken to perform
129  * the comparison is dependent only on the size, not the relationship of
130  * the match between the buffers.  Note that unlike memcmp(), this only
131  * indicates inequality, not which buffer is lesser.
132  *
133  * @param s1		First buffer
134  * @param s2		Second buffer
135  * @param size		Number of bytes to compare
136  * @return 0 if match or size=0, non-zero if at least one byte mismatched.
137  */
138 int vb2_safe_memcmp(const void *s1, const void *s2, size_t size);
139 
140 /**
141  * Align a buffer and check its size.
142  *
143  * @param **ptr		Pointer to pointer to align
144  * @param *size		Points to size of buffer pointed to by *ptr
145  * @param align		Required alignment (must be power of 2)
146  * @param want_size	Required size
147  * @return VB2_SUCCESS, or non-zero if error.
148  */
149 int vb2_align(uint8_t **ptr,
150 	      uint32_t *size,
151 	      uint32_t align,
152 	      uint32_t want_size);
153 
154 /**
155  * Return offset of ptr from base.
156  *
157  * @param base		Base pointer
158  * @param ptr		Pointer at some offset from base
159  * @return The offset of ptr from base.
160  */
161 ptrdiff_t vb2_offset_of(const void *base, const void *ptr);
162 
163 /**
164  * Return expected signature size for a signature/hash algorithm pair
165  *
166  * @param sig_alg	Signature algorithm
167  * @param hash_alg	Hash algorithm
168  * @return The signature size, or zero if error / unsupported algorithm.
169  */
170 uint32_t vb2_sig_size(enum vb2_signature_algorithm sig_alg,
171 		      enum vb2_hash_algorithm hash_alg);
172 
173 /**
174  * Return a key guid for an unsigned hash algorithm.
175  *
176  * @param hash_alg	Hash algorithm to return key for
177  * @return A pointer to the key guid for that hash algorithm and
178  *	   sig_alg=VB2_SIG_NONE, or NULL if error.
179  */
180 const struct vb2_guid *vb2_hash_guid(enum vb2_hash_algorithm hash_alg);
181 
182 /* Size of work buffer sufficient for vb2_verify_digest() worst case. */
183 #define VB2_VERIFY_DIGEST_WORKBUF_BYTES VB2_VERIFY_RSA_DIGEST_WORKBUF_BYTES
184 
185 /* Size of work buffer sufficient for vb2_verify_data() worst case. */
186 #define VB2_VERIFY_DATA_WORKBUF_BYTES					\
187 	(VB2_SHA512_DIGEST_SIZE +					\
188 	 VB2_MAX(VB2_VERIFY_DIGEST_WORKBUF_BYTES,			\
189 		 sizeof(struct vb2_digest_context)))
190 
191 /* Size of work buffer sufficient for vb2_verify_keyblock() worst case. */
192 #define VB2_KEY_BLOCK_VERIFY_WORKBUF_BYTES VB2_VERIFY_DATA_WORKBUF_BYTES
193 
194 /* Size of work buffer sufficient for vb2_verify_fw_preamble() worst case. */
195 #define VB2_VERIFY_FIRMWARE_PREAMBLE_WORKBUF_BYTES VB2_VERIFY_DATA_WORKBUF_BYTES
196 
197 #endif  /* VBOOT_REFERENCE_VBOOT_2COMMON_H_ */
198