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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 | |
b56b36ee | 277 | module_disable_ro(pmod); |
425595a7 JY |
278 | /* For each klp relocation section */ |
279 | for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) { | |
280 | sec = pmod->klp_info->sechdrs + i; | |
281 | secname = pmod->klp_info->secstrings + sec->sh_name; | |
282 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
283 | continue; | |
284 | ||
285 | /* | |
286 | * Format: .klp.rela.sec_objname.section_name | |
287 | * See comment in klp_resolve_symbols() for an explanation | |
288 | * of the selected field width value. | |
289 | */ | |
290 | cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname); | |
291 | if (cnt != 1) { | |
292 | pr_err("section %s has an incorrectly formatted name", | |
293 | secname); | |
294 | ret = -EINVAL; | |
295 | break; | |
296 | } | |
297 | ||
298 | if (strcmp(objname, sec_objname)) | |
299 | continue; | |
b56b36ee | 300 | |
425595a7 | 301 | ret = klp_resolve_symbols(sec, pmod); |
064c89df | 302 | if (ret) |
425595a7 | 303 | break; |
064c89df | 304 | |
425595a7 JY |
305 | ret = apply_relocate_add(pmod->klp_info->sechdrs, |
306 | pmod->core_kallsyms.strtab, | |
307 | pmod->klp_info->symndx, i, pmod); | |
308 | if (ret) | |
309 | break; | |
b700e7f0 SJ |
310 | } |
311 | ||
b56b36ee JP |
312 | module_enable_ro(pmod); |
313 | return ret; | |
b700e7f0 SJ |
314 | } |
315 | ||
316 | static void notrace klp_ftrace_handler(unsigned long ip, | |
317 | unsigned long parent_ip, | |
3c33f5b9 | 318 | struct ftrace_ops *fops, |
b700e7f0 SJ |
319 | struct pt_regs *regs) |
320 | { | |
3c33f5b9 JP |
321 | struct klp_ops *ops; |
322 | struct klp_func *func; | |
323 | ||
324 | ops = container_of(fops, struct klp_ops, fops); | |
325 | ||
326 | rcu_read_lock(); | |
327 | func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, | |
328 | stack_node); | |
3c33f5b9 | 329 | if (WARN_ON_ONCE(!func)) |
c4ce0da8 | 330 | goto unlock; |
b700e7f0 | 331 | |
b5bfc517 | 332 | klp_arch_set_pc(regs, (unsigned long)func->new_func); |
c4ce0da8 PM |
333 | unlock: |
334 | rcu_read_unlock(); | |
b700e7f0 SJ |
335 | } |
336 | ||
28e7cbd3 ME |
337 | /* |
338 | * Convert a function address into the appropriate ftrace location. | |
339 | * | |
340 | * Usually this is just the address of the function, but on some architectures | |
341 | * it's more complicated so allow them to provide a custom behaviour. | |
342 | */ | |
343 | #ifndef klp_get_ftrace_location | |
344 | static unsigned long klp_get_ftrace_location(unsigned long faddr) | |
345 | { | |
346 | return faddr; | |
347 | } | |
348 | #endif | |
349 | ||
0937e3b0 | 350 | static void klp_disable_func(struct klp_func *func) |
b700e7f0 | 351 | { |
3c33f5b9 | 352 | struct klp_ops *ops; |
b700e7f0 | 353 | |
225f58fb MH |
354 | if (WARN_ON(func->state != KLP_ENABLED)) |
355 | return; | |
356 | if (WARN_ON(!func->old_addr)) | |
357 | return; | |
b700e7f0 | 358 | |
3c33f5b9 JP |
359 | ops = klp_find_ops(func->old_addr); |
360 | if (WARN_ON(!ops)) | |
0937e3b0 | 361 | return; |
b700e7f0 | 362 | |
3c33f5b9 | 363 | if (list_is_singular(&ops->func_stack)) { |
28e7cbd3 ME |
364 | unsigned long ftrace_loc; |
365 | ||
366 | ftrace_loc = klp_get_ftrace_location(func->old_addr); | |
367 | if (WARN_ON(!ftrace_loc)) | |
368 | return; | |
369 | ||
0937e3b0 | 370 | WARN_ON(unregister_ftrace_function(&ops->fops)); |
28e7cbd3 | 371 | WARN_ON(ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0)); |
3c33f5b9 JP |
372 | |
