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ecd75fc8 | 1 | /* Copyright 2013-2014 Free Software Foundation, Inc. |
681f229a NB |
2 | This program is free software; you can redistribute it and/or modify |
3 | it under the terms of the GNU General Public License as published by | |
4 | the Free Software Foundation; either version 3 of the License, or | |
5 | (at your option) any later version. | |
6 | ||
7 | This program is distributed in the hope that it will be useful, | |
8 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
9 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
10 | GNU General Public License for more details. | |
11 | ||
12 | You should have received a copy of the GNU General Public License | |
13 | along with this program. If not, see <http://www.gnu.org/licenses/>. | |
14 | */ | |
15 | ||
16 | #include <unistd.h> | |
17 | #include <fcntl.h> | |
18 | #include <stdio.h> | |
19 | #include <stdlib.h> | |
20 | #include <string.h> | |
21 | #include <sys/mman.h> | |
22 | ||
23 | #include "sym-file-loader.h" | |
24 | ||
25 | #ifdef TARGET_LP64 | |
26 | ||
27 | uint8_t | |
28 | elf_st_type (uint8_t st_info) | |
29 | { | |
30 | return ELF64_ST_TYPE (st_info); | |
31 | } | |
32 | ||
33 | #elif defined TARGET_ILP32 | |
34 | ||
35 | uint8_t | |
36 | elf_st_type (uint8_t st_info) | |
37 | { | |
38 | return ELF32_ST_TYPE (st_info); | |
39 | } | |
40 | ||
41 | #endif | |
42 | ||
43 | /* Load a program segment. */ | |
44 | ||
45 | static struct segment * | |
46 | load (uint8_t *addr, Elf_External_Phdr *phdr, struct segment *tail_seg) | |
47 | { | |
48 | struct segment *seg = NULL; | |
49 | uint8_t *mapped_addr = NULL; | |
50 | void *from = NULL; | |
51 | void *to = NULL; | |
52 | ||
53 | /* For the sake of simplicity all operations are permitted. */ | |
54 | unsigned perm = PROT_READ | PROT_WRITE | PROT_EXEC; | |
55 | ||
56 | mapped_addr = (uint8_t *) mmap ((void *) GETADDR (phdr, p_vaddr), | |
57 | GET (phdr, p_memsz), perm, | |
58 | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); | |
59 | ||
60 | from = (void *) (addr + GET (phdr, p_offset)); | |
61 | to = (void *) mapped_addr; | |
62 | ||
63 | memcpy (to, from, GET (phdr, p_filesz)); | |
64 | ||
65 | seg = (struct segment *) malloc (sizeof (struct segment)); | |
66 | ||
67 | if (seg == 0) | |
68 | return 0; | |
69 | ||
70 | seg->mapped_addr = mapped_addr; | |
71 | seg->phdr = phdr; | |
72 | seg->next = 0; | |
73 | ||
74 | if (tail_seg != 0) | |
75 | tail_seg->next = seg; | |
76 | ||
77 | return seg; | |
78 | } | |
79 | ||
80 | /* Mini shared library loader. No reallocation | |
81 | is performed for the sake of simplicity. */ | |
82 | ||
83 | int | |
84 | load_shlib (const char *file, Elf_External_Ehdr **ehdr_out, | |
85 | struct segment **seg_out) | |
86 | { | |
87 | uint64_t i; | |
88 | int fd; | |
89 | off_t fsize; | |
90 | uint8_t *addr; | |
91 | Elf_External_Ehdr *ehdr; | |
92 | Elf_External_Phdr *phdr; | |
93 | struct segment *head_seg = NULL; | |
94 | struct segment *tail_seg = NULL; | |
95 | ||
96 | /* Map the lib in memory for reading. */ | |
97 | fd = open (file, O_RDONLY); | |
98 | if (fd < 0) | |
99 | { | |
100 | perror ("fopen failed."); | |
101 | return -1; | |
102 | } | |
103 | ||
104 | fsize = lseek (fd, 0, SEEK_END); | |
105 | ||
106 | if (fsize < 0) | |
107 | { | |
108 | perror ("lseek failed."); | |
109 | return -1; | |
110 | } | |
111 | ||
112 | addr = (uint8_t *) mmap (NULL, fsize, PROT_READ, MAP_PRIVATE, fd, 0); | |
113 | if (addr == (uint8_t *) -1) | |
114 | { | |
115 | perror ("mmap failed."); | |
