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1 /* Postprocess module symbol versions
2  *
3  * Copyright 2003       Kai Germaschewski
4  * Copyright 2002-2004  Rusty Russell, IBM Corporation
5  * Copyright 2006-2008  Sam Ravnborg
6  * Based in part on module-init-tools/depmod.c,file2alias
7  *
8  * This software may be used and distributed according to the terms
9  * of the GNU General Public License, incorporated herein by reference.
10  *
11  * Usage: modpost vmlinux module1.o module2.o ...
12  */
13 
14 #define _GNU_SOURCE
15 #include <elf.h>
16 #include <fnmatch.h>
17 #include <stdio.h>
18 #include <ctype.h>
19 #include <string.h>
20 #include <limits.h>
21 #include <stdbool.h>
22 #include <errno.h>
23 #include "modpost.h"
24 #include "../../include/linux/license.h"
25 
26 /* Are we using CONFIG_MODVERSIONS? */
27 static bool modversions;
28 /* Is CONFIG_MODULE_SRCVERSION_ALL set? */
29 static bool all_versions;
30 /* If we are modposting external module set to 1 */
31 static bool external_module;
32 #define MODULE_SCMVERSION_SIZE 64
33 static char module_scmversion[MODULE_SCMVERSION_SIZE];
34 /* Only warn about unresolved symbols */
35 static bool warn_unresolved;
36 
37 static int sec_mismatch_count;
38 static bool sec_mismatch_warn_only = true;
39 /* ignore missing files */
40 static bool ignore_missing_files;
41 /* If set to 1, only warn (instead of error) about missing ns imports */
42 static bool allow_missing_ns_imports;
43 
44 static bool error_occurred;
45 
46 static bool extra_warn;
47 
48 /*
49  * Cut off the warnings when there are too many. This typically occurs when
50  * vmlinux is missing. ('make modules' without building vmlinux.)
51  */
52 #define MAX_UNRESOLVED_REPORTS	10
53 static unsigned int nr_unresolved;
54 
55 /* In kernel, this size is defined in linux/module.h;
56  * here we use Elf_Addr instead of long for covering cross-compile
57  */
58 
59 #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
60 
61 void __attribute__((format(printf, 2, 3)))
modpost_log(enum loglevel loglevel,const char * fmt,...)62 modpost_log(enum loglevel loglevel, const char *fmt, ...)
63 {
64 	va_list arglist;
65 
66 	switch (loglevel) {
67 	case LOG_WARN:
68 		fprintf(stderr, "WARNING: ");
69 		break;
70 	case LOG_ERROR:
71 		fprintf(stderr, "ERROR: ");
72 		break;
73 	case LOG_FATAL:
74 		fprintf(stderr, "FATAL: ");
75 		break;
76 	default: /* invalid loglevel, ignore */
77 		break;
78 	}
79 
80 	fprintf(stderr, "modpost: ");
81 
82 	va_start(arglist, fmt);
83 	vfprintf(stderr, fmt, arglist);
84 	va_end(arglist);
85 
86 	if (loglevel == LOG_FATAL)
87 		exit(1);
88 	if (loglevel == LOG_ERROR)
89 		error_occurred = true;
90 }
91 
strends(const char * str,const char * postfix)92 static inline bool strends(const char *str, const char *postfix)
93 {
94 	if (strlen(str) < strlen(postfix))
95 		return false;
96 
97 	return strcmp(str + strlen(str) - strlen(postfix), postfix) == 0;
98 }
99 
do_nofail(void * ptr,const char * expr)100 void *do_nofail(void *ptr, const char *expr)
101 {
102 	if (!ptr)
103 		fatal("Memory allocation failure: %s.\n", expr);
104 
105 	return ptr;
106 }
107 
read_text_file(const char * filename)108 char *read_text_file(const char *filename)
109 {
110 	struct stat st;
111 	size_t nbytes;
112 	int fd;
113 	char *buf;
114 
115 	fd = open(filename, O_RDONLY);
116 	if (fd < 0) {
117 		perror(filename);
118 		exit(1);
119 	}
120 
121 	if (fstat(fd, &st) < 0) {
122 		perror(filename);
123 		exit(1);
124 	}
125 
126 	buf = NOFAIL(malloc(st.st_size + 1));
127 
128 	nbytes = st.st_size;
129 
130 	while (nbytes) {
131 		ssize_t bytes_read;
132 
133 		bytes_read = read(fd, buf, nbytes);
134 		if (bytes_read < 0) {
135 			perror(filename);
136 			exit(1);
137 		}
138 
139 		nbytes -= bytes_read;
140 	}
141 	buf[st.st_size] = '\0';
142 
143 	close(fd);
144 
145 	return buf;
146 }
147 
get_line(char ** stringp)148 char *get_line(char **stringp)
149 {
150 	char *orig = *stringp, *next;
151 
152 	/* do not return the unwanted extra line at EOF */
153 	if (!orig || *orig == '\0')
154 		return NULL;
155 
156 	/* don't use strsep here, it is not available everywhere */
157 	next = strchr(orig, '\n');
158 	if (next)
159 		*next++ = '\0';
160 
161 	*stringp = next;
162 
163 	return orig;
164 }
165 
166 /* A list of all modules we processed */
167 LIST_HEAD(modules);
168 
find_module(const char * modname)169 static struct module *find_module(const char *modname)
170 {
171 	struct module *mod;
172 
173 	list_for_each_entry(mod, &modules, list) {
174 		if (strcmp(mod->name, modname) == 0)
175 			return mod;
176 	}
177 	return NULL;
178 }
179 
new_module(const char * name,size_t namelen)180 static struct module *new_module(const char *name, size_t namelen)
181 {
182 	struct module *mod;
183 
184 	mod = NOFAIL(malloc(sizeof(*mod) + namelen + 1));
185 	memset(mod, 0, sizeof(*mod));
186 
187 	INIT_LIST_HEAD(&mod->exported_symbols);
188 	INIT_LIST_HEAD(&mod->unresolved_symbols);
189 	INIT_LIST_HEAD(&mod->missing_namespaces);
190 	INIT_LIST_HEAD(&mod->imported_namespaces);
191 
192 	memcpy(mod->name, name, namelen);
193 	mod->name[namelen] = '\0';
194 	mod->is_vmlinux = (strcmp(mod->name, "vmlinux") == 0);
195 
196 	/*
197 	 * Set mod->is_gpl_compatible to true by default. If MODULE_LICENSE()
198 	 * is missing, do not check the use for EXPORT_SYMBOL_GPL() becasue
199 	 * modpost will exit wiht error anyway.
200 	 */
201 	mod->is_gpl_compatible = true;
202 
203 	list_add_tail(&mod->list, &modules);
204 
205 	return mod;
206 }
207 
208 /* A hash of all exported symbols,
209  * struct symbol is also used for lists of unresolved symbols */
210 
211 #define SYMBOL_HASH_SIZE 1024
212 
213 struct symbol {
214 	struct symbol *next;
215 	struct list_head list;	/* link to module::exported_symbols or module::unresolved_symbols */
216 	struct module *module;
217 	char *namespace;
218 	unsigned int crc;
219 	bool crc_valid;
220 	bool weak;
221 	bool is_gpl_only;	/* exported by EXPORT_SYMBOL_GPL */
222 	char name[];
223 };
224 
225 static struct symbol *symbolhash[SYMBOL_HASH_SIZE];
226 
227 /* This is based on the hash algorithm from gdbm, via tdb */
tdb_hash(const char * name)228 static inline unsigned int tdb_hash(const char *name)
229 {
230 	unsigned value;	/* Used to compute the hash value.  */
231 	unsigned   i;	/* Used to cycle through random values. */
232 
233 	/* Set the initial value from the key size. */
234 	for (value = 0x238F13AF * strlen(name), i = 0; name[i]; i++)
235 		value = (value + (((unsigned char *)name)[i] << (i*5 % 24)));
236 
237 	return (1103515243 * value + 12345);
238 }
239 
240 /**
241  * Allocate a new symbols for use in the hash of exported symbols or
242  * the list of unresolved symbols per module
243  **/
alloc_symbol(const char * name)244 static struct symbol *alloc_symbol(const char *name)
245 {
246 	struct symbol *s = NOFAIL(malloc(sizeof(*s) + strlen(name) + 1));
247 
248 	memset(s, 0, sizeof(*s));
249 	strcpy(s->name, name);
250 
251 	return s;
252 }
253 
254 /* For the hash of exported symbols */
hash_add_symbol(struct symbol * sym)255 static void hash_add_symbol(struct symbol *sym)
256 {
257 	unsigned int hash;
258 
259 	hash = tdb_hash(sym->name) % SYMBOL_HASH_SIZE;
260 	sym->next = symbolhash[hash];
261 	symbolhash[hash] = sym;
262 }
263 
sym_add_unresolved(const char * name,struct module * mod,bool weak)264 static void sym_add_unresolved(const char *name, struct module *mod, bool weak)
265 {
266 	struct symbol *sym;
267 
268 	sym = alloc_symbol(name);
269 	sym->weak = weak;
270 
271 	list_add_tail(&sym->list, &mod->unresolved_symbols);
272 }
273 
sym_find_with_module(const char * name,struct module * mod)274 static struct symbol *sym_find_with_module(const char *name, struct module *mod)
275 {
276 	struct symbol *s;
277 
278 	/* For our purposes, .foo matches foo.  PPC64 needs this. */
279 	if (name[0] == '.')
280 		name++;
281 
282 	for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s = s->next) {
283 		if (strcmp(s->name, name) == 0 && (!mod || s->module == mod))
284 			return s;
285 	}
286 	return NULL;
287 }
288 
find_symbol(const char * name)289 static struct symbol *find_symbol(const char *name)
290 {
291 	return sym_find_with_module(name, NULL);
292 }
293 
294 struct namespace_list {
295 	struct list_head list;
296 	char namespace[];
297 };
298 
contains_namespace(struct list_head * head,const char * namespace)299 static bool contains_namespace(struct list_head *head, const char *namespace)
300 {
301 	struct namespace_list *list;
302 
303 	list_for_each_entry(list, head, list) {
304 		if (!strcmp(list->namespace, namespace))
305 			return true;
306 	}
307 
308 	return false;
309 }
310 
add_namespace(struct list_head * head,const char * namespace)311 static void add_namespace(struct list_head *head, const char *namespace)
312 {
313 	struct namespace_list *ns_entry;
314 
315 	if (!contains_namespace(head, namespace)) {
316 		ns_entry = NOFAIL(malloc(sizeof(*ns_entry) +
317 					 strlen(namespace) + 1));
318 		strcpy(ns_entry->namespace, namespace);
319 		list_add_tail(&ns_entry->list, head);
320 	}
321 }
322 
sym_get_data_by_offset(const struct elf_info * info,unsigned int secindex,unsigned long offset)323 static void *sym_get_data_by_offset(const struct elf_info *info,
324 				    unsigned int secindex, unsigned long offset)
325 {
326 	Elf_Shdr *sechdr = &info->sechdrs[secindex];
327 
328 	return (void *)info->hdr + sechdr->sh_offset + offset;
329 }
330 
sym_get_data(const struct elf_info * info,const Elf_Sym * sym)331 void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym)
332 {
333 	return sym_get_data_by_offset(info, get_secindex(info, sym),
334 				      sym->st_value);
335 }
336 
sech_name(const struct elf_info * info,Elf_Shdr * sechdr)337 static const char *sech_name(const struct elf_info *info, Elf_Shdr *sechdr)
338 {
339 	return sym_get_data_by_offset(info, info->secindex_strings,
340 				      sechdr->sh_name);
341 }
342 
sec_name(const struct elf_info * info,unsigned int secindex)343 static const char *sec_name(const struct elf_info *info, unsigned int secindex)
344 {
345 	/*
346 	 * If sym->st_shndx is a special section index, there is no
347 	 * corresponding section header.
