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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 | ||
3c33f5b9 JP |
32 | /** |
33 | * struct klp_ops - structure for tracking registered ftrace ops structs | |
34 | * | |
35 | * A single ftrace_ops is shared between all enabled replacement functions | |
36 | * (klp_func structs) which have the same old_addr. This allows the switch | |
37 | * between function versions to happen instantaneously by updating the klp_ops | |
38 | * struct's func_stack list. The winner is the klp_func at the top of the | |
39 | * func_stack (front of the list). | |
40 | * | |
41 | * @node: node for the global klp_ops list | |
42 | * @func_stack: list head for the stack of klp_func's (active func is on top) | |
43 | * @fops: registered ftrace ops struct | |
b700e7f0 | 44 | */ |
3c33f5b9 JP |
45 | struct klp_ops { |
46 | struct list_head node; | |
47 | struct list_head func_stack; | |
48 | struct ftrace_ops fops; | |
49 | }; | |
b700e7f0 | 50 | |
3c33f5b9 JP |
51 | /* |
52 | * The klp_mutex protects the global lists and state transitions of any | |
53 | * structure reachable from them. References to any structure must be obtained | |
54 | * under mutex protection (except in klp_ftrace_handler(), which uses RCU to | |
55 | * ensure it gets consistent data). | |
56 | */ | |
b700e7f0 | 57 | static DEFINE_MUTEX(klp_mutex); |
3c33f5b9 | 58 | |
b700e7f0 | 59 | static LIST_HEAD(klp_patches); |
3c33f5b9 | 60 | static LIST_HEAD(klp_ops); |
b700e7f0 SJ |
61 | |
62 | static struct kobject *klp_root_kobj; | |
63 | ||
3c33f5b9 JP |
64 | static struct klp_ops *klp_find_ops(unsigned long old_addr) |
65 | { | |
66 | struct klp_ops *ops; | |
67 | struct klp_func *func; | |
68 | ||
69 | list_for_each_entry(ops, &klp_ops, node) { | |
70 | func = list_first_entry(&ops->func_stack, struct klp_func, | |
71 | stack_node); | |
72 | if (func->old_addr == old_addr) | |
73 | return ops; | |
74 | } | |
75 | ||
76 | return NULL; | |
77 | } | |
78 | ||
b700e7f0 SJ |
79 | static bool klp_is_module(struct klp_object *obj) |
80 | { | |
81 | return obj->name; | |
82 | } | |
83 | ||
84 | static bool klp_is_object_loaded(struct klp_object *obj) | |
85 | { | |
86 | return !obj->name || obj->mod; | |
87 | } | |
88 | ||
89 | /* sets obj->mod if object is not vmlinux and module is found */ | |
90 | static void klp_find_object_module(struct klp_object *obj) | |
91 | { | |
8cb2c2dc PM |
92 | struct module *mod; |
93 | ||
b700e7f0 SJ |
94 | if (!klp_is_module(obj)) |
95 | return; | |
96 | ||
97 | mutex_lock(&module_mutex); | |
98 | /* | |
8cb2c2dc PM |
99 | * We do not want to block removal of patched modules and therefore |
100 | * we do not take a reference here. The patches are removed by | |
101 | * a going module handler instead. | |
102 | */ | |
103 | mod = find_module(obj->name); | |
104 | /* | |
105 | * Do not mess work of the module coming and going notifiers. | |
106 | * Note that the patch might still be needed before the going handler | |
107 | * is called. Module functions can be called even in the GOING state | |
108 | * until mod->exit() finishes. This is especially important for | |
109 | * patches that modify semantic of the functions. | |
b700e7f0 | 110 | */ |
8cb2c2dc PM |
111 | if (mod && mod->klp_alive) |
112 | obj->mod = mod; | |
113 | ||
b700e7f0 SJ |
114 | mutex_unlock(&module_mutex); |
115 | } | |
116 | ||
117 | /* klp_mutex must be held by caller */ | |
118 | static bool klp_is_patch_registered(struct klp_patch *patch) | |
119 | { | |
120 | struct klp_patch *mypatch; | |
121 | ||
122 | list_for_each_entry(mypatch, &klp_patches, list) | |
123 | if (mypatch == patch) | |
124 | return true; | |
125 | ||
126 | return false; | |
127 | } | |
128 | ||
129 | static bool klp_initialized(void) | |
130 | { | |
e76ff06a | 131 | return !!klp_root_kobj; |
b700e7f0 SJ |
132 | } |
133 | ||
134 | struct klp_find_arg { | |
135 | const char *objname; | |
