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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("enabling patch '%s'\n", patch->mod->name); |
549 | ||
8cdd043a | 550 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
551 | if (!klp_is_object_loaded(obj)) |
552 | continue; | |
553 | ||
554 | ret = klp_enable_object(obj); | |
555 | if (ret) | |
556 | goto unregister; | |
557 | } | |
558 | ||
559 | patch->state = KLP_ENABLED; | |
560 | ||
561 | return 0; | |
562 | ||
563 | unregister: | |
564 | WARN_ON(__klp_disable_patch(patch)); | |
565 | return ret; | |
566 | } | |
567 | ||
568 | /** | |
569 | * klp_enable_patch() - enables a registered patch | |
570 | * @patch: The registered, disabled patch to be enabled | |
571 | * | |
572 | * Performs the needed symbol lookups and code relocations, | |
573 | * then registers the patched functions with ftrace. | |
574 | * | |
575 | * Return: 0 on success, otherwise error | |
576 | */ | |
577 | int klp_enable_patch(struct klp_patch *patch) | |
578 | { | |
579 | int ret; | |
580 | ||
581 | mutex_lock(&klp_mutex); | |
582 | ||
583 | if (!klp_is_patch_registered(patch)) { | |
584 | ret = -EINVAL; | |
585 | goto err; | |
586 | } | |
587 | ||
588 | ret = __klp_enable_patch(patch); | |
589 | ||
590 | err: | |
591 | mutex_unlock(&klp_mutex); | |
592 | return ret; | |
593 | } | |
594 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
595 | ||
596 | /* | |
597 | * Sysfs Interface | |
598 | * | |
599 | * /sys/kernel/livepatch | |
600 | * /sys/kernel/livepatch/<patch> | |
601 | * /sys/kernel/livepatch/<patch>/enabled | |
602 | * /sys/kernel/livepatch/<patch>/<object> | |
444f9e99 | 603 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 SJ |
604 | */ |
605 | ||
606 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
607 | const char *buf, size_t count) | |
608 | { | |
609 | struct klp_patch *patch; | |
610 | int ret; | |
611 | unsigned long val; | |
612 | ||
613 | ret = kstrtoul(buf, 10, &val); | |
614 | if (ret) | |
615 | return -EINVAL; | |
616 | ||
617 | if (val != KLP_DISABLED && val != KLP_ENABLED) | |
618 | return -EINVAL; | |
619 | ||
620 | patch = container_of(kobj, struct klp_patch, kobj); | |
621 | ||
622 | mutex_lock(&klp_mutex); | |
623 | ||
624 | if (val == patch->state) { | |
625 | /* already in requested state */ | |
626 | ret = -EINVAL; | |
627 | goto err; | |
628 | } | |
629 | ||
630 | if (val == KLP_ENABLED) { | |
631 | ret = __klp_enable_patch(patch); | |
632 | if (ret) | |
633 | goto err; | |
634 | } else { | |
635 | ret = __klp_disable_patch(patch); | |
636 | if (ret) | |
637 | goto err; | |
638 | } | |
639 | ||
640 | mutex_unlock(&klp_mutex); | |
641 | ||
642 | return count; | |
643 | ||
644 | err: | |
645 | mutex_unlock(&klp_mutex); | |
646 | return ret; | |
647 | } | |
648 | ||
649 | static ssize_t enabled_show(struct kobject *kobj, | |
650 | struct kobj_attribute *attr, char *buf) | |
651 | { | |
652 | struct klp_patch *patch; | |
653 | ||
654 | patch = container_of(kobj, struct klp_patch, kobj); | |
655 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->state); | |
656 | } | |
657 | ||
658 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); | |
659 | static struct attribute *klp_patch_attrs[] = { | |
660 | &enabled_kobj_attr.attr, | |
661 | NULL | |
662 | }; | |
663 | ||
664 | static void klp_kobj_release_patch(struct kobject *kobj) | |
665 | { | |
666 | /* | |
667 | * Once we have a consistency model we'll need to module_put() the | |
668 | * patch module here. See klp_register_patch() for more details. | |
669 | */ | |
670 | } | |
671 | ||
672 | static struct kobj_type klp_ktype_patch = { | |
673 | .release = klp_kobj_release_patch, | |
674 | .sysfs_ops = &kobj_sysfs_ops, | |
675 | .default_attrs = klp_patch_attrs, | |
676 | }; | |
677 | ||
cad706df MB |
678 | static void klp_kobj_release_object(struct kobject *kobj) |
679 | { | |
680 | } | |
681 | ||
682 | static struct kobj_type klp_ktype_object = { | |
683 | .release = klp_kobj_release_object, | |
684 | .sysfs_ops = &kobj_sysfs_ops, | |
685 | }; | |
686 | ||
b700e7f0 SJ |
