Commit | Line | Data |
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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 | ||
9cb37357 ZL |
156 | static int klp_match_callback(void *data, unsigned long addr) |
157 | { | |
158 | struct klp_find_arg *args = data; | |
159 | ||
160 | args->addr = addr; | |
161 | args->count++; | |
162 | ||
163 | /* | |
164 | * Finish the search when the symbol is found for the desired position | |
165 | * or the position is not defined for a non-unique symbol. | |
166 | */ | |
167 | if ((args->pos && (args->count == args->pos)) || | |
168 | (!args->pos && (args->count > 1))) | |
169 | return 1; | |
170 | ||
171 | return 0; | |
172 | } | |
173 | ||
b700e7f0 | 174 | static int klp_find_object_symbol(const char *objname, const char *name, |
b2b018ef | 175 | unsigned long sympos, unsigned long *addr) |
b700e7f0 SJ |
176 | { |
177 | struct klp_find_arg args = { | |
178 | .objname = objname, | |
179 | .name = name, | |
180 | .addr = 0, | |
b2b018ef CA |
181 | .count = 0, |
182 | .pos = sympos, | |
b700e7f0 SJ |
183 | }; |
184 | ||
72f04b50 ZC |
185 | if (objname) |
186 | module_kallsyms_on_each_symbol(klp_find_callback, &args); | |
187 | else | |
9cb37357 | 188 | kallsyms_on_each_match_symbol(klp_match_callback, name, &args); |
b700e7f0 | 189 | |
b2b018ef CA |
190 | /* |
191 | * Ensure an address was found. If sympos is 0, ensure symbol is unique; | |
192 | * otherwise ensure the symbol position count matches sympos. | |
193 | */ | |
194 | if (args.addr == 0) | |
b700e7f0 | 195 | pr_err("symbol '%s' not found in symbol table\n", name); |
b2b018ef | 196 | else if (args.count > 1 && sympos == 0) { |
f995b5f7 PM |
197 | pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n", |
198 | name, objname); | |
b2b018ef CA |
199 | } else if (sympos != args.count && sympos > 0) { |
200 | pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n", | |
201 | sympos, name, objname ? objname : "vmlinux"); | |
202 | } else { | |
b700e7f0 SJ |
203 | *addr = args.addr; |
204 | return 0; | |
205 | } | |
206 | ||
207 | *addr = 0; | |
208 | return -EINVAL; | |
209 | } | |
210 | ||
2f293651 | 211 | static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, |
ca376a93 JP |
212 | unsigned int symndx, Elf_Shdr *relasec, |
213 | const char *sec_objname) | |
b700e7f0 | 214 | { |
ca376a93 JP |
215 | int i, cnt, ret; |
216 | char sym_objname[MODULE_NAME_LEN]; | |
217 | char sym_name[KSYM_NAME_LEN]; | |
425595a7 JY |
218 | Elf_Rela *relas; |
219 | Elf_Sym *sym; | |
220 | unsigned long sympos, addr; | |
ca376a93 JP |
221 | bool sym_vmlinux; |
222 | bool sec_vmlinux = !strcmp(sec_objname, "vmlinux"); | |
b700e7f0 | 223 | |
b2b018ef | 224 | /* |
ca376a93 | 225 | * Since the field widths for sym_objname and sym_name in the sscanf() |
425595a7 JY |
226 | * call are hard-coded and correspond to MODULE_NAME_LEN and |
227 | * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN | |
228 | * and KSYM_NAME_LEN have the values we expect them to have. | |
229 | * | |
230 | * Because the value of MODULE_NAME_LEN can differ among architectures, | |
231 | * we use the smallest/strictest upper bound possible (56, based on | |
232 | * the current definition of MODULE_NAME_LEN) to prevent overflows. | |
b2b018ef | 233 | */ |
b8a94bfb | 234 | BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512); |
425595a7 JY |
235 | |
236 | relas = (Elf_Rela *) relasec->sh_addr; | |
237 | /* For each rela in this klp relocation section */ | |
238 | for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { | |
2f293651 | 239 | sym = (Elf_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info); |
425595a7 | 240 | if (sym->st_shndx != SHN_LIVEPATCH) { |
77f8f39a | 241 | pr_err("symbol %s is not marked as a livepatch symbol\n", |
425595a7 JY |
242 | strtab + sym->st_name); |
243 | return -EINVAL; | |
244 | } | |
245 | ||
ca376a93 | 246 | /* Format: .klp.sym.sym_objname.sym_name,sympos */ |
425595a7 | 247 | cnt = sscanf(strtab + sym->st_name, |
b8a94bfb | 248 | ".klp.sym.%55[^.].%511[^,],%lu", |
ca376a93 | 249 | sym_objname, sym_name, &sympos); |
425595a7 | 250 | if (cnt != 3) { |
77f8f39a | 251 | pr_err("symbol %s has an incorrectly formatted name\n", |
425595a7 JY |
252 | strtab + sym->st_name); |
253 | return -EINVAL; | |
254 | } | |
255 | ||
ca376a93 JP |
256 | sym_vmlinux = !strcmp(sym_objname, "vmlinux"); |
257 | ||
258 | /* | |
259 | * Prevent module-specific KLP rela sections from referencing | |
260 | * vmlinux symbols. This helps prevent ordering issues with | |
261 | * module special section initializations. Presumably such | |
262 | * symbols are exported and normal relas can be used instead. | |
263 | */ | |
264 | if (!sec_vmlinux && sym_vmlinux) { | |
265 | pr_err("invalid access to vmlinux symbol '%s' from module-specific livepatch relocation section", | |
266 | sym_name); | |
267 | return -EINVAL; | |
268 | } | |
269 | ||
425595a7 | 270 | /* klp_find_object_symbol() treats a NULL objname as vmlinux */ |
ca376a93 JP |
271 | ret = klp_find_object_symbol(sym_vmlinux ? NULL : sym_objname, |
272 | sym_name, sympos, &addr); | |
425595a7 JY |
273 | if (ret) |
274 | return ret; | |
275 | ||
276 | sym->st_value = addr; | |
277 | } | |
278 | ||
