1 /*
2 * Copyright (C) 2024 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include "platform/bionic/macros.h"
30 #include "private/elf_note.h"
31
32 #include <string.h>
33
__get_elf_note(unsigned note_type,const char * note_name,const ElfW (Addr)note_addr,const ElfW (Phdr)* phdr_note,const ElfW (Nhdr)** note_hdr,const char ** note_desc)34 bool __get_elf_note(unsigned note_type, const char* note_name, const ElfW(Addr) note_addr,
35 const ElfW(Phdr)* phdr_note, const ElfW(Nhdr)** note_hdr,
36 const char** note_desc) {
37 if (phdr_note->p_type != PT_NOTE || !note_name || !note_addr) {
38 return false;
39 }
40
41 size_t note_name_len = strlen(note_name) + 1;
42
43 ElfW(Addr) p = note_addr;
44 ElfW(Addr) note_end = p + phdr_note->p_memsz;
45 while (p < note_end) {
46 // Parse the note and check it's structurally valid.
47 const ElfW(Nhdr)* note = reinterpret_cast<const ElfW(Nhdr)*>(p);
48 if (__builtin_add_overflow(p, sizeof(ElfW(Nhdr)), &p) || p >= note_end) {
49 return false;
50 }
51 const char* name = reinterpret_cast<const char*>(p);
52 if (__builtin_add_overflow(p, __builtin_align_up(note->n_namesz, 4), &p)) {
53 return false;
54 }
55 const char* desc = reinterpret_cast<const char*>(p);
56 if (__builtin_add_overflow(p, __builtin_align_up(note->n_descsz, 4), &p)) {
57 return false;
58 }
59 if (p > note_end) {
60 return false;
61 }
62
63 // Is this the note we're looking for?
64 if (note->n_type == note_type &&
65 note->n_namesz == note_name_len &&
66 strncmp(note_name, name, note_name_len) == 0) {
67 *note_hdr = note;
68 *note_desc = desc;
69 return true;
70 }
71 }
72 return false;
73 }
74
__find_elf_note(unsigned int note_type,const char * note_name,const ElfW (Phdr)* phdr_start,size_t phdr_ct,const ElfW (Nhdr)** note_hdr,const char ** note_desc,const ElfW (Addr)load_bias)75 bool __find_elf_note(unsigned int note_type, const char* note_name, const ElfW(Phdr)* phdr_start,
76 size_t phdr_ct, const ElfW(Nhdr)** note_hdr, const char** note_desc,
77 const ElfW(Addr) load_bias) {
78 for (size_t i = 0; i < phdr_ct; ++i) {
79 const ElfW(Phdr)* phdr = &phdr_start[i];
80
81 ElfW(Addr) note_addr = load_bias + phdr->p_vaddr;
82 if (__get_elf_note(note_type, note_name, note_addr, phdr, note_hdr, note_desc)) {
83 return true;
84 }
85 }
86
87 return false;
88 }
89