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Commit | Line | Data |
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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> | |
425595a7 JY |
31 | #include <linux/elf.h> |
32 | #include <linux/moduleloader.h> | |
b56b36ee | 33 | #include <asm/cacheflush.h> |
b700e7f0 | 34 | |
3c33f5b9 JP |
35 | /** |
36 | * struct klp_ops - structure for tracking registered ftrace ops structs | |
37 | * | |
38 | * A single ftrace_ops is shared between all enabled replacement functions | |
39 | * (klp_func structs) which have the same old_addr. This allows the switch | |
40 | * between function versions to happen instantaneously by updating the klp_ops | |
41 | * struct's func_stack list. The winner is the klp_func at the top of the | |
42 | * func_stack (front of the list). | |
43 | * | |
44 | * @node: node for the global klp_ops list | |
45 | * @func_stack: list head for the stack of klp_func's (active func is on top) | |
46 | * @fops: registered ftrace ops struct | |
b700e7f0 | 47 | */ |
3c33f5b9 JP |
48 | struct klp_ops { |
49 | struct list_head node; | |
50 | struct list_head func_stack; | |
51 | struct ftrace_ops fops; | |
52 | }; | |
b700e7f0 | 53 | |
3c33f5b9 JP |
54 | /* |
55 | * The klp_mutex protects the global lists and state transitions of any | |
56 | * structure reachable from them. References to any structure must be obtained | |
57 | * under mutex protection (except in klp_ftrace_handler(), which uses RCU to | |
58 | * ensure it gets consistent data). | |
59 | */ | |
b700e7f0 | 60 | static DEFINE_MUTEX(klp_mutex); |
3c33f5b9 | 61 | |
b700e7f0 | 62 | static LIST_HEAD(klp_patches); |
3c33f5b9 | 63 | static LIST_HEAD(klp_ops); |
b700e7f0 SJ |
64 | |
65 | static struct kobject *klp_root_kobj; | |
66 | ||
3c33f5b9 JP |
67 | static struct klp_ops *klp_find_ops(unsigned long old_addr) |
68 | { | |
69 | struct klp_ops *ops; | |
70 | struct klp_func *func; | |
71 | ||
72 | list_for_each_entry(ops, &klp_ops, node) { | |
73 | func = list_first_entry(&ops->func_stack, struct klp_func, | |
74 | stack_node); | |
75 | if (func->old_addr == old_addr) | |
76 | return ops; | |
77 | } | |
78 | ||
79 | return NULL; | |
80 | } | |
81 | ||
b700e7f0 SJ |
82 | static bool klp_is_module(struct klp_object *obj) |
83 | { | |
84 | return obj->name; | |
85 | } | |
86 | ||
87 | static bool klp_is_object_loaded(struct klp_object *obj) | |
88 | { | |
89 | return !obj->name || obj->mod; | |
90 | } | |
91 | ||
92 | /* sets obj->mod if object is not vmlinux and module is found */ | |
93 | static void klp_find_object_module(struct klp_object *obj) | |
94 | { | |
8cb2c2dc PM |
95 | struct module *mod; |
96 | ||
b700e7f0 SJ |
97 | if (!klp_is_module(obj)) |
98 | return; | |
99 | ||
100 | mutex_lock(&module_mutex); | |
101 | /* | |
8cb2c2dc PM |
102 | * We do not want to block removal of patched modules and therefore |
103 | * we do not take a reference here. The patches are removed by | |
7e545d6e | 104 | * klp_module_going() instead. |
8cb2c2dc PM |
105 | */ |
106 | mod = find_module(obj->name); | |
107 | /* | |
7e545d6e JY |
108 | * Do not mess work of klp_module_coming() and klp_module_going(). |
109 | * Note that the patch might still be needed before klp_module_going() | |
8cb2c2dc PM |
110 | * is called. Module functions can be called even in the GOING state |
111 | * until mod->exit() finishes. This is especially important for | |
112 | * patches that modify semantic of the functions. | |
b700e7f0 | 113 | */ |
8cb2c2dc PM |
114 | if (mod && mod->klp_alive) |
115 | obj->mod = mod; | |
116 | ||
b700e7f0 SJ |
117 | mutex_unlock(&module_mutex); |
118 | } | |
119 | ||
120 | /* klp_mutex must be held by caller */ | |
121 | static bool klp_is_patch_registered(struct klp_patch *patch) | |
122 | { | |
123 | struct klp_patch *mypatch; | |
124 | ||
125 | list_for_each_entry(mypatch, &klp_patches, list) | |
126 | if (mypatch == patch) | |
127 | return true; | |
128 | ||
129 | return false; | |
130 | } | |
131 | ||
132 | static bool klp_initialized(void) | |
133 | { | |
e76ff06a | 134 | return !!klp_root_kobj; |
b700e7f0 SJ |
135 | } |
136 | ||
137 | struct klp_find_arg { | |
138 | const char *objname; | |
139 | const char *name; | |
140 | unsigned long addr; | |
b700e7f0 | 141 | unsigned long count; |
b2b018ef | 142 | unsigned long pos; |
