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 | ||
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 | ||
7c8e2bdd | 193 | static int klp_resolve_symbols(Elf64_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 | */ |
425595a7 JY |
216 | BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); |
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++) { | |
7c8e2bdd | 221 | sym = (Elf64_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 JY |
229 | cnt = sscanf(strtab + sym->st_name, |
230 | ".klp.sym.%55[^.].%127[^,],%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 | ||
7c8e2bdd JP |
264 | /* |
265 | * At a high-level, there are two types of klp relocation sections: those which | |
266 | * reference symbols which live in vmlinux; and those which reference symbols | |
267 | * which live in other modules. This function is called for both types: | |
268 | * | |
269 | * 1) When a klp module itself loads, the module code calls this function to | |
270 | * write vmlinux-specific klp relocations (.klp.rela.vmlinux.* sections). | |
271 | * These relocations are written to the klp module text to allow the patched | |
272 | * code/data to reference unexported vmlinux symbols. They're written as | |
273 | * early as possible to ensure that other module init code (.e.g., | |
274 | * jump_label_apply_nops) can access any unexported vmlinux symbols which | |
275 | * might be referenced by the klp module's special sections. | |
276 | * | |
277 | * 2) When a to-be-patched module loads -- or is already loaded when a | |
278 | * corresponding klp module loads -- klp code calls this function to write | |
279 | * module-specific klp relocations (.klp.rela.{module}.* sections). These | |
280 | * are written to the klp module text to allow the patched code/data to | |
281 | * reference symbols which live in the to-be-patched module or one of its | |
282 | * module dependencies. Exported symbols are supported, in addition to | |
283 | * unexported symbols, in order to enable late module patching, which allows | |
284 | * the to-be-patched module to be loaded and patched sometime *after* the | |
285 | * klp module is loaded. | |
286 | */ | |
287 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, | |
288 | const char *shstrtab, const char *strtab, | |
289 | unsigned int symndx, unsigned int secndx, | |
290 | const char *objname) | |
b700e7f0 | 291 | { |
7c8e2bdd | 292 | int cnt, ret; |
425595a7 | 293 | char sec_objname[MODULE_NAME_LEN]; |
7c8e2bdd | 294 | Elf_Shdr *sec = sechdrs + secndx; |
b700e7f0 | 295 | |
7c8e2bdd JP |
296 | /* |
297 | * Format: .klp.rela.sec_objname.section_name | |
298 | * See comment in klp_resolve_symbols() for an explanation | |
299 | * of the selected field width value. | |
300 | */ | |
301 | cnt = sscanf(shstrtab + sec->sh_name, ".klp.rela.%55[^.]", | |
302 | sec_objname); | |
303 | if (cnt != 1) { | |
304 | pr_err("section %s has an incorrectly formatted name\n", | |
305 | shstrtab + sec->sh_name); | |
b700e7f0 | 306 | return -EINVAL; |
7c8e2bdd | 307 | } |
b700e7f0 | 308 | |
7c8e2bdd JP |
309 | if (strcmp(objname ? objname : "vmlinux", sec_objname)) |
310 | return 0; | |
064c89df | 311 | |
ca376a93 | 312 | ret = klp_resolve_symbols(sechdrs, strtab, symndx, sec, sec_objname); |
7c8e2bdd JP |
313 | if (ret) |
314 | return ret; | |
b700e7f0 | 315 | |
7c8e2bdd | 316 | return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); |
b700e7f0 SJ |
317 | } |
318 | ||
b700e7f0 SJ |
319 | /* |
320 | * Sysfs Interface | |
321 | * | |
322 | * /sys/kernel/livepatch | |
323 | * /sys/kernel/livepatch/<patch> | |
324 | * /sys/kernel/livepatch/<patch>/enabled | |
d83a7cb3 | 325 | * /sys/kernel/livepatch/<patch>/transition |
c99a2be7 | 326 | * /sys/kernel/livepatch/<patch>/force |
b700e7f0 | 327 | * /sys/kernel/livepatch/<patch>/<object> |
444f9e99 | 328 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 | 329 | */ |
26c3e98e | 330 | static int __klp_disable_patch(struct klp_patch *patch); |
b700e7f0 SJ |
331 | |
332 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
333 | const char *buf, size_t count) | |
334 | { | |
335 | struct klp_patch *patch; | |
336 | int ret; | |
68ae4b2b | 337 | bool enabled; |
b700e7f0 | 338 | |
68ae4b2b | 339 | ret = kstrtobool(buf, &enabled); |
b700e7f0 | 340 | if (ret) |
68ae4b2b | 341 | return ret; |
b700e7f0 SJ |
342 | |
343 | patch = container_of(kobj, struct klp_patch, kobj); | |
344 | ||
345 | mutex_lock(&klp_mutex); | |
346 | ||
68ae4b2b | 347 | if (patch->enabled == enabled) { |
b700e7f0 SJ |
