1 /*
2 * Copyright © 2016 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24 #ifdef HAVE_DL_ITERATE_PHDR
25 #include <dlfcn.h>
26 #include <link.h>
27 #include <stddef.h>
28 #include <string.h>
29
30 #include "build_id.h"
31 #include "macros.h"
32
33 #ifndef NT_GNU_BUILD_ID
34 #define NT_GNU_BUILD_ID 3
35 #endif
36
37 #ifndef ElfW
38 #define ElfW(type) Elf_##type
39 #endif
40
41 struct build_id_note {
42 ElfW(Nhdr) nhdr;
43
44 char name[4]; /* Note name for build-id is "GNU\0" */
45 uint8_t build_id[0];
46 };
47
48 struct callback_data {
49 /* Base address of shared object, taken from Dl_info::dli_fbase */
50 const void *dli_fbase;
51
52 struct build_id_note *note;
53 };
54
55 static int
build_id_find_nhdr_callback(struct dl_phdr_info * info,size_t size,void * data_)56 build_id_find_nhdr_callback(struct dl_phdr_info *info, size_t size, void *data_)
57 {
58 struct callback_data *data = data_;
59
60 /* Calculate address where shared object is mapped into the process space.
61 * (Using the base address and the virtual address of the first LOAD segment)
62 */
63 void *map_start = NULL;
64 for (unsigned i = 0; i < info->dlpi_phnum; i++) {
65 if (info->dlpi_phdr[i].p_type == PT_LOAD) {
66 map_start = (void *)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
67 break;
68 }
69 }
70
71 if (map_start != data->dli_fbase)
72 return 0;
73
74 for (unsigned i = 0; i < info->dlpi_phnum; i++) {
75 if (info->dlpi_phdr[i].p_type != PT_NOTE)
76 continue;
77
78 struct build_id_note *note = (void *)(info->dlpi_addr +
79 info->dlpi_phdr[i].p_vaddr);
80 ptrdiff_t len = info->dlpi_phdr[i].p_filesz;
81
82 while (len >= sizeof(struct build_id_note)) {
83 if (note->nhdr.n_type == NT_GNU_BUILD_ID &&
84 note->nhdr.n_descsz != 0 &&
85 note->nhdr.n_namesz == 4 &&
86 memcmp(note->name, "GNU", 4) == 0) {
87 data->note = note;
88 return 1;
89 }
90
91 size_t offset = sizeof(ElfW(Nhdr)) +
92 ALIGN_POT(note->nhdr.n_namesz, 4) +
93 ALIGN_POT(note->nhdr.n_descsz, 4);
94 note = (struct build_id_note *)((char *)note + offset);
95 len -= offset;
96 }
97 }
98
99 return 0;
100 }
101
102 const struct build_id_note *
build_id_find_nhdr_for_addr(const void * addr)103 build_id_find_nhdr_for_addr(const void *addr)
104 {
105 Dl_info info;
106
107 if (!dladdr(addr, &info))
108 return NULL;
109
110 if (!info.dli_fbase)
111 return NULL;
112
113 struct callback_data data = {
114 .dli_fbase = info.dli_fbase,
115 .note = NULL,
116 };
117
118 if (!dl_iterate_phdr(build_id_find_nhdr_callback, &data))
119 return NULL;
120
121 return data.note;
122 }
123
124 unsigned
build_id_length(const struct build_id_note * note)125 build_id_length(const struct build_id_note *note)
126 {
127 return note->nhdr.n_descsz;
128 }
129
130 const uint8_t *
build_id_data(const struct build_id_note * note)131 build_id_data(const struct build_id_note *note)
132 {
133 return note->build_id;
134 }
135
136 #endif
137