b700e7f0 SJ |
143 | }; |
144 | ||
145 | static int klp_find_callback(void *data, const char *name, | |
146 | struct module *mod, unsigned long addr) | |
147 | { | |
148 | struct klp_find_arg *args = data; | |
149 | ||
150 | if ((mod && !args->objname) || (!mod && args->objname)) | |
151 | return 0; | |
152 | ||
153 | if (strcmp(args->name, name)) | |
154 | return 0; | |
155 | ||
156 | if (args->objname && strcmp(args->objname, mod->name)) | |
157 | return 0; | |
158 | ||
b700e7f0 SJ |
159 | args->addr = addr; |
160 | args->count++; | |
161 | ||
b2b018ef CA |
162 | /* |
163 | * Finish the search when the symbol is found for the desired position | |
164 | * or the position is not defined for a non-unique symbol. | |
165 | */ | |
166 | if ((args->pos && (args->count == args->pos)) || | |
167 | (!args->pos && (args->count > 1))) | |
168 | return 1; | |
169 | ||
b700e7f0 SJ |
170 | return 0; |
171 | } | |
172 | ||
173 | static int klp_find_object_symbol(const char *objname, const char *name, | |
b2b018ef | 174 | unsigned long sympos, unsigned long *addr) |
b700e7f0 SJ |
175 | { |
176 | struct klp_find_arg args = { | |
177 | .objname = objname, | |
178 | .name = name, | |
179 | .addr = 0, | |
b2b018ef CA |
180 | .count = 0, |
181 | .pos = sympos, | |
b700e7f0 SJ |
182 | }; |
183 | ||
9a1bd63c | 184 | mutex_lock(&module_mutex); |
b700e7f0 | 185 | kallsyms_on_each_symbol(klp_find_callback, &args); |
9a1bd63c | 186 | mutex_unlock(&module_mutex); |
b700e7f0 | 187 | |
b2b018ef CA |
188 | /* |
189 | * Ensure an address was found. If sympos is 0, ensure symbol is unique; | |
190 | * otherwise ensure the symbol position count matches sympos. | |
191 | */ | |
192 | if (args.addr == 0) | |
b700e7f0 | 193 | pr_err("symbol '%s' not found in symbol table\n", name); |
b2b018ef | 194 | else if (args.count > 1 && sympos == 0) { |
f995b5f7 PM |
195 | pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n", |
196 | name, objname); | |
b2b018ef CA |
197 | } else if (sympos != args.count && sympos > 0) { |
198 | pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n", | |
199 | sympos, name, objname ? objname : "vmlinux"); | |
200 | } else { | |
b700e7f0 SJ |
201 | *addr = args.addr; |
202 | return 0; | |
203 | } | |
204 | ||
205 | *addr = 0; | |
206 | return -EINVAL; | |
207 | } | |
208 | ||
425595a7 | 209 | static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod) |
b700e7f0 | 210 | { |
425595a7 JY |
211 | int i, cnt, vmlinux, ret; |
212 | char objname[MODULE_NAME_LEN]; | |
213 | char symname[KSYM_NAME_LEN]; | |
214 | char *strtab = pmod->core_kallsyms.strtab; | |
215 | Elf_Rela *relas; | |
216 | Elf_Sym *sym; | |
217 | unsigned long sympos, addr; | |
b700e7f0 | 218 | |
b2b018ef | 219 | /* |
425595a7 JY |
220 | * Since the field widths for objname and symname in the sscanf() |
221 | * call are hard-coded and correspond to MODULE_NAME_LEN and | |
222 | * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN | |
223 | * and KSYM_NAME_LEN have the values we expect them to have. | |
224 | * | |
225 | * Because the value of MODULE_NAME_LEN can differ among architectures, | |
226 | * we use the smallest/strictest upper bound possible (56, based on | |
227 | * the current definition of MODULE_NAME_LEN) to prevent overflows. | |
b2b018ef | 228 | */ |
425595a7 JY |
229 | BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); |
230 | ||
231 | relas = (Elf_Rela *) relasec->sh_addr; | |
232 | /* For each rela in this klp relocation section */ | |
233 | for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { | |
234 | sym = pmod->core_kallsyms.symtab + ELF_R_SYM(relas[i].r_info); | |
235 | if (sym->st_shndx != SHN_LIVEPATCH) { | |
236 | pr_err("symbol %s is not marked as a livepatch symbol", | |
237 | strtab + sym->st_name); | |
238 | return -EINVAL; | |
239 | } | |
240 | ||
241 | /* Format: .klp.sym.objname.symname,sympos */ | |
242 | cnt = sscanf(strtab + sym->st_name, | |
243 | ".klp.sym.%55[^.].%127[^,],%lu", | |
244 | objname, symname, &sympos); | |
245 | if (cnt != 3) { | |
246 | pr_err("symbol %s has an incorrectly formatted name", | |
247 | strtab + sym->st_name); | |
248 | return -EINVAL; | |
249 | } | |
250 | ||
251 | /* klp_find_object_symbol() treats a NULL objname as vmlinux */ | |
252 | vmlinux = !strcmp(objname, "vmlinux"); | |
253 | ret = klp_find_object_symbol(vmlinux ? NULL : objname, | |