348 | /* already in requested state */ |
349 | ret = -EINVAL; | |
958ef1e3 | 350 | goto out; |
b700e7f0 SJ |
351 | } |
352 | ||
958ef1e3 PM |
353 | /* |
354 | * Allow to reverse a pending transition in both ways. It might be | |
355 | * necessary to complete the transition without forcing and breaking | |
356 | * the system integrity. | |
357 | * | |
358 | * Do not allow to re-enable a disabled patch. | |
359 | */ | |
360 | if (patch == klp_transition_patch) | |
d83a7cb3 | 361 | klp_reverse_transition(); |
958ef1e3 | 362 | else if (!enabled) |
b700e7f0 | 363 | ret = __klp_disable_patch(patch); |
958ef1e3 PM |
364 | else |
365 | ret = -EINVAL; | |
b700e7f0 | 366 | |
958ef1e3 | 367 | out: |
b700e7f0 SJ |
368 | mutex_unlock(&klp_mutex); |
369 | ||
958ef1e3 PM |
370 | if (ret) |
371 | return ret; | |
b700e7f0 | 372 | return count; |
b700e7f0 SJ |
373 | } |
374 | ||
375 | static ssize_t enabled_show(struct kobject *kobj, | |
376 | struct kobj_attribute *attr, char *buf) | |
377 | { | |
378 | struct klp_patch *patch; | |
379 | ||
380 | patch = container_of(kobj, struct klp_patch, kobj); | |
0dade9f3 | 381 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled); |
b700e7f0 SJ |
382 | } |
383 | ||
d83a7cb3 JP |
384 | static ssize_t transition_show(struct kobject *kobj, |
385 | struct kobj_attribute *attr, char *buf) | |
386 | { | |
387 | struct klp_patch *patch; | |
388 | ||
389 | patch = container_of(kobj, struct klp_patch, kobj); | |
390 | return snprintf(buf, PAGE_SIZE-1, "%d\n", | |
391 | patch == klp_transition_patch); | |
b700e7f0 SJ |
392 | } |
393 | ||
c99a2be7 MB |
394 | static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, |
395 | const char *buf, size_t count) | |
396 | { | |
397 | struct klp_patch *patch; | |
398 | int ret; | |
399 | bool val; | |
400 | ||
c99a2be7 MB |
401 | ret = kstrtobool(buf, &val); |
402 | if (ret) | |
403 | return ret; | |
404 | ||
8869016d MB |
405 | if (!val) |
406 | return count; | |
407 | ||
408 | mutex_lock(&klp_mutex); | |
409 | ||
410 | patch = container_of(kobj, struct klp_patch, kobj); | |
411 | if (patch != klp_transition_patch) { | |
412 | mutex_unlock(&klp_mutex); | |
413 | return -EINVAL; | |
414 | } | |
415 | ||
416 | klp_force_transition(); | |
417 | ||
418 | mutex_unlock(&klp_mutex); | |
c99a2be7 MB |
419 | |
420 | return count; | |
421 | } | |
422 | ||
b700e7f0 | 423 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); |
d83a7cb3 | 424 | static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); |
c99a2be7 | 425 | static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); |
b700e7f0 SJ |
426 | static struct attribute *klp_patch_attrs[] = { |
427 | &enabled_kobj_attr.attr, | |
d83a7cb3 | 428 | &transition_kobj_attr.attr, |
c99a2be7 | 429 | &force_kobj_attr.attr, |
b700e7f0 SJ |
430 | NULL |
431 | }; | |
70283454 | 432 | ATTRIBUTE_GROUPS(klp_patch); |
b700e7f0 | 433 | |
e1452b60 JB |
434 | static void klp_free_object_dynamic(struct klp_object *obj) |
435 | { | |
436 | kfree(obj->name); | |
437 | kfree(obj); | |
438 | } | |
439 | ||
f68d67cf PM |
440 | static void klp_init_func_early(struct klp_object *obj, |
441 | struct klp_func *func); | |
442 | static void klp_init_object_early(struct klp_patch *patch, | |
443 | struct klp_object *obj); | |
4d141ab3 | 444 | |
f68d67cf PM |
445 | static struct klp_object *klp_alloc_object_dynamic(const char *name, |
446 | struct klp_patch *patch) | |
e1452b60 JB |
447 | { |
448 | struct klp_object *obj; | |
449 | ||
450 | obj = kzalloc(sizeof(*obj), GFP_KERNEL); | |
451 | if (!obj) | |
452 | return NULL; | |
453 | ||
454 | if (name) { | |
455 | obj->name = kstrdup(name, GFP_KERNEL); | |
456 | if (!obj->name) { | |
457 | kfree(obj); | |
458 | return NULL; | |
459 | } | |
460 | } | |
461 | ||
f68d67cf | 462 | klp_init_object_early(patch, obj); |
e1452b60 JB |
463 | obj->dynamic = true; |
464 | ||
465 | return obj; | |
466 | } | |
467 | ||
468 | static void klp_free_func_nop(struct klp_func *func) | |
469 | { | |
470 | kfree(func->old_name); | |
471 | kfree(func); | |
472 | } | |
473 | ||
474 | static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func, | |
475 | struct klp_object *obj) | |
476 | { | |
477 | struct klp_func *func; | |
478 | ||
479 | func = kzalloc(sizeof(*func), GFP_KERNEL); | |
480 | if (!func) | |
481 | return NULL; | |
482 | ||
483 | if (old_func->old_name) { | |
484 | func->old_name = kstrdup(old_func->old_name, GFP_KERNEL); | |
485 | if (!func->old_name) { | |
486 | kfree(func); | |
487 | return NULL; | |
488 | } | |
489 | } | |
490 | ||
