xref: /openssl/include/internal/dso.h (revision a28d06f3)
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 
55 typedef void (*DSO_FUNC_TYPE) (void);
56 
57 typedef struct dso_st DSO;
58 typedef 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  */
68 typedef 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  */
84 typedef char *(*DSO_MERGER_FUNC)(DSO *, const char *, const char *);
85 
86 DSO *DSO_new(void);
87 int DSO_free(DSO *dso);
88 int DSO_flags(DSO *dso);
89 int DSO_up_ref(DSO *dso);
90 long 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  */
96 const char *DSO_get_filename(DSO *dso);
97 int 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  */
108 char *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  */
115 char *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  */
124 DSO *DSO_load(DSO *dso, const char *filename, DSO_METHOD *meth, int flags);
125 
126 /* This function binds to a function inside a shared library. */
127 DSO_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  */
134 DSO_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  */
145 int 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  */
151 DSO *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  */
162 void *DSO_global_lookup(const char *name);
163 
164 #endif
165