254 | symname, sympos, &addr); | |
255 | if (ret) | |
256 | return ret; | |
257 | ||
258 | sym->st_value = addr; | |
259 | } | |
260 | ||
261 | return 0; | |
b700e7f0 SJ |
262 | } |
263 | ||
264 | static int klp_write_object_relocations(struct module *pmod, | |
265 | struct klp_object *obj) | |
266 | { | |
425595a7 JY |
267 | int i, cnt, ret = 0; |
268 | const char *objname, *secname; | |
269 | char sec_objname[MODULE_NAME_LEN]; | |
270 | Elf_Shdr *sec; | |
b700e7f0 SJ |
271 | |
272 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
273 | return -EINVAL; | |
274 | ||
425595a7 | 275 | objname = klp_is_module(obj) ? obj->name : "vmlinux"; |
b700e7f0 | 276 | |
425595a7 JY |
277 | /* For each klp relocation section */ |
278 | for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) { | |
279 | sec = pmod->klp_info->sechdrs + i; | |
280 | secname = pmod->klp_info->secstrings + sec->sh_name; | |
281 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
282 | continue; | |
b56b36ee | 283 | |
425595a7 JY |
284 | /* |
285 | * Format: .klp.rela.sec_objname.section_name | |
286 | * See comment in klp_resolve_symbols() for an explanation | |
287 | * of the selected field width value. | |
288 | */ | |
289 | cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname); | |
290 | if (cnt != 1) { | |
291 | pr_err("section %s has an incorrectly formatted name", | |
292 | secname); | |
293 | ret = -EINVAL; | |
294 | break; | |
295 | } | |
b56b36ee | 296 | |
425595a7 JY |
297 | if (strcmp(objname, sec_objname)) |
298 | continue; | |
b56b36ee | 299 | |
425595a7 | 300 | ret = klp_resolve_symbols(sec, pmod); |
064c89df | 301 | if (ret) |
425595a7 | 302 | break; |
064c89df | 303 | |
425595a7 JY |
304 | ret = apply_relocate_add(pmod->klp_info->sechdrs, |
305 | pmod->core_kallsyms.strtab, | |
306 | pmod->klp_info->symndx, i, pmod); | |
307 | if (ret) | |
308 | break; | |
b700e7f0 SJ |
309 | } |
310 | ||
b56b36ee | 311 | return ret; |
b700e7f0 SJ |
312 | } |
313 | ||
314 | static void notrace klp_ftrace_handler(unsigned long ip, | |
315 | unsigned long parent_ip, | |
3c33f5b9 | 316 | struct ftrace_ops *fops, |
b700e7f0 SJ |
317 | struct pt_regs *regs) |
318 | { | |
3c33f5b9 JP |
319 | struct klp_ops *ops; |
320 | struct klp_func *func; | |
321 | ||
322 | ops = container_of(fops, struct klp_ops, fops); | |
323 | ||
324 | rcu_read_lock(); | |
325 | func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, | |
326 | stack_node); | |
3c33f5b9 | 327 | if (WARN_ON_ONCE(!func)) |
c4ce0da8 | 328 | goto unlock; |
b700e7f0 | 329 | |
b5bfc517 | 330 | klp_arch_set_pc(regs, (unsigned long)func->new_func); |
c4ce0da8 PM |
331 | unlock: |
332 | rcu_read_unlock(); | |
b700e7f0 SJ |
333 | } |
334 | ||
28e7cbd3 ME |
335 | /* |
336 | * Convert a function address into the appropriate ftrace location. | |
337 | * | |
338 | * Usually this is just the address of the function, but on some architectures | |
339 | * it's more complicated so allow them to provide a custom behaviour. | |
340 | */ | |
341 | #ifndef klp_get_ftrace_location | |
342 | static unsigned long klp_get_ftrace_location(unsigned long faddr) | |
343 | { | |
344 | return faddr; | |
345 | } | |
346 | #endif | |
347 | ||
0937e3b0 | 348 | static void klp_disable_func(struct klp_func *func) |
b700e7f0 | 349 | { |
3c33f5b9 | 350 | struct klp_ops *ops; |
b700e7f0 | 351 | |
225f58fb MH |
352 | if (WARN_ON(func->state != KLP_ENABLED)) |
353 | return; | |
354 | if (WARN_ON(!func->old_addr)) | |
355 | return; | |
b700e7f0 | 356 | |
3c33f5b9 JP |
357 | ops = klp_find_ops(func->old_addr); |
358 | if (WARN_ON(!ops)) | |
0937e3b0 | 359 | return; |
b700e7f0 | 360 | |
3c33f5b9 | 361 | if (list_is_singular(&ops->func_stack)) { |
28e7cbd3 ME |
362 | unsigned long ftrace_loc; |
363 | ||
364 | ftrace_loc = klp_get_ftrace_location(func->old_addr); | |
365 | if (WARN_ON(!ftrace_loc)) | |
366 | return; | |
367 | ||
0937e3b0 | 368 | WARN_ON(unregister_ftrace_function(&ops->fops)); |
28e7cbd3 | 369 | WARN_ON(ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0)); |
3c33f5b9 JP |
370 | |
371 | list_del_rcu(&func->stack_node); | |
372 | list_del(&ops->node); | |
373 | kfree(ops); | |
374 | } else { | |
375 | list_del_rcu(&func->stack_node); | |
376 | } | |
b700e7f0 SJ |
377 | |
378 | func->state = KLP_DISABLED; | |
b700e7f0 SJ |
