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94e365c6 | 1 | /* Look up a symbol in a shared object loaded by `dlopen'. |
04277e02 | 2 | Copyright (C) 1999-2019 Free Software Foundation, Inc. |
94e365c6 UD |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
94e365c6 UD |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
94e365c6 | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
94e365c6 | 18 | |
1100f849 | 19 | #include <assert.h> |
94e365c6 UD |
20 | #include <stddef.h> |
21 | #include <setjmp.h> | |
176790a7 | 22 | #include <stdlib.h> |
94e365c6 UD |
23 | #include <libintl.h> |
24 | ||
25 | #include <dlfcn.h> | |
26 | #include <ldsodefs.h> | |
27 | #include <dl-hash.h> | |
609cf614 | 28 | #include <sysdep-cancel.h> |
11bf311e | 29 | #include <dl-tls.h> |
42675c6f | 30 | #include <dl-irel.h> |
154d10bd UD |
31 | |
32 | ||
11bf311e | 33 | #ifdef SHARED |
154d10bd UD |
34 | /* Systems which do not have tls_index also probably have to define |
35 | DONT_USE_TLS_INDEX. */ | |
36 | ||
37 | # ifndef __TLS_GET_ADDR | |
38 | # define __TLS_GET_ADDR __tls_get_addr | |
39 | # endif | |
40 | ||
41 | /* Return the symbol address given the map of the module it is in and | |
42 | the symbol record. This is used in dl-sym.c. */ | |
43 | static void * | |
154d10bd UD |
44 | _dl_tls_symaddr (struct link_map *map, const ElfW(Sym) *ref) |
45 | { | |
46 | # ifndef DONT_USE_TLS_INDEX | |
47 | tls_index tmp = | |
48 | { | |
49 | .ti_module = map->l_tls_modid, | |
50 | .ti_offset = ref->st_value | |
51 | }; | |
52 | ||
53 | return __TLS_GET_ADDR (&tmp); | |
54 | # else | |
55 | return __TLS_GET_ADDR (map->l_tls_modid, ref->st_value); | |
56 | # endif | |
57 | } | |
58 | #endif | |
59 | ||
94e365c6 | 60 | |
1100f849 UD |
61 | struct call_dl_lookup_args |
62 | { | |
63 | /* Arguments to do_dlsym. */ | |
64 | struct link_map *map; | |
65 | const char *name; | |
1100f849 UD |
66 | struct r_found_version *vers; |
67 | int flags; | |
68 | ||
69 | /* Return values of do_dlsym. */ | |
70 | lookup_t loadbase; | |
71 | const ElfW(Sym) **refp; | |
72 | }; | |
73 | ||
74 | static void | |
75 | call_dl_lookup (void *ptr) | |
76 | { | |
77 | struct call_dl_lookup_args *args = (struct call_dl_lookup_args *) ptr; | |
78 | args->map = GLRO(dl_lookup_symbol_x) (args->name, args->map, args->refp, | |
c0a777e8 | 79 | args->map->l_scope, args->vers, 0, |
1100f849 UD |
80 | args->flags, NULL); |
81 | } | |
82 | ||
83 | ||
53761a8b | 84 | static void * |
f0323886 UD |
85 | do_sym (void *handle, const char *name, void *who, |
86 | struct r_found_version *vers, int flags) | |
94e365c6 | 87 | { |
94e365c6 | 88 | const ElfW(Sym) *ref = NULL; |
c0282c06 | 89 | lookup_t result; |
2b7238dd | 90 | ElfW(Addr) caller = (ElfW(Addr)) who; |
94e365c6 | 91 | |
be179c8a | 92 | struct link_map *l = _dl_find_dso_for_object (caller); |
f92338be UD |
93 | /* If the address is not recognized the call comes from the main |
94 | program (we hope). */ | |
be179c8a | 95 | struct link_map *match = l ? l : GL(dl_ns)[LM_ID_BASE]._ns_loaded; |
2b7238dd | 96 | |
94e365c6 | 97 | if (handle == RTLD_DEFAULT) |
1100f849 UD |
98 | { |
99 | /* Search the global scope. We have the simple case where | |
100 | we look up in the scope of an object which was part of | |
101 | the initial binary. And then the more complex part | |
102 | where the object is dynamically loaded and the scope | |
103 | array can change. */ | |
e4eb675d | 104 | if (RTLD_SINGLE_THREAD_P) |
1100f849 | 105 | result = GLRO(dl_lookup_symbol_x) (name, match, &ref, |
c0a777e8 | 106 | match->l_scope, vers, 0, |
1100f849 UD |
107 | flags | DL_LOOKUP_ADD_DEPENDENCY, |
108 | NULL); | |
109 | else | |
110 | { | |
1100f849 UD |
111 | struct call_dl_lookup_args args; |
112 | args.name = name; | |
113 | args.map = match; | |
1100f849 | 114 | args.vers = vers; |
b90395e6 UD |
115 | args.flags |
116 | = flags | DL_LOOKUP_ADD_DEPENDENCY | DL_LOOKUP_GSCOPE_LOCK; | |
1100f849 UD |
117 | args.refp = &ref; |
118 | ||
e4eb675d | 119 | THREAD_GSCOPE_SET_FLAG (); |
2449ae7b FW |
120 | struct dl_exception exception; |
121 | int err = _dl_catch_exception (&exception, call_dl_lookup, &args); | |
e4eb675d | 122 | THREAD_GSCOPE_RESET_FLAG (); |
2449ae7b FW |
123 | if (__glibc_unlikely (exception.errstring != NULL)) |
124 | _dl_signal_exception (err, &exception, NULL); | |
1100f849 UD |
125 | |
126 | result = args.map; | |
127 | } | |
128 | } | |
94e365c6 UD |
129 | else if (handle == RTLD_NEXT) |
130 | { | |
a1ffb40e | 131 | if (__glibc_unlikely (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded)) |
2373b30e | 132 | { |
