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b700e7f0 SJ |
1 | /* |
2 | * core.c - Kernel Live Patching Core | |
3 | * | |
4 | * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> | |
5 | * Copyright (C) 2014 SUSE | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version 2 | |
10 | * of the License, or (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, see <http://www.gnu.org/licenses/>. | |
19 | */ | |
20 | ||
21 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
22 | ||
23 | #include <linux/module.h> | |
24 | #include <linux/kernel.h> | |
25 | #include <linux/mutex.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/ftrace.h> | |
28 | #include <linux/list.h> | |
29 | #include <linux/kallsyms.h> | |
30 | #include <linux/livepatch.h> | |
31 | ||
32 | /* | |
33 | * The klp_mutex protects the klp_patches list and state transitions of any | |
34 | * structure reachable from the patches list. References to any structure must | |
35 | * be obtained under mutex protection. | |
36 | */ | |
37 | ||
38 | static DEFINE_MUTEX(klp_mutex); | |
39 | static LIST_HEAD(klp_patches); | |
40 | ||
41 | static struct kobject *klp_root_kobj; | |
42 | ||
43 | static bool klp_is_module(struct klp_object *obj) | |
44 | { | |
45 | return obj->name; | |
46 | } | |
47 | ||
48 | static bool klp_is_object_loaded(struct klp_object *obj) | |
49 | { | |
50 | return !obj->name || obj->mod; | |
51 | } | |
52 | ||
53 | /* sets obj->mod if object is not vmlinux and module is found */ | |
54 | static void klp_find_object_module(struct klp_object *obj) | |
55 | { | |
56 | if (!klp_is_module(obj)) | |
57 | return; | |
58 | ||
59 | mutex_lock(&module_mutex); | |
60 | /* | |
61 | * We don't need to take a reference on the module here because we have | |
62 | * the klp_mutex, which is also taken by the module notifier. This | |
63 | * prevents any module from unloading until we release the klp_mutex. | |
64 | */ | |
65 | obj->mod = find_module(obj->name); | |
66 | mutex_unlock(&module_mutex); | |
67 | } | |
68 | ||
69 | /* klp_mutex must be held by caller */ | |
70 | static bool klp_is_patch_registered(struct klp_patch *patch) | |
71 | { | |
72 | struct klp_patch *mypatch; | |
73 | ||
74 | list_for_each_entry(mypatch, &klp_patches, list) | |
75 | if (mypatch == patch) | |
76 | return true; | |
77 | ||
78 | return false; | |
79 | } | |
80 | ||
81 | static bool klp_initialized(void) | |
82 | { | |
83 | return klp_root_kobj; | |
84 | } | |
85 | ||
86 | struct klp_find_arg { | |
87 | const char *objname; | |
88 | const char *name; | |
89 | unsigned long addr; | |
90 | /* | |
91 | * If count == 0, the symbol was not found. If count == 1, a unique | |
92 | * match was found and addr is set. If count > 1, there is | |
93 | * unresolvable ambiguity among "count" number of symbols with the same | |
94 | * name in the same object. | |
95 | */ | |
96 | unsigned long count; | |
97 | }; | |
98 | ||
99 | static int klp_find_callback(void *data, const char *name, | |
100 | struct module *mod, unsigned long addr) | |
101 | { | |
102 | struct klp_find_arg *args = data; | |
103 | ||
104 | if ((mod && !args->objname) || (!mod && args->objname)) | |
105 | return 0; | |
106 | ||
107 | if (strcmp(args->name, name)) | |
108 | return 0; | |
109 | ||
110 | if (args->objname && strcmp(args->objname, mod->name)) | |
111 | return 0; | |
112 | ||
113 | /* | |