379 | } |
380 | ||
381 | static int klp_enable_func(struct klp_func *func) | |
382 | { | |
3c33f5b9 | 383 | struct klp_ops *ops; |
b700e7f0 SJ |
384 | int ret; |
385 | ||
386 | if (WARN_ON(!func->old_addr)) | |
387 | return -EINVAL; | |
388 | ||
389 | if (WARN_ON(func->state != KLP_DISABLED)) | |
390 | return -EINVAL; | |
391 | ||
3c33f5b9 JP |
392 | ops = klp_find_ops(func->old_addr); |
393 | if (!ops) { | |
28e7cbd3 ME |
394 | unsigned long ftrace_loc; |
395 | ||
396 | ftrace_loc = klp_get_ftrace_location(func->old_addr); | |
397 | if (!ftrace_loc) { | |
398 | pr_err("failed to find location for function '%s'\n", | |
399 | func->old_name); | |
400 | return -EINVAL; | |
401 | } | |
402 | ||
3c33f5b9 JP |
403 | ops = kzalloc(sizeof(*ops), GFP_KERNEL); |
404 | if (!ops) | |
405 | return -ENOMEM; | |
406 | ||
407 | ops->fops.func = klp_ftrace_handler; | |
408 | ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS | | |
409 | FTRACE_OPS_FL_DYNAMIC | | |
410 | FTRACE_OPS_FL_IPMODIFY; | |
411 | ||
412 | list_add(&ops->node, &klp_ops); | |
413 | ||
414 | INIT_LIST_HEAD(&ops->func_stack); | |
415 | list_add_rcu(&func->stack_node, &ops->func_stack); | |
416 | ||
28e7cbd3 | 417 | ret = ftrace_set_filter_ip(&ops->fops, ftrace_loc, 0, 0); |
3c33f5b9 JP |
418 | if (ret) { |
419 | pr_err("failed to set ftrace filter for function '%s' (%d)\n", | |
420 | func->old_name, ret); | |
421 | goto err; | |
422 | } | |
423 | ||
424 | ret = register_ftrace_function(&ops->fops); | |
425 | if (ret) { | |
426 | pr_err("failed to register ftrace handler for function '%s' (%d)\n", | |
427 | func->old_name, ret); | |
28e7cbd3 | 428 | ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0); |
3c33f5b9 JP |
429 | goto err; |
430 | } | |
431 | ||
b700e7f0 | 432 | |
b700e7f0 | 433 | } else { |
3c33f5b9 | 434 | list_add_rcu(&func->stack_node, &ops->func_stack); |
b700e7f0 SJ |
435 | } |
436 | ||
3c33f5b9 JP |
437 | func->state = KLP_ENABLED; |
438 | ||
dbed7dda | 439 | return 0; |
3c33f5b9 JP |
440 | |
441 | err: | |
442 | list_del_rcu(&func->stack_node); | |
443 | list_del(&ops->node); | |
444 | kfree(ops); | |
b700e7f0 SJ |
445 | return ret; |
446 | } | |
447 | ||
0937e3b0 | 448 | static void klp_disable_object(struct klp_object *obj) |
b700e7f0 SJ |
449 | { |
450 | struct klp_func *func; | |
b700e7f0 | 451 | |
8cdd043a | 452 | klp_for_each_func(obj, func) |
0937e3b0 JP |
453 | if (func->state == KLP_ENABLED) |
454 | klp_disable_func(func); | |
b700e7f0 SJ |
455 | |
456 | obj->state = KLP_DISABLED; | |
b700e7f0 SJ |
457 | } |
458 | ||
459 | static int klp_enable_object(struct klp_object *obj) | |
460 | { | |
461 | struct klp_func *func; | |
462 | int ret; | |
463 | ||
464 | if (WARN_ON(obj->state != KLP_DISABLED)) | |
465 | return -EINVAL; | |
466 | ||
467 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
468 | return -EINVAL; | |
469 | ||
8cdd043a | 470 | klp_for_each_func(obj, func) { |
b700e7f0 | 471 | ret = klp_enable_func(func); |
0937e3b0 JP |
472 | if (ret) { |
473 | klp_disable_object(obj); | |
474 | return ret; | |
475 | } | |
b700e7f0 SJ |
476 | } |
477 | obj->state = KLP_ENABLED; | |
478 | ||
479 | return 0; | |
b700e7f0 SJ |
480 | } |
481 | ||
482 | static int __klp_disable_patch(struct klp_patch *patch) | |
483 | { | |
484 | struct klp_object *obj; | |
b700e7f0 | 485 | |
83a90bb1 JP |
486 | /* enforce stacking: only the last enabled patch can be disabled */ |
487 | if (!list_is_last(&patch->list, &klp_patches) && | |
488 | list_next_entry(patch, list)->state == KLP_ENABLED) | |
489 | return -EBUSY; | |
490 | ||
b700e7f0 SJ |
491 | pr_notice("disabling patch '%s'\n", patch->mod->name); |
492 | ||
8cdd043a | 493 | klp_for_each_object(patch, obj) { |
0937e3b0 JP |
494 | if (obj->state == KLP_ENABLED) |
495 | klp_disable_object(obj); | |
b700e7f0 SJ |
496 | } |
497 | ||
498 | patch->state = KLP_DISABLED; | |
499 | ||
500 | return 0; | |
501 | } | |
502 | ||
503 | /** | |
504 | * klp_disable_patch() - disables a registered patch | |
505 | * @patch: The registered, enabled patch to be disabled | |
506 | * | |
507 | * Unregisters the patched functions from ftrace. | |
508 | * | |
509 | * Return: 0 on success, otherwise error | |
510 | */ | |
511 | int klp_disable_patch(struct klp_patch *patch) | |
512 | { | |
513 | int ret; | |
514 | ||
515 | mutex_lock(&klp_mutex); | |
516 | ||
