Commit | Line | Data |
---|---|---|
b700e7f0 SJ |
1 | /* |
2 | * core.c - Kernel Live Patching Core | |
3 | * | |
4 | * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> | |
5 | * Copyright (C) 2014 SUSE | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version 2 | |
10 | * of the License, or (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, see <http://www.gnu.org/licenses/>. | |
19 | */ | |
20 | ||
21 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
22 | ||
23 | #include <linux/module.h> | |
24 | #include <linux/kernel.h> | |
25 | #include <linux/mutex.h> | |
26 | #include <linux/slab.h> | |
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 | ||
b700e7f0 SJ |
57 | /* sets obj->mod if object is not vmlinux and module is found */ |
58 | static void klp_find_object_module(struct klp_object *obj) | |
59 | { | |
8cb2c2dc PM |
60 | struct module *mod; |
61 | ||
b700e7f0 SJ |
62 | if (!klp_is_module(obj)) |
63 | return; | |
64 | ||
65 | mutex_lock(&module_mutex); | |
66 | /* | |
8cb2c2dc PM |
67 | * We do not want to block removal of patched modules and therefore |
68 | * we do not take a reference here. The patches are removed by | |
7e545d6e | 69 | * klp_module_going() instead. |
8cb2c2dc PM |
70 | */ |
71 | mod = find_module(obj->name); | |
72 | /* | |
7e545d6e JY |
73 | * Do not mess work of klp_module_coming() and klp_module_going(). |
74 | * Note that the patch might still be needed before klp_module_going() | |
8cb2c2dc PM |
75 | * is called. Module functions can be called even in the GOING state |
76 | * until mod->exit() finishes. This is especially important for | |
77 | * patches that modify semantic of the functions. | |
b700e7f0 | 78 | */ |
8cb2c2dc PM |
79 | if (mod && mod->klp_alive) |
80 | obj->mod = mod; | |
81 | ||
b700e7f0 SJ |
82 | mutex_unlock(&module_mutex); |
83 | } | |
84 | ||
b700e7f0 SJ |
85 | static bool klp_is_patch_registered(struct klp_patch *patch) |
86 | { | |
87 | struct klp_patch *mypatch; | |
88 | ||
89 | list_for_each_entry(mypatch, &klp_patches, list) | |
90 | if (mypatch == patch) | |
91 | return true; | |
92 | ||
93 | return false; | |
94 | } | |
95 | ||
96 | static bool klp_initialized(void) | |
97 | { | |
e76ff06a | 98 | return !!klp_root_kobj; |
b700e7f0 SJ |
99 | } |
100 | ||
101 | struct klp_find_arg { | |
102 | const char *objname; | |
103 | const char *name; | |
104 | unsigned long addr; | |
b700e7f0 | 105 | unsigned long count; |
b2b018ef | 106 | unsigned long pos; |
b700e7f0 SJ |
107 | }; |
108 | ||
109 | static int klp_find_callback(void *data, const char *name, | |
110 | struct module *mod, unsigned long addr) | |
111 | { | |
112 | struct klp_find_arg *args = data; | |
113 | ||
114 | if ((mod && !args->objname) || (!mod && args->objname)) | |
115 | return 0; | |
116 | ||
117 | if (strcmp(args->name, name)) | |
118 | return 0; | |
119 | ||
120 | if (args->objname && strcmp(args->objname, mod->name)) | |
121 | return 0; | |
122 | ||
b700e7f0 SJ |
123 | args->addr = addr; |
124 | args->count++; | |
125 | ||
b2b018ef CA |
126 | /* |
127 | * Finish the search when the symbol is found for the desired position | |
128 | * or the position is not defined for a non-unique symbol. | |
129 | */ | |
130 | if ((args->pos && (args->count == args->pos)) || | |
131 | (!args->pos && (args->count > 1))) | |
132 | return 1; | |
133 | ||
b700e7f0 SJ |
134 | return 0; |
135 | } | |
136 | ||
137 | static int klp_find_object_symbol(const char *objname, const char *name, | |
b2b018ef | 138 | unsigned long sympos, unsigned long *addr) |
b700e7f0 SJ |
139 | { |
140 | struct klp_find_arg args = { | |
141 | .objname = objname, | |
142 | .name = name, | |
143 | .addr = 0, | |
b2b018ef CA |
144 | .count = 0, |
145 | .pos = sympos, | |
b700e7f0 SJ |
146 | }; |
147 | ||
9a1bd63c | 148 | mutex_lock(&module_mutex); |
72f04b50 ZC |
149 | if (objname) |
150 | module_kallsyms_on_each_symbol(klp_find_callback, &args); | |
151 | else | |
152 | kallsyms_on_each_symbol(klp_find_callback, &args); | |
9a1bd63c | 153 | mutex_unlock(&module_mutex); |
b700e7f0 | 154 | |
b2b018ef CA |
155 | /* |
156 | * Ensure an address was found. If sympos is 0, ensure symbol is unique; | |
157 | * otherwise ensure the symbol position count matches sympos. | |
158 | */ | |
159 | if (args.addr == 0) | |