114 | * args->addr might be overwritten if another match is found | |
115 | * but klp_find_object_symbol() handles this and only returns the | |
116 | * addr if count == 1. | |
117 | */ | |
118 | args->addr = addr; | |
119 | args->count++; | |
120 | ||
121 | return 0; | |
122 | } | |
123 | ||
124 | static int klp_find_object_symbol(const char *objname, const char *name, | |
125 | unsigned long *addr) | |
126 | { | |
127 | struct klp_find_arg args = { | |
128 | .objname = objname, | |
129 | .name = name, | |
130 | .addr = 0, | |
131 | .count = 0 | |
132 | }; | |
133 | ||
134 | kallsyms_on_each_symbol(klp_find_callback, &args); | |
135 | ||
136 | if (args.count == 0) | |
137 | pr_err("symbol '%s' not found in symbol table\n", name); | |
138 | else if (args.count > 1) | |
139 | pr_err("unresolvable ambiguity (%lu matches) on symbol '%s' in object '%s'\n", | |
140 | args.count, name, objname); | |
141 | else { | |
142 | *addr = args.addr; | |
143 | return 0; | |
144 | } | |
145 | ||
146 | *addr = 0; | |
147 | return -EINVAL; | |
148 | } | |
149 | ||
150 | struct klp_verify_args { | |
151 | const char *name; | |
152 | const unsigned long addr; | |
153 | }; | |
154 | ||
155 | static int klp_verify_callback(void *data, const char *name, | |
156 | struct module *mod, unsigned long addr) | |
157 | { | |
158 | struct klp_verify_args *args = data; | |
159 | ||
160 | if (!mod && | |
161 | !strcmp(args->name, name) && | |
162 | args->addr == addr) | |
163 | return 1; | |
164 | ||
165 | return 0; | |
166 | } | |
167 | ||
168 | static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr) | |
169 | { | |
170 | struct klp_verify_args args = { | |
171 | .name = name, | |
172 | .addr = addr, | |
173 | }; | |
174 | ||
175 | if (kallsyms_on_each_symbol(klp_verify_callback, &args)) | |
176 | return 0; | |
177 | ||
178 | pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?", | |
179 | name, addr); | |
180 | return -EINVAL; | |
181 | } | |
182 | ||
183 | static int klp_find_verify_func_addr(struct klp_object *obj, | |
184 | struct klp_func *func) | |
185 | { | |
186 | int ret; | |
187 | ||
188 | #if defined(CONFIG_RANDOMIZE_BASE) | |
189 | /* KASLR is enabled, disregard old_addr from user */ | |
190 | func->old_addr = 0; | |
191 | #endif | |
192 | ||
193 | if (!func->old_addr || klp_is_module(obj)) | |
194 | ret = klp_find_object_symbol(obj->name, func->old_name, | |
195 | &func->old_addr); | |
196 | else | |
197 | ret = klp_verify_vmlinux_symbol(func->old_name, | |
198 | func->old_addr); | |
199 | ||
200 | return ret; | |
201 | } | |
202 | ||
203 | /* | |
204 | * external symbols are located outside the parent object (where the parent | |
205 | * object is either vmlinux or the kmod being patched). | |
206 | */ | |
207 | static int klp_find_external_symbol(struct module *pmod, const char *name, | |
208 | unsigned long *addr) | |
209 | { | |
210 | const struct kernel_symbol *sym; | |
211 | ||
212 | /* first, check if it's an exported symbol */ | |
213 | preempt_disable(); | |
214 | sym = find_symbol(name, NULL, NULL, true, true); | |
215 | preempt_enable(); | |
216 | if (sym) { | |
217 | *addr = sym->value; | |
218 | return 0; | |
219 | } | |
220 | ||
221 | /* otherwise check if it's in another .o within the patch module */ | |
222 | return klp_find_object_symbol(pmod->name, name, addr); | |
223 | } | |
224 | ||
225 | static int klp_write_object_relocations(struct module *pmod, | |