373 | list_del_rcu(&func->stack_node); | |
374 | list_del(&ops->node); | |
375 | kfree(ops); | |
376 | } else { | |
377 | list_del_rcu(&func->stack_node); | |
378 | } | |
b700e7f0 SJ |
379 | |
380 | func->state = KLP_DISABLED; | |
b700e7f0 SJ |
381 | } |
382 | ||
383 | static int klp_enable_func(struct klp_func *func) | |
384 | { | |
3c33f5b9 | 385 | struct klp_ops *ops; |
b700e7f0 SJ |
386 | int ret; |
387 | ||
388 | if (WARN_ON(!func->old_addr)) | |
389 | return -EINVAL; | |
390 | ||
391 | if (WARN_ON(func->state != KLP_DISABLED)) | |
392 | return -EINVAL; | |
393 | ||
3c33f5b9 JP |
394 | ops = klp_find_ops(func->old_addr); |
395 | if (!ops) { | |
28e7cbd3 ME |
396 | unsigned long ftrace_loc; |
397 | ||
398 | ftrace_loc = klp_get_ftrace_location(func->old_addr); | |
399 | if (!ftrace_loc) { | |
400 | pr_err("failed to find location for function '%s'\n", | |
401 | func->old_name); | |
402 | return -EINVAL; | |
403 | } | |
404 | ||
3c33f5b9 JP |
405 | ops = kzalloc(sizeof(*ops), GFP_KERNEL); |
406 | if (!ops) | |
407 | return -ENOMEM; | |
408 | ||
409 | ops->fops.func = klp_ftrace_handler; | |
410 | ops->fops.flags = FTRACE_OPS_FL_SAVE_REGS | | |
411 | FTRACE_OPS_FL_DYNAMIC | | |
412 | FTRACE_OPS_FL_IPMODIFY; | |
413 | ||
414 | list_add(&ops->node, &klp_ops); | |
415 | ||
416 | INIT_LIST_HEAD(&ops->func_stack); | |
417 | list_add_rcu(&func->stack_node, &ops->func_stack); | |
418 | ||
28e7cbd3 | 419 | ret = ftrace_set_filter_ip(&ops->fops, ftrace_loc, 0, 0); |
3c33f5b9 JP |
420 | if (ret) { |
421 | pr_err("failed to set ftrace filter for function '%s' (%d)\n", | |
422 | func->old_name, ret); | |
423 | goto err; | |
424 | } | |
425 | ||
426 | ret = register_ftrace_function(&ops->fops); | |
427 | if (ret) { | |
428 | pr_err("failed to register ftrace handler for function '%s' (%d)\n", | |
429 | func->old_name, ret); | |
28e7cbd3 | 430 | ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0); |
3c33f5b9 JP |
431 | goto err; |
432 | } | |
433 | ||
b700e7f0 | 434 | |
b700e7f0 | 435 | } else { |
3c33f5b9 | 436 | list_add_rcu(&func->stack_node, &ops->func_stack); |
b700e7f0 SJ |
437 | } |
438 | ||
3c33f5b9 JP |
439 | func->state = KLP_ENABLED; |
440 | ||
dbed7dda | 441 | return 0; |
3c33f5b9 JP |
442 | |
443 | err: | |
444 | list_del_rcu(&func->stack_node); | |
445 | list_del(&ops->node); | |
446 | kfree(ops); | |
b700e7f0 SJ |
447 | return ret; |
448 | } | |
449 | ||
0937e3b0 | 450 | static void klp_disable_object(struct klp_object *obj) |
b700e7f0 SJ |
451 | { |
452 | struct klp_func *func; | |
b700e7f0 | 453 | |
8cdd043a | 454 | klp_for_each_func(obj, func) |
0937e3b0 JP |
455 | if (func->state == KLP_ENABLED) |
456 | klp_disable_func(func); | |
b700e7f0 SJ |
457 | |
458 | obj->state = KLP_DISABLED; | |
b700e7f0 SJ |
459 | } |
460 | ||
461 | static int klp_enable_object(struct klp_object *obj) | |
462 | { | |
463 | struct klp_func *func; | |
464 | int ret; | |
465 | ||
466 | if (WARN_ON(obj->state != KLP_DISABLED)) | |
467 | return -EINVAL; | |
468 | ||
469 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
470 | return -EINVAL; | |
471 | ||
8cdd043a | 472 | klp_for_each_func(obj, func) { |
b700e7f0 | 473 | ret = klp_enable_func(func); |
0937e3b0 JP |
474 | if (ret) { |
475 | klp_disable_object(obj); | |
476 | return ret; | |
477 | } | |
b700e7f0 SJ |
478 | } |
479 | obj->state = KLP_ENABLED; | |
480 | ||
481 | return 0; | |
b700e7f0 SJ |
482 | } |
483 | ||
484 | static int __klp_disable_patch(struct klp_patch *patch) | |
485 | { | |
486 | struct klp_object *obj; | |
b700e7f0 | 487 | |
83a90bb1 JP |
