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 | ||
4f1354d5 | 128 | static int klp_match_callback(void *data, unsigned long addr) |
b700e7f0 SJ |
129 | { |
130 | struct klp_find_arg *args = data; | |
131 | ||
b700e7f0 SJ |
132 | args->addr = addr; |
133 | args->count++; | |
134 | ||
b2b018ef CA |
135 | /* |
136 | * Finish the search when the symbol is found for the desired position | |
137 | * or the position is not defined for a non-unique symbol. | |
138 | */ | |
139 | if ((args->pos && (args->count == args->pos)) || | |
140 | (!args->pos && (args->count > 1))) | |
141 | return 1; | |
142 | ||
b700e7f0 SJ |
143 | return 0; |
144 | } | |
145 | ||
4f1354d5 ZL |
146 | static int klp_find_callback(void *data, const char *name, |
147 | struct module *mod, unsigned long addr) | |
9cb37357 ZL |
148 | { |
149 | struct klp_find_arg *args = data; | |
150 | ||
4f1354d5 ZL |
151 | if ((mod && !args->objname) || (!mod && args->objname)) |
152 | return 0; | |
9cb37357 | 153 | |
4f1354d5 ZL |
154 | if (strcmp(args->name, name)) |
155 | return 0; | |
9cb37357 | 156 | |
4f1354d5 ZL |
157 | if (args->objname && strcmp(args->objname, mod->name)) |
158 | return 0; | |
159 | ||
160 | return klp_match_callback(data, addr); | |
9cb37357 ZL |
161 | } |
162 | ||
b700e7f0 | 163 | static int klp_find_object_symbol(const char *objname, const char *name, |
b2b018ef | 164 | unsigned long sympos, unsigned long *addr) |
b700e7f0 SJ |
165 | { |
166 | struct klp_find_arg args = { | |
167 | .objname = objname, | |
168 | .name = name, | |
169 | .addr = 0, | |
b2b018ef CA |
170 | .count = 0, |
171 | .pos = sympos, | |
b700e7f0 SJ |
172 | }; |
173 | ||
72f04b50 ZC |
174 | if (objname) |
175 | module_kallsyms_on_each_symbol(klp_find_callback, &args); | |
176 | else | |
9cb37357 | 177 | kallsyms_on_each_match_symbol(klp_match_callback, name, &args); |
b700e7f0 | 178 | |
b2b018ef CA |
179 | /* |
180 | * Ensure an address was found. If sympos is 0, ensure symbol is unique; | |
181 | * otherwise ensure the symbol position count matches sympos. | |
182 | */ | |
183 | if (args.addr == 0) | |
b700e7f0 | 184 | pr_err("symbol '%s' not found in symbol table\n", name); |
b2b018ef | 185 | else if (args.count > 1 && sympos == 0) { |
f995b5f7 PM |
186 | pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n", |
187 | name, objname); | |
b2b018ef CA |
188 | } else if (sympos != args.count && sympos > 0) { |
189 | pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n", | |
190 | sympos, name, objname ? objname : "vmlinux"); | |
191 | } else { | |
b700e7f0 SJ |
192 | *addr = args.addr; |
193 | return 0; | |
194 | } | |
195 | ||
196 | *addr = 0; | |
197 | return -EINVAL; | |
198 | } | |
199 | ||
2f293651 | 200 | static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, |
ca376a93 JP |
201 | unsigned int symndx, Elf_Shdr *relasec, |
202 | const char *sec_objname) | |
b700e7f0 | 203 | { |
ca376a93 JP |
204 | int i, cnt, ret; |
205 | char sym_objname[MODULE_NAME_LEN]; | |
206 | char sym_name[KSYM_NAME_LEN]; | |
425595a7 JY |
207 | Elf_Rela *relas; |
208 | Elf_Sym *sym; | |
209 | unsigned long sympos, addr; | |
ca376a93 JP |
210 | bool sym_vmlinux; |
211 | bool sec_vmlinux = !strcmp(sec_objname, "vmlinux"); | |
b700e7f0 | 212 | |
b2b018ef | 213 | /* |
ca376a93 | 214 | * Since the field widths for sym_objname and sym_name in the sscanf() |
425595a7 JY |
215 | * call are hard-coded and correspond to MODULE_NAME_LEN and |
216 | * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN | |
217 | * and KSYM_NAME_LEN have the values we expect them to have. | |
218 | * | |
219 | * Because the value of MODULE_NAME_LEN can differ among architectures, | |
220 | * we use the smallest/strictest upper bound possible (56, based on | |
221 | * the current definition of MODULE_NAME_LEN) to prevent overflows. | |
b2b018ef | 222 | */ |
b8a94bfb | 223 | BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512); |
425595a7 JY |
224 | |
225 | relas = (Elf_Rela *) relasec->sh_addr; | |
226 | /* For each rela in this klp relocation section */ | |
227 | for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { | |
2f293651 | 228 | sym = (Elf_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info); |
425595a7 | 229 | if (sym->st_shndx != SHN_LIVEPATCH) { |
77f8f39a | 230 | pr_err("symbol %s is not marked as a livepatch symbol\n", |
425595a7 JY |
231 | strtab + sym->st_name); |
232 | return -EINVAL; | |
233 | } | |
234 | ||
ca376a93 | 235 | /* Format: .klp.sym.sym_objname.sym_name,sympos */ |
425595a7 | 236 | cnt = sscanf(strtab + sym->st_name, |
b8a94bfb | 237 | ".klp.sym.%55[^.].%511[^,],%lu", |
ca376a93 | 238 | sym_objname, sym_name, &sympos); |
425595a7 | 239 | if (cnt != 3) { |
77f8f39a | 240 | pr_err("symbol %s has an incorrectly formatted name\n", |
425595a7 JY |
241 | strtab + sym->st_name); |
242 | return -EINVAL; | |
243 | } | |
244 | ||
ca376a93 JP |
245 | sym_vmlinux = !strcmp(sym_objname, "vmlinux"); |
246 | ||
247 | /* | |
248 | * Prevent module-specific KLP rela sections from referencing | |
249 | * vmlinux symbols. This helps prevent ordering issues with | |
250 | * module special section initializations. Presumably such | |
251 | * symbols are exported and normal relas can be used instead. | |
252 | */ | |
253 | if (!sec_vmlinux && sym_vmlinux) { | |
