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 */
36 typedef void * (* fips_dlopen_t)(const char * filename, int flag);
37 typedef void * (* fips_dlsym_t)(void *handle, const char *symbol);
39 static const char *wrapped_libs[] = {
45 static void *orig_handles[ARRAY_SIZE(wrapped_libs)];
47 /* Match 'filename' against an internal list of libraries for which
48 * libfips has wrappers.
50 * Returns true and sets *index_ret if a match is found.
51 * Returns false if no match is found. */
53 find_wrapped_library_index (const char *filename, unsigned *index_ret)
57 for (i = 0; i < ARRAY_SIZE(wrapped_libs); i++) {
58 if (strncmp(wrapped_libs[i], filename,
59 strlen (wrapped_libs[i])) == 0)
69 /* Perform a dlopen on the libfips library itself.
71 * Many places in fips need to lookup symbols within the libfips
72 * library itself, (and not in any other library). This function
73 * provides a reliable way to get a handle for performing such
76 * The returned handle can be passed to dlwrap_real_dlsym for the
79 dlwrap_dlopen_libfips (void)
83 /* We first find our own filename by looking up a function
84 * known to exist only in libfips. This function itself
85 * (dlwrap_dlopen_libfips) is a good one for that purpose. */
86 if (dladdr (dlwrap_dlopen_libfips, &info) == 0) {
87 fprintf (stderr, "Internal error: Failed to lookup filename of libfips library with dladdr\n");
91 return dlwrap_real_dlopen (info.dli_fname, RTLD_NOW);
94 /* Many (most?) OpenGL programs dlopen libGL.so.1 rather than linking
95 * against it directly, which means they would not be seeing our
96 * wrapped GL symbols via LD_PRELOAD. So we catch the dlopen in a
97 * wrapper here and redirect it to our library.
100 dlopen (const char *filename, int flag)
105 /* Before deciding whether to redirect this dlopen to our own
106 * library, we call the real dlopen. This assures that any
107 * expected side-effects from loading the intended library are
108 * resolved. Below, we may still return a handle pointing to
109 * our own library, and not what is opened here. */
110 ret = dlwrap_real_dlopen (filename, flag);
112 /* If filename is not a wrapped library, just return real dlopen */
113 if (! find_wrapped_library_index (filename, &index))
116 /* When the application dlopens any wrapped library starting
117 * with 'libGL', (whether libGL.so.1 or libGLESv2.so.2), let's
118 * continue to use that library handle for future lookups of
119 * OpenGL functions. */
120 if (STRNCMP_LITERAL (filename, "libGL") == 0)
121 glwrap_set_gl_handle (ret);
123 assert (index < ARRAY_SIZE(orig_handles));
124 orig_handles[index] = ret;
126 if (libfips_handle == NULL)
127 libfips_handle = dlwrap_dlopen_libfips ();
129 /* Otherwise, we return our own handle so that we can intercept
130 * future calls to dlsym. We encode the index in the return value
131 * so that we can later map back to the originally requested
132 * dlopen-handle if necessary. */
133 return libfips_handle + index;
137 dlwrap_real_dlopen (const char *filename, int flag)
139 static fips_dlopen_t real_dlopen = NULL;
142 real_dlopen = (fips_dlopen_t) dlwrap_real_dlsym (RTLD_NEXT, "dlopen");
144 fprintf (stderr, "Error: Failed to find symbol for dlopen.\n");
149 return real_dlopen (filename, flag);
152 /* Since we redirect dlopens of libGL.so and libEGL.so to libfips we
153 * need to ensure that dlysm succeeds for all functions that might be
154 * defined in the real, underlying libGL library. But we're far too
155 * lazy to implement wrappers for function that would simply
156 * pass-through, so instead we also wrap dlysm and arrange for it to
157 * pass things through with RTLD_next if libfips does not have the
158 * function desired. */
160 dlsym (void *handle, const char *name)
165 /* All gl* and egl* symbols are preferentially looked up in libfips. */
166 if (STRNCMP_LITERAL (name, "gl") == 0 ||
167 STRNCMP_LITERAL (name, "egl") == 0)
169 symbol = dlwrap_real_dlsym (libfips_handle, name);
174 /* Failing that, anything specifically requested from the
175 * libfips library should be redirected to a real GL
178 /* We subtract the index back out of the handle (see the addition
179 * of the index in our wrapper for dlopen above) to then use the
180 * correct, original dlopen'ed handle for the library of
182 index = handle - libfips_handle;
183 if (index < ARRAY_SIZE(orig_handles)) {
184 return dlwrap_real_dlsym (orig_handles[index], name);
187 /* And anything else is some unrelated dlsym. Just pass it
188 * through. (This also covers the cases of lookups with
189 * special handles such as RTLD_DEFAULT or RTLD_NEXT.)
191 return dlwrap_real_dlsym (handle, name);
195 dlwrap_real_dlsym (void *handle, const char *name)
197 static fips_dlsym_t real_dlsym = NULL;
200 /* FIXME: This brute-force, hard-coded searching for a versioned
201 * symbol is really ugly. The only reason I'm doing this is because
202 * I need some way to lookup the "dlsym" function in libdl, but
203 * I can't use 'dlsym' to do it. So dlvsym works, but forces me
204 * to guess what the right version is.
206 * Potential fixes here:
208 * 1. Use libelf to actually inspect libdl.so and
209 * find the right version, (finding the right
210 * libdl.so can be made easier with
213 * 2. Use libelf to find the offset of the 'dlsym'
214 * symbol within libdl.so, (and then add this to
215 * the base address at which libdl.so is loaded
216 * as reported by dl_iterate_phdr).
218 * In the meantime, I'll just keep augmenting this
219 * hard-coded version list as people report bugs. */
220 const char *version[] = {
224 int num_versions = sizeof(version) / sizeof(version[0]);
226 for (i = 0; i < num_versions; i++) {
227 real_dlsym = (fips_dlsym_t) dlvsym (RTLD_NEXT, "dlsym",
232 if (i == num_versions) {
233 fprintf (stderr, "Internal error: Failed to find real dlsym\n");
235 "This may be a simple matter of fips not knowing about the version of GLIBC that\n"
236 "your program is using. Current known versions are:\n\n\t");
237 for (i = 0; i < num_versions; i++)
238 fprintf (stderr, "%s ", version[i]);
240 "\n\nYou can inspect your version by first finding libdl.so.2:\n"
242 "\tldd <your-program> | grep libdl.so\n"
244 "And then inspecting the version attached to the dlsym symbol:\n"
246 "\treadelf -s /path/to/libdl.so.2 | grep dlsym\n"
248 "And finally, adding the version to dlwrap.c:dlwrap_real_dlsym.\n");
254 return real_dlsym (handle, name);