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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#include <asm/cacheflush.h>
32
33/**
34 * struct klp_ops - structure for tracking registered ftrace ops structs
35 *
36 * A single ftrace_ops is shared between all enabled replacement functions
37 * (klp_func structs) which have the same old_addr. This allows the switch
38 * between function versions to happen instantaneously by updating the klp_ops
39 * struct's func_stack list. The winner is the klp_func at the top of the
40 * func_stack (front of the list).
41 *
42 * @node: node for the global klp_ops list
43 * @func_stack: list head for the stack of klp_func's (active func is on top)
44 * @fops: registered ftrace ops struct
45 */
46struct klp_ops {
47 struct list_head node;
48 struct list_head func_stack;
49 struct ftrace_ops fops;
50};
51
52/*
53 * The klp_mutex protects the global lists and state transitions of any
54 * structure reachable from them. References to any structure must be obtained
55 * under mutex protection (except in klp_ftrace_handler(), which uses RCU to
56 * ensure it gets consistent data).
57 */
58static DEFINE_MUTEX(klp_mutex);
59
60static LIST_HEAD(klp_patches);
61static LIST_HEAD(klp_ops);
62
63static struct kobject *klp_root_kobj;
64
65static struct klp_ops *klp_find_ops(unsigned long old_addr)
66{
67 struct klp_ops *ops;
68 struct klp_func *func;
69
70 list_for_each_entry(ops, &klp_ops, node) {
71 func = list_first_entry(&ops->func_stack, struct klp_func,
72 stack_node);
73 if (func->old_addr == old_addr)
74 return ops;
75 }
76
77 return NULL;
78}
79
80static bool klp_is_module(struct klp_object *obj)
81{
82 return obj->name;
83}
84
85static bool klp_is_object_loaded(struct klp_object *obj)
86{
87 return !obj->name || obj->mod;
88}
89
90/* sets obj->mod if object is not vmlinux and module is found */
91static void klp_find_object_module(struct klp_object *obj)
92{
93 struct module *mod;
94
95 if (!klp_is_module(obj))
96 return;
97
98 mutex_lock(&module_mutex);
99 /*
100 * We do not want to block removal of patched modules and therefore
101 * we do not take a reference here. The patches are removed by
102 * klp_module_going() instead.
103 */
104 mod = find_module(obj->name);
105 /*
106 * Do not mess work of klp_module_coming() and klp_module_going().
107 * Note that the patch might still be needed before klp_module_going()
108 * is called. Module functions can be called even in the GOING state
109 * until mod->exit() finishes. This is especially important for
110 * patches that modify semantic of the functions.
111 */
112 if (mod && mod->klp_alive)
113 obj->mod = mod;
114
115 mutex_unlock(&module_mutex);
116}
117
118/* klp_mutex must be held by caller */
119static bool klp_is_patch_registered(struct klp_patch *patch)
120{
121 struct klp_patch *mypatch;
122
123 list_for_each_entry(mypatch, &klp_patches, list)
124 if (mypatch == patch)
125 return true;
126
127 return false;
128}
129
130static bool klp_initialized(void)
131{
132 return !!klp_root_kobj;
133}
134
135struct klp_find_arg {
136 const char *objname;
137 const char *name;
138 unsigned long addr;
139 unsigned long count;
140 unsigned long pos;
141};
142
143static int klp_find_callback(void *data, const char *name,
144 struct module *mod, unsigned long addr)
145{
146 struct klp_find_arg *args = data;
147
148 if ((mod && !args->objname) || (!mod && args->objname))
149 return 0;
150
151 if (strcmp(args->name, name))
152 return 0;
153
154 if (args->objname && strcmp(args->objname, mod->name))
155 return 0;
156
157 args->addr = addr;
158 args->count++;
159
160 /*
161 * Finish the search when the symbol is found for the desired position
162 * or the position is not defined for a non-unique symbol.
163 */
164 if ((args->pos && (args->count == args->pos)) ||
165 (!args->pos && (args->count > 1)))
166 return 1;
167
168 return 0;
169}
170
171static int klp_find_object_symbol(const char *objname, const char *name,
172 unsigned long sympos, unsigned long *addr)
173{
174 struct klp_find_arg args = {
175 .objname = objname,
176 .name = name,
177 .addr = 0,
178 .count = 0,
179 .pos = sympos,
180 };
181
182 mutex_lock(&module_mutex);
183 kallsyms_on_each_symbol(klp_find_callback, &args);
184 mutex_unlock(&module_mutex);
185
186 /*
187 * Ensure an address was found. If sympos is 0, ensure symbol is unique;
188 * otherwise ensure the symbol position count matches sympos.