254 | pr_err("invalid access to vmlinux symbol '%s' from module-specific livepatch relocation section", | |
255 | sym_name); | |
256 | return -EINVAL; | |
257 | } | |
258 | ||
425595a7 | 259 | /* klp_find_object_symbol() treats a NULL objname as vmlinux */ |
ca376a93 JP |
260 | ret = klp_find_object_symbol(sym_vmlinux ? NULL : sym_objname, |
261 | sym_name, sympos, &addr); | |
425595a7 JY |
262 | if (ret) |
263 | return ret; | |
264 | ||
265 | sym->st_value = addr; | |
266 | } | |
267 | ||
268 | return 0; | |
b700e7f0 SJ |
269 | } |
270 | ||
7c8e2bdd JP |
271 | /* |
272 | * At a high-level, there are two types of klp relocation sections: those which | |
273 | * reference symbols which live in vmlinux; and those which reference symbols | |
274 | * which live in other modules. This function is called for both types: | |
275 | * | |
276 | * 1) When a klp module itself loads, the module code calls this function to | |
277 | * write vmlinux-specific klp relocations (.klp.rela.vmlinux.* sections). | |
278 | * These relocations are written to the klp module text to allow the patched | |
279 | * code/data to reference unexported vmlinux symbols. They're written as | |
280 | * early as possible to ensure that other module init code (.e.g., | |
281 | * jump_label_apply_nops) can access any unexported vmlinux symbols which | |
282 | * might be referenced by the klp module's special sections. | |
283 | * | |
284 | * 2) When a to-be-patched module loads -- or is already loaded when a | |
285 | * corresponding klp module loads -- klp code calls this function to write | |
286 | * module-specific klp relocations (.klp.rela.{module}.* sections). These | |
287 | * are written to the klp module text to allow the patched code/data to | |
288 | * reference symbols which live in the to-be-patched module or one of its | |
289 | * module dependencies. Exported symbols are supported, in addition to | |
290 | * unexported symbols, in order to enable late module patching, which allows | |
291 | * the to-be-patched module to be loaded and patched sometime *after* the | |
292 | * klp module is loaded. | |
293 | */ | |
294 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, | |
295 | const char *shstrtab, const char *strtab, | |
296 | unsigned int symndx, unsigned int secndx, | |
297 | const char *objname) | |
b700e7f0 | 298 | { |
7c8e2bdd | 299 | int cnt, ret; |
425595a7 | 300 | char sec_objname[MODULE_NAME_LEN]; |
7c8e2bdd | 301 | Elf_Shdr *sec = sechdrs + secndx; |
b700e7f0 | 302 | |
7c8e2bdd JP |
303 | /* |
304 | * Format: .klp.rela.sec_objname.section_name | |
305 | * See comment in klp_resolve_symbols() for an explanation | |
306 | * of the selected field width value. | |
307 | */ | |
308 | cnt = sscanf(shstrtab + sec->sh_name, ".klp.rela.%55[^.]", | |
309 | sec_objname); | |
310 | if (cnt != 1) { | |
311 | pr_err("section %s has an incorrectly formatted name\n", | |
312 | shstrtab + sec->sh_name); | |
b700e7f0 | 313 | return -EINVAL; |
7c8e2bdd | 314 | } |
b700e7f0 | 315 | |
7c8e2bdd JP |
316 | if (strcmp(objname ? objname : "vmlinux", sec_objname)) |
317 | return 0; | |
064c89df | 318 | |
ca376a93 | 319 | ret = klp_resolve_symbols(sechdrs, strtab, symndx, sec, sec_objname); |
7c8e2bdd JP |
320 | if (ret) |
321 | return ret; | |
b700e7f0 | 322 | |
7c8e2bdd | 323 | return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); |
b700e7f0 SJ |
324 | } |
325 | ||
b700e7f0 SJ |
326 | /* |
327 | * Sysfs Interface | |
328 | * | |
329 | * /sys/kernel/livepatch | |
330 | * /sys/kernel/livepatch/<patch> | |
331 | * /sys/kernel/livepatch/<patch>/enabled | |
d83a7cb3 | 332 | * /sys/kernel/livepatch/<patch>/transition |
c99a2be7 | 333 | * /sys/kernel/livepatch/<patch>/force |
b700e7f0 | 334 | * /sys/kernel/livepatch/<patch>/<object> |
bb26cfd9 | 335 | * /sys/kernel/livepatch/<patch>/<object>/patched |
444f9e99 | 336 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 | 337 | */ |
26c3e98e | 338 | static int __klp_disable_patch(struct klp_patch *patch); |
b700e7f0 SJ |
339 | |
340 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
341 | const char *buf, size_t count) | |
342 | { | |
343 | struct klp_patch *patch; | |
344 | int ret; | |
68ae4b2b | 345 | bool enabled; |
b700e7f0 | 346 | |
68ae4b2b | 347 | ret = kstrtobool(buf, &enabled); |
b700e7f0 | 348 | if (ret) |
68ae4b2b | 349 | return ret; |
b700e7f0 SJ |
350 | |
351 | patch = container_of(kobj, struct klp_patch, kobj); | |
352 | ||
353 | mutex_lock(&klp_mutex); | |
354 | ||
68ae4b2b | 355 | if (patch->enabled == enabled) { |
b700e7f0 SJ |
356 | /* already in requested state */ |
357 | ret = -EINVAL; | |
958ef1e3 | 358 | goto out; |
b700e7f0 SJ |
359 | } |
360 | ||
958ef1e3 PM |
361 | /* |
362 | * Allow to reverse a pending transition in both ways. It might be | |
363 | * necessary to complete the transition without forcing and breaking | |
364 | * the system integrity. | |
365 | * | |
366 | * Do not allow to re-enable a disabled patch. | |
367 | */ | |
368 | if (patch == klp_transition_patch) | |
d83a7cb3 | 369 | klp_reverse_transition(); |
958ef1e3 | 370 | else if (!enabled) |
b700e7f0 | 371 | ret = __klp_disable_patch(patch); |
958ef1e3 PM |
372 | else |
373 | ret = -EINVAL; | |
b700e7f0 | 374 | |
958ef1e3 | 375 | out: |
b700e7f0 SJ |
376 | mutex_unlock(&klp_mutex); |
377 | ||
