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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> | |
b700e7f0 SJ |
27 | #include <linux/list.h> |
28 | #include <linux/kallsyms.h> | |
29 | #include <linux/livepatch.h> | |
425595a7 JY |
30 | #include <linux/elf.h> |
31 | #include <linux/moduleloader.h> | |
3ec24776 | 32 | #include <linux/completion.h> |
b56b36ee | 33 | #include <asm/cacheflush.h> |
10517429 | 34 | #include "core.h" |
c349cdca | 35 | #include "patch.h" |
d83a7cb3 | 36 | #include "transition.h" |
b700e7f0 | 37 | |
3c33f5b9 | 38 | /* |
d83a7cb3 JP |
39 | * klp_mutex is a coarse lock which serializes access to klp data. All |
40 | * accesses to klp-related variables and structures must have mutex protection, | |
41 | * except within the following functions which carefully avoid the need for it: | |
42 | * | |
43 | * - klp_ftrace_handler() | |
44 | * - klp_update_patch_state() | |
3c33f5b9 | 45 | */ |
d83a7cb3 | 46 | DEFINE_MUTEX(klp_mutex); |
3c33f5b9 | 47 | |
b700e7f0 SJ |
48 | static LIST_HEAD(klp_patches); |
49 | ||
50 | static struct kobject *klp_root_kobj; | |
51 | ||
52 | static bool klp_is_module(struct klp_object *obj) | |
53 | { | |
54 | return obj->name; | |
55 | } | |
56 | ||
57 | static bool klp_is_object_loaded(struct klp_object *obj) | |
58 | { | |
59 | return !obj->name || obj->mod; | |
60 | } | |
61 | ||
62 | /* sets obj->mod if object is not vmlinux and module is found */ | |
63 | static void klp_find_object_module(struct klp_object *obj) | |
64 | { | |
8cb2c2dc PM |
65 | struct module *mod; |
66 | ||
b700e7f0 SJ |
67 | if (!klp_is_module(obj)) |
68 | return; | |
69 | ||
70 | mutex_lock(&module_mutex); | |
71 | /* | |
8cb2c2dc PM |
72 | * We do not want to block removal of patched modules and therefore |
73 | * we do not take a reference here. The patches are removed by | |
7e545d6e | 74 | * klp_module_going() instead. |
8cb2c2dc PM |
75 | */ |
76 | mod = find_module(obj->name); | |
77 | /* | |
7e545d6e JY |
78 | * Do not mess work of klp_module_coming() and klp_module_going(). |
79 | * Note that the patch might still be needed before klp_module_going() | |
8cb2c2dc PM |
80 | * is called. Module functions can be called even in the GOING state |
81 | * until mod->exit() finishes. This is especially important for | |
82 | * patches that modify semantic of the functions. | |
b700e7f0 | 83 | */ |
8cb2c2dc PM |
84 | if (mod && mod->klp_alive) |
85 | obj->mod = mod; | |
86 | ||
b700e7f0 SJ |
87 | mutex_unlock(&module_mutex); |
88 | } | |
89 | ||
b700e7f0 SJ |
90 | static bool klp_is_patch_registered(struct klp_patch *patch) |
91 | { | |
92 | struct klp_patch *mypatch; | |
93 | ||
94 | list_for_each_entry(mypatch, &klp_patches, list) | |
95 | if (mypatch == patch) | |
96 | return true; | |
97 | ||
98 | return false; | |
99 | } | |
100 | ||
101 | static bool klp_initialized(void) | |
102 | { | |
e76ff06a | 103 | return !!klp_root_kobj; |
b700e7f0 SJ |
104 | } |
105 | ||
106 | struct klp_find_arg { | |
107 | const char *objname; | |
108 | const char *name; | |
109 | unsigned long addr; | |
b700e7f0 | 110 | unsigned long count; |
b2b018ef | 111 | unsigned long pos; |
b700e7f0 SJ |
112 | }; |
113 | ||
114 | static int klp_find_callback(void *data, const char *name, | |
115 | struct module *mod, unsigned long addr) | |
116 | { | |
117 | struct klp_find_arg *args = data; | |
118 | ||
119 | if ((mod && !args->objname) || (!mod && args->objname)) | |
120 | return 0; | |
121 | ||
122 | if (strcmp(args->name, name)) | |
123 | return 0; | |
124 | ||
125 | if (args->objname && strcmp(args->objname, mod->name)) | |
126 | return 0; | |
127 | ||
b700e7f0 SJ |
128 | args->addr = addr; |
129 | args->count++; | |
130 | ||
b2b018ef CA |
131 | /* |
132 | * Finish the search when the symbol is found for the desired position | |
133 | * or the position is not defined for a non-unique symbol. | |
134 | */ | |
135 | if ((args->pos && (args->count == args->pos)) || | |
136 | (!args->pos && (args->count > 1))) | |
137 | return 1; | |
