Commit | Line | Data |
---|---|---|
1ccea77e | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
b700e7f0 SJ |
2 | /* |
3 | * core.c - Kernel Live Patching Core | |
4 | * | |
5 | * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> | |
6 | * Copyright (C) 2014 SUSE | |
b700e7f0 SJ |
7 | */ |
8 | ||
9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/mutex.h> | |
14 | #include <linux/slab.h> | |
b700e7f0 SJ |
15 | #include <linux/list.h> |
16 | #include <linux/kallsyms.h> | |
17 | #include <linux/livepatch.h> | |
425595a7 JY |
18 | #include <linux/elf.h> |
19 | #include <linux/moduleloader.h> | |
3ec24776 | 20 | #include <linux/completion.h> |
9f255b63 | 21 | #include <linux/memory.h> |
a0060505 | 22 | #include <linux/rcupdate.h> |
b56b36ee | 23 | #include <asm/cacheflush.h> |
10517429 | 24 | #include "core.h" |
c349cdca | 25 | #include "patch.h" |
92c9abf5 | 26 | #include "state.h" |
d83a7cb3 | 27 | #include "transition.h" |
b700e7f0 | 28 | |
3c33f5b9 | 29 | /* |
d83a7cb3 JP |
30 | * klp_mutex is a coarse lock which serializes access to klp data. All |
31 | * accesses to klp-related variables and structures must have mutex protection, | |
32 | * except within the following functions which carefully avoid the need for it: | |
33 | * | |
34 | * - klp_ftrace_handler() | |
35 | * - klp_update_patch_state() | |
3c33f5b9 | 36 | */ |
d83a7cb3 | 37 | DEFINE_MUTEX(klp_mutex); |
3c33f5b9 | 38 | |
958ef1e3 PM |
39 | /* |
40 | * Actively used patches: enabled or in transition. Note that replaced | |
41 | * or disabled patches are not listed even though the related kernel | |
42 | * module still can be loaded. | |
43 | */ | |
68007289 | 44 | LIST_HEAD(klp_patches); |
b700e7f0 SJ |
45 | |
46 | static struct kobject *klp_root_kobj; | |
47 | ||
48 | static bool klp_is_module(struct klp_object *obj) | |
49 | { | |
50 | return obj->name; | |
51 | } | |
52 | ||
b700e7f0 SJ |
53 | /* sets obj->mod if object is not vmlinux and module is found */ |
54 | static void klp_find_object_module(struct klp_object *obj) | |
55 | { | |
8cb2c2dc PM |
56 | struct module *mod; |
57 | ||
b700e7f0 SJ |
58 | if (!klp_is_module(obj)) |
59 | return; | |
60 | ||
a0060505 | 61 | rcu_read_lock_sched(); |
b700e7f0 | 62 | /* |
8cb2c2dc PM |
63 | * We do not want to block removal of patched modules and therefore |
64 | * we do not take a reference here. The patches are removed by | |
7e545d6e | 65 | * klp_module_going() instead. |
8cb2c2dc PM |
66 | */ |
67 | mod = find_module(obj->name); | |
68 | /* | |
7e545d6e JY |
69 | * Do not mess work of klp_module_coming() and klp_module_going(). |
70 | * Note that the patch might still be needed before klp_module_going() | |
8cb2c2dc PM |
71 | * is called. Module functions can be called even in the GOING state |
72 | * until mod->exit() finishes. This is especially important for | |
73 | * patches that modify semantic of the functions. | |
b700e7f0 | 74 | */ |
8cb2c2dc PM |
75 | if (mod && mod->klp_alive) |
76 | obj->mod = mod; | |
77 | ||
a0060505 | 78 | rcu_read_unlock_sched(); |
b700e7f0 SJ |
79 | } |
80 | ||
b700e7f0 SJ |
81 | static bool klp_initialized(void) |
82 | { | |
e76ff06a | 83 | return !!klp_root_kobj; |
b700e7f0 SJ |
84 | } |
85 | ||
e1452b60 JB |
86 | static struct klp_func *klp_find_func(struct klp_object *obj, |
87 | struct klp_func *old_func) | |
88 | { | |
89 | struct klp_func *func; | |
90 | ||
91 | klp_for_each_func(obj, func) { | |
92 | if ((strcmp(old_func->old_name, func->old_name) == 0) && | |
93 | (old_func->old_sympos == func->old_sympos)) { | |
94 | return func; | |
95 | } | |
96 | } | |
97 | ||
98 | return NULL; | |
99 | } | |
100 | ||
101 | static struct klp_object *klp_find_object(struct klp_patch *patch, | |
102 | struct klp_object *old_obj) | |
103 | { | |
104 | struct klp_object *obj; | |
105 | ||
106 | klp_for_each_object(patch, obj) { | |
107 | if (klp_is_module(old_obj)) { | |
108 | if (klp_is_module(obj) && | |
109 | strcmp(old_obj->name, obj->name) == 0) { | |
110 | return obj; | |
111 | } | |
112 | } else if (!klp_is_module(obj)) { | |
113 | return obj; | |
114 | } | |
115 | } | |
116 | ||
117 | return NULL; | |
118 | } | |
119 | ||
b700e7f0 SJ |
120 | struct klp_find_arg { |
121 | const char *objname; | |
122 | const char *name; | |
123 | unsigned long addr; | |
b700e7f0 | 124 | unsigned long count; |
b2b018ef | 125 | unsigned long pos; |
b700e7f0 SJ |
126 | }; |
127 | ||
128 | static int klp_find_callback(void *data, const char *name, | |
129 | struct module *mod, unsigned long addr) | |
130 | { | |
131 | struct klp_find_arg *args = data; | |
132 | ||
133 | if ((mod && !args->objname) || (!mod && args->objname)) | |
134 | return 0; | |
135 | ||
136 | if (strcmp(args->name, name)) | |
137 | return 0; | |
138 | ||
139 | if (args->objname && strcmp(args->objname, mod->name)) | |
140 | return 0; | |
141 | ||
b700e7f0 SJ |
142 | args->addr = addr; |
143 | args->count++; | |
144 | ||
b2b018ef CA |
145 | /* |
146 | * Finish the search when the symbol is found for the desired position | |
147 | * or the position is not defined for a non-unique symbol. | |
148 | */ | |
149 | if ((args->pos && (args->count == args->pos)) || | |
150 | (!args->pos && (args->count > 1))) | |
151 | return 1; | |
152 | ||
b700e7f0 SJ |
153 | return 0; |
154 | } | |
155 | ||
156 | static int klp_find_object_symbol(const char *objname, const char *name, | |
b2b018ef | 157 | unsigned long sympos, unsigned long *addr) |
b700e7f0 SJ |
158 | { |
159 | struct klp_find_arg args = { | |
160 | .objname = objname, | |
161 | .name = name, | |
162 | .addr = 0, | |
b2b018ef CA |
163 | .count = 0, |
164 | .pos = sympos, | |
b700e7f0 SJ |
165 | }; |
166 | ||
72f04b50 ZC |
167 | if (objname) |
168 | module_kallsyms_on_each_symbol(klp_find_callback, &args); | |
169 | else | |
170 | kallsyms_on_each_symbol(klp_find_callback, &args); | |
b700e7f0 | 171 | |
b2b018ef CA |
172 | /* |
173 | * Ensure an address was found. If sympos is 0, ensure symbol is unique; | |