687 | static void klp_kobj_release_func(struct kobject *kobj) |
688 | { | |
b700e7f0 SJ |
689 | } |
690 | ||
691 | static struct kobj_type klp_ktype_func = { | |
692 | .release = klp_kobj_release_func, | |
693 | .sysfs_ops = &kobj_sysfs_ops, | |
694 | }; | |
695 | ||
696 | /* | |
697 | * Free all functions' kobjects in the array up to some limit. When limit is | |
698 | * NULL, all kobjects are freed. | |
699 | */ | |
700 | static void klp_free_funcs_limited(struct klp_object *obj, | |
701 | struct klp_func *limit) | |
702 | { | |
703 | struct klp_func *func; | |
704 | ||
705 | for (func = obj->funcs; func->old_name && func != limit; func++) | |
706 | kobject_put(&func->kobj); | |
707 | } | |
708 | ||
709 | /* Clean up when a patched object is unloaded */ | |
710 | static void klp_free_object_loaded(struct klp_object *obj) | |
711 | { | |
712 | struct klp_func *func; | |
713 | ||
714 | obj->mod = NULL; | |
715 | ||
8cdd043a | 716 | klp_for_each_func(obj, func) |
b700e7f0 SJ |
717 | func->old_addr = 0; |
718 | } | |
719 | ||
720 | /* | |
721 | * Free all objects' kobjects in the array up to some limit. When limit is | |
722 | * NULL, all kobjects are freed. | |
723 | */ | |
724 | static void klp_free_objects_limited(struct klp_patch *patch, | |
725 | struct klp_object *limit) | |
726 | { | |
727 | struct klp_object *obj; | |
728 | ||
729 | for (obj = patch->objs; obj->funcs && obj != limit; obj++) { | |
730 | klp_free_funcs_limited(obj, NULL); | |
cad706df | 731 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
732 | } |
733 | } | |
734 | ||
735 | static void klp_free_patch(struct klp_patch *patch) | |
736 | { | |
737 | klp_free_objects_limited(patch, NULL); | |
738 | if (!list_empty(&patch->list)) | |
739 | list_del(&patch->list); | |
740 | kobject_put(&patch->kobj); | |
741 | } | |
742 | ||
743 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
744 | { | |
f09d9086 MB |
745 | if (!func->old_name || !func->new_func) |
746 | return -EINVAL; | |
747 | ||
3c33f5b9 | 748 | INIT_LIST_HEAD(&func->stack_node); |
b700e7f0 SJ |
749 | func->state = KLP_DISABLED; |
750 | ||
444f9e99 CA |
751 | /* The format for the sysfs directory is <function,sympos> where sympos |
752 | * is the nth occurrence of this symbol in kallsyms for the patched | |
753 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
754 | * since a unique symbol will be the first occurrence. | |
755 | */ | |
3c33f5b9 | 756 | return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
444f9e99 CA |
757 | &obj->kobj, "%s,%lu", func->old_name, |
758 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
759 | } |
760 | ||
255e732c JY |
761 | /* Arches may override this to finish any remaining arch-specific tasks */ |
762 | void __weak arch_klp_init_object_loaded(struct klp_patch *patch, | |
763 | struct klp_object *obj) | |
764 | { | |
765 | } | |
766 | ||
b700e7f0 SJ |
767 | /* parts of the initialization that is done only when the object is loaded */ |
768 | static int klp_init_object_loaded(struct klp_patch *patch, | |
769 | struct klp_object *obj) | |
770 | { | |
771 | struct klp_func *func; | |
772 | int ret; | |
773 | ||
255e732c | 774 | module_disable_ro(patch->mod); |
425595a7 | 775 | ret = klp_write_object_relocations(patch->mod, obj); |
255e732c JY |
776 | if (ret) { |
777 | module_enable_ro(patch->mod, true); | |
425595a7 | 778 | return ret; |
255e732c JY |
779 | } |
780 | ||
781 | arch_klp_init_object_loaded(patch, obj); | |
782 | module_enable_ro(patch->mod, true); | |
b700e7f0 | 783 | |
8cdd043a | 784 | klp_for_each_func(obj, func) { |
b2b018ef CA |
785 | ret = klp_find_object_symbol(obj->name, func->old_name, |
786 | func->old_sympos, | |
787 | &func->old_addr); | |
b700e7f0 SJ |
788 | if (ret) |
789 | return ret; | |
790 | } | |
791 | ||
792 | return 0; | |
793 | } | |
794 | ||
795 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
796 | { | |
797 | struct klp_func *func; | |
798 | int ret; | |
799 | const char *name; | |
800 | ||
801 | if (!obj->funcs) | |
802 | return -EINVAL; | |
803 | ||
804 | obj->state = KLP_DISABLED; | |
8cb2c2dc | 805 | obj->mod = NULL; |