189 */
190 if (args.addr == 0)
191 pr_err("symbol '%s' not found in symbol table\n", name);
192 else if (args.count > 1 && sympos == 0) {
193 pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n",
194 name, objname);
195 } else if (sympos != args.count && sympos > 0) {
196 pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n",
197 sympos, name, objname ? objname : "vmlinux");
198 } else {
199 *addr = args.addr;
200 return 0;
201 }
202
203 *addr = 0;
204 return -EINVAL;
205}
206
207/*
208 * external symbols are located outside the parent object (where the parent
209 * object is either vmlinux or the kmod being patched).
210 */
211static int klp_find_external_symbol(struct module *pmod, const char *name,
212 unsigned long *addr)
213{
214 const struct kernel_symbol *sym;
215
216 /* first, check if it's an exported symbol */
217 preempt_disable();
218 sym = find_symbol(name, NULL, NULL, true, true);
219 if (sym) {
220 *addr = sym->value;
221 preempt_enable();
222 return 0;
223 }
224 preempt_enable();
225
226 /*
227 * Check if it's in another .o within the patch module. This also
228 * checks that the external symbol is unique.
229 */
230 return klp_find_object_symbol(pmod->name, name, 0, addr);
231}
232
233static int klp_write_object_relocations(struct module *pmod,
234 struct klp_object *obj)
235{
236 int ret = 0;
237 unsigned long val;
238 struct klp_reloc *reloc;
239
240 if (WARN_ON(!klp_is_object_loaded(obj)))
241 return -EINVAL;
242
243 if (WARN_ON(!obj->relocs))
244 return -EINVAL;
245
246 module_disable_ro(pmod);
247
248 for (reloc = obj->relocs; reloc->name; reloc++) {
249 /* discover the address of the referenced symbol */
250 if (reloc->external) {
251 if (reloc->sympos > 0) {
252 pr_err("non-zero sympos for external reloc symbol '%s' is not supported\n",
253 reloc->name);
254 ret = -EINVAL;
255 goto out;
256 }
257 ret = klp_find_external_symbol(pmod, reloc->name, &val);
258 } else
259 ret = klp_find_object_symbol(obj->name,
260 reloc->name,
261 reloc->sympos,
262 &val);
263 if (ret)
264 goto out;
265
266 ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc,
267 val + reloc->addend);
268 if (ret) {
269 pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n",
270 reloc->name, val, ret);
271 goto out;
272 }
273 }
274
275out:
276 module_enable_ro(pmod);
277 return ret;
278}
279
280static void notrace klp_ftrace_handler(unsigned long ip,
281 unsigned long parent_ip,
282 struct ftrace_ops *fops,
283 struct pt_regs *regs)
284{
285 struct klp_ops *ops;
286 struct klp_func *func;
287
288 ops = container_of(fops, struct klp_ops, fops);
289
290 rcu_read_lock();
291 func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
292 stack_node);
293 if (WARN_ON_ONCE(!func))
294 goto unlock;
295
296 klp_arch_set_pc(regs, (unsigned long)func->new_func);
297unlock:
298 rcu_read_unlock();
299}
300
301static void klp_disable_func(struct klp_func *func)
302{
303 struct klp_ops *ops;
304
305 if (WARN_ON(func->state != KLP_ENABLED))
306 return;
307 if (WARN_ON(!func->old_addr))
308 return;
309
310 ops = klp_find_ops(func->old_addr);
311 if (WARN_ON(!ops))
312 return;
313
314 if (list_is_singular(&ops->func_stack)) {
315 WARN_ON(unregister_ftrace_function(&ops->fops));
316 WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0));
317
318 list_del_rcu(&func->stack_node);
319 list_del(&ops->node);
320 kfree(ops);
321 } else {
322 list_del_rcu(&func->stack_node);
323 }
324
325 func->state = KLP_DISABLED;
326}
327
328static int klp_enable_func(struct klp_func *func)
329{
330 struct klp_ops *ops;
331 int ret;
332
333 if (WARN_ON(!func->old_addr))
334 return -EINVAL;
335
336 if (WARN_ON(func->state != KLP_DISABLED))
337 return -EINVAL;
338
339 ops = klp_find_ops(func->old_addr);
340 if (!ops) {
341 ops = kzalloc(sizeof(*ops), GFP_KERNEL);
342 if (!ops)
343 return -ENOMEM;
344
345 ops->fops.func = klp_ftrace_handler;
346 ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS |
347 FTRACE_OPS_FL_DYNAMIC |
348 FTRACE_OPS_FL_IPMODIFY;
349
350 list_add(&ops->node, &klp_ops);
351
352 INIT_LIST_HEAD(&ops->func_stack);
353 list_add_rcu(&func->stack_node, &ops->func_stack);
354
355 ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 0, 0);
356 if (ret) {
357 pr_err("failed to set ftrace filter for function '%s' (%d)\n",
358 func->old_name, ret);
359 goto err;
360 }
361
362 ret = register_ftrace_function(&ops->fops);
363 if (ret) {
364 pr_err("failed to register ftrace handler for function '%s' (%d)\n",
365 func->old_name, ret);
366 ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0);
367 goto err;
368 }
369
370
371 } else {
372 list_add_rcu(&func->stack_node, &ops->func_stack);
373 }
374
375 func->state = KLP_ENABLED;
376
377 return 0;
378
379err:
380 list_del_rcu(&func->stack_node);
381 list_del(&ops->node);
382 kfree(ops);
383 return ret;
384}
385
386static void klp_disable_object(struct klp_object *obj)
387{
388 struct klp_func *func;
389
390 klp_for_each_func(obj, func)
391 if (func->state == KLP_ENABLED)
392 klp_disable_func(func);
393
394 obj->state = KLP_DISABLED;
395}
396
397static int klp_enable_object(struct klp_object *obj)
398{
399 struct klp_func *func;
400 int ret;
401
402 if (WARN_ON(obj->state != KLP_DISABLED))
403 return -EINVAL;
404
405 if (WARN_ON(!klp_is_object_loaded(obj)))
406 return -EINVAL;
407
408 klp_for_each_func(obj, func) {
409 ret = klp_enable_func(func);
410 if (ret) {
411 klp_disable_object(obj);
412 return ret;
413 }
414 }
415 obj->state = KLP_ENABLED;
416
417 return 0;
418}
419
420static int __klp_disable_patch(struct klp_patch *patch)
421{
422 struct klp_object *obj;
423
424 /* enforce stacking: only the last enabled patch can be disabled */
425 if (!list_is_last(&patch->list, &klp_patches) &&
426 list_next_entry(patch, list)->state == KLP_ENABLED)
427 return -EBUSY;
428
429 pr_notice("disabling patch '%s'\n", patch->mod->name);
430
431 klp_for_each_object(patch, obj) {
432 if (obj->state == KLP_ENABLED)
433 klp_disable_object(obj);
434 }
435
436 patch->state = KLP_DISABLED;
437
438 return 0;
439}
440
441/**
442 * klp_disable_patch() - disables a registered patch
443 * @patch: The registered, enabled patch to be disabled
444 *
445 * Unregisters the patched functions from ftrace.
446 *
447 * Return: 0 on success, otherwise error
448 */
449int klp_disable_patch(struct klp_patch *patch)
450{
451 int ret;
452
453 mutex_lock(&klp_mutex);
454
455 if (!klp_is_patch_registered(patch)) {
456 ret = -EINVAL;
457 goto err;
458 }
459
460 if (patch->state == KLP_DISABLED) {
461 ret = -EINVAL;
462 goto err;
463 }
464
465 ret = __klp_disable_patch(patch);
466
467err:
468 mutex_unlock(&klp_mutex);
469 return ret;
470}
471EXPORT_SYMBOL_GPL(klp_disable_patch);
472
473static int __klp_enable_patch(struct klp_patch *patch)
474{
475 struct klp_object *obj;
476 int ret;
477
478 if (WARN_ON(patch->state != KLP_DISABLED))
479 return -EINVAL;
480
481 /* enforce stacking: only the first disabled patch can be enabled */
482 if (patch->list.prev != &klp_patches &&
483 list_prev_entry(patch, list)->state == KLP_DISABLED)
484 return -EBUSY;
485
486 pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n");
487 add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK);
488
489 pr_notice("enabling patch '%s'\n", patch->mod->name);
490
491 klp_for_each_object(patch, obj) {
492 if (!klp_is_object_loaded(obj))
493 continue;
494
495 ret = klp_enable_object(obj);
496 if (ret)
497 goto unregister;
498 }
499
500 patch->state = KLP_ENABLED;
501
502 return 0;
503
504unregister:
505 WARN_ON(__klp_disable_patch(patch));
506 return ret;
507}
508
509/**
510 * klp_enable_patch() - enables a registered patch
511 * @patch: The registered, disabled patch to be enabled
512 *
513 * Performs the needed symbol lookups and code relocations,
514 * then registers the patched functions with ftrace.