136 | const char *name; | |
137 | unsigned long addr; | |
138 | /* | |
139 | * If count == 0, the symbol was not found. If count == 1, a unique | |
140 | * match was found and addr is set. If count > 1, there is | |
141 | * unresolvable ambiguity among "count" number of symbols with the same | |
142 | * name in the same object. | |
143 | */ | |
144 | unsigned long count; | |
145 | }; | |
146 | ||
147 | static int klp_find_callback(void *data, const char *name, | |
148 | struct module *mod, unsigned long addr) | |
149 | { | |
150 | struct klp_find_arg *args = data; | |
151 | ||
152 | if ((mod && !args->objname) || (!mod && args->objname)) | |
153 | return 0; | |
154 | ||
155 | if (strcmp(args->name, name)) | |
156 | return 0; | |
157 | ||
158 | if (args->objname && strcmp(args->objname, mod->name)) | |
159 | return 0; | |
160 | ||
161 | /* | |
162 | * args->addr might be overwritten if another match is found | |
163 | * but klp_find_object_symbol() handles this and only returns the | |
164 | * addr if count == 1. | |
165 | */ | |
166 | args->addr = addr; | |
167 | args->count++; | |
168 | ||
169 | return 0; | |
170 | } | |
171 | ||
172 | static int klp_find_object_symbol(const char *objname, const char *name, | |
173 | unsigned long *addr) | |
174 | { | |
175 | struct klp_find_arg args = { | |
176 | .objname = objname, | |
177 | .name = name, | |
178 | .addr = 0, | |
179 | .count = 0 | |
180 | }; | |
181 | ||
9a1bd63c | 182 | mutex_lock(&module_mutex); |
b700e7f0 | 183 | kallsyms_on_each_symbol(klp_find_callback, &args); |
9a1bd63c | 184 | mutex_unlock(&module_mutex); |
b700e7f0 SJ |
185 | |
186 | if (args.count == 0) | |
187 | pr_err("symbol '%s' not found in symbol table\n", name); | |
188 | else if (args.count > 1) | |
189 | pr_err("unresolvable ambiguity (%lu matches) on symbol '%s' in object '%s'\n", | |
190 | args.count, name, objname); | |
191 | else { | |
192 | *addr = args.addr; | |
193 | return 0; | |
194 | } | |
195 | ||
196 | *addr = 0; | |
197 | return -EINVAL; | |
198 | } | |
199 | ||
200 | struct klp_verify_args { | |
201 | const char *name; | |
202 | const unsigned long addr; | |
203 | }; | |
204 | ||
205 | static int klp_verify_callback(void *data, const char *name, | |
206 | struct module *mod, unsigned long addr) | |
207 | { | |
208 | struct klp_verify_args *args = data; | |
209 | ||
210 | if (!mod && | |
211 | !strcmp(args->name, name) && | |
212 | args->addr == addr) | |
213 | return 1; | |
214 | ||
215 | return 0; | |
216 | } | |
217 | ||
218 | static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr) | |
219 | { | |
220 | struct klp_verify_args args = { | |
221 | .name = name, | |
222 | .addr = addr, | |
223 | }; | |
9a1bd63c | 224 | int ret; |
b700e7f0 | 225 | |
9a1bd63c MB |
226 | mutex_lock(&module_mutex); |
227 | ret = kallsyms_on_each_symbol(klp_verify_callback, &args); | |
228 | mutex_unlock(&module_mutex); | |
b700e7f0 | 229 | |
9a1bd63c MB |
230 | if (!ret) { |
231 | pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n", | |
232 | name, addr); | |
233 | return -EINVAL; | |
234 | } | |
235 | ||
236 | return 0; | |
b700e7f0 SJ |
237 | } |
238 | ||
239 | static int klp_find_verify_func_addr(struct klp_object *obj, | |
240 | struct klp_func *func) | |
241 | { | |
242 | int ret; | |
243 | ||
244 | #if defined(CONFIG_RANDOMIZE_BASE) | |
5d4351ba JK |
245 | /* If KASLR has been enabled, adjust old_addr accordingly */ |
246 | if (kaslr_enabled() && func->old_addr) | |
247 | func->old_addr += kaslr_offset(); | |
b700e7f0 SJ |
248 | #endif |
249 | ||
250 | if (!func->old_addr || klp_is_module(obj)) | |
251 | ret = klp_find_object_symbol(obj->name, func->old_name, | |
252 | &func->old_addr); | |
253 | else | |
254 | ret = klp_verify_vmlinux_symbol(func->old_name, | |
255 | func->old_addr); | |
256 | ||
257 | return ret; | |
258 | } | |
259 | ||
260 | /* | |
261 | * external symbols are located outside the parent object (where the parent | |