348 	 * Return "" if the index is out of range of info->sechdrs[] array.
349 	 */
350 	if (secindex >= info->num_sections)
351 		return "";
352 
353 	return sech_name(info, &info->sechdrs[secindex]);
354 }
355 
356 #define strstarts(str, prefix) (strncmp(str, prefix, strlen(prefix)) == 0)
357 
sym_update_namespace(const char * symname,const char * namespace)358 static void sym_update_namespace(const char *symname, const char *namespace)
359 {
360 	struct symbol *s = find_symbol(symname);
361 
362 	/*
363 	 * That symbol should have been created earlier and thus this is
364 	 * actually an assertion.
365 	 */
366 	if (!s) {
367 		error("Could not update namespace(%s) for symbol %s\n",
368 		      namespace, symname);
369 		return;
370 	}
371 
372 	free(s->namespace);
373 	s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL;
374 }
375 
sym_add_exported(const char * name,struct module * mod,bool gpl_only)376 static struct symbol *sym_add_exported(const char *name, struct module *mod,
377 				       bool gpl_only)
378 {
379 	struct symbol *s = find_symbol(name);
380 
381 	if (s && (!external_module || s->module->is_vmlinux || s->module == mod)) {
382 		error("%s: '%s' exported twice. Previous export was in %s%s\n",
383 		      mod->name, name, s->module->name,
384 		      s->module->is_vmlinux ? "" : ".ko");
385 	}
386 
387 	s = alloc_symbol(name);
388 	s->module = mod;
389 	s->is_gpl_only = gpl_only;
390 	list_add_tail(&s->list, &mod->exported_symbols);
391 	hash_add_symbol(s);
392 
393 	return s;
394 }
395 
sym_set_crc(struct symbol * sym,unsigned int crc)396 static void sym_set_crc(struct symbol *sym, unsigned int crc)
397 {
398 	sym->crc = crc;
399 	sym->crc_valid = true;
400 }
401 
grab_file(const char * filename,size_t * size)402 static void *grab_file(const char *filename, size_t *size)
403 {
404 	struct stat st;
405 	void *map = MAP_FAILED;
406 	int fd;
407 
408 	fd = open(filename, O_RDONLY);
409 	if (fd < 0)
410 		return NULL;
411 	if (fstat(fd, &st))
412 		goto failed;
413 
414 	*size = st.st_size;
415 	map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
416 
417 failed:
418 	close(fd);
419 	if (map == MAP_FAILED)
420 		return NULL;
421 	return map;
422 }
423 
release_file(void * file,size_t size)424 static void release_file(void *file, size_t size)
425 {
426 	munmap(file, size);
427 }
428 
parse_elf(struct elf_info * info,const char * filename)429 static int parse_elf(struct elf_info *info, const char *filename)
430 {
431 	unsigned int i;
432 	Elf_Ehdr *hdr;
433 	Elf_Shdr *sechdrs;
434 	Elf_Sym  *sym;
435 	const char *secstrings;
436 	unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U;
437 
438 	hdr = grab_file(filename, &info->size);
439 	if (!hdr) {
440 		if (ignore_missing_files) {
441 			fprintf(stderr, "%s: %s (ignored)\n", filename,
442 				strerror(errno));
443 			return 0;
444 		}
445 		perror(filename);
446 		exit(1);
447 	}
448 	info->hdr = hdr;
449 	if (info->size < sizeof(*hdr)) {
450 		/* file too small, assume this is an empty .o file */
451 		return 0;
452 	}
453 	/* Is this a valid ELF file? */
454 	if ((hdr->e_ident[EI_MAG0] != ELFMAG0) ||
455 	    (hdr->e_ident[EI_MAG1] != ELFMAG1) ||
456 	    (hdr->e_ident[EI_MAG2] != ELFMAG2) ||
457 	    (hdr->e_ident[EI_MAG3] != ELFMAG3)) {
458 		/* Not an ELF file - silently ignore it */
459 		return 0;
460 	}
461 	/* Fix endianness in ELF header */
462 	hdr->e_type      = TO_NATIVE(hdr->e_type);
463 	hdr->e_machine   = TO_NATIVE(hdr->e_machine);
464 	hdr->e_version   = TO_NATIVE(hdr->e_version);
465 	hdr->e_entry     = TO_NATIVE(hdr->e_entry);
466 	hdr->e_phoff     = TO_NATIVE(hdr->e_phoff);
467 	hdr->e_shoff     = TO_NATIVE(hdr->e_shoff);
468 	hdr->e_flags     = TO_NATIVE(hdr->e_flags);
469 	hdr->e_ehsize    = TO_NATIVE(hdr->e_ehsize);
470 	hdr->e_phentsize = TO_NATIVE(hdr->e_phentsize);
471 	hdr->e_phnum     = TO_NATIVE(hdr->e_phnum);
472 	hdr->e_shentsize = TO_NATIVE(hdr->e_shentsize);
473 	hdr->e_shnum     = TO_NATIVE(hdr->e_shnum);
474 	hdr->e_shstrndx  = TO_NATIVE(hdr->e_shstrndx);
475 	sechdrs = (void *)hdr + hdr->e_shoff;
476 	info->sechdrs = sechdrs;
477 
478 	/* modpost only works for relocatable objects */
479 	if (hdr->e_type != ET_REL)
480 		fatal("%s: not relocatable object.", filename);
481 
482 	/* Check if file offset is correct */
483 	if (hdr->e_shoff > info->size) {
484 		fatal("section header offset=%lu in file '%s' is bigger than filesize=%zu\n",
485 		      (unsigned long)hdr->e_shoff, filename, info->size);
486 		return 0;
487 	}
488 
489 	if (hdr->e_shnum == SHN_UNDEF) {
490 		/*
491 		 * There are more than 64k sections,
492 		 * read count from .sh_size.
493 		 */
494 		info->num_sections = TO_NATIVE(sechdrs[0].sh_size);
495 	}
496 	else {
497 		info->num_sections = hdr->e_shnum;
498 	}
499 	if (hdr->e_shstrndx == SHN_XINDEX) {
500 		info->secindex_strings = TO_NATIVE(sechdrs[0].sh_link);
501 	}
502 	else {
503 		info->secindex_strings = hdr->e_shstrndx;
504 	}
505 
506 	/* Fix endianness in section headers */
507 	for (i = 0; i < info->num_sections; i++) {
508 		sechdrs[i].sh_name      = TO_NATIVE(sechdrs[i].sh_name);
509 		sechdrs[i].sh_type      = TO_NATIVE(sechdrs[i].sh_type);
510 		sechdrs[i].sh_flags     = TO_NATIVE(sechdrs[i].sh_flags);
511 		sechdrs[i].sh_addr      = TO_NATIVE(sechdrs[i].sh_addr);
512 		sechdrs[i].sh_offset    = TO_NATIVE(sechdrs[i].sh_offset);
513 		sechdrs[i].sh_size      = TO_NATIVE(sechdrs[i].sh_size);
514 		sechdrs[i].sh_link      = TO_NATIVE(sechdrs[i].sh_link);
515 		sechdrs[i].sh_info      = TO_NATIVE(sechdrs[i].sh_info);
516 		sechdrs[i].sh_addralign = TO_NATIVE(sechdrs[i].sh_addralign);
517 		sechdrs[i].sh_entsize   = TO_NATIVE(sechdrs[i].sh_entsize);
518 	}
519 	/* Find symbol table. */
520 	secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset;
521 	for (i = 1; i < info->num_sections; i++) {
522 		const char *secname;
523 		int nobits = sechdrs[i].sh_type == SHT_NOBITS;
524 
525 		if (!nobits && sechdrs[i].sh_offset > info->size) {
526 			fatal("%s is truncated. sechdrs[i].sh_offset=%lu > "
527 			      "sizeof(*hrd)=%zu\n", filename,
528 			      (unsigned long)sechdrs[i].sh_offset,
529 			      sizeof(*hdr));
530 			return 0;
531 		}
532 		secname = secstrings + sechdrs[i].sh_name;
533 		if (strcmp(secname, ".modinfo") == 0) {
534 			if (nobits)
535 				fatal("%s has NOBITS .modinfo\n", filename);
536 			info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
537 			info->modinfo_len = sechdrs[i].sh_size;
538 		}
539 
540 		if (sechdrs[i].sh_type == SHT_SYMTAB) {
541 			unsigned int sh_link_idx;
542 			symtab_idx = i;
543 			info->symtab_start = (void *)hdr +
544 			    sechdrs[i].sh_offset;
545 			info->symtab_stop  = (void *)hdr +
546 			    sechdrs[i].sh_offset + sechdrs[i].sh_size;
547 			sh_link_idx = sechdrs[i].sh_link;
548 			info->strtab       = (void *)hdr +
549 			    sechdrs[sh_link_idx].sh_offset;
550 		}
551 
552 		/* 32bit section no. table? ("more than 64k sections") */
553 		if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) {
554 			symtab_shndx_idx = i;
555 			info->symtab_shndx_start = (void *)hdr +
556 			    sechdrs[i].sh_offset;
557 			info->symtab_shndx_stop  = (void *)hdr +
558 			    sechdrs[i].sh_offset + sechdrs[i].sh_size;
559 		}
560 	}
561 	if (!info->symtab_start)
562 		fatal("%s has no symtab?\n", filename);
563 
564 	/* Fix endianness in symbols */
565 	for (sym = info->symtab_start; sym < info->symtab_stop; sym++) {
566 		sym->st_shndx = TO_NATIVE(sym->st_shndx);
567 		sym->st_name  = TO_NATIVE(sym->st_name);
568 		sym->st_value = TO_NATIVE(sym->st_value);
569 		sym->st_size  = TO_NATIVE(sym->st_size);
570 	}
571 
572 	if (symtab_shndx_idx != ~0U) {
573 		Elf32_Word *p;
574 		if (symtab_idx != sechdrs[symtab_shndx_idx].sh_link)
575 			fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n",
576 			      filename, sechdrs[symtab_shndx_idx].sh_link,
577 			      symtab_idx);
578 		/* Fix endianness */
579 		for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop;
580 		     p++)
581 			*p = TO_NATIVE(*p);
582 	}
583 
584 	return 1;
585 }
586 
parse_elf_finish(struct elf_info * info)587 static void parse_elf_finish(struct elf_info *info)
588 {
589 	release_file(info->hdr, info->size);
590 }
591 
ignore_undef_symbol(struct elf_info * info,const char * symname)592 static int ignore_undef_symbol(struct elf_info *info, const char *symname)
593 {
594 	/* ignore __this_module, it will be resolved shortly */
595 	if (strcmp(symname, "__this_module") == 0)
596 		return 1;
597 	/* ignore global offset table */
598 	if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0)
599 		return 1;
600 	if (info->hdr->e_machine == EM_PPC)
601 		/* Special register function linked on all modules during final link of .ko */
602 		if (strstarts(symname, "_restgpr_") ||
603 		    strstarts(symname, "_savegpr_") ||
604 		    strstarts(symname, "_rest32gpr_") ||
605 		    strstarts(symname, "_save32gpr_") ||
606 		    strstarts(symname, "_restvr_") ||
607 		    strstarts(symname, "_savevr_"))
608 			return 1;
609 	if (info->hdr->e_machine == EM_PPC64)