958ef1e3 PM |
378 | if (ret) |
379 | return ret; | |
b700e7f0 | 380 | return count; |
b700e7f0 SJ |
381 | } |
382 | ||
383 | static ssize_t enabled_show(struct kobject *kobj, | |
384 | struct kobj_attribute *attr, char *buf) | |
385 | { | |
386 | struct klp_patch *patch; | |
387 | ||
388 | patch = container_of(kobj, struct klp_patch, kobj); | |
0dade9f3 | 389 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled); |
b700e7f0 SJ |
390 | } |
391 | ||
d83a7cb3 JP |
392 | static ssize_t transition_show(struct kobject *kobj, |
393 | struct kobj_attribute *attr, char *buf) | |
394 | { | |
395 | struct klp_patch *patch; | |
396 | ||
397 | patch = container_of(kobj, struct klp_patch, kobj); | |
398 | return snprintf(buf, PAGE_SIZE-1, "%d\n", | |
399 | patch == klp_transition_patch); | |
b700e7f0 SJ |
400 | } |
401 | ||
c99a2be7 MB |
402 | static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, |
403 | const char *buf, size_t count) | |
404 | { | |
405 | struct klp_patch *patch; | |
406 | int ret; | |
407 | bool val; | |
408 | ||
c99a2be7 MB |
409 | ret = kstrtobool(buf, &val); |
410 | if (ret) | |
411 | return ret; | |
412 | ||
8869016d MB |
413 | if (!val) |
414 | return count; | |
415 | ||
416 | mutex_lock(&klp_mutex); | |
417 | ||
418 | patch = container_of(kobj, struct klp_patch, kobj); | |
419 | if (patch != klp_transition_patch) { | |
420 | mutex_unlock(&klp_mutex); | |
421 | return -EINVAL; | |
422 | } | |
423 | ||
424 | klp_force_transition(); | |
425 | ||
426 | mutex_unlock(&klp_mutex); | |
c99a2be7 MB |
427 | |
428 | return count; | |
429 | } | |
430 | ||
b700e7f0 | 431 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); |
d83a7cb3 | 432 | static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); |
c99a2be7 | 433 | static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); |
b700e7f0 SJ |
434 | static struct attribute *klp_patch_attrs[] = { |
435 | &enabled_kobj_attr.attr, | |
d83a7cb3 | 436 | &transition_kobj_attr.attr, |
c99a2be7 | 437 | &force_kobj_attr.attr, |
b700e7f0 SJ |
438 | NULL |
439 | }; | |
70283454 | 440 | ATTRIBUTE_GROUPS(klp_patch); |
b700e7f0 | 441 | |
bb26cfd9 SL |
442 | static ssize_t patched_show(struct kobject *kobj, |
443 | struct kobj_attribute *attr, char *buf) | |
444 | { | |
445 | struct klp_object *obj; | |
446 | ||
447 | obj = container_of(kobj, struct klp_object, kobj); | |
448 | return sysfs_emit(buf, "%d\n", obj->patched); | |
449 | } | |
450 | ||
451 | static struct kobj_attribute patched_kobj_attr = __ATTR_RO(patched); | |
452 | static struct attribute *klp_object_attrs[] = { | |
453 | &patched_kobj_attr.attr, | |
454 | NULL, | |
455 | }; | |
456 | ATTRIBUTE_GROUPS(klp_object); | |
457 | ||
e1452b60 JB |
458 | static void klp_free_object_dynamic(struct klp_object *obj) |
459 | { | |
460 | kfree(obj->name); | |
461 | kfree(obj); | |
462 | } | |
463 | ||
f68d67cf PM |
464 | static void klp_init_func_early(struct klp_object *obj, |
465 | struct klp_func *func); | |
466 | static void klp_init_object_early(struct klp_patch *patch, | |
467 | struct klp_object *obj); | |
4d141ab3 | 468 | |
f68d67cf PM |
469 | static struct klp_object *klp_alloc_object_dynamic(const char *name, |
470 | struct klp_patch *patch) | |
e1452b60 JB |
471 | { |
472 | struct klp_object *obj; | |
473 | ||
474 | obj = kzalloc(sizeof(*obj), GFP_KERNEL); | |
475 | if (!obj) | |
476 | return NULL; | |
477 | ||
478 | if (name) { | |
479 | obj->name = kstrdup(name, GFP_KERNEL); | |
480 | if (!obj->name) { | |
481 | kfree(obj); | |
482 | return NULL; | |
483 | } | |
484 | } | |
485 | ||
f68d67cf | 486 | klp_init_object_early(patch, obj); |
e1452b60 JB |
487 | obj->dynamic = true; |
488 | ||
489 | return obj; | |
490 | } | |
491 | ||
492 | static void klp_free_func_nop(struct klp_func *func) | |
493 | { | |
494 | kfree(func->old_name); | |
495 | kfree(func); | |
496 | } | |
497 | ||
498 | static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func, | |
499 | struct klp_object *obj) | |
500 | { | |
501 | struct klp_func *func; | |
502 | ||
503 | func = kzalloc(sizeof(*func), GFP_KERNEL); | |
504 | if (!func) | |
505 | return NULL; | |
506 | ||
507 | if (old_func->old_name) { | |
508 | func->old_name = kstrdup(old_func->old_name, GFP_KERNEL); | |
509 | if (!func->old_name) { | |
510 | kfree(func); | |
511 | return NULL; | |
512 | } | |
513 | } | |
514 | ||
f68d67cf | 515 | klp_init_func_early(obj, func); |
e1452b60 JB |
516 | /* |
517 | * func->new_func is same as func->old_func. These addresses are | |
518 | * set when the object is loaded, see klp_init_object_loaded(). | |
519 | */ | |
520 | func->old_sympos = old_func->old_sympos; | |
521 | func->nop = true; | |
522 | ||
523 | return func; | |
524 | } | |
525 | ||
526 | static int klp_add_object_nops(struct klp_patch *patch, | |
527 | struct klp_object *old_obj) | |
528 | { | |
529 | struct klp_object *obj; | |
530 | struct klp_func *func, *old_func; | |
531 | ||
532 | obj = klp_find_object(patch, old_obj); | |
533 | ||
534 | if (!obj) { | |
f68d67cf | 535 | obj = klp_alloc_object_dynamic(old_obj->name, patch); |
e1452b60 JB |
536 | if (!obj) |
537 | return -ENOMEM; | |
e1452b60 JB |
538 | } |
539 | ||
540 | klp_for_each_func(old_obj, old_func) { | |
541 | func = klp_find_func(obj, old_func); | |
542 | if (func) | |
543 | continue; | |