b700e7f0 | 160 | pr_err("symbol '%s' not found in symbol table\n", name); |
b2b018ef | 161 | else if (args.count > 1 && sympos == 0) { |
f995b5f7 PM |
162 | pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n", |
163 | name, objname); | |
b2b018ef CA |
164 | } else if (sympos != args.count && sympos > 0) { |
165 | pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n", | |
166 | sympos, name, objname ? objname : "vmlinux"); | |
167 | } else { | |
b700e7f0 SJ |
168 | *addr = args.addr; |
169 | return 0; | |
170 | } | |
171 | ||
172 | *addr = 0; | |
173 | return -EINVAL; | |
174 | } | |
175 | ||
425595a7 | 176 | static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod) |
b700e7f0 | 177 | { |
425595a7 JY |
178 | int i, cnt, vmlinux, ret; |
179 | char objname[MODULE_NAME_LEN]; | |
180 | char symname[KSYM_NAME_LEN]; | |
181 | char *strtab = pmod->core_kallsyms.strtab; | |
182 | Elf_Rela *relas; | |
183 | Elf_Sym *sym; | |
184 | unsigned long sympos, addr; | |
b700e7f0 | 185 | |
b2b018ef | 186 | /* |
425595a7 JY |
187 | * Since the field widths for objname and symname in the sscanf() |
188 | * call are hard-coded and correspond to MODULE_NAME_LEN and | |
189 | * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN | |
190 | * and KSYM_NAME_LEN have the values we expect them to have. | |
191 | * | |
192 | * Because the value of MODULE_NAME_LEN can differ among architectures, | |
193 | * we use the smallest/strictest upper bound possible (56, based on | |
194 | * the current definition of MODULE_NAME_LEN) to prevent overflows. | |
b2b018ef | 195 | */ |
425595a7 JY |
196 | BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); |
197 | ||
198 | relas = (Elf_Rela *) relasec->sh_addr; | |
199 | /* For each rela in this klp relocation section */ | |
200 | for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { | |
201 | sym = pmod->core_kallsyms.symtab + ELF_R_SYM(relas[i].r_info); | |
202 | if (sym->st_shndx != SHN_LIVEPATCH) { | |
77f8f39a | 203 | pr_err("symbol %s is not marked as a livepatch symbol\n", |
425595a7 JY |
204 | strtab + sym->st_name); |
205 | return -EINVAL; | |
206 | } | |
207 | ||
208 | /* Format: .klp.sym.objname.symname,sympos */ | |
209 | cnt = sscanf(strtab + sym->st_name, | |
210 | ".klp.sym.%55[^.].%127[^,],%lu", | |
211 | objname, symname, &sympos); | |
212 | if (cnt != 3) { | |
77f8f39a | 213 | pr_err("symbol %s has an incorrectly formatted name\n", |
425595a7 JY |
214 | strtab + sym->st_name); |
215 | return -EINVAL; | |
216 | } | |
217 | ||
218 | /* klp_find_object_symbol() treats a NULL objname as vmlinux */ | |
219 | vmlinux = !strcmp(objname, "vmlinux"); | |
220 | ret = klp_find_object_symbol(vmlinux ? NULL : objname, | |
221 | symname, sympos, &addr); | |
222 | if (ret) | |
223 | return ret; | |
224 | ||
225 | sym->st_value = addr; | |
226 | } | |
227 | ||
228 | return 0; | |
b700e7f0 SJ |
229 | } |
230 | ||
231 | static int klp_write_object_relocations(struct module *pmod, | |
232 | struct klp_object *obj) | |
233 | { | |
425595a7 JY |
234 | int i, cnt, ret = 0; |
235 | const char *objname, *secname; | |
236 | char sec_objname[MODULE_NAME_LEN]; | |
237 | Elf_Shdr *sec; | |
b700e7f0 SJ |
238 | |
239 | if (WARN_ON(!klp_is_object_loaded(obj))) | |
240 | return -EINVAL; | |
241 | ||
425595a7 | 242 | objname = klp_is_module(obj) ? obj->name : "vmlinux"; |
b700e7f0 | 243 | |
425595a7 JY |
244 | /* For each klp relocation section */ |
245 | for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) { | |
246 | sec = pmod->klp_info->sechdrs + i; | |
247 | secname = pmod->klp_info->secstrings + sec->sh_name; | |
248 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
249 | continue; | |
b56b36ee | 250 | |
425595a7 JY |
251 | /* |
252 | * Format: .klp.rela.sec_objname.section_name | |
253 | * See comment in klp_resolve_symbols() for an explanation | |
254 | * of the selected field width value. | |
255 | */ | |
256 | cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname); | |
257 | if (cnt != 1) { | |
77f8f39a | 258 | pr_err("section %s has an incorrectly formatted name\n", |
425595a7 JY |
259 | secname); |
260 | ret = -EINVAL; | |
261 | break; | |
262 | } | |
b56b36ee | 263 | |
425595a7 JY |
264 | if (strcmp(objname, sec_objname)) |
265 | continue; | |