226 | struct klp_object *obj) | |
227 | { | |
228 | int ret; | |
229 | struct klp_reloc *reloc; | |
230 | ||
231 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
232 | return -EINVAL; | |
233 | ||
234 | if (WARN_ON(!obj->relocs)) | |
235 | return -EINVAL; | |
236 | ||
237 | for (reloc = obj->relocs; reloc->name; reloc++) { | |
238 | if (!klp_is_module(obj)) { | |
239 | ret = klp_verify_vmlinux_symbol(reloc->name, | |
240 | reloc->val); | |
241 | if (ret) | |
242 | return ret; | |
243 | } else { | |
244 | /* module, reloc->val needs to be discovered */ | |
245 | if (reloc->external) | |
246 | ret = klp_find_external_symbol(pmod, | |
247 | reloc->name, | |
248 | &reloc->val); | |
249 | else | |
250 | ret = klp_find_object_symbol(obj->mod->name, | |
251 | reloc->name, | |
252 | &reloc->val); | |
253 | if (ret) | |
254 | return ret; | |
255 | } | |
256 | ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc, | |
257 | reloc->val + reloc->addend); | |
258 | if (ret) { | |
259 | pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n", | |
260 | reloc->name, reloc->val, ret); | |
261 | return ret; | |
262 | } | |
263 | } | |
264 | ||
265 | return 0; | |
266 | } | |
267 | ||
268 | static void notrace klp_ftrace_handler(unsigned long ip, | |
269 | unsigned long parent_ip, | |
270 | struct ftrace_ops *ops, | |
271 | struct pt_regs *regs) | |
272 | { | |
273 | struct klp_func *func = ops->private; | |
274 | ||
b5bfc517 | 275 | klp_arch_set_pc(regs, (unsigned long)func->new_func); |
b700e7f0 SJ |
276 | } |
277 | ||
278 | static int klp_disable_func(struct klp_func *func) | |
279 | { | |
280 | int ret; | |
281 | ||
282 | if (WARN_ON(func->state != KLP_ENABLED)) | |
283 | return -EINVAL; | |
284 | ||
285 | if (WARN_ON(!func->old_addr)) | |
286 | return -EINVAL; | |
287 | ||
288 | ret = unregister_ftrace_function(func->fops); | |
289 | if (ret) { | |
290 | pr_err("failed to unregister ftrace handler for function '%s' (%d)\n", | |
291 | func->old_name, ret); | |
292 | return ret; | |
293 | } | |
294 | ||
295 | ret = ftrace_set_filter_ip(func->fops, func->old_addr, 1, 0); | |
296 | if (ret) | |
297 | pr_warn("function unregister succeeded but failed to clear the filter\n"); | |
298 | ||
299 | func->state = KLP_DISABLED; | |
300 | ||
301 | return 0; | |
302 | } | |
303 | ||
304 | static int klp_enable_func(struct klp_func *func) | |
305 | { | |
306 | int ret; | |
307 | ||
308 | if (WARN_ON(!func->old_addr)) | |
309 | return -EINVAL; | |
310 | ||
311 | if (WARN_ON(func->state != KLP_DISABLED)) | |
312 | return -EINVAL; | |
313 | ||
314 | ret = ftrace_set_filter_ip(func->fops, func->old_addr, 0, 0); | |
315 | if (ret) { | |
316 | pr_err("failed to set ftrace filter for function '%s' (%d)\n", | |
317 | func->old_name, ret); | |
318 | return ret; | |
319 | } | |
320 | ||
321 | ret = register_ftrace_function(func->fops); | |
322 | if (ret) { | |
323 | pr_err("failed to register ftrace handler for function '%s' (%d)\n", | |
324 | func->old_name, ret); | |
325 | ftrace_set_filter_ip(func->fops, func->old_addr, 1, 0); | |
326 | } else { | |
327 | func->state = KLP_ENABLED; | |
328 | } | |
329 | ||
330 | return ret; | |
331 | } | |
332 | ||
333 | static int klp_disable_object(struct klp_object *obj) | |
334 | { | |
335 | struct klp_func *func; | |
336 | int ret; | |
337 | ||
338 | for (func = obj->funcs; func->old_name; func++) { | |
