Commit | Line | Data |
---|---|---|
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> | |
b56b36ee | 31 | #include <asm/cacheflush.h> |
b700e7f0 | 32 | |
3c33f5b9 JP |
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 | |
b700e7f0 | 45 | */ |
3c33f5b9 JP |
46 | struct klp_ops { |
47 | struct list_head node; | |
48 | struct list_head func_stack; | |
49 | struct ftrace_ops fops; | |
50 | }; | |
b700e7f0 | 51 | |
3c33f5b9 JP |
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 | */ | |
b700e7f0 | 58 | static DEFINE_MUTEX(klp_mutex); |
3c33f5b9 | 59 | |
b700e7f0 | 60 | static LIST_HEAD(klp_patches); |
3c33f5b9 | 61 | static LIST_HEAD(klp_ops); |
b700e7f0 SJ |
62 | |
63 | static struct kobject *klp_root_kobj; | |
64 | ||
3c33f5b9 JP |
65 | static 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 | ||
b700e7f0 SJ |
80 | static bool klp_is_module(struct klp_object *obj) |
81 | { | |
82 | return obj->name; | |
83 | } | |
84 | ||
85 | static 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 */ | |
91 | static void klp_find_object_module(struct klp_object *obj) | |
92 | { | |
8cb2c2dc PM |
93 | struct module *mod; |
94 | ||
b700e7f0 SJ |
95 | if (!klp_is_module(obj)) |
96 | return; | |
97 | ||
98 | mutex_lock(&module_mutex); | |
99 | /* | |
8cb2c2dc PM |
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 | * a going module handler instead. | |
103 | */ | |
104 | mod = find_module(obj->name); | |
105 | /* | |
106 | * Do not mess work of the module coming and going notifiers. | |
107 | * Note that the patch might still be needed before the going handler | |
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. | |
b700e7f0 | 111 | */ |
8cb2c2dc PM |
112 | if (mod && mod->klp_alive) |
113 | obj->mod = mod; | |
114 | ||
b700e7f0 SJ |
115 | mutex_unlock(&module_mutex); |
116 | } | |
117 | ||
118 | /* klp_mutex must be held by caller */ | |
119 | static 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 | ||
130 | static bool klp_initialized(void) | |
131 | { | |
e76ff06a | 132 | return !!klp_root_kobj; |
b700e7f0 SJ |
133 | } |
134 | ||
135 | struct klp_find_arg { | |
136 | const char *objname; | |
137 | const char *name; | |
138 | unsigned long addr; | |
b700e7f0 | 139 | unsigned long count; |
b2b018ef | 140 | unsigned long pos; |
b700e7f0 SJ |
141 | }; |
142 | ||
143 | static 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 | ||
b700e7f0 SJ |
157 | args->addr = addr; |
158 | args->count++; | |
159 | ||
b2b018ef CA |
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 | ||
b700e7f0 SJ |
168 | return 0; |
169 | } | |
170 | ||
171 | static int klp_find_object_symbol(const char *objname, const char *name, | |
b2b018ef | 172 | unsigned long sympos, unsigned long *addr) |
b700e7f0 SJ |
173 | { |
174 | struct klp_find_arg args = { | |
175 | .objname = objname, | |
176 | .name = name, | |
177 | .addr = 0, | |
b2b018ef CA |
178 | .count = 0, |
179 | .pos = sympos, | |
b700e7f0 SJ |
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 | 185 | |
b2b018ef CA |
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) | |
b700e7f0 | 191 | pr_err("symbol '%s' not found in symbol table\n", name); |
b2b018ef | 192 | else if (args.count > 1 && sympos == 0) { |
b700e7f0 SJ |
193 | pr_err("unresolvable ambiguity (%lu matches) on symbol '%s' in object '%s'\n", |
194 | args.count, name, objname); | |
b2b018ef CA |
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 { | |
b700e7f0 SJ |
199 | *addr = args.addr; |
200 | return 0; | |
201 | } | |
202 | ||
203 | *addr = 0; | |
204 | return -EINVAL; | |