517 | if (!klp_is_patch_registered(patch)) { | |
518 | ret = -EINVAL; | |
519 | goto err; | |
520 | } | |
521 | ||
522 | if (patch->state == KLP_DISABLED) { | |
523 | ret = -EINVAL; | |
524 | goto err; | |
525 | } | |
526 | ||
527 | ret = __klp_disable_patch(patch); | |
528 | ||
529 | err: | |
530 | mutex_unlock(&klp_mutex); | |
531 | return ret; | |
532 | } | |
533 | EXPORT_SYMBOL_GPL(klp_disable_patch); | |
534 | ||
535 | static int __klp_enable_patch(struct klp_patch *patch) | |
536 | { | |
537 | struct klp_object *obj; | |
538 | int ret; | |
539 | ||
540 | if (WARN_ON(patch->state != KLP_DISABLED)) | |
541 | return -EINVAL; | |
542 | ||
83a90bb1 JP |
543 | /* enforce stacking: only the first disabled patch can be enabled */ |
544 | if (patch->list.prev != &klp_patches && | |
545 | list_prev_entry(patch, list)->state == KLP_DISABLED) | |
546 | return -EBUSY; | |
547 | ||
b700e7f0 SJ |
548 | pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n"); |
549 | add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK); | |
550 | ||
551 | pr_notice("enabling patch '%s'\n", patch->mod->name); | |
552 | ||
8cdd043a | 553 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
554 | if (!klp_is_object_loaded(obj)) |
555 | continue; | |
556 | ||
557 | ret = klp_enable_object(obj); | |
558 | if (ret) | |
559 | goto unregister; | |
560 | } | |
561 | ||
562 | patch->state = KLP_ENABLED; | |
563 | ||
564 | return 0; | |
565 | ||
566 | unregister: | |
567 | WARN_ON(__klp_disable_patch(patch)); | |
568 | return ret; | |
569 | } | |
570 | ||
571 | /** | |
572 | * klp_enable_patch() - enables a registered patch | |
573 | * @patch: The registered, disabled patch to be enabled | |
574 | * | |
575 | * Performs the needed symbol lookups and code relocations, | |
576 | * then registers the patched functions with ftrace. | |
577 | * | |
578 | * Return: 0 on success, otherwise error | |
579 | */ | |
580 | int klp_enable_patch(struct klp_patch *patch) | |
581 | { | |
582 | int ret; | |
583 | ||
584 | mutex_lock(&klp_mutex); | |
585 | ||
586 | if (!klp_is_patch_registered(patch)) { | |
587 | ret = -EINVAL; | |
588 | goto err; | |
589 | } | |
590 | ||
591 | ret = __klp_enable_patch(patch); | |
592 | ||
593 | err: | |
594 | mutex_unlock(&klp_mutex); | |
595 | return ret; | |
596 | } | |
597 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
598 | ||
599 | /* | |
600 | * Sysfs Interface | |
601 | * | |
602 | * /sys/kernel/livepatch | |
603 | * /sys/kernel/livepatch/<patch> | |
604 | * /sys/kernel/livepatch/<patch>/enabled | |
605 | * /sys/kernel/livepatch/<patch>/<object> | |
444f9e99 | 606 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 SJ |
607 | */ |
608 | ||
609 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
610 | const char *buf, size_t count) | |
611 | { | |
612 | struct klp_patch *patch; | |
613 | int ret; | |
614 | unsigned long val; | |
615 | ||
616 | ret = kstrtoul(buf, 10, &val); | |
617 | if (ret) | |
618 | return -EINVAL; | |
619 | ||
620 | if (val != KLP_DISABLED && val != KLP_ENABLED) | |
621 | return -EINVAL; | |
622 | ||
623 | patch = container_of(kobj, struct klp_patch, kobj); | |
624 | ||
625 | mutex_lock(&klp_mutex); | |
626 | ||
627 | if (val == patch->state) { | |
628 | /* already in requested state */ | |
629 | ret = -EINVAL; | |
630 | goto err; | |
631 | } | |
632 | ||
633 | if (val == KLP_ENABLED) { | |
634 | ret = __klp_enable_patch(patch); | |
635 | if (ret) | |
636 | goto err; | |
637 | } else { | |
638 | ret = __klp_disable_patch(patch); | |
639 | if (ret) | |
640 | goto err; | |
641 | } | |
642 | ||
643 | mutex_unlock(&klp_mutex); | |
644 | ||
645 | return count; | |
646 | ||
647 | err: | |
648 | mutex_unlock(&klp_mutex); | |
649 | return ret; | |
650 | } | |
651 | ||
652 | static ssize_t enabled_show(struct kobject *kobj, | |
653 | struct kobj_attribute *attr, char *buf) | |
654 | { | |
655 | struct klp_patch *patch; | |
656 | ||
657 | patch = container_of(kobj, struct klp_patch, kobj); | |
658 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->state); | |
659 | } | |
660 | ||
661 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); | |
662 | static struct attribute *klp_patch_attrs[] = { | |
663 | &enabled_kobj_attr.attr, | |
664 | NULL | |
665 | }; | |
666 | ||
667 | static void klp_kobj_release_patch(struct kobject *kobj) | |