262 | * object is either vmlinux or the kmod being patched). | |
263 | */ | |
264 | static int klp_find_external_symbol(struct module *pmod, const char *name, | |
265 | unsigned long *addr) | |
266 | { | |
267 | const struct kernel_symbol *sym; | |
268 | ||
269 | /* first, check if it's an exported symbol */ | |
270 | preempt_disable(); | |
271 | sym = find_symbol(name, NULL, NULL, true, true); | |
b700e7f0 SJ |
272 | if (sym) { |
273 | *addr = sym->value; | |
c064a0de | 274 | preempt_enable(); |
b700e7f0 SJ |
275 | return 0; |
276 | } | |
c064a0de | 277 | preempt_enable(); |
b700e7f0 SJ |
278 | |
279 | /* otherwise check if it's in another .o within the patch module */ | |
280 | return klp_find_object_symbol(pmod->name, name, addr); | |
281 | } | |
282 | ||
283 | static int klp_write_object_relocations(struct module *pmod, | |
284 | struct klp_object *obj) | |
285 | { | |
286 | int ret; | |
287 | struct klp_reloc *reloc; | |
288 | ||
289 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
290 | return -EINVAL; | |
291 | ||
292 | if (WARN_ON(!obj->relocs)) | |
293 | return -EINVAL; | |
294 | ||
295 | for (reloc = obj->relocs; reloc->name; reloc++) { | |
296 | if (!klp_is_module(obj)) { | |
297 | ret = klp_verify_vmlinux_symbol(reloc->name, | |
298 | reloc->val); | |
299 | if (ret) | |
300 | return ret; | |
301 | } else { | |
302 | /* module, reloc->val needs to be discovered */ | |
303 | if (reloc->external) | |
304 | ret = klp_find_external_symbol(pmod, | |
305 | reloc->name, | |
306 | &reloc->val); | |
307 | else | |
308 | ret = klp_find_object_symbol(obj->mod->name, | |
309 | reloc->name, | |
310 | &reloc->val); | |
311 | if (ret) | |
312 | return ret; | |
313 | } | |
314 | ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc, | |
315 | reloc->val + reloc->addend); | |
316 | if (ret) { | |
317 | pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n", | |
318 | reloc->name, reloc->val, ret); | |
319 | return ret; | |
320 | } | |
321 | } | |
322 | ||
323 | return 0; | |
324 | } | |
325 | ||
326 | static void notrace klp_ftrace_handler(unsigned long ip, | |
327 | unsigned long parent_ip, | |
3c33f5b9 | 328 | struct ftrace_ops *fops, |
b700e7f0 SJ |
329 | struct pt_regs *regs) |
330 | { | |
3c33f5b9 JP |
331 | struct klp_ops *ops; |
332 | struct klp_func *func; | |
333 | ||
334 | ops = container_of(fops, struct klp_ops, fops); | |
335 | ||
336 | rcu_read_lock(); | |
337 | func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, | |
338 | stack_node); | |
3c33f5b9 | 339 | if (WARN_ON_ONCE(!func)) |
c4ce0da8 | 340 | goto unlock; |
b700e7f0 | 341 | |
b5bfc517 | 342 | klp_arch_set_pc(regs, (unsigned long)func->new_func); |
c4ce0da8 PM |
343 | unlock: |
344 | rcu_read_unlock(); | |
b700e7f0 SJ |
345 | } |
346 | ||
0937e3b0 | 347 | static void klp_disable_func(struct klp_func *func) |
b700e7f0 | 348 | { |
3c33f5b9 | 349 | struct klp_ops *ops; |
b700e7f0 | 350 | |
0937e3b0 JP |
351 | WARN_ON(func->state != KLP_ENABLED); |
352 | WARN_ON(!func->old_addr); | |
b700e7f0 | 353 | |
3c33f5b9 JP |
354 | ops = klp_find_ops(func->old_addr); |
355 | if (WARN_ON(!ops)) | |
0937e3b0 | 356 | return; |
b700e7f0 | 357 | |
3c33f5b9 | 358 | if (list_is_singular(&ops->func_stack)) { |
0937e3b0 JP |
359 | WARN_ON(unregister_ftrace_function(&ops->fops)); |
360 | WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0)); | |
3c33f5b9 JP |
361 | |
362 | list_del_rcu(&func->stack_node); | |
363 | list_del(&ops->node); | |
364 | kfree(ops); | |
365 | } else { | |
366 | list_del_rcu(&func->stack_node); | |
367 | } | |
b700e7f0 SJ |
368 | |
369 | func->state = KLP_DISABLED; | |
b700e7f0 SJ |
370 | } |
371 | ||
372 | static int klp_enable_func(struct klp_func *func) | |
373 | { | |
3c33f5b9 | 374 | struct klp_ops *ops; |
b700e7f0 SJ |
375 | int ret; |
376 | ||
377 | if (WARN_ON(!func->old_addr)) | |
378 | return -EINVAL; | |
379 | ||
380 | if (WARN_ON(func->state != KLP_DISABLED)) | |
381 | return -EINVAL; | |
