1/*
2 * Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#ifndef OSSL_INTERNAL_DSO_H
11# define OSSL_INTERNAL_DSO_H
12# pragma once
13
14# include <openssl/crypto.h>
15# include "internal/dsoerr.h"
16
17/* These values are used as commands to DSO_ctrl() */
18# define DSO_CTRL_GET_FLAGS      1
19# define DSO_CTRL_SET_FLAGS      2
20# define DSO_CTRL_OR_FLAGS       3
21
22/*
23 * By default, DSO_load() will translate the provided filename into a form
24 * typical for the platform using the dso_name_converter function of the
25 * method. Eg. win32 will transform "blah" into "blah.dll", and dlfcn will
26 * transform it into "libblah.so". This callback could even utilise the
27 * DSO_METHOD's converter too if it only wants to override behaviour for
28 * one or two possible DSO methods. However, the following flag can be
29 * set in a DSO to prevent *any* native name-translation at all - eg. if
30 * the caller has prompted the user for a path to a driver library so the
31 * filename should be interpreted as-is.
32 */
33# define DSO_FLAG_NO_NAME_TRANSLATION            0x01
34/*
35 * An extra flag to give if only the extension should be added as
36 * translation.  This is obviously only of importance on Unix and other
37 * operating systems where the translation also may prefix the name with
38 * something, like 'lib', and ignored everywhere else. This flag is also
39 * ignored if DSO_FLAG_NO_NAME_TRANSLATION is used at the same time.
40 */
41# define DSO_FLAG_NAME_TRANSLATION_EXT_ONLY      0x02
42
43/*
44 * Don't unload the DSO when we call DSO_free()
45 */
46# define DSO_FLAG_NO_UNLOAD_ON_FREE              0x04
47
48/*
49 * This flag loads the library with public symbols. Meaning: The exported
50 * symbols of this library are public to all libraries loaded after this
51 * library. At the moment only implemented in unix.
52 */
53# define DSO_FLAG_GLOBAL_SYMBOLS                 0x20
54
55typedef void (*DSO_FUNC_TYPE) (void);
56
57typedef struct dso_st DSO;
58typedef struct dso_meth_st DSO_METHOD;
59
60/*
61 * The function prototype used for method functions (or caller-provided
62 * callbacks) that transform filenames. They are passed a DSO structure
63 * pointer (or NULL if they are to be used independently of a DSO object) and
64 * a filename to transform. They should either return NULL (if there is an
65 * error condition) or a newly allocated string containing the transformed
66 * form that the caller will need to free with OPENSSL_free() when done.
67 */
68typedef char *(*DSO_NAME_CONVERTER_FUNC)(DSO *, const char *);
69/*
70 * The function prototype used for method functions (or caller-provided
71 * callbacks) that merge two file specifications. They are passed a DSO
72 * structure pointer (or NULL if they are to be used independently of a DSO
73 * object) and two file specifications to merge. They should either return
74 * NULL (if there is an error condition) or a newly allocated string
75 * containing the result of merging that the caller will need to free with
76 * OPENSSL_free() when done. Here, merging means that bits and pieces are
77 * taken from each of the file specifications and added together in whatever
78 * fashion that is sensible for the DSO method in question.  The only rule
79 * that really applies is that if the two specification contain pieces of the
80 * same type, the copy from the first string takes priority.  One could see
81 * it as the first specification is the one given by the user and the second
82 * being a bunch of defaults to add on if they're missing in the first.
83 */
84typedef char *(*DSO_MERGER_FUNC)(DSO *, const char *, const char *);
85
86DSO *DSO_new(void);
87int DSO_free(DSO *dso);
88int DSO_flags(DSO *dso);
89int DSO_up_ref(DSO *dso);
90long DSO_ctrl(DSO *dso, int cmd, long larg, void *parg);
91
92/*
93 * These functions can be used to get/set the platform-independent filename
94 * used for a DSO. NB: set will fail if the DSO is already loaded.
95 */
96const char *DSO_get_filename(DSO *dso);
97int DSO_set_filename(DSO *dso, const char *filename);
98/*
99 * This function will invoke the DSO's name_converter callback to translate a
100 * filename, or if the callback isn't set it will instead use the DSO_METHOD's
101 * converter. If "filename" is NULL, the "filename" in the DSO itself will be
102 * used. If the DSO_FLAG_NO_NAME_TRANSLATION flag is set, then the filename is
103 * simply duplicated. NB: This function is usually called from within a
104 * DSO_METHOD during the processing of a DSO_load() call, and is exposed so
105 * that caller-created DSO_METHODs can do the same thing. A non-NULL return
106 * value will need to be OPENSSL_free()'d.
107 */
108char *DSO_convert_filename(DSO *dso, const char *filename);
109/*
110 * This function will invoke the DSO's merger callback to merge two file
111 * specifications, or if the callback isn't set it will instead use the
112 * DSO_METHOD's merger.  A non-NULL return value will need to be
113 * OPENSSL_free()'d.
114 */
115char *DSO_merge(DSO *dso, const char *filespec1, const char *filespec2);
116
117/*
118 * The all-singing all-dancing load function, you normally pass NULL for the
119 * first and third parameters. Use DSO_up_ref and DSO_free for subsequent
120 * reference count handling. Any flags passed in will be set in the
121 * constructed DSO after its init() function but before the load operation.
122 * If 'dso' is non-NULL, 'flags' is ignored.
123 */
124DSO *DSO_load(DSO *dso, const char *filename, DSO_METHOD *meth, int flags);
125
126/* This function binds to a function inside a shared library. */
127DSO_FUNC_TYPE DSO_bind_func(DSO *dso, const char *symname);
128
129/*
130 * This method is the default, but will beg, borrow, or steal whatever method
131 * should be the default on any particular platform (including
132 * DSO_METH_null() if necessary).
133 */
134DSO_METHOD *DSO_METHOD_openssl(void);
135
136/*
137 * This function writes null-terminated pathname of DSO module containing
138 * 'addr' into 'sz' large caller-provided 'path' and returns the number of
139 * characters [including trailing zero] written to it. If 'sz' is 0 or
140 * negative, 'path' is ignored and required amount of characters [including
141 * trailing zero] to accommodate pathname is returned. If 'addr' is NULL, then
142 * pathname of cryptolib itself is returned. Negative or zero return value
143 * denotes error.
144 */
145int DSO_pathbyaddr(void *addr, char *path, int sz);
146
147/*
148 * Like DSO_pathbyaddr() but instead returns a handle to the DSO for the symbol
149 * or NULL on error.
150 */
151DSO *DSO_dsobyaddr(void *addr, int flags);
152
153/*
154 * This function should be used with caution! It looks up symbols in *all*
155 * loaded modules and if module gets unloaded by somebody else attempt to
156 * dereference the pointer is doomed to have fatal consequences. Primary
157 * usage for this function is to probe *core* system functionality, e.g.
158 * check if getnameinfo(3) is available at run-time without bothering about
159 * OS-specific details such as libc.so.versioning or where does it actually
160 * reside: in libc itself or libsocket.
161 */
162void *DSO_global_lookup(const char *name);
163
164#endif
165