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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 | ||
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. | |
369 | * | |
370 | * Note: For immediate (no consistency model) patches we don't allow | |
371 | * patch modules to unload since there is no safe/sane method to | |
372 | * determine if a thread is still running in the patched code contained | |
373 | * in the patch module once the ftrace registration is successful. | |
374 | */ | |
375 | if (!try_module_get(patch->mod)) | |
376 | return -ENODEV; | |
377 | ||
b700e7f0 SJ |
378 | pr_notice("enabling patch '%s'\n", patch->mod->name); |
379 | ||
d83a7cb3 JP |
380 | klp_init_transition(patch, KLP_PATCHED); |
381 | ||
382 | /* | |
383 | * Enforce the order of the func->transition writes in | |
384 | * klp_init_transition() and the ops->func_stack writes in | |
385 | * klp_patch_object(), so that klp_ftrace_handler() will see the | |
386 | * func->transition updates before the handler is registered and the | |
387 | * new funcs become visible to the handler. | |
388 | */ | |
389 | smp_wmb(); | |
390 | ||
8cdd043a | 391 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
392 | if (!klp_is_object_loaded(obj)) |
393 | continue; | |
394 | ||
93862e38 | 395 | ret = klp_pre_patch_callback(obj); |
d83a7cb3 | 396 | if (ret) { |
93862e38 JL |
397 | pr_warn("pre-patch callback failed for object '%s'\n", |
398 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
399 | goto err; | |
400 | } | |
d83a7cb3 | 401 | |
93862e38 JL |
402 | ret = klp_patch_object(obj); |
403 | if (ret) { | |
404 | pr_warn("failed to patch object '%s'\n", | |
405 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
406 | goto err; | |
d83a7cb3 | 407 | } |
b700e7f0 SJ |
408 | } |
409 | ||
d83a7cb3 JP |
410 | klp_start_transition(); |
411 | klp_try_complete_transition(); | |
0dade9f3 | 412 | patch->enabled = true; |
b700e7f0 SJ |
413 | |
414 | return 0; | |
93862e38 JL |
415 | err: |
416 | pr_warn("failed to enable patch '%s'\n", patch->mod->name); | |
417 | ||
418 | klp_cancel_transition(); | |
419 | return ret; | |
b700e7f0 SJ |
420 | } |
421 | ||
422 | /** | |
423 | * klp_enable_patch() - enables a registered patch | |
424 | * @patch: The registered, disabled patch to be enabled | |
425 | * | |
426 | * Performs the needed symbol lookups and code relocations, | |
427 | * then registers the patched functions with ftrace. | |
428 | * | |
429 | * Return: 0 on success, otherwise error | |
430 | */ | |
431 | int klp_enable_patch(struct klp_patch *patch) | |
432 | { | |
433 | int ret; | |
434 | ||
435 | mutex_lock(&klp_mutex); | |
436 | ||
437 | if (!klp_is_patch_registered(patch)) { | |
438 | ret = -EINVAL; | |
439 | goto err; | |
440 | } | |
441 | ||
442 | ret = __klp_enable_patch(patch); | |
443 | ||
444 | err: | |
445 | mutex_unlock(&klp_mutex); | |
446 | return ret; | |
447 | } | |
448 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
449 | ||
450 | /* | |
451 | * Sysfs Interface | |
452 | * | |
453 | * /sys/kernel/livepatch | |
454 | * /sys/kernel/livepatch/<patch> | |
455 | * /sys/kernel/livepatch/<patch>/enabled | |
d83a7cb3 | 456 | * /sys/kernel/livepatch/<patch>/transition |
