1/* Support for GNU properties. x86 version.
2 Copyright (C) 2018-2021 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#ifndef _DL_PROP_H
20#define _DL_PROP_H
21
22#include <libintl.h>
23
24extern void _dl_cet_check (struct link_map *, const char *)
25 attribute_hidden;
26extern void _dl_cet_open_check (struct link_map *)
27 attribute_hidden;
28
29static void
30dl_isa_level_check (struct link_map *m, const char *program)
31{
32 const struct cpu_features *cpu_features = __get_cpu_features ();
33 unsigned int i;
34 struct link_map *l;
35
36 i = m->l_searchlist.r_nlist;
37 while (i-- > 0)
38 {
39 /* Check each shared object to see if ISA level is compatible. */
40 l = m->l_initfini[i];
41
42 /* Skip ISA level check if functions have been executed. */
43 if (l->l_init_called)
44 continue;
45
46#ifdef SHARED
47 /* Skip ISA level check for ld.so since ld.so won't run if its ISA
48 level is higher than CPU. */
49 if (l == &GL(dl_rtld_map) || l->l_real == &GL(dl_rtld_map))
50 continue;
51#endif
52
53 if ((l->l_x86_isa_1_needed & cpu_features->isa_1)
54 != l->l_x86_isa_1_needed)
55 {
56 if (program)
57 _dl_fatal_printf ("%s: CPU ISA level is lower than required\n",
58 *l->l_name != '\0' ? l->l_name : program);
59 else
60 _dl_signal_error (0, l->l_name, "dlopen",
61 N_("CPU ISA level is lower than required"));
62 }
63 }
64}
65
66static inline void __attribute__ ((always_inline))
67_rtld_main_check (struct link_map *m, const char *program)
68{
69 dl_isa_level_check (m, program);
70#if CET_ENABLED
71 _dl_cet_check (m, program);
72#endif
73}
74
75static inline void __attribute__ ((always_inline))
76_dl_open_check (struct link_map *m)
77{
78 dl_isa_level_check (m, NULL);
79#if CET_ENABLED
80 _dl_cet_open_check (m);
81#endif
82}
83
84static inline void __attribute__ ((unused))
85_dl_process_property_note (struct link_map *l, const ElfW(Nhdr) *note,
86 const ElfW(Addr) size, const ElfW(Addr) align)
87{
88 /* Skip if we have seen a NT_GNU_PROPERTY_TYPE_0 note before. */
89 if (l->l_property != lc_property_unknown)
90 return;
91
92 /* The NT_GNU_PROPERTY_TYPE_0 note must be aliged to 4 bytes in
93 32-bit objects and to 8 bytes in 64-bit objects. Skip notes
94 with incorrect alignment. */
95 if (align != (__ELF_NATIVE_CLASS / 8))
96 return;
97
98 const ElfW(Addr) start = (ElfW(Addr)) note;
99
100 unsigned int feature_1_and = 0;
101 unsigned int isa_1_needed = 0;
102 unsigned int last_type = 0;
103
104 while ((ElfW(Addr)) (note + 1) - start < size)
105 {
106 /* Find the NT_GNU_PROPERTY_TYPE_0 note. */
107 if (note->n_namesz == 4
108 && note->n_type == NT_GNU_PROPERTY_TYPE_0
109 && memcmp (note + 1, "GNU", 4) == 0)
110 {
111 /* Stop if we see more than one GNU property note which may
112 be generated by the older linker. */
113 if (l->l_property != lc_property_unknown)
114 return;
115
116 /* Check CET status and ISA levels now. */
117 l->l_property = lc_property_none;
118
119 /* Check for invalid property. */
120 if (note->n_descsz < 8
121 || (note->n_descsz % sizeof (ElfW(Addr))) != 0)
122 return;
123
124 /* Start and end of property array. */
125 unsigned char *ptr = (unsigned char *) (note + 1) + 4;
126 unsigned char *ptr_end = ptr + note->n_descsz;
127
128 do
129 {
130 unsigned int type = *(unsigned int *) ptr;
131 unsigned int datasz = *(unsigned int *) (ptr + 4);
132
133 /* Property type must be in ascending order. */
134 if (type < last_type)
135 return;
136
137 ptr += 8;
138 if ((ptr + datasz) > ptr_end)
139 return;
140
141 last_type = type;
142
143 if (type == GNU_PROPERTY_X86_FEATURE_1_AND
144 || type == GNU_PROPERTY_X86_ISA_1_NEEDED)
145 {
146 /* The sizes of types which we are searching for are
147 4 bytes. There is no point to continue if this
148 note is ill-formed. */
149 if (datasz != 4)
150 return;
151
152 /* NB: Stop the scan only after seeing all types which
153 we are searching for. */
154 _Static_assert ((GNU_PROPERTY_X86_ISA_1_NEEDED >
155 GNU_PROPERTY_X86_FEATURE_1_AND),
156 "GNU_PROPERTY_X86_ISA_1_NEEDED > "
157 "GNU_PROPERTY_X86_FEATURE_1_AND");
158 if (type == GNU_PROPERTY_X86_FEATURE_1_AND)
159 feature_1_and = *(unsigned int *) ptr;
160 else
161 {
162 isa_1_needed = *(unsigned int *) ptr;
163
164 /* Keep searching for the next GNU property note
165 generated by the older linker. */
166 break;
167 }
168 }
169 else if (type > GNU_PROPERTY_X86_ISA_1_NEEDED)
170 {
171 /* Stop the scan since property type is in ascending
172 order. */
173 break;
174 }
175
176 /* Check the next property item. */
177 ptr += ALIGN_UP (datasz, sizeof (ElfW(Addr)));
178 }
179 while ((ptr_end - ptr) >= 8);
180 }
181
182 /* NB: Note sections like .note.ABI-tag and .note.gnu.build-id are
183 aligned to 4 bytes in 64-bit ELF objects. */
184 note = ((const void *) note
185 + ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz,
186 align));
187 }
188
189 /* We get here only if there is one or no GNU property note. */
190 if (isa_1_needed != 0 || feature_1_and != 0)
191 {
192 l->l_property = lc_property_valid;
193 l->l_x86_isa_1_needed = isa_1_needed;
194 l->l_x86_feature_1_and = feature_1_and;
195 }
196 else
197 l->l_property = lc_property_none;
198}
199
200static inline void __attribute__ ((unused))
201_dl_process_pt_note (struct link_map *l, int fd, const ElfW(Phdr) *ph)
202{
203 const ElfW(Nhdr) *note = (const void *) (ph->p_vaddr + l->l_addr);
204 _dl_process_property_note (l, note, ph->p_memsz, ph->p_align);
205}
206
207static inline int __attribute__ ((always_inline))
208_dl_process_gnu_property (struct link_map *l, int fd, uint32_t type,
209 uint32_t datasz, void *data)
210{
211 return 0;
212}
213
214#endif /* _DL_PROP_H */
215