b56b36ee | 266 | |
425595a7 | 267 | ret = klp_resolve_symbols(sec, pmod); |
064c89df | 268 | if (ret) |
425595a7 | 269 | break; |
064c89df | 270 | |
425595a7 JY |
271 | ret = apply_relocate_add(pmod->klp_info->sechdrs, |
272 | pmod->core_kallsyms.strtab, | |
273 | pmod->klp_info->symndx, i, pmod); | |
274 | if (ret) | |
275 | break; | |
b700e7f0 SJ |
276 | } |
277 | ||
b56b36ee | 278 | return ret; |
b700e7f0 SJ |
279 | } |
280 | ||
b700e7f0 SJ |
281 | static int __klp_disable_patch(struct klp_patch *patch) |
282 | { | |
93862e38 JL |
283 | struct klp_object *obj; |
284 | ||
89a9a1c1 PM |
285 | if (WARN_ON(!patch->enabled)) |
286 | return -EINVAL; | |
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 | |
93862e38 | 298 | klp_for_each_object(patch, obj) |
89a9a1c1 | 299 | if (obj->patched) |
93862e38 JL |
300 | klp_pre_unpatch_callback(obj); |
301 | ||
d83a7cb3 JP |
302 | /* |
303 | * Enforce the order of the func->transition writes in | |
304 | * klp_init_transition() and the TIF_PATCH_PENDING writes in | |
305 | * klp_start_transition(). In the rare case where klp_ftrace_handler() | |
306 | * is called shortly after klp_update_patch_state() switches the task, | |
307 | * this ensures the handler sees that func->transition is set. | |
308 | */ | |
309 | smp_wmb(); | |
b700e7f0 | 310 | |
d83a7cb3 JP |
311 | klp_start_transition(); |
312 | klp_try_complete_transition(); | |
0dade9f3 | 313 | patch->enabled = false; |
b700e7f0 SJ |
314 | |
315 | return 0; | |
316 | } | |
317 | ||
318 | /** | |
319 | * klp_disable_patch() - disables a registered patch | |
320 | * @patch: The registered, enabled patch to be disabled | |
321 | * | |
322 | * Unregisters the patched functions from ftrace. | |
323 | * | |
324 | * Return: 0 on success, otherwise error | |
325 | */ | |
326 | int klp_disable_patch(struct klp_patch *patch) | |
327 | { | |
328 | int ret; | |
329 | ||
330 | mutex_lock(&klp_mutex); | |
331 | ||
332 | if (!klp_is_patch_registered(patch)) { | |
333 | ret = -EINVAL; | |
334 | goto err; | |
335 | } | |
336 | ||
0dade9f3 | 337 | if (!patch->enabled) { |
b700e7f0 SJ |
338 | ret = -EINVAL; |
339 | goto err; | |
340 | } | |
341 | ||
342 | ret = __klp_disable_patch(patch); | |
343 | ||
344 | err: | |
345 | mutex_unlock(&klp_mutex); | |
346 | return ret; | |
347 | } | |
348 | EXPORT_SYMBOL_GPL(klp_disable_patch); | |
349 | ||
350 | static int __klp_enable_patch(struct klp_patch *patch) | |
351 | { | |
352 | struct klp_object *obj; | |
353 | int ret; | |
354 | ||
d83a7cb3 JP |
355 | if (klp_transition_patch) |
356 | return -EBUSY; | |
357 | ||
0dade9f3 | 358 | if (WARN_ON(patch->enabled)) |
b700e7f0 SJ |
359 | return -EINVAL; |
360 | ||
83a90bb1 JP |
361 | /* enforce stacking: only the first disabled patch can be enabled */ |
362 | if (patch->list.prev != &klp_patches && | |
0dade9f3 | 363 | !list_prev_entry(patch, list)->enabled) |
83a90bb1 JP |
364 | return -EBUSY; |
365 | ||
3ec24776 JP |
366 | /* |
367 | * A reference is taken on the patch module to prevent it from being | |
368 | * unloaded. | |
3ec24776 JP |
369 | */ |
370 | if (!try_module_get(patch->mod)) | |
371 | return -ENODEV; | |
372 | ||
b700e7f0 SJ |
373 | pr_notice("enabling patch '%s'\n", patch->mod->name); |
374 | ||
d83a7cb3 JP |
375 | klp_init_transition(patch, KLP_PATCHED); |
376 | ||
377 | /* | |
378 | * Enforce the order of the func->transition writes in | |
379 | * klp_init_transition() and the ops->func_stack writes in | |
380 | * klp_patch_object(), so that klp_ftrace_handler() will see the | |
381 | * func->transition updates before the handler is registered and the | |
382 | * new funcs become visible to the handler. | |
383 | */ | |
384 | smp_wmb(); | |
385 | ||
8cdd043a | 386 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
387 | if (!klp_is_object_loaded(obj)) |
388 | continue; | |
389 | ||
93862e38 | 390 | ret = klp_pre_patch_callback(obj); |
d83a7cb3 | 391 | if (ret) { |
93862e38 JL |
392 | pr_warn("pre-patch callback failed for object '%s'\n", |
393 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
394 | goto err; | |
395 | } | |
d83a7cb3 | 396 | |
93862e38 JL |
397 | ret = klp_patch_object(obj); |
398 | if (ret) { | |
399 | pr_warn("failed to patch object '%s'\n", | |
400 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