668 | { | |
669 | /* | |
670 | * Once we have a consistency model we'll need to module_put() the | |
671 | * patch module here. See klp_register_patch() for more details. | |
672 | */ | |
673 | } | |
674 | ||
675 | static struct kobj_type klp_ktype_patch = { | |
676 | .release = klp_kobj_release_patch, | |
677 | .sysfs_ops = &kobj_sysfs_ops, | |
678 | .default_attrs = klp_patch_attrs, | |
679 | }; | |
680 | ||
cad706df MB |
681 | static void klp_kobj_release_object(struct kobject *kobj) |
682 | { | |
683 | } | |
684 | ||
685 | static struct kobj_type klp_ktype_object = { | |
686 | .release = klp_kobj_release_object, | |
687 | .sysfs_ops = &kobj_sysfs_ops, | |
688 | }; | |
689 | ||
b700e7f0 SJ |
690 | static void klp_kobj_release_func(struct kobject *kobj) |
691 | { | |
b700e7f0 SJ |
692 | } |
693 | ||
694 | static struct kobj_type klp_ktype_func = { | |
695 | .release = klp_kobj_release_func, | |
696 | .sysfs_ops = &kobj_sysfs_ops, | |
697 | }; | |
698 | ||
699 | /* | |
700 | * Free all functions' kobjects in the array up to some limit. When limit is | |
701 | * NULL, all kobjects are freed. | |
702 | */ | |
703 | static void klp_free_funcs_limited(struct klp_object *obj, | |
704 | struct klp_func *limit) | |
705 | { | |
706 | struct klp_func *func; | |
707 | ||
708 | for (func = obj->funcs; func->old_name && func != limit; func++) | |
709 | kobject_put(&func->kobj); | |
710 | } | |
711 | ||
712 | /* Clean up when a patched object is unloaded */ | |
713 | static void klp_free_object_loaded(struct klp_object *obj) | |
714 | { | |
715 | struct klp_func *func; | |
716 | ||
717 | obj->mod = NULL; | |
718 | ||
8cdd043a | 719 | klp_for_each_func(obj, func) |
b700e7f0 SJ |
720 | func->old_addr = 0; |
721 | } | |
722 | ||
723 | /* | |
724 | * Free all objects' kobjects in the array up to some limit. When limit is | |
725 | * NULL, all kobjects are freed. | |
726 | */ | |
727 | static void klp_free_objects_limited(struct klp_patch *patch, | |
728 | struct klp_object *limit) | |
729 | { | |
730 | struct klp_object *obj; | |
731 | ||
732 | for (obj = patch->objs; obj->funcs && obj != limit; obj++) { | |
733 | klp_free_funcs_limited(obj, NULL); | |
cad706df | 734 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
735 | } |
736 | } | |
737 | ||
738 | static void klp_free_patch(struct klp_patch *patch) | |
739 | { | |
740 | klp_free_objects_limited(patch, NULL); | |
741 | if (!list_empty(&patch->list)) | |
742 | list_del(&patch->list); | |
743 | kobject_put(&patch->kobj); | |
744 | } | |
745 | ||
746 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
747 | { | |
f09d9086 MB |
748 | if (!func->old_name || !func->new_func) |
749 | return -EINVAL; | |
750 | ||
3c33f5b9 | 751 | INIT_LIST_HEAD(&func->stack_node); |
b700e7f0 SJ |
752 | func->state = KLP_DISABLED; |
753 | ||
444f9e99 CA |
754 | /* The format for the sysfs directory is <function,sympos> where sympos |
755 | * is the nth occurrence of this symbol in kallsyms for the patched | |
756 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
757 | * since a unique symbol will be the first occurrence. | |
758 | */ | |
3c33f5b9 | 759 | return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
444f9e99 CA |
760 | &obj->kobj, "%s,%lu", func->old_name, |
761 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
762 | } |
763 | ||
255e732c JY |
764 | /* Arches may override this to finish any remaining arch-specific tasks */ |
765 | void __weak arch_klp_init_object_loaded(struct klp_patch *patch, | |
766 | struct klp_object *obj) | |
767 | { | |
768 | } | |
769 | ||
b700e7f0 SJ |
770 | /* parts of the initialization that is done only when the object is loaded */ |
771 | static int klp_init_object_loaded(struct klp_patch *patch, | |
772 | struct klp_object *obj) | |
773 | { | |
774 | struct klp_func *func; | |
775 | int ret; | |
776 | ||
255e732c | 777 | module_disable_ro(patch->mod); |
425595a7 | 778 | ret = klp_write_object_relocations(patch->mod, obj); |
255e732c JY |
779 | if (ret) { |
780 | module_enable_ro(patch->mod, true); | |
425595a7 | 781 | return ret; |
255e732c JY |
782 | } |
783 | ||
784 | arch_klp_init_object_loaded(patch, obj); | |
785 | module_enable_ro(patch->mod, true); | |
b700e7f0 | 786 | |
8cdd043a | 787 | klp_for_each_func(obj, func) { |
b2b018ef CA |
788 | ret = klp_find_object_symbol(obj->name, func->old_name, |
