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 */
34 typedef void * (* fips_dlopen_t)(const char * filename, int flag);
35 typedef void * (* fips_dlsym_t)(void *handle, const char *symbol);
37 static const char *wrapped_libs[] = {
42 static void *orig_handles[ARRAY_SIZE(wrapped_libs)];
44 /* Match 'filename' against an internal list of libraries for which
45 * libfips has wrappers.
47 * Returns true and sets *index_ret if a match is found.
48 * Returns false if no match is found. */
50 find_wrapped_library_index (const char *filename, unsigned *index_ret)
54 for (i = 0; i < ARRAY_SIZE(wrapped_libs); i++) {
55 if (strncmp(wrapped_libs[i], filename,
56 strlen (wrapped_libs[i])) == 0)
66 /* Many (most?) OpenGL programs dlopen libGL.so.1 rather than linking
67 * against it directly, which means they would not be seeing our
68 * wrapped GL symbols via LD_PRELOAD. So we catch the dlopen in a
69 * wrapper here and redirect it to our library.
72 dlopen (const char *filename, int flag)
78 /* Before deciding whether to redirect this dlopen to our own
79 * library, we call the real dlopen. This assures that any
80 * expected side-effects from loading the intended library are
81 * resolved. Below, we may still return a handle pointing to
82 * our own library, and not what is opened here. */
83 ret = dlwrap_real_dlopen (filename, flag);
85 /* If filename is not a wrapped library, just return real dlopen */
86 if (! find_wrapped_library_index (filename, &index))
89 assert (index < ARRAY_SIZE(orig_handles));
90 orig_handles[index] = ret;
92 /* Otherwise, we return our own handle so that we can intercept
93 * future calls to dlsym. We encode the index in the return value
94 * so that we can later map back to the originally requested
95 * dlopen-handle if necessary. */
97 return libfips_handle + index;
99 /* We find our own filename by looking up this very function
100 * (that is, this "dlopen"), with dladdr).*/
101 if (dladdr (dlopen, &info) == 0) {
102 fprintf (stderr, "Error: Failed to redirect dlopen of %s:\n",
107 libfips_handle = dlwrap_real_dlopen (info.dli_fname, flag);
109 return libfips_handle + index;
113 dlwrap_real_dlopen (const char *filename, int flag)
115 static fips_dlopen_t real_dlopen = NULL;
118 real_dlopen = (fips_dlopen_t) dlwrap_real_dlsym (RTLD_NEXT, "dlopen");
120 fprintf (stderr, "Error: Failed to find symbol for dlopen.\n");
125 return real_dlopen (filename, flag);
128 /* Since we redirect dlopens of libGL.so and libEGL.so to libfips we
129 * need to ensure that dlysm succeeds for all functions that might be
130 * defined in the real, underlying libGL library. But we're far too
131 * lazy to implement wrappers for function that would simply
132 * pass-through, so instead we also wrap dlysm and arrange for it to
133 * pass things through with RTLD_next if libfips does not have the
134 * function desired. */
136 dlsym (void *handle, const char *name)
141 /* All gl* and egl* symbols are preferentially looked up in libfips. */
142 if (STRNCMP_LITERAL (name, "gl") == 0 ||
143 STRNCMP_LITERAL (name, "egl") == 0)
145 symbol = dlwrap_real_dlsym (libfips_handle, name);
150 /* Failing that, anything specifically requested from the
151 * libfips library should be redirected to a real GL
154 /* We subtract the index back out of the handle (see the addition
155 * of the index in our wrapper for dlopen above) to then use the
156 * correct, original dlopen'ed handle for the library of
158 index = handle - libfips_handle;
159 if (index < ARRAY_SIZE(orig_handles)) {
160 return dlwrap_real_dlsym (orig_handles[index], name);
163 /* And anything else is some unrelated dlsym. Just pass it
164 * through. (This also covers the cases of lookups with
165 * special handles such as RTLD_DEFAULT or RTLD_NEXT.)
167 return dlwrap_real_dlsym (handle, name);
171 dlwrap_real_dlsym (void *handle, const char *name)
173 static fips_dlsym_t real_dlsym = NULL;
176 /* FIXME: This brute-force, hard-coded searching for a versioned
177 * symbol is really ugly. The only reason I'm doing this is because
178 * I need some way to lookup the "dlsym" function in libdl, but
179 * I can't use 'dlsym' to do it. So dlvsym works, but forces me
180 * to guess what the right version is.
182 * Potential fixes here:
184 * 1. Use libelf to actually inspect libdl.so and
185 * find the right version, (finding the right
186 * libdl.so can be made easier with
189 * 2. Use libelf to find the offset of the 'dlsym'
190 * symbol within libdl.so, (and then add this to
191 * the base address at which libdl.so is loaded
192 * as reported by dl_iterate_phdr).
194 * In the meantime, I'll just keep augmenting this
195 * hard-coded version list as people report bugs. */
196 const char *version[] = {
200 int num_versions = sizeof(version) / sizeof(version[0]);
202 for (i = 0; i < num_versions; i++) {
203 real_dlsym = (fips_dlsym_t) dlvsym (RTLD_NEXT, "dlsym",
208 if (i == num_versions) {
209 fprintf (stderr, "Internal error: Failed to find real dlsym\n");
211 "This may be a simple matter of fips not knowing about the version of GLIBC that\n"
212 "your program is using. Current known versions are:\n\n\t");
213 for (i = 0; i < num_versions; i++)
214 fprintf (stderr, "%s ", version[i]);
216 "\n\nYou can inspect your version by first finding libdl.so.2:\n"
218 "\tldd <your-program> | grep libdl.so\n"
220 "And then inspecting the version attached to the dlsym symbol:\n"
222 "\treadelf -s /path/to/libdl.so.2 | grep dlsym\n"
224 "And finally, adding the version to dlwrap.c:dlwrap_real_dlsym.\n");
230 return real_dlsym (handle, name);