610 		/* Special register function linked on all modules during final link of .ko */
611 		if (strstarts(symname, "_restgpr0_") ||
612 		    strstarts(symname, "_savegpr0_") ||
613 		    strstarts(symname, "_restvr_") ||
614 		    strstarts(symname, "_savevr_") ||
615 		    strcmp(symname, ".TOC.") == 0)
616 			return 1;
617 
618 	if (info->hdr->e_machine == EM_S390)
619 		/* Expoline thunks are linked on all kernel modules during final link of .ko */
620 		if (strstarts(symname, "__s390_indirect_jump_r"))
621 			return 1;
622 	/* Do not ignore this symbol */
623 	return 0;
624 }
625 
handle_symbol(struct module * mod,struct elf_info * info,const Elf_Sym * sym,const char * symname)626 static void handle_symbol(struct module *mod, struct elf_info *info,
627 			  const Elf_Sym *sym, const char *symname)
628 {
629 	switch (sym->st_shndx) {
630 	case SHN_COMMON:
631 		if (strstarts(symname, "__gnu_lto_")) {
632 			/* Should warn here, but modpost runs before the linker */
633 		} else
634 			warn("\"%s\" [%s] is COMMON symbol\n", symname, mod->name);
635 		break;
636 	case SHN_UNDEF:
637 		/* undefined symbol */
638 		if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL &&
639 		    ELF_ST_BIND(sym->st_info) != STB_WEAK)
640 			break;
641 		if (ignore_undef_symbol(info, symname))
642 			break;
643 		if (info->hdr->e_machine == EM_SPARC ||
644 		    info->hdr->e_machine == EM_SPARCV9) {
645 			/* Ignore register directives. */
646 			if (ELF_ST_TYPE(sym->st_info) == STT_SPARC_REGISTER)
647 				break;
648 			if (symname[0] == '.') {
649 				char *munged = NOFAIL(strdup(symname));
650 				munged[0] = '_';
651 				munged[1] = toupper(munged[1]);
652 				symname = munged;
653 			}
654 		}
655 
656 		sym_add_unresolved(symname, mod,
657 				   ELF_ST_BIND(sym->st_info) == STB_WEAK);
658 		break;
659 	default:
660 		/* All exported symbols */
661 		if (strstarts(symname, "__ksymtab_")) {
662 			const char *name, *secname;
663 
664 			name = symname + strlen("__ksymtab_");
665 			secname = sec_name(info, get_secindex(info, sym));
666 
667 			if (strstarts(secname, "___ksymtab_gpl+"))
668 				sym_add_exported(name, mod, true);
669 			else if (strstarts(secname, "___ksymtab+"))
670 				sym_add_exported(name, mod, false);
671 		}
672 		if (strcmp(symname, "init_module") == 0)
673 			mod->has_init = true;
674 		if (strcmp(symname, "cleanup_module") == 0)
675 			mod->has_cleanup = true;
676 		break;
677 	}
678 }
679 
680 /**
681  * Parse tag=value strings from .modinfo section
682  **/
next_string(char * string,unsigned long * secsize)683 static char *next_string(char *string, unsigned long *secsize)
684 {
685 	/* Skip non-zero chars */
686 	while (string[0]) {
687 		string++;
688 		if ((*secsize)-- <= 1)
689 			return NULL;
690 	}
691 
692 	/* Skip any zero padding. */
693 	while (!string[0]) {
694 		string++;
695 		if ((*secsize)-- <= 1)
696 			return NULL;
697 	}
698 	return string;
699 }
700 
get_next_modinfo(struct elf_info * info,const char * tag,char * prev)701 static char *get_next_modinfo(struct elf_info *info, const char *tag,
702 			      char *prev)
703 {
704 	char *p;
705 	unsigned int taglen = strlen(tag);
706 	char *modinfo = info->modinfo;
707 	unsigned long size = info->modinfo_len;
708 
709 	if (prev) {
710 		size -= prev - modinfo;
711 		modinfo = next_string(prev, &size);
712 	}
713 
714 	for (p = modinfo; p; p = next_string(p, &size)) {
715 		if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
716 			return p + taglen + 1;
717 	}
718 	return NULL;
719 }
720 
get_modinfo(struct elf_info * info,const char * tag)721 static char *get_modinfo(struct elf_info *info, const char *tag)
722 
723 {
724 	return get_next_modinfo(info, tag, NULL);
725 }
726 
sym_name(struct elf_info * elf,Elf_Sym * sym)727 static const char *sym_name(struct elf_info *elf, Elf_Sym *sym)
728 {
729 	if (sym)
730 		return elf->strtab + sym->st_name;
731 	else
732 		return "(unknown)";
733 }
734 
735 /*
736  * Check whether the 'string' argument matches one of the 'patterns',
737  * an array of shell wildcard patterns (glob).
738  *
739  * Return true is there is a match.
740  */
match(const char * string,const char * const patterns[])741 static bool match(const char *string, const char *const patterns[])
742 {
743 	const char *pattern;
744 
745 	while ((pattern = *patterns++)) {
746 		if (!fnmatch(pattern, string, 0))
747 			return true;
748 	}
749 
750 	return false;
751 }
752 
753 /* useful to pass patterns to match() directly */
754 #define PATTERNS(...) \
755 	({ \
756 		static const char *const patterns[] = {__VA_ARGS__, NULL}; \
757 		patterns; \
758 	})
759 
760 /* sections that we do not want to do full section mismatch check on */
761 static const char *const section_white_list[] =
762 {
763 	".comment*",
764 	".debug*",
765 	".zdebug*",		/* Compressed debug sections. */
766 	".GCC.command.line",	/* record-gcc-switches */
767 	".mdebug*",        /* alpha, score, mips etc. */
768 	".pdr",            /* alpha, score, mips etc. */
769 	".stab*",
770 	".note*",
771 	".got*",
772 	".toc*",
773 	".xt.prop",				 /* xtensa */
774 	".xt.lit",         /* xtensa */
775 	".arcextmap*",			/* arc */
776 	".gnu.linkonce.arcext*",	/* arc : modules */
777 	".cmem*",			/* EZchip */
778 	".fmt_slot*",			/* EZchip */
779 	".gnu.lto*",
780 	".discard.*",
781 	NULL
782 };
783 
784 /*
785  * This is used to find sections missing the SHF_ALLOC flag.
786  * The cause of this is often a section specified in assembler
787  * without "ax" / "aw".
788  */
check_section(const char * modname,struct elf_info * elf,Elf_Shdr * sechdr)789 static void check_section(const char *modname, struct elf_info *elf,
790 			  Elf_Shdr *sechdr)
791 {
792 	const char *sec = sech_name(elf, sechdr);
793 
794 	if (sechdr->sh_type == SHT_PROGBITS &&
795 	    sechdr->sh_size > 0 &&
796 	    !(sechdr->sh_flags & SHF_ALLOC) &&
797 	    !match(sec, section_white_list)) {
798 		warn("%s (%s): unexpected non-allocatable section.\n"
799 		     "Did you forget to use \"ax\"/\"aw\" in a .S file?\n"
800 		     "Note that for example <linux/init.h> contains\n"
801 		     "section definitions for use in .S files.\n\n",
802 		     modname, sec);
803 	}
804 }
805 
806 
807 
808 #define ALL_INIT_DATA_SECTIONS \
809 	".init.setup", ".init.rodata", ".meminit.rodata", \
810 	".init.data", ".meminit.data"
811 #define ALL_EXIT_DATA_SECTIONS \
812 	".exit.data", ".memexit.data"
813 
814 #define ALL_INIT_TEXT_SECTIONS \
815 	".init.text", ".meminit.text"
816 #define ALL_EXIT_TEXT_SECTIONS \
817 	".exit.text"
818 
819 #define ALL_PCI_INIT_SECTIONS	\
820 	".pci_fixup_early", ".pci_fixup_header", ".pci_fixup_final", \
821 	".pci_fixup_enable", ".pci_fixup_resume", \
822 	".pci_fixup_resume_early", ".pci_fixup_suspend"
823 
824 #define ALL_XXXINIT_SECTIONS MEM_INIT_SECTIONS
825 
826 #define ALL_INIT_SECTIONS INIT_SECTIONS, ALL_XXXINIT_SECTIONS
827 #define ALL_EXIT_SECTIONS EXIT_SECTIONS
828 
829 #define DATA_SECTIONS ".data", ".data.rel"
830 #define TEXT_SECTIONS ".text", ".text.*", ".sched.text", \
831 		".kprobes.text", ".cpuidle.text", ".noinstr.text", \
832 		".ltext", ".ltext.*"
833 #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \
834 		".fixup", ".entry.text", ".exception.text", \
835 		".coldtext", ".softirqentry.text"
836 
837 #define INIT_SECTIONS      ".init.*"
838 #define MEM_INIT_SECTIONS  ".meminit.*"
839 
840 #define EXIT_SECTIONS      ".exit.*"
841 
842 #define ALL_TEXT_SECTIONS  ALL_INIT_TEXT_SECTIONS, ALL_EXIT_TEXT_SECTIONS, \
843 		TEXT_SECTIONS, OTHER_TEXT_SECTIONS
844 
845 /* init data sections */
846 static const char *const init_data_sections[] =
847 	{ ALL_INIT_DATA_SECTIONS, NULL };
848 
849 /* all init sections */
850 static const char *const init_sections[] = { ALL_INIT_SECTIONS, NULL };
851 
852 /* all text sections */
853 static const char *const text_sections[] = { ALL_TEXT_SECTIONS, NULL };
854 
855 /* data section */
856 static const char *const data_sections[] = { DATA_SECTIONS, NULL };
857 
858 static const char *const head_sections[] = { ".head.text*", NULL };
859 static const char *const linker_symbols[] =
860 	{ "__init_begin", "_sinittext", "_einittext", NULL };
861 static const char *const optim_symbols[] = { "*.constprop.*", NULL };
862 
863 enum mismatch {
864 	TEXT_TO_ANY_INIT,
865 	DATA_TO_ANY_INIT,
866 	TEXT_TO_ANY_EXIT,
867 	DATA_TO_ANY_EXIT,
868 	XXXINIT_TO_SOME_INIT,
869 	ANY_INIT_TO_ANY_EXIT,
870 	ANY_EXIT_TO_ANY_INIT,
871 	EXPORT_TO_INIT_EXIT,
872 	EXTABLE_TO_NON_TEXT,
873 };
874 
875 /**
876  * Describe how to match sections on different criteria:
877  *
878  * @fromsec: Array of sections to be matched.
879  *
880  * @bad_tosec: Relocations applied to a section in @fromsec to a section in
881  * this array is forbidden (black-list).  Can be empty.
882  *
883  * @good_tosec: Relocations applied to a section in @fromsec must be
884  * targeting sections in this array (white-list).  Can be empty.
885  *
886  * @mismatch: Type of mismatch.
887  *
888  * @handler: Specific handler to call when a match is found.  If NULL,
889  * default_mismatch_handler() will be called.