174 | * otherwise ensure the symbol position count matches sympos. | |
175 | */ | |
176 | if (args.addr == 0) | |
b700e7f0 | 177 | pr_err("symbol '%s' not found in symbol table\n", name); |
b2b018ef | 178 | else if (args.count > 1 && sympos == 0) { |
f995b5f7 PM |
179 | pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n", |
180 | name, objname); | |
b2b018ef CA |
181 | } else if (sympos != args.count && sympos > 0) { |
182 | pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n", | |
183 | sympos, name, objname ? objname : "vmlinux"); | |
184 | } else { | |
b700e7f0 SJ |
185 | *addr = args.addr; |
186 | return 0; | |
187 | } | |
188 | ||
189 | *addr = 0; | |
190 | return -EINVAL; | |
191 | } | |
192 | ||
2f293651 | 193 | static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, |
ca376a93 JP |
194 | unsigned int symndx, Elf_Shdr *relasec, |
195 | const char *sec_objname) | |
b700e7f0 | 196 | { |
ca376a93 JP |
197 | int i, cnt, ret; |
198 | char sym_objname[MODULE_NAME_LEN]; | |
199 | char sym_name[KSYM_NAME_LEN]; | |
425595a7 JY |
200 | Elf_Rela *relas; |
201 | Elf_Sym *sym; | |
202 | unsigned long sympos, addr; | |
ca376a93 JP |
203 | bool sym_vmlinux; |
204 | bool sec_vmlinux = !strcmp(sec_objname, "vmlinux"); | |
b700e7f0 | 205 | |
b2b018ef | 206 | /* |
ca376a93 | 207 | * Since the field widths for sym_objname and sym_name in the sscanf() |
425595a7 JY |
208 | * call are hard-coded and correspond to MODULE_NAME_LEN and |
209 | * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN | |
210 | * and KSYM_NAME_LEN have the values we expect them to have. | |
211 | * | |
212 | * Because the value of MODULE_NAME_LEN can differ among architectures, | |
213 | * we use the smallest/strictest upper bound possible (56, based on | |
214 | * the current definition of MODULE_NAME_LEN) to prevent overflows. | |
b2b018ef | 215 | */ |
b8a94bfb | 216 | BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512); |
425595a7 JY |
217 | |
218 | relas = (Elf_Rela *) relasec->sh_addr; | |
219 | /* For each rela in this klp relocation section */ | |
220 | for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { | |
2f293651 | 221 | sym = (Elf_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info); |
425595a7 | 222 | if (sym->st_shndx != SHN_LIVEPATCH) { |
77f8f39a | 223 | pr_err("symbol %s is not marked as a livepatch symbol\n", |
425595a7 JY |
224 | strtab + sym->st_name); |
225 | return -EINVAL; | |
226 | } | |
227 | ||
ca376a93 | 228 | /* Format: .klp.sym.sym_objname.sym_name,sympos */ |
425595a7 | 229 | cnt = sscanf(strtab + sym->st_name, |
b8a94bfb | 230 | ".klp.sym.%55[^.].%511[^,],%lu", |
ca376a93 | 231 | sym_objname, sym_name, &sympos); |
425595a7 | 232 | if (cnt != 3) { |
77f8f39a | 233 | pr_err("symbol %s has an incorrectly formatted name\n", |
425595a7 JY |
234 | strtab + sym->st_name); |
235 | return -EINVAL; | |
236 | } | |
237 | ||
ca376a93 JP |
238 | sym_vmlinux = !strcmp(sym_objname, "vmlinux"); |
239 | ||
240 | /* | |
241 | * Prevent module-specific KLP rela sections from referencing | |
242 | * vmlinux symbols. This helps prevent ordering issues with | |
243 | * module special section initializations. Presumably such | |
244 | * symbols are exported and normal relas can be used instead. | |
245 | */ | |
246 | if (!sec_vmlinux && sym_vmlinux) { | |
247 | pr_err("invalid access to vmlinux symbol '%s' from module-specific livepatch relocation section", | |
248 | sym_name); | |
249 | return -EINVAL; | |
250 | } | |
251 | ||
425595a7 | 252 | /* klp_find_object_symbol() treats a NULL objname as vmlinux */ |
ca376a93 JP |
253 | ret = klp_find_object_symbol(sym_vmlinux ? NULL : sym_objname, |
254 | sym_name, sympos, &addr); | |
425595a7 JY |
255 | if (ret) |
256 | return ret; | |
257 | ||
258 | sym->st_value = addr; | |
259 | } | |
260 | ||
261 | return 0; | |
b700e7f0 SJ |
262 | } |
263 | ||
0c05e7bd SL |
264 | void __weak clear_relocate_add(Elf_Shdr *sechdrs, |
265 | const char *strtab, | |
266 | unsigned int symindex, | |
267 | unsigned int relsec, | |
268 | struct module *me) | |
269 | { | |
270 | } | |
271 | ||
7c8e2bdd JP |
272 | /* |
273 | * At a high-level, there are two types of klp relocation sections: those which | |
274 | * reference symbols which live in vmlinux; and those which reference symbols | |
275 | * which live in other modules. This function is called for both types: | |
276 | * | |
277 | * 1) When a klp module itself loads, the module code calls this function to | |
278 | * write vmlinux-specific klp relocations (.klp.rela.vmlinux.* sections). | |
279 | * These relocations are written to the klp module text to allow the patched | |
280 | * code/data to reference unexported vmlinux symbols. They're written as | |
281 | * early as possible to ensure that other module init code (.e.g., | |
282 | * jump_label_apply_nops) can access any unexported vmlinux symbols which | |
283 | * might be referenced by the klp module's special sections. | |
284 | * | |
285 | * 2) When a to-be-patched module loads -- or is already loaded when a | |
286 | * corresponding klp module loads -- klp code calls this function to write | |
287 | * module-specific klp relocations (.klp.rela.{module}.* sections). These | |
288 | * are written to the klp module text to allow the patched code/data to | |
289 | * reference symbols which live in the to-be-patched module or one of its | |
290 | * module dependencies. Exported symbols are supported, in addition to | |
291 | * unexported symbols, in order to enable late module patching, which allows | |
292 | * the to-be-patched module to be loaded and patched sometime *after* the | |
293 | * klp module is loaded. | |
294 | */ | |
0c05e7bd SL |
295 | static int klp_write_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, |
296 | const char *shstrtab, const char *strtab, | |
297 | unsigned int symndx, unsigned int secndx, | |
298 | const char *objname, bool apply) | |
b700e7f0 | 299 | { |