382 | ||
3c33f5b9 JP |
383 | ops = klp_find_ops(func->old_addr); |
384 | if (!ops) { | |
385 | ops = kzalloc(sizeof(*ops), GFP_KERNEL); | |
386 | if (!ops) | |
387 | return -ENOMEM; | |
388 | ||
389 | ops->fops.func = klp_ftrace_handler; | |
390 | ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS | | |
391 | FTRACE_OPS_FL_DYNAMIC | | |
392 | FTRACE_OPS_FL_IPMODIFY; | |
393 | ||
394 | list_add(&ops->node, &klp_ops); | |
395 | ||
396 | INIT_LIST_HEAD(&ops->func_stack); | |
397 | list_add_rcu(&func->stack_node, &ops->func_stack); | |
398 | ||
399 | ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 0, 0); | |
400 | if (ret) { | |
401 | pr_err("failed to set ftrace filter for function '%s' (%d)\n", | |
402 | func->old_name, ret); | |
403 | goto err; | |
404 | } | |
405 | ||
406 | ret = register_ftrace_function(&ops->fops); | |
407 | if (ret) { | |
408 | pr_err("failed to register ftrace handler for function '%s' (%d)\n", | |
409 | func->old_name, ret); | |
410 | ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0); | |
411 | goto err; | |
412 | } | |
413 | ||
b700e7f0 | 414 | |
b700e7f0 | 415 | } else { |
3c33f5b9 | 416 | list_add_rcu(&func->stack_node, &ops->func_stack); |
b700e7f0 SJ |
417 | } |
418 | ||
3c33f5b9 JP |
419 | func->state = KLP_ENABLED; |
420 | ||
dbed7dda | 421 | return 0; |
3c33f5b9 JP |
422 | |
423 | err: | |
424 | list_del_rcu(&func->stack_node); | |
425 | list_del(&ops->node); | |
426 | kfree(ops); | |
b700e7f0 SJ |
427 | return ret; |
428 | } | |
429 | ||
0937e3b0 | 430 | static void klp_disable_object(struct klp_object *obj) |
b700e7f0 SJ |
431 | { |
432 | struct klp_func *func; | |
b700e7f0 | 433 | |
8cdd043a | 434 | klp_for_each_func(obj, func) |
0937e3b0 JP |
435 | if (func->state == KLP_ENABLED) |
436 | klp_disable_func(func); | |
b700e7f0 SJ |
437 | |
438 | obj->state = KLP_DISABLED; | |
b700e7f0 SJ |
439 | } |
440 | ||
441 | static int klp_enable_object(struct klp_object *obj) | |
442 | { | |
443 | struct klp_func *func; | |
444 | int ret; | |
445 | ||
446 | if (WARN_ON(obj->state != KLP_DISABLED)) | |
447 | return -EINVAL; | |
448 | ||
449 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
450 | return -EINVAL; | |
451 | ||
8cdd043a | 452 | klp_for_each_func(obj, func) { |
b700e7f0 | 453 | ret = klp_enable_func(func); |
0937e3b0 JP |
454 | if (ret) { |
455 | klp_disable_object(obj); | |
456 | return ret; | |
457 | } | |
b700e7f0 SJ |
458 | } |
459 | obj->state = KLP_ENABLED; | |
460 | ||
461 | return 0; | |
b700e7f0 SJ |
462 | } |
463 | ||
464 | static int __klp_disable_patch(struct klp_patch *patch) | |
465 | { | |
466 | struct klp_object *obj; | |
b700e7f0 | 467 | |
83a90bb1 JP |
468 | /* enforce stacking: only the last enabled patch can be disabled */ |
469 | if (!list_is_last(&patch->list, &klp_patches) && | |
470 | list_next_entry(patch, list)->state == KLP_ENABLED) | |
471 | return -EBUSY; | |
472 | ||
b700e7f0 SJ |
473 | pr_notice("disabling patch '%s'\n", patch->mod->name); |
474 | ||
8cdd043a | 475 | klp_for_each_object(patch, obj) { |
0937e3b0 JP |
476 | if (obj->state == KLP_ENABLED) |
477 | klp_disable_object(obj); | |
b700e7f0 SJ |
478 | } |
479 | ||
480 | patch->state = KLP_DISABLED; | |
481 | ||
482 | return 0; | |
483 | } | |
484 | ||
485 | /** | |
486 | * klp_disable_patch() - disables a registered patch | |
487 | * @patch: The registered, enabled patch to be disabled | |
488 | * | |
489 | * Unregisters the patched functions from ftrace. | |
490 | * | |
491 | * Return: 0 on success, otherwise error | |
492 | */ | |
493 | int klp_disable_patch(struct klp_patch *patch) | |
494 | { | |
495 | int ret; | |
496 | ||
497 | mutex_lock(&klp_mutex); | |
498 | ||
499 | if (!klp_is_patch_registered(patch)) { | |
500 | ret = -EINVAL; | |
501 | goto err; | |
502 | } | |
503 | ||
504 | if (patch->state == KLP_DISABLED) { | |
505 | ret = -EINVAL; | |
506 | goto err; | |
507 | } | |
508 | ||
509 | ret = __klp_disable_patch(patch); | |