b700e7f0 SJ |
806 | |
807 | klp_find_object_module(obj); | |
808 | ||
809 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
cad706df MB |
810 | ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object, |
811 | &patch->kobj, "%s", name); | |
812 | if (ret) | |
813 | return ret; | |
b700e7f0 | 814 | |
8cdd043a | 815 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
816 | ret = klp_init_func(obj, func); |
817 | if (ret) | |
818 | goto free; | |
819 | } | |
820 | ||
821 | if (klp_is_object_loaded(obj)) { | |
822 | ret = klp_init_object_loaded(patch, obj); | |
823 | if (ret) | |
824 | goto free; | |
825 | } | |
826 | ||
827 | return 0; | |
828 | ||
829 | free: | |
830 | klp_free_funcs_limited(obj, func); | |
cad706df | 831 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
832 | return ret; |
833 | } | |
834 | ||
835 | static int klp_init_patch(struct klp_patch *patch) | |
836 | { | |
837 | struct klp_object *obj; | |
838 | int ret; | |
839 | ||
840 | if (!patch->objs) | |
841 | return -EINVAL; | |
842 | ||
843 | mutex_lock(&klp_mutex); | |
844 | ||
845 | patch->state = KLP_DISABLED; | |
846 | ||
847 | ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, | |
e0b561ee | 848 | klp_root_kobj, "%s", patch->mod->name); |
b700e7f0 SJ |
849 | if (ret) |
850 | goto unlock; | |
851 | ||
8cdd043a | 852 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
853 | ret = klp_init_object(patch, obj); |
854 | if (ret) | |
855 | goto free; | |
856 | } | |
857 | ||
99590ba5 | 858 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
859 | |
860 | mutex_unlock(&klp_mutex); | |
861 | ||
862 | return 0; | |
863 | ||
864 | free: | |
865 | klp_free_objects_limited(patch, obj); | |
866 | kobject_put(&patch->kobj); | |
867 | unlock: | |
868 | mutex_unlock(&klp_mutex); | |
869 | return ret; | |
870 | } | |
871 | ||
872 | /** | |
873 | * klp_unregister_patch() - unregisters a patch | |
874 | * @patch: Disabled patch to be unregistered | |
875 | * | |
876 | * Frees the data structures and removes the sysfs interface. | |
877 | * | |
878 | * Return: 0 on success, otherwise error | |
879 | */ | |
880 | int klp_unregister_patch(struct klp_patch *patch) | |
881 | { | |
882 | int ret = 0; | |
883 | ||
884 | mutex_lock(&klp_mutex); | |
885 | ||
886 | if (!klp_is_patch_registered(patch)) { | |
887 | ret = -EINVAL; | |
888 | goto out; | |
889 | } | |
890 | ||
891 | if (patch->state == KLP_ENABLED) { | |
892 | ret = -EBUSY; | |
893 | goto out; | |
894 | } | |
895 | ||
896 | klp_free_patch(patch); | |
897 | ||
898 | out: | |
899 | mutex_unlock(&klp_mutex); | |
900 | return ret; | |
901 | } | |
902 | EXPORT_SYMBOL_GPL(klp_unregister_patch); | |
903 | ||
904 | /** | |
905 | * klp_register_patch() - registers a patch | |
906 | * @patch: Patch to be registered | |
907 | * | |
908 | * Initializes the data structure associated with the patch and | |
909 | * creates the sysfs interface. | |
910 | * | |
911 | * Return: 0 on success, otherwise error | |
912 | */ | |
913 | int klp_register_patch(struct klp_patch *patch) | |
914 | { | |
915 | int ret; | |
916 | ||
b700e7f0 SJ |
917 | if (!patch || !patch->mod) |
918 | return -EINVAL; | |
919 | ||
425595a7 JY |
920 | if (!is_livepatch_module(patch->mod)) { |
921 | pr_err("module %s is not marked as a livepatch module", | |
922 | patch->mod->name); | |
923 | return -EINVAL; | |
924 | } | |
925 | ||
b700e7f0 SJ |
926 | if (!klp_initialized()) |
927 | return -ENODEV; | |
928 | ||
b700e7f0 SJ |
929 | /* |
930 | * A reference is taken on the patch module to prevent it from being | |
931 | * unloaded. Right now, we don't allow patch modules to unload since | |
932 | * there is currently no method to determine if a thread is still | |
933 | * running in the patched code contained in the patch module once | |
934 | * the ftrace registration is successful. | |
935 | */ | |
936 | if (!try_module_get(patch->mod)) | |
937 | return -ENODEV; | |
938 | ||
939 | ret = klp_init_patch(patch); | |
940 | if (ret) | |
941 | module_put(patch->mod); | |
942 | ||
943 | return ret; | |
944 | } | |