7c8e2bdd | 300 | int cnt, ret; |
425595a7 | 301 | char sec_objname[MODULE_NAME_LEN]; |
7c8e2bdd | 302 | Elf_Shdr *sec = sechdrs + secndx; |
b700e7f0 | 303 | |
7c8e2bdd JP |
304 | /* |
305 | * Format: .klp.rela.sec_objname.section_name | |
306 | * See comment in klp_resolve_symbols() for an explanation | |
307 | * of the selected field width value. | |
308 | */ | |
309 | cnt = sscanf(shstrtab + sec->sh_name, ".klp.rela.%55[^.]", | |
310 | sec_objname); | |
311 | if (cnt != 1) { | |
312 | pr_err("section %s has an incorrectly formatted name\n", | |
313 | shstrtab + sec->sh_name); | |
b700e7f0 | 314 | return -EINVAL; |
7c8e2bdd | 315 | } |
b700e7f0 | 316 | |
7c8e2bdd JP |
317 | if (strcmp(objname ? objname : "vmlinux", sec_objname)) |
318 | return 0; | |
064c89df | 319 | |
0c05e7bd SL |
320 | if (apply) { |
321 | ret = klp_resolve_symbols(sechdrs, strtab, symndx, | |
322 | sec, sec_objname); | |
323 | if (ret) | |
324 | return ret; | |
325 | ||
326 | return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); | |
327 | } | |
328 | ||
329 | clear_relocate_add(sechdrs, strtab, symndx, secndx, pmod); | |
330 | return 0; | |
331 | } | |
b700e7f0 | 332 | |
0c05e7bd SL |
333 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, |
334 | const char *shstrtab, const char *strtab, | |
335 | unsigned int symndx, unsigned int secndx, | |
336 | const char *objname) | |
337 | { | |
338 | return klp_write_section_relocs(pmod, sechdrs, shstrtab, strtab, symndx, | |
339 | secndx, objname, true); | |
b700e7f0 SJ |
340 | } |
341 | ||
b700e7f0 SJ |
342 | /* |
343 | * Sysfs Interface | |
344 | * | |
345 | * /sys/kernel/livepatch | |
346 | * /sys/kernel/livepatch/<patch> | |
347 | * /sys/kernel/livepatch/<patch>/enabled | |
d83a7cb3 | 348 | * /sys/kernel/livepatch/<patch>/transition |
c99a2be7 | 349 | * /sys/kernel/livepatch/<patch>/force |
b700e7f0 | 350 | * /sys/kernel/livepatch/<patch>/<object> |
bb26cfd9 | 351 | * /sys/kernel/livepatch/<patch>/<object>/patched |
444f9e99 | 352 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 | 353 | */ |
26c3e98e | 354 | static int __klp_disable_patch(struct klp_patch *patch); |
b700e7f0 SJ |
355 | |
356 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
357 | const char *buf, size_t count) | |
358 | { | |
359 | struct klp_patch *patch; | |
360 | int ret; | |
68ae4b2b | 361 | bool enabled; |
b700e7f0 | 362 | |
68ae4b2b | 363 | ret = kstrtobool(buf, &enabled); |
b700e7f0 | 364 | if (ret) |
68ae4b2b | 365 | return ret; |
b700e7f0 SJ |
366 | |
367 | patch = container_of(kobj, struct klp_patch, kobj); | |
368 | ||
369 | mutex_lock(&klp_mutex); | |
370 | ||
68ae4b2b | 371 | if (patch->enabled == enabled) { |
b700e7f0 SJ |
372 | /* already in requested state */ |
373 | ret = -EINVAL; | |
958ef1e3 | 374 | goto out; |
b700e7f0 SJ |
375 | } |
376 | ||
958ef1e3 PM |
377 | /* |
378 | * Allow to reverse a pending transition in both ways. It might be | |
379 | * necessary to complete the transition without forcing and breaking | |
380 | * the system integrity. | |
381 | * | |
382 | * Do not allow to re-enable a disabled patch. | |
383 | */ | |
384 | if (patch == klp_transition_patch) | |
d83a7cb3 | 385 | klp_reverse_transition(); |
958ef1e3 | 386 | else if (!enabled) |
b700e7f0 | 387 | ret = __klp_disable_patch(patch); |
958ef1e3 PM |
388 | else |
389 | ret = -EINVAL; | |
b700e7f0 | 390 | |
958ef1e3 | 391 | out: |
b700e7f0 SJ |
392 | mutex_unlock(&klp_mutex); |
393 | ||
958ef1e3 PM |
394 | if (ret) |
395 | return ret; | |
b700e7f0 | 396 | return count; |
b700e7f0 SJ |
397 | } |
398 | ||
399 | static ssize_t enabled_show(struct kobject *kobj, | |
400 | struct kobj_attribute *attr, char *buf) | |
401 | { | |
402 | struct klp_patch *patch; | |
403 | ||
404 | patch = container_of(kobj, struct klp_patch, kobj); | |
0dade9f3 | 405 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled); |
b700e7f0 SJ |
406 | } |
407 | ||
d83a7cb3 JP |
408 | static ssize_t transition_show(struct kobject *kobj, |
409 | struct kobj_attribute *attr, char *buf) | |
410 | { | |
411 | struct klp_patch *patch; | |
412 | ||
413 | patch = container_of(kobj, struct klp_patch, kobj); | |
414 | return snprintf(buf, PAGE_SIZE-1, "%d\n", | |
415 | patch == klp_transition_patch); | |
b700e7f0 SJ |
416 | } |
417 | ||
c99a2be7 MB |
418 | static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, |
419 | const char *buf, size_t count) | |
420 | { | |
421 | struct klp_patch *patch; | |
422 | int ret; | |
423 | bool val; | |
424 | ||
c99a2be7 MB |
425 | ret = kstrtobool(buf, &val); |
426 | if (ret) | |
427 | return ret; | |
428 | ||
8869016d MB |
429 | if (!val) |
430 | return count; | |
431 | ||
432 | mutex_lock(&klp_mutex); | |
433 | ||
434 | patch = container_of(kobj, struct klp_patch, kobj); | |
435 | if (patch != klp_transition_patch) { | |
436 | mutex_unlock(&klp_mutex); | |
437 | return -EINVAL; | |
438 | } | |
439 | ||
440 | klp_force_transition(); | |
441 | ||
442 | mutex_unlock(&klp_mutex); | |
c99a2be7 MB |
443 | |
444 | return count; | |
445 | } | |
446 | ||
b700e7f0 | 447 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); |
d83a7cb3 | 448 | static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); |
c99a2be7 | 449 | static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); |
b700e7f0 SJ |
450 | static struct attribute *klp_patch_attrs[] = { |
451 | &enabled_kobj_attr.attr, | |
d83a7cb3 | 452 | &transition_kobj_attr.attr, |
c99a2be7 | 453 | &force_kobj_attr.attr, |
b700e7f0 SJ |
454 | NULL |
455 | }; | |
70283454 | 456 | ATTRIBUTE_GROUPS(klp_patch); |
b700e7f0 | 457 | |
bb26cfd9 SL |
458 | static ssize_t patched_show(struct kobject *kobj, |
459 | struct kobj_attribute *attr, char *buf) | |
460 | { | |
461 | struct klp_object *obj; | |
462 | ||
463 | obj = container_of(kobj, struct klp_object, kobj); | |
464 | return sysfs_emit(buf, "%d\n", obj->patched); | |
465 | } | |
466 | ||
467 | static struct kobj_attribute patched_kobj_attr = __ATTR_RO(patched); | |
