1=pod
2
3=head1 NAME
4
5CRYPTO_secure_malloc_init, CRYPTO_secure_malloc_initialized,
6CRYPTO_secure_malloc_done, OPENSSL_secure_malloc, CRYPTO_secure_malloc,
7OPENSSL_secure_zalloc, CRYPTO_secure_zalloc, OPENSSL_secure_free,
8CRYPTO_secure_free, OPENSSL_secure_clear_free,
9CRYPTO_secure_clear_free, OPENSSL_secure_actual_size,
10CRYPTO_secure_used - secure heap storage
11
12=head1 SYNOPSIS
13
14 #include <openssl/crypto.h>
15
16 int CRYPTO_secure_malloc_init(size_t size, int minsize);
17
18 int CRYPTO_secure_malloc_initialized();
19
20 int CRYPTO_secure_malloc_done();
21
22 void *OPENSSL_secure_malloc(size_t num);
23 void *CRYPTO_secure_malloc(size_t num, const char *file, int line);
24
25 void *OPENSSL_secure_zalloc(size_t num);
26 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line);
27
28 void OPENSSL_secure_free(void* ptr);
29 void CRYPTO_secure_free(void *ptr, const char *, int);
30
31 void OPENSSL_secure_clear_free(void* ptr, size_t num);
32 void CRYPTO_secure_clear_free(void *ptr, size_t num, const char *, int);
33
34 size_t OPENSSL_secure_actual_size(const void *ptr);
35
36 size_t CRYPTO_secure_used();
37
38=head1 DESCRIPTION
39
40In order to help protect applications (particularly long-running servers)
41from pointer overruns or underruns that could return arbitrary data from
42the program's dynamic memory area, where keys and other sensitive
43information might be stored, OpenSSL supports the concept of a "secure heap."
44The level and type of security guarantees depend on the operating system.
45It is a good idea to review the code and see if it addresses your
46threat model and concerns.
47
48If a secure heap is used, then private key B<BIGNUM> values are stored there.
49This protects long-term storage of private keys, but will not necessarily
50put all intermediate values and computations there.
51
52CRYPTO_secure_malloc_init() creates the secure heap, with the specified
53C<size> in bytes. The C<minsize> parameter is the minimum size to
54allocate from the heap. Both C<size> and C<minsize> must be a power
55of two.
56
57CRYPTO_secure_malloc_initialized() indicates whether or not the secure
58heap as been initialized and is available.
59
60CRYPTO_secure_malloc_done() releases the heap and makes the memory unavailable
61to the process if all secure memory has been freed.
62It can take noticeably long to complete.
63
64OPENSSL_secure_malloc() allocates C<num> bytes from the heap.
65If CRYPTO_secure_malloc_init() is not called, this is equivalent to
66calling OPENSSL_malloc().
67It is a macro that expands to
68CRYPTO_secure_malloc() and adds the C<__FILE__> and C<__LINE__> parameters.
69
70OPENSSL_secure_zalloc() and CRYPTO_secure_zalloc() are like
71OPENSSL_secure_malloc() and CRYPTO_secure_malloc(), respectively,
72except that they call memset() to zero the memory before returning.
73
74OPENSSL_secure_free() releases the memory at C<ptr> back to the heap.
75It must be called with a value previously obtained from
76OPENSSL_secure_malloc().
77If CRYPTO_secure_malloc_init() is not called, this is equivalent to
78calling OPENSSL_free().
79It exists for consistency with OPENSSL_secure_malloc() , and
80is a macro that expands to CRYPTO_secure_free() and adds the C<__FILE__>
81and C<__LINE__> parameters..
82
83OPENSSL_secure_clear_free() is similar to OPENSSL_secure_free() except
84that it has an additional C<num> parameter which is used to clear
85the memory if it was not allocated from the secure heap.
86If CRYPTO_secure_malloc_init() is not called, this is equivalent to
87calling OPENSSL_clear_free().
88
89OPENSSL_secure_actual_size() tells the actual size allocated to the
90pointer; implementations may allocate more space than initially
91requested, in order to "round up" and reduce secure heap fragmentation.
92
93CRYPTO_secure_used() returns the number of bytes allocated in the
94secure heap.
95
96=head1 RETURN VALUES
97
98CRYPTO_secure_malloc_init() returns 0 on failure, 1 if successful,
99and 2 if successful but the heap could not be protected by memory
100mapping.
101
102CRYPTO_secure_malloc_initialized() returns 1 if the secure heap is
103available (that is, if CRYPTO_secure_malloc_init() has been called,
104but CRYPTO_secure_malloc_done() has not been called or failed) or 0 if not.
105
106OPENSSL_secure_malloc() and OPENSSL_secure_zalloc() return a pointer into
107the secure heap of the requested size, or C<NULL> if memory could not be
108allocated.
109
110CRYPTO_secure_allocated() returns 1 if the pointer is in the secure heap, or 0 if not.
111
112CRYPTO_secure_malloc_done() returns 1 if the secure memory area is released, or 0 if not.
113
114OPENSSL_secure_free() and OPENSSL_secure_clear_free() return no values.
115
116=head1 SEE ALSO
117
118L<OPENSSL_malloc(3)>,
119L<BN_new(3)>
120
121=head1 HISTORY
122
123OPENSSL_secure_clear_free() was added in OpenSSL 1.1.0g.
124
125=head1 COPYRIGHT
126
127Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
128
129Licensed under the OpenSSL license (the "License").  You may not use
130this file except in compliance with the License.  You can obtain a copy
131in the file LICENSE in the source distribution or at
132L<https://www.openssl.org/source/license.html>.
133
134=cut
135