544 | ||
545 | func = klp_alloc_func_nop(old_func, obj); | |
546 | if (!func) | |
547 | return -ENOMEM; | |
e1452b60 JB |
548 | } |
549 | ||
550 | return 0; | |
551 | } | |
552 | ||
553 | /* | |
554 | * Add 'nop' functions which simply return to the caller to run | |
555 | * the original function. The 'nop' functions are added to a | |
556 | * patch to facilitate a 'replace' mode. | |
557 | */ | |
558 | static int klp_add_nops(struct klp_patch *patch) | |
559 | { | |
560 | struct klp_patch *old_patch; | |
561 | struct klp_object *old_obj; | |
562 | ||
ecba29f4 | 563 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
564 | klp_for_each_object(old_patch, old_obj) { |
565 | int err; | |
566 | ||
567 | err = klp_add_object_nops(patch, old_obj); | |
568 | if (err) | |
569 | return err; | |
570 | } | |
571 | } | |
572 | ||
573 | return 0; | |
574 | } | |
575 | ||
b700e7f0 SJ |
576 | static void klp_kobj_release_patch(struct kobject *kobj) |
577 | { | |
3ec24776 JP |
578 | struct klp_patch *patch; |
579 | ||
580 | patch = container_of(kobj, struct klp_patch, kobj); | |
581 | complete(&patch->finish); | |
b700e7f0 SJ |
582 | } |
583 | ||
584 | static struct kobj_type klp_ktype_patch = { | |
585 | .release = klp_kobj_release_patch, | |
586 | .sysfs_ops = &kobj_sysfs_ops, | |
70283454 | 587 | .default_groups = klp_patch_groups, |
b700e7f0 SJ |
588 | }; |
589 | ||
cad706df MB |
590 | static void klp_kobj_release_object(struct kobject *kobj) |
591 | { | |
e1452b60 JB |
592 | struct klp_object *obj; |
593 | ||
594 | obj = container_of(kobj, struct klp_object, kobj); | |
595 | ||
596 | if (obj->dynamic) | |
597 | klp_free_object_dynamic(obj); | |
cad706df MB |
598 | } |
599 | ||
600 | static struct kobj_type klp_ktype_object = { | |
601 | .release = klp_kobj_release_object, | |
602 | .sysfs_ops = &kobj_sysfs_ops, | |
bb26cfd9 | 603 | .default_groups = klp_object_groups, |
cad706df MB |
604 | }; |
605 | ||
b700e7f0 SJ |
606 | static void klp_kobj_release_func(struct kobject *kobj) |
607 | { | |
e1452b60 JB |
608 | struct klp_func *func; |
609 | ||
610 | func = container_of(kobj, struct klp_func, kobj); | |
611 | ||
612 | if (func->nop) | |
613 | klp_free_func_nop(func); | |
b700e7f0 SJ |
614 | } |
615 | ||
616 | static struct kobj_type klp_ktype_func = { | |
617 | .release = klp_kobj_release_func, | |
618 | .sysfs_ops = &kobj_sysfs_ops, | |
619 | }; | |
620 | ||
d697bad5 | 621 | static void __klp_free_funcs(struct klp_object *obj, bool nops_only) |
b700e7f0 | 622 | { |
e1452b60 | 623 | struct klp_func *func, *tmp_func; |
b700e7f0 | 624 | |
e1452b60 | 625 | klp_for_each_func_safe(obj, func, tmp_func) { |
d697bad5 PM |
626 | if (nops_only && !func->nop) |
627 | continue; | |
628 | ||
629 | list_del(&func->node); | |
4d141ab3 | 630 | kobject_put(&func->kobj); |
0430f78b | 631 | } |
b700e7f0 SJ |
632 | } |
633 | ||
634 | /* Clean up when a patched object is unloaded */ | |
635 | static void klp_free_object_loaded(struct klp_object *obj) | |
636 | { | |
637 | struct klp_func *func; | |
638 | ||
639 | obj->mod = NULL; | |
640 | ||
e1452b60 | 641 | klp_for_each_func(obj, func) { |
19514910 | 642 | func->old_func = NULL; |
e1452b60 JB |
643 | |
644 | if (func->nop) | |
645 | func->new_func = NULL; | |
646 | } | |
b700e7f0 SJ |
647 | } |
648 | ||
d697bad5 | 649 | static void __klp_free_objects(struct klp_patch *patch, bool nops_only) |
b700e7f0 | 650 | { |
e1452b60 | 651 | struct klp_object *obj, *tmp_obj; |
b700e7f0 | 652 | |
e1452b60 | 653 | klp_for_each_object_safe(patch, obj, tmp_obj) { |
d697bad5 PM |
654 | __klp_free_funcs(obj, nops_only); |
655 | ||
656 | if (nops_only && !obj->dynamic) | |
657 | continue; | |
658 | ||
659 | list_del(&obj->node); | |
4d141ab3 | 660 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
661 | } |
662 | } | |
663 | ||
d697bad5 PM |
664 | static void klp_free_objects(struct klp_patch *patch) |
665 | { | |
666 | __klp_free_objects(patch, false); | |
667 | } | |
668 | ||
669 | static void klp_free_objects_dynamic(struct klp_patch *patch) | |
670 | { | |
671 | __klp_free_objects(patch, true); | |
672 | } | |
673 | ||
0430f78b PM |
674 | /* |
675 | * This function implements the free operations that can be called safely | |
676 | * under klp_mutex. | |
677 | * | |
678 | * The operation must be completed by calling klp_free_patch_finish() | |
679 | * outside klp_mutex. | |
680 | */ | |
7e35e4eb | 681 | static void klp_free_patch_start(struct klp_patch *patch) |
b700e7f0 | 682 | { |
b700e7f0 SJ |
683 | if (!list_empty(&patch->list)) |
684 | list_del(&patch->list); | |
0430f78b PM |
685 | |
686 | klp_free_objects(patch); | |
687 | } | |
688 | ||
689 | /* | |
690 | * This function implements the free part that must be called outside | |
691 | * klp_mutex. | |
692 | * | |
693 | * It must be called after klp_free_patch_start(). And it has to be | |
694 | * the last function accessing the livepatch structures when the patch | |
695 | * gets disabled. | |
696 | */ | |
697 | static void klp_free_patch_finish(struct klp_patch *patch) | |
698 | { | |
699 | /* | |
700 | * Avoid deadlock with enabled_store() sysfs callback by | |
701 | * calling this outside klp_mutex. It is safe because | |
702 | * this is called when the patch gets disabled and it | |
703 | * cannot get enabled again. | |
704 | */ | |