468 | static struct attribute *klp_object_attrs[] = { | |
469 | &patched_kobj_attr.attr, | |
470 | NULL, | |
471 | }; | |
472 | ATTRIBUTE_GROUPS(klp_object); | |
473 | ||
e1452b60 JB |
474 | static void klp_free_object_dynamic(struct klp_object *obj) |
475 | { | |
476 | kfree(obj->name); | |
477 | kfree(obj); | |
478 | } | |
479 | ||
f68d67cf PM |
480 | static void klp_init_func_early(struct klp_object *obj, |
481 | struct klp_func *func); | |
482 | static void klp_init_object_early(struct klp_patch *patch, | |
483 | struct klp_object *obj); | |
4d141ab3 | 484 | |
f68d67cf PM |
485 | static struct klp_object *klp_alloc_object_dynamic(const char *name, |
486 | struct klp_patch *patch) | |
e1452b60 JB |
487 | { |
488 | struct klp_object *obj; | |
489 | ||
490 | obj = kzalloc(sizeof(*obj), GFP_KERNEL); | |
491 | if (!obj) | |
492 | return NULL; | |
493 | ||
494 | if (name) { | |
495 | obj->name = kstrdup(name, GFP_KERNEL); | |
496 | if (!obj->name) { | |
497 | kfree(obj); | |
498 | return NULL; | |
499 | } | |
500 | } | |
501 | ||
f68d67cf | 502 | klp_init_object_early(patch, obj); |
e1452b60 JB |
503 | obj->dynamic = true; |
504 | ||
505 | return obj; | |
506 | } | |
507 | ||
508 | static void klp_free_func_nop(struct klp_func *func) | |
509 | { | |
510 | kfree(func->old_name); | |
511 | kfree(func); | |
512 | } | |
513 | ||
514 | static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func, | |
515 | struct klp_object *obj) | |
516 | { | |
517 | struct klp_func *func; | |
518 | ||
519 | func = kzalloc(sizeof(*func), GFP_KERNEL); | |
520 | if (!func) | |
521 | return NULL; | |
522 | ||
523 | if (old_func->old_name) { | |
524 | func->old_name = kstrdup(old_func->old_name, GFP_KERNEL); | |
525 | if (!func->old_name) { | |
526 | kfree(func); | |
527 | return NULL; | |
528 | } | |
529 | } | |
530 | ||
f68d67cf | 531 | klp_init_func_early(obj, func); |
e1452b60 JB |
532 | /* |
533 | * func->new_func is same as func->old_func. These addresses are | |
534 | * set when the object is loaded, see klp_init_object_loaded(). | |
535 | */ | |
536 | func->old_sympos = old_func->old_sympos; | |
537 | func->nop = true; | |
538 | ||
539 | return func; | |
540 | } | |
541 | ||
542 | static int klp_add_object_nops(struct klp_patch *patch, | |
543 | struct klp_object *old_obj) | |
544 | { | |
545 | struct klp_object *obj; | |
546 | struct klp_func *func, *old_func; | |
547 | ||
548 | obj = klp_find_object(patch, old_obj); | |
549 | ||
550 | if (!obj) { | |
f68d67cf | 551 | obj = klp_alloc_object_dynamic(old_obj->name, patch); |
e1452b60 JB |
552 | if (!obj) |
553 | return -ENOMEM; | |
e1452b60 JB |
554 | } |
555 | ||
556 | klp_for_each_func(old_obj, old_func) { | |
557 | func = klp_find_func(obj, old_func); | |
558 | if (func) | |
559 | continue; | |
560 | ||
561 | func = klp_alloc_func_nop(old_func, obj); | |
562 | if (!func) | |
563 | return -ENOMEM; | |
e1452b60 JB |
564 | } |
565 | ||
566 | return 0; | |
567 | } | |
568 | ||
569 | /* | |
570 | * Add 'nop' functions which simply return to the caller to run | |
571 | * the original function. The 'nop' functions are added to a | |
572 | * patch to facilitate a 'replace' mode. | |
573 | */ | |
574 | static int klp_add_nops(struct klp_patch *patch) | |
575 | { | |
576 | struct klp_patch *old_patch; | |
577 | struct klp_object *old_obj; | |
578 | ||
ecba29f4 | 579 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
580 | klp_for_each_object(old_patch, old_obj) { |
581 | int err; | |
582 | ||
583 | err = klp_add_object_nops(patch, old_obj); | |
584 | if (err) | |
585 | return err; | |
586 | } | |
587 | } | |
588 | ||
589 | return 0; | |
590 | } | |
591 | ||
b700e7f0 SJ |
592 | static void klp_kobj_release_patch(struct kobject *kobj) |
593 | { | |
3ec24776 JP |
594 | struct klp_patch *patch; |
595 | ||
596 | patch = container_of(kobj, struct klp_patch, kobj); | |
597 | complete(&patch->finish); | |
b700e7f0 SJ |
598 | } |
599 | ||
600 | static struct kobj_type klp_ktype_patch = { | |
601 | .release = klp_kobj_release_patch, | |
602 | .sysfs_ops = &kobj_sysfs_ops, | |
70283454 | 603 | .default_groups = klp_patch_groups, |
b700e7f0 SJ |
604 | }; |
605 | ||
cad706df MB |
606 | static void klp_kobj_release_object(struct kobject *kobj) |
607 | { | |
e1452b60 JB |
608 | struct klp_object *obj; |
609 | ||
610 | obj = container_of(kobj, struct klp_object, kobj); | |
611 | ||
612 | if (obj->dynamic) | |
613 | klp_free_object_dynamic(obj); | |
cad706df MB |
614 | } |
615 | ||
616 | static struct kobj_type klp_ktype_object = { | |
617 | .release = klp_kobj_release_object, | |
618 | .sysfs_ops = &kobj_sysfs_ops, | |
bb26cfd9 | 619 | .default_groups = klp_object_groups, |
cad706df MB |
620 | }; |
621 | ||
b700e7f0 SJ |
622 | static void klp_kobj_release_func(struct kobject *kobj) |
623 | { | |
e1452b60 JB |
624 | struct klp_func *func; |
625 | ||
626 | func = container_of(kobj, struct klp_func, kobj); | |
627 | ||
628 | if (func->nop) | |
629 | klp_free_func_nop(func); | |
b700e7f0 SJ |
630 | } |
631 | ||
632 | static struct kobj_type klp_ktype_func = { | |
633 | .release = klp_kobj_release_func, | |
634 | .sysfs_ops = &kobj_sysfs_ops, | |
635 | }; | |
636 | ||
d697bad5 | 637 | static void __klp_free_funcs(struct klp_object *obj, bool nops_only) |
b700e7f0 | 638 | { |
e1452b60 | 639 | struct klp_func *func, *tmp_func; |
b700e7f0 | 640 | |
e1452b60 | 641 | klp_for_each_func_safe(obj, func, tmp_func) { |
d697bad5 PM |
642 | if (nops_only && !func->nop) |
643 | continue; | |
644 | ||
645 | list_del(&func->node); | |
4d141ab3 | 646 | kobject_put(&func->kobj); |
0430f78b | 647 | } |
b700e7f0 SJ |
648 | } |
649 | ||
650 | /* Clean up when a patched object is unloaded */ | |
651 | static void klp_free_object_loaded(struct klp_object *obj) | |
652 | { | |
653 | struct klp_func *func; | |
654 | ||
655 | obj->mod = NULL; | |
656 | ||
e1452b60 | 657 | klp_for_each_func(obj, func) { |
19514910 | 658 | func->old_func = NULL; |
e1452b60 JB |
659 | |