279 | return 0; | |
b700e7f0 SJ |
280 | } |
281 | ||
7c8e2bdd JP |
282 | /* |
283 | * At a high-level, there are two types of klp relocation sections: those which | |
284 | * reference symbols which live in vmlinux; and those which reference symbols | |
285 | * which live in other modules. This function is called for both types: | |
286 | * | |
287 | * 1) When a klp module itself loads, the module code calls this function to | |
288 | * write vmlinux-specific klp relocations (.klp.rela.vmlinux.* sections). | |
289 | * These relocations are written to the klp module text to allow the patched | |
290 | * code/data to reference unexported vmlinux symbols. They're written as | |
291 | * early as possible to ensure that other module init code (.e.g., | |
292 | * jump_label_apply_nops) can access any unexported vmlinux symbols which | |
293 | * might be referenced by the klp module's special sections. | |
294 | * | |
295 | * 2) When a to-be-patched module loads -- or is already loaded when a | |
296 | * corresponding klp module loads -- klp code calls this function to write | |
297 | * module-specific klp relocations (.klp.rela.{module}.* sections). These | |
298 | * are written to the klp module text to allow the patched code/data to | |
299 | * reference symbols which live in the to-be-patched module or one of its | |
300 | * module dependencies. Exported symbols are supported, in addition to | |
301 | * unexported symbols, in order to enable late module patching, which allows | |
302 | * the to-be-patched module to be loaded and patched sometime *after* the | |
303 | * klp module is loaded. | |
304 | */ | |
305 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, | |
306 | const char *shstrtab, const char *strtab, | |
307 | unsigned int symndx, unsigned int secndx, | |
308 | const char *objname) | |
b700e7f0 | 309 | { |
7c8e2bdd | 310 | int cnt, ret; |
425595a7 | 311 | char sec_objname[MODULE_NAME_LEN]; |
7c8e2bdd | 312 | Elf_Shdr *sec = sechdrs + secndx; |
b700e7f0 | 313 | |
7c8e2bdd JP |
314 | /* |
315 | * Format: .klp.rela.sec_objname.section_name | |
316 | * See comment in klp_resolve_symbols() for an explanation | |
317 | * of the selected field width value. | |
318 | */ | |
319 | cnt = sscanf(shstrtab + sec->sh_name, ".klp.rela.%55[^.]", | |
320 | sec_objname); | |
321 | if (cnt != 1) { | |
322 | pr_err("section %s has an incorrectly formatted name\n", | |
323 | shstrtab + sec->sh_name); | |
b700e7f0 | 324 | return -EINVAL; |
7c8e2bdd | 325 | } |
b700e7f0 | 326 | |
7c8e2bdd JP |
327 | if (strcmp(objname ? objname : "vmlinux", sec_objname)) |
328 | return 0; | |
064c89df | 329 | |
ca376a93 | 330 | ret = klp_resolve_symbols(sechdrs, strtab, symndx, sec, sec_objname); |
7c8e2bdd JP |
331 | if (ret) |
332 | return ret; | |
b700e7f0 | 333 | |
7c8e2bdd | 334 | return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); |
b700e7f0 SJ |
335 | } |
336 | ||
b700e7f0 SJ |
337 | /* |
338 | * Sysfs Interface | |
339 | * | |
340 | * /sys/kernel/livepatch | |
341 | * /sys/kernel/livepatch/<patch> | |
342 | * /sys/kernel/livepatch/<patch>/enabled | |
d83a7cb3 | 343 | * /sys/kernel/livepatch/<patch>/transition |
c99a2be7 | 344 | * /sys/kernel/livepatch/<patch>/force |
b700e7f0 | 345 | * /sys/kernel/livepatch/<patch>/<object> |
bb26cfd9 | 346 | * /sys/kernel/livepatch/<patch>/<object>/patched |
444f9e99 | 347 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 | 348 | */ |
26c3e98e | 349 | static int __klp_disable_patch(struct klp_patch *patch); |
b700e7f0 SJ |
350 | |
351 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
352 | const char *buf, size_t count) | |
353 | { | |
354 | struct klp_patch *patch; | |
355 | int ret; | |
68ae4b2b | 356 | bool enabled; |
b700e7f0 | 357 | |
68ae4b2b | 358 | ret = kstrtobool(buf, &enabled); |
b700e7f0 | 359 | if (ret) |
68ae4b2b | 360 | return ret; |
b700e7f0 SJ |
361 | |
362 | patch = container_of(kobj, struct klp_patch, kobj); | |
363 | ||
364 | mutex_lock(&klp_mutex); | |
365 | ||
68ae4b2b | 366 | if (patch->enabled == enabled) { |
b700e7f0 SJ |
367 | /* already in requested state */ |
368 | ret = -EINVAL; | |
958ef1e3 | 369 | goto out; |
b700e7f0 SJ |
370 | } |
371 | ||
958ef1e3 PM |
372 | /* |
373 | * Allow to reverse a pending transition in both ways. It might be | |
374 | * necessary to complete the transition without forcing and breaking | |
375 | * the system integrity. | |
376 | * | |
377 | * Do not allow to re-enable a disabled patch. | |
378 | */ | |
379 | if (patch == klp_transition_patch) | |
d83a7cb3 | 380 | klp_reverse_transition(); |
958ef1e3 | 381 | else if (!enabled) |
b700e7f0 | 382 | ret = __klp_disable_patch(patch); |
958ef1e3 PM |
383 | else |
384 | ret = -EINVAL; | |
b700e7f0 | 385 | |
958ef1e3 | 386 | out: |
b700e7f0 SJ |
387 | mutex_unlock(&klp_mutex); |
388 | ||
958ef1e3 PM |
389 | if (ret) |
390 | return ret; | |
b700e7f0 | 391 | return count; |
b700e7f0 SJ |
392 | } |
393 | ||
394 | static ssize_t enabled_show(struct kobject *kobj, | |
395 | struct kobj_attribute *attr, char *buf) | |
396 | { | |
397 | struct klp_patch *patch; | |
398 | ||
399 | patch = container_of(kobj, struct klp_patch, kobj); | |
0dade9f3 | 400 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled); |