f68d67cf | 491 | klp_init_func_early(obj, func); |
e1452b60 JB |
492 | /* |
493 | * func->new_func is same as func->old_func. These addresses are | |
494 | * set when the object is loaded, see klp_init_object_loaded(). | |
495 | */ | |
496 | func->old_sympos = old_func->old_sympos; | |
497 | func->nop = true; | |
498 | ||
499 | return func; | |
500 | } | |
501 | ||
502 | static int klp_add_object_nops(struct klp_patch *patch, | |
503 | struct klp_object *old_obj) | |
504 | { | |
505 | struct klp_object *obj; | |
506 | struct klp_func *func, *old_func; | |
507 | ||
508 | obj = klp_find_object(patch, old_obj); | |
509 | ||
510 | if (!obj) { | |
f68d67cf | 511 | obj = klp_alloc_object_dynamic(old_obj->name, patch); |
e1452b60 JB |
512 | if (!obj) |
513 | return -ENOMEM; | |
e1452b60 JB |
514 | } |
515 | ||
516 | klp_for_each_func(old_obj, old_func) { | |
517 | func = klp_find_func(obj, old_func); | |
518 | if (func) | |
519 | continue; | |
520 | ||
521 | func = klp_alloc_func_nop(old_func, obj); | |
522 | if (!func) | |
523 | return -ENOMEM; | |
e1452b60 JB |
524 | } |
525 | ||
526 | return 0; | |
527 | } | |
528 | ||
529 | /* | |
530 | * Add 'nop' functions which simply return to the caller to run | |
531 | * the original function. The 'nop' functions are added to a | |
532 | * patch to facilitate a 'replace' mode. | |
533 | */ | |
534 | static int klp_add_nops(struct klp_patch *patch) | |
535 | { | |
536 | struct klp_patch *old_patch; | |
537 | struct klp_object *old_obj; | |
538 | ||
ecba29f4 | 539 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
540 | klp_for_each_object(old_patch, old_obj) { |
541 | int err; | |
542 | ||
543 | err = klp_add_object_nops(patch, old_obj); | |
544 | if (err) | |
545 | return err; | |
546 | } | |
547 | } | |
548 | ||
549 | return 0; | |
550 | } | |
551 | ||
b700e7f0 SJ |
552 | static void klp_kobj_release_patch(struct kobject *kobj) |
553 | { | |
3ec24776 JP |
554 | struct klp_patch *patch; |
555 | ||
556 | patch = container_of(kobj, struct klp_patch, kobj); | |
557 | complete(&patch->finish); | |
b700e7f0 SJ |
558 | } |
559 | ||
560 | static struct kobj_type klp_ktype_patch = { | |
561 | .release = klp_kobj_release_patch, | |
562 | .sysfs_ops = &kobj_sysfs_ops, | |
70283454 | 563 | .default_groups = klp_patch_groups, |
b700e7f0 SJ |
564 | }; |
565 | ||
cad706df MB |
566 | static void klp_kobj_release_object(struct kobject *kobj) |
567 | { | |
e1452b60 JB |
568 | struct klp_object *obj; |
569 | ||
570 | obj = container_of(kobj, struct klp_object, kobj); | |
571 | ||
572 | if (obj->dynamic) | |
573 | klp_free_object_dynamic(obj); | |
cad706df MB |
574 | } |
575 | ||
576 | static struct kobj_type klp_ktype_object = { | |
577 | .release = klp_kobj_release_object, | |
578 | .sysfs_ops = &kobj_sysfs_ops, | |
579 | }; | |
580 | ||
b700e7f0 SJ |
581 | static void klp_kobj_release_func(struct kobject *kobj) |
582 | { | |
e1452b60 JB |
583 | struct klp_func *func; |
584 | ||
585 | func = container_of(kobj, struct klp_func, kobj); | |
586 | ||
587 | if (func->nop) | |
588 | klp_free_func_nop(func); | |
b700e7f0 SJ |
589 | } |
590 | ||
591 | static struct kobj_type klp_ktype_func = { | |
592 | .release = klp_kobj_release_func, | |
593 | .sysfs_ops = &kobj_sysfs_ops, | |
594 | }; | |
595 | ||
d697bad5 | 596 | static void __klp_free_funcs(struct klp_object *obj, bool nops_only) |
b700e7f0 | 597 | { |
e1452b60 | 598 | struct klp_func *func, *tmp_func; |
b700e7f0 | 599 | |
e1452b60 | 600 | klp_for_each_func_safe(obj, func, tmp_func) { |
d697bad5 PM |
601 | if (nops_only && !func->nop) |
602 | continue; | |
603 | ||
604 | list_del(&func->node); | |
4d141ab3 | 605 | kobject_put(&func->kobj); |
0430f78b | 606 | } |
b700e7f0 SJ |
607 | } |
608 | ||
609 | /* Clean up when a patched object is unloaded */ | |
610 | static void klp_free_object_loaded(struct klp_object *obj) | |
611 | { | |
612 | struct klp_func *func; | |
613 | ||
614 | obj->mod = NULL; | |
615 | ||
e1452b60 | 616 | klp_for_each_func(obj, func) { |
19514910 | 617 | func->old_func = NULL; |
e1452b60 JB |
618 | |
619 | if (func->nop) | |
620 | func->new_func = NULL; | |
621 | } | |
b700e7f0 SJ |
622 | } |
623 | ||
d697bad5 | 624 | static void __klp_free_objects(struct klp_patch *patch, bool nops_only) |
b700e7f0 | 625 | { |
e1452b60 | 626 | struct klp_object *obj, *tmp_obj; |
b700e7f0 | 627 | |
e1452b60 | 628 | klp_for_each_object_safe(patch, obj, tmp_obj) { |
d697bad5 PM |
629 | __klp_free_funcs(obj, nops_only); |
630 | ||
631 | if (nops_only && !obj->dynamic) | |
632 | continue; | |