945 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
946 | ||
7e545d6e | 947 | int klp_module_coming(struct module *mod) |
b700e7f0 | 948 | { |
b700e7f0 | 949 | int ret; |
7e545d6e JY |
950 | struct klp_patch *patch; |
951 | struct klp_object *obj; | |
b700e7f0 | 952 | |
7e545d6e JY |
953 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
954 | return -EINVAL; | |
b700e7f0 | 955 | |
7e545d6e JY |
956 | mutex_lock(&klp_mutex); |
957 | /* | |
958 | * Each module has to know that klp_module_coming() | |
959 | * has been called. We never know what module will | |
960 | * get patched by a new patch. | |
961 | */ | |
962 | mod->klp_alive = true; | |
b700e7f0 | 963 | |
7e545d6e JY |
964 | list_for_each_entry(patch, &klp_patches, list) { |
965 | klp_for_each_object(patch, obj) { | |
966 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
967 | continue; | |
b700e7f0 | 968 | |
7e545d6e | 969 | obj->mod = mod; |
b700e7f0 | 970 | |
7e545d6e JY |
971 | ret = klp_init_object_loaded(patch, obj); |
972 | if (ret) { | |
973 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
974 | patch->mod->name, obj->mod->name, ret); | |
975 | goto err; | |
976 | } | |
b700e7f0 | 977 | |
7e545d6e JY |
978 | if (patch->state == KLP_DISABLED) |
979 | break; | |
980 | ||
981 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
982 | patch->mod->name, obj->mod->name); | |
983 | ||
984 | ret = klp_enable_object(obj); | |
985 | if (ret) { | |
986 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
987 | patch->mod->name, obj->mod->name, ret); | |
988 | goto err; | |
989 | } | |
990 | ||
991 | break; | |
992 | } | |
993 | } | |
b700e7f0 | 994 | |
7e545d6e | 995 | mutex_unlock(&klp_mutex); |
b700e7f0 | 996 | |
7e545d6e | 997 | return 0; |
b700e7f0 | 998 | |
7e545d6e JY |
999 | err: |
1000 | /* | |
1001 | * If a patch is unsuccessfully applied, return | |
1002 | * error to the module loader. | |
1003 | */ | |
1004 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
1005 | patch->mod->name, obj->mod->name, obj->mod->name); | |
1006 | mod->klp_alive = false; | |
b700e7f0 | 1007 | klp_free_object_loaded(obj); |
7e545d6e JY |
1008 | mutex_unlock(&klp_mutex); |
1009 | ||
1010 | return ret; | |
b700e7f0 SJ |
1011 | } |
1012 | ||
7e545d6e | 1013 | void klp_module_going(struct module *mod) |
b700e7f0 | 1014 | { |
b700e7f0 SJ |
1015 | struct klp_patch *patch; |
1016 | struct klp_object *obj; | |
1017 | ||
7e545d6e JY |
1018 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1019 | mod->state != MODULE_STATE_COMING)) | |
1020 | return; | |
b700e7f0 SJ |
1021 | |
1022 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1023 | /* |
7e545d6e JY |
1024 | * Each module has to know that klp_module_going() |
1025 | * has been called. We never know what module will | |
1026 | * get patched by a new patch. | |
8cb2c2dc | 1027 | */ |
7e545d6e | 1028 | mod->klp_alive = false; |
8cb2c2dc | 1029 | |
b700e7f0 | 1030 | list_for_each_entry(patch, &klp_patches, list) { |
8cdd043a | 1031 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
1032 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) |
1033 | continue; | |
1034 | ||
7e545d6e JY |
1035 | if (patch->state != KLP_DISABLED) { |
1036 | pr_notice("reverting patch '%s' on unloading module '%s'\n", | |
1037 | patch->mod->name, obj->mod->name); | |
1038 | klp_disable_object(obj); | |
1039 | } | |
b700e7f0 | 1040 | |
7e545d6e | 1041 | klp_free_object_loaded(obj); |
b700e7f0 SJ |
1042 | break; |
1043 | } | |
1044 | } | |
1045 | ||
1046 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1047 | } |
1048 | ||
26029d88 | 1049 | static int __init klp_init(void) |
b700e7f0 SJ |
1050 | { |
1051 | int ret; | |
1052 | ||
b9dfe0be JK |
1053 | ret = klp_check_compiler_support(); |
1054 | if (ret) { | |
1055 | pr_info("Your compiler is too old; turning off.\n"); | |
1056 | return -EINVAL; | |
1057 | } | |
1058 | ||
b700e7f0 | 1059 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1060 | if (!klp_root_kobj) |
1061 | return -ENOMEM; | |
b700e7f0 SJ |
1062 | |
1063 | return 0; | |
b700e7f0 SJ |
1064 | } |
1065 | ||
1066 | module_init(klp_init); |