488 | /* enforce stacking: only the last enabled patch can be disabled */ |
489 | if (!list_is_last(&patch->list, &klp_patches) && | |
490 | list_next_entry(patch, list)->state == KLP_ENABLED) | |
491 | return -EBUSY; | |
492 | ||
b700e7f0 SJ |
493 | pr_notice("disabling patch '%s'\n", patch->mod->name); |
494 | ||
8cdd043a | 495 | klp_for_each_object(patch, obj) { |
0937e3b0 JP |
496 | if (obj->state == KLP_ENABLED) |
497 | klp_disable_object(obj); | |
b700e7f0 SJ |
498 | } |
499 | ||
500 | patch->state = KLP_DISABLED; | |
501 | ||
502 | return 0; | |
503 | } | |
504 | ||
505 | /** | |
506 | * klp_disable_patch() - disables a registered patch | |
507 | * @patch: The registered, enabled patch to be disabled | |
508 | * | |
509 | * Unregisters the patched functions from ftrace. | |
510 | * | |
511 | * Return: 0 on success, otherwise error | |
512 | */ | |
513 | int klp_disable_patch(struct klp_patch *patch) | |
514 | { | |
515 | int ret; | |
516 | ||
517 | mutex_lock(&klp_mutex); | |
518 | ||
519 | if (!klp_is_patch_registered(patch)) { | |
520 | ret = -EINVAL; | |
521 | goto err; | |
522 | } | |
523 | ||
524 | if (patch->state == KLP_DISABLED) { | |
525 | ret = -EINVAL; | |
526 | goto err; | |
527 | } | |
528 | ||
529 | ret = __klp_disable_patch(patch); | |
530 | ||
531 | err: | |
532 | mutex_unlock(&klp_mutex); | |
533 | return ret; | |
534 | } | |
535 | EXPORT_SYMBOL_GPL(klp_disable_patch); | |
536 | ||
537 | static int __klp_enable_patch(struct klp_patch *patch) | |
538 | { | |
539 | struct klp_object *obj; | |
540 | int ret; | |
541 | ||
542 | if (WARN_ON(patch->state != KLP_DISABLED)) | |
543 | return -EINVAL; | |
544 | ||
83a90bb1 JP |
545 | /* enforce stacking: only the first disabled patch can be enabled */ |
546 | if (patch->list.prev != &klp_patches && | |
547 | list_prev_entry(patch, list)->state == KLP_DISABLED) | |
548 | return -EBUSY; | |
549 | ||
b700e7f0 SJ |
550 | pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n"); |
551 | add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK); | |
552 | ||
553 | pr_notice("enabling patch '%s'\n", patch->mod->name); | |
554 | ||
8cdd043a | 555 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
556 | if (!klp_is_object_loaded(obj)) |
557 | continue; | |
558 | ||
559 | ret = klp_enable_object(obj); | |
560 | if (ret) | |
561 | goto unregister; | |
562 | } | |
563 | ||
564 | patch->state = KLP_ENABLED; | |
565 | ||
566 | return 0; | |
567 | ||
568 | unregister: | |
569 | WARN_ON(__klp_disable_patch(patch)); | |
570 | return ret; | |
571 | } | |
572 | ||
573 | /** | |
574 | * klp_enable_patch() - enables a registered patch | |
575 | * @patch: The registered, disabled patch to be enabled | |
576 | * | |
577 | * Performs the needed symbol lookups and code relocations, | |
578 | * then registers the patched functions with ftrace. | |
579 | * | |
580 | * Return: 0 on success, otherwise error | |
581 | */ | |
582 | int klp_enable_patch(struct klp_patch *patch) | |
583 | { | |
584 | int ret; | |
585 | ||
586 | mutex_lock(&klp_mutex); | |
587 | ||
588 | if (!klp_is_patch_registered(patch)) { | |
589 | ret = -EINVAL; | |
590 | goto err; | |
591 | } | |
592 | ||
593 | ret = __klp_enable_patch(patch); | |
594 | ||
595 | err: | |
596 | mutex_unlock(&klp_mutex); | |
597 | return ret; | |
598 | } | |
599 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
600 | ||
601 | /* | |
602 | * Sysfs Interface | |
603 | * | |
604 | * /sys/kernel/livepatch | |
605 | * /sys/kernel/livepatch/<patch> | |
606 | * /sys/kernel/livepatch/<patch>/enabled | |
