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_allocated, 11CRYPTO_secure_used - secure heap storage 12 13=head1 SYNOPSIS 14 15 #include <openssl/crypto.h> 16 17 int CRYPTO_secure_malloc_init(size_t size, size_t minsize); 18 19 int CRYPTO_secure_malloc_initialized(); 20 21 int CRYPTO_secure_malloc_done(); 22 23 void *OPENSSL_secure_malloc(size_t num); 24 void *CRYPTO_secure_malloc(size_t num, const char *file, int line); 25 26 void *OPENSSL_secure_zalloc(size_t num); 27 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line); 28 29 void OPENSSL_secure_free(void* ptr); 30 void CRYPTO_secure_free(void *ptr, const char *, int); 31 32 void OPENSSL_secure_clear_free(void* ptr, size_t num); 33 void CRYPTO_secure_clear_free(void *ptr, size_t num, const char *, int); 34 35 size_t OPENSSL_secure_actual_size(const void *ptr); 36 37 int CRYPTO_secure_allocated(const void *ptr); 38 size_t CRYPTO_secure_used(); 39 40=head1 DESCRIPTION 41 42In order to help protect applications (particularly long-running servers) 43from pointer overruns or underruns that could return arbitrary data from 44the program's dynamic memory area, where keys and other sensitive 45information might be stored, OpenSSL supports the concept of a "secure heap." 46The level and type of security guarantees depend on the operating system. 47It is a good idea to review the code and see if it addresses your 48threat model and concerns. 49 50If a secure heap is used, then private key B<BIGNUM> values are stored there. 51This protects long-term storage of private keys, but will not necessarily 52put all intermediate values and computations there. 53 54CRYPTO_secure_malloc_init() creates the secure heap, with the specified 55C<size> in bytes. The C<minsize> parameter is the minimum size to 56allocate from the heap or zero to use a reasonable default value. 57Both C<size> and, if specified, C<minsize> must be a power of two and 58C<minsize> should generally be small, for example 16 or 32. 59C<minsize> must be less than a quarter of C<size> in any case. 60 61CRYPTO_secure_malloc_initialized() indicates whether or not the secure 62heap as been initialized and is available. 63 64CRYPTO_secure_malloc_done() releases the heap and makes the memory unavailable 65to the process if all secure memory has been freed. 66It can take noticeably long to complete. 67 68OPENSSL_secure_malloc() allocates C<num> bytes from the heap. 69If CRYPTO_secure_malloc_init() is not called, this is equivalent to 70calling OPENSSL_malloc(). 71It is a macro that expands to 72CRYPTO_secure_malloc() and adds the C<__FILE__> and C<__LINE__> parameters. 73 74OPENSSL_secure_zalloc() and CRYPTO_secure_zalloc() are like 75OPENSSL_secure_malloc() and CRYPTO_secure_malloc(), respectively, 76except that they call memset() to zero the memory before returning. 77 78OPENSSL_secure_free() releases the memory at C<ptr> back to the heap. 79It must be called with a value previously obtained from 80OPENSSL_secure_malloc(). 81If CRYPTO_secure_malloc_init() is not called, this is equivalent to 82calling OPENSSL_free(). 83It exists for consistency with OPENSSL_secure_malloc() , and 84is a macro that expands to CRYPTO_secure_free() and adds the C<__FILE__> 85and C<__LINE__> parameters.. If the argument to OPENSSL_secure_free() 86is NULL, nothing is done. 87 88OPENSSL_secure_clear_free() is similar to OPENSSL_secure_free() except 89that it has an additional C<num> parameter which is used to clear 90the memory if it was not allocated from the secure heap. 91If CRYPTO_secure_malloc_init() is not called, this is equivalent to 92calling OPENSSL_clear_free(). If the argument to OPENSSL_secure_clear_free() 93is NULL, nothing is done. 94 95OPENSSL_secure_actual_size() tells the actual size allocated to the 96pointer; implementations may allocate more space than initially 97requested, in order to "round up" and reduce secure heap fragmentation. 98 99OPENSSL_secure_allocated() tells if a pointer is allocated in the secure heap. 100 101CRYPTO_secure_used() returns the number of bytes allocated in the 102secure heap. 103 104=head1 RETURN VALUES 105 106CRYPTO_secure_malloc_init() returns 0 on failure, 1 if successful, 107and 2 if successful but the heap could not be protected by memory 108mapping. 109 110CRYPTO_secure_malloc_initialized() returns 1 if the secure heap is 111available (that is, if CRYPTO_secure_malloc_init() has been called, 112but CRYPTO_secure_malloc_done() has not been called or failed) or 0 if not. 113 114OPENSSL_secure_malloc() and OPENSSL_secure_zalloc() return a pointer into 115the secure heap of the requested size, or C<NULL> if memory could not be 116allocated. 117 118CRYPTO_secure_allocated() returns 1 if the pointer is in the secure heap, or 0 if not. 119 120CRYPTO_secure_malloc_done() returns 1 if the secure memory area is released, or 0 if not. 121 122OPENSSL_secure_free() and OPENSSL_secure_clear_free() return no values. 123 124=head1 SEE ALSO 125 126L<OPENSSL_malloc(3)>, 127L<BN_new(3)> 128 129=head1 HISTORY 130 131The OPENSSL_secure_clear_free() function was added in OpenSSL 1.1.0g. 132 133The second argument to CRYPTO_secure_malloc_init() was changed from an B<int> to 134a B<size_t> in OpenSSL 3.0. 135 136=head1 COPYRIGHT 137 138Copyright 2015-2024 The OpenSSL Project Authors. All Rights Reserved. 139 140Licensed under the Apache License 2.0 (the "License"). You may not use 141this file except in compliance with the License. You can obtain a copy 142in the file LICENSE in the source distribution or at 143L<https://www.openssl.org/source/license.html>. 144 145=cut 146