b700e7f0 SJ |
401 | } |
402 | ||
d83a7cb3 JP |
403 | static ssize_t transition_show(struct kobject *kobj, |
404 | struct kobj_attribute *attr, char *buf) | |
405 | { | |
406 | struct klp_patch *patch; | |
407 | ||
408 | patch = container_of(kobj, struct klp_patch, kobj); | |
409 | return snprintf(buf, PAGE_SIZE-1, "%d\n", | |
410 | patch == klp_transition_patch); | |
b700e7f0 SJ |
411 | } |
412 | ||
c99a2be7 MB |
413 | static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, |
414 | const char *buf, size_t count) | |
415 | { | |
416 | struct klp_patch *patch; | |
417 | int ret; | |
418 | bool val; | |
419 | ||
c99a2be7 MB |
420 | ret = kstrtobool(buf, &val); |
421 | if (ret) | |
422 | return ret; | |
423 | ||
8869016d MB |
424 | if (!val) |
425 | return count; | |
426 | ||
427 | mutex_lock(&klp_mutex); | |
428 | ||
429 | patch = container_of(kobj, struct klp_patch, kobj); | |
430 | if (patch != klp_transition_patch) { | |
431 | mutex_unlock(&klp_mutex); | |
432 | return -EINVAL; | |
433 | } | |
434 | ||
435 | klp_force_transition(); | |
436 | ||
437 | mutex_unlock(&klp_mutex); | |
c99a2be7 MB |
438 | |
439 | return count; | |
440 | } | |
441 | ||
b700e7f0 | 442 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); |
d83a7cb3 | 443 | static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); |
c99a2be7 | 444 | static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); |
b700e7f0 SJ |
445 | static struct attribute *klp_patch_attrs[] = { |
446 | &enabled_kobj_attr.attr, | |
d83a7cb3 | 447 | &transition_kobj_attr.attr, |
c99a2be7 | 448 | &force_kobj_attr.attr, |
b700e7f0 SJ |
449 | NULL |
450 | }; | |
70283454 | 451 | ATTRIBUTE_GROUPS(klp_patch); |
b700e7f0 | 452 | |
bb26cfd9 SL |
453 | static ssize_t patched_show(struct kobject *kobj, |
454 | struct kobj_attribute *attr, char *buf) | |
455 | { | |
456 | struct klp_object *obj; | |
457 | ||
458 | obj = container_of(kobj, struct klp_object, kobj); | |
459 | return sysfs_emit(buf, "%d\n", obj->patched); | |
460 | } | |
461 | ||
462 | static struct kobj_attribute patched_kobj_attr = __ATTR_RO(patched); | |
463 | static struct attribute *klp_object_attrs[] = { | |
464 | &patched_kobj_attr.attr, | |
465 | NULL, | |
466 | }; | |
467 | ATTRIBUTE_GROUPS(klp_object); | |
468 | ||
e1452b60 JB |
469 | static void klp_free_object_dynamic(struct klp_object *obj) |
470 | { | |
471 | kfree(obj->name); | |
472 | kfree(obj); | |
473 | } | |
474 | ||
f68d67cf PM |
475 | static void klp_init_func_early(struct klp_object *obj, |
476 | struct klp_func *func); | |
477 | static void klp_init_object_early(struct klp_patch *patch, | |
478 | struct klp_object *obj); | |
4d141ab3 | 479 | |
f68d67cf PM |
480 | static struct klp_object *klp_alloc_object_dynamic(const char *name, |
481 | struct klp_patch *patch) | |
e1452b60 JB |
482 | { |
483 | struct klp_object *obj; | |
484 | ||
485 | obj = kzalloc(sizeof(*obj), GFP_KERNEL); | |
486 | if (!obj) | |
487 | return NULL; | |
488 | ||
489 | if (name) { | |
490 | obj->name = kstrdup(name, GFP_KERNEL); | |
491 | if (!obj->name) { | |
492 | kfree(obj); | |
493 | return NULL; | |
494 | } | |
495 | } | |
496 | ||
f68d67cf | 497 | klp_init_object_early(patch, obj); |
e1452b60 JB |
498 | obj->dynamic = true; |
499 | ||
500 | return obj; | |
501 | } | |
502 | ||
503 | static void klp_free_func_nop(struct klp_func *func) | |
504 | { | |
505 | kfree(func->old_name); | |
506 | kfree(func); | |
507 | } | |
508 | ||
509 | static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func, | |
510 | struct klp_object *obj) | |
511 | { | |
512 | struct klp_func *func; | |
513 | ||
514 | func = kzalloc(sizeof(*func), GFP_KERNEL); | |
515 | if (!func) | |
516 | return NULL; | |
517 | ||
518 | if (old_func->old_name) { | |
519 | func->old_name = kstrdup(old_func->old_name, GFP_KERNEL); | |
520 | if (!func->old_name) { | |
521 | kfree(func); | |
522 | return NULL; | |
523 | } | |
524 | } | |
525 | ||
f68d67cf | 526 | klp_init_func_early(obj, func); |
e1452b60 JB |
527 | /* |
528 | * func->new_func is same as func->old_func. These addresses are | |
529 | * set when the object is loaded, see klp_init_object_loaded(). | |
530 | */ | |
531 | func->old_sympos = old_func->old_sympos; | |
532 | func->nop = true; | |
533 | ||
534 | return func; | |
535 | } | |
536 | ||
537 | static int klp_add_object_nops(struct klp_patch *patch, | |
538 | struct klp_object *old_obj) | |
539 | { | |
540 | struct klp_object *obj; | |
541 | struct klp_func *func, *old_func; | |
542 | ||
543 | obj = klp_find_object(patch, old_obj); | |
544 | ||
545 | if (!obj) { | |
f68d67cf | 546 | obj = klp_alloc_object_dynamic(old_obj->name, patch); |
e1452b60 JB |
547 | if (!obj) |
548 | return -ENOMEM; | |
e1452b60 JB |
549 | } |
550 | ||
551 | klp_for_each_func(old_obj, old_func) { | |
552 | func = klp_find_func(obj, old_func); | |
553 | if (func) | |
554 | continue; | |
555 | ||
556 | func = klp_alloc_func_nop(old_func, obj); | |
557 | if (!func) | |
558 | return -ENOMEM; | |
e1452b60 JB |
559 | } |
560 | ||
561 | return 0; | |
562 | } | |
563 | ||
564 | /* | |
565 | * Add 'nop' functions which simply return to the caller to run | |
566 | * the original function. The 'nop' functions are added to a | |