138 | ||
b700e7f0 SJ |
139 | return 0; |
140 | } | |
141 | ||
142 | static int klp_find_object_symbol(const char *objname, const char *name, | |
b2b018ef | 143 | unsigned long sympos, unsigned long *addr) |
b700e7f0 SJ |
144 | { |
145 | struct klp_find_arg args = { | |
146 | .objname = objname, | |
147 | .name = name, | |
148 | .addr = 0, | |
b2b018ef CA |
149 | .count = 0, |
150 | .pos = sympos, | |
b700e7f0 SJ |
151 | }; |
152 | ||
9a1bd63c | 153 | mutex_lock(&module_mutex); |
72f04b50 ZC |
154 | if (objname) |
155 | module_kallsyms_on_each_symbol(klp_find_callback, &args); | |
156 | else | |
157 | kallsyms_on_each_symbol(klp_find_callback, &args); | |
9a1bd63c | 158 | mutex_unlock(&module_mutex); |
b700e7f0 | 159 | |
b2b018ef CA |
160 | /* |
161 | * Ensure an address was found. If sympos is 0, ensure symbol is unique; | |
162 | * otherwise ensure the symbol position count matches sympos. | |
163 | */ | |
164 | if (args.addr == 0) | |
b700e7f0 | 165 | pr_err("symbol '%s' not found in symbol table\n", name); |
b2b018ef | 166 | else if (args.count > 1 && sympos == 0) { |
f995b5f7 PM |
167 | pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n", |
168 | name, objname); | |
b2b018ef CA |
169 | } else if (sympos != args.count && sympos > 0) { |
170 | pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n", | |
171 | sympos, name, objname ? objname : "vmlinux"); | |
172 | } else { | |
b700e7f0 SJ |
173 | *addr = args.addr; |
174 | return 0; | |
175 | } | |
176 | ||
177 | *addr = 0; | |
178 | return -EINVAL; | |
179 | } | |
180 | ||
425595a7 | 181 | static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod) |
b700e7f0 | 182 | { |
425595a7 JY |
183 | int i, cnt, vmlinux, ret; |
184 | char objname[MODULE_NAME_LEN]; | |
185 | char symname[KSYM_NAME_LEN]; | |
186 | char *strtab = pmod->core_kallsyms.strtab; | |
187 | Elf_Rela *relas; | |
188 | Elf_Sym *sym; | |
189 | unsigned long sympos, addr; | |
b700e7f0 | 190 | |
b2b018ef | 191 | /* |
425595a7 JY |
192 | * Since the field widths for objname and symname in the sscanf() |
193 | * call are hard-coded and correspond to MODULE_NAME_LEN and | |
194 | * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN | |
195 | * and KSYM_NAME_LEN have the values we expect them to have. | |
196 | * | |
197 | * Because the value of MODULE_NAME_LEN can differ among architectures, | |
198 | * we use the smallest/strictest upper bound possible (56, based on | |
199 | * the current definition of MODULE_NAME_LEN) to prevent overflows. | |
b2b018ef | 200 | */ |
425595a7 JY |
201 | BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); |
202 | ||
203 | relas = (Elf_Rela *) relasec->sh_addr; | |
204 | /* For each rela in this klp relocation section */ | |
205 | for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { | |
206 | sym = pmod->core_kallsyms.symtab + ELF_R_SYM(relas[i].r_info); | |
207 | if (sym->st_shndx != SHN_LIVEPATCH) { | |
77f8f39a | 208 | pr_err("symbol %s is not marked as a livepatch symbol\n", |
425595a7 JY |
209 | strtab + sym->st_name); |
210 | return -EINVAL; | |
211 | } | |
212 | ||
213 | /* Format: .klp.sym.objname.symname,sympos */ | |
214 | cnt = sscanf(strtab + sym->st_name, | |
215 | ".klp.sym.%55[^.].%127[^,],%lu", | |
216 | objname, symname, &sympos); | |
217 | if (cnt != 3) { | |
77f8f39a | 218 | pr_err("symbol %s has an incorrectly formatted name\n", |
425595a7 JY |
219 | strtab + sym->st_name); |
220 | return -EINVAL; | |
221 | } | |
222 | ||
223 | /* klp_find_object_symbol() treats a NULL objname as vmlinux */ | |
224 | vmlinux = !strcmp(objname, "vmlinux"); | |
225 | ret = klp_find_object_symbol(vmlinux ? NULL : objname, | |
226 | symname, sympos, &addr); | |
227 | if (ret) | |
228 | return ret; | |
229 | ||
230 | sym->st_value = addr; | |
231 | } | |
232 | ||
233 | return 0; | |
b700e7f0 SJ |
234 | } |
235 | ||
236 | static int klp_write_object_relocations(struct module *pmod, | |
237 | struct klp_object *obj) | |
238 | { | |
425595a7 JY |
239 | int i, cnt, ret = 0; |