339 | if (func->state != KLP_ENABLED) | |
340 | continue; | |
341 | ||
342 | ret = klp_disable_func(func); | |
343 | if (ret) | |
344 | return ret; | |
345 | } | |
346 | ||
347 | obj->state = KLP_DISABLED; | |
348 | ||
349 | return 0; | |
350 | } | |
351 | ||
352 | static int klp_enable_object(struct klp_object *obj) | |
353 | { | |
354 | struct klp_func *func; | |
355 | int ret; | |
356 | ||
357 | if (WARN_ON(obj->state != KLP_DISABLED)) | |
358 | return -EINVAL; | |
359 | ||
360 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
361 | return -EINVAL; | |
362 | ||
363 | for (func = obj->funcs; func->old_name; func++) { | |
364 | ret = klp_enable_func(func); | |
365 | if (ret) | |
366 | goto unregister; | |
367 | } | |
368 | obj->state = KLP_ENABLED; | |
369 | ||
370 | return 0; | |
371 | ||
372 | unregister: | |
373 | WARN_ON(klp_disable_object(obj)); | |
374 | return ret; | |
375 | } | |
376 | ||
377 | static int __klp_disable_patch(struct klp_patch *patch) | |
378 | { | |
379 | struct klp_object *obj; | |
380 | int ret; | |
381 | ||
382 | pr_notice("disabling patch '%s'\n", patch->mod->name); | |
383 | ||
384 | for (obj = patch->objs; obj->funcs; obj++) { | |
385 | if (obj->state != KLP_ENABLED) | |
386 | continue; | |
387 | ||
388 | ret = klp_disable_object(obj); | |
389 | if (ret) | |
390 | return ret; | |
391 | } | |
392 | ||
393 | patch->state = KLP_DISABLED; | |
394 | ||
395 | return 0; | |
396 | } | |
397 | ||
398 | /** | |
399 | * klp_disable_patch() - disables a registered patch | |
400 | * @patch: The registered, enabled patch to be disabled | |
401 | * | |
402 | * Unregisters the patched functions from ftrace. | |
403 | * | |
404 | * Return: 0 on success, otherwise error | |
405 | */ | |
406 | int klp_disable_patch(struct klp_patch *patch) | |
407 | { | |
408 | int ret; | |
409 | ||
410 | mutex_lock(&klp_mutex); | |
411 | ||
412 | if (!klp_is_patch_registered(patch)) { | |
413 | ret = -EINVAL; | |
414 | goto err; | |
415 | } | |
416 | ||
417 | if (patch->state == KLP_DISABLED) { | |
418 | ret = -EINVAL; | |
419 | goto err; | |
420 | } | |
421 | ||
422 | ret = __klp_disable_patch(patch); | |
423 | ||
424 | err: | |
425 | mutex_unlock(&klp_mutex); | |
426 | return ret; | |
427 | } | |
428 | EXPORT_SYMBOL_GPL(klp_disable_patch); | |
429 | ||
430 | static int __klp_enable_patch(struct klp_patch *patch) | |
431 | { | |
432 | struct klp_object *obj; | |
433 | int ret; | |
434 | ||
435 | if (WARN_ON(patch->state != KLP_DISABLED)) | |
436 | return -EINVAL; | |
437 | ||
438 | pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n"); | |
439 | add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK); | |
440 | ||
441 | pr_notice("enabling patch '%s'\n", patch->mod->name); | |
442 | ||
443 | for (obj = patch->objs; obj->funcs; obj++) { | |
444 | klp_find_object_module(obj); | |
445 | ||
446 | if (!klp_is_object_loaded(obj)) | |
447 | continue; | |
448 | ||
449 | ret = klp_enable_object(obj); | |
450 | if (ret) | |
451 | goto unregister; | |
452 | } | |
453 | ||
454 | patch->state = KLP_ENABLED; | |
455 | ||
456 | return 0; | |
457 | ||
458 | unregister: | |
459 | WARN_ON(__klp_disable_patch(patch)); | |
460 | return ret; | |
461 | } | |
462 | ||
463 | /** | |
464 | * klp_enable_patch() - enables a registered patch | |
465 | * @patch: The registered, disabled patch to be enabled | |
466 | * | |
467 | * Performs the needed symbol lookups and code relocations, | |
