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 | 120 | struct klp_find_arg { |
b700e7f0 SJ |
121 | const char *name; |
122 | unsigned long addr; | |
b700e7f0 | 123 | unsigned long count; |
b2b018ef | 124 | unsigned long pos; |
b700e7f0 SJ |
125 | }; |
126 | ||
4f1354d5 | 127 | static int klp_match_callback(void *data, unsigned long addr) |
b700e7f0 SJ |
128 | { |
129 | struct klp_find_arg *args = data; | |
130 | ||
b700e7f0 SJ |
131 | args->addr = addr; |
132 | args->count++; | |
133 | ||
b2b018ef CA |
134 | /* |
135 | * Finish the search when the symbol is found for the desired position | |
136 | * or the position is not defined for a non-unique symbol. | |
137 | */ | |
138 | if ((args->pos && (args->count == args->pos)) || | |
139 | (!args->pos && (args->count > 1))) | |
140 | return 1; | |
141 | ||
b700e7f0 SJ |
142 | return 0; |
143 | } | |
144 | ||
4f1354d5 ZL |
145 | static int klp_find_callback(void *data, const char *name, |
146 | struct module *mod, unsigned long addr) | |
9cb37357 ZL |
147 | { |
148 | struct klp_find_arg *args = data; | |
149 | ||
4f1354d5 ZL |
150 | if (strcmp(args->name, name)) |
151 | return 0; | |
9cb37357 | 152 | |
4f1354d5 | 153 | return klp_match_callback(data, addr); |
9cb37357 ZL |
154 | } |
155 | ||
b700e7f0 | 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 = { | |
b700e7f0 SJ |
160 | .name = name, |
161 | .addr = 0, | |
b2b018ef CA |
162 | .count = 0, |
163 | .pos = sympos, | |
b700e7f0 SJ |
164 | }; |
165 | ||
72f04b50 | 166 | if (objname) |
07cc2c93 | 167 | module_kallsyms_on_each_symbol(objname, klp_find_callback, &args); |
72f04b50 | 168 | else |
9cb37357 | 169 | kallsyms_on_each_match_symbol(klp_match_callback, name, &args); |
b700e7f0 | 170 | |
b2b018ef CA |
171 | /* |
172 | * Ensure an address was found. If sympos is 0, ensure symbol is unique; | |
173 | * otherwise ensure the symbol position count matches sympos. | |
174 | */ | |
175 | if (args.addr == 0) | |
b700e7f0 | 176 | pr_err("symbol '%s' not found in symbol table\n", name); |
b2b018ef | 177 | else if (args.count > 1 && sympos == 0) { |
f995b5f7 PM |
178 | pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n", |
179 | name, objname); | |
b2b018ef CA |
180 | } else if (sympos != args.count && sympos > 0) { |
181 | pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n", | |
182 | sympos, name, objname ? objname : "vmlinux"); | |
183 | } else { | |
b700e7f0 SJ |
184 | *addr = args.addr; |
185 | return 0; | |
186 | } | |
187 | ||
188 | *addr = 0; | |
189 | return -EINVAL; | |
190 | } | |
191 | ||
2f293651 | 192 | static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, |
ca376a93 JP |
193 | unsigned int symndx, Elf_Shdr *relasec, |
194 | const char *sec_objname) | |
b700e7f0 | 195 | { |
ca376a93 JP |
196 | int i, cnt, ret; |
197 | char sym_objname[MODULE_NAME_LEN]; | |
198 | char sym_name[KSYM_NAME_LEN]; | |
425595a7 JY |
199 | Elf_Rela *relas; |
200 | Elf_Sym *sym; | |
201 | unsigned long sympos, addr; | |
ca376a93 JP |
202 | bool sym_vmlinux; |
203 | bool sec_vmlinux = !strcmp(sec_objname, "vmlinux"); | |
b700e7f0 | 204 | |
b2b018ef | 205 | /* |
ca376a93 | 206 | * Since the field widths for sym_objname and sym_name in the sscanf() |
425595a7 JY |
207 | * call are hard-coded and correspond to MODULE_NAME_LEN and |
208 | * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN | |
209 | * and KSYM_NAME_LEN have the values we expect them to have. | |
210 | * | |
211 | * Because the value of MODULE_NAME_LEN can differ among architectures, | |
212 | * we use the smallest/strictest upper bound possible (56, based on | |
213 | * the current definition of MODULE_NAME_LEN) to prevent overflows. | |
b2b018ef | 214 | */ |
b8a94bfb | 215 | BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512); |
425595a7 JY |
216 | |