510 | ||
511 | err: | |
512 | mutex_unlock(&klp_mutex); | |
513 | return ret; | |
514 | } | |
515 | EXPORT_SYMBOL_GPL(klp_disable_patch); | |
516 | ||
517 | static int __klp_enable_patch(struct klp_patch *patch) | |
518 | { | |
519 | struct klp_object *obj; | |
520 | int ret; | |
521 | ||
522 | if (WARN_ON(patch->state != KLP_DISABLED)) | |
523 | return -EINVAL; | |
524 | ||
83a90bb1 JP |
525 | /* enforce stacking: only the first disabled patch can be enabled */ |
526 | if (patch->list.prev != &klp_patches && | |
527 | list_prev_entry(patch, list)->state == KLP_DISABLED) | |
528 | return -EBUSY; | |
529 | ||
b700e7f0 SJ |
530 | pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n"); |
531 | add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK); | |
532 | ||
533 | pr_notice("enabling patch '%s'\n", patch->mod->name); | |
534 | ||
8cdd043a | 535 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
536 | if (!klp_is_object_loaded(obj)) |
537 | continue; | |
538 | ||
539 | ret = klp_enable_object(obj); | |
540 | if (ret) | |
541 | goto unregister; | |
542 | } | |
543 | ||
544 | patch->state = KLP_ENABLED; | |
545 | ||
546 | return 0; | |
547 | ||
548 | unregister: | |
549 | WARN_ON(__klp_disable_patch(patch)); | |
550 | return ret; | |
551 | } | |
552 | ||
553 | /** | |
554 | * klp_enable_patch() - enables a registered patch | |
555 | * @patch: The registered, disabled patch to be enabled | |
556 | * | |
557 | * Performs the needed symbol lookups and code relocations, | |
558 | * then registers the patched functions with ftrace. | |
559 | * | |
560 | * Return: 0 on success, otherwise error | |
561 | */ | |
562 | int klp_enable_patch(struct klp_patch *patch) | |
563 | { | |
564 | int ret; | |
565 | ||
566 | mutex_lock(&klp_mutex); | |
567 | ||
568 | if (!klp_is_patch_registered(patch)) { | |
569 | ret = -EINVAL; | |
570 | goto err; | |
571 | } | |
572 | ||
573 | ret = __klp_enable_patch(patch); | |
574 | ||
575 | err: | |
576 | mutex_unlock(&klp_mutex); | |
577 | return ret; | |
578 | } | |
579 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
580 | ||
581 | /* | |
582 | * Sysfs Interface | |
583 | * | |
584 | * /sys/kernel/livepatch | |
585 | * /sys/kernel/livepatch/<patch> | |
586 | * /sys/kernel/livepatch/<patch>/enabled | |
587 | * /sys/kernel/livepatch/<patch>/<object> | |
588 | * /sys/kernel/livepatch/<patch>/<object>/<func> | |
589 | */ | |
590 | ||
591 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
592 | const char *buf, size_t count) | |
593 | { | |
594 | struct klp_patch *patch; | |
595 | int ret; | |
596 | unsigned long val; | |
597 | ||
598 | ret = kstrtoul(buf, 10, &val); | |
599 | if (ret) | |
600 | return -EINVAL; | |
601 | ||
602 | if (val != KLP_DISABLED && val != KLP_ENABLED) | |
603 | return -EINVAL; | |
604 | ||
605 | patch = container_of(kobj, struct klp_patch, kobj); | |
606 | ||
607 | mutex_lock(&klp_mutex); | |
608 | ||
609 | if (val == patch->state) { | |
610 | /* already in requested state */ | |
611 | ret = -EINVAL; | |
612 | goto err; | |
613 | } | |
614 | ||
615 | if (val == KLP_ENABLED) { | |
616 | ret = __klp_enable_patch(patch); | |
617 | if (ret) | |
618 | goto err; | |
619 | } else { | |
620 | ret = __klp_disable_patch(patch); | |
621 | if (ret) | |
622 | goto err; | |
623 | } | |
624 | ||
625 | mutex_unlock(&klp_mutex); | |
626 | ||
627 | return count; | |
628 | ||
629 | err: | |
630 | mutex_unlock(&klp_mutex); | |
631 | return ret; | |
632 | } | |
633 | ||
634 | static ssize_t enabled_show(struct kobject *kobj, | |
635 | struct kobj_attribute *attr, char *buf) | |
636 | { | |
637 | struct klp_patch *patch; | |
638 | ||
639 | patch = container_of(kobj, struct klp_patch, kobj); | |
640 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->state); | |
641 | } | |
642 | ||
643 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); | |
644 | static struct attribute *klp_patch_attrs[] = { | |