43347d56 | 457 | * /sys/kernel/livepatch/<patch>/signal |
b700e7f0 | 458 | * /sys/kernel/livepatch/<patch>/<object> |
444f9e99 | 459 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 SJ |
460 | */ |
461 | ||
462 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
463 | const char *buf, size_t count) | |
464 | { | |
465 | struct klp_patch *patch; | |
466 | int ret; | |
68ae4b2b | 467 | bool enabled; |
b700e7f0 | 468 | |
68ae4b2b | 469 | ret = kstrtobool(buf, &enabled); |
b700e7f0 | 470 | if (ret) |
68ae4b2b | 471 | return ret; |
b700e7f0 SJ |
472 | |
473 | patch = container_of(kobj, struct klp_patch, kobj); | |
474 | ||
475 | mutex_lock(&klp_mutex); | |
476 | ||
3ec24776 JP |
477 | if (!klp_is_patch_registered(patch)) { |
478 | /* | |
479 | * Module with the patch could either disappear meanwhile or is | |
480 | * not properly initialized yet. | |
481 | */ | |
482 | ret = -EINVAL; | |
483 | goto err; | |
484 | } | |
485 | ||
68ae4b2b | 486 | if (patch->enabled == enabled) { |
b700e7f0 SJ |
487 | /* already in requested state */ |
488 | ret = -EINVAL; | |
489 | goto err; | |
490 | } | |
491 | ||
d83a7cb3 JP |
492 | if (patch == klp_transition_patch) { |
493 | klp_reverse_transition(); | |
494 | } else if (enabled) { | |
b700e7f0 SJ |
495 | ret = __klp_enable_patch(patch); |
496 | if (ret) | |
497 | goto err; | |
498 | } else { | |
499 | ret = __klp_disable_patch(patch); | |
500 | if (ret) | |
501 | goto err; | |
502 | } | |
503 | ||
504 | mutex_unlock(&klp_mutex); | |
505 | ||
506 | return count; | |
507 | ||
508 | err: | |
509 | mutex_unlock(&klp_mutex); | |
510 | return ret; | |
511 | } | |
512 | ||
513 | static ssize_t enabled_show(struct kobject *kobj, | |
514 | struct kobj_attribute *attr, char *buf) | |
515 | { | |
516 | struct klp_patch *patch; | |
517 | ||
518 | patch = container_of(kobj, struct klp_patch, kobj); | |
0dade9f3 | 519 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled); |
b700e7f0 SJ |
520 | } |
521 | ||
d83a7cb3 JP |
522 | static ssize_t transition_show(struct kobject *kobj, |
523 | struct kobj_attribute *attr, char *buf) | |
524 | { | |
525 | struct klp_patch *patch; | |
526 | ||
527 | patch = container_of(kobj, struct klp_patch, kobj); | |
528 | return snprintf(buf, PAGE_SIZE-1, "%d\n", | |
529 | patch == klp_transition_patch); | |
b700e7f0 SJ |
530 | } |
531 | ||
43347d56 MB |
532 | static ssize_t signal_store(struct kobject *kobj, struct kobj_attribute *attr, |
533 | const char *buf, size_t count) | |
534 | { | |
535 | struct klp_patch *patch; | |
536 | int ret; | |
537 | bool val; | |
538 | ||
539 | patch = container_of(kobj, struct klp_patch, kobj); | |
540 | ||
541 | /* | |
542 | * klp_mutex lock is not grabbed here intentionally. It is not really | |
543 | * needed. The race window is harmless and grabbing the lock would only | |
544 | * hold the action back. | |
545 | */ | |
546 | if (patch != klp_transition_patch) | |
547 | return -EINVAL; | |
548 | ||
549 | ret = kstrtobool(buf, &val); | |
550 | if (ret) | |
551 | return ret; | |
552 | ||
553 | if (val) | |
554 | klp_send_signals(); | |
555 | ||
556 | return count; | |
557 | } | |
558 | ||
b700e7f0 | 559 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); |