660 | if (func->nop) | |
661 | func->new_func = NULL; | |
662 | } | |
b700e7f0 SJ |
663 | } |
664 | ||
d697bad5 | 665 | static void __klp_free_objects(struct klp_patch *patch, bool nops_only) |
b700e7f0 | 666 | { |
e1452b60 | 667 | struct klp_object *obj, *tmp_obj; |
b700e7f0 | 668 | |
e1452b60 | 669 | klp_for_each_object_safe(patch, obj, tmp_obj) { |
d697bad5 PM |
670 | __klp_free_funcs(obj, nops_only); |
671 | ||
672 | if (nops_only && !obj->dynamic) | |
673 | continue; | |
674 | ||
675 | list_del(&obj->node); | |
4d141ab3 | 676 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
677 | } |
678 | } | |
679 | ||
d697bad5 PM |
680 | static void klp_free_objects(struct klp_patch *patch) |
681 | { | |
682 | __klp_free_objects(patch, false); | |
683 | } | |
684 | ||
685 | static void klp_free_objects_dynamic(struct klp_patch *patch) | |
686 | { | |
687 | __klp_free_objects(patch, true); | |
688 | } | |
689 | ||
0430f78b PM |
690 | /* |
691 | * This function implements the free operations that can be called safely | |
692 | * under klp_mutex. | |
693 | * | |
694 | * The operation must be completed by calling klp_free_patch_finish() | |
695 | * outside klp_mutex. | |
696 | */ | |
7e35e4eb | 697 | static void klp_free_patch_start(struct klp_patch *patch) |
b700e7f0 | 698 | { |
b700e7f0 SJ |
699 | if (!list_empty(&patch->list)) |
700 | list_del(&patch->list); | |
0430f78b PM |
701 | |
702 | klp_free_objects(patch); | |
703 | } | |
704 | ||
705 | /* | |
706 | * This function implements the free part that must be called outside | |
707 | * klp_mutex. | |
708 | * | |
709 | * It must be called after klp_free_patch_start(). And it has to be | |
710 | * the last function accessing the livepatch structures when the patch | |
711 | * gets disabled. | |
712 | */ | |
713 | static void klp_free_patch_finish(struct klp_patch *patch) | |
714 | { | |
715 | /* | |
716 | * Avoid deadlock with enabled_store() sysfs callback by | |
717 | * calling this outside klp_mutex. It is safe because | |
718 | * this is called when the patch gets disabled and it | |
719 | * cannot get enabled again. | |
720 | */ | |
4d141ab3 PM |
721 | kobject_put(&patch->kobj); |
722 | wait_for_completion(&patch->finish); | |
958ef1e3 PM |
723 | |
724 | /* Put the module after the last access to struct klp_patch. */ | |
725 | if (!patch->forced) | |
726 | module_put(patch->mod); | |
727 | } | |
728 | ||
729 | /* | |
730 | * The livepatch might be freed from sysfs interface created by the patch. | |
731 | * This work allows to wait until the interface is destroyed in a separate | |
732 | * context. | |
733 | */ | |
734 | static void klp_free_patch_work_fn(struct work_struct *work) | |
735 | { | |
736 | struct klp_patch *patch = | |
737 | container_of(work, struct klp_patch, free_work); | |
738 | ||
739 | klp_free_patch_finish(patch); | |
b700e7f0 SJ |
740 | } |
741 | ||
7e35e4eb PM |
742 | void klp_free_patch_async(struct klp_patch *patch) |
743 | { | |
744 | klp_free_patch_start(patch); | |
745 | schedule_work(&patch->free_work); | |
746 | } | |
747 | ||
748 | void klp_free_replaced_patches_async(struct klp_patch *new_patch) | |
749 | { | |
750 | struct klp_patch *old_patch, *tmp_patch; | |
751 | ||
752 | klp_for_each_patch_safe(old_patch, tmp_patch) { | |
753 | if (old_patch == new_patch) | |
754 | return; | |
755 | klp_free_patch_async(old_patch); | |
756 | } | |
757 | } | |
758 | ||
b700e7f0 SJ |
759 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) |
760 | { | |
e1452b60 JB |
761 | if (!func->old_name) |
762 | return -EINVAL; | |
763 | ||
764 | /* | |
765 | * NOPs get the address later. The patched module must be loaded, | |
766 | * see klp_init_object_loaded(). | |
767 | */ | |
768 | if (!func->new_func && !func->nop) | |
f09d9086 MB |
769 | return -EINVAL; |
770 | ||
6e9df95b KB |
771 | if (strlen(func->old_name) >= KSYM_NAME_LEN) |
772 | return -EINVAL; | |
773 | ||
3c33f5b9 | 774 | INIT_LIST_HEAD(&func->stack_node); |
0dade9f3 | 775 | func->patched = false; |
d83a7cb3 | 776 | func->transition = false; |
b700e7f0 | 777 | |
444f9e99 CA |
778 | /* The format for the sysfs directory is <function,sympos> where sympos |
779 | * is the nth occurrence of this symbol in kallsyms for the patched | |
780 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
781 | * since a unique symbol will be the first occurrence. | |
782 | */ | |
4d141ab3 PM |
783 | return kobject_add(&func->kobj, &obj->kobj, "%s,%lu", |
784 | func->old_name, | |
785 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
786 | } |
787 | ||
0c05e7bd SL |
788 | static int klp_write_object_relocs(struct klp_patch *patch, |
789 | struct klp_object *obj, | |
790 | bool apply) | |
7c8e2bdd JP |
791 | { |
792 | int i, ret; | |
793 | struct klp_modinfo *info = patch->mod->klp_info; | |
794 | ||
795 | for (i = 1; i < info->hdr.e_shnum; i++) { | |
796 | Elf_Shdr *sec = info->sechdrs + i; | |
797 | ||
798 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
799 | continue; | |
800 | ||
0c05e7bd | 801 | ret = klp_write_section_relocs(patch->mod, info->sechdrs, |
7c8e2bdd JP |
802 | info->secstrings, |
803 | patch->mod->core_kallsyms.strtab, | |
0c05e7bd | 804 | info->symndx, i, obj->name, apply); |
7c8e2bdd JP |
805 | if (ret) |
806 | return ret; | |
807 | } | |
808 | ||
809 | return 0; | |
810 | } | |
811 | ||
0c05e7bd SL |
812 | static int klp_apply_object_relocs(struct klp_patch *patch, |
813 | struct klp_object *obj) | |
814 | { | |
815 | return klp_write_object_relocs(patch, obj, true); | |
816 | } | |
817 | ||
818 | static void klp_clear_object_relocs(struct klp_patch *patch, | |
819 | struct klp_object *obj) | |
820 | { | |
821 | klp_write_object_relocs(patch, obj, false); | |
822 | } | |
823 | ||
b700e7f0 SJ |
824 | /* parts of the initialization that is done only when the object is loaded */ |
825 | static int klp_init_object_loaded(struct klp_patch *patch, | |
826 | struct klp_object *obj) | |
827 | { | |
828 | struct klp_func *func; | |