205 | } | |
206 | ||
b700e7f0 SJ |
207 | /* |
208 | * external symbols are located outside the parent object (where the parent | |
209 | * object is either vmlinux or the kmod being patched). | |
210 | */ | |
211 | static 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); | |
b700e7f0 SJ |
219 | if (sym) { |
220 | *addr = sym->value; | |
c064a0de | 221 | preempt_enable(); |
b700e7f0 SJ |
222 | return 0; |
223 | } | |
c064a0de | 224 | preempt_enable(); |
b700e7f0 | 225 | |
b2b018ef CA |
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); | |
b700e7f0 SJ |
231 | } |
232 | ||
233 | static int klp_write_object_relocations(struct module *pmod, | |
234 | struct klp_object *obj) | |
235 | { | |
b56b36ee | 236 | int ret = 0; |
064c89df | 237 | unsigned long val; |
b700e7f0 SJ |
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 | ||
b56b36ee JP |
246 | module_disable_ro(pmod); |
247 | ||
b700e7f0 | 248 | for (reloc = obj->relocs; reloc->name; reloc++) { |
064c89df CA |
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); | |
b56b36ee JP |
254 | ret = -EINVAL; |
255 | goto out; | |
064c89df CA |
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) | |
b56b36ee | 264 | goto out; |
064c89df | 265 | |
b700e7f0 | 266 | ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc, |
064c89df | 267 | val + reloc->addend); |
b700e7f0 SJ |
268 | if (ret) { |
269 | pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n", | |
064c89df | 270 | reloc->name, val, ret); |
b56b36ee | 271 | goto out; |
b700e7f0 SJ |
272 | } |
273 | } | |
274 | ||
b56b36ee JP |
275 | out: |
276 | module_enable_ro(pmod); | |
277 | return ret; | |
b700e7f0 SJ |
278 | } |
279 | ||
280 | static void notrace klp_ftrace_handler(unsigned long ip, | |
281 | unsigned long parent_ip, | |
3c33f5b9 | 282 | struct ftrace_ops *fops, |
b700e7f0 SJ |
283 | struct pt_regs *regs) |
284 | { | |
3c33f5b9 JP |
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); | |
3c33f5b9 | 293 | if (WARN_ON_ONCE(!func)) |
c4ce0da8 | 294 | goto unlock; |
b700e7f0 | 295 | |
b5bfc517 | 296 | klp_arch_set_pc(regs, (unsigned long)func->new_func); |
c4ce0da8 PM |
297 | unlock: |
298 | rcu_read_unlock(); | |
b700e7f0 SJ |
299 | } |
300 | ||
0937e3b0 | 301 | static void klp_disable_func(struct klp_func *func) |
b700e7f0 | 302 | { |
3c33f5b9 | 303 | struct klp_ops *ops; |
b700e7f0 | 304 | |
225f58fb MH |
305 | if (WARN_ON(func->state != KLP_ENABLED)) |
306 | return; | |
307 | if (WARN_ON(!func->old_addr)) | |
308 | return; | |
b700e7f0 | 309 | |
3c33f5b9 JP |
310 | ops = klp_find_ops(func->old_addr); |
311 | if (WARN_ON(!ops)) | |
0937e3b0 | 312 | return; |
b700e7f0 | 313 | |
3c33f5b9 | 314 | if (list_is_singular(&ops->func_stack)) { |
0937e3b0 JP |
315 | WARN_ON(unregister_ftrace_function(&ops->fops)); |
316 | WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0)); | |
3c33f5b9 JP |
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 | } | |
b700e7f0 SJ |
324 | |
325 | func->state = KLP_DISABLED; | |
b700e7f0 SJ |
326 | } |
327 | ||
328 | static int klp_enable_func(struct klp_func *func) | |
329 | { | |
3c33f5b9 | 330 | struct klp_ops *ops; |
b700e7f0 SJ |
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 | ||
3c33f5b9 JP |
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 | ||
b700e7f0 | 370 | |
b700e7f0 | 371 | } else { |
3c33f5b9 | 372 | list_add_rcu(&func->stack_node, &ops->func_stack); |
b700e7f0 SJ |
373 | } |
374 | ||
3c33f5b9 JP |
375 | func->state = KLP_ENABLED; |
376 | ||
dbed7dda | 377 | return 0; |
3c33f5b9 JP |
378 | |
379 | err: | |