d83a7cb3 | 560 | static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); |
43347d56 | 561 | static struct kobj_attribute signal_kobj_attr = __ATTR_WO(signal); |
b700e7f0 SJ |
562 | static struct attribute *klp_patch_attrs[] = { |
563 | &enabled_kobj_attr.attr, | |
d83a7cb3 | 564 | &transition_kobj_attr.attr, |
43347d56 | 565 | &signal_kobj_attr.attr, |
b700e7f0 SJ |
566 | NULL |
567 | }; | |
568 | ||
569 | static void klp_kobj_release_patch(struct kobject *kobj) | |
570 | { | |
3ec24776 JP |
571 | struct klp_patch *patch; |
572 | ||
573 | patch = container_of(kobj, struct klp_patch, kobj); | |
574 | complete(&patch->finish); | |
b700e7f0 SJ |
575 | } |
576 | ||
577 | static struct kobj_type klp_ktype_patch = { | |
578 | .release = klp_kobj_release_patch, | |
579 | .sysfs_ops = &kobj_sysfs_ops, | |
580 | .default_attrs = klp_patch_attrs, | |
581 | }; | |
582 | ||
cad706df MB |
583 | static void klp_kobj_release_object(struct kobject *kobj) |
584 | { | |
585 | } | |
586 | ||
587 | static struct kobj_type klp_ktype_object = { | |
588 | .release = klp_kobj_release_object, | |
589 | .sysfs_ops = &kobj_sysfs_ops, | |
590 | }; | |
591 | ||
b700e7f0 SJ |
592 | static void klp_kobj_release_func(struct kobject *kobj) |
593 | { | |
b700e7f0 SJ |
594 | } |
595 | ||
596 | static struct kobj_type klp_ktype_func = { | |
597 | .release = klp_kobj_release_func, | |
598 | .sysfs_ops = &kobj_sysfs_ops, | |
599 | }; | |
600 | ||
601 | /* | |
602 | * Free all functions' kobjects in the array up to some limit. When limit is | |
603 | * NULL, all kobjects are freed. | |
604 | */ | |
605 | static void klp_free_funcs_limited(struct klp_object *obj, | |
606 | struct klp_func *limit) | |
607 | { | |
608 | struct klp_func *func; | |
609 | ||
610 | for (func = obj->funcs; func->old_name && func != limit; func++) | |
611 | kobject_put(&func->kobj); | |
612 | } | |
613 | ||
614 | /* Clean up when a patched object is unloaded */ | |
615 | static void klp_free_object_loaded(struct klp_object *obj) | |
616 | { | |
617 | struct klp_func *func; | |
618 | ||
619 | obj->mod = NULL; | |
620 | ||
8cdd043a | 621 | klp_for_each_func(obj, func) |
b700e7f0 SJ |
622 | func->old_addr = 0; |
623 | } | |
624 | ||
625 | /* | |
626 | * Free all objects' kobjects in the array up to some limit. When limit is | |
627 | * NULL, all kobjects are freed. | |
628 | */ | |
629 | static void klp_free_objects_limited(struct klp_patch *patch, | |
630 | struct klp_object *limit) | |
631 | { | |
632 | struct klp_object *obj; | |
633 | ||
634 | for (obj = patch->objs; obj->funcs && obj != limit; obj++) { | |
635 | klp_free_funcs_limited(obj, NULL); | |
cad706df | 636 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
637 | } |
638 | } | |
639 | ||
640 | static void klp_free_patch(struct klp_patch *patch) | |
641 | { | |
642 | klp_free_objects_limited(patch, NULL); | |
643 | if (!list_empty(&patch->list)) | |
644 | list_del(&patch->list); | |
b700e7f0 SJ |
645 | } |
646 | ||
647 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) | |
648 | { | |
f09d9086 MB |
649 | if (!func->old_name || !func->new_func) |
650 | return -EINVAL; | |
651 | ||
