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f753fa7d | 1 | /* Support for GNU properties. x86 version. |
04277e02 | 2 | Copyright (C) 2018-2019 Free Software Foundation, Inc. |
f753fa7d L |
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 | |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
f753fa7d L |
18 | |
19 | #ifndef _DL_PROP_H | |
20 | #define _DL_PROP_H | |
21 | ||
22 | #include <not-cancel.h> | |
23 | ||
24 | extern void _dl_cet_check (struct link_map *, const char *) | |
25 | attribute_hidden; | |
26 | extern void _dl_cet_open_check (struct link_map *) | |
27 | attribute_hidden; | |
28 | ||
29 | static inline void __attribute__ ((always_inline)) | |
30 | _rtld_main_check (struct link_map *m, const char *program) | |
31 | { | |
32 | #if CET_ENABLED | |
33 | _dl_cet_check (m, program); | |
34 | #endif | |
35 | } | |
36 | ||
37 | static inline void __attribute__ ((always_inline)) | |
38 | _dl_open_check (struct link_map *m) | |
39 | { | |
40 | #if CET_ENABLED | |
41 | _dl_cet_open_check (m); | |
42 | #endif | |
43 | } | |
44 | ||
45 | static inline void __attribute__ ((unused)) | |
46 | _dl_process_cet_property_note (struct link_map *l, | |
47 | const ElfW(Nhdr) *note, | |
48 | const ElfW(Addr) size, | |
49 | const ElfW(Addr) align) | |
50 | { | |
51 | #if CET_ENABLED | |
d524fa6c L |
52 | /* Skip if we have seen a NT_GNU_PROPERTY_TYPE_0 note before. */ |
53 | if (l->l_cet != lc_unknown) | |
54 | return; | |
55 | ||
f753fa7d L |
56 | /* The NT_GNU_PROPERTY_TYPE_0 note must be aliged to 4 bytes in |
57 | 32-bit objects and to 8 bytes in 64-bit objects. Skip notes | |
58 | with incorrect alignment. */ | |
59 | if (align != (__ELF_NATIVE_CLASS / 8)) | |
60 | return; | |
61 | ||
62 | const ElfW(Addr) start = (ElfW(Addr)) note; | |
63 | ||
d524fa6c L |
64 | unsigned int feature_1 = 0; |
65 | unsigned int last_type = 0; | |
66 | ||
f753fa7d L |
67 | while ((ElfW(Addr)) (note + 1) - start < size) |
68 | { | |
69 | /* Find the NT_GNU_PROPERTY_TYPE_0 note. */ | |
70 | if (note->n_namesz == 4 | |
71 | && note->n_type == NT_GNU_PROPERTY_TYPE_0 | |
72 | && memcmp (note + 1, "GNU", 4) == 0) | |
73 | { | |
d524fa6c L |
74 | /* Stop if we see more than one GNU property note which may |
75 | be generated by the older linker. */ | |
76 | if (l->l_cet != lc_unknown) | |
77 | return; | |
78 | ||
79 | /* Check CET status now. */ | |
80 | l->l_cet = lc_none; | |
81 | ||
f753fa7d L |
82 | /* Check for invalid property. */ |
83 | if (note->n_descsz < 8 | |
84 | || (note->n_descsz % sizeof (ElfW(Addr))) != 0) | |
d524fa6c | 85 | return; |
f753fa7d L |
86 | |
87 | /* Start and end of property array. */ | |
88 | unsigned char *ptr = (unsigned char *) (note + 1) + 4; | |
89 | unsigned char *ptr_end = ptr + note->n_descsz; | |
90 | ||
98864ed0 | 91 | do |
f753fa7d L |
92 | { |
93 | unsigned int type = *(unsigned int *) ptr; | |
94 | unsigned int datasz = *(unsigned int *) (ptr + 4); | |
95 | ||
d524fa6c L |
96 | /* Property type must be in ascending order. */ |
97 | if (type < last_type) | |
98 | return; | |
99 | ||
f753fa7d L |
100 | ptr += 8; |
101 | if ((ptr + datasz) > ptr_end) | |
d524fa6c L |
102 | return; |
103 | ||