515 *
516 * Return: 0 on success, otherwise error
517 */
518int klp_enable_patch(struct klp_patch *patch)
519{
520 int ret;
521
522 mutex_lock(&klp_mutex);
523
524 if (!klp_is_patch_registered(patch)) {
525 ret = -EINVAL;
526 goto err;
527 }
528
529 ret = __klp_enable_patch(patch);
530
531err:
532 mutex_unlock(&klp_mutex);
533 return ret;
534}
535EXPORT_SYMBOL_GPL(klp_enable_patch);
536
537/*
538 * Sysfs Interface
539 *
540 * /sys/kernel/livepatch
541 * /sys/kernel/livepatch/<patch>
542 * /sys/kernel/livepatch/<patch>/enabled
543 * /sys/kernel/livepatch/<patch>/<object>
544 * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
545 */
546
547static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
548 const char *buf, size_t count)
549{
550 struct klp_patch *patch;
551 int ret;
552 unsigned long val;
553
554 ret = kstrtoul(buf, 10, &val);
555 if (ret)
556 return -EINVAL;
557
558 if (val != KLP_DISABLED && val != KLP_ENABLED)
559 return -EINVAL;
560
561 patch = container_of(kobj, struct klp_patch, kobj);
562
563 mutex_lock(&klp_mutex);
564
565 if (val == patch->state) {
566 /* already in requested state */
567 ret = -EINVAL;
568 goto err;
569 }
570
571 if (val == KLP_ENABLED) {
572 ret = __klp_enable_patch(patch);
573 if (ret)
574 goto err;
575 } else {
576 ret = __klp_disable_patch(patch);
577 if (ret)
578 goto err;
579 }
580
581 mutex_unlock(&klp_mutex);
582
583 return count;
584
585err:
586 mutex_unlock(&klp_mutex);
587 return ret;
588}
589
590static ssize_t enabled_show(struct kobject *kobj,
591 struct kobj_attribute *attr, char *buf)
592{
593 struct klp_patch *patch;
594
595 patch = container_of(kobj, struct klp_patch, kobj);
596 return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->state);
597}
598
599static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled);
600static struct attribute *klp_patch_attrs[] = {
601 &enabled_kobj_attr.attr,
602 NULL
603};
604
605static void klp_kobj_release_patch(struct kobject *kobj)
606{
607 /*
608 * Once we have a consistency model we'll need to module_put() the
609 * patch module here. See klp_register_patch() for more details.
610 */
611}
612
613static struct kobj_type klp_ktype_patch = {
614 .release = klp_kobj_release_patch,
615 .sysfs_ops = &kobj_sysfs_ops,
616 .default_attrs = klp_patch_attrs,
617};
618
619static void klp_kobj_release_object(struct kobject *kobj)
620{
621}
622
623static struct kobj_type klp_ktype_object = {
624 .release = klp_kobj_release_object,
625 .sysfs_ops = &kobj_sysfs_ops,
626};
627
628static void klp_kobj_release_func(struct kobject *kobj)
629{
630}
631
632static struct kobj_type klp_ktype_func = {
633 .release = klp_kobj_release_func,
634 .sysfs_ops = &kobj_sysfs_ops,
635};
636
637/*
638 * Free all functions' kobjects in the array up to some limit. When limit is
639 * NULL, all kobjects are freed.
640 */
641static void klp_free_funcs_limited(struct klp_object *obj,
642 struct klp_func *limit)
643{
644 struct klp_func *func;
645
646 for (func = obj->funcs; func->old_name && func != limit; func++)
647 kobject_put(&func->kobj);
648}
649
650/* Clean up when a patched object is unloaded */
651static void klp_free_object_loaded(struct klp_object *obj)
652{
653 struct klp_func *func;
654
655 obj->mod = NULL;
656
657 klp_for_each_func(obj, func)
658 func->old_addr = 0;
659}
660
661/*
662 * Free all objects' kobjects in the array up to some limit. When limit is
663 * NULL, all kobjects are freed.