567 | * patch to facilitate a 'replace' mode. | |
568 | */ | |
569 | static int klp_add_nops(struct klp_patch *patch) | |
570 | { | |
571 | struct klp_patch *old_patch; | |
572 | struct klp_object *old_obj; | |
573 | ||
ecba29f4 | 574 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
575 | klp_for_each_object(old_patch, old_obj) { |
576 | int err; | |
577 | ||
578 | err = klp_add_object_nops(patch, old_obj); | |
579 | if (err) | |
580 | return err; | |
581 | } | |
582 | } | |
583 | ||
584 | return 0; | |
585 | } | |
586 | ||
b700e7f0 SJ |
587 | static void klp_kobj_release_patch(struct kobject *kobj) |
588 | { | |
3ec24776 JP |
589 | struct klp_patch *patch; |
590 | ||
591 | patch = container_of(kobj, struct klp_patch, kobj); | |
592 | complete(&patch->finish); | |
b700e7f0 SJ |
593 | } |
594 | ||
595 | static struct kobj_type klp_ktype_patch = { | |
596 | .release = klp_kobj_release_patch, | |
597 | .sysfs_ops = &kobj_sysfs_ops, | |
70283454 | 598 | .default_groups = klp_patch_groups, |
b700e7f0 SJ |
599 | }; |
600 | ||
cad706df MB |
601 | static void klp_kobj_release_object(struct kobject *kobj) |
602 | { | |
e1452b60 JB |
603 | struct klp_object *obj; |
604 | ||
605 | obj = container_of(kobj, struct klp_object, kobj); | |
606 | ||
607 | if (obj->dynamic) | |
608 | klp_free_object_dynamic(obj); | |
cad706df MB |
609 | } |
610 | ||
611 | static struct kobj_type klp_ktype_object = { | |
612 | .release = klp_kobj_release_object, | |
613 | .sysfs_ops = &kobj_sysfs_ops, | |
bb26cfd9 | 614 | .default_groups = klp_object_groups, |
cad706df MB |
615 | }; |
616 | ||
b700e7f0 SJ |
617 | static void klp_kobj_release_func(struct kobject *kobj) |
618 | { | |
e1452b60 JB |
619 | struct klp_func *func; |
620 | ||
621 | func = container_of(kobj, struct klp_func, kobj); | |
622 | ||
623 | if (func->nop) | |
624 | klp_free_func_nop(func); | |
b700e7f0 SJ |
625 | } |
626 | ||
627 | static struct kobj_type klp_ktype_func = { | |
628 | .release = klp_kobj_release_func, | |
629 | .sysfs_ops = &kobj_sysfs_ops, | |
630 | }; | |
631 | ||
d697bad5 | 632 | static void __klp_free_funcs(struct klp_object *obj, bool nops_only) |
b700e7f0 | 633 | { |
e1452b60 | 634 | struct klp_func *func, *tmp_func; |
b700e7f0 | 635 | |
e1452b60 | 636 | klp_for_each_func_safe(obj, func, tmp_func) { |
d697bad5 PM |
637 | if (nops_only && !func->nop) |
638 | continue; | |
639 | ||
640 | list_del(&func->node); | |
4d141ab3 | 641 | kobject_put(&func->kobj); |
0430f78b | 642 | } |
b700e7f0 SJ |
643 | } |
644 | ||
645 | /* Clean up when a patched object is unloaded */ | |
646 | static void klp_free_object_loaded(struct klp_object *obj) | |
647 | { | |
648 | struct klp_func *func; | |
649 | ||
650 | obj->mod = NULL; | |
651 | ||
e1452b60 | 652 | klp_for_each_func(obj, func) { |
19514910 | 653 | func->old_func = NULL; |
e1452b60 JB |
654 | |
655 | if (func->nop) | |
656 | func->new_func = NULL; | |
657 | } | |
b700e7f0 SJ |
658 | } |
659 | ||
d697bad5 | 660 | static void __klp_free_objects(struct klp_patch *patch, bool nops_only) |
b700e7f0 | 661 | { |
e1452b60 | 662 | struct klp_object *obj, *tmp_obj; |
b700e7f0 | 663 | |
e1452b60 | 664 | klp_for_each_object_safe(patch, obj, tmp_obj) { |
d697bad5 PM |
665 | __klp_free_funcs(obj, nops_only); |
666 | ||
667 | if (nops_only && !obj->dynamic) | |
668 | continue; | |
669 | ||
670 | list_del(&obj->node); | |
4d141ab3 | 671 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
672 | } |
673 | } | |
674 | ||
d697bad5 PM |
675 | static void klp_free_objects(struct klp_patch *patch) |
676 | { | |
677 | __klp_free_objects(patch, false); | |
678 | } | |
679 | ||
680 | static void klp_free_objects_dynamic(struct klp_patch *patch) | |
681 | { | |
682 | __klp_free_objects(patch, true); | |
683 | } | |
684 | ||
0430f78b PM |
685 | /* |
686 | * This function implements the free operations that can be called safely | |
687 | * under klp_mutex. | |
688 | * | |
689 | * The operation must be completed by calling klp_free_patch_finish() | |
690 | * outside klp_mutex. | |
691 | */ | |
7e35e4eb | 692 | static void klp_free_patch_start(struct klp_patch *patch) |
b700e7f0 | 693 | { |
b700e7f0 SJ |
694 | if (!list_empty(&patch->list)) |
695 | list_del(&patch->list); | |
0430f78b PM |
696 | |
697 | klp_free_objects(patch); | |
698 | } | |
699 | ||
700 | /* | |
701 | * This function implements the free part that must be called outside | |
702 | * klp_mutex. | |
703 | * | |
704 | * It must be called after klp_free_patch_start(). And it has to be | |
705 | * the last function accessing the livepatch structures when the patch | |
706 | * gets disabled. | |
707 | */ | |
708 | static void klp_free_patch_finish(struct klp_patch *patch) | |
709 | { | |
710 | /* | |
711 | * Avoid deadlock with enabled_store() sysfs callback by | |
712 | * calling this outside klp_mutex. It is safe because | |
713 | * this is called when the patch gets disabled and it | |
714 | * cannot get enabled again. | |
715 | */ | |
4d141ab3 PM |
716 | kobject_put(&patch->kobj); |
717 | wait_for_completion(&patch->finish); | |
958ef1e3 PM |
718 | |
719 | /* Put the module after the last access to struct klp_patch. */ | |
720 | if (!patch->forced) | |
721 | module_put(patch->mod); | |
722 | } | |
723 | ||
724 | /* | |
