xref: /freebsd/crypto/openssl/doc/man3/OPENSSL_malloc.pod (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a) 
1=pod
2
3=head1 NAME
4
5OPENSSL_malloc_init,
6OPENSSL_malloc, OPENSSL_zalloc, OPENSSL_realloc, OPENSSL_free,
7OPENSSL_clear_realloc, OPENSSL_clear_free, OPENSSL_cleanse,
8CRYPTO_malloc, CRYPTO_zalloc, CRYPTO_realloc, CRYPTO_free,
9OPENSSL_strdup, OPENSSL_strndup,
10OPENSSL_memdup, OPENSSL_strlcpy, OPENSSL_strlcat,
11CRYPTO_strdup, CRYPTO_strndup,
12OPENSSL_mem_debug_push, OPENSSL_mem_debug_pop,
13CRYPTO_mem_debug_push, CRYPTO_mem_debug_pop,
14CRYPTO_clear_realloc, CRYPTO_clear_free,
15CRYPTO_malloc_fn, CRYPTO_realloc_fn, CRYPTO_free_fn,
16CRYPTO_get_mem_functions, CRYPTO_set_mem_functions,
17CRYPTO_get_alloc_counts,
18CRYPTO_set_mem_debug, CRYPTO_mem_ctrl,
19CRYPTO_mem_leaks, CRYPTO_mem_leaks_fp, CRYPTO_mem_leaks_cb,
20OPENSSL_MALLOC_FAILURES,
21OPENSSL_MALLOC_FD
22- Memory allocation functions
23
24=head1 SYNOPSIS
25
26 #include <openssl/crypto.h>
27
28 int OPENSSL_malloc_init(void);
29
30 void *OPENSSL_malloc(size_t num);
31 void *OPENSSL_zalloc(size_t num);
32 void *OPENSSL_realloc(void *addr, size_t num);
33 void OPENSSL_free(void *addr);
34 char *OPENSSL_strdup(const char *str);
35 char *OPENSSL_strndup(const char *str, size_t s);
36 size_t OPENSSL_strlcat(char *dst, const char *src, size_t size);
37 size_t OPENSSL_strlcpy(char *dst, const char *src, size_t size);
38 void *OPENSSL_memdup(void *data, size_t s);
39 void *OPENSSL_clear_realloc(void *p, size_t old_len, size_t num);
40 void OPENSSL_clear_free(void *str, size_t num);
41 void OPENSSL_cleanse(void *ptr, size_t len);
42
43 void *CRYPTO_malloc(size_t num, const char *file, int line);
44 void *CRYPTO_zalloc(size_t num, const char *file, int line);
45 void *CRYPTO_realloc(void *p, size_t num, const char *file, int line);
46 void CRYPTO_free(void *str, const char *, int);
47 char *CRYPTO_strdup(const char *p, const char *file, int line);
48 char *CRYPTO_strndup(const char *p, size_t num, const char *file, int line);
49 void *CRYPTO_clear_realloc(void *p, size_t old_len, size_t num,
50                            const char *file, int line);
51 void CRYPTO_clear_free(void *str, size_t num, const char *, int);
52
53 typedef void *(*CRYPTO_malloc_fn)(size_t num, const char *file, int line);
54 typedef void *(*CRYPTO_realloc_fn)(void *addr, size_t num, const char *file,
55                                    int line);
56 typedef void (*CRYPTO_free_fn)(void *addr, const char *file, int line);
57 void CRYPTO_get_mem_functions(CRYPTO_malloc_fn *malloc_fn,
58                               CRYPTO_realloc_fn *realloc_fn,
59                               CRYPTO_free_fn *free_fn);
60 int CRYPTO_set_mem_functions(CRYPTO_malloc_fn malloc_fn,
61                              CRYPTO_realloc_fn realloc_fn,
62                              CRYPTO_free_fn free_fn);
63
64 void CRYPTO_get_alloc_counts(int *mcount, int *rcount, int *fcount);
65
66 env OPENSSL_MALLOC_FAILURES=... <application>
67 env OPENSSL_MALLOC_FD=... <application>
68
69The following functions have been deprecated since OpenSSL 3.0, and can be
70hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
71see L<openssl_user_macros(7)>:
72
73 int CRYPTO_mem_leaks(BIO *b);
74 int CRYPTO_mem_leaks_fp(FILE *fp);
75 int CRYPTO_mem_leaks_cb(int (*cb)(const char *str, size_t len, void *u),
76                         void *u);
77
78 int CRYPTO_set_mem_debug(int onoff);
79 int CRYPTO_mem_ctrl(int mode);
80 int OPENSSL_mem_debug_push(const char *info);
81 int OPENSSL_mem_debug_pop(void);
82 int CRYPTO_mem_debug_push(const char *info, const char *file, int line);
83 int CRYPTO_mem_debug_pop(void);
84
85=head1 DESCRIPTION
86
87OpenSSL memory allocation is handled by the B<OPENSSL_xxx> API. These are
88generally macro's that add the standard C B<__FILE__> and B<__LINE__>
89parameters and call a lower-level B<CRYPTO_xxx> API.
90Some functions do not add those parameters, but exist for consistency.
91
92OPENSSL_malloc_init() does nothing and does not need to be called. It is
93included for compatibility with older versions of OpenSSL.
94
95OPENSSL_malloc(), OPENSSL_realloc(), and OPENSSL_free() are like the
96C malloc(), realloc(), and free() functions.
97OPENSSL_zalloc() calls memset() to zero the memory before returning.
98
99OPENSSL_clear_realloc() and OPENSSL_clear_free() should be used
100when the buffer at B<addr> holds sensitive information.