468 | * then registers the patched functions with ftrace. | |
469 | * | |
470 | * Return: 0 on success, otherwise error | |
471 | */ | |
472 | int klp_enable_patch(struct klp_patch *patch) | |
473 | { | |
474 | int ret; | |
475 | ||
476 | mutex_lock(&klp_mutex); | |
477 | ||
478 | if (!klp_is_patch_registered(patch)) { | |
479 | ret = -EINVAL; | |
480 | goto err; | |
481 | } | |
482 | ||
483 | ret = __klp_enable_patch(patch); | |
484 | ||
485 | err: | |
486 | mutex_unlock(&klp_mutex); | |
487 | return ret; | |
488 | } | |
489 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
490 | ||
491 | /* | |
492 | * Sysfs Interface | |
493 | * | |
494 | * /sys/kernel/livepatch | |
495 | * /sys/kernel/livepatch/<patch> | |
496 | * /sys/kernel/livepatch/<patch>/enabled | |
497 | * /sys/kernel/livepatch/<patch>/<object> | |
498 | * /sys/kernel/livepatch/<patch>/<object>/<func> | |
499 | */ | |
500 | ||
501 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
502 | const char *buf, size_t count) | |
503 | { | |
504 | struct klp_patch *patch; | |
505 | int ret; | |
506 | unsigned long val; | |
507 | ||
508 | ret = kstrtoul(buf, 10, &val); | |
509 | if (ret) | |
510 | return -EINVAL; | |
511 | ||
512 | if (val != KLP_DISABLED && val != KLP_ENABLED) | |
513 | return -EINVAL; | |
514 | ||
515 | patch = container_of(kobj, struct klp_patch, kobj); | |
516 | ||
517 | mutex_lock(&klp_mutex); | |
518 | ||
519 | if (val == patch->state) { | |
520 | /* already in requested state */ | |
521 | ret = -EINVAL; | |
522 | goto err; | |
523 | } | |
524 | ||
525 | if (val == KLP_ENABLED) { | |
526 | ret = __klp_enable_patch(patch); | |
527 | if (ret) | |
528 | goto err; | |
529 | } else { | |
530 | ret = __klp_disable_patch(patch); | |
531 | if (ret) | |
532 | goto err; | |
533 | } | |
534 | ||
535 | mutex_unlock(&klp_mutex); | |
536 | ||
537 | return count; | |
538 | ||
539 | err: | |
540 | mutex_unlock(&klp_mutex); | |
541 | return ret; | |
542 | } | |
543 | ||
544 | static ssize_t enabled_show(struct kobject *kobj, | |
545 | struct kobj_attribute *attr, char *buf) | |
546 | { | |
547 | struct klp_patch *patch; | |
548 | ||
549 | patch = container_of(kobj, struct klp_patch, kobj); | |
550 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->state); | |
551 | } | |
552 | ||
553 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); | |
554 | static struct attribute *klp_patch_attrs[] = { | |
555 | &enabled_kobj_attr.attr, | |
556 | NULL | |
557 | }; | |
558 | ||
559 | static void klp_kobj_release_patch(struct kobject *kobj) | |
560 | { | |
561 | /* | |
562 | * Once we have a consistency model we'll need to module_put() the | |
563 | * patch module here. See klp_register_patch() for more details. | |
564 | */ | |
565 | } | |
566 | ||
567 | static struct kobj_type klp_ktype_patch = { | |
568 | .release = klp_kobj_release_patch, | |
569 | .sysfs_ops = &kobj_sysfs_ops, | |
570 | .default_attrs = klp_patch_attrs, | |
571 | }; | |
572 | ||
573 | static void klp_kobj_release_func(struct kobject *kobj) | |
574 | { | |
575 | struct klp_func *func; | |
576 | ||
577 | func = container_of(kobj, struct klp_func, kobj); | |
578 | kfree(func->fops); | |
579 | } | |
580 | ||
581 | static struct kobj_type klp_ktype_func = { | |
582 | .release = klp_kobj_release_func, | |
583 | .sysfs_ops = &kobj_sysfs_ops, | |
584 | }; | |
585 | ||
586 | /* | |