633 | ||
634 | list_del(&obj->node); | |
4d141ab3 | 635 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
636 | } |
637 | } | |
638 | ||
d697bad5 PM |
639 | static void klp_free_objects(struct klp_patch *patch) |
640 | { | |
641 | __klp_free_objects(patch, false); | |
642 | } | |
643 | ||
644 | static void klp_free_objects_dynamic(struct klp_patch *patch) | |
645 | { | |
646 | __klp_free_objects(patch, true); | |
647 | } | |
648 | ||
0430f78b PM |
649 | /* |
650 | * This function implements the free operations that can be called safely | |
651 | * under klp_mutex. | |
652 | * | |
653 | * The operation must be completed by calling klp_free_patch_finish() | |
654 | * outside klp_mutex. | |
655 | */ | |
7e35e4eb | 656 | static void klp_free_patch_start(struct klp_patch *patch) |
b700e7f0 | 657 | { |
b700e7f0 SJ |
658 | if (!list_empty(&patch->list)) |
659 | list_del(&patch->list); | |
0430f78b PM |
660 | |
661 | klp_free_objects(patch); | |
662 | } | |
663 | ||
664 | /* | |
665 | * This function implements the free part that must be called outside | |
666 | * klp_mutex. | |
667 | * | |
668 | * It must be called after klp_free_patch_start(). And it has to be | |
669 | * the last function accessing the livepatch structures when the patch | |
670 | * gets disabled. | |
671 | */ | |
672 | static void klp_free_patch_finish(struct klp_patch *patch) | |
673 | { | |
674 | /* | |
675 | * Avoid deadlock with enabled_store() sysfs callback by | |
676 | * calling this outside klp_mutex. It is safe because | |
677 | * this is called when the patch gets disabled and it | |
678 | * cannot get enabled again. | |
679 | */ | |
4d141ab3 PM |
680 | kobject_put(&patch->kobj); |
681 | wait_for_completion(&patch->finish); | |
958ef1e3 PM |
682 | |
683 | /* Put the module after the last access to struct klp_patch. */ | |
684 | if (!patch->forced) | |
685 | module_put(patch->mod); | |
686 | } | |
687 | ||
688 | /* | |
689 | * The livepatch might be freed from sysfs interface created by the patch. | |
690 | * This work allows to wait until the interface is destroyed in a separate | |
691 | * context. | |
692 | */ | |
693 | static void klp_free_patch_work_fn(struct work_struct *work) | |
694 | { | |
695 | struct klp_patch *patch = | |
696 | container_of(work, struct klp_patch, free_work); | |
697 | ||
698 | klp_free_patch_finish(patch); | |
b700e7f0 SJ |
699 | } |
700 | ||
7e35e4eb PM |
701 | void klp_free_patch_async(struct klp_patch *patch) |
702 | { | |
703 | klp_free_patch_start(patch); | |
704 | schedule_work(&patch->free_work); | |
705 | } | |
706 | ||
707 | void klp_free_replaced_patches_async(struct klp_patch *new_patch) | |
708 | { | |
709 | struct klp_patch *old_patch, *tmp_patch; | |
710 | ||
711 | klp_for_each_patch_safe(old_patch, tmp_patch) { | |
712 | if (old_patch == new_patch) | |
713 | return; | |
714 | klp_free_patch_async(old_patch); | |
715 | } | |
716 | } | |
717 | ||
b700e7f0 SJ |
718 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) |
719 | { | |
e1452b60 JB |
720 | if (!func->old_name) |
721 | return -EINVAL; | |
722 | ||
723 | /* | |
724 | * NOPs get the address later. The patched module must be loaded, | |
725 | * see klp_init_object_loaded(). | |
726 | */ | |
727 | if (!func->new_func && !func->nop) | |
f09d9086 MB |
728 | return -EINVAL; |
729 | ||
6e9df95b KB |
730 | if (strlen(func->old_name) >= KSYM_NAME_LEN) |
731 | return -EINVAL; | |
732 | ||
3c33f5b9 | 733 | INIT_LIST_HEAD(&func->stack_node); |
0dade9f3 | 734 | func->patched = false; |
d83a7cb3 | 735 | func->transition = false; |
b700e7f0 | 736 | |
444f9e99 CA |
737 | /* The format for the sysfs directory is <function,sympos> where sympos |
738 | * is the nth occurrence of this symbol in kallsyms for the patched | |
739 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
740 | * since a unique symbol will be the first occurrence. | |
741 | */ | |
4d141ab3 PM |
742 | return kobject_add(&func->kobj, &obj->kobj, "%s,%lu", |
743 | func->old_name, | |
744 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
745 | } |
746 | ||
a4ae16f6 SZ |
747 | static int klp_apply_object_relocs(struct klp_patch *patch, |
748 | struct klp_object *obj) | |
7c8e2bdd JP |
749 | { |
750 | int i, ret; | |
751 | struct klp_modinfo *info = patch->mod->klp_info; | |
752 | ||
753 | for (i = 1; i < info->hdr.e_shnum; i++) { | |
754 | Elf_Shdr *sec = info->sechdrs + i; | |
755 | ||
756 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
757 | continue; | |
758 | ||
759 | ret = klp_apply_section_relocs(patch->mod, info->sechdrs, | |
