mirror of
https://github.com/openssl/openssl.git
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5071824321
Reviewed-by: Emilia Käsper <emilia@openssl.org> (Merged from https://github.com/openssl/openssl/pull/2228)
238 lines
9.8 KiB
Plaintext
238 lines
9.8 KiB
Plaintext
=pod
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=head1 NAME
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OPENSSL_malloc_init,
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OPENSSL_malloc, OPENSSL_zalloc, OPENSSL_realloc, OPENSSL_free,
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OPENSSL_clear_realloc, OPENSSL_clear_free, OPENSSL_cleanse,
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CRYPTO_malloc, CRYPTO_zalloc, CRYPTO_realloc, CRYPTO_free,
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OPENSSL_strdup, OPENSSL_strndup,
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OPENSSL_memdup, OPENSSL_strlcpy, OPENSSL_strlcat,
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OPENSSL_hexstr2buf, OPENSSL_buf2hexstr, OPENSSL_hexchar2int,
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CRYPTO_strdup, CRYPTO_strndup,
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OPENSSL_mem_debug_push, OPENSSL_mem_debug_pop,
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CRYPTO_mem_debug_push, CRYPTO_mem_debug_pop,
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CRYPTO_clear_realloc, CRYPTO_clear_free,
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CRYPTO_get_mem_functions, CRYPTO_set_mem_functions,
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CRYPTO_set_mem_debug, CRYPTO_mem_ctrl,
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CRYPTO_mem_leaks, CRYPTO_mem_leaks_fp
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OPENSSL_MALLOC_FAILURES,
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OPENSSL_MALLOC_FD
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- Memory allocation functions
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=head1 SYNOPSIS
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#include <openssl/crypto.h>
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int OPENSSL_malloc_init(void)
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void *OPENSSL_malloc(size_t num)
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void *OPENSSL_zalloc(size_t num)
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void *OPENSSL_realloc(void *addr, size_t num)
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void OPENSSL_free(void *addr)
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char *OPENSSL_strdup(const char *str)
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char *OPENSSL_strndup(const char *str, size_t s)
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size_t OPENSSL_strlcat(char *dst, const char *src, size_t size);
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size_t OPENSSL_strlcpy(char *dst, const char *src, size_t size);
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void *OPENSSL_memdup(void *data, size_t s)
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void *OPENSSL_clear_realloc(void *p, size_t old_len, size_t num)
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void OPENSSL_clear_free(void *str, size_t num)
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void OPENSSL_cleanse(void *ptr, size_t len);
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unsigned char *OPENSSL_hexstr2buf(const char *str, long *len);
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char *OPENSSL_buf2hexstr(const unsigned char *buffer, long len);
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int OPENSSL_hexchar2int(unsigned char c);
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void *CRYPTO_malloc(size_t num, const char *file, int line)
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void *CRYPTO_zalloc(size_t num, const char *file, int line)
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void *CRYPTO_realloc(void *p, size_t num, const char *file, int line)
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void CRYPTO_free(void *str, const char *, int)
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char *CRYPTO_strdup(const char *p, const char *file, int line)
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char *CRYPTO_strndup(const char *p, size_t num, const char *file, int line)
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void *CRYPTO_clear_realloc(void *p, size_t old_len, size_t num, const char *file, int line)
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void CRYPTO_clear_free(void *str, size_t num, const char *, int)
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void CRYPTO_get_mem_functions(
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void *(**m)(size_t, const char *, int),
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void *(**r)(void *, size_t, const char *, int),
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void (**f)(void *, const char *, int))
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int CRYPTO_set_mem_functions(
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void *(*m)(size_t, const char *, int),
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void *(*r)(void *, size_t, const char *, int),
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void (*f)(void *, const char *, int))
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int CRYPTO_set_mem_debug(int onoff)
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env OPENSSL_MALLOC_FAILURES=... <application>
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env OPENSSL_MALLOC_FD=... <application>
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int CRYPTO_mem_ctrl(int mode);
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int OPENSSL_mem_debug_push(const char *info)
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int OPENSSL_mem_debug_pop(void);
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int CRYPTO_mem_debug_push(const char *info, const char *file, int line);
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int CRYPTO_mem_debug_pop(void);
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void CRYPTO_mem_leaks(BIO *b);
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void CRYPTO_mem_leaks_fp(FILE *fp);
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=head1 DESCRIPTION
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OpenSSL memory allocation is handled by the B<OPENSSL_xxx> API. These are
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generally macro's that add the standard C B<__FILE__> and B<__LINE__>
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parameters and call a lower-level B<CRYPTO_xxx> API.