725 | * The livepatch might be freed from sysfs interface created by the patch. | |
726 | * This work allows to wait until the interface is destroyed in a separate | |
727 | * context. | |
728 | */ | |
729 | static void klp_free_patch_work_fn(struct work_struct *work) | |
730 | { | |
731 | struct klp_patch *patch = | |
732 | container_of(work, struct klp_patch, free_work); | |
733 | ||
734 | klp_free_patch_finish(patch); | |
b700e7f0 SJ |
735 | } |
736 | ||
7e35e4eb PM |
737 | void klp_free_patch_async(struct klp_patch *patch) |
738 | { | |
739 | klp_free_patch_start(patch); | |
740 | schedule_work(&patch->free_work); | |
741 | } | |
742 | ||
743 | void klp_free_replaced_patches_async(struct klp_patch *new_patch) | |
744 | { | |
745 | struct klp_patch *old_patch, *tmp_patch; | |
746 | ||
747 | klp_for_each_patch_safe(old_patch, tmp_patch) { | |
748 | if (old_patch == new_patch) | |
749 | return; | |
750 | klp_free_patch_async(old_patch); | |
751 | } | |
752 | } | |
753 | ||
b700e7f0 SJ |
754 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) |
755 | { | |
e1452b60 JB |
756 | if (!func->old_name) |
757 | return -EINVAL; | |
758 | ||
759 | /* | |
760 | * NOPs get the address later. The patched module must be loaded, | |
761 | * see klp_init_object_loaded(). | |
762 | */ | |
763 | if (!func->new_func && !func->nop) | |
f09d9086 MB |
764 | return -EINVAL; |
765 | ||
6e9df95b KB |
766 | if (strlen(func->old_name) >= KSYM_NAME_LEN) |
767 | return -EINVAL; | |
768 | ||
3c33f5b9 | 769 | INIT_LIST_HEAD(&func->stack_node); |
0dade9f3 | 770 | func->patched = false; |
d83a7cb3 | 771 | func->transition = false; |
b700e7f0 | 772 | |
444f9e99 CA |
773 | /* The format for the sysfs directory is <function,sympos> where sympos |
774 | * is the nth occurrence of this symbol in kallsyms for the patched | |
775 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
776 | * since a unique symbol will be the first occurrence. | |
777 | */ | |
4d141ab3 PM |
778 | return kobject_add(&func->kobj, &obj->kobj, "%s,%lu", |
779 | func->old_name, | |
780 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
781 | } |
782 | ||
a4ae16f6 SZ |
783 | static int klp_apply_object_relocs(struct klp_patch *patch, |
784 | struct klp_object *obj) | |
7c8e2bdd JP |
785 | { |
786 | int i, ret; | |
787 | struct klp_modinfo *info = patch->mod->klp_info; | |
788 | ||
789 | for (i = 1; i < info->hdr.e_shnum; i++) { | |
790 | Elf_Shdr *sec = info->sechdrs + i; | |
791 | ||
792 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
793 | continue; | |
794 | ||
795 | ret = klp_apply_section_relocs(patch->mod, info->sechdrs, | |
796 | info->secstrings, | |
797 | patch->mod->core_kallsyms.strtab, | |
798 | info->symndx, i, obj->name); | |
799 | if (ret) | |
800 | return ret; | |
801 | } | |
802 | ||
803 | return 0; | |
804 | } | |
805 | ||
b700e7f0 SJ |
806 | /* parts of the initialization that is done only when the object is loaded */ |
807 | static int klp_init_object_loaded(struct klp_patch *patch, | |
808 | struct klp_object *obj) | |
809 | { | |
810 | struct klp_func *func; | |
811 | int ret; | |
812 | ||
7c8e2bdd JP |
813 | if (klp_is_module(obj)) { |
814 | /* | |
815 | * Only write module-specific relocations here | |
816 | * (.klp.rela.{module}.*). vmlinux-specific relocations were | |
817 | * written earlier during the initialization of the klp module | |
818 | * itself. | |
819 | */ | |
820 | ret = klp_apply_object_relocs(patch, obj); | |
1d05334d PZ |
821 | if (ret) |
822 | return ret; | |
823 | } | |
9f255b63 | 824 | |
8cdd043a | 825 | klp_for_each_func(obj, func) { |
b2b018ef CA |
826 | ret = klp_find_object_symbol(obj->name, func->old_name, |
827 | func->old_sympos, | |
19514910 | 828 | (unsigned long *)&func->old_func); |
b700e7f0 SJ |
829 | if (ret) |
830 | return ret; | |
f5e547f4 | 831 | |
19514910 | 832 | ret = kallsyms_lookup_size_offset((unsigned long)func->old_func, |
f5e547f4 JP |
833 | &func->old_size, NULL); |
834 | if (!ret) { | |
835 | pr_err("kallsyms size lookup failed for '%s'\n", | |
836 | func->old_name); | |
837 | return -ENOENT; | |
838 | } | |
839 | ||
e1452b60 JB |
840 | if (func->nop) |
841 | func->new_func = func->old_func; | |
842 | ||
f5e547f4 JP |
843 | ret = kallsyms_lookup_size_offset((unsigned long)func->new_func, |
844 | &func->new_size, NULL); | |
845 | if (!ret) { | |
846 | pr_err("kallsyms size lookup failed for '%s' replacement\n", | |
847 | func->old_name); | |
848 | return -ENOENT; | |
849 | } | |
b700e7f0 SJ |
850 | } |
851 | ||
852 | return 0; | |
853 | } | |
854 | ||
855 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
856 | { | |
857 | struct klp_func *func; | |
858 | int ret; | |
859 | const char *name; | |
860 | ||
6e9df95b KB |
861 | if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN) |
862 | return -EINVAL; | |
863 | ||
0dade9f3 | 864 | obj->patched = false; |
8cb2c2dc | 865 | obj->mod = NULL; |
b700e7f0 SJ |
866 | |
867 | klp_find_object_module(obj); | |
868 | ||
869 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
4d141ab3 | 870 | ret = kobject_add(&obj->kobj, &patch->kobj, "%s", name); |
cad706df MB |
871 | if (ret) |
872 | return ret; | |
b700e7f0 | 873 | |
8cdd043a | 874 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