890  *
891  */
892 struct sectioncheck {
893 	const char *fromsec[20];
894 	const char *bad_tosec[20];
895 	const char *good_tosec[20];
896 	enum mismatch mismatch;
897 	void (*handler)(const char *modname, struct elf_info *elf,
898 			const struct sectioncheck* const mismatch,
899 			Elf_Rela *r, Elf_Sym *sym, const char *fromsec);
900 
901 };
902 
903 static void extable_mismatch_handler(const char *modname, struct elf_info *elf,
904 				     const struct sectioncheck* const mismatch,
905 				     Elf_Rela *r, Elf_Sym *sym,
906 				     const char *fromsec);
907 
908 static const struct sectioncheck sectioncheck[] = {
909 /* Do not reference init/exit code/data from
910  * normal code and data
911  */
912 {
913 	.fromsec = { TEXT_SECTIONS, NULL },
914 	.bad_tosec = { ALL_INIT_SECTIONS, NULL },
915 	.mismatch = TEXT_TO_ANY_INIT,
916 },
917 {
918 	.fromsec = { DATA_SECTIONS, NULL },
919 	.bad_tosec = { ALL_XXXINIT_SECTIONS, NULL },
920 	.mismatch = DATA_TO_ANY_INIT,
921 },
922 {
923 	.fromsec = { DATA_SECTIONS, NULL },
924 	.bad_tosec = { INIT_SECTIONS, NULL },
925 	.mismatch = DATA_TO_ANY_INIT,
926 },
927 {
928 	.fromsec = { TEXT_SECTIONS, NULL },
929 	.bad_tosec = { ALL_EXIT_SECTIONS, NULL },
930 	.mismatch = TEXT_TO_ANY_EXIT,
931 },
932 {
933 	.fromsec = { DATA_SECTIONS, NULL },
934 	.bad_tosec = { ALL_EXIT_SECTIONS, NULL },
935 	.mismatch = DATA_TO_ANY_EXIT,
936 },
937 /* Do not reference init code/data from meminit code/data */
938 {
939 	.fromsec = { ALL_XXXINIT_SECTIONS, NULL },
940 	.bad_tosec = { INIT_SECTIONS, NULL },
941 	.mismatch = XXXINIT_TO_SOME_INIT,
942 },
943 /* Do not use exit code/data from init code */
944 {
945 	.fromsec = { ALL_INIT_SECTIONS, NULL },
946 	.bad_tosec = { ALL_EXIT_SECTIONS, NULL },
947 	.mismatch = ANY_INIT_TO_ANY_EXIT,
948 },
949 /* Do not use init code/data from exit code */
950 {
951 	.fromsec = { ALL_EXIT_SECTIONS, NULL },
952 	.bad_tosec = { ALL_INIT_SECTIONS, NULL },
953 	.mismatch = ANY_EXIT_TO_ANY_INIT,
954 },
955 {
956 	.fromsec = { ALL_PCI_INIT_SECTIONS, NULL },
957 	.bad_tosec = { INIT_SECTIONS, NULL },
958 	.mismatch = ANY_INIT_TO_ANY_EXIT,
959 },
960 /* Do not export init/exit functions or data */
961 {
962 	.fromsec = { "___ksymtab*", NULL },
963 	.bad_tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL },
964 	.mismatch = EXPORT_TO_INIT_EXIT,
965 },
966 {
967 	.fromsec = { "__ex_table", NULL },
968 	/* If you're adding any new black-listed sections in here, consider
969 	 * adding a special 'printer' for them in scripts/check_extable.
970 	 */
971 	.bad_tosec = { ".altinstr_replacement", NULL },
972 	.good_tosec = {ALL_TEXT_SECTIONS , NULL},
973 	.mismatch = EXTABLE_TO_NON_TEXT,
974 	.handler = extable_mismatch_handler,
975 }
976 };
977 
section_mismatch(const char * fromsec,const char * tosec)978 static const struct sectioncheck *section_mismatch(
979 		const char *fromsec, const char *tosec)
980 {
981 	int i;
982 
983 	/*
984 	 * The target section could be the SHT_NUL section when we're
985 	 * handling relocations to un-resolved symbols, trying to match it
986 	 * doesn't make much sense and causes build failures on parisc
987 	 * architectures.
988 	 */
989 	if (*tosec == '\0')
990 		return NULL;
991 
992 	for (i = 0; i < ARRAY_SIZE(sectioncheck); i++) {
993 		const struct sectioncheck *check = &sectioncheck[i];
994 
995 		if (match(fromsec, check->fromsec)) {
996 			if (check->bad_tosec[0] && match(tosec, check->bad_tosec))
997 				return check;
998 			if (check->good_tosec[0] && !match(tosec, check->good_tosec))
999 				return check;
1000 		}
1001 	}
1002 	return NULL;
1003 }
1004 
1005 /**
1006  * Whitelist to allow certain references to pass with no warning.
1007  *
1008  * Pattern 1:
1009  *   If a module parameter is declared __initdata and permissions=0
1010  *   then this is legal despite the warning generated.
1011  *   We cannot see value of permissions here, so just ignore
1012  *   this pattern.
1013  *   The pattern is identified by:
1014  *   tosec   = .init.data
1015  *   fromsec = .data*
1016  *   atsym   =__param*
1017  *
1018  * Pattern 1a:
1019  *   module_param_call() ops can refer to __init set function if permissions=0
1020  *   The pattern is identified by:
1021  *   tosec   = .init.text
1022  *   fromsec = .data*
1023  *   atsym   = __param_ops_*
1024  *
1025  * Pattern 3:
1026  *   Whitelist all references from .head.text to any init section
1027  *
1028  * Pattern 4:
1029  *   Some symbols belong to init section but still it is ok to reference
1030  *   these from non-init sections as these symbols don't have any memory
1031  *   allocated for them and symbol address and value are same. So even
1032  *   if init section is freed, its ok to reference those symbols.
1033  *   For ex. symbols marking the init section boundaries.
1034  *   This pattern is identified by
1035  *   refsymname = __init_begin, _sinittext, _einittext
1036  *
1037  * Pattern 5:
1038  *   GCC may optimize static inlines when fed constant arg(s) resulting
1039  *   in functions like cpumask_empty() -- generating an associated symbol
1040  *   cpumask_empty.constprop.3 that appears in the audit.  If the const that
1041  *   is passed in comes from __init, like say nmi_ipi_mask, we get a
1042  *   meaningless section warning.  May need to add isra symbols too...
1043  *   This pattern is identified by
1044  *   tosec   = init section
1045  *   fromsec = text section
1046  *   refsymname = *.constprop.*
1047  *
1048  * Pattern 6:
1049  *   Hide section mismatch warnings for ELF local symbols.  The goal
1050  *   is to eliminate false positive modpost warnings caused by
1051  *   compiler-generated ELF local symbol names such as ".LANCHOR1".
1052  *   Autogenerated symbol names bypass modpost's "Pattern 2"
1053  *   whitelisting, which relies on pattern-matching against symbol
1054  *   names to work.  (One situation where gcc can autogenerate ELF
1055  *   local symbols is when "-fsection-anchors" is used.)
1056  **/
secref_whitelist(const struct sectioncheck * mismatch,const char * fromsec,const char * fromsym,const char * tosec,const char * tosym)1057 static int secref_whitelist(const struct sectioncheck *mismatch,
1058 			    const char *fromsec, const char *fromsym,
1059 			    const char *tosec, const char *tosym)
1060 {
1061 	/* Check for pattern 1 */
1062 	if (match(tosec, init_data_sections) &&
1063 	    match(fromsec, data_sections) &&
1064 	    strstarts(fromsym, "__param"))
1065 		return 0;
1066 
1067 	/* Check for pattern 1a */
1068 	if (strcmp(tosec, ".init.text") == 0 &&
1069 	    match(fromsec, data_sections) &&
1070 	    strstarts(fromsym, "__param_ops_"))
1071 		return 0;
1072 
1073 	/* symbols in data sections that may refer to any init/exit sections */
1074 	if (match(fromsec, PATTERNS(DATA_SECTIONS)) &&
1075 	    match(tosec, PATTERNS(ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS)) &&
1076 	    match(fromsym, PATTERNS("*_template", // scsi uses *_template a lot
1077 				    "*_timer", // arm uses ops structures named _timer a lot
1078 				    "*_sht", // scsi also used *_sht to some extent
1079 				    "*_ops",
1080 				    "*_probe",
1081 				    "*_probe_one",
1082 				    "*_console")))
1083 		return 0;
1084 
1085 	/* symbols in data sections that may refer to meminit sections */
1086 	if (match(fromsec, PATTERNS(DATA_SECTIONS)) &&
1087 	    match(tosec, PATTERNS(ALL_XXXINIT_SECTIONS)) &&
1088 	    match(fromsym, PATTERNS("*driver")))
1089 		return 0;
1090 
1091 	/*
1092 	 * symbols in data sections must not refer to .exit.*, but there are
1093 	 * quite a few offenders, so hide these unless for W=1 builds until
1094 	 * these are fixed.
1095 	 */
1096 	if (!extra_warn &&
1097 	    match(fromsec, PATTERNS(DATA_SECTIONS)) &&
1098 	    match(tosec, PATTERNS(EXIT_SECTIONS)) &&
1099 	    match(fromsym, PATTERNS("*driver")))
1100 		return 0;
1101 
1102 	/* Check for pattern 3 */
1103 	if (match(fromsec, head_sections) &&
1104 	    match(tosec, init_sections))
1105 		return 0;
1106 
1107 	/* Check for pattern 4 */
1108 	if (match(tosym, linker_symbols))
1109 		return 0;
1110 
1111 	/* Check for pattern 5 */
1112 	if (match(fromsec, text_sections) &&
1113 	    match(tosec, init_sections) &&
1114 	    match(fromsym, optim_symbols))
1115 		return 0;
1116 
1117 	/* Check for pattern 6 */
1118 	if (strstarts(fromsym, ".L"))
1119 		return 0;
1120 
1121 	return 1;
1122 }
1123 
is_arm_mapping_symbol(const char * str)1124 static inline int is_arm_mapping_symbol(const char *str)
1125 {
1126 	return str[0] == '$' &&
1127 	       (str[1] == 'a' || str[1] == 'd' || str[1] == 't' || str[1] == 'x')
1128 	       && (str[2] == '\0' || str[2] == '.');
1129 }
1130 
1131 /*
1132  * If there's no name there, ignore it; likewise, ignore it if it's
1133  * one of the magic symbols emitted used by current ARM tools.
1134  *
1135  * Otherwise if find_symbols_between() returns those symbols, they'll
1136  * fail the whitelist tests and cause lots of false alarms ... fixable
1137  * only by merging __exit and __init sections into __text, bloating
1138  * the kernel (which is especially evil on embedded platforms).
1139  */
is_valid_name(struct elf_info * elf,Elf_Sym * sym)1140 static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)
1141 {
1142 	const char *name = elf->strtab + sym->st_name;
1143 
1144 	if (!name || !strlen(name))
1145 		return 0;
1146 	return !is_arm_mapping_symbol(name);
1147 }
1148 
1149 /**
1150  * Find symbol based on relocation record info.
1151  * In some cases the symbol supplied is a valid symbol so
1152  * return refsym. If st_name != 0 we assume this is a valid symbol.
1153  * In other cases the symbol needs to be looked up in the symbol table
1154  * based on section and address.
1155  *  **/
find_elf_symbol(struct elf_info * elf,Elf64_Sword addr,Elf_Sym * relsym)1156 static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr,
1157 				Elf_Sym *relsym)
1158 {
1159 	Elf_Sym *sym;
1160 	Elf_Sym *near = NULL;
1161 	Elf64_Sword distance = 20;
1162 	Elf64_Sword d;
1163 	unsigned int relsym_secindex;
1164 
1165 	if (relsym->st_name != 0)
1166 		return relsym;
1167 
1168 	/*
1169 	 * Strive to find a better symbol name, but the resulting name may not
1170 	 * match the symbol referenced in the original code.
1171 	 */
1172 	relsym_secindex = get_secindex(elf, relsym);
1173 	for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
1174 		if (get_secindex(elf, sym) != relsym_secindex)
1175 			continue;
1176 		if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
1177 			continue;
1178 		if (!is_valid_name(elf, sym))
1179 			continue;
1180 		if (sym->st_value == addr)
1181 			return sym;
1182 		/* Find a symbol nearby - addr are maybe negative */
1183 		d = sym->st_value - addr;
1184 		if (d < 0)
1185 			d = addr - sym->st_value;
1186 		if (d < distance) {
1187 			distance = d;
1188 			near = sym;
1189 		}
1190 	}
1191 	/* We need a close match */
1192 	if (distance < 20)
1193 		return near;
1194 	else
1195 		return NULL;
1196 }
1197 
1198 /*
1199  * Find symbols before or equal addr and after addr - in the section sec.
1200  * If we find two symbols with equal offset prefer one with a valid name.
1201  * The ELF format may have a better way to detect what type of symbol
1202  * it is, but this works for now.
