1 /* Read the dynamic section at DYN and fill in INFO with indices DT_*.
2 Copyright (C) 2012-2023 Free Software Foundation, Inc.
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 /* Populate dynamic tags in l_info. */
20
21 #ifndef _GET_DYNAMIC_INFO_H
22 #define _GET_DYNAMIC_INFO_H
23
24 #include <assert.h>
25 #include <dl-machine-rel.h>
26 #include <libc-diag.h>
27
28 static inline void __attribute__ ((unused, always_inline))
29 elf_get_dynamic_info (struct link_map *l, bool bootstrap,
30 bool static_pie_bootstrap)
31 {
32 #if __ELF_NATIVE_CLASS == 32
33 typedef Elf32_Word d_tag_utype;
34 #elif __ELF_NATIVE_CLASS == 64
35 typedef Elf64_Xword d_tag_utype;
36 #endif
37
38 #ifndef STATIC_PIE_BOOTSTRAP
39 if (!bootstrap && l->l_ld == NULL)
40 return;
41 #endif
42
43 ElfW(Dyn) **info = l->l_info;
44
45 for (ElfW(Dyn) *dyn = l->l_ld; dyn->d_tag != DT_NULL; dyn++)
46 {
47 d_tag_utype i;
48
49 if ((d_tag_utype) dyn->d_tag < DT_NUM)
50 i = dyn->d_tag;
51 else if (dyn->d_tag >= DT_LOPROC
52 && dyn->d_tag < DT_LOPROC + DT_THISPROCNUM)
53 i = dyn->d_tag - DT_LOPROC + DT_NUM;
54 else if ((d_tag_utype) DT_VERSIONTAGIDX (dyn->d_tag) < DT_VERSIONTAGNUM)
55 i = VERSYMIDX (dyn->d_tag);
56 else if ((d_tag_utype) DT_EXTRATAGIDX (dyn->d_tag) < DT_EXTRANUM)
57 i = DT_EXTRATAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
58 + DT_VERSIONTAGNUM;
59 else if ((d_tag_utype) DT_VALTAGIDX (dyn->d_tag) < DT_VALNUM)
60 i = DT_VALTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
61 + DT_VERSIONTAGNUM + DT_EXTRANUM;
62 else if ((d_tag_utype) DT_ADDRTAGIDX (dyn->d_tag) < DT_ADDRNUM)
63 i = DT_ADDRTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
64 + DT_VERSIONTAGNUM + DT_EXTRANUM + DT_VALNUM;
65 else
66 continue;
67
68 info[i] = dyn;
69 }
70
71 /* Don't adjust .dynamic unnecessarily. */
72 if (l->l_addr != 0 && dl_relocate_ld (l))
73 {
74 ElfW(Addr) l_addr = l->l_addr;
75
76 # define ADJUST_DYN_INFO(tag) \
77 do \
78 { \
79 if (info[tag] != NULL) \
80 info[tag]->d_un.d_ptr += l_addr; \
81 } \
82 while (0)
83
84 ADJUST_DYN_INFO (DT_HASH);
85 ADJUST_DYN_INFO (DT_PLTGOT);
86 ADJUST_DYN_INFO (DT_STRTAB);
87 ADJUST_DYN_INFO (DT_SYMTAB);
88 ADJUST_DYN_INFO (DT_RELR);
89 ADJUST_DYN_INFO (DT_JMPREL);
90 ADJUST_DYN_INFO (VERSYMIDX (DT_VERSYM));
91 ADJUST_DYN_INFO (ADDRIDX (DT_GNU_HASH));
92 # undef ADJUST_DYN_INFO
93
94 /* DT_RELA/DT_REL are mandatory. But they may have zero value if
95 there is DT_RELR. Don't relocate them if they are zero. */
96 # define ADJUST_DYN_INFO(tag) \
97 do \
98 if (info[tag] != NULL && info[tag]->d_un.d_ptr != 0) \
99 info[tag]->d_un.d_ptr += l_addr; \
100 while (0)
101
102 # if ! ELF_MACHINE_NO_RELA
103 ADJUST_DYN_INFO (DT_RELA);
104 # endif
105 # if ! ELF_MACHINE_NO_REL
106 ADJUST_DYN_INFO (DT_REL);
107 # endif