760 | info->secstrings, | |
761 | patch->mod->core_kallsyms.strtab, | |
762 | info->symndx, i, obj->name); | |
763 | if (ret) | |
764 | return ret; | |
765 | } | |
766 | ||
767 | return 0; | |
768 | } | |
769 | ||
b700e7f0 SJ |
770 | /* parts of the initialization that is done only when the object is loaded */ |
771 | static int klp_init_object_loaded(struct klp_patch *patch, | |
772 | struct klp_object *obj) | |
773 | { | |
774 | struct klp_func *func; | |
775 | int ret; | |
776 | ||
7c8e2bdd JP |
777 | if (klp_is_module(obj)) { |
778 | /* | |
779 | * Only write module-specific relocations here | |
780 | * (.klp.rela.{module}.*). vmlinux-specific relocations were | |
781 | * written earlier during the initialization of the klp module | |
782 | * itself. | |
783 | */ | |
784 | ret = klp_apply_object_relocs(patch, obj); | |
1d05334d PZ |
785 | if (ret) |
786 | return ret; | |
787 | } | |
9f255b63 | 788 | |
8cdd043a | 789 | klp_for_each_func(obj, func) { |
b2b018ef CA |
790 | ret = klp_find_object_symbol(obj->name, func->old_name, |
791 | func->old_sympos, | |
19514910 | 792 | (unsigned long *)&func->old_func); |
b700e7f0 SJ |
793 | if (ret) |
794 | return ret; | |
f5e547f4 | 795 | |
19514910 | 796 | ret = kallsyms_lookup_size_offset((unsigned long)func->old_func, |
f5e547f4 JP |
797 | &func->old_size, NULL); |
798 | if (!ret) { | |
799 | pr_err("kallsyms size lookup failed for '%s'\n", | |
800 | func->old_name); | |
801 | return -ENOENT; | |
802 | } | |
803 | ||
e1452b60 JB |
804 | if (func->nop) |
805 | func->new_func = func->old_func; | |
806 | ||
f5e547f4 JP |
807 | ret = kallsyms_lookup_size_offset((unsigned long)func->new_func, |
808 | &func->new_size, NULL); | |
809 | if (!ret) { | |
810 | pr_err("kallsyms size lookup failed for '%s' replacement\n", | |
811 | func->old_name); | |
812 | return -ENOENT; | |
813 | } | |
b700e7f0 SJ |
814 | } |
815 | ||
816 | return 0; | |
817 | } | |
818 | ||
819 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
820 | { | |
821 | struct klp_func *func; | |
822 | int ret; | |
823 | const char *name; | |
824 | ||
6e9df95b KB |
825 | if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN) |
826 | return -EINVAL; | |
827 | ||
0dade9f3 | 828 | obj->patched = false; |
8cb2c2dc | 829 | obj->mod = NULL; |
b700e7f0 SJ |
830 | |
831 | klp_find_object_module(obj); | |
832 | ||
833 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
4d141ab3 | 834 | ret = kobject_add(&obj->kobj, &patch->kobj, "%s", name); |
cad706df MB |
835 | if (ret) |
836 | return ret; | |
b700e7f0 | 837 | |
8cdd043a | 838 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
839 | ret = klp_init_func(obj, func); |
840 | if (ret) | |
0430f78b | 841 | return ret; |
b700e7f0 SJ |
842 | } |
843 | ||
0430f78b | 844 | if (klp_is_object_loaded(obj)) |
b700e7f0 | 845 | ret = klp_init_object_loaded(patch, obj); |
b700e7f0 | 846 | |
b700e7f0 SJ |
847 | return ret; |
848 | } | |
849 | ||
f68d67cf PM |
850 | static void klp_init_func_early(struct klp_object *obj, |
851 | struct klp_func *func) | |
852 | { | |
853 | kobject_init(&func->kobj, &klp_ktype_func); | |
854 | list_add_tail(&func->node, &obj->func_list); | |
855 | } | |
856 | ||
857 | static void klp_init_object_early(struct klp_patch *patch, | |
858 | struct klp_object *obj) | |
859 | { | |
860 | INIT_LIST_HEAD(&obj->func_list); | |
861 | kobject_init(&obj->kobj, &klp_ktype_object); | |
862 | list_add_tail(&obj->node, &patch->obj_list); | |
863 | } | |
864 | ||
5ef3dd20 | 865 | static void klp_init_patch_early(struct klp_patch *patch) |
b700e7f0 SJ |
866 | { |
867 | struct klp_object *obj; | |
0430f78b | 868 | struct klp_func *func; |
b700e7f0 | 869 | |
0430f78b | 870 | INIT_LIST_HEAD(&patch->list); |
20e55025 | 871 | INIT_LIST_HEAD(&patch->obj_list); |
4d141ab3 | 872 | kobject_init(&patch->kobj, &klp_ktype_patch); |
0dade9f3 | 873 | patch->enabled = false; |
68007289 | 874 | patch->forced = false; |
958ef1e3 | 875 | INIT_WORK(&patch->free_work, klp_free_patch_work_fn); |
3ec24776 | 876 | init_completion(&patch->finish); |
b700e7f0 | 877 | |
20e55025 | 878 | klp_for_each_object_static(patch, obj) { |
f68d67cf | 879 | klp_init_object_early(patch, obj); |
0430f78b | 880 | |
20e55025 | 881 | klp_for_each_func_static(obj, func) { |
f68d67cf | 882 | klp_init_func_early(obj, func); |
20e55025 | 883 | } |
0430f78b | 884 | } |
0430f78b PM |
885 | } |
886 | ||
887 | static int klp_init_patch(struct klp_patch *patch) | |
888 | { | |
889 | struct klp_object *obj; | |
890 | int ret; | |
891 | ||