607 | * /sys/kernel/livepatch/<patch>/<object> | |
444f9e99 | 608 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 SJ |
609 | */ |
610 | ||
611 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
612 | const char *buf, size_t count) | |
613 | { | |
614 | struct klp_patch *patch; | |
615 | int ret; | |
616 | unsigned long val; | |
617 | ||
618 | ret = kstrtoul(buf, 10, &val); | |
619 | if (ret) | |
620 | return -EINVAL; | |
621 | ||
622 | if (val != KLP_DISABLED && val != KLP_ENABLED) | |
623 | return -EINVAL; | |
624 | ||
625 | patch = container_of(kobj, struct klp_patch, kobj); | |
626 | ||
627 | mutex_lock(&klp_mutex); | |
628 | ||
629 | if (val == patch->state) { | |
630 | /* already in requested state */ | |
631 | ret = -EINVAL; | |
632 | goto err; | |
633 | } | |
634 | ||
635 | if (val == KLP_ENABLED) { | |
636 | ret = __klp_enable_patch(patch); | |
637 | if (ret) | |
638 | goto err; | |
639 | } else { | |
640 | ret = __klp_disable_patch(patch); | |
641 | if (ret) | |
642 | goto err; | |
643 | } | |
644 | ||
645 | mutex_unlock(&klp_mutex); | |
646 | ||
647 | return count; | |
648 | ||
649 | err: | |
650 | mutex_unlock(&klp_mutex); | |
651 | return ret; | |
652 | } | |
653 | ||
654 | static ssize_t enabled_show(struct kobject *kobj, | |
655 | struct kobj_attribute *attr, char *buf) | |
656 | { | |
657 | struct klp_patch *patch; | |
658 | ||
659 | patch = container_of(kobj, struct klp_patch, kobj); | |
660 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->state); | |
661 | } | |
662 | ||
663 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); | |
664 | static struct attribute *klp_patch_attrs[] = { | |
665 | &enabled_kobj_attr.attr, | |
666 | NULL | |
667 | }; | |
668 | ||
669 | static void klp_kobj_release_patch(struct kobject *kobj) | |
670 | { | |
671 | /* | |
672 | * Once we have a consistency model we'll need to module_put() the | |
673 | * patch module here. See klp_register_patch() for more details. | |
674 | */ | |
675 | } | |
676 | ||
677 | static struct kobj_type klp_ktype_patch = { | |
678 | .release = klp_kobj_release_patch, | |
679 | .sysfs_ops = &kobj_sysfs_ops, | |
680 | .default_attrs = klp_patch_attrs, | |
681 | }; | |
682 | ||
cad706df MB |
683 | static void klp_kobj_release_object(struct kobject *kobj) |
684 | { | |
685 | } | |
686 | ||
687 | static struct kobj_type klp_ktype_object = { | |
688 | .release = klp_kobj_release_object, | |
689 | .sysfs_ops = &kobj_sysfs_ops, | |
690 | }; | |
691 | ||
b700e7f0 SJ |
692 | static void klp_kobj_release_func(struct kobject *kobj) |
693 | { | |
b700e7f0 SJ |
694 | } |
695 | ||
696 | static struct kobj_type klp_ktype_func = { | |
697 | .release = klp_kobj_release_func, | |
698 | .sysfs_ops = &kobj_sysfs_ops, | |
699 | }; | |
700 | ||
701 | /* | |
702 | * Free all functions' kobjects in the array up to some limit. When limit is | |
703 | * NULL, all kobjects are freed. | |
704 | */ | |
705 | static void klp_free_funcs_limited(struct klp_object *obj, | |
706 | struct klp_func *limit) | |
707 | { | |
708 | struct klp_func *func; | |
709 | ||
710 | for (func = obj->funcs; func->old_name && func != limit; func++) | |
711 | kobject_put(&func->kobj); | |
712 | } | |
713 | ||
714 | /* Clean up when a patched object is unloaded */ | |
715 | static void klp_free_object_loaded(struct klp_object *obj) | |
716 | { | |
717 | struct klp_func *func; | |
718 | ||
719 | obj->mod = NULL; | |
720 | ||
8cdd043a | 721 | klp_for_each_func(obj, func) |
b700e7f0 SJ |
722 | func->old_addr = 0; |
723 | } | |
724 | ||