587 | * Free all functions' kobjects in the array up to some limit. When limit is | |
588 | * NULL, all kobjects are freed. | |
589 | */ | |
590 | static void klp_free_funcs_limited(struct klp_object *obj, | |
591 | struct klp_func *limit) | |
592 | { | |
593 | struct klp_func *func; | |
594 | ||
595 | for (func = obj->funcs; func->old_name && func != limit; func++) | |
596 | kobject_put(&func->kobj); | |
597 | } | |
598 | ||
599 | /* Clean up when a patched object is unloaded */ | |
600 | static void klp_free_object_loaded(struct klp_object *obj) | |
601 | { | |
602 | struct klp_func *func; | |
603 | ||
604 | obj->mod = NULL; | |
605 | ||
606 | for (func = obj->funcs; func->old_name; func++) | |
607 | func->old_addr = 0; | |
608 | } | |
609 | ||
610 | /* | |
611 | * Free all objects' kobjects in the array up to some limit. When limit is | |
612 | * NULL, all kobjects are freed. | |
613 | */ | |
614 | static void klp_free_objects_limited(struct klp_patch *patch, | |
615 | struct klp_object *limit) | |
616 | { | |
617 | struct klp_object *obj; | |
618 | ||
619 | for (obj = patch->objs; obj->funcs && obj != limit; obj++) { | |
620 | klp_free_funcs_limited(obj, NULL); | |
621 | kobject_put(obj->kobj); | |
622 | } | |
623 | } | |
624 | ||
625 | static void klp_free_patch(struct klp_patch *patch) | |
626 | { | |
627 | klp_free_objects_limited(patch, NULL); | |
628 | if (!list_empty(&patch->list)) | |
629 | list_del(&patch->list); | |
630 | kobject_put(&patch->kobj); | |
631 | } | |
632 | ||
633 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
634 | { | |
635 | struct ftrace_ops *ops; | |
636 | int ret; | |
637 | ||
638 | ops = kzalloc(sizeof(*ops), GFP_KERNEL); | |
639 | if (!ops) | |
640 | return -ENOMEM; | |
641 | ||
642 | ops->private = func; | |
643 | ops->func = klp_ftrace_handler; | |
33e8612f JP |
644 | ops->flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_DYNAMIC | |
645 | FTRACE_OPS_FL_IPMODIFY; | |
b700e7f0 SJ |
646 | func->fops = ops; |
647 | func->state = KLP_DISABLED; | |
648 | ||
649 | ret = kobject_init_and_add(&func->kobj, &klp_ktype_func, | |
650 | obj->kobj, func->old_name); | |
651 | if (ret) { | |
652 | kfree(func->fops); | |
653 | return ret; | |
654 | } | |
655 | ||
656 | return 0; | |
657 | } | |
658 | ||
659 | /* parts of the initialization that is done only when the object is loaded */ | |
660 | static int klp_init_object_loaded(struct klp_patch *patch, | |
661 | struct klp_object *obj) | |
662 | { | |
663 | struct klp_func *func; | |
664 | int ret; | |
665 | ||
666 | if (obj->relocs) { | |
667 | ret = klp_write_object_relocations(patch->mod, obj); | |
668 | if (ret) | |
669 | return ret; | |
670 | } | |
671 | ||
672 | for (func = obj->funcs; func->old_name; func++) { | |
673 | ret = klp_find_verify_func_addr(obj, func); | |
674 | if (ret) | |
675 | return ret; | |
676 | } | |
677 | ||
678 | return 0; | |
679 | } | |
680 | ||
681 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
682 | { | |
683 | struct klp_func *func; | |
684 | int ret; | |
685 | const char *name; | |
686 | ||
687 | if (!obj->funcs) | |
688 | return -EINVAL; | |
689 | ||
690 | obj->state = KLP_DISABLED; | |
691 | ||
692 | klp_find_object_module(obj); | |
693 | ||
694 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
695 | obj->kobj = kobject_create_and_add(name, &patch->kobj); | |
696 | if (!obj->kobj) | |
697 | return -ENOMEM; | |
