mirror of
https://github.com/openssl/openssl.git
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92 lines
3.0 KiB
Plaintext
92 lines
3.0 KiB
Plaintext
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=pod
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=head1 NAME
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CRYPTO_secure_malloc_init, CRYPTO_secure_malloc_done, OPENSSL_secure_malloc, OPENSSL_secure_free, OPENSSL_secure_allocated - use secure heap storage
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=head1 SYNOPSIS
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#include <openssl/crypto.h>
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int CRYPTO_secure_malloc_init(size_t size, int minsize);
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int CRYPTO_secure_malloc_initialized();
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void CRYPTO_secure_malloc_done();
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void *OPENSSL_secure_malloc(int num);
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void OPENSSL_secure_free(void* ptr);
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int OPENSSL_secure_allocated(const void* ptr);
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=head1 DESCRIPTION
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In order to help protect applications (particularly long-running servers)
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from pointer overruns or underruns that could return arbitrary data from
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the program's dynamic memory area, where keys and other sensitive
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information might be stored, OpenSSL supports the concept of a "secure heap."
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The level and type of security guarantees depend on the operating system.
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It is a good idea to review the code and see if it addresses your
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threat model and concerns.
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If a secure heap is used, then private key B<BIGNUM> values are stored there.
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This protects long-term storage of private keys, but will not necessarily
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put all intermediate values and computations there.
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B<CRYPTO_secure_malloc_init> creates the secure heap, with the specified
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C<size> in bytes. The C<minsize> parameter is the minimum size to
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allocate from the heap. Both C<size> and C<minsize> must be a power
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of two. It is an error to call this after any B<OPENSSL_secure_malloc>
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calls have been made.
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B<CRYPTO_secure_malloc_initialized> indicates whether or not the secure
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heap as been initialized and is available.
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B<CRYPTO_secure_malloc_done> releases the heap and makes the memory unavailable
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to the process. It can take noticeably long to complete.
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B<OPENSSL_secure_malloc> allocates C<num> bytes from the heap.
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If B<CRYPTO_secure_malloc_init> is not called, this is equivalent to
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calling B<OPENSSL_malloc>.
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B<OPENSSL_secure_free> releases the memory at C<ptr> back to the heap.
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It must be called with a value previously obtained from
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B<OPENSSL_secure_malloc>.
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If B<CRYPTO_secure_malloc_init> is not called, this is equivalent to
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calling B<OPENSSL_free>.
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B<OPENSSL_secure_allocated> tells whether or not a pointer is within
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the secure heap.
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=head1 RETURN VALUES
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B<CRYPTO_secure_malloc_init> returns 0 on failure, 1 if successful,
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and 2 if successful but the heap could not be protected by memory
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mapping.
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B<CRYPTO_secure_malloc_initialized> returns 1 if the secure heap is
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available (that is, if B<CRYPTO_secure_malloc_init> has been called,
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but B<CRYPTO_secure_malloc_done> has not) or 0 if not.
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B<OPENSSL_secure_malloc> returns a pointer into the secure heap of
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the requested size, or C<NULL> if memory could not be allocated.
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B<CRYPTO_secure_allocated> returns 1 if the pointer is in the
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the secure heap, or 0 if not.
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B<CRYPTO_secure_malloc_done> and B<OPENSSL_secure_free>
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return no values.
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=head1 SEE ALSO
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L<BN_new(3)|BN_new(3)>,
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L<bn_internal(3)|bn_internal(3)>
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=head1 HISTORY
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These functions were contributed to the OpenSSL project by
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Akamai Technologies in April, 2014.
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=cut
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