645 | &enabled_kobj_attr.attr, | |
646 | NULL | |
647 | }; | |
648 | ||
649 | static void klp_kobj_release_patch(struct kobject *kobj) | |
650 | { | |
651 | /* | |
652 | * Once we have a consistency model we'll need to module_put() the | |
653 | * patch module here. See klp_register_patch() for more details. | |
654 | */ | |
655 | } | |
656 | ||
657 | static struct kobj_type klp_ktype_patch = { | |
658 | .release = klp_kobj_release_patch, | |
659 | .sysfs_ops = &kobj_sysfs_ops, | |
660 | .default_attrs = klp_patch_attrs, | |
661 | }; | |
662 | ||
cad706df MB |
663 | static void klp_kobj_release_object(struct kobject *kobj) |
664 | { | |
665 | } | |
666 | ||
667 | static struct kobj_type klp_ktype_object = { | |
668 | .release = klp_kobj_release_object, | |
669 | .sysfs_ops = &kobj_sysfs_ops, | |
670 | }; | |
671 | ||
b700e7f0 SJ |
672 | static void klp_kobj_release_func(struct kobject *kobj) |
673 | { | |
b700e7f0 SJ |
674 | } |
675 | ||
676 | static struct kobj_type klp_ktype_func = { | |
677 | .release = klp_kobj_release_func, | |
678 | .sysfs_ops = &kobj_sysfs_ops, | |
679 | }; | |
680 | ||
681 | /* | |
682 | * Free all functions' kobjects in the array up to some limit. When limit is | |
683 | * NULL, all kobjects are freed. | |
684 | */ | |
685 | static void klp_free_funcs_limited(struct klp_object *obj, | |
686 | struct klp_func *limit) | |
687 | { | |
688 | struct klp_func *func; | |
689 | ||
690 | for (func = obj->funcs; func->old_name && func != limit; func++) | |
691 | kobject_put(&func->kobj); | |
692 | } | |
693 | ||
694 | /* Clean up when a patched object is unloaded */ | |
695 | static void klp_free_object_loaded(struct klp_object *obj) | |
696 | { | |
697 | struct klp_func *func; | |
698 | ||
699 | obj->mod = NULL; | |
700 | ||
8cdd043a | 701 | klp_for_each_func(obj, func) |
b700e7f0 SJ |
702 | func->old_addr = 0; |
703 | } | |
704 | ||
705 | /* | |
706 | * Free all objects' kobjects in the array up to some limit. When limit is | |
707 | * NULL, all kobjects are freed. | |
708 | */ | |
709 | static void klp_free_objects_limited(struct klp_patch *patch, | |
710 | struct klp_object *limit) | |
711 | { | |
712 | struct klp_object *obj; | |
713 | ||
714 | for (obj = patch->objs; obj->funcs && obj != limit; obj++) { | |
715 | klp_free_funcs_limited(obj, NULL); | |
cad706df | 716 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
717 | } |
718 | } | |
719 | ||
720 | static void klp_free_patch(struct klp_patch *patch) | |
721 | { | |
722 | klp_free_objects_limited(patch, NULL); | |
723 | if (!list_empty(&patch->list)) | |
724 | list_del(&patch->list); | |
725 | kobject_put(&patch->kobj); | |
726 | } | |
727 | ||
728 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
729 | { | |
3c33f5b9 | 730 | INIT_LIST_HEAD(&func->stack_node); |
b700e7f0 SJ |
731 | func->state = KLP_DISABLED; |
732 | ||
3c33f5b9 | 733 | return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
cad706df | 734 | &obj->kobj, "%s", func->old_name); |
b700e7f0 SJ |
735 | } |
736 | ||
737 | /* parts of the initialization that is done only when the object is loaded */ | |
738 | static int klp_init_object_loaded(struct klp_patch *patch, | |
739 | struct klp_object *obj) | |
740 | { | |
741 | struct klp_func *func; | |
742 | int ret; | |
743 | ||
744 | if (obj->relocs) { | |
745 | ret = klp_write_object_relocations(patch->mod, obj); | |
746 | if (ret) | |
747 | return ret; | |
748 | } | |
749 | ||
8cdd043a | 750 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
751 | ret = klp_find_verify_func_addr(obj, func); |
752 | if (ret) | |
753 | return ret; | |
754 | } | |
755 | ||
756 | return 0; | |
757 | } | |
758 | ||
759 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
760 | { | |
761 | struct klp_func *func; | |
762 | int ret; | |
763 | const char *name; | |
764 | ||
765 | if (!obj->funcs) | |
766 | return -EINVAL; | |
767 | ||
768 | obj->state = KLP_DISABLED; | |
8cb2c2dc | 769 | obj->mod = NULL; |
