]>
Commit | Line | Data |
---|---|---|
c76147af | 1 | /* Post-processing of a symbol produced by dlsym, dlvsym. |
2b778ceb | 2 | Copyright (C) 1999-2021 Free Software Foundation, Inc. |
c76147af FW |
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 | |
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. | |
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 | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
17 | <https://www.gnu.org/licenses/>. */ | |
18 | ||
19 | ||
20 | /* Return the link map containing the caller address. */ | |
21 | static struct link_map * | |
22 | _dl_sym_find_caller_link_map (ElfW(Addr) caller) | |
23 | { | |
24 | struct link_map *l = _dl_find_dso_for_object (caller); | |
25 | if (l != NULL) | |
26 | return l; | |
27 | else | |
28 | /* If the address is not recognized the call comes from the main | |
29 | program (we hope). */ | |
30 | return GL(dl_ns)[LM_ID_BASE]._ns_loaded; | |
31 | } | |
32 | ||
33 | /* Translates RESULT, *REF, VALUE into a symbol address from the point | |
34 | of view of MATCH. Performs IFUNC resolution and auditing if | |
35 | necessary. If MATCH is NULL, CALLER is used to determine it. */ | |
36 | static void * | |
37 | _dl_sym_post (lookup_t result, const ElfW(Sym) *ref, void *value, | |
38 | ElfW(Addr) caller, struct link_map *match) | |
39 | { | |
40 | /* Resolve indirect function address. */ | |
41 | if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC)) | |
42 | { | |
43 | DL_FIXUP_VALUE_TYPE fixup | |
44 | = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value); | |
45 | fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup)); | |
46 | value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup); | |
47 | } | |
48 | ||
49 | #ifdef SHARED | |
50 | /* Auditing checkpoint: we have a new binding. Provide the | |
51 | auditing libraries the possibility to change the value and | |
52 | tell us whether further auditing is wanted. */ | |
53 | if (__glibc_unlikely (GLRO(dl_naudit) > 0)) | |
54 | { | |
55 | const char *strtab = (const char *) D_PTR (result, | |
56 | l_info[DT_STRTAB]); | |
57 | /* Compute index of the symbol entry in the symbol table of | |
58 | the DSO with the definition. */ | |
59 | unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result, | |
60 | l_info[DT_SYMTAB])); | |
61 | ||
62 | if (match == NULL) | |
63 | match = _dl_sym_find_caller_link_map (caller); | |
64 | ||
65 | if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0) | |
66 | { | |
67 | unsigned int altvalue = 0; | |
68 | struct audit_ifaces *afct = GLRO(dl_audit); | |
69 | /* Synthesize a symbol record where the st_value field is | |
70 | the result. */ | |
71 | ElfW(Sym) sym = *ref; | |
72 | sym.st_value = (ElfW(Addr)) value; | |
73 | ||
74 | for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) | |
75 | { | |
76 | struct auditstate *match_audit | |
77 | = link_map_audit_state (match, cnt); | |
78 | struct auditstate *result_audit | |
79 | = link_map_audit_state (result, cnt); | |
80 | if (afct->symbind != NULL | |
81 | && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0 | |
82 | || ((result_audit->bindflags & LA_FLG_BINDTO) | |
83 | != 0))) | |
84 | { | |
85 | unsigned int flags = altvalue | LA_SYMB_DLSYM; | |
86 | uintptr_t new_value | |
87 | = afct->symbind (&sym, ndx, | |
88 | &match_audit->cookie, | |
89 | &result_audit->cookie, | |
90 | &flags, strtab + ref->st_name); | |
91 | if (new_value != (uintptr_t) sym.st_value) | |
92 | { | |
93 | altvalue = LA_SYMB_ALTVALUE; | |
94 | sym.st_value = new_value; | |
95 | } | |
96 | } | |
97 | ||
98 | afct = afct->next; | |
99 | } | |
100 | ||
101 | value = (void *) sym.st_value; | |
102 | } | |
103 | } | |
104 | #endif | |
105 | return value; | |
106 | } |