1203  **/
find_elf_symbol2(struct elf_info * elf,Elf_Addr addr,const char * sec)1204 static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
1205 				 const char *sec)
1206 {
1207 	Elf_Sym *sym;
1208 	Elf_Sym *near = NULL;
1209 	Elf_Addr distance = ~0;
1210 
1211 	for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
1212 		const char *symsec;
1213 
1214 		if (is_shndx_special(sym->st_shndx))
1215 			continue;
1216 		symsec = sec_name(elf, get_secindex(elf, sym));
1217 		if (strcmp(symsec, sec) != 0)
1218 			continue;
1219 		if (!is_valid_name(elf, sym))
1220 			continue;
1221 		if (sym->st_value <= addr && addr - sym->st_value <= distance) {
1222 			distance = addr - sym->st_value;
1223 			near = sym;
1224 		}
1225 	}
1226 	return near;
1227 }
1228 
is_function(Elf_Sym * sym)1229 static int is_function(Elf_Sym *sym)
1230 {
1231 	if (sym)
1232 		return ELF_ST_TYPE(sym->st_info) == STT_FUNC;
1233 	else
1234 		return -1;
1235 }
1236 
get_pretty_name(int is_func,const char ** name,const char ** name_p)1237 static inline void get_pretty_name(int is_func, const char** name, const char** name_p)
1238 {
1239 	switch (is_func) {
1240 	case 0:	*name = "variable"; *name_p = ""; break;
1241 	case 1:	*name = "function"; *name_p = "()"; break;
1242 	default: *name = "(unknown reference)"; *name_p = ""; break;
1243 	}
1244 }
1245 
1246 /*
1247  * Print a warning about a section mismatch.
1248  * Try to find symbols near it so user can find it.
1249  * Check whitelist before warning - it may be a false positive.
1250  */
report_sec_mismatch(const char * modname,const struct sectioncheck * mismatch,const char * fromsec,const char * fromsym,const char * tosec,const char * tosym)1251 static void report_sec_mismatch(const char *modname,
1252 				const struct sectioncheck *mismatch,
1253 				const char *fromsec,
1254 				const char *fromsym,
1255 				const char *tosec, const char *tosym)
1256 {
1257 	sec_mismatch_count++;
1258 
1259 	switch (mismatch->mismatch) {
1260 	case TEXT_TO_ANY_INIT:
1261 	case DATA_TO_ANY_INIT:
1262 	case TEXT_TO_ANY_EXIT:
1263 	case DATA_TO_ANY_EXIT:
1264 	case XXXINIT_TO_SOME_INIT:
1265 	case ANY_INIT_TO_ANY_EXIT:
1266 	case ANY_EXIT_TO_ANY_INIT:
1267 		warn("%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n",
1268 		     modname, fromsym, fromsec, tosym, tosec);
1269 		break;
1270 	case EXPORT_TO_INIT_EXIT:
1271 		warn("%s: EXPORT_SYMBOL used for init/exit symbol: %s (section: %s)\n",
1272 		     modname, tosym, tosec);
1273 		break;
1274 	case EXTABLE_TO_NON_TEXT:
1275 		fatal("There's a special handler for this mismatch type, we should never get here.\n");
1276 		break;
1277 	}
1278 }
1279 
default_mismatch_handler(const char * modname,struct elf_info * elf,const struct sectioncheck * const mismatch,Elf_Rela * r,Elf_Sym * sym,const char * fromsec)1280 static void default_mismatch_handler(const char *modname, struct elf_info *elf,
1281 				     const struct sectioncheck* const mismatch,
1282 				     Elf_Rela *r, Elf_Sym *sym, const char *fromsec)
1283 {
1284 	const char *tosec;
1285 	Elf_Sym *to;
1286 	Elf_Sym *from;
1287 	const char *tosym;
1288 	const char *fromsym;
1289 
1290 	from = find_elf_symbol2(elf, r->r_offset, fromsec);
1291 	fromsym = sym_name(elf, from);
1292 
1293 	tosec = sec_name(elf, get_secindex(elf, sym));
1294 	to = find_elf_symbol(elf, r->r_addend, sym);
1295 	tosym = sym_name(elf, to);
1296 
1297 	/* check whitelist - we may ignore it */
1298 	if (secref_whitelist(mismatch,
1299 			     fromsec, fromsym, tosec, tosym)) {
1300 		report_sec_mismatch(modname, mismatch,
1301 				    fromsec, fromsym, tosec, tosym);
1302 	}
1303 }
1304 
is_executable_section(struct elf_info * elf,unsigned int section_index)1305 static int is_executable_section(struct elf_info* elf, unsigned int section_index)
1306 {
1307 	if (section_index >= elf->num_sections)
1308 		fatal("section_index is outside elf->num_sections!\n");
1309 
1310 	return ((elf->sechdrs[section_index].sh_flags & SHF_EXECINSTR) == SHF_EXECINSTR);
1311 }
1312 
report_extable_warnings(const char * modname,struct elf_info * elf,const struct sectioncheck * const mismatch,Elf_Rela * r,Elf_Sym * sym,const char * fromsec,const char * tosec)1313 static void report_extable_warnings(const char* modname, struct elf_info* elf,
1314 				    const struct sectioncheck* const mismatch,
1315 				    Elf_Rela* r, Elf_Sym* sym,
1316 				    const char* fromsec, const char* tosec)
1317 {
1318 	Elf_Sym* fromsym = find_elf_symbol2(elf, r->r_offset, fromsec);
1319 	const char* fromsym_name = sym_name(elf, fromsym);
1320 	Elf_Sym* tosym = find_elf_symbol(elf, r->r_addend, sym);
1321 	const char* tosym_name = sym_name(elf, tosym);
1322 	const char* from_pretty_name;
1323 	const char* from_pretty_name_p;
1324 	const char* to_pretty_name;
1325 	const char* to_pretty_name_p;
1326 
1327 	get_pretty_name(is_function(fromsym),
1328 			&from_pretty_name, &from_pretty_name_p);
1329 	get_pretty_name(is_function(tosym),
1330 			&to_pretty_name, &to_pretty_name_p);
1331 
1332 	warn("%s(%s+0x%lx): Section mismatch in reference"
1333 	     " from the %s %s%s to the %s %s:%s%s\n",
1334 	     modname, fromsec, (long)r->r_offset, from_pretty_name,
1335 	     fromsym_name, from_pretty_name_p,
1336 	     to_pretty_name, tosec, tosym_name, to_pretty_name_p);
1337 
1338 	if (!match(tosec, mismatch->bad_tosec) &&
1339 	    is_executable_section(elf, get_secindex(elf, sym)))
1340 		fprintf(stderr,
1341 			"The relocation at %s+0x%lx references\n"
1342 			"section \"%s\" which is not in the list of\n"
1343 			"authorized sections.  If you're adding a new section\n"
1344 			"and/or if this reference is valid, add \"%s\" to the\n"
1345 			"list of authorized sections to jump to on fault.\n"
1346 			"This can be achieved by adding \"%s\" to \n"
1347 			"OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.\n",
1348 			fromsec, (long)r->r_offset, tosec, tosec, tosec);
1349 }
1350 
extable_mismatch_handler(const char * modname,struct elf_info * elf,const struct sectioncheck * const mismatch,Elf_Rela * r,Elf_Sym * sym,const char * fromsec)1351 static void extable_mismatch_handler(const char* modname, struct elf_info *elf,
1352 				     const struct sectioncheck* const mismatch,
1353 				     Elf_Rela* r, Elf_Sym* sym,
1354 				     const char *fromsec)
1355 {
1356 	const char* tosec = sec_name(elf, get_secindex(elf, sym));
1357 
1358 	sec_mismatch_count++;
1359 
1360 	report_extable_warnings(modname, elf, mismatch, r, sym, fromsec, tosec);
1361 
1362 	if (match(tosec, mismatch->bad_tosec))
1363 		fatal("The relocation at %s+0x%lx references\n"
1364 		      "section \"%s\" which is black-listed.\n"
1365 		      "Something is seriously wrong and should be fixed.\n"
1366 		      "You might get more information about where this is\n"
1367 		      "coming from by using scripts/check_extable.sh %s\n",
1368 		      fromsec, (long)r->r_offset, tosec, modname);
1369 	else if (!is_executable_section(elf, get_secindex(elf, sym)))
1370 		error("%s+0x%lx references non-executable section '%s'\n",
1371 		      fromsec, (long)r->r_offset, tosec);
1372 }
1373 
check_section_mismatch(const char * modname,struct elf_info * elf,Elf_Rela * r,Elf_Sym * sym,const char * fromsec)1374 static void check_section_mismatch(const char *modname, struct elf_info *elf,
1375 				   Elf_Rela *r, Elf_Sym *sym, const char *fromsec)
1376 {
1377 	const char *tosec = sec_name(elf, get_secindex(elf, sym));
1378 	const struct sectioncheck *mismatch = section_mismatch(fromsec, tosec);
1379 
1380 	if (mismatch) {
1381 		if (mismatch->handler)
1382 			mismatch->handler(modname, elf,  mismatch,
1383 					  r, sym, fromsec);
1384 		else
1385 			default_mismatch_handler(modname, elf, mismatch,
1386 						 r, sym, fromsec);
1387 	}
1388 }
1389 
reloc_location(struct elf_info * elf,Elf_Shdr * sechdr,Elf_Rela * r)1390 static unsigned int *reloc_location(struct elf_info *elf,
1391 				    Elf_Shdr *sechdr, Elf_Rela *r)
1392 {
1393 	return sym_get_data_by_offset(elf, sechdr->sh_info, r->r_offset);
1394 }
1395 
addend_386_rel(struct elf_info * elf,Elf_Shdr * sechdr,Elf_Rela * r)1396 static int addend_386_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
1397 {
1398 	unsigned int r_typ = ELF_R_TYPE(r->r_info);
1399 	unsigned int *location = reloc_location(elf, sechdr, r);
1400 
1401 	switch (r_typ) {
1402 	case R_386_32:
1403 		r->r_addend = TO_NATIVE(*location);
1404 		break;
1405 	case R_386_PC32:
1406 		r->r_addend = TO_NATIVE(*location) + 4;
1407 		break;
1408 	}
1409 	return 0;
1410 }
1411 
1412 #ifndef R_ARM_CALL
1413 #define R_ARM_CALL	28
1414 #endif
1415 #ifndef R_ARM_JUMP24
1416 #define R_ARM_JUMP24	29
1417 #endif
1418 
1419 #ifndef	R_ARM_THM_CALL
1420 #define	R_ARM_THM_CALL		10
1421 #endif
1422 #ifndef	R_ARM_THM_JUMP24
1423 #define	R_ARM_THM_JUMP24	30
1424 #endif
1425 #ifndef	R_ARM_THM_JUMP19
1426 #define	R_ARM_THM_JUMP19	51
1427 #endif
1428 
sign_extend32(int32_t value,int index)1429 static int32_t sign_extend32(int32_t value, int index)