3c33f5b9 | 652 | INIT_LIST_HEAD(&func->stack_node); |
0dade9f3 | 653 | func->patched = false; |
d83a7cb3 | 654 | func->transition = false; |
b700e7f0 | 655 | |
444f9e99 CA |
656 | /* The format for the sysfs directory is <function,sympos> where sympos |
657 | * is the nth occurrence of this symbol in kallsyms for the patched | |
658 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
659 | * since a unique symbol will be the first occurrence. | |
660 | */ | |
3c33f5b9 | 661 | return kobject_init_and_add(&func->kobj, &klp_ktype_func, |
444f9e99 CA |
662 | &obj->kobj, "%s,%lu", func->old_name, |
663 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
664 | } |
665 | ||
255e732c JY |
666 | /* Arches may override this to finish any remaining arch-specific tasks */ |
667 | void __weak arch_klp_init_object_loaded(struct klp_patch *patch, | |
668 | struct klp_object *obj) | |
669 | { | |
670 | } | |
671 | ||
b700e7f0 SJ |
672 | /* parts of the initialization that is done only when the object is loaded */ |
673 | static int klp_init_object_loaded(struct klp_patch *patch, | |
674 | struct klp_object *obj) | |
675 | { | |
676 | struct klp_func *func; | |
677 | int ret; | |
678 | ||
255e732c | 679 | module_disable_ro(patch->mod); |
425595a7 | 680 | ret = klp_write_object_relocations(patch->mod, obj); |
255e732c JY |
681 | if (ret) { |
682 | module_enable_ro(patch->mod, true); | |
425595a7 | 683 | return ret; |
255e732c JY |
684 | } |
685 | ||
686 | arch_klp_init_object_loaded(patch, obj); | |
687 | module_enable_ro(patch->mod, true); | |
b700e7f0 | 688 | |
8cdd043a | 689 | klp_for_each_func(obj, func) { |
b2b018ef CA |
690 | ret = klp_find_object_symbol(obj->name, func->old_name, |
691 | func->old_sympos, | |
692 | &func->old_addr); | |
b700e7f0 SJ |
693 | if (ret) |
694 | return ret; | |
f5e547f4 JP |
695 | |
696 | ret = kallsyms_lookup_size_offset(func->old_addr, | |
697 | &func->old_size, NULL); | |
698 | if (!ret) { | |
699 | pr_err("kallsyms size lookup failed for '%s'\n", | |
700 | func->old_name); | |
701 | return -ENOENT; | |
702 | } | |
703 | ||
704 | ret = kallsyms_lookup_size_offset((unsigned long)func->new_func, | |
705 | &func->new_size, NULL); | |
706 | if (!ret) { | |
707 | pr_err("kallsyms size lookup failed for '%s' replacement\n", | |
708 | func->old_name); | |
709 | return -ENOENT; | |
710 | } | |
b700e7f0 SJ |
711 | } |
712 | ||
713 | return 0; | |
714 | } | |
715 | ||
716 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
717 | { | |
718 | struct klp_func *func; | |
719 | int ret; | |
720 | const char *name; | |
721 | ||
722 | if (!obj->funcs) | |
723 | return -EINVAL; | |
724 | ||
0dade9f3 | 725 | obj->patched = false; |
8cb2c2dc | 726 | obj->mod = NULL; |
b700e7f0 SJ |
727 | |
728 | klp_find_object_module(obj); | |
729 | ||
730 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
cad706df MB |
731 | ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object, |
732 | &patch->kobj, "%s", name); | |
733 | if (ret) | |
734 | return ret; | |
b700e7f0 | 735 | |
8cdd043a | 736 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
737 | ret = klp_init_func(obj, func); |
738 | if (ret) | |
739 | goto free; | |
740 | } | |
741 | ||