240 | const char *objname, *secname; | |
241 | char sec_objname[MODULE_NAME_LEN]; | |
242 | Elf_Shdr *sec; | |
b700e7f0 SJ |
243 | |
244 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
245 | return -EINVAL; | |
246 | ||
425595a7 | 247 | objname = klp_is_module(obj) ? obj->name : "vmlinux"; |
b700e7f0 | 248 | |
425595a7 JY |
249 | /* For each klp relocation section */ |
250 | for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) { | |
251 | sec = pmod->klp_info->sechdrs + i; | |
252 | secname = pmod->klp_info->secstrings + sec->sh_name; | |
253 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
254 | continue; | |
b56b36ee | 255 | |
425595a7 JY |
256 | /* |
257 | * Format: .klp.rela.sec_objname.section_name | |
258 | * See comment in klp_resolve_symbols() for an explanation | |
259 | * of the selected field width value. | |
260 | */ | |
261 | cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname); | |
262 | if (cnt != 1) { | |
77f8f39a | 263 | pr_err("section %s has an incorrectly formatted name\n", |
425595a7 JY |
264 | secname); |
265 | ret = -EINVAL; | |
266 | break; | |
267 | } | |
b56b36ee | 268 | |
425595a7 JY |
269 | if (strcmp(objname, sec_objname)) |
270 | continue; | |
b56b36ee | 271 | |
425595a7 | 272 | ret = klp_resolve_symbols(sec, pmod); |
064c89df | 273 | if (ret) |
425595a7 | 274 | break; |
064c89df | 275 | |
425595a7 JY |
276 | ret = apply_relocate_add(pmod->klp_info->sechdrs, |
277 | pmod->core_kallsyms.strtab, | |
278 | pmod->klp_info->symndx, i, pmod); | |
279 | if (ret) | |
280 | break; | |
b700e7f0 SJ |
281 | } |
282 | ||
b56b36ee | 283 | return ret; |
b700e7f0 SJ |
284 | } |
285 | ||
b700e7f0 SJ |
286 | static int __klp_disable_patch(struct klp_patch *patch) |
287 | { | |
d83a7cb3 JP |
288 | if (klp_transition_patch) |
289 | return -EBUSY; | |
b700e7f0 | 290 | |
83a90bb1 JP |
291 | /* enforce stacking: only the last enabled patch can be disabled */ |
292 | if (!list_is_last(&patch->list, &klp_patches) && | |
0dade9f3 | 293 | list_next_entry(patch, list)->enabled) |
83a90bb1 JP |
294 | return -EBUSY; |
295 | ||
d83a7cb3 | 296 | klp_init_transition(patch, KLP_UNPATCHED); |
b700e7f0 | 297 | |
d83a7cb3 JP |
298 | /* |
299 | * Enforce the order of the func->transition writes in | |
300 | * klp_init_transition() and the TIF_PATCH_PENDING writes in | |
301 | * klp_start_transition(). In the rare case where klp_ftrace_handler() | |
302 | * is called shortly after klp_update_patch_state() switches the task, | |
303 | * this ensures the handler sees that func->transition is set. | |
304 | */ | |
305 | smp_wmb(); | |
b700e7f0 | 306 | |
d83a7cb3 JP |
307 | klp_start_transition(); |
308 | klp_try_complete_transition(); | |
0dade9f3 | 309 | patch->enabled = false; |
b700e7f0 SJ |
310 | |
311 | return 0; | |
312 | } | |
313 | ||
314 | /** | |
315 | * klp_disable_patch() - disables a registered patch | |
316 | * @patch: The registered, enabled patch to be disabled | |
317 | * | |
318 | * Unregisters the patched functions from ftrace. | |
319 | * | |
320 | * Return: 0 on success, otherwise error | |
321 | */ | |
322 | int klp_disable_patch(struct klp_patch *patch) | |
323 | { | |
324 | int ret; | |
325 | ||
326 | mutex_lock(&klp_mutex); | |
327 | ||
328 | if (!klp_is_patch_registered(patch)) { | |
329 | ret = -EINVAL; | |
330 | goto err; | |
331 | } | |
332 | ||
0dade9f3 | 333 | if (!patch->enabled) { |
b700e7f0 SJ |
334 | ret = -EINVAL; |
335 | goto err; | |
336 | } | |
337 | ||
338 | ret = __klp_disable_patch(patch); | |
339 | ||
340 | err: | |
341 | mutex_unlock(&klp_mutex); | |
342 | return ret; | |
343 | } | |
344 | EXPORT_SYMBOL_GPL(klp_disable_patch); | |
345 | ||
346 | static int __klp_enable_patch(struct klp_patch *patch) | |
347 | { | |
348 | struct klp_object *obj; | |
349 | int ret; | |
350 | ||
d83a7cb3 JP |
351 | if (klp_transition_patch) |
352 | return -EBUSY; | |
353 | ||
0dade9f3 | 354 | if (WARN_ON(patch->enabled)) |
b700e7f0 SJ |
355 | return -EINVAL; |
356 | ||
83a90bb1 JP |