380 | list_del_rcu(&func->stack_node); | |
381 | list_del(&ops->node); | |
382 | kfree(ops); | |
b700e7f0 SJ |
383 | return ret; |
384 | } | |
385 | ||
0937e3b0 | 386 | static void klp_disable_object(struct klp_object *obj) |
b700e7f0 SJ |
387 | { |
388 | struct klp_func *func; | |
b700e7f0 | 389 | |
8cdd043a | 390 | klp_for_each_func(obj, func) |
0937e3b0 JP |
391 | if (func->state == KLP_ENABLED) |
392 | klp_disable_func(func); | |
b700e7f0 SJ |
393 | |
394 | obj->state = KLP_DISABLED; | |
b700e7f0 SJ |
395 | } |
396 | ||
397 | static 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 | ||
8cdd043a | 408 | klp_for_each_func(obj, func) { |
b700e7f0 | 409 | ret = klp_enable_func(func); |
0937e3b0 JP |
410 | if (ret) { |
411 | klp_disable_object(obj); | |
412 | return ret; | |
413 | } | |
b700e7f0 SJ |
414 | } |
415 | obj->state = KLP_ENABLED; | |
416 | ||
417 | return 0; | |
b700e7f0 SJ |
418 | } |
419 | ||
420 | static int __klp_disable_patch(struct klp_patch *patch) | |
421 | { | |
422 | struct klp_object *obj; | |
b700e7f0 | 423 | |
83a90bb1 JP |
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 | ||
b700e7f0 SJ |
429 | pr_notice("disabling patch '%s'\n", patch->mod->name); |
430 | ||
8cdd043a | 431 | klp_for_each_object(patch, obj) { |
0937e3b0 JP |
432 | if (obj->state == KLP_ENABLED) |
433 | klp_disable_object(obj); | |
b700e7f0 SJ |
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 | */ | |
449 | int 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 | ||
467 | err: | |
468 | mutex_unlock(&klp_mutex); | |
469 | return ret; | |
470 | } | |
471 | EXPORT_SYMBOL_GPL(klp_disable_patch); | |
472 | ||
473 | static 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 | ||
83a90bb1 JP |
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 | ||
b700e7f0 SJ |
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 | ||
8cdd043a | 491 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
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 | ||
504 | unregister: | |
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 | */ | |
518 | int 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 | ||
531 | err: | |
532 | mutex_unlock(&klp_mutex); | |
533 | return ret; | |
534 | } | |
535 | EXPORT_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> | |
444f9e99 | 544 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 SJ |
545 | */ |
546 | ||
547 | static 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 | ||
585 | err: | |
586 | mutex_unlock(&klp_mutex); | |
587 | return ret; | |
588 | } | |
589 | ||
590 | static 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 | ||
599 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); | |
600 | static struct attribute *klp_patch_attrs[] = { | |
601 | &enabled_kobj_attr.attr, | |
602 | NULL | |
603 | }; | |
604 | ||
605 | static 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 | ||
613 | static 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 | ||
cad706df MB |
619 | static void klp_kobj_release_object(struct kobject *kobj) |
620 | { | |
621 | } | |
622 | ||
623 | static struct kobj_type klp_ktype_object = { | |
624 | .release = klp_kobj_release_object, | |
625 | .sysfs_ops = &kobj_sysfs_ops, | |
626 | }; | |
627 | ||
b700e7f0 SJ |
628 | static void klp_kobj_release_func(struct kobject *kobj) |
629 | { | |
b700e7f0 SJ |
630 | } |
631 | ||
632 | static 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 | */ | |
641 | static 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 */ | |
651 | static void klp_free_object_loaded(struct klp_object *obj) | |