789 | func->old_sympos, | |
790 | &func->old_addr); | |
b700e7f0 SJ |
791 | if (ret) |
792 | return ret; | |
793 | } | |
794 | ||
795 | return 0; | |
796 | } | |
797 | ||
798 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
799 | { | |
800 | struct klp_func *func; | |
801 | int ret; | |
802 | const char *name; | |
803 | ||
804 | if (!obj->funcs) | |
805 | return -EINVAL; | |
806 | ||
807 | obj->state = KLP_DISABLED; | |
8cb2c2dc | 808 | obj->mod = NULL; |
b700e7f0 SJ |
809 | |
810 | klp_find_object_module(obj); | |
811 | ||
812 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
cad706df MB |
813 | ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object, |
814 | &patch->kobj, "%s", name); | |
815 | if (ret) | |
816 | return ret; | |
b700e7f0 | 817 | |
8cdd043a | 818 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
819 | ret = klp_init_func(obj, func); |
820 | if (ret) | |
821 | goto free; | |
822 | } | |
823 | ||
824 | if (klp_is_object_loaded(obj)) { | |
825 | ret = klp_init_object_loaded(patch, obj); | |
826 | if (ret) | |
827 | goto free; | |
828 | } | |
829 | ||
830 | return 0; | |
831 | ||
832 | free: | |
833 | klp_free_funcs_limited(obj, func); | |
cad706df | 834 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
835 | return ret; |
836 | } | |
837 | ||
838 | static int klp_init_patch(struct klp_patch *patch) | |
839 | { | |
840 | struct klp_object *obj; | |
841 | int ret; | |
842 | ||
843 | if (!patch->objs) | |
844 | return -EINVAL; | |
845 | ||
846 | mutex_lock(&klp_mutex); | |
847 | ||
848 | patch->state = KLP_DISABLED; | |
849 | ||
850 | ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, | |
e0b561ee | 851 | klp_root_kobj, "%s", patch->mod->name); |
b700e7f0 SJ |
852 | if (ret) |
853 | goto unlock; | |
854 | ||
8cdd043a | 855 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
856 | ret = klp_init_object(patch, obj); |
857 | if (ret) | |
858 | goto free; | |
859 | } | |
860 | ||
99590ba5 | 861 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
862 | |
863 | mutex_unlock(&klp_mutex); | |
864 | ||
865 | return 0; | |
866 | ||
867 | free: | |
868 | klp_free_objects_limited(patch, obj); | |
869 | kobject_put(&patch->kobj); | |
870 | unlock: | |
871 | mutex_unlock(&klp_mutex); | |
872 | return ret; | |
873 | } | |
874 | ||
875 | /** | |
876 | * klp_unregister_patch() - unregisters a patch | |
877 | * @patch: Disabled patch to be unregistered | |
878 | * | |
879 | * Frees the data structures and removes the sysfs interface. | |
880 | * | |
881 | * Return: 0 on success, otherwise error | |
882 | */ | |
883 | int klp_unregister_patch(struct klp_patch *patch) | |
884 | { | |
885 | int ret = 0; | |
886 | ||
887 | mutex_lock(&klp_mutex); | |
888 | ||
889 | if (!klp_is_patch_registered(patch)) { | |
890 | ret = -EINVAL; | |
891 | goto out; | |
892 | } | |
893 | ||
894 | if (patch->state == KLP_ENABLED) { | |
895 | ret = -EBUSY; | |
896 | goto out; | |
897 | } | |
898 | ||
899 | klp_free_patch(patch); | |
900 | ||
901 | out: | |
902 | mutex_unlock(&klp_mutex); | |
903 | return ret; | |
904 | } | |
905 | EXPORT_SYMBOL_GPL(klp_unregister_patch); | |
906 | ||
907 | /** | |
908 | * klp_register_patch() - registers a patch | |
909 | * @patch: Patch to be registered | |
910 | * | |
911 | * Initializes the data structure associated with the patch and | |
912 | * creates the sysfs interface. | |
913 | * | |
914 | * Return: 0 on success, otherwise error | |
915 | */ | |
916 | int klp_register_patch(struct klp_patch *patch) | |
917 | { | |
918 | int ret; | |
919 | ||
b700e7f0 SJ |
920 | if (!patch || !patch->mod) |
921 | return -EINVAL; | |
922 | ||
425595a7 JY |
923 | if (!is_livepatch_module(patch->mod)) { |
924 | pr_err("module %s is not marked as a livepatch module", | |
925 | patch->mod->name); | |
926 | return -EINVAL; | |
927 | } | |
928 | ||
b700e7f0 SJ |
929 | if (!klp_initialized()) |
930 | return -ENODEV; | |
931 | ||
b700e7f0 SJ |
932 | /* |
933 | * A reference is taken on the patch module to prevent it from being | |
934 | * unloaded. Right now, we don't allow patch modules to unload since | |
935 | * there is currently no method to determine if a thread is still | |
936 | * running in the patched code contained in the patch module once | |
937 | * the ftrace registration is successful. | |
938 | */ | |