664 */
665static void klp_free_objects_limited(struct klp_patch *patch,
666 struct klp_object *limit)
667{
668 struct klp_object *obj;
669
670 for (obj = patch->objs; obj->funcs && obj != limit; obj++) {
671 klp_free_funcs_limited(obj, NULL);
672 kobject_put(&obj->kobj);
673 }
674}
675
676static void klp_free_patch(struct klp_patch *patch)
677{
678 klp_free_objects_limited(patch, NULL);
679 if (!list_empty(&patch->list))
680 list_del(&patch->list);
681 kobject_put(&patch->kobj);
682}
683
684static int klp_init_func(struct klp_object *obj, struct klp_func *func)
685{
686 INIT_LIST_HEAD(&func->stack_node);
687 func->state = KLP_DISABLED;
688
689 /* The format for the sysfs directory is <function,sympos> where sympos
690 * is the nth occurrence of this symbol in kallsyms for the patched
691 * object. If the user selects 0 for old_sympos, then 1 will be used
692 * since a unique symbol will be the first occurrence.
693 */
694 return kobject_init_and_add(&func->kobj, &klp_ktype_func,
695 &obj->kobj, "%s,%lu", func->old_name,
696 func->old_sympos ? func->old_sympos : 1);
697}
698
699/* parts of the initialization that is done only when the object is loaded */
700static int klp_init_object_loaded(struct klp_patch *patch,
701 struct klp_object *obj)
702{
703 struct klp_func *func;
704 int ret;
705
706 if (obj->relocs) {
707 ret = klp_write_object_relocations(patch->mod, obj);
708 if (ret)
709 return ret;
710 }
711
712 klp_for_each_func(obj, func) {
713 ret = klp_find_object_symbol(obj->name, func->old_name,
714 func->old_sympos,
715 &func->old_addr);
716 if (ret)
717 return ret;
718 }
719
720 return 0;
721}
722
723static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
724{
725 struct klp_func *func;
726 int ret;
727 const char *name;
728
729 if (!obj->funcs)
730 return -EINVAL;
731
732 obj->state = KLP_DISABLED;
733 obj->mod = NULL;
734
735 klp_find_object_module(obj);
736
737 name = klp_is_module(obj) ? obj->name : "vmlinux";
738 ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object,
739 &patch->kobj, "%s", name);
740 if (ret)
741 return ret;
742
743 klp_for_each_func(obj, func) {
744 ret = klp_init_func(obj, func);
745 if (ret)
746 goto free;
747 }
748
749 if (klp_is_object_loaded(obj)) {
750 ret = klp_init_object_loaded(patch, obj);
751 if (ret)
752 goto free;
753 }
754
755 return 0;
756
757free:
758 klp_free_funcs_limited(obj, func);
759 kobject_put(&obj->kobj);
760 return ret;
761}
762
763static int klp_init_patch(struct klp_patch *patch)
764{
765 struct klp_object *obj;
766 int ret;
767
768 if (!patch->objs)
769 return -EINVAL;
770
771 mutex_lock(&klp_mutex);
772
773 patch->state = KLP_DISABLED;
774
775 ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch,
776 klp_root_kobj, "%s", patch->mod->name);
777 if (ret)
778 goto unlock;
779
780 klp_for_each_object(patch, obj) {
781 ret = klp_init_object(patch, obj);
782 if (ret)
783 goto free;
784 }
785
786 list_add_tail(&patch->list, &klp_patches);
787
788 mutex_unlock(&klp_mutex);
789
790 return 0;
791
792free:
793 klp_free_objects_limited(patch, obj);
794 kobject_put(&patch->kobj);
795unlock:
796 mutex_unlock(&klp_mutex);
797 return ret;
798}
799
800/**
801 * klp_unregister_patch() - unregisters a patch
802 * @patch: Disabled patch to be unregistered
803 *
804 * Frees the data structures and removes the sysfs interface.