742 | if (klp_is_object_loaded(obj)) { | |
743 | ret = klp_init_object_loaded(patch, obj); | |
744 | if (ret) | |
745 | goto free; | |
746 | } | |
747 | ||
748 | return 0; | |
749 | ||
750 | free: | |
751 | klp_free_funcs_limited(obj, func); | |
cad706df | 752 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
753 | return ret; |
754 | } | |
755 | ||
756 | static int klp_init_patch(struct klp_patch *patch) | |
757 | { | |
758 | struct klp_object *obj; | |
759 | int ret; | |
760 | ||
761 | if (!patch->objs) | |
762 | return -EINVAL; | |
763 | ||
764 | mutex_lock(&klp_mutex); | |
765 | ||
0dade9f3 | 766 | patch->enabled = false; |
3ec24776 | 767 | init_completion(&patch->finish); |
b700e7f0 SJ |
768 | |
769 | ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch, | |
e0b561ee | 770 | klp_root_kobj, "%s", patch->mod->name); |
3ec24776 JP |
771 | if (ret) { |
772 | mutex_unlock(&klp_mutex); | |
773 | return ret; | |
774 | } | |
b700e7f0 | 775 | |
8cdd043a | 776 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
777 | ret = klp_init_object(patch, obj); |
778 | if (ret) | |
779 | goto free; | |
780 | } | |
781 | ||
99590ba5 | 782 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 SJ |
783 | |
784 | mutex_unlock(&klp_mutex); | |
785 | ||
786 | return 0; | |
787 | ||
788 | free: | |
789 | klp_free_objects_limited(patch, obj); | |
3ec24776 | 790 | |
b700e7f0 | 791 | mutex_unlock(&klp_mutex); |
3ec24776 JP |
792 | |
793 | kobject_put(&patch->kobj); | |
794 | wait_for_completion(&patch->finish); | |
795 | ||
b700e7f0 SJ |
796 | return ret; |
797 | } | |
798 | ||
799 | /** | |
800 | * klp_unregister_patch() - unregisters a patch | |
801 | * @patch: Disabled patch to be unregistered | |
802 | * | |
803 | * Frees the data structures and removes the sysfs interface. | |
804 | * | |
805 | * Return: 0 on success, otherwise error | |
806 | */ | |
807 | int klp_unregister_patch(struct klp_patch *patch) | |
808 | { | |
3ec24776 | 809 | int ret; |
b700e7f0 SJ |
810 | |
811 | mutex_lock(&klp_mutex); | |
812 | ||
813 | if (!klp_is_patch_registered(patch)) { | |
814 | ret = -EINVAL; | |
3ec24776 | 815 | goto err; |
b700e7f0 SJ |
816 | } |
817 | ||
0dade9f3 | 818 | if (patch->enabled) { |
b700e7f0 | 819 | ret = -EBUSY; |
3ec24776 | 820 | goto err; |
b700e7f0 SJ |
821 | } |
822 | ||
823 | klp_free_patch(patch); | |
824 | ||
3ec24776 JP |
825 | mutex_unlock(&klp_mutex); |
826 | ||
827 | kobject_put(&patch->kobj); | |
828 | wait_for_completion(&patch->finish); | |
829 | ||
830 | return 0; | |
831 | err: | |
b700e7f0 SJ |
832 | mutex_unlock(&klp_mutex); |
833 | return ret; | |
834 | } | |
835 | EXPORT_SYMBOL_GPL(klp_unregister_patch); | |
836 | ||
837 | /** | |
838 | * klp_register_patch() - registers a patch | |
839 | * @patch: Patch to be registered | |
840 | * | |
841 | * Initializes the data structure associated with the patch and | |
842 | * creates the sysfs interface. | |
843 | * | |
3ec24776 JP |
844 | * There is no need to take the reference on the patch module here. It is done |
845 | * later when the patch is enabled. | |
846 | * | |
b700e7f0 SJ |
847 | * Return: 0 on success, otherwise error |
848 | */ | |
849 | int klp_register_patch(struct klp_patch *patch) | |