104 | last_type = type; | |
f753fa7d | 105 | |
98864ed0 | 106 | if (type == GNU_PROPERTY_X86_FEATURE_1_AND) |
f753fa7d | 107 | { |
98864ed0 L |
108 | /* The size of GNU_PROPERTY_X86_FEATURE_1_AND is 4 |
109 | bytes. When seeing GNU_PROPERTY_X86_FEATURE_1_AND, | |
110 | we stop the search regardless if its size is correct | |
111 | or not. There is no point to continue if this note | |
112 | is ill-formed. */ | |
d524fa6c L |
113 | if (datasz != 4) |
114 | return; | |
115 | ||
116 | feature_1 = *(unsigned int *) ptr; | |
117 | ||
118 | /* Keep searching for the next GNU property note | |
119 | generated by the older linker. */ | |
120 | break; | |
121 | } | |
122 | else if (type > GNU_PROPERTY_X86_FEATURE_1_AND) | |
123 | { | |
124 | /* Stop since property type is in ascending order. */ | |
98864ed0 | 125 | return; |
f753fa7d | 126 | } |
98864ed0 L |
127 | |
128 | /* Check the next property item. */ | |
129 | ptr += ALIGN_UP (datasz, sizeof (ElfW(Addr))); | |
f753fa7d | 130 | } |
98864ed0 | 131 | while ((ptr_end - ptr) >= 8); |
f753fa7d L |
132 | } |
133 | ||
134 | /* NB: Note sections like .note.ABI-tag and .note.gnu.build-id are | |
135 | aligned to 4 bytes in 64-bit ELF objects. */ | |
136 | note = ((const void *) note | |
137 | + ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz, | |
138 | align)); | |
139 | } | |
d524fa6c L |
140 | |
141 | /* We get here only if there is one or no GNU property note. */ | |
142 | if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_IBT)) | |
143 | l->l_cet |= lc_ibt; | |
144 | if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_SHSTK)) | |
145 | l->l_cet |= lc_shstk; | |
f753fa7d L |
146 | #endif |
147 | } | |
148 | ||
149 | #ifdef FILEBUF_SIZE | |
150 | static inline int __attribute__ ((unused)) | |
151 | _dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph, | |
152 | int fd, struct filebuf *fbp) | |
153 | { | |
154 | # if CET_ENABLED | |
155 | const ElfW(Nhdr) *note; | |
156 | ElfW(Nhdr) *note_malloced = NULL; | |
157 | ElfW(Addr) size = ph->p_filesz; | |
158 | ||
159 | if (ph->p_offset + size <= (size_t) fbp->len) | |
160 | note = (const void *) (fbp->buf + ph->p_offset); | |
161 | else | |
162 | { | |
163 | if (size < __MAX_ALLOCA_CUTOFF) | |
164 | note = alloca (size); | |
165 | else | |
166 | { | |
167 | note_malloced = malloc (size); | |
168 | note = note_malloced; | |
169 | } | |
170 | __lseek (fd, ph->p_offset, SEEK_SET); | |
171 | if (__read_nocancel (fd, (void *) note, size) != size) | |
172 | { | |
173 | if (note_malloced) | |
174 | free (note_malloced); | |
175 | return -1; | |
176 | } | |
177 | } | |
178 | ||
179 | _dl_process_cet_property_note (l, note, size, ph->p_align); | |
180 | if (note_malloced) | |
181 | free (note_malloced); | |
182 | # endif | |
183 | return 0; | |
184 | } | |
185 | #endif | |
186 | ||
187 | static inline int __attribute__ ((unused)) | |
188 | _rtld_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph) | |
189 | { | |
190 | const ElfW(Nhdr) *note = (const void *) (ph->p_vaddr + l->l_addr); | |
191 | _dl_process_cet_property_note (l, note, ph->p_memsz, ph->p_align); | |
192 | return 0; | |
193 | } | |
194 | ||
195 | #endif /* _DL_PROP_H */ |