939 | if (!try_module_get(patch->mod)) | |
940 | return -ENODEV; | |
941 | ||
942 | ret = klp_init_patch(patch); | |
943 | if (ret) | |
944 | module_put(patch->mod); | |
945 | ||
946 | return ret; | |
947 | } | |
948 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
949 | ||
7e545d6e | 950 | int klp_module_coming(struct module *mod) |
b700e7f0 | 951 | { |
b700e7f0 | 952 | int ret; |
7e545d6e JY |
953 | struct klp_patch *patch; |
954 | struct klp_object *obj; | |
b700e7f0 | 955 | |
7e545d6e JY |
956 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
957 | return -EINVAL; | |
b700e7f0 | 958 | |
7e545d6e JY |
959 | mutex_lock(&klp_mutex); |
960 | /* | |
961 | * Each module has to know that klp_module_coming() | |
962 | * has been called. We never know what module will | |
963 | * get patched by a new patch. | |
964 | */ | |
965 | mod->klp_alive = true; | |
b700e7f0 | 966 | |
7e545d6e JY |
967 | list_for_each_entry(patch, &klp_patches, list) { |
968 | klp_for_each_object(patch, obj) { | |
969 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
970 | continue; | |
b700e7f0 | 971 | |
7e545d6e | 972 | obj->mod = mod; |
b700e7f0 | 973 | |
7e545d6e JY |
974 | ret = klp_init_object_loaded(patch, obj); |
975 | if (ret) { | |
976 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
977 | patch->mod->name, obj->mod->name, ret); | |
978 | goto err; | |
979 | } | |
b700e7f0 | 980 | |
7e545d6e JY |
981 | if (patch->state == KLP_DISABLED) |
982 | break; | |
983 | ||
984 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
985 | patch->mod->name, obj->mod->name); | |
986 | ||
987 | ret = klp_enable_object(obj); | |
988 | if (ret) { | |
989 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
990 | patch->mod->name, obj->mod->name, ret); | |
991 | goto err; | |
992 | } | |
993 | ||
994 | break; | |
995 | } | |
996 | } | |
b700e7f0 | 997 | |
7e545d6e | 998 | mutex_unlock(&klp_mutex); |
b700e7f0 | 999 | |
7e545d6e | 1000 | return 0; |
b700e7f0 | 1001 | |
7e545d6e JY |
1002 | err: |
1003 | /* | |
1004 | * If a patch is unsuccessfully applied, return | |
1005 | * error to the module loader. | |
1006 | */ | |
1007 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
1008 | patch->mod->name, obj->mod->name, obj->mod->name); | |
1009 | mod->klp_alive = false; | |
b700e7f0 | 1010 | klp_free_object_loaded(obj); |
7e545d6e JY |
1011 | mutex_unlock(&klp_mutex); |
1012 | ||
1013 | return ret; | |
b700e7f0 SJ |
1014 | } |
1015 | ||
7e545d6e | 1016 | void klp_module_going(struct module *mod) |
b700e7f0 | 1017 | { |
b700e7f0 SJ |
1018 | struct klp_patch *patch; |
1019 | struct klp_object *obj; | |
1020 | ||
7e545d6e JY |
1021 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1022 | mod->state != MODULE_STATE_COMING)) | |
1023 | return; | |
b700e7f0 SJ |
1024 | |
1025 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1026 | /* |
7e545d6e JY |
1027 | * Each module has to know that klp_module_going() |
1028 | * has been called. We never know what module will | |
1029 | * get patched by a new patch. | |
8cb2c2dc | 1030 | */ |
7e545d6e | 1031 | mod->klp_alive = false; |
8cb2c2dc | 1032 | |
b700e7f0 | 1033 | list_for_each_entry(patch, &klp_patches, list) { |
8cdd043a | 1034 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
1035 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) |
1036 | continue; | |
1037 | ||
7e545d6e JY |
1038 | if (patch->state != KLP_DISABLED) { |
1039 | pr_notice("reverting patch '%s' on unloading module '%s'\n", | |
1040 | patch->mod->name, obj->mod->name); | |
1041 | klp_disable_object(obj); | |
1042 | } | |
b700e7f0 | 1043 | |
7e545d6e | 1044 | klp_free_object_loaded(obj); |
b700e7f0 SJ |
1045 | break; |
1046 | } | |
1047 | } | |
1048 | ||
1049 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1050 | } |
1051 | ||
26029d88 | 1052 | static int __init klp_init(void) |
b700e7f0 SJ |
1053 | { |
1054 | int ret; | |
1055 | ||
b9dfe0be JK |
1056 | ret = klp_check_compiler_support(); |
1057 | if (ret) { | |
1058 | pr_info("Your compiler is too old; turning off.\n"); | |
1059 | return -EINVAL; | |
1060 | } | |
1061 | ||
b700e7f0 | 1062 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1063 | if (!klp_root_kobj) |
1064 | return -ENOMEM; | |
b700e7f0 SJ |
1065 | |
1066 | return 0; | |
b700e7f0 SJ |
1067 | } |
1068 | ||
1069 | module_init(klp_init); |