1430 {
1431 	uint8_t shift = 31 - index;
1432 
1433 	return (int32_t)(value << shift) >> shift;
1434 }
1435 
addend_arm_rel(struct elf_info * elf,Elf_Shdr * sechdr,Elf_Rela * r)1436 static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
1437 {
1438 	unsigned int r_typ = ELF_R_TYPE(r->r_info);
1439 	Elf_Sym *sym = elf->symtab_start + ELF_R_SYM(r->r_info);
1440 	void *loc = reloc_location(elf, sechdr, r);
1441 	uint32_t inst;
1442 	int32_t offset;
1443 
1444 	switch (r_typ) {
1445 	case R_ARM_ABS32:
1446 		inst = TO_NATIVE(*(uint32_t *)loc);
1447 		r->r_addend = inst + sym->st_value;
1448 		break;
1449 	case R_ARM_PC24:
1450 	case R_ARM_CALL:
1451 	case R_ARM_JUMP24:
1452 		inst = TO_NATIVE(*(uint32_t *)loc);
1453 		offset = sign_extend32((inst & 0x00ffffff) << 2, 25);
1454 		r->r_addend = offset + sym->st_value + 8;
1455 		break;
1456 	case R_ARM_THM_CALL:
1457 	case R_ARM_THM_JUMP24:
1458 	case R_ARM_THM_JUMP19:
1459 		/* From ARM ABI: ((S + A) | T) - P */
1460 		r->r_addend = (int)(long)(elf->hdr +
1461 			      sechdr->sh_offset +
1462 			      (r->r_offset - sechdr->sh_addr));
1463 		break;
1464 	default:
1465 		return 1;
1466 	}
1467 	return 0;
1468 }
1469 
addend_mips_rel(struct elf_info * elf,Elf_Shdr * sechdr,Elf_Rela * r)1470 static int addend_mips_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
1471 {
1472 	unsigned int r_typ = ELF_R_TYPE(r->r_info);
1473 	unsigned int *location = reloc_location(elf, sechdr, r);
1474 	unsigned int inst;
1475 
1476 	if (r_typ == R_MIPS_HI16)
1477 		return 1;	/* skip this */
1478 	inst = TO_NATIVE(*location);
1479 	switch (r_typ) {
1480 	case R_MIPS_LO16:
1481 		r->r_addend = inst & 0xffff;
1482 		break;
1483 	case R_MIPS_26:
1484 		r->r_addend = (inst & 0x03ffffff) << 2;
1485 		break;
1486 	case R_MIPS_32:
1487 		r->r_addend = inst;
1488 		break;
1489 	}
1490 	return 0;
1491 }
1492 
1493 #ifndef EM_RISCV
1494 #define EM_RISCV		243
1495 #endif
1496 
1497 #ifndef R_RISCV_SUB32
1498 #define R_RISCV_SUB32		39
1499 #endif
1500 
section_rela(const char * modname,struct elf_info * elf,Elf_Shdr * sechdr)1501 static void section_rela(const char *modname, struct elf_info *elf,
1502 			 Elf_Shdr *sechdr)
1503 {
1504 	Elf_Sym  *sym;
1505 	Elf_Rela *rela;
1506 	Elf_Rela r;
1507 	unsigned int r_sym;
1508 	const char *fromsec;
1509 
1510 	Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset;
1511 	Elf_Rela *stop  = (void *)start + sechdr->sh_size;
1512 
1513 	fromsec = sec_name(elf, sechdr->sh_info);
1514 	/* if from section (name) is know good then skip it */
1515 	if (match(fromsec, section_white_list))
1516 		return;
1517 
1518 	for (rela = start; rela < stop; rela++) {
1519 		r.r_offset = TO_NATIVE(rela->r_offset);
1520 #if KERNEL_ELFCLASS == ELFCLASS64
1521 		if (elf->hdr->e_machine == EM_MIPS) {
1522 			unsigned int r_typ;
1523 			r_sym = ELF64_MIPS_R_SYM(rela->r_info);
1524 			r_sym = TO_NATIVE(r_sym);
1525 			r_typ = ELF64_MIPS_R_TYPE(rela->r_info);
1526 			r.r_info = ELF64_R_INFO(r_sym, r_typ);
1527 		} else {
1528 			r.r_info = TO_NATIVE(rela->r_info);
1529 			r_sym = ELF_R_SYM(r.r_info);
1530 		}
1531 #else
1532 		r.r_info = TO_NATIVE(rela->r_info);
1533 		r_sym = ELF_R_SYM(r.r_info);
1534 #endif
1535 		r.r_addend = TO_NATIVE(rela->r_addend);
1536 		switch (elf->hdr->e_machine) {
1537 		case EM_RISCV:
1538 			if (!strcmp("__ex_table", fromsec) &&
1539 			    ELF_R_TYPE(r.r_info) == R_RISCV_SUB32)
1540 				continue;
1541 			break;
1542 		}
1543 		sym = elf->symtab_start + r_sym;
1544 		/* Skip special sections */
1545 		if (is_shndx_special(sym->st_shndx))
1546 			continue;
1547 		check_section_mismatch(modname, elf, &r, sym, fromsec);
1548 	}
1549 }
1550 
section_rel(const char * modname,struct elf_info * elf,Elf_Shdr * sechdr)1551 static void section_rel(const char *modname, struct elf_info *elf,
1552 			Elf_Shdr *sechdr)
1553 {
1554 	Elf_Sym *sym;
1555 	Elf_Rel *rel;
1556 	Elf_Rela r;
1557 	unsigned int r_sym;
1558 	const char *fromsec;
1559 
1560 	Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset;
1561 	Elf_Rel *stop  = (void *)start + sechdr->sh_size;
1562 
1563 	fromsec = sec_name(elf, sechdr->sh_info);
1564 	/* if from section (name) is know good then skip it */
1565 	if (match(fromsec, section_white_list))
1566 		return;
1567 
1568 	for (rel = start; rel < stop; rel++) {
1569 		r.r_offset = TO_NATIVE(rel->r_offset);
1570 #if KERNEL_ELFCLASS == ELFCLASS64
1571 		if (elf->hdr->e_machine == EM_MIPS) {
1572 			unsigned int r_typ;
1573 			r_sym = ELF64_MIPS_R_SYM(rel->r_info);
1574 			r_sym = TO_NATIVE(r_sym);
1575 			r_typ = ELF64_MIPS_R_TYPE(rel->r_info);
1576 			r.r_info = ELF64_R_INFO(r_sym, r_typ);
1577 		} else {
1578 			r.r_info = TO_NATIVE(rel->r_info);
1579 			r_sym = ELF_R_SYM(r.r_info);
1580 		}
1581 #else
1582 		r.r_info = TO_NATIVE(rel->r_info);
1583 		r_sym = ELF_R_SYM(r.r_info);
1584 #endif
1585 		r.r_addend = 0;
1586 		switch (elf->hdr->e_machine) {
1587 		case EM_386:
1588 			if (addend_386_rel(elf, sechdr, &r))
1589 				continue;
1590 			break;
1591 		case EM_ARM:
1592 			if (addend_arm_rel(elf, sechdr, &r))
1593 				continue;
1594 			break;
1595 		case EM_MIPS:
1596 			if (addend_mips_rel(elf, sechdr, &r))
1597 				continue;
1598 			break;
1599 		}
1600 		sym = elf->symtab_start + r_sym;
1601 		/* Skip special sections */
1602 		if (is_shndx_special(sym->st_shndx))
1603 			continue;
1604 		check_section_mismatch(modname, elf, &r, sym, fromsec);
1605 	}
1606 }
1607 
1608 /**
1609  * A module includes a number of sections that are discarded
1610  * either when loaded or when used as built-in.
1611  * For loaded modules all functions marked __init and all data
1612  * marked __initdata will be discarded when the module has been initialized.
1613  * Likewise for modules used built-in the sections marked __exit
1614  * are discarded because __exit marked function are supposed to be called
1615  * only when a module is unloaded which never happens for built-in modules.
1616  * The check_sec_ref() function traverses all relocation records
1617  * to find all references to a section that reference a section that will
1618  * be discarded and warns about it.
1619  **/
check_sec_ref(const char * modname,struct elf_info * elf)1620 static void check_sec_ref(const char *modname, struct elf_info *elf)
1621 {
1622 	int i;
1623 	Elf_Shdr *sechdrs = elf->sechdrs;
1624 
1625 	/* Walk through all sections */
1626 	for (i = 0; i < elf->num_sections; i++) {
1627 		check_section(modname, elf, &elf->sechdrs[i]);
1628 		/* We want to process only relocation sections and not .init */
1629 		if (sechdrs[i].sh_type == SHT_RELA)
1630 			section_rela(modname, elf, &elf->sechdrs[i]);
1631 		else if (sechdrs[i].sh_type == SHT_REL)
1632 			section_rel(modname, elf, &elf->sechdrs[i]);
1633 	}
1634 }
1635 
remove_dot(char * s)1636 static char *remove_dot(char *s)
1637 {
1638 	size_t n = strcspn(s, ".");
1639 
1640 	if (n && s[n]) {
1641 		size_t m = strspn(s + n + 1, "0123456789");
1642 		if (m && (s[n + m + 1] == '.' || s[n + m + 1] == 0))
1643 			s[n] = 0;
1644 	}
1645 	return s;
1646 }
1647 
1648 /*
1649  * The CRCs are recorded in .*.cmd files in the form of:
1650  * #SYMVER <name> <crc>
1651  */
extract_crcs_for_object(const char * object,struct module * mod)1652 static void extract_crcs_for_object(const char *object, struct module *mod)
1653 {
1654 	char cmd_file[PATH_MAX];
1655 	char *buf, *p;
1656 	const char *base;
1657 	int dirlen, ret;
1658 
1659 	base = strrchr(object, '/');
1660 	if (base) {
1661 		base++;
1662 		dirlen = base - object;
1663 	} else {
1664 		dirlen = 0;
1665 		base = object;
1666 	}
1667 
1668 	ret = snprintf(cmd_file, sizeof(cmd_file), "%.*s.%s.cmd",
1669 		       dirlen, object, base);
1670 	if (ret >= sizeof(cmd_file)) {
1671 		error("%s: too long path was truncated\n", cmd_file);
1672 		return;
1673 	}
1674 
1675 	buf = read_text_file(cmd_file);
1676 	p = buf;
1677 
1678 	while ((p = strstr(p, "\n#SYMVER "))) {
1679 		char *name;
1680 		size_t namelen;
1681 		unsigned int crc;
1682 		struct symbol *sym;
1683 
1684 		name = p + strlen("\n#SYMVER ");
1685 
1686 		p = strchr(name, ' ');
1687 		if (!p)
1688 			break;
1689 
1690 		namelen = p - name;
1691 		p++;
1692 
1693 		if (!isdigit(*p))
1694 			continue;	/* skip this line */
1695 
1696 		crc = strtoul(p, &p, 0);
1697 		if (*p != '\n')
1698 			continue;	/* skip this line */
1699 
1700 		name[namelen] = '\0';
1701 
1702 		/*
1703 		 * sym_find_with_module() may return NULL here.
1704 		 * It typically occurs when CONFIG_TRIM_UNUSED_KSYMS=y.
1705 		 * Since commit e1327a127703, genksyms calculates CRCs of all
1706 		 * symbols, including trimmed ones. Ignore orphan CRCs.
1707 		 */
1708 		sym = sym_find_with_module(name, mod);
1709 		if (sym)
1710 			sym_set_crc(sym, crc);
1711 	}
1712 
1713 	free(buf);
1714 }
1715 
1716 /*
1717  * The symbol versions (CRC) are recorded in the .*.cmd files.
1718  * Parse them to retrieve CRCs for the current module.