357 | /* enforce stacking: only the first disabled patch can be enabled */ |
358 | if (patch->list.prev != &klp_patches && | |
0dade9f3 | 359 | !list_prev_entry(patch, list)->enabled) |
83a90bb1 JP |
360 | return -EBUSY; |
361 | ||
3ec24776 JP |
362 | /* |
363 | * A reference is taken on the patch module to prevent it from being | |
364 | * unloaded. | |
365 | * | |
366 | * Note: For immediate (no consistency model) patches we don't allow | |
367 | * patch modules to unload since there is no safe/sane method to | |
368 | * determine if a thread is still running in the patched code contained | |
369 | * in the patch module once the ftrace registration is successful. | |
370 | */ | |
371 | if (!try_module_get(patch->mod)) | |
372 | return -ENODEV; | |
373 | ||
b700e7f0 SJ |
374 | pr_notice("enabling patch '%s'\n", patch->mod->name); |
375 | ||
d83a7cb3 JP |
376 | klp_init_transition(patch, KLP_PATCHED); |
377 | ||
378 | /* | |
379 | * Enforce the order of the func->transition writes in | |
380 | * klp_init_transition() and the ops->func_stack writes in | |
381 | * klp_patch_object(), so that klp_ftrace_handler() will see the | |
382 | * func->transition updates before the handler is registered and the | |
383 | * new funcs become visible to the handler. | |
384 | */ | |
385 | smp_wmb(); | |
386 | ||
8cdd043a | 387 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
388 | if (!klp_is_object_loaded(obj)) |
389 | continue; | |
390 | ||
0dade9f3 | 391 | ret = klp_patch_object(obj); |
d83a7cb3 JP |
392 | if (ret) { |
393 | pr_warn("failed to enable patch '%s'\n", | |
394 | patch->mod->name); | |
395 | ||
396 | klp_cancel_transition(); | |
397 | return ret; | |
398 | } | |
b700e7f0 SJ |
399 | } |
400 | ||
d83a7cb3 JP |
401 | klp_start_transition(); |
402 | klp_try_complete_transition(); | |
0dade9f3 | 403 | patch->enabled = true; |
b700e7f0 SJ |
404 | |
405 | return 0; | |
b700e7f0 SJ |
406 | } |
407 | ||
408 | /** | |
409 | * klp_enable_patch() - enables a registered patch | |
410 | * @patch: The registered, disabled patch to be enabled | |
411 | * | |
412 | * Performs the needed symbol lookups and code relocations, | |
413 | * then registers the patched functions with ftrace. | |
414 | * | |
415 | * Return: 0 on success, otherwise error | |
416 | */ | |
417 | int klp_enable_patch(struct klp_patch *patch) | |
418 | { | |
419 | int ret; | |
420 | ||
421 | mutex_lock(&klp_mutex); | |
422 | ||
423 | if (!klp_is_patch_registered(patch)) { | |
424 | ret = -EINVAL; | |
425 | goto err; | |
426 | } | |
427 | ||
428 | ret = __klp_enable_patch(patch); | |
429 | ||
430 | err: | |
431 | mutex_unlock(&klp_mutex); | |
432 | return ret; | |
433 | } | |
434 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
435 | ||
436 | /* | |
437 | * Sysfs Interface | |
438 | * | |
439 | * /sys/kernel/livepatch | |
440 | * /sys/kernel/livepatch/<patch> | |
441 | * /sys/kernel/livepatch/<patch>/enabled | |
d83a7cb3 | 442 | * /sys/kernel/livepatch/<patch>/transition |
b700e7f0 | 443 | * /sys/kernel/livepatch/<patch>/<object> |
444f9e99 | 444 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 SJ |
445 | */ |
446 | ||
447 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
448 | const char *buf, size_t count) | |
449 | { | |
450 | struct klp_patch *patch; | |
451 | int ret; | |
68ae4b2b | 452 | bool enabled; |
b700e7f0 | 453 | |
68ae4b2b | 454 | ret = kstrtobool(buf, &enabled); |
b700e7f0 | 455 | if (ret) |
68ae4b2b | 456 | return ret; |
b700e7f0 SJ |
457 | |
458 | patch = container_of(kobj, struct klp_patch, kobj); | |
459 | ||
460 | mutex_lock(&klp_mutex); | |
461 | ||
3ec24776 JP |
462 | if (!klp_is_patch_registered(patch)) { |
463 | /* | |
464 | * Module with the patch could either disappear meanwhile or is | |
465 | * not properly initialized yet. | |
466 | */ | |
467 | ret = -EINVAL; | |
468 | goto err; | |
469 | } | |
470 | ||
68ae4b2b | 471 | if (patch->enabled == enabled) { |
b700e7f0 SJ |
472 | /* already in requested state */ |
473 | ret = -EINVAL; | |
474 | goto err; | |
475 | } | |
476 | ||