116 | return -1; | |
117 | } | |
118 | ||
119 | /* Check if the lib is an ELF file. */ | |
120 | ehdr = (Elf_External_Ehdr *) addr; | |
121 | if (ehdr->e_ident[EI_MAG0] != ELFMAG0 | |
122 | || ehdr->e_ident[EI_MAG1] != ELFMAG1 | |
123 | || ehdr->e_ident[EI_MAG2] != ELFMAG2 | |
124 | || ehdr->e_ident[EI_MAG3] != ELFMAG3) | |
125 | { | |
126 | printf ("Not an ELF file: %x\n", ehdr->e_ident[EI_MAG0]); | |
127 | return -1; | |
128 | } | |
129 | ||
130 | if (ehdr->e_ident[EI_CLASS] == ELFCLASS32) | |
131 | { | |
132 | if (sizeof (void *) != 4) | |
133 | { | |
134 | printf ("Architecture mismatch."); | |
135 | return -1; | |
136 | } | |
137 | } | |
138 | else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64) | |
139 | { | |
140 | if (sizeof (void *) != 8) | |
141 | { | |
142 | printf ("Architecture mismatch."); | |
143 | return -1; | |
144 | } | |
145 | } | |
146 | ||
147 | /* Load the program segments. For the sake of simplicity | |
148 | assume that no reallocation is needed. */ | |
149 | phdr = (Elf_External_Phdr *) (addr + GET (ehdr, e_phoff)); | |
150 | for (i = 0; i < GET (ehdr, e_phnum); i++, phdr++) | |
151 | { | |
152 | if (GET (phdr, p_type) == PT_LOAD) | |
153 | { | |
154 | struct segment *next_seg = load (addr, phdr, tail_seg); | |
155 | if (next_seg == 0) | |
156 | continue; | |
157 | tail_seg = next_seg; | |
158 | if (head_seg == 0) | |
159 | head_seg = next_seg; | |
160 | } | |
161 | } | |
162 | *ehdr_out = ehdr; | |
163 | *seg_out = head_seg; | |
164 | return 0; | |
165 | } | |
166 | ||
167 | /* Return the section-header table. */ | |
168 | ||
169 | Elf_External_Shdr * | |
170 | find_shdrtab (Elf_External_Ehdr *ehdr) | |
171 | { | |
172 | return (Elf_External_Shdr *) (((uint8_t *) ehdr) + GET (ehdr, e_shoff)); | |
173 | } | |
174 | ||
175 | /* Return the string table of the section headers. */ | |
176 | ||
177 | const char * | |
178 | find_shstrtab (Elf_External_Ehdr *ehdr, uint64_t *size) | |
179 | { | |
180 | const Elf_External_Shdr *shdr; | |
181 | const Elf_External_Shdr *shstr; | |
182 | ||
183 | if (GET (ehdr, e_shnum) <= GET (ehdr, e_shstrndx)) | |
184 | { | |
185 | printf ("The index of the string table is corrupt."); | |
186 | return NULL; | |
187 | } | |
188 | ||
189 | shdr = find_shdrtab (ehdr); | |
190 | ||
191 | shstr = &shdr[GET (ehdr, e_shstrndx)]; | |
192 | *size = GET (shstr, sh_size); | |
193 | return ((const char *) ehdr) + GET (shstr, sh_offset); | |
194 | } | |
195 | ||
196 | /* Return the string table named SECTION. */ | |
197 | ||
198 | const char * | |
199 | find_strtab (Elf_External_Ehdr *ehdr, | |
200 | const char *section, uint64_t *strtab_size) | |
201 | { | |
202 | uint64_t shstrtab_size = 0; | |
203 | const char *shstrtab; | |
204 | uint64_t i; | |
205 | const Elf_External_Shdr *shdr = find_shdrtab (ehdr); | |
206 | ||
207 | /* Get the string table of the section headers. */ | |
208 | shstrtab = find_shstrtab (ehdr, &shstrtab_size); | |
209 | if (shstrtab == NULL) | |
210 | return NULL; | |
211 | ||
212 | for (i = 0; i < GET (ehdr, e_shnum); i++) | |
213 | { | |
214 | uint64_t name = GET (shdr + i, sh_name); | |
215 | if (GET (shdr + i, sh_type) == SHT_STRTAB && name <= shstrtab_size | |
216 | && strcmp ((const char *) &shstrtab[name], section) == 0) | |
217 | { | |
218 | *strtab_size = GET (shdr + i, sh_size); | |
219 | return ((const char *) ehdr) + GET (shdr + i, sh_offset); | |
220 | } | |
221 | ||
222 | } | |
223 | return NULL; | |
224 | } | |
225 | ||
226 | /* Return the section header named SECTION. */ | |
227 | ||
228 | Elf_External_Shdr * | |