401 | goto err; | |
d83a7cb3 | 402 | } |
b700e7f0 SJ |
403 | } |
404 | ||
d83a7cb3 JP |
405 | klp_start_transition(); |
406 | klp_try_complete_transition(); | |
0dade9f3 | 407 | patch->enabled = true; |
b700e7f0 SJ |
408 | |
409 | return 0; | |
93862e38 JL |
410 | err: |
411 | pr_warn("failed to enable patch '%s'\n", patch->mod->name); | |
412 | ||
413 | klp_cancel_transition(); | |
414 | return ret; | |
b700e7f0 SJ |
415 | } |
416 | ||
417 | /** | |
418 | * klp_enable_patch() - enables a registered patch | |
419 | * @patch: The registered, disabled patch to be enabled | |
420 | * | |
421 | * Performs the needed symbol lookups and code relocations, | |
422 | * then registers the patched functions with ftrace. | |
423 | * | |
424 | * Return: 0 on success, otherwise error | |
425 | */ | |
426 | int klp_enable_patch(struct klp_patch *patch) | |
427 | { | |
428 | int ret; | |
429 | ||
430 | mutex_lock(&klp_mutex); | |
431 | ||
432 | if (!klp_is_patch_registered(patch)) { | |
433 | ret = -EINVAL; | |
434 | goto err; | |
435 | } | |
436 | ||
437 | ret = __klp_enable_patch(patch); | |
438 | ||
439 | err: | |
440 | mutex_unlock(&klp_mutex); | |
441 | return ret; | |
442 | } | |
443 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
444 | ||
445 | /* | |
446 | * Sysfs Interface | |
447 | * | |
448 | * /sys/kernel/livepatch | |
449 | * /sys/kernel/livepatch/<patch> | |
450 | * /sys/kernel/livepatch/<patch>/enabled | |
d83a7cb3 | 451 | * /sys/kernel/livepatch/<patch>/transition |
43347d56 | 452 | * /sys/kernel/livepatch/<patch>/signal |
c99a2be7 | 453 | * /sys/kernel/livepatch/<patch>/force |
b700e7f0 | 454 | * /sys/kernel/livepatch/<patch>/<object> |
444f9e99 | 455 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 SJ |
456 | */ |
457 | ||
458 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
459 | const char *buf, size_t count) | |
460 | { | |
461 | struct klp_patch *patch; | |
462 | int ret; | |
68ae4b2b | 463 | bool enabled; |
b700e7f0 | 464 | |
68ae4b2b | 465 | ret = kstrtobool(buf, &enabled); |
b700e7f0 | 466 | if (ret) |
68ae4b2b | 467 | return ret; |
b700e7f0 SJ |
468 | |
469 | patch = container_of(kobj, struct klp_patch, kobj); | |
470 | ||
471 | mutex_lock(&klp_mutex); | |
472 | ||
3ec24776 JP |
473 | if (!klp_is_patch_registered(patch)) { |
474 | /* | |
475 | * Module with the patch could either disappear meanwhile or is | |
476 | * not properly initialized yet. | |
477 | */ | |
478 | ret = -EINVAL; | |
479 | goto err; | |
480 | } | |
481 | ||
68ae4b2b | 482 | if (patch->enabled == enabled) { |
b700e7f0 SJ |
483 | /* already in requested state */ |
484 | ret = -EINVAL; | |
485 | goto err; | |
486 | } | |
487 | ||
d83a7cb3 JP |
488 | if (patch == klp_transition_patch) { |
489 | klp_reverse_transition(); | |
490 | } else if (enabled) { | |
b700e7f0 SJ |
491 | ret = __klp_enable_patch(patch); |
492 | if (ret) | |
493 | goto err; | |
494 | } else { | |
495 | ret = __klp_disable_patch(patch); | |
496 | if (ret) | |
497 | goto err; | |
498 | } | |
499 | ||
500 | mutex_unlock(&klp_mutex); | |
501 | ||
502 | return count; | |
503 | ||
504 | err: | |
505 | mutex_unlock(&klp_mutex); | |
506 | return ret; | |
507 | } | |
508 | ||
509 | static ssize_t enabled_show(struct kobject *kobj, | |
510 | struct kobj_attribute *attr, char *buf) | |
511 | { | |
512 | struct klp_patch *patch; | |
513 | ||
514 | patch = container_of(kobj, struct klp_patch, kobj); | |
0dade9f3 | 515 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled); |
b700e7f0 SJ |
516 | } |
517 | ||
d83a7cb3 JP |
518 | static ssize_t transition_show(struct kobject *kobj, |
519 | struct kobj_attribute *attr, char *buf) | |
520 | { | |
521 | struct klp_patch *patch; | |
522 | ||
523 | patch = container_of(kobj, struct klp_patch, kobj); | |
524 | return snprintf(buf, PAGE_SIZE-1, "%d\n", | |
525 | patch == klp_transition_patch); | |
b700e7f0 SJ |
526 | } |
527 | ||
43347d56 MB |
528 | static ssize_t signal_store(struct kobject *kobj, struct kobj_attribute *attr, |
529 | const char *buf, size_t count) | |
530 | { | |
531 | struct klp_patch *patch; | |
532 | int ret; | |
533 | bool val; | |
534 | ||
43347d56 MB |
535 | ret = kstrtobool(buf, &val); |
536 | if (ret) | |
537 | return ret; | |
538 | ||
8869016d MB |