d83a7cb3 JP |
477 | if (patch == klp_transition_patch) { |
478 | klp_reverse_transition(); | |
479 | } else if (enabled) { | |
b700e7f0 SJ |
480 | ret = __klp_enable_patch(patch); |
481 | if (ret) | |
482 | goto err; | |
483 | } else { | |
484 | ret = __klp_disable_patch(patch); | |
485 | if (ret) | |
486 | goto err; | |
487 | } | |
488 | ||
489 | mutex_unlock(&klp_mutex); | |
490 | ||
491 | return count; | |
492 | ||
493 | err: | |
494 | mutex_unlock(&klp_mutex); | |
495 | return ret; | |
496 | } | |
497 | ||
498 | static ssize_t enabled_show(struct kobject *kobj, | |
499 | struct kobj_attribute *attr, char *buf) | |
500 | { | |
501 | struct klp_patch *patch; | |
502 | ||
503 | patch = container_of(kobj, struct klp_patch, kobj); | |
0dade9f3 | 504 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled); |
b700e7f0 SJ |
505 | } |
506 | ||
d83a7cb3 JP |
507 | static ssize_t transition_show(struct kobject *kobj, |
508 | struct kobj_attribute *attr, char *buf) | |
509 | { | |
510 | struct klp_patch *patch; | |
511 | ||
512 | patch = container_of(kobj, struct klp_patch, kobj); | |
513 | return snprintf(buf, PAGE_SIZE-1, "%d\n", | |
514 | patch == klp_transition_patch); | |
b700e7f0 SJ |
515 | } |
516 | ||
517 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); | |
d83a7cb3 | 518 | static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); |
b700e7f0 SJ |
519 | static struct attribute *klp_patch_attrs[] = { |
520 | &enabled_kobj_attr.attr, | |
d83a7cb3 | 521 | &transition_kobj_attr.attr, |
b700e7f0 SJ |
522 | NULL |
523 | }; | |
524 | ||
525 | static void klp_kobj_release_patch(struct kobject *kobj) | |
526 | { | |
3ec24776 JP |
527 | struct klp_patch *patch; |
528 | ||
529 | patch = container_of(kobj, struct klp_patch, kobj); | |
530 | complete(&patch->finish); | |
b700e7f0 SJ |
531 | } |
532 | ||
533 | static struct kobj_type klp_ktype_patch = { | |
534 | .release = klp_kobj_release_patch, | |
535 | .sysfs_ops = &kobj_sysfs_ops, | |
536 | .default_attrs = klp_patch_attrs, | |
537 | }; | |
538 | ||
cad706df MB |
539 | static void klp_kobj_release_object(struct kobject *kobj) |
540 | { | |
541 | } | |
542 | ||
543 | static struct kobj_type klp_ktype_object = { | |
544 | .release = klp_kobj_release_object, | |
545 | .sysfs_ops = &kobj_sysfs_ops, | |
546 | }; | |
547 | ||
b700e7f0 SJ |
548 | static void klp_kobj_release_func(struct kobject *kobj) |
549 | { | |
b700e7f0 SJ |
550 | } |
551 | ||
552 | static struct kobj_type klp_ktype_func = { | |
553 | .release = klp_kobj_release_func, | |
554 | .sysfs_ops = &kobj_sysfs_ops, | |
555 | }; | |
556 | ||
557 | /* | |
558 | * Free all functions' kobjects in the array up to some limit. When limit is | |
559 | * NULL, all kobjects are freed. | |
560 | */ | |
561 | static void klp_free_funcs_limited(struct klp_object *obj, | |
562 | struct klp_func *limit) | |
563 | { | |
564 | struct klp_func *func; | |
565 | ||
566 | for (func = obj->funcs; func->old_name && func != limit; func++) | |
567 | kobject_put(&func->kobj); | |
568 | } | |
569 | ||
570 | /* Clean up when a patched object is unloaded */ | |
571 | static void klp_free_object_loaded(struct klp_object *obj) | |
572 | { | |
573 | struct klp_func *func; | |
574 | ||
575 | obj->mod = NULL; | |
576 | ||
8cdd043a | 577 | klp_for_each_func(obj, func) |
b700e7f0 SJ |
578 | func->old_addr = 0; |
579 | } | |
580 | ||
581 | /* | |
582 | * Free all objects' kobjects in the array up to some limit. When limit is | |
583 | * NULL, all kobjects are freed. | |
584 | */ | |
585 | static void klp_free_objects_limited(struct klp_patch *patch, | |
586 | struct klp_object *limit) | |
587 | { | |
588 | struct klp_object *obj; | |
589 | ||
590 | for (obj = patch->objs; obj->funcs && obj != limit; obj++) { | |
591 | klp_free_funcs_limited(obj, NULL); | |
cad706df | 592 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
593 | } |
594 | } | |
595 | ||
596 | static void klp_free_patch(struct klp_patch *patch) | |
597 | { | |
598 | klp_free_objects_limited(patch, NULL); | |