217 | relas = (Elf_Rela *) relasec->sh_addr; | |
218 | /* For each rela in this klp relocation section */ | |
219 | for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { | |
2f293651 | 220 | sym = (Elf_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info); |
425595a7 | 221 | if (sym->st_shndx != SHN_LIVEPATCH) { |
77f8f39a | 222 | pr_err("symbol %s is not marked as a livepatch symbol\n", |
425595a7 JY |
223 | strtab + sym->st_name); |
224 | return -EINVAL; | |
225 | } | |
226 | ||
ca376a93 | 227 | /* Format: .klp.sym.sym_objname.sym_name,sympos */ |
425595a7 | 228 | cnt = sscanf(strtab + sym->st_name, |
b8a94bfb | 229 | ".klp.sym.%55[^.].%511[^,],%lu", |
ca376a93 | 230 | sym_objname, sym_name, &sympos); |
425595a7 | 231 | if (cnt != 3) { |
77f8f39a | 232 | pr_err("symbol %s has an incorrectly formatted name\n", |
425595a7 JY |
233 | strtab + sym->st_name); |
234 | return -EINVAL; | |
235 | } | |
236 | ||
ca376a93 JP |
237 | sym_vmlinux = !strcmp(sym_objname, "vmlinux"); |
238 | ||
239 | /* | |
240 | * Prevent module-specific KLP rela sections from referencing | |
241 | * vmlinux symbols. This helps prevent ordering issues with | |
242 | * module special section initializations. Presumably such | |
243 | * symbols are exported and normal relas can be used instead. | |
244 | */ | |
245 | if (!sec_vmlinux && sym_vmlinux) { | |
246 | pr_err("invalid access to vmlinux symbol '%s' from module-specific livepatch relocation section", | |
247 | sym_name); | |
248 | return -EINVAL; | |
249 | } | |
250 | ||
425595a7 | 251 | /* klp_find_object_symbol() treats a NULL objname as vmlinux */ |
ca376a93 JP |
252 | ret = klp_find_object_symbol(sym_vmlinux ? NULL : sym_objname, |
253 | sym_name, sympos, &addr); | |
425595a7 JY |
254 | if (ret) |
255 | return ret; | |
256 | ||
257 | sym->st_value = addr; | |
258 | } | |
259 | ||
260 | return 0; | |
b700e7f0 SJ |
261 | } |
262 | ||
0c05e7bd SL |
263 | void __weak clear_relocate_add(Elf_Shdr *sechdrs, |
264 | const char *strtab, | |
265 | unsigned int symindex, | |
266 | unsigned int relsec, | |
267 | struct module *me) | |
268 | { | |
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 | */ | |
0c05e7bd SL |
294 | static int klp_write_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, bool apply) | |
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 | |
0c05e7bd SL |
319 | if (apply) { |
320 | ret = klp_resolve_symbols(sechdrs, strtab, symndx, | |
321 | sec, sec_objname); | |
322 | if (ret) | |
323 | return ret; | |
324 | ||
325 | return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); | |
326 | } | |
327 | ||
328 | clear_relocate_add(sechdrs, strtab, symndx, secndx, pmod); | |
329 | return 0; | |
330 | } | |
b700e7f0 | 331 | |
0c05e7bd SL |
332 | int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, |
333 | const char *shstrtab, const char *strtab, | |
334 | unsigned int symndx, unsigned int secndx, | |
335 | const char *objname) | |
336 | { | |
337 | return klp_write_section_relocs(pmod, sechdrs, shstrtab, strtab, symndx, | |
338 | secndx, objname, true); | |
b700e7f0 SJ |
339 | } |
340 | ||
b700e7f0 SJ |
341 | /* |
342 | * Sysfs Interface | |
343 | * | |
344 | * /sys/kernel/livepatch | |
345 | * /sys/kernel/livepatch/<patch> | |
346 | * /sys/kernel/livepatch/<patch>/enabled | |
d83a7cb3 | 347 | * /sys/kernel/livepatch/<patch>/transition |
c99a2be7 | 348 | * /sys/kernel/livepatch/<patch>/force |
b700e7f0 | 349 | * /sys/kernel/livepatch/<patch>/<object> |
bb26cfd9 | 350 | * /sys/kernel/livepatch/<patch>/<object>/patched |
444f9e99 | 351 | * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> |
b700e7f0 | 352 | */ |
26c3e98e | 353 | static int __klp_disable_patch(struct klp_patch *patch); |
b700e7f0 SJ |
354 | |
355 | static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, | |
356 | const char *buf, size_t count) | |