829 | int ret; | |
830 | ||
7c8e2bdd JP |
831 | if (klp_is_module(obj)) { |
832 | /* | |
833 | * Only write module-specific relocations here | |
834 | * (.klp.rela.{module}.*). vmlinux-specific relocations were | |
835 | * written earlier during the initialization of the klp module | |
836 | * itself. | |
837 | */ | |
838 | ret = klp_apply_object_relocs(patch, obj); | |
1d05334d PZ |
839 | if (ret) |
840 | return ret; | |
841 | } | |
9f255b63 | 842 | |
8cdd043a | 843 | klp_for_each_func(obj, func) { |
b2b018ef CA |
844 | ret = klp_find_object_symbol(obj->name, func->old_name, |
845 | func->old_sympos, | |
19514910 | 846 | (unsigned long *)&func->old_func); |
b700e7f0 SJ |
847 | if (ret) |
848 | return ret; | |
f5e547f4 | 849 | |
19514910 | 850 | ret = kallsyms_lookup_size_offset((unsigned long)func->old_func, |
f5e547f4 JP |
851 | &func->old_size, NULL); |
852 | if (!ret) { | |
853 | pr_err("kallsyms size lookup failed for '%s'\n", | |
854 | func->old_name); | |
855 | return -ENOENT; | |
856 | } | |
857 | ||
e1452b60 JB |
858 | if (func->nop) |
859 | func->new_func = func->old_func; | |
860 | ||
f5e547f4 JP |
861 | ret = kallsyms_lookup_size_offset((unsigned long)func->new_func, |
862 | &func->new_size, NULL); | |
863 | if (!ret) { | |
864 | pr_err("kallsyms size lookup failed for '%s' replacement\n", | |
865 | func->old_name); | |
866 | return -ENOENT; | |
867 | } | |
b700e7f0 SJ |
868 | } |
869 | ||
870 | return 0; | |
871 | } | |
872 | ||
873 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
874 | { | |
875 | struct klp_func *func; | |
876 | int ret; | |
877 | const char *name; | |
878 | ||
6e9df95b KB |
879 | if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN) |
880 | return -EINVAL; | |
881 | ||
0dade9f3 | 882 | obj->patched = false; |
8cb2c2dc | 883 | obj->mod = NULL; |
b700e7f0 SJ |
884 | |
885 | klp_find_object_module(obj); | |
886 | ||
887 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
4d141ab3 | 888 | ret = kobject_add(&obj->kobj, &patch->kobj, "%s", name); |
cad706df MB |
889 | if (ret) |
890 | return ret; | |
b700e7f0 | 891 | |
8cdd043a | 892 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
893 | ret = klp_init_func(obj, func); |
894 | if (ret) | |
0430f78b | 895 | return ret; |
b700e7f0 SJ |
896 | } |
897 | ||
0430f78b | 898 | if (klp_is_object_loaded(obj)) |
b700e7f0 | 899 | ret = klp_init_object_loaded(patch, obj); |
b700e7f0 | 900 | |
b700e7f0 SJ |
901 | return ret; |
902 | } | |
903 | ||
f68d67cf PM |
904 | static void klp_init_func_early(struct klp_object *obj, |
905 | struct klp_func *func) | |
906 | { | |
907 | kobject_init(&func->kobj, &klp_ktype_func); | |
908 | list_add_tail(&func->node, &obj->func_list); | |
909 | } | |
910 | ||
911 | static void klp_init_object_early(struct klp_patch *patch, | |
912 | struct klp_object *obj) | |
913 | { | |
914 | INIT_LIST_HEAD(&obj->func_list); | |
915 | kobject_init(&obj->kobj, &klp_ktype_object); | |
916 | list_add_tail(&obj->node, &patch->obj_list); | |
917 | } | |
918 | ||
5ef3dd20 | 919 | static void klp_init_patch_early(struct klp_patch *patch) |
b700e7f0 SJ |
920 | { |
921 | struct klp_object *obj; | |
0430f78b | 922 | struct klp_func *func; |
b700e7f0 | 923 | |
0430f78b | 924 | INIT_LIST_HEAD(&patch->list); |
20e55025 | 925 | INIT_LIST_HEAD(&patch->obj_list); |
4d141ab3 | 926 | kobject_init(&patch->kobj, &klp_ktype_patch); |
0dade9f3 | 927 | patch->enabled = false; |
68007289 | 928 | patch->forced = false; |
958ef1e3 | 929 | INIT_WORK(&patch->free_work, klp_free_patch_work_fn); |
3ec24776 | 930 | init_completion(&patch->finish); |
b700e7f0 | 931 | |
20e55025 | 932 | klp_for_each_object_static(patch, obj) { |
f68d67cf | 933 | klp_init_object_early(patch, obj); |
0430f78b | 934 | |
20e55025 | 935 | klp_for_each_func_static(obj, func) { |
f68d67cf | 936 | klp_init_func_early(obj, func); |
20e55025 | 937 | } |
0430f78b | 938 | } |
0430f78b PM |
939 | } |
940 | ||
941 | static int klp_init_patch(struct klp_patch *patch) | |
942 | { | |
943 | struct klp_object *obj; | |
944 | int ret; | |
945 | ||
4d141ab3 | 946 | ret = kobject_add(&patch->kobj, klp_root_kobj, "%s", patch->mod->name); |
958ef1e3 | 947 | if (ret) |
3ec24776 | 948 | return ret; |
b700e7f0 | 949 | |
e1452b60 JB |
950 | if (patch->replace) { |
951 | ret = klp_add_nops(patch); | |
952 | if (ret) | |
953 | return ret; | |
954 | } | |
955 | ||
8cdd043a | 956 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
957 | ret = klp_init_object(patch, obj); |
958 | if (ret) | |
958ef1e3 | 959 | return ret; |
b700e7f0 SJ |
960 | } |
961 | ||
99590ba5 | 962 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 | 963 | |
3ec24776 | 964 | return 0; |
b700e7f0 | 965 | } |
b700e7f0 | 966 | |
26c3e98e PM |
967 | static int __klp_disable_patch(struct klp_patch *patch) |
968 | { | |
969 | struct klp_object *obj; | |
970 | ||
971 | if (WARN_ON(!patch->enabled)) | |
972 | return -EINVAL; | |
973 | ||
974 | if (klp_transition_patch) | |
975 | return -EBUSY; | |
976 | ||
26c3e98e PM |
977 | klp_init_transition(patch, KLP_UNPATCHED); |
978 | ||
979 | klp_for_each_object(patch, obj) | |
980 | if (obj->patched) | |
981 | klp_pre_unpatch_callback(obj); | |
982 | ||
983 | /* | |
984 | * Enforce the order of the func->transition writes in | |
985 | * klp_init_transition() and the TIF_PATCH_PENDING writes in | |
986 | * klp_start_transition(). In the rare case where klp_ftrace_handler() | |
987 | * is called shortly after klp_update_patch_state() switches the task, | |
988 | * this ensures the handler sees that func->transition is set. | |
989 | */ | |
990 | smp_wmb(); | |
991 | ||
992 | klp_start_transition(); | |
26c3e98e | 993 | patch->enabled = false; |
958ef1e3 | 994 | klp_try_complete_transition(); |
26c3e98e PM |
995 | |
996 | return 0; | |
997 | } | |
998 | ||
26c3e98e PM |
999 | static int __klp_enable_patch(struct klp_patch *patch) |
1000 | { | |
1001 | struct klp_object *obj; | |
1002 | int ret; | |
1003 | ||
1004 | if (klp_transition_patch) | |