599 | if (!list_empty(&patch->list)) | |
600 | list_del(&patch->list); | |
b700e7f0 SJ |
601 | } |
602 | ||
603 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
604 | { | |
f09d9086 MB |
605 | if (!func->old_name || !func->new_func) |
606 | return -EINVAL; | |
607 | ||
3c33f5b9 | 608 | INIT_LIST_HEAD(&func->stack_node); |
0dade9f3 | 609 | func->patched = false; |
d83a7cb3 | 610 | func->transition = false; |
b700e7f0 | 611 | |
444f9e99 CA |
612 | /* The format for the sysfs directory is <function,sympos> where sympos |
613 | * is the nth occurrence of this symbol in kallsyms for the patched | |
614 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
615 | * since a unique symbol will be the first occurrence. | |
616 | */ | |
3c33f5b9 | 617 | return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
444f9e99 CA |
618 | &obj->kobj, "%s,%lu", func->old_name, |
619 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
620 | } |
621 | ||
255e732c JY |
622 | /* Arches may override this to finish any remaining arch-specific tasks */ |
623 | void __weak arch_klp_init_object_loaded(struct klp_patch *patch, | |
624 | struct klp_object *obj) | |
625 | { | |
626 | } | |
627 | ||
b700e7f0 SJ |
628 | /* parts of the initialization that is done only when the object is loaded */ |
629 | static int klp_init_object_loaded(struct klp_patch *patch, | |
630 | struct klp_object *obj) | |
631 | { | |
632 | struct klp_func *func; | |
633 | int ret; | |
634 | ||
255e732c | 635 | module_disable_ro(patch->mod); |
425595a7 | 636 | ret = klp_write_object_relocations(patch->mod, obj); |
255e732c JY |
637 | if (ret) { |
638 | module_enable_ro(patch->mod, true); | |
425595a7 | 639 | return ret; |
255e732c JY |
640 | } |
641 | ||
642 | arch_klp_init_object_loaded(patch, obj); | |
643 | module_enable_ro(patch->mod, true); | |
b700e7f0 | 644 | |
8cdd043a | 645 | klp_for_each_func(obj, func) { |
b2b018ef CA |
646 | ret = klp_find_object_symbol(obj->name, func->old_name, |
647 | func->old_sympos, | |
648 | &func->old_addr); | |
b700e7f0 SJ |
649 | if (ret) |
650 | return ret; | |
f5e547f4 JP |
651 | |
652 | ret = kallsyms_lookup_size_offset(func->old_addr, | |
653 | &func->old_size, NULL); | |
654 | if (!ret) { | |
655 | pr_err("kallsyms size lookup failed for '%s'\n", | |
656 | func->old_name); | |
657 | return -ENOENT; | |
658 | } | |
659 | ||
660 | ret = kallsyms_lookup_size_offset((unsigned long)func->new_func, | |
661 | &func->new_size, NULL); | |
662 | if (!ret) { | |
663 | pr_err("kallsyms size lookup failed for '%s' replacement\n", | |
664 | func->old_name); | |
665 | return -ENOENT; | |
666 | } | |
b700e7f0 SJ |
667 | } |
668 | ||
669 | return 0; | |
670 | } | |
671 | ||
672 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
673 | { | |
674 | struct klp_func *func; | |
675 | int ret; | |
676 | const char *name; | |
677 | ||
678 | if (!obj->funcs) | |
679 | return -EINVAL; | |
680 | ||
0dade9f3 | 681 | obj->patched = false; |
8cb2c2dc | 682 | obj->mod = NULL; |
b700e7f0 SJ |
683 | |
684 | klp_find_object_module(obj); | |
685 | ||
686 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
cad706df MB |
687 | ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object, |
688 | &patch->kobj, "%s", name); | |
689 | if (ret) | |
690 | return ret; | |
b700e7f0 | 691 | |
8cdd043a | 692 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
693 | ret = klp_init_func(obj, func); |
694 | if (ret) | |
695 | goto free; | |
696 | } | |
697 | ||
698 | if (klp_is_object_loaded(obj)) { | |
699 | ret = klp_init_object_loaded(patch, obj); | |
700 | if (ret) | |
701 | goto free; | |
702 | } | |
703 | ||
704 | return 0; | |
705 | ||
706 | free: | |
707 | klp_free_funcs_limited(obj, func); | |
cad706df | 708 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
709 | return ret; |
710 | } | |
711 | ||
712 | static int klp_init_patch(struct klp_patch *patch) | |
713 | { | |
714 | struct klp_object *obj; | |
715 | int ret; | |
716 | ||
717 | if (!patch->objs) | |