875 | ret = klp_init_func(obj, func); |
876 | if (ret) | |
0430f78b | 877 | return ret; |
b700e7f0 SJ |
878 | } |
879 | ||
0430f78b | 880 | if (klp_is_object_loaded(obj)) |
b700e7f0 | 881 | ret = klp_init_object_loaded(patch, obj); |
b700e7f0 | 882 | |
b700e7f0 SJ |
883 | return ret; |
884 | } | |
885 | ||
f68d67cf PM |
886 | static void klp_init_func_early(struct klp_object *obj, |
887 | struct klp_func *func) | |
888 | { | |
889 | kobject_init(&func->kobj, &klp_ktype_func); | |
890 | list_add_tail(&func->node, &obj->func_list); | |
891 | } | |
892 | ||
893 | static void klp_init_object_early(struct klp_patch *patch, | |
894 | struct klp_object *obj) | |
895 | { | |
896 | INIT_LIST_HEAD(&obj->func_list); | |
897 | kobject_init(&obj->kobj, &klp_ktype_object); | |
898 | list_add_tail(&obj->node, &patch->obj_list); | |
899 | } | |
900 | ||
5ef3dd20 | 901 | static void klp_init_patch_early(struct klp_patch *patch) |
b700e7f0 SJ |
902 | { |
903 | struct klp_object *obj; | |
0430f78b | 904 | struct klp_func *func; |
b700e7f0 | 905 | |
0430f78b | 906 | INIT_LIST_HEAD(&patch->list); |
20e55025 | 907 | INIT_LIST_HEAD(&patch->obj_list); |
4d141ab3 | 908 | kobject_init(&patch->kobj, &klp_ktype_patch); |
0dade9f3 | 909 | patch->enabled = false; |
68007289 | 910 | patch->forced = false; |
958ef1e3 | 911 | INIT_WORK(&patch->free_work, klp_free_patch_work_fn); |
3ec24776 | 912 | init_completion(&patch->finish); |
b700e7f0 | 913 | |
20e55025 | 914 | klp_for_each_object_static(patch, obj) { |
f68d67cf | 915 | klp_init_object_early(patch, obj); |
0430f78b | 916 | |
20e55025 | 917 | klp_for_each_func_static(obj, func) { |
f68d67cf | 918 | klp_init_func_early(obj, func); |
20e55025 | 919 | } |
0430f78b | 920 | } |
0430f78b PM |
921 | } |
922 | ||
923 | static int klp_init_patch(struct klp_patch *patch) | |
924 | { | |
925 | struct klp_object *obj; | |
926 | int ret; | |
927 | ||
4d141ab3 | 928 | ret = kobject_add(&patch->kobj, klp_root_kobj, "%s", patch->mod->name); |
958ef1e3 | 929 | if (ret) |
3ec24776 | 930 | return ret; |
b700e7f0 | 931 | |
e1452b60 JB |
932 | if (patch->replace) { |
933 | ret = klp_add_nops(patch); | |
934 | if (ret) | |
935 | return ret; | |
936 | } | |
937 | ||
8cdd043a | 938 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
939 | ret = klp_init_object(patch, obj); |
940 | if (ret) | |
958ef1e3 | 941 | return ret; |
b700e7f0 SJ |
942 | } |
943 | ||
99590ba5 | 944 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 | 945 | |
3ec24776 | 946 | return 0; |
b700e7f0 | 947 | } |
b700e7f0 | 948 | |
26c3e98e PM |
949 | static int __klp_disable_patch(struct klp_patch *patch) |
950 | { | |
951 | struct klp_object *obj; | |
952 | ||
953 | if (WARN_ON(!patch->enabled)) | |
954 | return -EINVAL; | |
955 | ||
956 | if (klp_transition_patch) | |
957 | return -EBUSY; | |
958 | ||
26c3e98e PM |
959 | klp_init_transition(patch, KLP_UNPATCHED); |
960 | ||
961 | klp_for_each_object(patch, obj) | |
962 | if (obj->patched) | |
963 | klp_pre_unpatch_callback(obj); | |
964 | ||
965 | /* | |
966 | * Enforce the order of the func->transition writes in | |
967 | * klp_init_transition() and the TIF_PATCH_PENDING writes in | |
968 | * klp_start_transition(). In the rare case where klp_ftrace_handler() | |
969 | * is called shortly after klp_update_patch_state() switches the task, | |
970 | * this ensures the handler sees that func->transition is set. | |
971 | */ | |
972 | smp_wmb(); | |
973 | ||
974 | klp_start_transition(); | |
26c3e98e | 975 | patch->enabled = false; |
958ef1e3 | 976 | klp_try_complete_transition(); |
26c3e98e PM |
977 | |
978 | return 0; | |
979 | } | |
980 | ||
26c3e98e PM |
981 | static int __klp_enable_patch(struct klp_patch *patch) |
982 | { | |
983 | struct klp_object *obj; | |
984 | int ret; | |
985 | ||
986 | if (klp_transition_patch) | |
987 | return -EBUSY; | |
988 | ||
989 | if (WARN_ON(patch->enabled)) | |
990 | return -EINVAL; | |
991 | ||
26c3e98e PM |
992 | pr_notice("enabling patch '%s'\n", patch->mod->name); |
993 | ||
994 | klp_init_transition(patch, KLP_PATCHED); | |
995 | ||
996 | /* | |
997 | * Enforce the order of the func->transition writes in | |
998 | * klp_init_transition() and the ops->func_stack writes in | |
999 | * klp_patch_object(), so that klp_ftrace_handler() will see the | |
1000 | * func->transition updates before the handler is registered and the | |
1001 | * new funcs become visible to the handler. | |
1002 | */ | |
1003 | smp_wmb(); | |
1004 | ||
1005 | klp_for_each_object(patch, obj) { | |
1006 | if (!klp_is_object_loaded(obj)) | |
1007 | continue; | |
1008 | ||
1009 | ret = klp_pre_patch_callback(obj); | |
1010 | if (ret) { | |
1011 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1012 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
1013 | goto err; | |
1014 | } | |
1015 | ||
1016 | ret = klp_patch_object(obj); | |
1017 | if (ret) { | |
1018 | pr_warn("failed to patch object '%s'\n", | |
1019 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
1020 | goto err; | |
1021 | } | |
1022 | } | |
1023 | ||
1024 | klp_start_transition(); | |
26c3e98e | 1025 | patch->enabled = true; |
958ef1e3 | 1026 | klp_try_complete_transition(); |
26c3e98e PM |
1027 | |