4d141ab3 PM |
705 | kobject_put(&patch->kobj); |
706 | wait_for_completion(&patch->finish); | |
958ef1e3 PM |
707 | |
708 | /* Put the module after the last access to struct klp_patch. */ | |
709 | if (!patch->forced) | |
710 | module_put(patch->mod); | |
711 | } | |
712 | ||
713 | /* | |
714 | * The livepatch might be freed from sysfs interface created by the patch. | |
715 | * This work allows to wait until the interface is destroyed in a separate | |
716 | * context. | |
717 | */ | |
718 | static void klp_free_patch_work_fn(struct work_struct *work) | |
719 | { | |
720 | struct klp_patch *patch = | |
721 | container_of(work, struct klp_patch, free_work); | |
722 | ||
723 | klp_free_patch_finish(patch); | |
b700e7f0 SJ |
724 | } |
725 | ||
7e35e4eb PM |
726 | void klp_free_patch_async(struct klp_patch *patch) |
727 | { | |
728 | klp_free_patch_start(patch); | |
729 | schedule_work(&patch->free_work); | |
730 | } | |
731 | ||
732 | void klp_free_replaced_patches_async(struct klp_patch *new_patch) | |
733 | { | |
734 | struct klp_patch *old_patch, *tmp_patch; | |
735 | ||
736 | klp_for_each_patch_safe(old_patch, tmp_patch) { | |
737 | if (old_patch == new_patch) | |
738 | return; | |
739 | klp_free_patch_async(old_patch); | |
740 | } | |
741 | } | |
742 | ||
b700e7f0 SJ |
743 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) |
744 | { | |
e1452b60 JB |
745 | if (!func->old_name) |
746 | return -EINVAL; | |
747 | ||
748 | /* | |
749 | * NOPs get the address later. The patched module must be loaded, | |
750 | * see klp_init_object_loaded(). | |
751 | */ | |
752 | if (!func->new_func && !func->nop) | |
f09d9086 MB |
753 | return -EINVAL; |
754 | ||
6e9df95b KB |
755 | if (strlen(func->old_name) >= KSYM_NAME_LEN) |
756 | return -EINVAL; | |
757 | ||
3c33f5b9 | 758 | INIT_LIST_HEAD(&func->stack_node); |
0dade9f3 | 759 | func->patched = false; |
d83a7cb3 | 760 | func->transition = false; |
b700e7f0 | 761 | |
444f9e99 CA |
762 | /* The format for the sysfs directory is <function,sympos> where sympos |
763 | * is the nth occurrence of this symbol in kallsyms for the patched | |
764 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
765 | * since a unique symbol will be the first occurrence. | |
766 | */ | |
4d141ab3 PM |
767 | return kobject_add(&func->kobj, &obj->kobj, "%s,%lu", |
768 | func->old_name, | |
769 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
770 | } |
771 | ||
a4ae16f6 SZ |
772 | static int klp_apply_object_relocs(struct klp_patch *patch, |
773 | struct klp_object *obj) | |
7c8e2bdd JP |
774 | { |
775 | int i, ret; | |
776 | struct klp_modinfo *info = patch->mod->klp_info; | |
777 | ||
778 | for (i = 1; i < info->hdr.e_shnum; i++) { | |
779 | Elf_Shdr *sec = info->sechdrs + i; | |
780 | ||
781 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
782 | continue; | |
783 | ||
784 | ret = klp_apply_section_relocs(patch->mod, info->sechdrs, | |
785 | info->secstrings, | |
786 | patch->mod->core_kallsyms.strtab, | |
787 | info->symndx, i, obj->name); | |
788 | if (ret) | |
789 | return ret; | |
790 | } | |
791 | ||
792 | return 0; | |
793 | } | |
794 | ||
b700e7f0 SJ |
795 | /* parts of the initialization that is done only when the object is loaded */ |
796 | static int klp_init_object_loaded(struct klp_patch *patch, | |
797 | struct klp_object *obj) | |
798 | { | |
799 | struct klp_func *func; | |
800 | int ret; | |
801 | ||
7c8e2bdd JP |
802 | if (klp_is_module(obj)) { |
803 | /* | |
804 | * Only write module-specific relocations here | |
805 | * (.klp.rela.{module}.*). vmlinux-specific relocations were | |
806 | * written earlier during the initialization of the klp module | |
807 | * itself. | |
808 | */ | |
809 | ret = klp_apply_object_relocs(patch, obj); | |
1d05334d PZ |
810 | if (ret) |
811 | return ret; | |
812 | } | |
9f255b63 | 813 | |
8cdd043a | 814 | klp_for_each_func(obj, func) { |
b2b018ef CA |
815 | ret = klp_find_object_symbol(obj->name, func->old_name, |
816 | func->old_sympos, | |
19514910 | 817 | (unsigned long *)&func->old_func); |
b700e7f0 SJ |
818 | if (ret) |
819 | return ret; | |
f5e547f4 | 820 | |
19514910 | 821 | ret = kallsyms_lookup_size_offset((unsigned long)func->old_func, |
f5e547f4 JP |
822 | &func->old_size, NULL); |
823 | if (!ret) { | |
824 | pr_err("kallsyms size lookup failed for '%s'\n", | |
825 | func->old_name); | |
826 | return -ENOENT; | |
827 | } | |
828 | ||
e1452b60 JB |
829 | if (func->nop) |
830 | func->new_func = func->old_func; | |
831 | ||
f5e547f4 JP |
832 | ret = kallsyms_lookup_size_offset((unsigned long)func->new_func, |
833 | &func->new_size, NULL); | |
834 | if (!ret) { | |
835 | pr_err("kallsyms size lookup failed for '%s' replacement\n", | |
836 | func->old_name); | |
837 | return -ENOENT; | |
838 | } | |
b700e7f0 SJ |
839 | } |
840 | ||
841 | return 0; | |
842 | } | |
843 | ||
844 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
845 | { | |
846 | struct klp_func *func; | |
847 | int ret; | |
848 | const char *name; | |
849 | ||
6e9df95b KB |
850 | if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN) |
851 | return -EINVAL; | |
852 | ||
0dade9f3 | 853 | obj->patched = false; |
8cb2c2dc | 854 | obj->mod = NULL; |
b700e7f0 SJ |
855 | |
856 | klp_find_object_module(obj); | |
857 | ||
858 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