805 *
806 * Return: 0 on success, otherwise error
807 */
808int klp_unregister_patch(struct klp_patch *patch)
809{
810 int ret = 0;
811
812 mutex_lock(&klp_mutex);
813
814 if (!klp_is_patch_registered(patch)) {
815 ret = -EINVAL;
816 goto out;
817 }
818
819 if (patch->state == KLP_ENABLED) {
820 ret = -EBUSY;
821 goto out;
822 }
823
824 klp_free_patch(patch);
825
826out:
827 mutex_unlock(&klp_mutex);
828 return ret;
829}
830EXPORT_SYMBOL_GPL(klp_unregister_patch);
831
832/**
833 * klp_register_patch() - registers a patch
834 * @patch: Patch to be registered
835 *
836 * Initializes the data structure associated with the patch and
837 * creates the sysfs interface.
838 *
839 * Return: 0 on success, otherwise error
840 */
841int klp_register_patch(struct klp_patch *patch)
842{
843 int ret;
844
845 if (!klp_initialized())
846 return -ENODEV;
847
848 if (!patch || !patch->mod)
849 return -EINVAL;
850
851 /*
852 * A reference is taken on the patch module to prevent it from being
853 * unloaded. Right now, we don't allow patch modules to unload since
854 * there is currently no method to determine if a thread is still
855 * running in the patched code contained in the patch module once
856 * the ftrace registration is successful.
857 */
858 if (!try_module_get(patch->mod))
859 return -ENODEV;
860
861 ret = klp_init_patch(patch);
862 if (ret)
863 module_put(patch->mod);
864
865 return ret;
866}
867EXPORT_SYMBOL_GPL(klp_register_patch);
868
869int klp_module_coming(struct module *mod)
870{
871 int ret;
872 struct klp_patch *patch;
873 struct klp_object *obj;
874
875 if (WARN_ON(mod->state != MODULE_STATE_COMING))
876 return -EINVAL;
877
878 mutex_lock(&klp_mutex);
879 /*
880 * Each module has to know that klp_module_coming()
881 * has been called. We never know what module will
882 * get patched by a new patch.
883 */
884 mod->klp_alive = true;
885
886 list_for_each_entry(patch, &klp_patches, list) {
887 klp_for_each_object(patch, obj) {
888 if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
889 continue;
890
891 obj->mod = mod;
892
893 ret = klp_init_object_loaded(patch, obj);
894 if (ret) {
895 pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
896 patch->mod->name, obj->mod->name, ret);
897 goto err;
898 }
899
900 if (patch->state == KLP_DISABLED)
901 break;
902
903 pr_notice("applying patch '%s' to loading module '%s'\n",
904 patch->mod->name, obj->mod->name);
905
906 ret = klp_enable_object(obj);
907 if (ret) {
908 pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
909 patch->mod->name, obj->mod->name, ret);
910 goto err;
911 }
912
913 break;
914 }
915 }
916
917 mutex_unlock(&klp_mutex);
918
919 return 0;
920
921err:
922 /*
923 * If a patch is unsuccessfully applied, return
924 * error to the module loader.
925 */
926 pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
927 patch->mod->name, obj->mod->name, obj->mod->name);
928 mod->klp_alive = false;
929 klp_free_object_loaded(obj);
930 mutex_unlock(&klp_mutex);
931
932 return ret;
933}
934
935void klp_module_going(struct module *mod)
936{
937 struct klp_patch *patch;
938 struct klp_object *obj;
939
940 if (WARN_ON(mod->state != MODULE_STATE_GOING &&
941 mod->state != MODULE_STATE_COMING))
942 return;
943
944 mutex_lock(&klp_mutex);
945 /*
946 * Each module has to know that klp_module_going()
947 * has been called. We never know what module will
948 * get patched by a new patch.
949 */
950 mod->klp_alive = false;
951
952 list_for_each_entry(patch, &klp_patches, list) {
953 klp_for_each_object(patch, obj) {
954 if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
955 continue;
956
957 if (patch->state != KLP_DISABLED) {
958 pr_notice("reverting patch '%s' on unloading module '%s'\n",
959 patch->mod->name, obj->mod->name);
960 klp_disable_object(obj);
961 }
962
963 klp_free_object_loaded(obj);
964 break;
965 }
966 }
967
968 mutex_unlock(&klp_mutex);
969}
970
971static int __init klp_init(void)
972{
973 int ret;
974
975 ret = klp_check_compiler_support();
976 if (ret) {
977 pr_info("Your compiler is too old; turning off.\n");
978 return -EINVAL;
979 }
980
981 klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj);
982 if (!klp_root_kobj)
983 return -ENOMEM;
984
985 return 0;
986}
987
988module_init(klp_init);