1028 | return 0; | |
1029 | err: | |
1030 | pr_warn("failed to enable patch '%s'\n", patch->mod->name); | |
1031 | ||
1032 | klp_cancel_transition(); | |
1033 | return ret; | |
1034 | } | |
1035 | ||
1036 | /** | |
958ef1e3 PM |
1037 | * klp_enable_patch() - enable the livepatch |
1038 | * @patch: patch to be enabled | |
26c3e98e | 1039 | * |
958ef1e3 PM |
1040 | * Initializes the data structure associated with the patch, creates the sysfs |
1041 | * interface, performs the needed symbol lookups and code relocations, | |
1042 | * registers the patched functions with ftrace. | |
1043 | * | |
1044 | * This function is supposed to be called from the livepatch module_init() | |
1045 | * callback. | |
26c3e98e PM |
1046 | * |
1047 | * Return: 0 on success, otherwise error | |
1048 | */ | |
1049 | int klp_enable_patch(struct klp_patch *patch) | |
1050 | { | |
1051 | int ret; | |
5ef3dd20 | 1052 | struct klp_object *obj; |
26c3e98e | 1053 | |
5ef3dd20 | 1054 | if (!patch || !patch->mod || !patch->objs) |
958ef1e3 PM |
1055 | return -EINVAL; |
1056 | ||
5ef3dd20 DV |
1057 | klp_for_each_object_static(patch, obj) { |
1058 | if (!obj->funcs) | |
1059 | return -EINVAL; | |
1060 | } | |
1061 | ||
1062 | ||
958ef1e3 PM |
1063 | if (!is_livepatch_module(patch->mod)) { |
1064 | pr_err("module %s is not marked as a livepatch module\n", | |
1065 | patch->mod->name); | |
1066 | return -EINVAL; | |
1067 | } | |
1068 | ||
1069 | if (!klp_initialized()) | |
1070 | return -ENODEV; | |
1071 | ||
1072 | if (!klp_have_reliable_stack()) { | |
31adf230 PM |
1073 | pr_warn("This architecture doesn't have support for the livepatch consistency model.\n"); |
1074 | pr_warn("The livepatch transition may never complete.\n"); | |
958ef1e3 PM |
1075 | } |
1076 | ||
26c3e98e PM |
1077 | mutex_lock(&klp_mutex); |
1078 | ||
92c9abf5 PM |
1079 | if (!klp_is_patch_compatible(patch)) { |
1080 | pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n", | |
1081 | patch->mod->name); | |
1082 | mutex_unlock(&klp_mutex); | |
1083 | return -EINVAL; | |
1084 | } | |
1085 | ||
50a0f3f5 YY |
1086 | if (!try_module_get(patch->mod)) { |
1087 | mutex_unlock(&klp_mutex); | |
5ef3dd20 | 1088 | return -ENODEV; |
50a0f3f5 | 1089 | } |
5ef3dd20 DV |
1090 | |
1091 | klp_init_patch_early(patch); | |
26c3e98e | 1092 | |
958ef1e3 PM |
1093 | ret = klp_init_patch(patch); |
1094 | if (ret) | |
1095 | goto err; | |
1096 | ||
26c3e98e | 1097 | ret = __klp_enable_patch(patch); |
958ef1e3 PM |
1098 | if (ret) |
1099 | goto err; | |
1100 | ||
1101 | mutex_unlock(&klp_mutex); | |
1102 | ||
1103 | return 0; | |
26c3e98e PM |
1104 | |
1105 | err: | |
958ef1e3 PM |
1106 | klp_free_patch_start(patch); |
1107 | ||
26c3e98e | 1108 | mutex_unlock(&klp_mutex); |
958ef1e3 PM |
1109 | |
1110 | klp_free_patch_finish(patch); | |
1111 | ||
26c3e98e PM |
1112 | return ret; |
1113 | } | |
1114 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
1115 | ||
e1452b60 | 1116 | /* |
7e35e4eb | 1117 | * This function unpatches objects from the replaced livepatches. |
e1452b60 JB |
1118 | * |
1119 | * We could be pretty aggressive here. It is called in the situation where | |
7e35e4eb PM |
1120 | * these structures are no longer accessed from the ftrace handler. |
1121 | * All functions are redirected by the klp_transition_patch. They | |
1122 | * use either a new code or they are in the original code because | |
1123 | * of the special nop function patches. | |
e1452b60 JB |
1124 | * |
1125 | * The only exception is when the transition was forced. In this case, | |
1126 | * klp_ftrace_handler() might still see the replaced patch on the stack. | |
1127 | * Fortunately, it is carefully designed to work with removed functions | |
1128 | * thanks to RCU. We only have to keep the patches on the system. Also | |
1129 | * this is handled transparently by patch->module_put. | |
1130 | */ | |
7e35e4eb | 1131 | void klp_unpatch_replaced_patches(struct klp_patch *new_patch) |
e1452b60 | 1132 | { |
7e35e4eb | 1133 | struct klp_patch *old_patch; |
e1452b60 | 1134 | |
7e35e4eb | 1135 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
1136 | if (old_patch == new_patch) |
1137 | return; | |
1138 | ||
1139 | old_patch->enabled = false; | |
1140 | klp_unpatch_objects(old_patch); | |
e1452b60 JB |
1141 | } |
1142 | } | |
1143 | ||
d697bad5 PM |
1144 | /* |
1145 | * This function removes the dynamically allocated 'nop' functions. | |
1146 | * | |
1147 | * We could be pretty aggressive. NOPs do not change the existing | |
1148 | * behavior except for adding unnecessary delay by the ftrace handler. | |
1149 | * | |
1150 | * It is safe even when the transition was forced. The ftrace handler | |
1151 | * will see a valid ops->func_stack entry thanks to RCU. | |
1152 | * | |
1153 | * We could even free the NOPs structures. They must be the last entry | |
1154 | * in ops->func_stack. Therefore unregister_ftrace_function() is called. | |
1155 | * It does the same as klp_synchronize_transition() to make sure that | |
1156 | * nobody is inside the ftrace handler once the operation finishes. | |
1157 | * | |
1158 | * IMPORTANT: It must be called right after removing the replaced patches! | |
1159 | */ | |
1160 | void klp_discard_nops(struct klp_patch *new_patch) | |