4d141ab3 | 892 | ret = kobject_add(&patch->kobj, klp_root_kobj, "%s", patch->mod->name); |
958ef1e3 | 893 | if (ret) |
3ec24776 | 894 | return ret; |
b700e7f0 | 895 | |
e1452b60 JB |
896 | if (patch->replace) { |
897 | ret = klp_add_nops(patch); | |
898 | if (ret) | |
899 | return ret; | |
900 | } | |
901 | ||
8cdd043a | 902 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
903 | ret = klp_init_object(patch, obj); |
904 | if (ret) | |
958ef1e3 | 905 | return ret; |
b700e7f0 SJ |
906 | } |
907 | ||
99590ba5 | 908 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 | 909 | |
3ec24776 | 910 | return 0; |
b700e7f0 | 911 | } |
b700e7f0 | 912 | |
26c3e98e PM |
913 | static int __klp_disable_patch(struct klp_patch *patch) |
914 | { | |
915 | struct klp_object *obj; | |
916 | ||
917 | if (WARN_ON(!patch->enabled)) | |
918 | return -EINVAL; | |
919 | ||
920 | if (klp_transition_patch) | |
921 | return -EBUSY; | |
922 | ||
26c3e98e PM |
923 | klp_init_transition(patch, KLP_UNPATCHED); |
924 | ||
925 | klp_for_each_object(patch, obj) | |
926 | if (obj->patched) | |
927 | klp_pre_unpatch_callback(obj); | |
928 | ||
929 | /* | |
930 | * Enforce the order of the func->transition writes in | |
931 | * klp_init_transition() and the TIF_PATCH_PENDING writes in | |
932 | * klp_start_transition(). In the rare case where klp_ftrace_handler() | |
933 | * is called shortly after klp_update_patch_state() switches the task, | |
934 | * this ensures the handler sees that func->transition is set. | |
935 | */ | |
936 | smp_wmb(); | |
937 | ||
938 | klp_start_transition(); | |
26c3e98e | 939 | patch->enabled = false; |
958ef1e3 | 940 | klp_try_complete_transition(); |
26c3e98e PM |
941 | |
942 | return 0; | |
943 | } | |
944 | ||
26c3e98e PM |
945 | static int __klp_enable_patch(struct klp_patch *patch) |
946 | { | |
947 | struct klp_object *obj; | |
948 | int ret; | |
949 | ||
950 | if (klp_transition_patch) | |
951 | return -EBUSY; | |
952 | ||
953 | if (WARN_ON(patch->enabled)) | |
954 | return -EINVAL; | |
955 | ||
26c3e98e PM |
956 | pr_notice("enabling patch '%s'\n", patch->mod->name); |
957 | ||
958 | klp_init_transition(patch, KLP_PATCHED); | |
959 | ||
960 | /* | |
961 | * Enforce the order of the func->transition writes in | |
962 | * klp_init_transition() and the ops->func_stack writes in | |
963 | * klp_patch_object(), so that klp_ftrace_handler() will see the | |
964 | * func->transition updates before the handler is registered and the | |
965 | * new funcs become visible to the handler. | |
966 | */ | |
967 | smp_wmb(); | |
968 | ||
969 | klp_for_each_object(patch, obj) { | |
970 | if (!klp_is_object_loaded(obj)) | |
971 | continue; | |
972 | ||
973 | ret = klp_pre_patch_callback(obj); | |
974 | if (ret) { | |
975 | pr_warn("pre-patch callback failed for object '%s'\n", | |
976 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
977 | goto err; | |
978 | } | |
979 | ||
980 | ret = klp_patch_object(obj); | |
981 | if (ret) { | |
982 | pr_warn("failed to patch object '%s'\n", | |
983 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
984 | goto err; | |
985 | } | |
986 | } | |
987 | ||
988 | klp_start_transition(); | |
26c3e98e | 989 | patch->enabled = true; |
958ef1e3 | 990 | klp_try_complete_transition(); |
26c3e98e PM |
991 | |
992 | return 0; | |
993 | err: | |
994 | pr_warn("failed to enable patch '%s'\n", patch->mod->name); | |
995 | ||
996 | klp_cancel_transition(); | |
997 | return ret; | |
998 | } | |
999 | ||
1000 | /** | |
958ef1e3 PM |
1001 | * klp_enable_patch() - enable the livepatch |
1002 | * @patch: patch to be enabled | |
26c3e98e | 1003 | * |
958ef1e3 PM |
1004 | * Initializes the data structure associated with the patch, creates the sysfs |
1005 | * interface, performs the needed symbol lookups and code relocations, | |
1006 | * registers the patched functions with ftrace. | |
1007 | * | |
1008 | * This function is supposed to be called from the livepatch module_init() | |
1009 | * callback. | |
26c3e98e PM |
1010 | * |
1011 | * Return: 0 on success, otherwise error | |
1012 | */ | |
1013 | int klp_enable_patch(struct klp_patch *patch) | |
1014 | { | |
1015 | int ret; | |
5ef3dd20 | 1016 | struct klp_object *obj; |
26c3e98e | 1017 | |
5ef3dd20 | 1018 | if (!patch || !patch->mod || !patch->objs) |
958ef1e3 PM |
1019 | return -EINVAL; |
1020 | ||
5ef3dd20 DV |
1021 | klp_for_each_object_static(patch, obj) { |
1022 | if (!obj->funcs) | |
1023 | return -EINVAL; | |
1024 | } | |
1025 | ||
1026 | ||
958ef1e3 PM |
1027 | if (!is_livepatch_module(patch->mod)) { |