229 | find_shdr (Elf_External_Ehdr *ehdr, const char *section) | |
230 | { | |
231 | uint64_t shstrtab_size = 0; | |
232 | const char *shstrtab; | |
233 | uint64_t i; | |
234 | ||
235 | /* Get the string table of the section headers. */ | |
236 | shstrtab = find_shstrtab (ehdr, &shstrtab_size); | |
237 | if (shstrtab == NULL) | |
238 | return NULL; | |
239 | ||
240 | Elf_External_Shdr *shdr = find_shdrtab (ehdr); | |
241 | for (i = 0; i < GET (ehdr, e_shnum); i++) | |
242 | { | |
243 | uint64_t name = GET (shdr + i, sh_name); | |
244 | if (name <= shstrtab_size) | |
245 | { | |
246 | if (strcmp ((const char *) &shstrtab[name], section) == 0) | |
247 | return &shdr[i]; | |
248 | } | |
249 | ||
250 | } | |
251 | return NULL; | |
252 | } | |
253 | ||
254 | /* Return the symbol table. */ | |
255 | ||
256 | Elf_External_Sym * | |
257 | find_symtab (Elf_External_Ehdr *ehdr, uint64_t *symtab_size) | |
258 | { | |
259 | uint64_t i; | |
260 | const Elf_External_Shdr *shdr = find_shdrtab (ehdr); | |
261 | ||
262 | for (i = 0; i < GET (ehdr, e_shnum); i++) | |
263 | { | |
264 | if (GET (shdr + i, sh_type) == SHT_SYMTAB) | |
265 | { | |
266 | *symtab_size = GET (shdr + i, sh_size) / sizeof (Elf_External_Sym); | |
267 | return (Elf_External_Sym *) (((const char *) ehdr) + | |
268 | GET (shdr + i, sh_offset)); | |
269 | } | |
270 | } | |
271 | return NULL; | |
272 | } | |
273 | ||
274 | /* Translate a file offset to an address in a loaded segment. */ | |
275 | ||
276 | int | |
277 | translate_offset (uint64_t file_offset, struct segment *seg, void **addr) | |
278 | { | |
279 | while (seg) | |
280 | { | |
281 | uint64_t p_from, p_to; | |
282 | ||
283 | Elf_External_Phdr *phdr = seg->phdr; | |
284 | ||
285 | if (phdr == NULL) | |
286 | { | |
287 | seg = seg->next; | |
288 | continue; | |
289 | } | |
290 | ||
291 | p_from = GET (phdr, p_offset); | |
292 | p_to = p_from + GET (phdr, p_filesz); | |
293 | ||
294 | if (p_from <= file_offset && file_offset < p_to) | |
295 | { | |
296 | *addr = (void *) (seg->mapped_addr + (file_offset - p_from)); | |
297 | return 0; | |
298 | } | |
299 | seg = seg->next; | |
300 | } | |
301 | ||
302 | return -1; | |
303 | } | |
304 | ||
305 | /* Lookup the address of FUNC. */ | |
306 | ||
307 | int | |
308 | lookup_function (const char *func, | |
309 | Elf_External_Ehdr *ehdr, struct segment *seg, void **addr) | |
310 | { | |
311 | const char *strtab; | |
312 | uint64_t strtab_size = 0; | |
313 | Elf_External_Sym *symtab; | |
314 | uint64_t symtab_size = 0; | |
315 | uint64_t i; | |
316 | ||
317 | /* Get the string table for the symbols. */ | |
318 | strtab = find_strtab (ehdr, ".strtab", &strtab_size); | |
319 | if (strtab == NULL) | |
320 | { | |
321 | printf (".strtab not found."); | |
322 | return -1; | |
323 | } | |
324 | ||
325 | /* Get the symbol table. */ | |
326 | symtab = find_symtab (ehdr, &symtab_size); | |
327 | if (symtab == NULL) | |
328 | { | |
329 | printf ("symbol table not found."); | |
330 | return -1; | |
331 | } | |
332 | ||
333 | for (i = 0; i < symtab_size; i++) | |
334 | { | |
335 | Elf_External_Sym *sym = &symtab[i]; | |
336 | ||
337 | if (elf_st_type (GET (sym, st_info)) != STT_FUNC) | |
338 | continue; | |
339 | ||
340 | if (GET (sym, st_name) < strtab_size) | |
341 | { | |
342 | const char *name = &strtab[GET (sym, st_name)]; | |
343 | if (strcmp (name, func) == 0) | |
344 | { | |
345 | ||
346 | uint64_t offset = GET (sym, st_value); | |
347 | return translate_offset (offset, seg, addr); | |
348 | } | |
349 | } | |
350 | } | |
351 | ||
352 | return -1; | |
353 | } |