1161 | { | |
1162 | klp_unpatch_objects_dynamic(klp_transition_patch); | |
1163 | klp_free_objects_dynamic(klp_transition_patch); | |
1164 | } | |
1165 | ||
ef8daf8e JL |
1166 | /* |
1167 | * Remove parts of patches that touch a given kernel module. The list of | |
1168 | * patches processed might be limited. When limit is NULL, all patches | |
1169 | * will be handled. | |
1170 | */ | |
1171 | static void klp_cleanup_module_patches_limited(struct module *mod, | |
1172 | struct klp_patch *limit) | |
1173 | { | |
1174 | struct klp_patch *patch; | |
1175 | struct klp_object *obj; | |
1176 | ||
ecba29f4 | 1177 | klp_for_each_patch(patch) { |
ef8daf8e JL |
1178 | if (patch == limit) |
1179 | break; | |
1180 | ||
1181 | klp_for_each_object(patch, obj) { | |
1182 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1183 | continue; | |
1184 | ||
a087cdd4 PM |
1185 | if (patch != klp_transition_patch) |
1186 | klp_pre_unpatch_callback(obj); | |
fc41efc1 | 1187 | |
a087cdd4 PM |
1188 | pr_notice("reverting patch '%s' on unloading module '%s'\n", |
1189 | patch->mod->name, obj->mod->name); | |
1190 | klp_unpatch_object(obj); | |
fc41efc1 | 1191 | |
a087cdd4 | 1192 | klp_post_unpatch_callback(obj); |
ef8daf8e JL |
1193 | |
1194 | klp_free_object_loaded(obj); | |
1195 | break; | |
1196 | } | |
1197 | } | |
1198 | } | |
1199 | ||
7e545d6e | 1200 | int klp_module_coming(struct module *mod) |
b700e7f0 | 1201 | { |
b700e7f0 | 1202 | int ret; |
7e545d6e JY |
1203 | struct klp_patch *patch; |
1204 | struct klp_object *obj; | |
b700e7f0 | 1205 | |
7e545d6e JY |
1206 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
1207 | return -EINVAL; | |
b700e7f0 | 1208 | |
dcf550e5 | 1209 | if (!strcmp(mod->name, "vmlinux")) { |
66d8529d | 1210 | pr_err("vmlinux.ko: invalid module name\n"); |
dcf550e5 JP |
1211 | return -EINVAL; |
1212 | } | |
1213 | ||
7e545d6e JY |
1214 | mutex_lock(&klp_mutex); |
1215 | /* | |
1216 | * Each module has to know that klp_module_coming() | |
1217 | * has been called. We never know what module will | |
1218 | * get patched by a new patch. | |
1219 | */ | |
1220 | mod->klp_alive = true; | |
b700e7f0 | 1221 | |
ecba29f4 | 1222 | klp_for_each_patch(patch) { |
7e545d6e JY |
1223 | klp_for_each_object(patch, obj) { |
1224 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1225 | continue; | |
b700e7f0 | 1226 | |
7e545d6e | 1227 | obj->mod = mod; |
b700e7f0 | 1228 | |
7e545d6e JY |
1229 | ret = klp_init_object_loaded(patch, obj); |
1230 | if (ret) { | |
1231 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
1232 | patch->mod->name, obj->mod->name, ret); | |
1233 | goto err; | |
1234 | } | |
b700e7f0 | 1235 | |
7e545d6e JY |
1236 | pr_notice("applying patch '%s' to loading module '%s'\n", |
1237 | patch->mod->name, obj->mod->name); | |
1238 | ||
93862e38 JL |
1239 | ret = klp_pre_patch_callback(obj); |
1240 | if (ret) { | |
1241 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1242 | obj->name); | |
1243 | goto err; | |
1244 | } | |
1245 | ||
0dade9f3 | 1246 | ret = klp_patch_object(obj); |
7e545d6e JY |
1247 | if (ret) { |
1248 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
1249 | patch->mod->name, obj->mod->name, ret); | |
93862e38 | 1250 | |
5aaf1ab5 | 1251 | klp_post_unpatch_callback(obj); |
7e545d6e JY |
1252 | goto err; |
1253 | } | |
1254 | ||
93862e38 JL |
1255 | if (patch != klp_transition_patch) |
1256 | klp_post_patch_callback(obj); | |
1257 | ||
7e545d6e JY |
1258 | break; |
1259 | } | |
1260 | } | |
b700e7f0 | 1261 | |
7e545d6e | 1262 | mutex_unlock(&klp_mutex); |
b700e7f0 | 1263 | |
7e545d6e | 1264 | return 0; |
b700e7f0 | 1265 | |
7e545d6e JY |
1266 | err: |
1267 | /* | |
1268 | * If a patch is unsuccessfully applied, return | |
1269 | * error to the module loader. | |
1270 | */ | |
1271 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
1272 | patch->mod->name, obj->mod->name, obj->mod->name); | |
1273 | mod->klp_alive = false; | |
4ff96fb5 | 1274 | obj->mod = NULL; |
ef8daf8e | 1275 | klp_cleanup_module_patches_limited(mod, patch); |
7e545d6e JY |
1276 | mutex_unlock(&klp_mutex); |
1277 | ||
1278 | return ret; | |
b700e7f0 SJ |
1279 | } |
1280 | ||
7e545d6e | 1281 | void klp_module_going(struct module *mod) |
b700e7f0 | 1282 | { |
7e545d6e JY |
1283 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1284 | mod->state != MODULE_STATE_COMING)) | |
1285 | return; | |
b700e7f0 SJ |
1286 | |
1287 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1288 | /* |
7e545d6e JY |
1289 | * Each module has to know that klp_module_going() |
1290 | * has been called. We never know what module will | |
1291 | * get patched by a new patch. | |
8cb2c2dc | 1292 | */ |
7e545d6e | 1293 | mod->klp_alive = false; |
8cb2c2dc | 1294 | |
ef8daf8e | 1295 | klp_cleanup_module_patches_limited(mod, NULL); |
b700e7f0 SJ |
1296 | |
1297 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1298 | } |
1299 | ||
26029d88 | 1300 | static int __init klp_init(void) |
b700e7f0 | 1301 | { |
b700e7f0 | 1302 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1303 | if (!klp_root_kobj) |
1304 | return -ENOMEM; | |
b700e7f0 SJ |
1305 | |
1306 | return 0; | |
b700e7f0 SJ |
1307 | } |
1308 | ||
1309 | module_init(klp_init); |