539 | if (!val) |
540 | return count; | |
541 | ||
542 | mutex_lock(&klp_mutex); | |
543 | ||
544 | patch = container_of(kobj, struct klp_patch, kobj); | |
545 | if (patch != klp_transition_patch) { | |
546 | mutex_unlock(&klp_mutex); | |
547 | return -EINVAL; | |
548 | } | |
549 | ||
550 | klp_send_signals(); | |
551 | ||
552 | mutex_unlock(&klp_mutex); | |
43347d56 MB |
553 | |
554 | return count; | |
555 | } | |
556 | ||
c99a2be7 MB |
557 | static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, |
558 | const char *buf, size_t count) | |
559 | { | |
560 | struct klp_patch *patch; | |
561 | int ret; | |
562 | bool val; | |
563 | ||
c99a2be7 MB |
564 | ret = kstrtobool(buf, &val); |
565 | if (ret) | |
566 | return ret; | |
567 | ||
8869016d MB |
568 | if (!val) |
569 | return count; | |
570 | ||
571 | mutex_lock(&klp_mutex); | |
572 | ||
573 | patch = container_of(kobj, struct klp_patch, kobj); | |
574 | if (patch != klp_transition_patch) { | |
575 | mutex_unlock(&klp_mutex); | |
576 | return -EINVAL; | |
577 | } | |
578 | ||
579 | klp_force_transition(); | |
580 | ||
581 | mutex_unlock(&klp_mutex); | |
c99a2be7 MB |
582 | |
583 | return count; | |
584 | } | |
585 | ||
b700e7f0 | 586 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); |
d83a7cb3 | 587 | static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); |
43347d56 | 588 | static struct kobj_attribute signal_kobj_attr = __ATTR_WO(signal); |
c99a2be7 | 589 | static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); |
b700e7f0 SJ |
590 | static struct attribute *klp_patch_attrs[] = { |
591 | &enabled_kobj_attr.attr, | |
d83a7cb3 | 592 | &transition_kobj_attr.attr, |
43347d56 | 593 | &signal_kobj_attr.attr, |
c99a2be7 | 594 | &force_kobj_attr.attr, |
b700e7f0 SJ |
595 | NULL |
596 | }; | |
597 | ||
598 | static void klp_kobj_release_patch(struct kobject *kobj) | |
599 | { | |
3ec24776 JP |
600 | struct klp_patch *patch; |
601 | ||
602 | patch = container_of(kobj, struct klp_patch, kobj); | |
603 | complete(&patch->finish); | |
b700e7f0 SJ |
604 | } |
605 | ||
606 | static struct kobj_type klp_ktype_patch = { | |
607 | .release = klp_kobj_release_patch, | |
608 | .sysfs_ops = &kobj_sysfs_ops, | |
609 | .default_attrs = klp_patch_attrs, | |
610 | }; | |
611 | ||
cad706df MB |
612 | static void klp_kobj_release_object(struct kobject *kobj) |
613 | { | |
614 | } | |
615 | ||
616 | static struct kobj_type klp_ktype_object = { | |
617 | .release = klp_kobj_release_object, | |
618 | .sysfs_ops = &kobj_sysfs_ops, | |
619 | }; | |
620 | ||
b700e7f0 SJ |
621 | static void klp_kobj_release_func(struct kobject *kobj) |
622 | { | |
b700e7f0 SJ |
623 | } |
624 | ||
625 | static struct kobj_type klp_ktype_func = { | |
626 | .release = klp_kobj_release_func, | |
627 | .sysfs_ops = &kobj_sysfs_ops, | |
628 | }; | |
629 | ||
630 | /* | |
631 | * Free all functions' kobjects in the array up to some limit. When limit is | |
632 | * NULL, all kobjects are freed. | |
633 | */ | |
634 | static void klp_free_funcs_limited(struct klp_object *obj, | |
635 | struct klp_func *limit) | |
636 | { | |
637 | struct klp_func *func; | |
638 | ||
639 | for (func = obj->funcs; func->old_name && func != limit; func++) | |
640 | kobject_put(&func->kobj); | |
641 | } | |
642 | ||
643 | /* Clean up when a patched object is unloaded */ | |
644 | static void klp_free_object_loaded(struct klp_object *obj) | |
645 | { | |
646 | struct klp_func *func; | |
647 | ||
648 | obj->mod = NULL; | |
649 | ||
8cdd043a | 650 | klp_for_each_func(obj, func) |
b700e7f0 SJ |
651 | func->old_addr = 0; |
652 | } | |
653 | ||
654 | /* | |
655 | * Free all objects' kobjects in the array up to some limit. When limit is | |
656 | * NULL, all kobjects are freed. | |
657 | */ | |
658 | static void klp_free_objects_limited(struct klp_patch *patch, | |
659 | struct klp_object *limit) | |
660 | { | |
661 | struct klp_object *obj; | |
662 | ||
663 | for (obj = patch->objs; obj->funcs && obj != limit; obj++) { | |
664 | klp_free_funcs_limited(obj, NULL); | |
cad706df | 665 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
666 | } |
667 | } | |
668 | ||
669 | static void klp_free_patch(struct klp_patch *patch) | |
670 | { | |
671 | klp_free_objects_limited(patch, NULL); | |
672 | if (!list_empty(&patch->list)) | |