652 | { | |
653 | struct klp_func *func; | |
654 | ||
655 | obj->mod = NULL; | |
656 | ||
8cdd043a | 657 | klp_for_each_func(obj, func) |
b700e7f0 SJ |
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 | */ | |
665 | static 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); | |
cad706df | 672 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
673 | } |
674 | } | |
675 | ||
676 | static 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 | ||
684 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
685 | { | |
3c33f5b9 | 686 | INIT_LIST_HEAD(&func->stack_node); |
b700e7f0 SJ |
687 | func->state = KLP_DISABLED; |
688 | ||
444f9e99 CA |
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 | */ | |
3c33f5b9 | 694 | return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
444f9e99 CA |
695 | &obj->kobj, "%s,%lu", func->old_name, |
696 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
697 | } |
698 | ||
699 | /* parts of the initialization that is done only when the object is loaded */ | |
700 | static 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 | ||
8cdd043a | 712 | klp_for_each_func(obj, func) { |
b2b018ef CA |
713 | ret = klp_find_object_symbol(obj->name, func->old_name, |
714 | func->old_sympos, | |
715 | &func->old_addr); | |
b700e7f0 SJ |
716 | if (ret) |
717 | return ret; | |
718 | } | |
719 | ||
720 | return 0; | |
721 | } | |
722 | ||
723 | static 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; | |
8cb2c2dc | 733 | obj->mod = NULL; |
b700e7f0 SJ |
734 | |
735 | klp_find_object_module(obj); | |
736 | ||
737 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
cad706df MB |
738 | ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object, |
739 | &patch->kobj, "%s", name); | |
740 | if (ret) | |
741 | return ret; | |
b700e7f0 | 742 | |
8cdd043a | 743 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
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 | ||
757 | free: | |
758 | klp_free_funcs_limited(obj, func); | |
cad706df | 759 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
760 | return ret; |
761 | } | |
762 | ||
763 | static 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, | |
e0b561ee | 776 | klp_root_kobj, "%s", patch->mod->name); |
b700e7f0 SJ |
777 | if (ret) |
778 | goto unlock; | |
779 | ||
8cdd043a | 780 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
781 | ret = klp_init_object(patch, obj); |
782 | if (ret) | |
783 | goto free; | |
784 | } | |
785 | ||
99590ba5 | 786 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
787 | |
788 | mutex_unlock(&klp_mutex); | |
789 | ||
790 | return 0; | |
791 | ||
792 | free: | |
793 | klp_free_objects_limited(patch, obj); | |
794 | kobject_put(&patch->kobj); | |
795 | unlock: | |
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 | */ | |
808 | int 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 | ||
826 | out: | |
827 | mutex_unlock(&klp_mutex); | |
828 | return ret; | |
829 | } | |
830 | EXPORT_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 | */ | |
841 | int 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 | } | |
867 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
868 | ||
36e505c1 | 869 | static int klp_module_notify_coming(struct klp_patch *patch, |
b700e7f0 SJ |
870 | struct klp_object *obj) |
871 | { | |
872 | struct module *pmod = patch->mod; | |
873 | struct module *mod = obj->mod; | |
874 | int ret; | |
875 | ||
876 | ret = klp_init_object_loaded(patch, obj); | |
36e505c1 MH |
877 | if (ret) { |
878 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