357 | { | |
358 | struct klp_patch *patch; | |
359 | int ret; | |
68ae4b2b | 360 | bool enabled; |
b700e7f0 | 361 | |
68ae4b2b | 362 | ret = kstrtobool(buf, &enabled); |
b700e7f0 | 363 | if (ret) |
68ae4b2b | 364 | return ret; |
b700e7f0 SJ |
365 | |
366 | patch = container_of(kobj, struct klp_patch, kobj); | |
367 | ||
368 | mutex_lock(&klp_mutex); | |
369 | ||
68ae4b2b | 370 | if (patch->enabled == enabled) { |
b700e7f0 SJ |
371 | /* already in requested state */ |
372 | ret = -EINVAL; | |
958ef1e3 | 373 | goto out; |
b700e7f0 SJ |
374 | } |
375 | ||
958ef1e3 PM |
376 | /* |
377 | * Allow to reverse a pending transition in both ways. It might be | |
378 | * necessary to complete the transition without forcing and breaking | |
379 | * the system integrity. | |
380 | * | |
381 | * Do not allow to re-enable a disabled patch. | |
382 | */ | |
383 | if (patch == klp_transition_patch) | |
d83a7cb3 | 384 | klp_reverse_transition(); |
958ef1e3 | 385 | else if (!enabled) |
b700e7f0 | 386 | ret = __klp_disable_patch(patch); |
958ef1e3 PM |
387 | else |
388 | ret = -EINVAL; | |
b700e7f0 | 389 | |
958ef1e3 | 390 | out: |
b700e7f0 SJ |
391 | mutex_unlock(&klp_mutex); |
392 | ||
958ef1e3 PM |
393 | if (ret) |
394 | return ret; | |
b700e7f0 | 395 | return count; |
b700e7f0 SJ |
396 | } |
397 | ||
398 | static ssize_t enabled_show(struct kobject *kobj, | |
399 | struct kobj_attribute *attr, char *buf) | |
400 | { | |
401 | struct klp_patch *patch; | |
402 | ||
403 | patch = container_of(kobj, struct klp_patch, kobj); | |
0dade9f3 | 404 | return snprintf(buf, PAGE_SIZE-1, "%d\n", patch->enabled); |
b700e7f0 SJ |
405 | } |
406 | ||
d83a7cb3 JP |
407 | static ssize_t transition_show(struct kobject *kobj, |
408 | struct kobj_attribute *attr, char *buf) | |
409 | { | |
410 | struct klp_patch *patch; | |
411 | ||
412 | patch = container_of(kobj, struct klp_patch, kobj); | |
413 | return snprintf(buf, PAGE_SIZE-1, "%d\n", | |
414 | patch == klp_transition_patch); | |
b700e7f0 SJ |
415 | } |
416 | ||
c99a2be7 MB |
417 | static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, |
418 | const char *buf, size_t count) | |
419 | { | |
420 | struct klp_patch *patch; | |
421 | int ret; | |
422 | bool val; | |
423 | ||
c99a2be7 MB |
424 | ret = kstrtobool(buf, &val); |
425 | if (ret) | |
426 | return ret; | |
427 | ||
8869016d MB |
428 | if (!val) |
429 | return count; | |
430 | ||
431 | mutex_lock(&klp_mutex); | |
432 | ||
433 | patch = container_of(kobj, struct klp_patch, kobj); | |
434 | if (patch != klp_transition_patch) { | |
435 | mutex_unlock(&klp_mutex); | |
436 | return -EINVAL; | |
437 | } | |
438 | ||
439 | klp_force_transition(); | |
440 | ||
441 | mutex_unlock(&klp_mutex); | |
c99a2be7 MB |
442 | |
443 | return count; | |
444 | } | |
445 | ||
b700e7f0 | 446 | static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); |
d83a7cb3 | 447 | static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); |
c99a2be7 | 448 | static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); |
b700e7f0 SJ |
449 | static struct attribute *klp_patch_attrs[] = { |
450 | &enabled_kobj_attr.attr, | |
d83a7cb3 | 451 | &transition_kobj_attr.attr, |
c99a2be7 | 452 | &force_kobj_attr.attr, |
b700e7f0 SJ |
453 | NULL |
454 | }; | |
70283454 | 455 | ATTRIBUTE_GROUPS(klp_patch); |
b700e7f0 | 456 | |
bb26cfd9 SL |
457 | static ssize_t patched_show(struct kobject *kobj, |
458 | struct kobj_attribute *attr, char *buf) | |
459 | { | |
460 | struct klp_object *obj; | |
461 | ||
462 | obj = container_of(kobj, struct klp_object, kobj); | |
463 | return sysfs_emit(buf, "%d\n", obj->patched); | |
464 | } | |
465 | ||
466 | static struct kobj_attribute patched_kobj_attr = __ATTR_RO(patched); | |
467 | static struct attribute *klp_object_attrs[] = { | |
468 | &patched_kobj_attr.attr, | |
469 | NULL, | |