108 # undef ADJUST_DYN_INFO
109 }
110 if (info[DT_PLTREL] != NULL)
111 {
112 #if ELF_MACHINE_NO_RELA
113 assert (info[DT_PLTREL]->d_un.d_val == DT_REL);
114 #elif ELF_MACHINE_NO_REL
115 assert (info[DT_PLTREL]->d_un.d_val == DT_RELA);
116 #else
117 assert (info[DT_PLTREL]->d_un.d_val == DT_REL
118 || info[DT_PLTREL]->d_un.d_val == DT_RELA);
119 #endif
120 }
121 #if ! ELF_MACHINE_NO_RELA
122 if (info[DT_RELA] != NULL)
123 assert (info[DT_RELAENT]->d_un.d_val == sizeof (ElfW(Rela)));
124 # endif
125 # if ! ELF_MACHINE_NO_REL
126 if (info[DT_REL] != NULL)
127 assert (info[DT_RELENT]->d_un.d_val == sizeof (ElfW(Rel)));
128 #endif
129 if (info[DT_RELR] != NULL)
130 assert (info[DT_RELRENT]->d_un.d_val == sizeof (ElfW(Relr)));
131 if (bootstrap || static_pie_bootstrap)
132 {
133 assert (info[DT_RUNPATH] == NULL);
134 assert (info[DT_RPATH] == NULL);
135 }
136 if (bootstrap)
137 {
138 /* Only the bind now flags are allowed. */
139 assert (info[VERSYMIDX (DT_FLAGS_1)] == NULL
140 || (info[VERSYMIDX (DT_FLAGS_1)]->d_un.d_val & ~DF_1_NOW) == 0);
141 /* Flags must not be set for ld.so. */
142 assert (info[DT_FLAGS] == NULL
143 || (info[DT_FLAGS]->d_un.d_val & ~DF_BIND_NOW) == 0);
144 }
145 else
146 {
147 if (info[DT_FLAGS] != NULL)
148 {
149 /* Flags are used. Translate to the old form where available.
150 Since these l_info entries are only tested for NULL pointers it
151 is ok if they point to the DT_FLAGS entry. */
152 l->l_flags = info[DT_FLAGS]->d_un.d_val;
153
154 if (l->l_flags & DF_SYMBOLIC)
155 info[DT_SYMBOLIC] = info[DT_FLAGS];
156 if (l->l_flags & DF_TEXTREL)
157 info[DT_TEXTREL] = info[DT_FLAGS];
158 if (l->l_flags & DF_BIND_NOW)
159 info[DT_BIND_NOW] = info[DT_FLAGS];
160 }
161
162 if (info[VERSYMIDX (DT_FLAGS_1)] != NULL)
163 {
164 l->l_flags_1 = info[VERSYMIDX (DT_FLAGS_1)]->d_un.d_val;
165 if (l->l_flags_1 & DF_1_NODELETE)
166 l->l_nodelete_pending = true;
167
168 /* Only DT_1_SUPPORTED_MASK bits are supported, and we would like
169 to assert this, but we can't. Users have been setting
170 unsupported DF_1_* flags for a long time and glibc has ignored
171 them. Therefore to avoid breaking existing applications the
172 best we can do is add a warning during debugging with the
173 intent of notifying the user of the problem. */
174 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0)
175 && l->l_flags_1 & ~DT_1_SUPPORTED_MASK)
176 _dl_debug_printf ("\nWARNING: Unsupported flag value(s) of 0x%x "
177 "in DT_FLAGS_1.\n",
178 l->l_flags_1 & ~DT_1_SUPPORTED_MASK);
179
180 if (l->l_flags_1 & DF_1_NOW)
181 info[DT_BIND_NOW] = info[VERSYMIDX (DT_FLAGS_1)];
182 }
183
184 if (info[DT_RUNPATH] != NULL)
185 /* If both RUNPATH and RPATH are given, the latter is ignored. */
186 info[DT_RPATH] = NULL;
187 }
188 }
189
190 #endif