725 | /* | |
726 | * Free all objects' kobjects in the array up to some limit. When limit is | |
727 | * NULL, all kobjects are freed. | |
728 | */ | |
729 | static void klp_free_objects_limited(struct klp_patch *patch, | |
730 | struct klp_object *limit) | |
731 | { | |
732 | struct klp_object *obj; | |
733 | ||
734 | for (obj = patch->objs; obj->funcs && obj != limit; obj++) { | |
735 | klp_free_funcs_limited(obj, NULL); | |
cad706df | 736 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
737 | } |
738 | } | |
739 | ||
740 | static void klp_free_patch(struct klp_patch *patch) | |
741 | { | |
742 | klp_free_objects_limited(patch, NULL); | |
743 | if (!list_empty(&patch->list)) | |
744 | list_del(&patch->list); | |
745 | kobject_put(&patch->kobj); | |
746 | } | |
747 | ||
748 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
749 | { | |
3c33f5b9 | 750 | INIT_LIST_HEAD(&func->stack_node); |
b700e7f0 SJ |
751 | func->state = KLP_DISABLED; |
752 | ||
444f9e99 CA |
753 | /* The format for the sysfs directory is <function,sympos> where sympos |
754 | * is the nth occurrence of this symbol in kallsyms for the patched | |
755 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
756 | * since a unique symbol will be the first occurrence. | |
757 | */ | |
3c33f5b9 | 758 | return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
444f9e99 CA |
759 | &obj->kobj, "%s,%lu", func->old_name, |
760 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
761 | } |
762 | ||
763 | /* parts of the initialization that is done only when the object is loaded */ | |
764 | static int klp_init_object_loaded(struct klp_patch *patch, | |
765 | struct klp_object *obj) | |
766 | { | |
767 | struct klp_func *func; | |
768 | int ret; | |
769 | ||
425595a7 JY |
770 | ret = klp_write_object_relocations(patch->mod, obj); |
771 | if (ret) | |
772 | return ret; | |
b700e7f0 | 773 | |
8cdd043a | 774 | klp_for_each_func(obj, func) { |
b2b018ef CA |
775 | ret = klp_find_object_symbol(obj->name, func->old_name, |
776 | func->old_sympos, | |
777 | &func->old_addr); | |
b700e7f0 SJ |
778 | if (ret) |
779 | return ret; | |
780 | } | |
781 | ||
782 | return 0; | |
783 | } | |
784 | ||
785 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
786 | { | |
787 | struct klp_func *func; | |
788 | int ret; | |
789 | const char *name; | |
790 | ||
791 | if (!obj->funcs) | |
792 | return -EINVAL; | |
793 | ||
794 | obj->state = KLP_DISABLED; | |
8cb2c2dc | 795 | obj->mod = NULL; |
b700e7f0 SJ |
796 | |
797 | klp_find_object_module(obj); | |
798 | ||
799 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
cad706df MB |
800 | ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object, |
801 | &patch->kobj, "%s", name); | |
802 | if (ret) | |
803 | return ret; | |
b700e7f0 | 804 | |
8cdd043a | 805 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
806 | ret = klp_init_func(obj, func); |
807 | if (ret) | |
808 | goto free; | |
809 | } | |
810 | ||
811 | if (klp_is_object_loaded(obj)) { | |
812 | ret = klp_init_object_loaded(patch, obj); | |
813 | if (ret) | |
814 | goto free; | |
815 | } | |
816 | ||
817 | return 0; | |
818 | ||
819 | free: | |
820 | klp_free_funcs_limited(obj, func); | |
cad706df | 821 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
822 | return ret; |
823 | } | |
824 | ||
825 | static int klp_init_patch(struct klp_patch *patch) | |
826 | { | |
827 | struct klp_object *obj; | |
828 | int ret; | |
829 | ||
830 | if (!patch->objs) | |
831 | return -EINVAL; | |
832 | ||
833 | mutex_lock(&klp_mutex); | |
834 | ||
