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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - lib/buildid.c
1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/buildid.h>
5 #include <linux/pagemap.h>
9 * Parse build id from the note segment. This logic can be shared between
10 * 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are
13 static inline int parse_build_id(void *page_addr
,
14 unsigned char *build_id
,
19 Elf32_Word note_offs
= 0, new_offs
;
21 /* check for overflow */
22 if (note_start
< page_addr
|| note_start
+ note_size
< note_start
)
25 /* only supports note that fits in the first page */
26 if (note_start
+ note_size
> page_addr
+ PAGE_SIZE
)
29 while (note_offs
+ sizeof(Elf32_Nhdr
) < note_size
) {
30 Elf32_Nhdr
*nhdr
= (Elf32_Nhdr
*)(note_start
+ note_offs
);
32 if (nhdr
->n_type
== BUILD_ID
&&
33 nhdr
->n_namesz
== sizeof("GNU") &&
35 nhdr
->n_descsz
<= BUILD_ID_SIZE_MAX
) {
37 note_start
+ note_offs
+
38 ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr
),
40 memset(build_id
+ nhdr
->n_descsz
, 0,
41 BUILD_ID_SIZE_MAX
- nhdr
->n_descsz
);
43 *size
= nhdr
->n_descsz
;
46 new_offs
= note_offs
+ sizeof(Elf32_Nhdr
) +
47 ALIGN(nhdr
->n_namesz
, 4) + ALIGN(nhdr
->n_descsz
, 4);
48 if (new_offs
<= note_offs
) /* overflow */
55 /* Parse build ID from 32-bit ELF */
56 static int get_build_id_32(void *page_addr
, unsigned char *build_id
,
59 Elf32_Ehdr
*ehdr
= (Elf32_Ehdr
*)page_addr
;
63 /* only supports phdr that fits in one page */
65 (PAGE_SIZE
- sizeof(Elf32_Ehdr
)) / sizeof(Elf32_Phdr
))
68 phdr
= (Elf32_Phdr
*)(page_addr
+ sizeof(Elf32_Ehdr
));
70 for (i
= 0; i
< ehdr
->e_phnum
; ++i
) {
71 if (phdr
[i
].p_type
== PT_NOTE
&&
72 !parse_build_id(page_addr
, build_id
, size
,
73 page_addr
+ phdr
[i
].p_offset
,
80 /* Parse build ID from 64-bit ELF */
81 static int get_build_id_64(void *page_addr
, unsigned char *build_id
,
84 Elf64_Ehdr
*ehdr
= (Elf64_Ehdr
*)page_addr
;
88 /* only supports phdr that fits in one page */
90 (PAGE_SIZE
- sizeof(Elf64_Ehdr
)) / sizeof(Elf64_Phdr
))
93 phdr
= (Elf64_Phdr
*)(page_addr
+ sizeof(Elf64_Ehdr
));
95 for (i
= 0; i
< ehdr
->e_phnum
; ++i
) {
96 if (phdr
[i
].p_type
== PT_NOTE
&&
97 !parse_build_id(page_addr
, build_id
, size
,
98 page_addr
+ phdr
[i
].p_offset
,
106 * Parse build ID of ELF file mapped to vma
108 * @build_id: buffer to store build id, at least BUILD_ID_SIZE long
109 * @size: returns actual build id size in case of success
111 * Returns 0 on success, otherwise error (< 0).
113 int build_id_parse(struct vm_area_struct
*vma
, unsigned char *build_id
,
121 /* only works for page backed storage */
125 page
= find_get_page(vma
->vm_file
->f_mapping
, 0);
127 return -EFAULT
; /* page not mapped */
130 page_addr
= kmap_atomic(page
);
131 ehdr
= (Elf32_Ehdr
*)page_addr
;
133 /* compare magic x7f "ELF" */
134 if (memcmp(ehdr
->e_ident
, ELFMAG
, SELFMAG
) != 0)
137 /* only support executable file and shared object file */
138 if (ehdr
->e_type
!= ET_EXEC
&& ehdr
->e_type
!= ET_DYN
)
141 if (ehdr
->e_ident
[EI_CLASS
] == ELFCLASS32
)
142 ret
= get_build_id_32(page_addr
, build_id
, size
);
143 else if (ehdr
->e_ident
[EI_CLASS
] == ELFCLASS64
)
144 ret
= get_build_id_64(page_addr
, build_id
, size
);
146 kunmap_atomic(page_addr
);