1719  */
mod_set_crcs(struct module * mod)1720 static void mod_set_crcs(struct module *mod)
1721 {
1722 	char objlist[PATH_MAX];
1723 	char *buf, *p, *obj;
1724 	int ret;
1725 
1726 	if (mod->is_vmlinux) {
1727 		strcpy(objlist, ".vmlinux.objs");
1728 	} else {
1729 		/* objects for a module are listed in the *.mod file. */
1730 		ret = snprintf(objlist, sizeof(objlist), "%s.mod", mod->name);
1731 		if (ret >= sizeof(objlist)) {
1732 			error("%s: too long path was truncated\n", objlist);
1733 			return;
1734 		}
1735 	}
1736 
1737 	buf = read_text_file(objlist);
1738 	p = buf;
1739 
1740 	while ((obj = strsep(&p, "\n")) && obj[0])
1741 		extract_crcs_for_object(obj, mod);
1742 
1743 	free(buf);
1744 }
1745 
read_symbols(const char * modname)1746 static void read_symbols(const char *modname)
1747 {
1748 	const char *symname;
1749 	char *version;
1750 	char *license;
1751 	char *namespace;
1752 	struct module *mod;
1753 	struct elf_info info = { };
1754 	Elf_Sym *sym;
1755 
1756 	if (!parse_elf(&info, modname))
1757 		return;
1758 
1759 	if (!strends(modname, ".o")) {
1760 		error("%s: filename must be suffixed with .o\n", modname);
1761 		return;
1762 	}
1763 
1764 	/* strip trailing .o */
1765 	mod = new_module(modname, strlen(modname) - strlen(".o"));
1766 
1767 	if (!mod->is_vmlinux) {
1768 		license = get_modinfo(&info, "license");
1769 		if (!license)
1770 			error("missing MODULE_LICENSE() in %s\n", modname);
1771 		while (license) {
1772 			if (!license_is_gpl_compatible(license)) {
1773 				mod->is_gpl_compatible = false;
1774 				break;
1775 			}
1776 			license = get_next_modinfo(&info, "license", license);
1777 		}
1778 
1779 		namespace = get_modinfo(&info, "import_ns");
1780 		while (namespace) {
1781 			add_namespace(&mod->imported_namespaces, namespace);
1782 			namespace = get_next_modinfo(&info, "import_ns",
1783 						     namespace);
1784 		}
1785 	}
1786 
1787 	for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
1788 		symname = remove_dot(info.strtab + sym->st_name);
1789 
1790 		handle_symbol(mod, &info, sym, symname);
1791 		handle_moddevtable(mod, &info, sym, symname);
1792 	}
1793 
1794 	for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
1795 		symname = remove_dot(info.strtab + sym->st_name);
1796 
1797 		/* Apply symbol namespaces from __kstrtabns_<symbol> entries. */
1798 		if (strstarts(symname, "__kstrtabns_"))
1799 			sym_update_namespace(symname + strlen("__kstrtabns_"),
1800 					     sym_get_data(&info, sym));
1801 	}
1802 
1803 	check_sec_ref(modname, &info);
1804 
1805 	if (!mod->is_vmlinux) {
1806 		version = get_modinfo(&info, "version");
1807 		if (version || all_versions)
1808 			get_src_version(mod->name, mod->srcversion,
1809 					sizeof(mod->srcversion) - 1);
1810 	}
1811 
1812 	parse_elf_finish(&info);
1813 
1814 	if (modversions) {
1815 		/*
1816 		 * Our trick to get versioning for module struct etc. - it's
1817 		 * never passed as an argument to an exported function, so
1818 		 * the automatic versioning doesn't pick it up, but it's really
1819 		 * important anyhow.
1820 		 */
1821 		sym_add_unresolved("module_layout", mod, false);
1822 
1823 		mod_set_crcs(mod);
1824 	}
1825 }
1826 
read_symbols_from_files(const char * filename)1827 static void read_symbols_from_files(const char *filename)
1828 {
1829 	FILE *in = stdin;
1830 	char fname[PATH_MAX];
1831 
1832 	if (strcmp(filename, "-") != 0) {
1833 		in = fopen(filename, "r");
1834 		if (!in)
1835 			fatal("Can't open filenames file %s: %m", filename);
1836 	}
1837 
1838 	while (fgets(fname, PATH_MAX, in) != NULL) {
1839 		if (strends(fname, "\n"))
1840 			fname[strlen(fname)-1] = '\0';
1841 		read_symbols(fname);
1842 	}
1843 
1844 	if (in != stdin)
1845 		fclose(in);
1846 }
1847 
1848 #define SZ 500
1849 
1850 /* We first write the generated file into memory using the
1851  * following helper, then compare to the file on disk and
1852  * only update the later if anything changed */
1853 
buf_printf(struct buffer * buf,const char * fmt,...)1854 void __attribute__((format(printf, 2, 3))) buf_printf(struct buffer *buf,
1855 						      const char *fmt, ...)
1856 {
1857 	char tmp[SZ];
1858 	int len;
1859 	va_list ap;
1860 
1861 	va_start(ap, fmt);
1862 	len = vsnprintf(tmp, SZ, fmt, ap);
1863 	buf_write(buf, tmp, len);
1864 	va_end(ap);
1865 }
1866 
buf_write(struct buffer * buf,const char * s,int len)1867 void buf_write(struct buffer *buf, const char *s, int len)
1868 {
1869 	if (buf->size - buf->pos < len) {
1870 		buf->size += len + SZ;
1871 		buf->p = NOFAIL(realloc(buf->p, buf->size));
1872 	}
1873 	strncpy(buf->p + buf->pos, s, len);
1874 	buf->pos += len;
1875 }
1876 
check_exports(struct module * mod)1877 static void check_exports(struct module *mod)
1878 {
1879 	struct symbol *s, *exp;
1880 
1881 	list_for_each_entry(s, &mod->unresolved_symbols, list) {
1882 		const char *basename;
1883 		exp = find_symbol(s->name);
1884 		if (!exp) {
1885 			if (!s->weak && nr_unresolved++ < MAX_UNRESOLVED_REPORTS)
1886 				modpost_log(warn_unresolved ? LOG_WARN : LOG_ERROR,
1887 					    "\"%s\" [%s.ko] undefined!\n",
1888 					    s->name, mod->name);
1889 			continue;
1890 		}
1891 		if (exp->module == mod) {
1892 			error("\"%s\" [%s.ko] was exported without definition\n",
1893 			      s->name, mod->name);
1894 			continue;
1895 		}
1896 
1897 		s->module = exp->module;
1898 		s->crc_valid = exp->crc_valid;
1899 		s->crc = exp->crc;
1900 
1901 		basename = strrchr(mod->name, '/');
1902 		if (basename)
1903 			basename++;
1904 		else
1905 			basename = mod->name;
1906 
1907 		if (exp->namespace &&
1908 		    !contains_namespace(&mod->imported_namespaces, exp->namespace)) {
1909 			modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR,
1910 				    "module %s uses symbol %s from namespace %s, but does not import it.\n",
1911 				    basename, exp->name, exp->namespace);
1912 			add_namespace(&mod->missing_namespaces, exp->namespace);
1913 		}
1914 
1915 		if (!mod->is_gpl_compatible && exp->is_gpl_only)
1916 			error("GPL-incompatible module %s.ko uses GPL-only symbol '%s'\n",
1917 			      basename, exp->name);
1918 	}
1919 }
1920 
check_modname_len(struct module * mod)1921 static void check_modname_len(struct module *mod)
1922 {
1923 	const char *mod_name;
1924 
1925 	mod_name = strrchr(mod->name, '/');
1926 	if (mod_name == NULL)
1927 		mod_name = mod->name;
1928 	else
1929 		mod_name++;
1930 	if (strlen(mod_name) >= MODULE_NAME_LEN)
1931 		error("module name is too long [%s.ko]\n", mod->name);
1932 }
1933 
1934 /**
1935  * Header for the generated file
1936  **/
add_header(struct buffer * b,struct module * mod)1937 static void add_header(struct buffer *b, struct module *mod)
1938 {
1939 	buf_printf(b, "#include <linux/module.h>\n");
1940 	/*
1941 	 * Include build-salt.h after module.h in order to
1942 	 * inherit the definitions.
1943 	 */
1944 	buf_printf(b, "#define INCLUDE_VERMAGIC\n");
1945 	buf_printf(b, "#include <linux/build-salt.h>\n");
1946 	buf_printf(b, "#include <linux/elfnote-lto.h>\n");
1947 	buf_printf(b, "#include <linux/export-internal.h>\n");
1948 	buf_printf(b, "#include <linux/vermagic.h>\n");
1949 	buf_printf(b, "#include <linux/compiler.h>\n");
1950 	buf_printf(b, "\n");
1951 	buf_printf(b, "BUILD_SALT;\n");
1952 	buf_printf(b, "BUILD_LTO_INFO;\n");
1953 	buf_printf(b, "\n");
1954 	buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n");
1955 	buf_printf(b, "MODULE_INFO(name, KBUILD_MODNAME);\n");
1956 	buf_printf(b, "\n");
1957 	buf_printf(b, "__visible struct module __this_module\n");
1958 	buf_printf(b, "__section(\".gnu.linkonce.this_module\") = {\n");
1959 	buf_printf(b, "\t.name = KBUILD_MODNAME,\n");
1960 	if (mod->has_init)
1961 		buf_printf(b, "\t.init = init_module,\n");
1962 	if (mod->has_cleanup)
1963 		buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n"
1964 			      "\t.exit = cleanup_module,\n"
1965 			      "#endif\n");
1966 	buf_printf(b, "\t.arch = MODULE_ARCH_INIT,\n");
1967 	buf_printf(b, "};\n");
1968 
1969 	if (!external_module)
1970 		buf_printf(b, "\nMODULE_INFO(intree, \"Y\");\n");
1971 
1972 	if (module_scmversion[0] != '\0')
1973 		buf_printf(b, "\nMODULE_INFO(scmversion, \"%s\");\n", module_scmversion);
1974 
1975 	buf_printf(b,
1976 		   "\n"
1977 		   "#ifdef CONFIG_RETPOLINE\n"
1978 		   "MODULE_INFO(retpoline, \"Y\");\n"
1979 		   "#endif\n");
1980 
1981 	if (strstarts(mod->name, "drivers/staging"))
1982 		buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
1983 
1984 	if (strstarts(mod->name, "tools/testing"))
1985 		buf_printf(b, "\nMODULE_INFO(test, \"Y\");\n");
1986 }
1987 
add_exported_symbols(struct buffer * buf,struct module * mod)1988 static void add_exported_symbols(struct buffer *buf, struct module *mod)
1989 {
1990 	struct symbol *sym;
1991 
1992 	if (!modversions)
1993 		return;
1994 
1995 	/* record CRCs for exported symbols */
1996 	buf_printf(buf, "\n");
1997 	list_for_each_entry(sym, &mod->exported_symbols, list) {
1998 		if (!sym->crc_valid)
1999 			warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n"
2000 			     "Is \"%s\" prototyped in <asm/asm-prototypes.h>?\n",
2001 			     sym->name, mod->name, mod->is_vmlinux ? "" : ".ko",
2002 			     sym->name);
2003 
2004 		buf_printf(buf, "SYMBOL_CRC(%s, 0x%08x, \"%s\");\n",
2005 			   sym->name, sym->crc, sym->is_gpl_only ? "_gpl" : "");
2006 	}
2007 }
2008 
2009 /**
2010  * Record CRCs for unresolved symbols
2011  **/
add_versions(struct buffer * b,struct module * mod)2012 static void add_versions(struct buffer *b, struct module *mod)
2013 {
2014 	struct symbol *s;
2015 
2016 	if (!modversions)
2017 		return;
2018 
2019 	buf_printf(b, "\n");
2020 	buf_printf(b, "static const struct modversion_info ____versions[]\n");
2021 	buf_printf(b, "__used __section(\"__versions\") = {\n");