718 | return -EINVAL; | |
719 | ||
720 | mutex_lock(&klp_mutex); | |
721 | ||
0dade9f3 | 722 | patch->enabled = false; |
3ec24776 | 723 | init_completion(&patch->finish); |
b700e7f0 SJ |
724 | |
725 | ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, | |
e0b561ee | 726 | klp_root_kobj, "%s", patch->mod->name); |
3ec24776 JP |
727 | if (ret) { |
728 | mutex_unlock(&klp_mutex); | |
729 | return ret; | |
730 | } | |
b700e7f0 | 731 | |
8cdd043a | 732 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
733 | ret = klp_init_object(patch, obj); |
734 | if (ret) | |
735 | goto free; | |
736 | } | |
737 | ||
99590ba5 | 738 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
739 | |
740 | mutex_unlock(&klp_mutex); | |
741 | ||
742 | return 0; | |
743 | ||
744 | free: | |
745 | klp_free_objects_limited(patch, obj); | |
3ec24776 | 746 | |
b700e7f0 | 747 | mutex_unlock(&klp_mutex); |
3ec24776 JP |
748 | |
749 | kobject_put(&patch->kobj); | |
750 | wait_for_completion(&patch->finish); | |
751 | ||
b700e7f0 SJ |
752 | return ret; |
753 | } | |
754 | ||
755 | /** | |
756 | * klp_unregister_patch() - unregisters a patch | |
757 | * @patch: Disabled patch to be unregistered | |
758 | * | |
759 | * Frees the data structures and removes the sysfs interface. | |
760 | * | |
761 | * Return: 0 on success, otherwise error | |
762 | */ | |
763 | int klp_unregister_patch(struct klp_patch *patch) | |
764 | { | |
3ec24776 | 765 | int ret; |
b700e7f0 SJ |
766 | |
767 | mutex_lock(&klp_mutex); | |
768 | ||
769 | if (!klp_is_patch_registered(patch)) { | |
770 | ret = -EINVAL; | |
3ec24776 | 771 | goto err; |
b700e7f0 SJ |
772 | } |
773 | ||
0dade9f3 | 774 | if (patch->enabled) { |
b700e7f0 | 775 | ret = -EBUSY; |
3ec24776 | 776 | goto err; |
b700e7f0 SJ |
777 | } |
778 | ||
779 | klp_free_patch(patch); | |
780 | ||
3ec24776 JP |
781 | mutex_unlock(&klp_mutex); |
782 | ||
783 | kobject_put(&patch->kobj); | |
784 | wait_for_completion(&patch->finish); | |
785 | ||
786 | return 0; | |
787 | err: | |
b700e7f0 SJ |
788 | mutex_unlock(&klp_mutex); |
789 | return ret; | |
790 | } | |
791 | EXPORT_SYMBOL_GPL(klp_unregister_patch); | |
792 | ||
793 | /** | |
794 | * klp_register_patch() - registers a patch | |
795 | * @patch: Patch to be registered | |
796 | * | |
797 | * Initializes the data structure associated with the patch and | |
798 | * creates the sysfs interface. | |
799 | * | |
3ec24776 JP |
800 | * There is no need to take the reference on the patch module here. It is done |
801 | * later when the patch is enabled. | |
802 | * | |
b700e7f0 SJ |
803 | * Return: 0 on success, otherwise error |
804 | */ | |
805 | int klp_register_patch(struct klp_patch *patch) | |
806 | { | |
b700e7f0 SJ |
807 | if (!patch || !patch->mod) |
808 | return -EINVAL; | |
809 | ||
425595a7 | 810 | if (!is_livepatch_module(patch->mod)) { |
77f8f39a | 811 | pr_err("module %s is not marked as a livepatch module\n", |
425595a7 JY |
812 | patch->mod->name); |
813 | return -EINVAL; | |
814 | } | |
815 | ||
b700e7f0 SJ |
816 | if (!klp_initialized()) |
817 | return -ENODEV; | |
818 | ||
b700e7f0 | 819 | /* |
d83a7cb3 JP |
820 | * Architectures without reliable stack traces have to set |
821 | * patch->immediate because there's currently no way to patch kthreads | |
822 | * with the consistency model. | |
b700e7f0 | 823 | */ |
d83a7cb3 JP |
824 | if (!klp_have_reliable_stack() && !patch->immediate) { |
825 | pr_err("This architecture doesn't have support for the livepatch consistency model.\n"); | |
826 | return -ENOSYS; | |
827 | } | |
b700e7f0 | 828 | |
3ec24776 | 829 | return klp_init_patch(patch); |
b700e7f0 SJ |
830 | } |
831 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
832 | ||
7e545d6e | 833 | int klp_module_coming(struct module *mod) |
b700e7f0 | 834 | { |
b700e7f0 | 835 | int ret; |
7e545d6e JY |
836 | struct klp_patch *patch; |
837 | struct klp_object *obj; | |
b700e7f0 | 838 | |
7e545d6e JY |
839 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
840 | return -EINVAL; | |