673 | list_del(&patch->list); | |
b700e7f0 SJ |
674 | } |
675 | ||
676 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
677 | { | |
f09d9086 MB |
678 | if (!func->old_name || !func->new_func) |
679 | return -EINVAL; | |
680 | ||
3c33f5b9 | 681 | INIT_LIST_HEAD(&func->stack_node); |
0dade9f3 | 682 | func->patched = false; |
d83a7cb3 | 683 | func->transition = false; |
b700e7f0 | 684 | |
444f9e99 CA |
685 | /* The format for the sysfs directory is <function,sympos> where sympos |
686 | * is the nth occurrence of this symbol in kallsyms for the patched | |
687 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
688 | * since a unique symbol will be the first occurrence. | |
689 | */ | |
3c33f5b9 | 690 | return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
444f9e99 CA |
691 | &obj->kobj, "%s,%lu", func->old_name, |
692 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
693 | } |
694 | ||
255e732c JY |
695 | /* Arches may override this to finish any remaining arch-specific tasks */ |
696 | void __weak arch_klp_init_object_loaded(struct klp_patch *patch, | |
697 | struct klp_object *obj) | |
698 | { | |
699 | } | |
700 | ||
b700e7f0 SJ |
701 | /* parts of the initialization that is done only when the object is loaded */ |
702 | static int klp_init_object_loaded(struct klp_patch *patch, | |
703 | struct klp_object *obj) | |
704 | { | |
705 | struct klp_func *func; | |
706 | int ret; | |
707 | ||
255e732c | 708 | module_disable_ro(patch->mod); |
425595a7 | 709 | ret = klp_write_object_relocations(patch->mod, obj); |
255e732c JY |
710 | if (ret) { |
711 | module_enable_ro(patch->mod, true); | |
425595a7 | 712 | return ret; |
255e732c JY |
713 | } |
714 | ||
715 | arch_klp_init_object_loaded(patch, obj); | |
716 | module_enable_ro(patch->mod, true); | |
b700e7f0 | 717 | |
8cdd043a | 718 | klp_for_each_func(obj, func) { |
b2b018ef CA |
719 | ret = klp_find_object_symbol(obj->name, func->old_name, |
720 | func->old_sympos, | |
721 | &func->old_addr); | |
b700e7f0 SJ |
722 | if (ret) |
723 | return ret; | |
f5e547f4 JP |
724 | |
725 | ret = kallsyms_lookup_size_offset(func->old_addr, | |
726 | &func->old_size, NULL); | |
727 | if (!ret) { | |
728 | pr_err("kallsyms size lookup failed for '%s'\n", | |
729 | func->old_name); | |
730 | return -ENOENT; | |
731 | } | |
732 | ||
733 | ret = kallsyms_lookup_size_offset((unsigned long)func->new_func, | |
734 | &func->new_size, NULL); | |
735 | if (!ret) { | |
736 | pr_err("kallsyms size lookup failed for '%s' replacement\n", | |
737 | func->old_name); | |
738 | return -ENOENT; | |
739 | } | |
b700e7f0 SJ |
740 | } |
741 | ||
742 | return 0; | |
743 | } | |
744 | ||
745 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
746 | { | |
747 | struct klp_func *func; | |
748 | int ret; | |
749 | const char *name; | |
750 | ||
751 | if (!obj->funcs) | |
752 | return -EINVAL; | |
753 | ||
0dade9f3 | 754 | obj->patched = false; |
8cb2c2dc | 755 | obj->mod = NULL; |
b700e7f0 SJ |
756 | |
757 | klp_find_object_module(obj); | |
758 | ||
759 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
cad706df MB |
760 | ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object, |
761 | &patch->kobj, "%s", name); | |
762 | if (ret) | |
763 | return ret; | |
b700e7f0 | 764 | |
8cdd043a | 765 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
766 | ret = klp_init_func(obj, func); |
767 | if (ret) | |
768 | goto free; | |
769 | } | |
770 | ||
771 | if (klp_is_object_loaded(obj)) { | |
772 | ret = klp_init_object_loaded(patch, obj); | |
773 | if (ret) | |
774 | goto free; | |
775 | } | |
776 | ||
777 | return 0; | |
778 | ||
779 | free: | |
780 | klp_free_funcs_limited(obj, func); | |
cad706df | 781 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
782 | return ret; |
783 | } | |
784 | ||
785 | static int klp_init_patch(struct klp_patch *patch) | |
786 | { | |
787 | struct klp_object *obj; | |
788 | int ret; | |
789 | ||
790 | if (!patch->objs) | |
791 | return -EINVAL; | |
792 | ||
793 | mutex_lock(&klp_mutex); | |
794 | ||
0dade9f3 | 795 | patch->enabled = false; |
3ec24776 | 796 | init_completion(&patch->finish); |
b700e7f0 SJ |
797 | |
798 | ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, | |
e0b561ee | 799 | klp_root_kobj, "%s", patch->mod->name); |