101The old buffer is filled with zero's by calling OPENSSL_cleanse()
102before ultimately calling OPENSSL_free(). If the argument to OPENSSL_free() is
103NULL, nothing is done.
104
105OPENSSL_cleanse() fills B<ptr> of size B<len> with a string of 0's.
106Use OPENSSL_cleanse() with care if the memory is a mapping of a file.
107If the storage controller uses write compression, then it's possible
108that sensitive tail bytes will survive zeroization because the block of
109zeros will be compressed. If the storage controller uses wear leveling,
110then the old sensitive data will not be overwritten; rather, a block of
1110's will be written at a new physical location.
112
113OPENSSL_strdup(), OPENSSL_strndup() and OPENSSL_memdup() are like the
114equivalent C functions, except that memory is allocated by calling the
115OPENSSL_malloc() and should be released by calling OPENSSL_free().
116
117OPENSSL_strlcpy(),
118OPENSSL_strlcat() and OPENSSL_strnlen() are equivalents of the common C
119library functions and are provided for portability.
120
121If no allocations have been done, it is possible to "swap out" the default
122implementations for OPENSSL_malloc(), OPENSSL_realloc() and OPENSSL_free()
123and replace them with alternate versions.
124CRYPTO_get_mem_functions() function fills in the given arguments with the
125function pointers for the current implementations.
126With CRYPTO_set_mem_functions(), you can specify a different set of functions.
127If any of B<malloc_fn>, B<realloc_fn>, or B<free_fn> are NULL, then
128the function is not changed.
129While it's permitted to swap out only a few and not all the functions
130with CRYPTO_set_mem_functions(), it's recommended to swap them all out
131at once.
132
133If the library is built with the C<crypto-mdebug> option, then one
134function, CRYPTO_get_alloc_counts(), and two additional environment
135variables, B<OPENSSL_MALLOC_FAILURES> and B<OPENSSL_MALLOC_FD>,
136are available.
137
138The function CRYPTO_get_alloc_counts() fills in the number of times
139each of CRYPTO_malloc(), CRYPTO_realloc(), and CRYPTO_free() have been
140called, into the values pointed to by B<mcount>, B<rcount>, and B<fcount>,
141respectively.  If a pointer is NULL, then the corresponding count is not stored.
142
143The variable
144B<OPENSSL_MALLOC_FAILURES> controls how often allocations should fail.
145It is a set of fields separated by semicolons, which each field is a count
146(defaulting to zero) and an optional atsign and percentage (defaulting
147to 100).  If the count is zero, then it lasts forever.  For example,
148C<100;@25> or C<100@0;0@25> means the first 100 allocations pass, then all
149other allocations (until the program exits or crashes) have a 25% chance of
150failing.
151
152If the variable B<OPENSSL_MALLOC_FD> is parsed as a positive integer, then
153it is taken as an open file descriptor. This is used in conjunction with
154B<OPENSSL_MALLOC_FAILURES> described above. For every allocation it will log
155details about how many allocations there have been so far, what percentage
156chance there is for this allocation failing, and whether it has actually failed.
157The following example in classic shell syntax shows how to use this (will not
158work on all platforms):
159
160  OPENSSL_MALLOC_FAILURES='200;@10'
161  export OPENSSL_MALLOC_FAILURES
162  OPENSSL_MALLOC_FD=3
163  export OPENSSL_MALLOC_FD
164  ...app invocation... 3>/tmp/log$$
165
166=head1 RETURN VALUES
167
168OPENSSL_malloc_init(), OPENSSL_free(), OPENSSL_clear_free()
169CRYPTO_free(), CRYPTO_clear_free() and CRYPTO_get_mem_functions()
170return no value.
171
172OPENSSL_malloc(), OPENSSL_zalloc(), OPENSSL_realloc(),
173OPENSSL_clear_realloc(),
174CRYPTO_malloc(), CRYPTO_zalloc(), CRYPTO_realloc(),
175CRYPTO_clear_realloc(),
176OPENSSL_strdup(), and OPENSSL_strndup()
177return a pointer to allocated memory or NULL on error.
178
179CRYPTO_set_mem_functions() returns 1 on success or 0 on failure (almost
180always because allocations have already happened).
181
182CRYPTO_mem_leaks(), CRYPTO_mem_leaks_fp(), CRYPTO_mem_leaks_cb(),
183CRYPTO_set_mem_debug(), and CRYPTO_mem_ctrl() are deprecated and are no-ops that
184always return -1.
185OPENSSL_mem_debug_push(), OPENSSL_mem_debug_pop(),
186CRYPTO_mem_debug_push(), and CRYPTO_mem_debug_pop()
187are deprecated and are no-ops that always return 0.
188
189=head1 HISTORY
190
191OPENSSL_mem_debug_push(), OPENSSL_mem_debug_pop(),
192CRYPTO_mem_debug_push(), CRYPTO_mem_debug_pop(),
193CRYPTO_mem_leaks(), CRYPTO_mem_leaks_fp(),
194CRYPTO_mem_leaks_cb(), CRYPTO_set_mem_debug(), CRYPTO_mem_ctrl()
195were deprecated in OpenSSL 3.0.
196The memory-leak checking has been deprecated in OpenSSL 3.0 in favor of
197clang's memory and leak sanitizer.
198
199
200=head1 COPYRIGHT
201
202Copyright 2016-2024 The OpenSSL Project Authors. All Rights Reserved.
203
204Licensed under the Apache License 2.0 (the "License").  You may not use
205this file except in compliance with the License.  You can obtain a copy
206in the file LICENSE in the source distribution or at
207L<https://www.openssl.org/source/license.html>.
208
209=cut
210