698 | ||
699 | for (func = obj->funcs; func->old_name; func++) { | |
700 | ret = klp_init_func(obj, func); | |
701 | if (ret) | |
702 | goto free; | |
703 | } | |
704 | ||
705 | if (klp_is_object_loaded(obj)) { | |
706 | ret = klp_init_object_loaded(patch, obj); | |
707 | if (ret) | |
708 | goto free; | |
709 | } | |
710 | ||
711 | return 0; | |
712 | ||
713 | free: | |
714 | klp_free_funcs_limited(obj, func); | |
715 | kobject_put(obj->kobj); | |
716 | return ret; | |
717 | } | |
718 | ||
719 | static int klp_init_patch(struct klp_patch *patch) | |
720 | { | |
721 | struct klp_object *obj; | |
722 | int ret; | |
723 | ||
724 | if (!patch->objs) | |
725 | return -EINVAL; | |
726 | ||
727 | mutex_lock(&klp_mutex); | |
728 | ||
729 | patch->state = KLP_DISABLED; | |
730 | ||
731 | ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, | |
732 | klp_root_kobj, patch->mod->name); | |
733 | if (ret) | |
734 | goto unlock; | |
735 | ||
736 | for (obj = patch->objs; obj->funcs; obj++) { | |
737 | ret = klp_init_object(patch, obj); | |
738 | if (ret) | |
739 | goto free; | |
740 | } | |
741 | ||
99590ba5 | 742 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
743 | |
744 | mutex_unlock(&klp_mutex); | |
745 | ||
746 | return 0; | |
747 | ||
748 | free: | |
749 | klp_free_objects_limited(patch, obj); | |
750 | kobject_put(&patch->kobj); | |
751 | unlock: | |
752 | mutex_unlock(&klp_mutex); | |
753 | return ret; | |
754 | } | |
755 | ||
756 | /** | |
757 | * klp_unregister_patch() - unregisters a patch | |
758 | * @patch: Disabled patch to be unregistered | |
759 | * | |
760 | * Frees the data structures and removes the sysfs interface. | |
761 | * | |
762 | * Return: 0 on success, otherwise error | |
763 | */ | |
764 | int klp_unregister_patch(struct klp_patch *patch) | |
765 | { | |
766 | int ret = 0; | |
767 | ||
768 | mutex_lock(&klp_mutex); | |
769 | ||
770 | if (!klp_is_patch_registered(patch)) { | |
771 | ret = -EINVAL; | |
772 | goto out; | |
773 | } | |
774 | ||
775 | if (patch->state == KLP_ENABLED) { | |
776 | ret = -EBUSY; | |
777 | goto out; | |
778 | } | |
779 | ||
780 | klp_free_patch(patch); | |
781 | ||
782 | out: | |
783 | mutex_unlock(&klp_mutex); | |
784 | return ret; | |
785 | } | |
786 | EXPORT_SYMBOL_GPL(klp_unregister_patch); | |
787 | ||
788 | /** | |
789 | * klp_register_patch() - registers a patch | |
790 | * @patch: Patch to be registered | |
791 | * | |
792 | * Initializes the data structure associated with the patch and | |
793 | * creates the sysfs interface. | |
794 | * | |
795 | * Return: 0 on success, otherwise error | |
796 | */ | |
797 | int klp_register_patch(struct klp_patch *patch) | |
798 | { | |
799 | int ret; | |
800 | ||
801 | if (!klp_initialized()) | |
802 | return -ENODEV; | |
803 | ||
804 | if (!patch || !patch->mod) | |
805 | return -EINVAL; | |
806 | ||
807 | /* | |
808 | * A reference is taken on the patch module to prevent it from being | |
809 | * unloaded. Right now, we don't allow patch modules to unload since | |
810 | * there is currently no method to determine if a thread is still | |
811 | * running in the patched code contained in the patch module once | |
812 | * the ftrace registration is successful. | |
813 | */ | |
814 | if (!try_module_get(patch->mod)) | |
815 | return -ENODEV; | |
816 | ||
817 | ret = klp_init_patch(patch); | |
818 | if (ret) | |
819 | module_put(patch->mod); | |