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Some functions do not add those parameters, but exist for consistency.
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OPENSSL_malloc_init() sets the lower-level memory allocation functions
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to their default implementation.
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It is generally not necessary to call this, except perhaps in certain
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shared-library situations.
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OPENSSL_malloc(), OPENSSL_realloc(), and OPENSSL_free() are like the
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C malloc(), realloc(), and free() functions.
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OPENSSL_zalloc() calls memset() to zero the memory before returning.
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OPENSSL_clear_realloc() and OPENSSL_clear_free() should be used
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when the buffer at B<addr> holds sensitive information.
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The old buffer is filled with zero's by calling OPENSSL_cleanse()
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before ultimately calling OPENSSL_free().
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OPENSSL_cleanse() fills B<ptr> of size B<len> with a string of 0's.
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Use OPENSSL_cleanse() with care if the memory is a mapping of a file.
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If the storage controller uses write compression, then its possible
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that sensitive tail bytes will survive zeroization because the block of
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zeros will be compressed. If the storage controller uses wear leveling,
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then the old sensitive data will not be overwritten; rather, a block of
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0's will be written at a new physical location.
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OPENSSL_strdup(), OPENSSL_strndup() and OPENSSL_memdup() are like the
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equivalent C functions, except that memory is allocated by calling the
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OPENSSL_malloc() and should be released by calling OPENSSL_free().
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OPENSSL_strlcpy(),
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OPENSSL_strlcat() and OPENSSL_strnlen() are equivalents of the common C
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library functions and are provided for portability.
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OPENSSL_hexstr2buf() parses B<str> as a hex string and returns a
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pointer to the parsed value. The memory is allocated by calling
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OPENSSL_malloc() and should be released by calling OPENSSL_free().
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If B<len> is not NULL, it is filled in with the output length.
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Colons between two-character hex "bytes" are ignored.
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An odd number of hex digits is an error.
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OPENSSL_buf2hexstr() takes the specified buffer and length, and returns
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a hex string for value, or NULL on error.
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B<Buffer> cannot be NULL; if B<len> is 0 an empty string is returned.
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OPENSSL_hexchar2int() converts a character to the hexadecimal equivalent,
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or returns -1 on error.
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If no allocations have been done, it is possible to "swap out" the default
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implementations for OPENSSL_malloc(), OPENSSL_realloc and OPENSSL_free()
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and replace them with alternate versions (hooks).
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CRYPTO_get_mem_functions() function fills in the given arguments with the
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function pointers for the current implementations.
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With CRYPTO_set_mem_functions(), you can specify a different set of functions.
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If any of B<m>, B<r>, or B<f> are NULL, then the function is not changed.
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The default implementation can include some debugging capability (if enabled
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at build-time).
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This adds some overhead by keeping a list of all memory allocations, and
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removes items from the list when they are free'd.
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This is most useful for identifying memory leaks.
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CRYPTO_set_mem_debug() turns this tracking on and off. In order to have
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any effect, is must be called before any of the allocation functions
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(e.g., CRYPTO_malloc()) are called, and is therefore normally one of the
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first lines of main() in an application.
