1 /* Copyright © 2013, Intel Corporation
3 * Permission is hereby granted, free of charge, to any person obtaining a copy
4 * of this software and associated documentation files (the "Software"), to deal
5 * in the Software without restriction, including without limitation the rights
6 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7 * copies of the Software, and to permit persons to whom the Software is
8 * furnished to do so, subject to the following conditions:
10 * The above copyright notice and this permission notice shall be included in
11 * all copies or substantial portions of the Software.
13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 /* dladdr is a glibc extension */
32 typedef void * (* fips_dlopen_t)(const char * filename, int flag);
33 typedef void * (* fips_dlsym_t)(void *handle, const char *symbol);
35 /* Many (most?) OpenGL programs dlopen libGL.so.1 rather than linking
36 * against it directly, which means they would not be seeing our
37 * wrapped GL symbols via LD_PRELOAD. So we catch the dlopen in a
38 * wrapper here and redirect it to our library.
41 dlopen (const char *filename, int flag)
46 /* Before deciding whether to redirect this dlopen to our own
47 * library, we call the real dlopen. This assures that any
48 * expected side-effects from loading the intended library are
49 * resolved. Below, we may still return a handle pointing to
50 * our own library, and not what is opened here. */
51 ret = dlwrap_real_dlopen (filename, flag);
53 /* Not libGL, so just return real dlopen */
54 if (STRNCMP_LITERAL (filename, "libGL.so"))
57 /* Otherwise, for all libGL lookups we redirectl dlopens to
58 * our own library. If we've resolved libfips_handle before,
59 * our work is done. */
61 return libfips_handle;
63 /* We find our own filename by looking up this very function
64 * (that is, this "dlopen"), with dladdr).*/
65 if (dladdr (dlopen, &info) == 0) {
66 fprintf (stderr, "Error: Failed to redirect dlopen of %s:\n",
71 libfips_handle = dlwrap_real_dlopen (info.dli_fname, flag);
73 return libfips_handle;
77 dlwrap_real_dlopen (const char *filename, int flag)
79 static fips_dlopen_t real_dlopen = NULL;
82 real_dlopen = (fips_dlopen_t) dlwrap_real_dlsym (RTLD_NEXT, "dlopen");
84 fprintf (stderr, "Error: Failed to find symbol for dlopen.\n");
89 return real_dlopen (filename, flag);
92 /* Since we redirect a dlopen of libGL.so to libfips we need to ensure
93 * that dlysm succeeds for all functions that might be defined in the
94 * real, underlying libGL library. But we're far too lazy to implement
95 * wrappers for function that would simply pass-through, so instead we
96 * also wrap dlysm and arrange for it to pass things through with
97 * RTLD_next if libfips does not have the function desired.
100 dlsym (void *handle, const char *name)
102 static void *libgl_handle = NULL;
105 /* All gl symbols are preferentially looked up in libfips. */
106 if (STRNCMP_LITERAL (name, "gl") == 0) {
107 symbol = dlwrap_real_dlsym (libfips_handle, name);
112 /* Failing that, anything specifically requested from the
113 * libfips library should be redirected to a real GL
115 if (handle == libfips_handle) {
117 libgl_handle = dlwrap_real_dlopen ("libGL.so.1", RTLD_LAZY);
118 return dlwrap_real_dlsym (libgl_handle, name);
121 /* And anything else is some unrelated dlsym. Just pass it through. */
122 return dlwrap_real_dlsym (handle, name);
126 dlwrap_real_dlsym (void *handle, const char *name)
128 static fips_dlsym_t real_dlsym = NULL;
131 /* FIXME: This brute-force, hard-coded searching for a versioned
132 * symbol is really ugly. The only reason I'm doing this is because
133 * I need some way to lookup the "dlsym" function in libdl, but
134 * I can't use 'dlsym' to do it. So dlvsym works, but forces me
135 * to guess what the right version is.
137 * Potential fixes here:
139 * 1. Use libelf to actually inspect libdl.so and
140 * find the right version, (finding the right
141 * libdl.so can be made easier with
144 * 2. Use libelf to find the offset of the 'dlsym'
145 * symbol within libdl.so, (and then add this to
146 * the base address at which libdl.so is loaded
147 * as reported by dl_iterate_phdr).
149 * In the meantime, I'll just keep augmenting this
150 * hard-coded version list as people report bugs. */
151 const char *version[] = {
155 int num_versions = sizeof(version) / sizeof(version[0]);
157 for (i = 0; i < num_versions; i++) {
158 real_dlsym = (fips_dlsym_t) dlvsym (RTLD_NEXT, "dlsym",
163 if (i == num_versions) {
164 fprintf (stderr, "Internal error: Failed to find real dlsym\n");
166 "This may be a simple matter of fips not knowing about the version of GLIBC that\n"
167 "your program is using. Current known versions are:\n\n\t");
168 for (i = 0; i < num_versions; i++)
169 fprintf (stderr, "%s ", version[i]);
171 "\n\nYou can inspect your version by first finding libdl.so.2:\n"
173 "\tldd <your-program> | grep libdl.so\n"
175 "And then inspecting the version attached to the dlsym symbol:\n"
177 "\treadelf -s /path/to/libdl.so.2 | grep dlsym\n"
179 "And finally, adding the version to dlwrap.c:dlwrap_real_dlsym.\n");
185 return real_dlsym (handle, name);