xref: /freebsd/crypto/openssl/doc/man3/OPENSSL_malloc.pod (revision 95eb4b873b6a8b527c5bd78d7191975dfca38998) 
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().
103
104OPENSSL_cleanse() fills B<ptr> of size B<len> with a string of 0's.
105Use OPENSSL_cleanse() with care if the memory is a mapping of a file.
106If the storage controller uses write compression, then it's possible
107that sensitive tail bytes will survive zeroization because the block of
108zeros will be compressed. If the storage controller uses wear leveling,
109then the old sensitive data will not be overwritten; rather, a block of
1100's will be written at a new physical location.
111
112OPENSSL_strdup(), OPENSSL_strndup() and OPENSSL_memdup() are like the
113equivalent C functions, except that memory is allocated by calling the
114OPENSSL_malloc() and should be released by calling OPENSSL_free().
115
116OPENSSL_strlcpy(),
117OPENSSL_strlcat() and OPENSSL_strnlen() are equivalents of the common C
118library functions and are provided for portability.
119
120If no allocations have been done, it is possible to "swap out" the default
121implementations for OPENSSL_malloc(), OPENSSL_realloc() and OPENSSL_free()
122and replace them with alternate versions.
123CRYPTO_get_mem_functions() function fills in the given arguments with the
124function pointers for the current implementations.
125With CRYPTO_set_mem_functions(), you can specify a different set of functions.
126If any of B<malloc_fn>, B<realloc_fn>, or B<free_fn> are NULL, then
127the function is not changed.
128While it's permitted to swap out only a few and not all the functions
129with CRYPTO_set_mem_functions(), it's recommended to swap them all out
130at once.
131
132If the library is built with the C<crypto-mdebug> option, then one
133function, CRYPTO_get_alloc_counts(), and two additional environment
134variables, B<OPENSSL_MALLOC_FAILURES> and B<OPENSSL_MALLOC_FD>,
135are available.
136
137The function CRYPTO_get_alloc_counts() fills in the number of times
138each of CRYPTO_malloc(), CRYPTO_realloc(), and CRYPTO_free() have been
139called, into the values pointed to by B<mcount>, B<rcount>, and B<fcount>,
140respectively.  If a pointer is NULL, then the corresponding count is not stored.
141
142The variable
143B<OPENSSL_MALLOC_FAILURES> controls how often allocations should fail.
144It is a set of fields separated by semicolons, which each field is a count
145(defaulting to zero) and an optional atsign and percentage (defaulting
146to 100).  If the count is zero, then it lasts forever.  For example,
147C<100;@25> or C<100@0;0@25> means the first 100 allocations pass, then all
148other allocations (until the program exits or crashes) have a 25% chance of
149failing.
150
151If the variable B<OPENSSL_MALLOC_FD> is parsed as a positive integer, then
152it is taken as an open file descriptor. This is used in conjunction with
153B<OPENSSL_MALLOC_FAILURES> described above. For every allocation it will log
154details about how many allocations there have been so far, what percentage
155chance there is for this allocation failing, and whether it has actually failed.
156The following example in classic shell syntax shows how to use this (will not
157work on all platforms):
158
159  OPENSSL_MALLOC_FAILURES='200;@10'
160  export OPENSSL_MALLOC_FAILURES
161  OPENSSL_MALLOC_FD=3
162  export OPENSSL_MALLOC_FD
163  ...app invocation... 3>/tmp/log$$
164
165=head1 RETURN VALUES
166
167OPENSSL_malloc_init(), OPENSSL_free(), OPENSSL_clear_free()
168CRYPTO_free(), CRYPTO_clear_free() and CRYPTO_get_mem_functions()
169return no value.
170
171OPENSSL_malloc(), OPENSSL_zalloc(), OPENSSL_realloc(),
172OPENSSL_clear_realloc(),
173CRYPTO_malloc(), CRYPTO_zalloc(), CRYPTO_realloc(),
174CRYPTO_clear_realloc(),
175OPENSSL_strdup(), and OPENSSL_strndup()
176return a pointer to allocated memory or NULL on error.
177
178CRYPTO_set_mem_functions() returns 1 on success or 0 on failure (almost
179always because allocations have already happened).
180
181CRYPTO_mem_leaks(), CRYPTO_mem_leaks_fp(), CRYPTO_mem_leaks_cb(),
182CRYPTO_set_mem_debug(), and CRYPTO_mem_ctrl() are deprecated and are no-ops that
183always return -1.
184OPENSSL_mem_debug_push(), OPENSSL_mem_debug_pop(),
185CRYPTO_mem_debug_push(), and CRYPTO_mem_debug_pop()
186are deprecated and are no-ops that always return 0.
187
188=head1 HISTORY
189
190OPENSSL_mem_debug_push(), OPENSSL_mem_debug_pop(),
191CRYPTO_mem_debug_push(), CRYPTO_mem_debug_pop(),
192CRYPTO_mem_leaks(), CRYPTO_mem_leaks_fp(),
193CRYPTO_mem_leaks_cb(), CRYPTO_set_mem_debug(), CRYPTO_mem_ctrl()
194were deprecated in OpenSSL 3.0.
195The memory-leak checking has been deprecated in OpenSSL 3.0 in favor of
196clang's memory and leak sanitizer.
197
198
199=head1 COPYRIGHT
200
201Copyright 2016-2022 The OpenSSL Project Authors. All Rights Reserved.
202
203Licensed under the Apache License 2.0 (the "License").  You may not use
204this file except in compliance with the License.  You can obtain a copy
205in the file LICENSE in the source distribution or at
206L<https://www.openssl.org/source/license.html>.
207
208=cut
209