3ec24776 JP |
800 | if (ret) { |
801 | mutex_unlock(&klp_mutex); | |
802 | return ret; | |
803 | } | |
b700e7f0 | 804 | |
8cdd043a | 805 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
806 | ret = klp_init_object(patch, obj); |
807 | if (ret) | |
808 | goto free; | |
809 | } | |
810 | ||
99590ba5 | 811 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
812 | |
813 | mutex_unlock(&klp_mutex); | |
814 | ||
815 | return 0; | |
816 | ||
817 | free: | |
818 | klp_free_objects_limited(patch, obj); | |
3ec24776 | 819 | |
b700e7f0 | 820 | mutex_unlock(&klp_mutex); |
3ec24776 JP |
821 | |
822 | kobject_put(&patch->kobj); | |
823 | wait_for_completion(&patch->finish); | |
824 | ||
b700e7f0 SJ |
825 | return ret; |
826 | } | |
827 | ||
828 | /** | |
829 | * klp_unregister_patch() - unregisters a patch | |
830 | * @patch: Disabled patch to be unregistered | |
831 | * | |
832 | * Frees the data structures and removes the sysfs interface. | |
833 | * | |
834 | * Return: 0 on success, otherwise error | |
835 | */ | |
836 | int klp_unregister_patch(struct klp_patch *patch) | |
837 | { | |
3ec24776 | 838 | int ret; |
b700e7f0 SJ |
839 | |
840 | mutex_lock(&klp_mutex); | |
841 | ||
842 | if (!klp_is_patch_registered(patch)) { | |
843 | ret = -EINVAL; | |
3ec24776 | 844 | goto err; |
b700e7f0 SJ |
845 | } |
846 | ||
0dade9f3 | 847 | if (patch->enabled) { |
b700e7f0 | 848 | ret = -EBUSY; |
3ec24776 | 849 | goto err; |
b700e7f0 SJ |
850 | } |
851 | ||
852 | klp_free_patch(patch); | |
853 | ||
3ec24776 JP |
854 | mutex_unlock(&klp_mutex); |
855 | ||
856 | kobject_put(&patch->kobj); | |
857 | wait_for_completion(&patch->finish); | |
858 | ||
859 | return 0; | |
860 | err: | |
b700e7f0 SJ |
861 | mutex_unlock(&klp_mutex); |
862 | return ret; | |
863 | } | |
864 | EXPORT_SYMBOL_GPL(klp_unregister_patch); | |
865 | ||
866 | /** | |
867 | * klp_register_patch() - registers a patch | |
868 | * @patch: Patch to be registered | |
869 | * | |
870 | * Initializes the data structure associated with the patch and | |
871 | * creates the sysfs interface. | |
872 | * | |
3ec24776 JP |
873 | * There is no need to take the reference on the patch module here. It is done |
874 | * later when the patch is enabled. | |
875 | * | |
b700e7f0 SJ |
876 | * Return: 0 on success, otherwise error |
877 | */ | |
878 | int klp_register_patch(struct klp_patch *patch) | |
879 | { | |
b700e7f0 SJ |
880 | if (!patch || !patch->mod) |
881 | return -EINVAL; | |
882 | ||
425595a7 | 883 | if (!is_livepatch_module(patch->mod)) { |
77f8f39a | 884 | pr_err("module %s is not marked as a livepatch module\n", |
425595a7 JY |
885 | patch->mod->name); |
886 | return -EINVAL; | |
887 | } | |
888 | ||
b700e7f0 SJ |
889 | if (!klp_initialized()) |
890 | return -ENODEV; | |
891 | ||
d0807da7 | 892 | if (!klp_have_reliable_stack()) { |
d83a7cb3 JP |
893 | pr_err("This architecture doesn't have support for the livepatch consistency model.\n"); |
894 | return -ENOSYS; | |
895 | } | |
b700e7f0 | 896 | |
3ec24776 | 897 | return klp_init_patch(patch); |
b700e7f0 SJ |
898 | } |
899 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
900 | ||
ef8daf8e JL |
901 | /* |
902 | * Remove parts of patches that touch a given kernel module. The list of | |
903 | * patches processed might be limited. When limit is NULL, all patches | |
904 | * will be handled. | |
905 | */ | |
906 | static void klp_cleanup_module_patches_limited(struct module *mod, | |
907 | struct klp_patch *limit) | |
908 | { | |
909 | struct klp_patch *patch; | |
910 | struct klp_object *obj; | |
911 | ||
912 | list_for_each_entry(patch, &klp_patches, list) { | |
913 | if (patch == limit) | |
914 | break; | |
915 | ||
916 | klp_for_each_object(patch, obj) { | |
917 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
918 | continue; | |
919 | ||
920 | /* | |
921 | * Only unpatch the module if the patch is enabled or | |
922 | * is in transition. | |
923 | */ | |
924 | if (patch->enabled || patch == klp_transition_patch) { | |
fc41efc1 JK |
925 | |
926 | if (patch != klp_transition_patch) | |
927 | klp_pre_unpatch_callback(obj); | |
928 | ||
ef8daf8e JL |
929 | pr_notice("reverting patch '%s' on unloading module '%s'\n", |
930 | patch->mod->name, obj->mod->name); | |
931 | klp_unpatch_object(obj); | |