b700e7f0 SJ |
770 | |
771 | klp_find_object_module(obj); | |
772 | ||
773 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
cad706df MB |
774 | ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object, |
775 | &patch->kobj, "%s", name); | |
776 | if (ret) | |
777 | return ret; | |
b700e7f0 | 778 | |
8cdd043a | 779 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
780 | ret = klp_init_func(obj, func); |
781 | if (ret) | |
782 | goto free; | |
783 | } | |
784 | ||
785 | if (klp_is_object_loaded(obj)) { | |
786 | ret = klp_init_object_loaded(patch, obj); | |
787 | if (ret) | |
788 | goto free; | |
789 | } | |
790 | ||
791 | return 0; | |
792 | ||
793 | free: | |
794 | klp_free_funcs_limited(obj, func); | |
cad706df | 795 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
796 | return ret; |
797 | } | |
798 | ||
799 | static int klp_init_patch(struct klp_patch *patch) | |
800 | { | |
801 | struct klp_object *obj; | |
802 | int ret; | |
803 | ||
804 | if (!patch->objs) | |
805 | return -EINVAL; | |
806 | ||
807 | mutex_lock(&klp_mutex); | |
808 | ||
809 | patch->state = KLP_DISABLED; | |
810 | ||
811 | ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, | |
e0b561ee | 812 | klp_root_kobj, "%s", patch->mod->name); |
b700e7f0 SJ |
813 | if (ret) |
814 | goto unlock; | |
815 | ||
8cdd043a | 816 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
817 | ret = klp_init_object(patch, obj); |
818 | if (ret) | |
819 | goto free; | |
820 | } | |
821 | ||
99590ba5 | 822 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
823 | |
824 | mutex_unlock(&klp_mutex); | |
825 | ||
826 | return 0; | |
827 | ||
828 | free: | |
829 | klp_free_objects_limited(patch, obj); | |
830 | kobject_put(&patch->kobj); | |
831 | unlock: | |
832 | mutex_unlock(&klp_mutex); | |
833 | return ret; | |
834 | } | |
835 | ||
836 | /** | |
837 | * klp_unregister_patch() - unregisters a patch | |
838 | * @patch: Disabled patch to be unregistered | |
839 | * | |
840 | * Frees the data structures and removes the sysfs interface. | |
841 | * | |
842 | * Return: 0 on success, otherwise error | |
843 | */ | |
844 | int klp_unregister_patch(struct klp_patch *patch) | |
845 | { | |
846 | int ret = 0; | |
847 | ||
848 | mutex_lock(&klp_mutex); | |
849 | ||
850 | if (!klp_is_patch_registered(patch)) { | |
851 | ret = -EINVAL; | |
852 | goto out; | |
853 | } | |
854 | ||
855 | if (patch->state == KLP_ENABLED) { | |
856 | ret = -EBUSY; | |
857 | goto out; | |
858 | } | |
859 | ||
860 | klp_free_patch(patch); | |
861 | ||
862 | out: | |
863 | mutex_unlock(&klp_mutex); | |
864 | return ret; | |
865 | } | |
866 | EXPORT_SYMBOL_GPL(klp_unregister_patch); | |
867 | ||
868 | /** | |
869 | * klp_register_patch() - registers a patch | |
870 | * @patch: Patch to be registered | |
871 | * | |
872 | * Initializes the data structure associated with the patch and | |
873 | * creates the sysfs interface. | |
874 | * | |
875 | * Return: 0 on success, otherwise error | |
876 | */ | |
877 | int klp_register_patch(struct klp_patch *patch) | |
878 | { | |
879 | int ret; | |
880 | ||
881 | if (!klp_initialized()) | |
882 | return -ENODEV; | |
883 | ||
884 | if (!patch || !patch->mod) | |
885 | return -EINVAL; | |
886 | ||
887 | /* | |
888 | * A reference is taken on the patch module to prevent it from being | |
889 | * unloaded. Right now, we don't allow patch modules to unload since | |
890 | * there is currently no method to determine if a thread is still | |
891 | * running in the patched code contained in the patch module once | |
892 | * the ftrace registration is successful. | |
893 | */ | |
894 | if (!try_module_get(patch->mod)) | |
895 | return -ENODEV; | |
896 | ||
897 | ret = klp_init_patch(patch); | |
898 | if (ret) | |
899 | module_put(patch->mod); | |
900 | ||
901 | return ret; | |
902 | } | |
903 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
904 | ||
36e505c1 | 905 | static int klp_module_notify_coming(struct klp_patch *patch, |