173a06ec UD |
133 | if (match == NULL |
134 | || caller < match->l_map_start | |
135 | || caller >= match->l_map_end) | |
9e78f6f6 | 136 | _dl_signal_error (0, NULL, NULL, N_("\ |
94e365c6 | 137 | RTLD_NEXT used in code not dynamically loaded")); |
2373b30e | 138 | } |
94e365c6 | 139 | |
53761a8b | 140 | struct link_map *l = match; |
f92338be | 141 | while (l->l_loader != NULL) |
94e365c6 UD |
142 | l = l->l_loader; |
143 | ||
74c5693b | 144 | result = GLRO(dl_lookup_symbol_x) (name, match, &ref, l->l_local_scope, |
53761a8b | 145 | vers, 0, 0, match); |
94e365c6 UD |
146 | } |
147 | else | |
148 | { | |
149 | /* Search the scope of the given object. */ | |
150 | struct link_map *map = handle; | |
021723ab | 151 | result = GLRO(dl_lookup_symbol_x) (name, map, &ref, map->l_local_scope, |
53761a8b | 152 | vers, 0, flags, NULL); |
94e365c6 UD |
153 | } |
154 | ||
f92338be | 155 | if (ref != NULL) |
aed283dd | 156 | { |
9dcafc55 UD |
157 | void *value; |
158 | ||
11bf311e | 159 | #ifdef SHARED |
aed283dd UD |
160 | if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS) |
161 | /* The found symbol is a thread-local storage variable. | |
162 | Return the address for to the current thread. */ | |
9dcafc55 UD |
163 | value = _dl_tls_symaddr (result, ref); |
164 | else | |
165 | #endif | |
166 | value = DL_SYMBOL_ADDRESS (result, ref); | |
167 | ||
bc5e8462 | 168 | /* Resolve indirect function address. */ |
a1ffb40e | 169 | if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC)) |
8608ae1f L |
170 | { |
171 | DL_FIXUP_VALUE_TYPE fixup | |
172 | = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value); | |
42675c6f | 173 | fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup)); |
8608ae1f L |
174 | value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup); |
175 | } | |
bc5e8462 | 176 | |
9dcafc55 UD |
177 | #ifdef SHARED |
178 | /* Auditing checkpoint: we have a new binding. Provide the | |
179 | auditing libraries the possibility to change the value and | |
180 | tell us whether further auditing is wanted. */ | |
a1ffb40e | 181 | if (__glibc_unlikely (GLRO(dl_naudit) > 0)) |
9dcafc55 UD |
182 | { |
183 | const char *strtab = (const char *) D_PTR (result, | |
184 | l_info[DT_STRTAB]); | |
185 | /* Compute index of the symbol entry in the symbol table of | |
186 | the DSO with the definition. */ | |
187 | unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result, | |
188 | l_info[DT_SYMTAB])); | |
189 | ||
190 | if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0) | |
191 | { | |
192 | unsigned int altvalue = 0; | |
193 | struct audit_ifaces *afct = GLRO(dl_audit); | |
194 | /* Synthesize a symbol record where the st_value field is | |
195 | the result. */ | |
196 | ElfW(Sym) sym = *ref; | |
197 | sym.st_value = (ElfW(Addr)) value; | |
198 | ||
199 | for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) | |
200 | { | |
201 | if (afct->symbind != NULL | |
202 | && ((match->l_audit[cnt].bindflags & LA_FLG_BINDFROM) | |
203 | != 0 | |
204 | || ((result->l_audit[cnt].bindflags & LA_FLG_BINDTO) | |
205 | != 0))) | |
206 | { | |
207 | unsigned int flags = altvalue | LA_SYMB_DLSYM; | |
208 | uintptr_t new_value | |
209 | = afct->symbind (&sym, ndx, | |
210 | &match->l_audit[cnt].cookie, | |
211 | &result->l_audit[cnt].cookie, | |
212 | &flags, strtab + ref->st_name); | |
213 | if (new_value != (uintptr_t) sym.st_value) | |
214 | { | |
215 | altvalue = LA_SYMB_ALTVALUE; | |
216 | sym.st_value = new_value; | |
217 | } | |
218 | } | |
219 | ||
220 | afct = afct->next; | |
221 | } | |
222 | ||
223 | value = (void *) sym.st_value; | |
224 | } | |
225 | } | |
aed283dd UD |
226 | #endif |
227 | ||
9dcafc55 | 228 | return value; |
aed283dd | 229 | } |
5e76a346 | 230 | |
94e365c6 UD |
231 | return NULL; |
232 | } | |
53761a8b UD |
233 | |
234 | ||
53761a8b | 235 | void * |
53761a8b UD |
236 | _dl_vsym (void *handle, const char *name, const char *version, void *who) |
237 | { | |
238 | struct r_found_version vers; | |
239 | ||
240 | /* Compute hash value to the version string. */ | |
241 | vers.name = version; | |
242 | vers.hidden = 1; | |
243 | vers.hash = _dl_elf_hash (version); | |
244 | /* We don't have a specific file where the symbol can be found. */ | |
245 | vers.filename = NULL; | |
246 | ||
f0323886 | 247 | return do_sym (handle, name, who, &vers, 0); |
53761a8b UD |
248 | } |
249 | ||
250 | ||
251 | void * | |
53761a8b UD |
252 | _dl_sym (void *handle, const char *name, void *who) |
253 | { | |
f0323886 | 254 | return do_sym (handle, name, who, NULL, DL_LOOKUP_RETURN_NEWEST); |
53761a8b | 255 | } |