2022 
2023 	list_for_each_entry(s, &mod->unresolved_symbols, list) {
2024 		if (!s->module)
2025 			continue;
2026 		if (!s->crc_valid) {
2027 			warn("\"%s\" [%s.ko] has no CRC!\n",
2028 				s->name, mod->name);
2029 			continue;
2030 		}
2031 		if (strlen(s->name) >= MODULE_NAME_LEN) {
2032 			error("too long symbol \"%s\" [%s.ko]\n",
2033 			      s->name, mod->name);
2034 			break;
2035 		}
2036 		buf_printf(b, "\t{ %#8x, \"%s\" },\n",
2037 			   s->crc, s->name);
2038 	}
2039 
2040 	buf_printf(b, "};\n");
2041 }
2042 
add_depends(struct buffer * b,struct module * mod)2043 static void add_depends(struct buffer *b, struct module *mod)
2044 {
2045 	struct symbol *s;
2046 	int first = 1;
2047 
2048 	/* Clear ->seen flag of modules that own symbols needed by this. */
2049 	list_for_each_entry(s, &mod->unresolved_symbols, list) {
2050 		if (s->module)
2051 			s->module->seen = s->module->is_vmlinux;
2052 	}
2053 
2054 	buf_printf(b, "\n");
2055 	buf_printf(b, "MODULE_INFO(depends, \"");
2056 	list_for_each_entry(s, &mod->unresolved_symbols, list) {
2057 		const char *p;
2058 		if (!s->module)
2059 			continue;
2060 
2061 		if (s->module->seen)
2062 			continue;
2063 
2064 		s->module->seen = true;
2065 		p = strrchr(s->module->name, '/');
2066 		if (p)
2067 			p++;
2068 		else
2069 			p = s->module->name;
2070 		buf_printf(b, "%s%s", first ? "" : ",", p);
2071 		first = 0;
2072 	}
2073 	buf_printf(b, "\");\n");
2074 }
2075 
add_srcversion(struct buffer * b,struct module * mod)2076 static void add_srcversion(struct buffer *b, struct module *mod)
2077 {
2078 	if (mod->srcversion[0]) {
2079 		buf_printf(b, "\n");
2080 		buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n",
2081 			   mod->srcversion);
2082 	}
2083 }
2084 
write_buf(struct buffer * b,const char * fname)2085 static void write_buf(struct buffer *b, const char *fname)
2086 {
2087 	FILE *file;
2088 
2089 	if (error_occurred)
2090 		return;
2091 
2092 	file = fopen(fname, "w");
2093 	if (!file) {
2094 		perror(fname);
2095 		exit(1);
2096 	}
2097 	if (fwrite(b->p, 1, b->pos, file) != b->pos) {
2098 		perror(fname);
2099 		exit(1);
2100 	}
2101 	if (fclose(file) != 0) {
2102 		perror(fname);
2103 		exit(1);
2104 	}
2105 }
2106 
write_if_changed(struct buffer * b,const char * fname)2107 static void write_if_changed(struct buffer *b, const char *fname)
2108 {
2109 	char *tmp;
2110 	FILE *file;
2111 	struct stat st;
2112 
2113 	file = fopen(fname, "r");
2114 	if (!file)
2115 		goto write;
2116 
2117 	if (fstat(fileno(file), &st) < 0)
2118 		goto close_write;
2119 
2120 	if (st.st_size != b->pos)
2121 		goto close_write;
2122 
2123 	tmp = NOFAIL(malloc(b->pos));
2124 	if (fread(tmp, 1, b->pos, file) != b->pos)
2125 		goto free_write;
2126 
2127 	if (memcmp(tmp, b->p, b->pos) != 0)
2128 		goto free_write;
2129 
2130 	free(tmp);
2131 	fclose(file);
2132 	return;
2133 
2134  free_write:
2135 	free(tmp);
2136  close_write:
2137 	fclose(file);
2138  write:
2139 	write_buf(b, fname);
2140 }
2141 
write_vmlinux_export_c_file(struct module * mod)2142 static void write_vmlinux_export_c_file(struct module *mod)
2143 {
2144 	struct buffer buf = { };
2145 
2146 	buf_printf(&buf,
2147 		   "#include <linux/export-internal.h>\n");
2148 
2149 	add_exported_symbols(&buf, mod);
2150 	write_if_changed(&buf, ".vmlinux.export.c");
2151 	free(buf.p);
2152 }
2153 
2154 /* do sanity checks, and generate *.mod.c file */
write_mod_c_file(struct module * mod)2155 static void write_mod_c_file(struct module *mod)
2156 {
2157 	struct buffer buf = { };
2158 	char fname[PATH_MAX];
2159 	int ret;
2160 
2161 	check_modname_len(mod);
2162 	check_exports(mod);
2163 
2164 	add_header(&buf, mod);
2165 	add_exported_symbols(&buf, mod);
2166 	add_versions(&buf, mod);
2167 	add_depends(&buf, mod);
2168 	add_moddevtable(&buf, mod);
2169 	add_srcversion(&buf, mod);
2170 
2171 	ret = snprintf(fname, sizeof(fname), "%s.mod.c", mod->name);
2172 	if (ret >= sizeof(fname)) {
2173 		error("%s: too long path was truncated\n", fname);
2174 		goto free;
2175 	}
2176 
2177 	write_if_changed(&buf, fname);
2178 
2179 free:
2180 	free(buf.p);
2181 }
2182 
2183 /* parse Module.symvers file. line format:
2184  * 0x12345678<tab>symbol<tab>module<tab>export<tab>namespace
2185  **/
read_dump(const char * fname)2186 static void read_dump(const char *fname)
2187 {
2188 	char *buf, *pos, *line;
2189 
2190 	buf = read_text_file(fname);
2191 	if (!buf)
2192 		/* No symbol versions, silently ignore */
2193 		return;
2194 
2195 	pos = buf;
2196 
2197 	while ((line = get_line(&pos))) {
2198 		char *symname, *namespace, *modname, *d, *export;
2199 		unsigned int crc;
2200 		struct module *mod;
2201 		struct symbol *s;
2202 		bool gpl_only;
2203 
2204 		if (!(symname = strchr(line, '\t')))
2205 			goto fail;
2206 		*symname++ = '\0';
2207 		if (!(modname = strchr(symname, '\t')))
2208 			goto fail;
2209 		*modname++ = '\0';
2210 		if (!(export = strchr(modname, '\t')))
2211 			goto fail;
2212 		*export++ = '\0';
2213 		if (!(namespace = strchr(export, '\t')))
2214 			goto fail;
2215 		*namespace++ = '\0';
2216 
2217 		crc = strtoul(line, &d, 16);
2218 		if (*symname == '\0' || *modname == '\0' || *d != '\0')
2219 			goto fail;
2220 
2221 		if (!strcmp(export, "EXPORT_SYMBOL_GPL")) {
2222 			gpl_only = true;
2223 		} else if (!strcmp(export, "EXPORT_SYMBOL")) {
2224 			gpl_only = false;
2225 		} else {
2226 			error("%s: unknown license %s. skip", symname, export);
2227 			continue;
2228 		}
2229 
2230 		mod = find_module(modname);
2231 		if (!mod) {
2232 			mod = new_module(modname, strlen(modname));
2233 			mod->from_dump = true;
2234 		}
2235 		s = sym_add_exported(symname, mod, gpl_only);
2236 		sym_set_crc(s, crc);
2237 		sym_update_namespace(symname, namespace);
2238 	}
2239 	free(buf);
2240 	return;
2241 fail:
2242 	free(buf);
2243 	fatal("parse error in symbol dump file\n");
2244 }
2245 
write_dump(const char * fname)2246 static void write_dump(const char *fname)
2247 {
2248 	struct buffer buf = { };
2249 	struct module *mod;
2250 	struct symbol *sym;
2251 
2252 	list_for_each_entry(mod, &modules, list) {
2253 		if (mod->from_dump)
2254 			continue;
2255 		list_for_each_entry(sym, &mod->exported_symbols, list) {
2256 			buf_printf(&buf, "0x%08x\t%s\t%s\tEXPORT_SYMBOL%s\t%s\n",
2257 				   sym->crc, sym->name, mod->name,
2258 				   sym->is_gpl_only ? "_GPL" : "",
2259 				   sym->namespace ?: "");
2260 		}
2261 	}
2262 	write_buf(&buf, fname);
2263 	free(buf.p);
2264 }
2265 
write_namespace_deps_files(const char * fname)2266 static void write_namespace_deps_files(const char *fname)
2267 {
2268 	struct module *mod;
2269 	struct namespace_list *ns;
2270 	struct buffer ns_deps_buf = {};
2271 
2272 	list_for_each_entry(mod, &modules, list) {
2273 
2274 		if (mod->from_dump || list_empty(&mod->missing_namespaces))
2275 			continue;
2276 
2277 		buf_printf(&ns_deps_buf, "%s.ko:", mod->name);
2278 
2279 		list_for_each_entry(ns, &mod->missing_namespaces, list)
2280 			buf_printf(&ns_deps_buf, " %s", ns->namespace);
2281 
2282 		buf_printf(&ns_deps_buf, "\n");
2283 	}
2284 
2285 	write_if_changed(&ns_deps_buf, fname);
2286 	free(ns_deps_buf.p);
2287 }
2288 
2289 struct dump_list {
2290 	struct list_head list;
2291 	const char *file;
2292 };
2293 
main(int argc,char ** argv)2294 int main(int argc, char **argv)
2295 {
2296 	struct module *mod;
2297 	char *missing_namespace_deps = NULL;
2298 	char *dump_write = NULL, *files_source = NULL;
2299 	int opt;
2300 	LIST_HEAD(dump_lists);
2301 	struct dump_list *dl, *dl2;
2302 
2303 	while ((opt = getopt(argc, argv, "ei:mnT:o:aWwENd:v:")) != -1) {
2304 		switch (opt) {
2305 		case 'e':
2306 			external_module = true;
2307 			break;
2308 		case 'i':
2309 			dl = NOFAIL(malloc(sizeof(*dl)));
2310 			dl->file = optarg;
2311 			list_add_tail(&dl->list, &dump_lists);
2312 			break;
2313 		case 'm':
2314 			modversions = true;
2315 			break;
2316 		case 'n':
2317 			ignore_missing_files = true;
2318 			break;
2319 		case 'o':
2320 			dump_write = optarg;
2321 			break;
2322 		case 'a':
2323 			all_versions = true;
2324 			break;
2325 		case 'T':
2326 			files_source = optarg;
2327 			break;
2328 		case 'W':
2329 			extra_warn = true;
2330 			break;
2331 		case 'w':
2332 			warn_unresolved = true;
2333 			break;
2334 		case 'E':
2335 			sec_mismatch_warn_only = false;
2336 			break;
2337 		case 'N':
2338 			allow_missing_ns_imports = true;
2339 			break;
2340 		case 'd':
2341 			missing_namespace_deps = optarg;
2342 			break;
2343 		case 'v':
2344 			strncpy(module_scmversion, optarg, sizeof(module_scmversion) - 1);
2345 			break;
2346 		default:
2347 			exit(1);
2348 		}
2349 	}
2350 
2351 	list_for_each_entry_safe(dl, dl2, &dump_lists, list) {
2352 		read_dump(dl->file);
2353 		list_del(&dl->list);
2354 		free(dl);
2355 	}
2356 
2357 	while (optind < argc)
2358 		read_symbols(argv[optind++]);
2359 
2360 	if (files_source)
2361 		read_symbols_from_files(files_source);
2362 
2363 	list_for_each_entry(mod, &modules, list) {
2364 		if (mod->from_dump)
2365 			continue;
2366 
2367 		if (mod->is_vmlinux)
2368 			write_vmlinux_export_c_file(mod);
2369 		else
2370 			write_mod_c_file(mod);
2371 	}
2372 
2373 	if (missing_namespace_deps)
2374 		write_namespace_deps_files(missing_namespace_deps);
2375 
2376 	if (dump_write)
2377 		write_dump(dump_write);
2378 	if (sec_mismatch_count && !sec_mismatch_warn_only)
2379 		error("Section mismatches detected.\n"
2380 		      "Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n");
2381 
2382 	if (nr_unresolved > MAX_UNRESOLVED_REPORTS)
2383 		warn("suppressed %u unresolved symbol warnings because there were too many)\n",
2384 		     nr_unresolved - MAX_UNRESOLVED_REPORTS);
2385 
2386 	return error_occurred ? 1 : 0;
2387 }
2388