4d141ab3 | 859 | ret = kobject_add(&obj->kobj, &patch->kobj, "%s", name); |
cad706df MB |
860 | if (ret) |
861 | return ret; | |
b700e7f0 | 862 | |
8cdd043a | 863 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
864 | ret = klp_init_func(obj, func); |
865 | if (ret) | |
0430f78b | 866 | return ret; |
b700e7f0 SJ |
867 | } |
868 | ||
0430f78b | 869 | if (klp_is_object_loaded(obj)) |
b700e7f0 | 870 | ret = klp_init_object_loaded(patch, obj); |
b700e7f0 | 871 | |
b700e7f0 SJ |
872 | return ret; |
873 | } | |
874 | ||
f68d67cf PM |
875 | static void klp_init_func_early(struct klp_object *obj, |
876 | struct klp_func *func) | |
877 | { | |
878 | kobject_init(&func->kobj, &klp_ktype_func); | |
879 | list_add_tail(&func->node, &obj->func_list); | |
880 | } | |
881 | ||
882 | static void klp_init_object_early(struct klp_patch *patch, | |
883 | struct klp_object *obj) | |
884 | { | |
885 | INIT_LIST_HEAD(&obj->func_list); | |
886 | kobject_init(&obj->kobj, &klp_ktype_object); | |
887 | list_add_tail(&obj->node, &patch->obj_list); | |
888 | } | |
889 | ||
5ef3dd20 | 890 | static void klp_init_patch_early(struct klp_patch *patch) |
b700e7f0 SJ |
891 | { |
892 | struct klp_object *obj; | |
0430f78b | 893 | struct klp_func *func; |
b700e7f0 | 894 | |
0430f78b | 895 | INIT_LIST_HEAD(&patch->list); |
20e55025 | 896 | INIT_LIST_HEAD(&patch->obj_list); |
4d141ab3 | 897 | kobject_init(&patch->kobj, &klp_ktype_patch); |
0dade9f3 | 898 | patch->enabled = false; |
68007289 | 899 | patch->forced = false; |
958ef1e3 | 900 | INIT_WORK(&patch->free_work, klp_free_patch_work_fn); |
3ec24776 | 901 | init_completion(&patch->finish); |
b700e7f0 | 902 | |
20e55025 | 903 | klp_for_each_object_static(patch, obj) { |
f68d67cf | 904 | klp_init_object_early(patch, obj); |
0430f78b | 905 | |
20e55025 | 906 | klp_for_each_func_static(obj, func) { |
f68d67cf | 907 | klp_init_func_early(obj, func); |
20e55025 | 908 | } |
0430f78b | 909 | } |
0430f78b PM |
910 | } |
911 | ||
912 | static int klp_init_patch(struct klp_patch *patch) | |
913 | { | |
914 | struct klp_object *obj; | |
915 | int ret; | |
916 | ||
4d141ab3 | 917 | ret = kobject_add(&patch->kobj, klp_root_kobj, "%s", patch->mod->name); |
958ef1e3 | 918 | if (ret) |
3ec24776 | 919 | return ret; |
b700e7f0 | 920 | |
e1452b60 JB |
921 | if (patch->replace) { |
922 | ret = klp_add_nops(patch); | |
923 | if (ret) | |
924 | return ret; | |
925 | } | |
926 | ||
8cdd043a | 927 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
928 | ret = klp_init_object(patch, obj); |
929 | if (ret) | |
958ef1e3 | 930 | return ret; |
b700e7f0 SJ |
931 | } |
932 | ||
99590ba5 | 933 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 | 934 | |
3ec24776 | 935 | return 0; |
b700e7f0 | 936 | } |
b700e7f0 | 937 | |
26c3e98e PM |
938 | static int __klp_disable_patch(struct klp_patch *patch) |
939 | { | |
940 | struct klp_object *obj; | |
941 | ||
942 | if (WARN_ON(!patch->enabled)) | |
943 | return -EINVAL; | |
944 | ||
945 | if (klp_transition_patch) | |
946 | return -EBUSY; | |
947 | ||
26c3e98e PM |
948 | klp_init_transition(patch, KLP_UNPATCHED); |
949 | ||
950 | klp_for_each_object(patch, obj) | |
951 | if (obj->patched) | |
952 | klp_pre_unpatch_callback(obj); | |
953 | ||
954 | /* | |
955 | * Enforce the order of the func->transition writes in | |
956 | * klp_init_transition() and the TIF_PATCH_PENDING writes in | |
957 | * klp_start_transition(). In the rare case where klp_ftrace_handler() | |
958 | * is called shortly after klp_update_patch_state() switches the task, | |
959 | * this ensures the handler sees that func->transition is set. | |
960 | */ | |
961 | smp_wmb(); | |
962 | ||
963 | klp_start_transition(); | |
26c3e98e | 964 | patch->enabled = false; |
958ef1e3 | 965 | klp_try_complete_transition(); |
26c3e98e PM |
966 | |
967 | return 0; | |
968 | } | |
969 | ||
26c3e98e PM |
970 | static int __klp_enable_patch(struct klp_patch *patch) |
971 | { | |
972 | struct klp_object *obj; | |
973 | int ret; | |
974 | ||
975 | if (klp_transition_patch) | |
976 | return -EBUSY; | |
977 | ||
978 | if (WARN_ON(patch->enabled)) | |
979 | return -EINVAL; | |
980 | ||
26c3e98e PM |
981 | pr_notice("enabling patch '%s'\n", patch->mod->name); |
982 | ||
983 | klp_init_transition(patch, KLP_PATCHED); | |
984 | ||
985 | /* | |
986 | * Enforce the order of the func->transition writes in | |
987 | * klp_init_transition() and the ops->func_stack writes in | |
988 | * klp_patch_object(), so that klp_ftrace_handler() will see the | |
989 | * func->transition updates before the handler is registered and the | |
990 | * new funcs become visible to the handler. | |
991 | */ | |
992 | smp_wmb(); | |
993 | ||
994 | klp_for_each_object(patch, obj) { | |
995 | if (!klp_is_object_loaded(obj)) | |
996 | continue; | |
997 | ||
998 | ret = klp_pre_patch_callback(obj); | |
999 | if (ret) { | |
1000 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1001 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
1002 | goto err; | |
1003 | } | |
1004 | ||
1005 | ret = klp_patch_object(obj); | |
1006 | if (ret) { | |
1007 | pr_warn("failed to patch object '%s'\n", | |
1008 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
1009 | goto err; | |
1010 | } | |
1011 | } | |
1012 | ||
1013 | klp_start_transition(); | |