fc41efc1 JK |
932 | |
933 | klp_post_unpatch_callback(obj); | |
ef8daf8e JL |
934 | } |
935 | ||
936 | klp_free_object_loaded(obj); | |
937 | break; | |
938 | } | |
939 | } | |
940 | } | |
941 | ||
7e545d6e | 942 | int klp_module_coming(struct module *mod) |
b700e7f0 | 943 | { |
b700e7f0 | 944 | int ret; |
7e545d6e JY |
945 | struct klp_patch *patch; |
946 | struct klp_object *obj; | |
b700e7f0 | 947 | |
7e545d6e JY |
948 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
949 | return -EINVAL; | |
b700e7f0 | 950 | |
7e545d6e JY |
951 | mutex_lock(&klp_mutex); |
952 | /* | |
953 | * Each module has to know that klp_module_coming() | |
954 | * has been called. We never know what module will | |
955 | * get patched by a new patch. | |
956 | */ | |
957 | mod->klp_alive = true; | |
b700e7f0 | 958 | |
7e545d6e JY |
959 | list_for_each_entry(patch, &klp_patches, list) { |
960 | klp_for_each_object(patch, obj) { | |
961 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
962 | continue; | |
b700e7f0 | 963 | |
7e545d6e | 964 | obj->mod = mod; |
b700e7f0 | 965 | |
7e545d6e JY |
966 | ret = klp_init_object_loaded(patch, obj); |
967 | if (ret) { | |
968 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
969 | patch->mod->name, obj->mod->name, ret); | |
970 | goto err; | |
971 | } | |
b700e7f0 | 972 | |
d83a7cb3 JP |
973 | /* |
974 | * Only patch the module if the patch is enabled or is | |
975 | * in transition. | |
976 | */ | |
977 | if (!patch->enabled && patch != klp_transition_patch) | |
7e545d6e JY |
978 | break; |
979 | ||
980 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
981 | patch->mod->name, obj->mod->name); | |
982 | ||
93862e38 JL |
983 | ret = klp_pre_patch_callback(obj); |
984 | if (ret) { | |
985 | pr_warn("pre-patch callback failed for object '%s'\n", | |
986 | obj->name); | |
987 | goto err; | |
988 | } | |
989 | ||
0dade9f3 | 990 | ret = klp_patch_object(obj); |
7e545d6e JY |
991 | if (ret) { |
992 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
993 | patch->mod->name, obj->mod->name, ret); | |
93862e38 | 994 | |
5aaf1ab5 | 995 | klp_post_unpatch_callback(obj); |
7e545d6e JY |
996 | goto err; |
997 | } | |
998 | ||
93862e38 JL |
999 | if (patch != klp_transition_patch) |
1000 | klp_post_patch_callback(obj); | |
1001 | ||
7e545d6e JY |
1002 | break; |
1003 | } | |
1004 | } | |
b700e7f0 | 1005 | |
7e545d6e | 1006 | mutex_unlock(&klp_mutex); |
b700e7f0 | 1007 | |
7e545d6e | 1008 | return 0; |
b700e7f0 | 1009 | |
7e545d6e JY |
1010 | err: |
1011 | /* | |
1012 | * If a patch is unsuccessfully applied, return | |
1013 | * error to the module loader. | |
1014 | */ | |
1015 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
1016 | patch->mod->name, obj->mod->name, obj->mod->name); | |
1017 | mod->klp_alive = false; | |
ef8daf8e | 1018 | klp_cleanup_module_patches_limited(mod, patch); |
7e545d6e JY |
1019 | mutex_unlock(&klp_mutex); |
1020 | ||
1021 | return ret; | |
b700e7f0 SJ |
1022 | } |
1023 | ||
7e545d6e | 1024 | void klp_module_going(struct module *mod) |
b700e7f0 | 1025 | { |
7e545d6e JY |
1026 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1027 | mod->state != MODULE_STATE_COMING)) | |
1028 | return; | |
b700e7f0 SJ |
1029 | |
1030 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1031 | /* |
7e545d6e JY |
1032 | * Each module has to know that klp_module_going() |
1033 | * has been called. We never know what module will | |
1034 | * get patched by a new patch. | |
8cb2c2dc | 1035 | */ |
7e545d6e | 1036 | mod->klp_alive = false; |
8cb2c2dc | 1037 | |
ef8daf8e | 1038 | klp_cleanup_module_patches_limited(mod, NULL); |
b700e7f0 SJ |
1039 | |
1040 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1041 | } |
1042 | ||
26029d88 | 1043 | static int __init klp_init(void) |
b700e7f0 SJ |
1044 | { |
1045 | int ret; | |
1046 | ||
b9dfe0be JK |
1047 | ret = klp_check_compiler_support(); |
1048 | if (ret) { | |
1049 | pr_info("Your compiler is too old; turning off.\n"); | |
1050 | return -EINVAL; | |
1051 | } | |
1052 | ||
b700e7f0 | 1053 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1054 | if (!klp_root_kobj) |
1055 | return -ENOMEM; | |
b700e7f0 SJ |
1056 | |
1057 | return 0; | |
b700e7f0 SJ |
1058 | } |
1059 | ||
1060 | module_init(klp_init); |