1005 | return -EBUSY; | |
1006 | ||
1007 | if (WARN_ON(patch->enabled)) | |
1008 | return -EINVAL; | |
1009 | ||
26c3e98e PM |
1010 | pr_notice("enabling patch '%s'\n", patch->mod->name); |
1011 | ||
1012 | klp_init_transition(patch, KLP_PATCHED); | |
1013 | ||
1014 | /* | |
1015 | * Enforce the order of the func->transition writes in | |
1016 | * klp_init_transition() and the ops->func_stack writes in | |
1017 | * klp_patch_object(), so that klp_ftrace_handler() will see the | |
1018 | * func->transition updates before the handler is registered and the | |
1019 | * new funcs become visible to the handler. | |
1020 | */ | |
1021 | smp_wmb(); | |
1022 | ||
1023 | klp_for_each_object(patch, obj) { | |
1024 | if (!klp_is_object_loaded(obj)) | |
1025 | continue; | |
1026 | ||
1027 | ret = klp_pre_patch_callback(obj); | |
1028 | if (ret) { | |
1029 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1030 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
1031 | goto err; | |
1032 | } | |
1033 | ||
1034 | ret = klp_patch_object(obj); | |
1035 | if (ret) { | |
1036 | pr_warn("failed to patch object '%s'\n", | |
1037 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
1038 | goto err; | |
1039 | } | |
1040 | } | |
1041 | ||
1042 | klp_start_transition(); | |
26c3e98e | 1043 | patch->enabled = true; |
958ef1e3 | 1044 | klp_try_complete_transition(); |
26c3e98e PM |
1045 | |
1046 | return 0; | |
1047 | err: | |
1048 | pr_warn("failed to enable patch '%s'\n", patch->mod->name); | |
1049 | ||
1050 | klp_cancel_transition(); | |
1051 | return ret; | |
1052 | } | |
1053 | ||
1054 | /** | |
958ef1e3 PM |
1055 | * klp_enable_patch() - enable the livepatch |
1056 | * @patch: patch to be enabled | |
26c3e98e | 1057 | * |
958ef1e3 PM |
1058 | * Initializes the data structure associated with the patch, creates the sysfs |
1059 | * interface, performs the needed symbol lookups and code relocations, | |
1060 | * registers the patched functions with ftrace. | |
1061 | * | |
1062 | * This function is supposed to be called from the livepatch module_init() | |
1063 | * callback. | |
26c3e98e PM |
1064 | * |
1065 | * Return: 0 on success, otherwise error | |
1066 | */ | |
1067 | int klp_enable_patch(struct klp_patch *patch) | |
1068 | { | |
1069 | int ret; | |
5ef3dd20 | 1070 | struct klp_object *obj; |
26c3e98e | 1071 | |
5ef3dd20 | 1072 | if (!patch || !patch->mod || !patch->objs) |
958ef1e3 PM |
1073 | return -EINVAL; |
1074 | ||
5ef3dd20 DV |
1075 | klp_for_each_object_static(patch, obj) { |
1076 | if (!obj->funcs) | |
1077 | return -EINVAL; | |
1078 | } | |
1079 | ||
1080 | ||
958ef1e3 PM |
1081 | if (!is_livepatch_module(patch->mod)) { |
1082 | pr_err("module %s is not marked as a livepatch module\n", | |
1083 | patch->mod->name); | |
1084 | return -EINVAL; | |
1085 | } | |
1086 | ||
1087 | if (!klp_initialized()) | |
1088 | return -ENODEV; | |
1089 | ||
1090 | if (!klp_have_reliable_stack()) { | |
31adf230 PM |
1091 | pr_warn("This architecture doesn't have support for the livepatch consistency model.\n"); |
1092 | pr_warn("The livepatch transition may never complete.\n"); | |
958ef1e3 PM |
1093 | } |
1094 | ||
26c3e98e PM |
1095 | mutex_lock(&klp_mutex); |
1096 | ||
92c9abf5 PM |
1097 | if (!klp_is_patch_compatible(patch)) { |
1098 | pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n", | |
1099 | patch->mod->name); | |
1100 | mutex_unlock(&klp_mutex); | |
1101 | return -EINVAL; | |
1102 | } | |
1103 | ||
50a0f3f5 YY |
1104 | if (!try_module_get(patch->mod)) { |
1105 | mutex_unlock(&klp_mutex); | |
5ef3dd20 | 1106 | return -ENODEV; |
50a0f3f5 | 1107 | } |
5ef3dd20 DV |
1108 | |
1109 | klp_init_patch_early(patch); | |
26c3e98e | 1110 | |
958ef1e3 PM |
1111 | ret = klp_init_patch(patch); |
1112 | if (ret) | |
1113 | goto err; | |
1114 | ||
26c3e98e | 1115 | ret = __klp_enable_patch(patch); |
958ef1e3 PM |
1116 | if (ret) |
1117 | goto err; | |
1118 | ||
1119 | mutex_unlock(&klp_mutex); | |
1120 | ||
1121 | return 0; | |
26c3e98e PM |
1122 | |
1123 | err: | |
958ef1e3 PM |
1124 | klp_free_patch_start(patch); |
1125 | ||
26c3e98e | 1126 | mutex_unlock(&klp_mutex); |
958ef1e3 PM |
1127 | |
1128 | klp_free_patch_finish(patch); | |
1129 | ||
26c3e98e PM |
1130 | return ret; |
1131 | } | |
1132 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
1133 | ||
e1452b60 | 1134 | /* |
7e35e4eb | 1135 | * This function unpatches objects from the replaced livepatches. |
e1452b60 JB |
1136 | * |
1137 | * We could be pretty aggressive here. It is called in the situation where | |
7e35e4eb PM |
1138 | * these structures are no longer accessed from the ftrace handler. |
1139 | * All functions are redirected by the klp_transition_patch. They | |
1140 | * use either a new code or they are in the original code because | |
1141 | * of the special nop function patches. | |
e1452b60 JB |
1142 | * |
1143 | * The only exception is when the transition was forced. In this case, | |
1144 | * klp_ftrace_handler() might still see the replaced patch on the stack. | |
1145 | * Fortunately, it is carefully designed to work with removed functions | |
1146 | * thanks to RCU. We only have to keep the patches on the system. Also | |
1147 | * this is handled transparently by patch->module_put. | |
1148 | */ | |
7e35e4eb | 1149 | void klp_unpatch_replaced_patches(struct klp_patch *new_patch) |
e1452b60 | 1150 | { |
7e35e4eb | 1151 | struct klp_patch *old_patch; |
e1452b60 | 1152 | |
7e35e4eb | 1153 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
1154 | if (old_patch == new_patch) |
1155 | return; | |
1156 | ||
1157 | old_patch->enabled = false; | |
1158 | klp_unpatch_objects(old_patch); | |
e1452b60 JB |
1159 | } |
1160 | } | |
1161 | ||
d697bad5 PM |
1162 | /* |
1163 | * This function removes the dynamically allocated 'nop' functions. | |
1164 | * | |
1165 | * We could be pretty aggressive. NOPs do not change the existing | |
1166 | * behavior except for adding unnecessary delay by the ftrace handler. | |