26c3e98e | 1014 | patch->enabled = true; |
958ef1e3 | 1015 | klp_try_complete_transition(); |
26c3e98e PM |
1016 | |
1017 | return 0; | |
1018 | err: | |
1019 | pr_warn("failed to enable patch '%s'\n", patch->mod->name); | |
1020 | ||
1021 | klp_cancel_transition(); | |
1022 | return ret; | |
1023 | } | |
1024 | ||
1025 | /** | |
958ef1e3 PM |
1026 | * klp_enable_patch() - enable the livepatch |
1027 | * @patch: patch to be enabled | |
26c3e98e | 1028 | * |
958ef1e3 PM |
1029 | * Initializes the data structure associated with the patch, creates the sysfs |
1030 | * interface, performs the needed symbol lookups and code relocations, | |
1031 | * registers the patched functions with ftrace. | |
1032 | * | |
1033 | * This function is supposed to be called from the livepatch module_init() | |
1034 | * callback. | |
26c3e98e PM |
1035 | * |
1036 | * Return: 0 on success, otherwise error | |
1037 | */ | |
1038 | int klp_enable_patch(struct klp_patch *patch) | |
1039 | { | |
1040 | int ret; | |
5ef3dd20 | 1041 | struct klp_object *obj; |
26c3e98e | 1042 | |
5ef3dd20 | 1043 | if (!patch || !patch->mod || !patch->objs) |
958ef1e3 PM |
1044 | return -EINVAL; |
1045 | ||
5ef3dd20 DV |
1046 | klp_for_each_object_static(patch, obj) { |
1047 | if (!obj->funcs) | |
1048 | return -EINVAL; | |
1049 | } | |
1050 | ||
1051 | ||
958ef1e3 PM |
1052 | if (!is_livepatch_module(patch->mod)) { |
1053 | pr_err("module %s is not marked as a livepatch module\n", | |
1054 | patch->mod->name); | |
1055 | return -EINVAL; | |
1056 | } | |
1057 | ||
1058 | if (!klp_initialized()) | |
1059 | return -ENODEV; | |
1060 | ||
1061 | if (!klp_have_reliable_stack()) { | |
31adf230 PM |
1062 | pr_warn("This architecture doesn't have support for the livepatch consistency model.\n"); |
1063 | pr_warn("The livepatch transition may never complete.\n"); | |
958ef1e3 PM |
1064 | } |
1065 | ||
26c3e98e PM |
1066 | mutex_lock(&klp_mutex); |
1067 | ||
92c9abf5 PM |
1068 | if (!klp_is_patch_compatible(patch)) { |
1069 | pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n", | |
1070 | patch->mod->name); | |
1071 | mutex_unlock(&klp_mutex); | |
1072 | return -EINVAL; | |
1073 | } | |
1074 | ||
50a0f3f5 YY |
1075 | if (!try_module_get(patch->mod)) { |
1076 | mutex_unlock(&klp_mutex); | |
5ef3dd20 | 1077 | return -ENODEV; |
50a0f3f5 | 1078 | } |
5ef3dd20 DV |
1079 | |
1080 | klp_init_patch_early(patch); | |
26c3e98e | 1081 | |
958ef1e3 PM |
1082 | ret = klp_init_patch(patch); |
1083 | if (ret) | |
1084 | goto err; | |
1085 | ||
26c3e98e | 1086 | ret = __klp_enable_patch(patch); |
958ef1e3 PM |
1087 | if (ret) |
1088 | goto err; | |
1089 | ||
1090 | mutex_unlock(&klp_mutex); | |
1091 | ||
1092 | return 0; | |
26c3e98e PM |
1093 | |
1094 | err: | |
958ef1e3 PM |
1095 | klp_free_patch_start(patch); |
1096 | ||
26c3e98e | 1097 | mutex_unlock(&klp_mutex); |
958ef1e3 PM |
1098 | |
1099 | klp_free_patch_finish(patch); | |
1100 | ||
26c3e98e PM |
1101 | return ret; |
1102 | } | |
1103 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
1104 | ||
e1452b60 | 1105 | /* |
7e35e4eb | 1106 | * This function unpatches objects from the replaced livepatches. |
e1452b60 JB |
1107 | * |
1108 | * We could be pretty aggressive here. It is called in the situation where | |
7e35e4eb PM |
1109 | * these structures are no longer accessed from the ftrace handler. |
1110 | * All functions are redirected by the klp_transition_patch. They | |
1111 | * use either a new code or they are in the original code because | |
1112 | * of the special nop function patches. | |
e1452b60 JB |
1113 | * |
1114 | * The only exception is when the transition was forced. In this case, | |
1115 | * klp_ftrace_handler() might still see the replaced patch on the stack. | |
1116 | * Fortunately, it is carefully designed to work with removed functions | |
1117 | * thanks to RCU. We only have to keep the patches on the system. Also | |
1118 | * this is handled transparently by patch->module_put. | |
1119 | */ | |
7e35e4eb | 1120 | void klp_unpatch_replaced_patches(struct klp_patch *new_patch) |
e1452b60 | 1121 | { |
7e35e4eb | 1122 | struct klp_patch *old_patch; |
e1452b60 | 1123 | |
7e35e4eb | 1124 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
1125 | if (old_patch == new_patch) |
1126 | return; | |
1127 | ||
1128 | old_patch->enabled = false; | |
1129 | klp_unpatch_objects(old_patch); | |
e1452b60 JB |
1130 | } |
1131 | } | |
1132 | ||
d697bad5 PM |
1133 | /* |
1134 | * This function removes the dynamically allocated 'nop' functions. | |
1135 | * | |
1136 | * We could be pretty aggressive. NOPs do not change the existing | |
1137 | * behavior except for adding unnecessary delay by the ftrace handler. | |
1138 | * | |
1139 | * It is safe even when the transition was forced. The ftrace handler | |
1140 | * will see a valid ops->func_stack entry thanks to RCU. | |
1141 | * | |
1142 | * We could even free the NOPs structures. They must be the last entry | |
1143 | * in ops->func_stack. Therefore unregister_ftrace_function() is called. | |
1144 | * It does the same as klp_synchronize_transition() to make sure that | |
1145 | * nobody is inside the ftrace handler once the operation finishes. | |
1146 | * | |
1147 | * IMPORTANT: It must be called right after removing the replaced patches! | |