879 | pmod->name, mod->name, ret); | |
880 | return ret; | |
881 | } | |
b700e7f0 SJ |
882 | |
883 | if (patch->state == KLP_DISABLED) | |
36e505c1 | 884 | return 0; |
b700e7f0 SJ |
885 | |
886 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
887 | pmod->name, mod->name); | |
888 | ||
889 | ret = klp_enable_object(obj); | |
36e505c1 MH |
890 | if (ret) |
891 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
892 | pmod->name, mod->name, ret); | |
893 | return ret; | |
b700e7f0 SJ |
894 | } |
895 | ||
896 | static void klp_module_notify_going(struct klp_patch *patch, | |
897 | struct klp_object *obj) | |
898 | { | |
899 | struct module *pmod = patch->mod; | |
900 | struct module *mod = obj->mod; | |
b700e7f0 SJ |
901 | |
902 | if (patch->state == KLP_DISABLED) | |
903 | goto disabled; | |
904 | ||
905 | pr_notice("reverting patch '%s' on unloading module '%s'\n", | |
906 | pmod->name, mod->name); | |
907 | ||
0937e3b0 | 908 | klp_disable_object(obj); |
b700e7f0 SJ |
909 | |
910 | disabled: | |
911 | klp_free_object_loaded(obj); | |
912 | } | |
913 | ||
914 | static int klp_module_notify(struct notifier_block *nb, unsigned long action, | |
915 | void *data) | |
916 | { | |
36e505c1 | 917 | int ret; |
b700e7f0 SJ |
918 | struct module *mod = data; |
919 | struct klp_patch *patch; | |
920 | struct klp_object *obj; | |
921 | ||
922 | if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING) | |
923 | return 0; | |
924 | ||
925 | mutex_lock(&klp_mutex); | |
926 | ||
8cb2c2dc PM |
927 | /* |
928 | * Each module has to know that the notifier has been called. | |
929 | * We never know what module will get patched by a new patch. | |
930 | */ | |
931 | if (action == MODULE_STATE_COMING) | |
932 | mod->klp_alive = true; | |
933 | else /* MODULE_STATE_GOING */ | |
934 | mod->klp_alive = false; | |
935 | ||
b700e7f0 | 936 | list_for_each_entry(patch, &klp_patches, list) { |
8cdd043a | 937 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
938 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) |
939 | continue; | |
940 | ||
941 | if (action == MODULE_STATE_COMING) { | |
942 | obj->mod = mod; | |
36e505c1 MH |
943 | ret = klp_module_notify_coming(patch, obj); |
944 | if (ret) { | |
945 | obj->mod = NULL; | |
946 | pr_warn("patch '%s' is in an inconsistent state!\n", | |
947 | patch->mod->name); | |
948 | } | |
b700e7f0 SJ |
949 | } else /* MODULE_STATE_GOING */ |
950 | klp_module_notify_going(patch, obj); | |
951 | ||
952 | break; | |
953 | } | |
954 | } | |
955 | ||
956 | mutex_unlock(&klp_mutex); | |
957 | ||
958 | return 0; | |
959 | } | |
960 | ||
961 | static struct notifier_block klp_module_nb = { | |
962 | .notifier_call = klp_module_notify, | |
963 | .priority = INT_MIN+1, /* called late but before ftrace notifier */ | |
964 | }; | |
965 | ||
26029d88 | 966 | static int __init klp_init(void) |
b700e7f0 SJ |
967 | { |
968 | int ret; | |
969 | ||
b9dfe0be JK |
970 | ret = klp_check_compiler_support(); |
971 | if (ret) { | |
972 | pr_info("Your compiler is too old; turning off.\n"); | |
973 | return -EINVAL; | |
974 | } | |
975 | ||
b700e7f0 SJ |
976 | ret = register_module_notifier(&klp_module_nb); |
977 | if (ret) | |
978 | return ret; | |
979 | ||
980 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); | |
981 | if (!klp_root_kobj) { | |
982 | ret = -ENOMEM; | |
983 | goto unregister; | |
984 | } | |
985 | ||
986 | return 0; | |
987 | ||
988 | unregister: | |
989 | unregister_module_notifier(&klp_module_nb); | |
990 | return ret; | |
991 | } | |
992 | ||
993 | module_init(klp_init); |