1167 | * | |
1168 | * It is safe even when the transition was forced. The ftrace handler | |
1169 | * will see a valid ops->func_stack entry thanks to RCU. | |
1170 | * | |
1171 | * We could even free the NOPs structures. They must be the last entry | |
1172 | * in ops->func_stack. Therefore unregister_ftrace_function() is called. | |
1173 | * It does the same as klp_synchronize_transition() to make sure that | |
1174 | * nobody is inside the ftrace handler once the operation finishes. | |
1175 | * | |
1176 | * IMPORTANT: It must be called right after removing the replaced patches! | |
1177 | */ | |
1178 | void klp_discard_nops(struct klp_patch *new_patch) | |
1179 | { | |
1180 | klp_unpatch_objects_dynamic(klp_transition_patch); | |
1181 | klp_free_objects_dynamic(klp_transition_patch); | |
1182 | } | |
1183 | ||
ef8daf8e JL |
1184 | /* |
1185 | * Remove parts of patches that touch a given kernel module. The list of | |
1186 | * patches processed might be limited. When limit is NULL, all patches | |
1187 | * will be handled. | |
1188 | */ | |
1189 | static void klp_cleanup_module_patches_limited(struct module *mod, | |
1190 | struct klp_patch *limit) | |
1191 | { | |
1192 | struct klp_patch *patch; | |
1193 | struct klp_object *obj; | |
1194 | ||
ecba29f4 | 1195 | klp_for_each_patch(patch) { |
ef8daf8e JL |
1196 | if (patch == limit) |
1197 | break; | |
1198 | ||
1199 | klp_for_each_object(patch, obj) { | |
1200 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1201 | continue; | |
1202 | ||
a087cdd4 PM |
1203 | if (patch != klp_transition_patch) |
1204 | klp_pre_unpatch_callback(obj); | |
fc41efc1 | 1205 | |
a087cdd4 PM |
1206 | pr_notice("reverting patch '%s' on unloading module '%s'\n", |
1207 | patch->mod->name, obj->mod->name); | |
1208 | klp_unpatch_object(obj); | |
fc41efc1 | 1209 | |
a087cdd4 | 1210 | klp_post_unpatch_callback(obj); |
0c05e7bd | 1211 | klp_clear_object_relocs(patch, obj); |
ef8daf8e JL |
1212 | klp_free_object_loaded(obj); |
1213 | break; | |
1214 | } | |
1215 | } | |
1216 | } | |
1217 | ||
7e545d6e | 1218 | int klp_module_coming(struct module *mod) |
b700e7f0 | 1219 | { |
b700e7f0 | 1220 | int ret; |
7e545d6e JY |
1221 | struct klp_patch *patch; |
1222 | struct klp_object *obj; | |
b700e7f0 | 1223 | |
7e545d6e JY |
1224 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
1225 | return -EINVAL; | |
b700e7f0 | 1226 | |
dcf550e5 | 1227 | if (!strcmp(mod->name, "vmlinux")) { |
66d8529d | 1228 | pr_err("vmlinux.ko: invalid module name\n"); |
dcf550e5 JP |
1229 | return -EINVAL; |
1230 | } | |
1231 | ||
7e545d6e JY |
1232 | mutex_lock(&klp_mutex); |
1233 | /* | |
1234 | * Each module has to know that klp_module_coming() | |
1235 | * has been called. We never know what module will | |
1236 | * get patched by a new patch. | |
1237 | */ | |
1238 | mod->klp_alive = true; | |
b700e7f0 | 1239 | |
ecba29f4 | 1240 | klp_for_each_patch(patch) { |
7e545d6e JY |
1241 | klp_for_each_object(patch, obj) { |
1242 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1243 | continue; | |
b700e7f0 | 1244 | |
7e545d6e | 1245 | obj->mod = mod; |
b700e7f0 | 1246 | |
7e545d6e JY |
1247 | ret = klp_init_object_loaded(patch, obj); |
1248 | if (ret) { | |
1249 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
1250 | patch->mod->name, obj->mod->name, ret); | |
1251 | goto err; | |
1252 | } | |
b700e7f0 | 1253 | |
7e545d6e JY |
1254 | pr_notice("applying patch '%s' to loading module '%s'\n", |
1255 | patch->mod->name, obj->mod->name); | |
1256 | ||
93862e38 JL |
1257 | ret = klp_pre_patch_callback(obj); |
1258 | if (ret) { | |
1259 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1260 | obj->name); | |
1261 | goto err; | |
1262 | } | |
1263 | ||
0dade9f3 | 1264 | ret = klp_patch_object(obj); |
7e545d6e JY |
1265 | if (ret) { |
1266 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
1267 | patch->mod->name, obj->mod->name, ret); | |
93862e38 | 1268 | |
5aaf1ab5 | 1269 | klp_post_unpatch_callback(obj); |
7e545d6e JY |
1270 | goto err; |
1271 | } | |
1272 | ||
93862e38 JL |
1273 | if (patch != klp_transition_patch) |
1274 | klp_post_patch_callback(obj); | |
1275 | ||
7e545d6e JY |
1276 | break; |
1277 | } | |
1278 | } | |
b700e7f0 | 1279 | |
7e545d6e | 1280 | mutex_unlock(&klp_mutex); |
b700e7f0 | 1281 | |
7e545d6e | 1282 | return 0; |
b700e7f0 | 1283 | |
7e545d6e JY |
1284 | err: |
1285 | /* | |
1286 | * If a patch is unsuccessfully applied, return | |
1287 | * error to the module loader. | |
1288 | */ | |
1289 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
1290 | patch->mod->name, obj->mod->name, obj->mod->name); | |
1291 | mod->klp_alive = false; | |
4ff96fb5 | 1292 | obj->mod = NULL; |
ef8daf8e | 1293 | klp_cleanup_module_patches_limited(mod, patch); |
7e545d6e JY |
1294 | mutex_unlock(&klp_mutex); |
1295 | ||
1296 | return ret; | |
b700e7f0 SJ |
1297 | } |
1298 | ||
7e545d6e | 1299 | void klp_module_going(struct module *mod) |
b700e7f0 | 1300 | { |
7e545d6e JY |
1301 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1302 | mod->state != MODULE_STATE_COMING)) | |
1303 | return; | |
b700e7f0 SJ |
1304 | |
1305 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1306 | /* |
7e545d6e JY |
1307 | * Each module has to know that klp_module_going() |
1308 | * has been called. We never know what module will | |
1309 | * get patched by a new patch. | |
8cb2c2dc | 1310 | */ |
7e545d6e | 1311 | mod->klp_alive = false; |
8cb2c2dc | 1312 | |
ef8daf8e | 1313 | klp_cleanup_module_patches_limited(mod, NULL); |
b700e7f0 SJ |
1314 | |
1315 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1316 | } |
1317 | ||
26029d88 | 1318 | static int __init klp_init(void) |
b700e7f0 | 1319 | { |
b700e7f0 | 1320 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1321 | if (!klp_root_kobj) |
1322 | return -ENOMEM; | |
b700e7f0 SJ |
1323 | |
1324 | return 0; | |
b700e7f0 SJ |
1325 | } |
1326 | ||
1327 | module_init(klp_init); |