850 | { | |
b700e7f0 SJ |
851 | if (!patch || !patch->mod) |
852 | return -EINVAL; | |
853 | ||
425595a7 | 854 | if (!is_livepatch_module(patch->mod)) { |
77f8f39a | 855 | pr_err("module %s is not marked as a livepatch module\n", |
425595a7 JY |
856 | patch->mod->name); |
857 | return -EINVAL; | |
858 | } | |
859 | ||
b700e7f0 SJ |
860 | if (!klp_initialized()) |
861 | return -ENODEV; | |
862 | ||
b700e7f0 | 863 | /* |
d83a7cb3 JP |
864 | * Architectures without reliable stack traces have to set |
865 | * patch->immediate because there's currently no way to patch kthreads | |
866 | * with the consistency model. | |
b700e7f0 | 867 | */ |
d83a7cb3 JP |
868 | if (!klp_have_reliable_stack() && !patch->immediate) { |
869 | pr_err("This architecture doesn't have support for the livepatch consistency model.\n"); | |
870 | return -ENOSYS; | |
871 | } | |
b700e7f0 | 872 | |
3ec24776 | 873 | return klp_init_patch(patch); |
b700e7f0 SJ |
874 | } |
875 | EXPORT_SYMBOL_GPL(klp_register_patch); | |
876 | ||
ef8daf8e JL |
877 | /* |
878 | * Remove parts of patches that touch a given kernel module. The list of | |
879 | * patches processed might be limited. When limit is NULL, all patches | |
880 | * will be handled. | |
881 | */ | |
882 | static void klp_cleanup_module_patches_limited(struct module *mod, | |
883 | struct klp_patch *limit) | |
884 | { | |
885 | struct klp_patch *patch; | |
886 | struct klp_object *obj; | |
887 | ||
888 | list_for_each_entry(patch, &klp_patches, list) { | |
889 | if (patch == limit) | |
890 | break; | |
891 | ||
892 | klp_for_each_object(patch, obj) { | |
893 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
894 | continue; | |
895 | ||
896 | /* | |
897 | * Only unpatch the module if the patch is enabled or | |
898 | * is in transition. | |
899 | */ | |
900 | if (patch->enabled || patch == klp_transition_patch) { | |
fc41efc1 JK |
901 | |
902 | if (patch != klp_transition_patch) | |
903 | klp_pre_unpatch_callback(obj); | |
904 | ||
ef8daf8e JL |
905 | pr_notice("reverting patch '%s' on unloading module '%s'\n", |
906 | patch->mod->name, obj->mod->name); | |
907 | klp_unpatch_object(obj); | |
fc41efc1 JK |
908 | |
909 | klp_post_unpatch_callback(obj); | |
ef8daf8e JL |
910 | } |
911 | ||
912 | klp_free_object_loaded(obj); | |
913 | break; | |
914 | } | |
915 | } | |
916 | } | |
917 | ||
7e545d6e | 918 | int klp_module_coming(struct module *mod) |
b700e7f0 | 919 | { |
b700e7f0 | 920 | int ret; |
7e545d6e JY |
921 | struct klp_patch *patch; |
922 | struct klp_object *obj; | |
b700e7f0 | 923 | |
7e545d6e JY |
924 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
925 | return -EINVAL; | |
b700e7f0 | 926 | |
7e545d6e JY |
927 | mutex_lock(&klp_mutex); |
928 | /* | |
929 | * Each module has to know that klp_module_coming() | |
930 | * has been called. We never know what module will | |
931 | * get patched by a new patch. | |
932 | */ | |
933 | mod->klp_alive = true; | |
b700e7f0 | 934 | |
7e545d6e JY |
935 | list_for_each_entry(patch, &klp_patches, list) { |
936 | klp_for_each_object(patch, obj) { | |
937 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
938 | continue; | |
b700e7f0 | 939 | |
7e545d6e | 940 | obj->mod = mod; |