b700e7f0 SJ |
906 | struct klp_object *obj) |
907 | { | |
908 | struct module *pmod = patch->mod; | |
909 | struct module *mod = obj->mod; | |
910 | int ret; | |
911 | ||
912 | ret = klp_init_object_loaded(patch, obj); | |
36e505c1 MH |
913 | if (ret) { |
914 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
915 | pmod->name, mod->name, ret); | |
916 | return ret; | |
917 | } | |
b700e7f0 SJ |
918 | |
919 | if (patch->state == KLP_DISABLED) | |
36e505c1 | 920 | return 0; |
b700e7f0 SJ |
921 | |
922 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
923 | pmod->name, mod->name); | |
924 | ||
925 | ret = klp_enable_object(obj); | |
36e505c1 MH |
926 | if (ret) |
927 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
928 | pmod->name, mod->name, ret); | |
929 | return ret; | |
b700e7f0 SJ |
930 | } |
931 | ||
932 | static void klp_module_notify_going(struct klp_patch *patch, | |
933 | struct klp_object *obj) | |
934 | { | |
935 | struct module *pmod = patch->mod; | |
936 | struct module *mod = obj->mod; | |
b700e7f0 SJ |
937 | |
938 | if (patch->state == KLP_DISABLED) | |
939 | goto disabled; | |
940 | ||
941 | pr_notice("reverting patch '%s' on unloading module '%s'\n", | |
942 | pmod->name, mod->name); | |
943 | ||
0937e3b0 | 944 | klp_disable_object(obj); |
b700e7f0 SJ |
945 | |
946 | disabled: | |
947 | klp_free_object_loaded(obj); | |
948 | } | |
949 | ||
950 | static int klp_module_notify(struct notifier_block *nb, unsigned long action, | |
951 | void *data) | |
952 | { | |
36e505c1 | 953 | int ret; |
b700e7f0 SJ |
954 | struct module *mod = data; |
955 | struct klp_patch *patch; | |
956 | struct klp_object *obj; | |
957 | ||
958 | if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING) | |
959 | return 0; | |
960 | ||
961 | mutex_lock(&klp_mutex); | |
962 | ||
8cb2c2dc PM |
963 | /* |
964 | * Each module has to know that the notifier has been called. | |
965 | * We never know what module will get patched by a new patch. | |
966 | */ | |
967 | if (action == MODULE_STATE_COMING) | |
968 | mod->klp_alive = true; | |
969 | else /* MODULE_STATE_GOING */ | |
970 | mod->klp_alive = false; | |
971 | ||
b700e7f0 | 972 | list_for_each_entry(patch, &klp_patches, list) { |
8cdd043a | 973 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
974 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) |
975 | continue; | |
976 | ||
977 | if (action == MODULE_STATE_COMING) { | |
978 | obj->mod = mod; | |
36e505c1 MH |
979 | ret = klp_module_notify_coming(patch, obj); |
980 | if (ret) { | |
981 | obj->mod = NULL; | |
982 | pr_warn("patch '%s' is in an inconsistent state!\n", | |
983 | patch->mod->name); | |
984 | } | |
b700e7f0 SJ |
985 | } else /* MODULE_STATE_GOING */ |
986 | klp_module_notify_going(patch, obj); | |
987 | ||
988 | break; | |
989 | } | |
990 | } | |
991 | ||
992 | mutex_unlock(&klp_mutex); | |
993 | ||
994 | return 0; | |
995 | } | |
996 | ||
997 | static struct notifier_block klp_module_nb = { | |
998 | .notifier_call = klp_module_notify, | |
999 | .priority = INT_MIN+1, /* called late but before ftrace notifier */ | |
1000 | }; | |
1001 | ||
26029d88 | 1002 | static int __init klp_init(void) |
b700e7f0 SJ |
1003 | { |
1004 | int ret; | |
1005 | ||
b9dfe0be JK |
1006 | ret = klp_check_compiler_support(); |
1007 | if (ret) { | |
1008 | pr_info("Your compiler is too old; turning off.\n"); | |
1009 | return -EINVAL; | |
1010 | } | |
1011 | ||
b700e7f0 SJ |
1012 | ret = register_module_notifier(&klp_module_nb); |
1013 | if (ret) | |
1014 | return ret; | |
1015 | ||
1016 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); | |
1017 | if (!klp_root_kobj) { | |
1018 | ret = -ENOMEM; | |
1019 | goto unregister; | |
1020 | } | |
1021 | ||
1022 | return 0; | |
1023 | ||
1024 | unregister: | |
1025 | unregister_module_notifier(&klp_module_nb); | |
1026 | return ret; | |
1027 | } | |
1028 | ||
1029 | module_init(klp_init); |