820 | ||
821 | return ret; | |
822 | } | |
823 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
824 | ||
825 | static void klp_module_notify_coming(struct klp_patch *patch, | |
826 | struct klp_object *obj) | |
827 | { | |
828 | struct module *pmod = patch->mod; | |
829 | struct module *mod = obj->mod; | |
830 | int ret; | |
831 | ||
832 | ret = klp_init_object_loaded(patch, obj); | |
833 | if (ret) | |
834 | goto err; | |
835 | ||
836 | if (patch->state == KLP_DISABLED) | |
837 | return; | |
838 | ||
839 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
840 | pmod->name, mod->name); | |
841 | ||
842 | ret = klp_enable_object(obj); | |
843 | if (!ret) | |
844 | return; | |
845 | ||
846 | err: | |
847 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
848 | pmod->name, mod->name, ret); | |
849 | } | |
850 | ||
851 | static void klp_module_notify_going(struct klp_patch *patch, | |
852 | struct klp_object *obj) | |
853 | { | |
854 | struct module *pmod = patch->mod; | |
855 | struct module *mod = obj->mod; | |
856 | int ret; | |
857 | ||
858 | if (patch->state == KLP_DISABLED) | |
859 | goto disabled; | |
860 | ||
861 | pr_notice("reverting patch '%s' on unloading module '%s'\n", | |
862 | pmod->name, mod->name); | |
863 | ||
864 | ret = klp_disable_object(obj); | |
865 | if (ret) | |
866 | pr_warn("failed to revert patch '%s' on module '%s' (%d)\n", | |
867 | pmod->name, mod->name, ret); | |
868 | ||
869 | disabled: | |
870 | klp_free_object_loaded(obj); | |
871 | } | |
872 | ||
873 | static int klp_module_notify(struct notifier_block *nb, unsigned long action, | |
874 | void *data) | |
875 | { | |
876 | struct module *mod = data; | |
877 | struct klp_patch *patch; | |
878 | struct klp_object *obj; | |
879 | ||
880 | if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING) | |
881 | return 0; | |
882 | ||
883 | mutex_lock(&klp_mutex); | |
884 | ||
885 | list_for_each_entry(patch, &klp_patches, list) { | |
886 | for (obj = patch->objs; obj->funcs; obj++) { | |
887 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
888 | continue; | |
889 | ||
890 | if (action == MODULE_STATE_COMING) { | |
891 | obj->mod = mod; | |
892 | klp_module_notify_coming(patch, obj); | |
893 | } else /* MODULE_STATE_GOING */ | |
894 | klp_module_notify_going(patch, obj); | |
895 | ||
896 | break; | |
897 | } | |
898 | } | |
899 | ||
900 | mutex_unlock(&klp_mutex); | |
901 | ||
902 | return 0; | |
903 | } | |
904 | ||
905 | static struct notifier_block klp_module_nb = { | |
906 | .notifier_call = klp_module_notify, | |
907 | .priority = INT_MIN+1, /* called late but before ftrace notifier */ | |
908 | }; | |
909 | ||
910 | static int klp_init(void) | |
911 | { | |
912 | int ret; | |
913 | ||
b9dfe0be JK |
914 | ret = klp_check_compiler_support(); |
915 | if (ret) { | |
916 | pr_info("Your compiler is too old; turning off.\n"); | |
917 | return -EINVAL; | |
918 | } | |
919 | ||
b700e7f0 SJ |
920 | ret = register_module_notifier(&klp_module_nb); |
921 | if (ret) | |
922 | return ret; | |
923 | ||
924 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); | |
925 | if (!klp_root_kobj) { | |
926 | ret = -ENOMEM; | |
927 | goto unregister; | |
928 | } | |
929 | ||
930 | return 0; | |
931 | ||
932 | unregister: | |
933 | unregister_module_notifier(&klp_module_nb); | |
934 | return ret; | |
935 | } | |
936 | ||
937 | module_init(klp_init); |