835 | patch->state = KLP_DISABLED; | |
836 | ||
837 | ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, | |
e0b561ee | 838 | klp_root_kobj, "%s", patch->mod->name); |
b700e7f0 SJ |
839 | if (ret) |
840 | goto unlock; | |
841 | ||
8cdd043a | 842 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
843 | ret = klp_init_object(patch, obj); |
844 | if (ret) | |
845 | goto free; | |
846 | } | |
847 | ||
99590ba5 | 848 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
849 | |
850 | mutex_unlock(&klp_mutex); | |
851 | ||
852 | return 0; | |
853 | ||
854 | free: | |
855 | klp_free_objects_limited(patch, obj); | |
856 | kobject_put(&patch->kobj); | |
857 | unlock: | |
858 | mutex_unlock(&klp_mutex); | |
859 | return ret; | |
860 | } | |
861 | ||
862 | /** | |
863 | * klp_unregister_patch() - unregisters a patch | |
864 | * @patch: Disabled patch to be unregistered | |
865 | * | |
866 | * Frees the data structures and removes the sysfs interface. | |
867 | * | |
868 | * Return: 0 on success, otherwise error | |
869 | */ | |
870 | int klp_unregister_patch(struct klp_patch *patch) | |
871 | { | |
872 | int ret = 0; | |
873 | ||
874 | mutex_lock(&klp_mutex); | |
875 | ||
876 | if (!klp_is_patch_registered(patch)) { | |
877 | ret = -EINVAL; | |
878 | goto out; | |
879 | } | |
880 | ||
881 | if (patch->state == KLP_ENABLED) { | |
882 | ret = -EBUSY; | |
883 | goto out; | |
884 | } | |
885 | ||
886 | klp_free_patch(patch); | |
887 | ||
888 | out: | |
889 | mutex_unlock(&klp_mutex); | |
890 | return ret; | |
891 | } | |
892 | EXPORT_SYMBOL_GPL(klp_unregister_patch); | |
893 | ||
894 | /** | |
895 | * klp_register_patch() - registers a patch | |
896 | * @patch: Patch to be registered | |
897 | * | |
898 | * Initializes the data structure associated with the patch and | |
899 | * creates the sysfs interface. | |
900 | * | |
901 | * Return: 0 on success, otherwise error | |
902 | */ | |
903 | int klp_register_patch(struct klp_patch *patch) | |
904 | { | |
905 | int ret; | |
906 | ||
61bf12d3 JK |
907 | if (!patch || !patch->mod) |
908 | return -EINVAL; | |
909 | ||
425595a7 JY |
910 | if (!is_livepatch_module(patch->mod)) { |
911 | pr_err("module %s is not marked as a livepatch module", | |
912 | patch->mod->name); | |
913 | return -EINVAL; | |
914 | } | |
915 | ||
b700e7f0 SJ |
916 | if (!klp_initialized()) |
917 | return -ENODEV; | |
918 | ||
b700e7f0 SJ |
919 | /* |
920 | * A reference is taken on the patch module to prevent it from being | |
921 | * unloaded. Right now, we don't allow patch modules to unload since | |
922 | * there is currently no method to determine if a thread is still | |
923 | * running in the patched code contained in the patch module once | |
924 | * the ftrace registration is successful. | |
925 | */ | |
926 | if (!try_module_get(patch->mod)) | |
927 | return -ENODEV; | |
928 | ||
929 | ret = klp_init_patch(patch); | |
930 | if (ret) | |
931 | module_put(patch->mod); | |
932 | ||
933 | return ret; | |
934 | } | |
935 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
936 | ||
7e545d6e | 937 | int klp_module_coming(struct module *mod) |
b700e7f0 | 938 | { |
b700e7f0 | 939 | int ret; |
7e545d6e JY |
940 | struct klp_patch *patch; |
941 | struct klp_object *obj; | |
b700e7f0 | 942 | |
7e545d6e JY |
943 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
944 | return -EINVAL; | |
b700e7f0 | 945 | |
7e545d6e JY |
946 | mutex_lock(&klp_mutex); |
947 | /* | |
948 | * Each module has to know that klp_module_coming() | |
949 | * has been called. We never know what module will | |