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If the library is built with the C<crypto-mdebug> option, then two additional
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environment variables can be used for testing failure handling. The variable
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B<OPENSSL_MALLOC_FAILURES> controls how often allocations should fail.
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It is a set of fields separated by semicolons, which each field is a count
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(defaulting to zero) and an optional atsign and percentage (defaulting
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to 100). If the count is zero, then it lasts forever. For example,
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C<100;@25> or C<100@0;0@25> means the first 100 allocations pass, then all
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other allocations (until the program exits or crashes) have a 25% chance of
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failing.
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If the variable B<OPENSSL_MALLOC_FD> is parsed as a positive integer, then
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it is taken as an open file descriptor, and a record of all allocations is
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written to that descriptor. If an allocation will fail, and the platform
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supports it, then a backtrace will be written to the descriptor. This can
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be useful because a malloc may fail but not be checked, and problems will
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only occur later. The following example in classic shell syntax shows how
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to use this (will not work on all platforms):
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OPENSSL_MALLOC_FAILURES='200;@10'
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export OPENSSL_MALLOC_FAILURES
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OPENSSL_MALLOC_FD=3
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export OPENSSL_MALLOC_FD
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...app invocation... 3>/tmp/log$$
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CRYPTO_mem_ctrl() provides fine-grained control of memory leak tracking.
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To enable tracking call CRYPTO_mem_ctrl() with a B<mode> argument of
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the B<CRYPTO_MEM_CHECK_ON>.
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To disable tracking call CRYPTO_mem_ctrl() with a B<mode> argument of
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the B<CRYPTO_MEM_CHECK_OFF>.
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While checking memory, it can be useful to store additional context
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about what is being done.
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For example, identifying the field names when parsing a complicated
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data structure.
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OPENSSL_mem_debug_push() (which calls CRYPTO_mem_debug_push())
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attachs an identifying string to the allocation stack.
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This must be a global or other static string; it is not copied.
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OPENSSL_mem_debug_pop() removes identifying state from the stack.
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At the end of the program, calling CRYPTO_mem_leaks() or
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CRYPTO_mem_leaks_fp() will report all "leaked" memory, writing it
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to the specified BIO B<b> or FILE B<fp>. These functions return 1 if
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there are no leaks, 0 if there are leaks and -1 if an error occurred.
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=head1 RETURN VALUES
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OPENSSL_malloc_init(), OPENSSL_free(), OPENSSL_clear_free()
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CRYPTO_free(), CRYPTO_clear_free() and CRYPTO_get_mem_functions()
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return no value.
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CRYPTO_mem_leaks() and CRYPTO_mem_leaks_fp() return 1 if there
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are no leaks, 0 if there are leaks and -1 if an error occurred.
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OPENSSL_malloc(), OPENSSL_zalloc(), OPENSSL_realloc(),
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OPENSSL_clear_realloc(),
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CRYPTO_malloc(), CRYPTO_zalloc(), CRYPTO_realloc(),
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CRYPTO_clear_realloc(),
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OPENSSL_buf2hexstr(), OPENSSL_hexstr2buf(),
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OPENSSL_strdup(), and OPENSSL_strndup()
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return a pointer to allocated memory or NULL on error.
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CRYPTO_set_mem_functions() and CRYPTO_set_mem_debug()
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return 1 on success or 0 on failure (almost
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always because allocations have already happened).
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CRYPTO_mem_ctrl() returns -1 if an error occurred, otherwise the
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previous value of the mode.
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OPENSSL_mem_debug_push() and OPENSSL_mem_debug_pop()
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return 1 on success or 0 on failure.
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=head1 NOTES
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While it's permitted to swap out only a few and not all the functions
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with CRYPTO_set_mem_functions(), it's recommended to swap them all out
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at once. I<This applies specially if OpenSSL was built with the
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configuration option> C<crypto-mdebug> I<enabled. In case, swapping out
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only, say, the malloc() implementation is outright dangerous.>
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=head1 COPYRIGHT
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Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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