b700e7f0 | 841 | |
7e545d6e JY |
842 | mutex_lock(&klp_mutex); |
843 | /* | |
844 | * Each module has to know that klp_module_coming() | |
845 | * has been called. We never know what module will | |
846 | * get patched by a new patch. | |
847 | */ | |
848 | mod->klp_alive = true; | |
b700e7f0 | 849 | |
7e545d6e JY |
850 | list_for_each_entry(patch, &klp_patches, list) { |
851 | klp_for_each_object(patch, obj) { | |
852 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
853 | continue; | |
b700e7f0 | 854 | |
7e545d6e | 855 | obj->mod = mod; |
b700e7f0 | 856 | |
7e545d6e JY |
857 | ret = klp_init_object_loaded(patch, obj); |
858 | if (ret) { | |
859 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
860 | patch->mod->name, obj->mod->name, ret); | |
861 | goto err; | |
862 | } | |
b700e7f0 | 863 | |
d83a7cb3 JP |
864 | /* |
865 | * Only patch the module if the patch is enabled or is | |
866 | * in transition. | |
867 | */ | |
868 | if (!patch->enabled && patch != klp_transition_patch) | |
7e545d6e JY |
869 | break; |
870 | ||
871 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
872 | patch->mod->name, obj->mod->name); | |
873 | ||
0dade9f3 | 874 | ret = klp_patch_object(obj); |
7e545d6e JY |
875 | if (ret) { |
876 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
877 | patch->mod->name, obj->mod->name, ret); | |
878 | goto err; | |
879 | } | |
880 | ||
881 | break; | |
882 | } | |
883 | } | |
b700e7f0 | 884 | |
7e545d6e | 885 | mutex_unlock(&klp_mutex); |
b700e7f0 | 886 | |
7e545d6e | 887 | return 0; |
b700e7f0 | 888 | |
7e545d6e JY |
889 | err: |
890 | /* | |
891 | * If a patch is unsuccessfully applied, return | |
892 | * error to the module loader. | |
893 | */ | |
894 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
895 | patch->mod->name, obj->mod->name, obj->mod->name); | |
896 | mod->klp_alive = false; | |
b700e7f0 | 897 | klp_free_object_loaded(obj); |
7e545d6e JY |
898 | mutex_unlock(&klp_mutex); |
899 | ||
900 | return ret; | |
b700e7f0 SJ |
901 | } |
902 | ||
7e545d6e | 903 | void klp_module_going(struct module *mod) |
b700e7f0 | 904 | { |
b700e7f0 SJ |
905 | struct klp_patch *patch; |
906 | struct klp_object *obj; | |
907 | ||
7e545d6e JY |
908 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
909 | mod->state != MODULE_STATE_COMING)) | |
910 | return; | |
b700e7f0 SJ |
911 | |
912 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 913 | /* |
7e545d6e JY |
914 | * Each module has to know that klp_module_going() |
915 | * has been called. We never know what module will | |
916 | * get patched by a new patch. | |
8cb2c2dc | 917 | */ |
7e545d6e | 918 | mod->klp_alive = false; |
8cb2c2dc | 919 | |
b700e7f0 | 920 | list_for_each_entry(patch, &klp_patches, list) { |
8cdd043a | 921 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
922 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) |
923 | continue; | |
924 | ||
d83a7cb3 JP |
925 | /* |
926 | * Only unpatch the module if the patch is enabled or | |
927 | * is in transition. | |
928 | */ | |
929 | if (patch->enabled || patch == klp_transition_patch) { | |
7e545d6e JY |
930 | pr_notice("reverting patch '%s' on unloading module '%s'\n", |
931 | patch->mod->name, obj->mod->name); | |
0dade9f3 | 932 | klp_unpatch_object(obj); |
7e545d6e | 933 | } |
b700e7f0 | 934 | |
7e545d6e | 935 | klp_free_object_loaded(obj); |
b700e7f0 SJ |
936 | break; |
937 | } | |
938 | } | |
939 | ||
940 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
941 | } |
942 | ||
26029d88 | 943 | static int __init klp_init(void) |
b700e7f0 SJ |
944 | { |
945 | int ret; | |
946 | ||
b9dfe0be JK |
947 | ret = klp_check_compiler_support(); |
948 | if (ret) { | |
949 | pr_info("Your compiler is too old; turning off.\n"); | |
950 | return -EINVAL; | |
951 | } | |
952 | ||
b700e7f0 | 953 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
954 | if (!klp_root_kobj) |
955 | return -ENOMEM; | |
b700e7f0 SJ |
956 | |
957 | return 0; | |
b700e7f0 SJ |
958 | } |
959 | ||
960 | module_init(klp_init); |