1028 | pr_err("module %s is not marked as a livepatch module\n", | |
1029 | patch->mod->name); | |
1030 | return -EINVAL; | |
1031 | } | |
1032 | ||
1033 | if (!klp_initialized()) | |
1034 | return -ENODEV; | |
1035 | ||
1036 | if (!klp_have_reliable_stack()) { | |
31adf230 PM |
1037 | pr_warn("This architecture doesn't have support for the livepatch consistency model.\n"); |
1038 | pr_warn("The livepatch transition may never complete.\n"); | |
958ef1e3 PM |
1039 | } |
1040 | ||
26c3e98e PM |
1041 | mutex_lock(&klp_mutex); |
1042 | ||
92c9abf5 PM |
1043 | if (!klp_is_patch_compatible(patch)) { |
1044 | pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n", | |
1045 | patch->mod->name); | |
1046 | mutex_unlock(&klp_mutex); | |
1047 | return -EINVAL; | |
1048 | } | |
1049 | ||
5ef3dd20 DV |
1050 | if (!try_module_get(patch->mod)) |
1051 | return -ENODEV; | |
1052 | ||
1053 | klp_init_patch_early(patch); | |
26c3e98e | 1054 | |
958ef1e3 PM |
1055 | ret = klp_init_patch(patch); |
1056 | if (ret) | |
1057 | goto err; | |
1058 | ||
26c3e98e | 1059 | ret = __klp_enable_patch(patch); |
958ef1e3 PM |
1060 | if (ret) |
1061 | goto err; | |
1062 | ||
1063 | mutex_unlock(&klp_mutex); | |
1064 | ||
1065 | return 0; | |
26c3e98e PM |
1066 | |
1067 | err: | |
958ef1e3 PM |
1068 | klp_free_patch_start(patch); |
1069 | ||
26c3e98e | 1070 | mutex_unlock(&klp_mutex); |
958ef1e3 PM |
1071 | |
1072 | klp_free_patch_finish(patch); | |
1073 | ||
26c3e98e PM |
1074 | return ret; |
1075 | } | |
1076 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
1077 | ||
e1452b60 | 1078 | /* |
7e35e4eb | 1079 | * This function unpatches objects from the replaced livepatches. |
e1452b60 JB |
1080 | * |
1081 | * We could be pretty aggressive here. It is called in the situation where | |
7e35e4eb PM |
1082 | * these structures are no longer accessed from the ftrace handler. |
1083 | * All functions are redirected by the klp_transition_patch. They | |
1084 | * use either a new code or they are in the original code because | |
1085 | * of the special nop function patches. | |
e1452b60 JB |
1086 | * |
1087 | * The only exception is when the transition was forced. In this case, | |
1088 | * klp_ftrace_handler() might still see the replaced patch on the stack. | |
1089 | * Fortunately, it is carefully designed to work with removed functions | |
1090 | * thanks to RCU. We only have to keep the patches on the system. Also | |
1091 | * this is handled transparently by patch->module_put. | |
1092 | */ | |
7e35e4eb | 1093 | void klp_unpatch_replaced_patches(struct klp_patch *new_patch) |
e1452b60 | 1094 | { |
7e35e4eb | 1095 | struct klp_patch *old_patch; |
e1452b60 | 1096 | |
7e35e4eb | 1097 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
1098 | if (old_patch == new_patch) |
1099 | return; | |
1100 | ||
1101 | old_patch->enabled = false; | |
1102 | klp_unpatch_objects(old_patch); | |
e1452b60 JB |
1103 | } |
1104 | } | |
1105 | ||
d697bad5 PM |
1106 | /* |
1107 | * This function removes the dynamically allocated 'nop' functions. | |
1108 | * | |
1109 | * We could be pretty aggressive. NOPs do not change the existing | |
1110 | * behavior except for adding unnecessary delay by the ftrace handler. | |
1111 | * | |
1112 | * It is safe even when the transition was forced. The ftrace handler | |
1113 | * will see a valid ops->func_stack entry thanks to RCU. | |
1114 | * | |
1115 | * We could even free the NOPs structures. They must be the last entry | |
1116 | * in ops->func_stack. Therefore unregister_ftrace_function() is called. | |
1117 | * It does the same as klp_synchronize_transition() to make sure that | |
1118 | * nobody is inside the ftrace handler once the operation finishes. | |
1119 | * | |
1120 | * IMPORTANT: It must be called right after removing the replaced patches! | |
1121 | */ | |
1122 | void klp_discard_nops(struct klp_patch *new_patch) | |
1123 | { | |
1124 | klp_unpatch_objects_dynamic(klp_transition_patch); | |
1125 | klp_free_objects_dynamic(klp_transition_patch); | |
1126 | } | |
1127 | ||
ef8daf8e JL |
1128 | /* |
1129 | * Remove parts of patches that touch a given kernel module. The list of | |
1130 | * patches processed might be limited. When limit is NULL, all patches | |
1131 | * will be handled. | |
1132 | */ | |
1133 | static void klp_cleanup_module_patches_limited(struct module *mod, | |
1134 | struct klp_patch *limit) | |
1135 | { | |
1136 | struct klp_patch *patch; | |
1137 | struct klp_object *obj; | |
1138 | ||
ecba29f4 | 1139 | klp_for_each_patch(patch) { |
ef8daf8e JL |