1148 | */ | |
1149 | void klp_discard_nops(struct klp_patch *new_patch) | |
1150 | { | |
1151 | klp_unpatch_objects_dynamic(klp_transition_patch); | |
1152 | klp_free_objects_dynamic(klp_transition_patch); | |
1153 | } | |
1154 | ||
ef8daf8e JL |
1155 | /* |
1156 | * Remove parts of patches that touch a given kernel module. The list of | |
1157 | * patches processed might be limited. When limit is NULL, all patches | |
1158 | * will be handled. | |
1159 | */ | |
1160 | static void klp_cleanup_module_patches_limited(struct module *mod, | |
1161 | struct klp_patch *limit) | |
1162 | { | |
1163 | struct klp_patch *patch; | |
1164 | struct klp_object *obj; | |
1165 | ||
ecba29f4 | 1166 | klp_for_each_patch(patch) { |
ef8daf8e JL |
1167 | if (patch == limit) |
1168 | break; | |
1169 | ||
1170 | klp_for_each_object(patch, obj) { | |
1171 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1172 | continue; | |
1173 | ||
a087cdd4 PM |
1174 | if (patch != klp_transition_patch) |
1175 | klp_pre_unpatch_callback(obj); | |
fc41efc1 | 1176 | |
a087cdd4 PM |
1177 | pr_notice("reverting patch '%s' on unloading module '%s'\n", |
1178 | patch->mod->name, obj->mod->name); | |
1179 | klp_unpatch_object(obj); | |
fc41efc1 | 1180 | |
a087cdd4 | 1181 | klp_post_unpatch_callback(obj); |
ef8daf8e JL |
1182 | |
1183 | klp_free_object_loaded(obj); | |
1184 | break; | |
1185 | } | |
1186 | } | |
1187 | } | |
1188 | ||
7e545d6e | 1189 | int klp_module_coming(struct module *mod) |
b700e7f0 | 1190 | { |
b700e7f0 | 1191 | int ret; |
7e545d6e JY |
1192 | struct klp_patch *patch; |
1193 | struct klp_object *obj; | |
b700e7f0 | 1194 | |
7e545d6e JY |
1195 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
1196 | return -EINVAL; | |
b700e7f0 | 1197 | |
dcf550e5 | 1198 | if (!strcmp(mod->name, "vmlinux")) { |
66d8529d | 1199 | pr_err("vmlinux.ko: invalid module name\n"); |
dcf550e5 JP |
1200 | return -EINVAL; |
1201 | } | |
1202 | ||
7e545d6e JY |
1203 | mutex_lock(&klp_mutex); |
1204 | /* | |
1205 | * Each module has to know that klp_module_coming() | |
1206 | * has been called. We never know what module will | |
1207 | * get patched by a new patch. | |
1208 | */ | |
1209 | mod->klp_alive = true; | |
b700e7f0 | 1210 | |
ecba29f4 | 1211 | klp_for_each_patch(patch) { |
7e545d6e JY |
1212 | klp_for_each_object(patch, obj) { |
1213 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1214 | continue; | |
b700e7f0 | 1215 | |
7e545d6e | 1216 | obj->mod = mod; |
b700e7f0 | 1217 | |
7e545d6e JY |
1218 | ret = klp_init_object_loaded(patch, obj); |
1219 | if (ret) { | |
1220 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
1221 | patch->mod->name, obj->mod->name, ret); | |
1222 | goto err; | |
1223 | } | |
b700e7f0 | 1224 | |
7e545d6e JY |
1225 | pr_notice("applying patch '%s' to loading module '%s'\n", |
1226 | patch->mod->name, obj->mod->name); | |
1227 | ||
93862e38 JL |
1228 | ret = klp_pre_patch_callback(obj); |
1229 | if (ret) { | |
1230 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1231 | obj->name); | |
1232 | goto err; | |
1233 | } | |
1234 | ||
0dade9f3 | 1235 | ret = klp_patch_object(obj); |
7e545d6e JY |
1236 | if (ret) { |
1237 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
1238 | patch->mod->name, obj->mod->name, ret); | |
93862e38 | 1239 | |
5aaf1ab5 | 1240 | klp_post_unpatch_callback(obj); |
7e545d6e JY |
1241 | goto err; |
1242 | } | |
1243 | ||
93862e38 JL |
1244 | if (patch != klp_transition_patch) |
1245 | klp_post_patch_callback(obj); | |
1246 | ||
7e545d6e JY |
1247 | break; |
1248 | } | |
1249 | } | |
b700e7f0 | 1250 | |
7e545d6e | 1251 | mutex_unlock(&klp_mutex); |
b700e7f0 | 1252 | |
7e545d6e | 1253 | return 0; |
b700e7f0 | 1254 | |
7e545d6e JY |
1255 | err: |
1256 | /* | |
1257 | * If a patch is unsuccessfully applied, return | |
1258 | * error to the module loader. | |
1259 | */ | |
1260 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
1261 | patch->mod->name, obj->mod->name, obj->mod->name); | |
1262 | mod->klp_alive = false; | |
4ff96fb5 | 1263 | obj->mod = NULL; |
ef8daf8e | 1264 | klp_cleanup_module_patches_limited(mod, patch); |
7e545d6e JY |
1265 | mutex_unlock(&klp_mutex); |
1266 | ||
1267 | return ret; | |
b700e7f0 SJ |
1268 | } |
1269 | ||
7e545d6e | 1270 | void klp_module_going(struct module *mod) |
b700e7f0 | 1271 | { |
7e545d6e JY |
1272 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1273 | mod->state != MODULE_STATE_COMING)) | |
1274 | return; | |
b700e7f0 SJ |
1275 | |
1276 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1277 | /* |
7e545d6e JY |
1278 | * Each module has to know that klp_module_going() |
1279 | * has been called. We never know what module will | |
1280 | * get patched by a new patch. | |
8cb2c2dc | 1281 | */ |
7e545d6e | 1282 | mod->klp_alive = false; |
8cb2c2dc | 1283 | |
ef8daf8e | 1284 | klp_cleanup_module_patches_limited(mod, NULL); |
b700e7f0 SJ |
1285 | |
1286 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1287 | } |
1288 | ||
26029d88 | 1289 | static int __init klp_init(void) |
b700e7f0 | 1290 | { |
b700e7f0 | 1291 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1292 | if (!klp_root_kobj) |
1293 | return -ENOMEM; | |
b700e7f0 SJ |
1294 | |
1295 | return 0; | |
b700e7f0 SJ |
1296 | } |
1297 | ||
1298 | module_init(klp_init); |