950 | * get patched by a new patch. | |
951 | */ | |
952 | mod->klp_alive = true; | |
b700e7f0 | 953 | |
7e545d6e JY |
954 | list_for_each_entry(patch, &klp_patches, list) { |
955 | klp_for_each_object(patch, obj) { | |
956 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
957 | continue; | |
b700e7f0 | 958 | |
7e545d6e | 959 | obj->mod = mod; |
b700e7f0 | 960 | |
7e545d6e JY |
961 | ret = klp_init_object_loaded(patch, obj); |
962 | if (ret) { | |
963 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
964 | patch->mod->name, obj->mod->name, ret); | |
965 | goto err; | |
966 | } | |
b700e7f0 | 967 | |
7e545d6e JY |
968 | if (patch->state == KLP_DISABLED) |
969 | break; | |
970 | ||
971 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
972 | patch->mod->name, obj->mod->name); | |
973 | ||
974 | ret = klp_enable_object(obj); | |
975 | if (ret) { | |
976 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
977 | patch->mod->name, obj->mod->name, ret); | |
978 | goto err; | |
979 | } | |
980 | ||
981 | break; | |
982 | } | |
983 | } | |
b700e7f0 | 984 | |
7e545d6e | 985 | mutex_unlock(&klp_mutex); |
b700e7f0 | 986 | |
7e545d6e | 987 | return 0; |
b700e7f0 | 988 | |
7e545d6e JY |
989 | err: |
990 | /* | |
991 | * If a patch is unsuccessfully applied, return | |
992 | * error to the module loader. | |
993 | */ | |
994 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
995 | patch->mod->name, obj->mod->name, obj->mod->name); | |
996 | mod->klp_alive = false; | |
b700e7f0 | 997 | klp_free_object_loaded(obj); |
7e545d6e JY |
998 | mutex_unlock(&klp_mutex); |
999 | ||
1000 | return ret; | |
b700e7f0 SJ |
1001 | } |
1002 | ||
7e545d6e | 1003 | void klp_module_going(struct module *mod) |
b700e7f0 | 1004 | { |
b700e7f0 SJ |
1005 | struct klp_patch *patch; |
1006 | struct klp_object *obj; | |
1007 | ||
7e545d6e JY |
1008 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1009 | mod->state != MODULE_STATE_COMING)) | |
1010 | return; | |
b700e7f0 SJ |
1011 | |
1012 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1013 | /* |
7e545d6e JY |
1014 | * Each module has to know that klp_module_going() |
1015 | * has been called. We never know what module will | |
1016 | * get patched by a new patch. | |
8cb2c2dc | 1017 | */ |
7e545d6e | 1018 | mod->klp_alive = false; |
8cb2c2dc | 1019 | |
b700e7f0 | 1020 | list_for_each_entry(patch, &klp_patches, list) { |
8cdd043a | 1021 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
1022 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) |
1023 | continue; | |
1024 | ||
7e545d6e JY |
1025 | if (patch->state != KLP_DISABLED) { |
1026 | pr_notice("reverting patch '%s' on unloading module '%s'\n", | |
1027 | patch->mod->name, obj->mod->name); | |
1028 | klp_disable_object(obj); | |
1029 | } | |
b700e7f0 | 1030 | |
7e545d6e | 1031 | klp_free_object_loaded(obj); |
b700e7f0 SJ |
1032 | break; |
1033 | } | |
1034 | } | |
1035 | ||
1036 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1037 | } |
1038 | ||
26029d88 | 1039 | static int __init klp_init(void) |
b700e7f0 SJ |
1040 | { |
1041 | int ret; | |
1042 | ||
b9dfe0be JK |
1043 | ret = klp_check_compiler_support(); |
1044 | if (ret) { | |
1045 | pr_info("Your compiler is too old; turning off.\n"); | |
1046 | return -EINVAL; | |
1047 | } | |
1048 | ||
b700e7f0 | 1049 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1050 | if (!klp_root_kobj) |
1051 | return -ENOMEM; | |
b700e7f0 SJ |
1052 | |
1053 | return 0; | |
b700e7f0 SJ |
1054 | } |
1055 | ||
1056 | module_init(klp_init); |