b700e7f0 | 941 | |
7e545d6e JY |
942 | ret = klp_init_object_loaded(patch, obj); |
943 | if (ret) { | |
944 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
945 | patch->mod->name, obj->mod->name, ret); | |
946 | goto err; | |
947 | } | |
b700e7f0 | 948 | |
d83a7cb3 JP |
949 | /* |
950 | * Only patch the module if the patch is enabled or is | |
951 | * in transition. | |
952 | */ | |
953 | if (!patch->enabled && patch != klp_transition_patch) | |
7e545d6e JY |
954 | break; |
955 | ||
956 | pr_notice("applying patch '%s' to loading module '%s'\n", | |
957 | patch->mod->name, obj->mod->name); | |
958 | ||
93862e38 JL |
959 | ret = klp_pre_patch_callback(obj); |
960 | if (ret) { | |
961 | pr_warn("pre-patch callback failed for object '%s'\n", | |
962 | obj->name); | |
963 | goto err; | |
964 | } | |
965 | ||
0dade9f3 | 966 | ret = klp_patch_object(obj); |
7e545d6e JY |
967 | if (ret) { |
968 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
969 | patch->mod->name, obj->mod->name, ret); | |
93862e38 | 970 | |
5aaf1ab5 | 971 | klp_post_unpatch_callback(obj); |
7e545d6e JY |
972 | goto err; |
973 | } | |
974 | ||
93862e38 JL |
975 | if (patch != klp_transition_patch) |
976 | klp_post_patch_callback(obj); | |
977 | ||
7e545d6e JY |
978 | break; |
979 | } | |
980 | } | |
b700e7f0 | 981 | |
7e545d6e | 982 | mutex_unlock(&klp_mutex); |
b700e7f0 | 983 | |
7e545d6e | 984 | return 0; |
b700e7f0 | 985 | |
7e545d6e JY |
986 | err: |
987 | /* | |
988 | * If a patch is unsuccessfully applied, return | |
989 | * error to the module loader. | |
990 | */ | |
991 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
992 | patch->mod->name, obj->mod->name, obj->mod->name); | |
993 | mod->klp_alive = false; | |
ef8daf8e | 994 | klp_cleanup_module_patches_limited(mod, patch); |
7e545d6e JY |
995 | mutex_unlock(&klp_mutex); |
996 | ||
997 | return ret; | |
b700e7f0 SJ |
998 | } |
999 | ||
7e545d6e | 1000 | void klp_module_going(struct module *mod) |
b700e7f0 | 1001 | { |
7e545d6e JY |
1002 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1003 | mod->state != MODULE_STATE_COMING)) | |
1004 | return; | |
b700e7f0 SJ |
1005 | |
1006 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1007 | /* |
7e545d6e JY |
1008 | * Each module has to know that klp_module_going() |
1009 | * has been called. We never know what module will | |
1010 | * get patched by a new patch. | |
8cb2c2dc | 1011 | */ |
7e545d6e | 1012 | mod->klp_alive = false; |
8cb2c2dc | 1013 | |
ef8daf8e | 1014 | klp_cleanup_module_patches_limited(mod, NULL); |
b700e7f0 SJ |
1015 | |
1016 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1017 | } |
1018 | ||
26029d88 | 1019 | static int __init klp_init(void) |
b700e7f0 SJ |
1020 | { |
1021 | int ret; | |
1022 | ||
b9dfe0be JK |
1023 | ret = klp_check_compiler_support(); |
1024 | if (ret) { | |
1025 | pr_info("Your compiler is too old; turning off.\n"); | |
1026 | return -EINVAL; | |
1027 | } | |
1028 | ||
b700e7f0 | 1029 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1030 | if (!klp_root_kobj) |
1031 | return -ENOMEM; | |
b700e7f0 SJ |
1032 | |
1033 | return 0; | |
b700e7f0 SJ |
1034 | } |
1035 | ||
1036 | module_init(klp_init); |