1140 | if (patch == limit) |
1141 | break; | |
1142 | ||
1143 | klp_for_each_object(patch, obj) { | |
1144 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1145 | continue; | |
1146 | ||
a087cdd4 PM |
1147 | if (patch != klp_transition_patch) |
1148 | klp_pre_unpatch_callback(obj); | |
fc41efc1 | 1149 | |
a087cdd4 PM |
1150 | pr_notice("reverting patch '%s' on unloading module '%s'\n", |
1151 | patch->mod->name, obj->mod->name); | |
1152 | klp_unpatch_object(obj); | |
fc41efc1 | 1153 | |
a087cdd4 | 1154 | klp_post_unpatch_callback(obj); |
ef8daf8e JL |
1155 | |
1156 | klp_free_object_loaded(obj); | |
1157 | break; | |
1158 | } | |
1159 | } | |
1160 | } | |
1161 | ||
7e545d6e | 1162 | int klp_module_coming(struct module *mod) |
b700e7f0 | 1163 | { |
b700e7f0 | 1164 | int ret; |
7e545d6e JY |
1165 | struct klp_patch *patch; |
1166 | struct klp_object *obj; | |
b700e7f0 | 1167 | |
7e545d6e JY |
1168 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
1169 | return -EINVAL; | |
b700e7f0 | 1170 | |
dcf550e5 JP |
1171 | if (!strcmp(mod->name, "vmlinux")) { |
1172 | pr_err("vmlinux.ko: invalid module name"); | |
1173 | return -EINVAL; | |
1174 | } | |
1175 | ||
7e545d6e JY |
1176 | mutex_lock(&klp_mutex); |
1177 | /* | |
1178 | * Each module has to know that klp_module_coming() | |
1179 | * has been called. We never know what module will | |
1180 | * get patched by a new patch. | |
1181 | */ | |
1182 | mod->klp_alive = true; | |
b700e7f0 | 1183 | |
ecba29f4 | 1184 | klp_for_each_patch(patch) { |
7e545d6e JY |
1185 | klp_for_each_object(patch, obj) { |
1186 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1187 | continue; | |
b700e7f0 | 1188 | |
7e545d6e | 1189 | obj->mod = mod; |
b700e7f0 | 1190 | |
7e545d6e JY |
1191 | ret = klp_init_object_loaded(patch, obj); |
1192 | if (ret) { | |
1193 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
1194 | patch->mod->name, obj->mod->name, ret); | |
1195 | goto err; | |
1196 | } | |
b700e7f0 | 1197 | |
7e545d6e JY |
1198 | pr_notice("applying patch '%s' to loading module '%s'\n", |
1199 | patch->mod->name, obj->mod->name); | |
1200 | ||
93862e38 JL |
1201 | ret = klp_pre_patch_callback(obj); |
1202 | if (ret) { | |
1203 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1204 | obj->name); | |
1205 | goto err; | |
1206 | } | |
1207 | ||
0dade9f3 | 1208 | ret = klp_patch_object(obj); |
7e545d6e JY |
1209 | if (ret) { |
1210 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
1211 | patch->mod->name, obj->mod->name, ret); | |
93862e38 | 1212 | |
5aaf1ab5 | 1213 | klp_post_unpatch_callback(obj); |
7e545d6e JY |
1214 | goto err; |
1215 | } | |
1216 | ||
93862e38 JL |
1217 | if (patch != klp_transition_patch) |
1218 | klp_post_patch_callback(obj); | |
1219 | ||
7e545d6e JY |
1220 | break; |
1221 | } | |
1222 | } | |
b700e7f0 | 1223 | |
7e545d6e | 1224 | mutex_unlock(&klp_mutex); |
b700e7f0 | 1225 | |
7e545d6e | 1226 | return 0; |
b700e7f0 | 1227 | |
7e545d6e JY |
1228 | err: |
1229 | /* | |
1230 | * If a patch is unsuccessfully applied, return | |
1231 | * error to the module loader. | |
1232 | */ | |
1233 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
1234 | patch->mod->name, obj->mod->name, obj->mod->name); | |
1235 | mod->klp_alive = false; | |
4ff96fb5 | 1236 | obj->mod = NULL; |
ef8daf8e | 1237 | klp_cleanup_module_patches_limited(mod, patch); |
7e545d6e JY |
1238 | mutex_unlock(&klp_mutex); |
1239 | ||
1240 | return ret; | |
b700e7f0 SJ |
1241 | } |
1242 | ||
7e545d6e | 1243 | void klp_module_going(struct module *mod) |
b700e7f0 | 1244 | { |
7e545d6e JY |
1245 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1246 | mod->state != MODULE_STATE_COMING)) | |
1247 | return; | |
b700e7f0 SJ |
1248 | |
1249 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1250 | /* |
7e545d6e JY |
1251 | * Each module has to know that klp_module_going() |
1252 | * has been called. We never know what module will | |
1253 | * get patched by a new patch. | |
8cb2c2dc | 1254 | */ |
7e545d6e | 1255 | mod->klp_alive = false; |
8cb2c2dc | 1256 | |
ef8daf8e | 1257 | klp_cleanup_module_patches_limited(mod, NULL); |
b700e7f0 SJ |
1258 | |
1259 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1260 | } |
1261 | ||
26029d88 | 1262 | static int __init klp_init(void) |
b700e7f0 | 1263 | { |
b700e7f0 | 1264 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1265 | if (!klp_root_kobj) |
1266 | return -ENOMEM; | |
b700e7f0 SJ |
1267 | |
1268 | return 0; | |
b700e7f0 SJ |
1269 | } |
1270 | ||
1271 | module_init(klp_init); |