470 | }; | |
471 | ATTRIBUTE_GROUPS(klp_object); | |
472 | ||
e1452b60 JB |
473 | static void klp_free_object_dynamic(struct klp_object *obj) |
474 | { | |
475 | kfree(obj->name); | |
476 | kfree(obj); | |
477 | } | |
478 | ||
f68d67cf PM |
479 | static void klp_init_func_early(struct klp_object *obj, |
480 | struct klp_func *func); | |
481 | static void klp_init_object_early(struct klp_patch *patch, | |
482 | struct klp_object *obj); | |
4d141ab3 | 483 | |
f68d67cf PM |
484 | static struct klp_object *klp_alloc_object_dynamic(const char *name, |
485 | struct klp_patch *patch) | |
e1452b60 JB |
486 | { |
487 | struct klp_object *obj; | |
488 | ||
489 | obj = kzalloc(sizeof(*obj), GFP_KERNEL); | |
490 | if (!obj) | |
491 | return NULL; | |
492 | ||
493 | if (name) { | |
494 | obj->name = kstrdup(name, GFP_KERNEL); | |
495 | if (!obj->name) { | |
496 | kfree(obj); | |
497 | return NULL; | |
498 | } | |
499 | } | |
500 | ||
f68d67cf | 501 | klp_init_object_early(patch, obj); |
e1452b60 JB |
502 | obj->dynamic = true; |
503 | ||
504 | return obj; | |
505 | } | |
506 | ||
507 | static void klp_free_func_nop(struct klp_func *func) | |
508 | { | |
509 | kfree(func->old_name); | |
510 | kfree(func); | |
511 | } | |
512 | ||
513 | static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func, | |
514 | struct klp_object *obj) | |
515 | { | |
516 | struct klp_func *func; | |
517 | ||
518 | func = kzalloc(sizeof(*func), GFP_KERNEL); | |
519 | if (!func) | |
520 | return NULL; | |
521 | ||
522 | if (old_func->old_name) { | |
523 | func->old_name = kstrdup(old_func->old_name, GFP_KERNEL); | |
524 | if (!func->old_name) { | |
525 | kfree(func); | |
526 | return NULL; | |
527 | } | |
528 | } | |
529 | ||
f68d67cf | 530 | klp_init_func_early(obj, func); |
e1452b60 JB |
531 | /* |
532 | * func->new_func is same as func->old_func. These addresses are | |
533 | * set when the object is loaded, see klp_init_object_loaded(). | |
534 | */ | |
535 | func->old_sympos = old_func->old_sympos; | |
536 | func->nop = true; | |
537 | ||
538 | return func; | |
539 | } | |
540 | ||
541 | static int klp_add_object_nops(struct klp_patch *patch, | |
542 | struct klp_object *old_obj) | |
543 | { | |
544 | struct klp_object *obj; | |
545 | struct klp_func *func, *old_func; | |
546 | ||
547 | obj = klp_find_object(patch, old_obj); | |
548 | ||
549 | if (!obj) { | |
f68d67cf | 550 | obj = klp_alloc_object_dynamic(old_obj->name, patch); |
e1452b60 JB |
551 | if (!obj) |
552 | return -ENOMEM; | |
e1452b60 JB |
553 | } |
554 | ||
555 | klp_for_each_func(old_obj, old_func) { | |
556 | func = klp_find_func(obj, old_func); | |
557 | if (func) | |
558 | continue; | |
559 | ||
560 | func = klp_alloc_func_nop(old_func, obj); | |
561 | if (!func) | |
562 | return -ENOMEM; | |
e1452b60 JB |
563 | } |
564 | ||
565 | return 0; | |
566 | } | |
567 | ||
568 | /* | |
569 | * Add 'nop' functions which simply return to the caller to run | |
570 | * the original function. The 'nop' functions are added to a | |
571 | * patch to facilitate a 'replace' mode. | |
572 | */ | |
573 | static int klp_add_nops(struct klp_patch *patch) | |
574 | { | |
575 | struct klp_patch *old_patch; | |
576 | struct klp_object *old_obj; | |
577 | ||
ecba29f4 | 578 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
579 | klp_for_each_object(old_patch, old_obj) { |
580 | int err; | |
581 | ||
582 | err = klp_add_object_nops(patch, old_obj); | |
583 | if (err) | |
584 | return err; | |
585 | } | |
586 | } | |
587 | ||
588 | return 0; | |
589 | } | |
590 | ||
b700e7f0 SJ |
591 | static void klp_kobj_release_patch(struct kobject *kobj) |
592 | { | |
3ec24776 JP |
593 | struct klp_patch *patch; |
594 | ||
595 | patch = container_of(kobj, struct klp_patch, kobj); | |
596 | complete(&patch->finish); | |
b700e7f0 SJ |
597 | } |
598 | ||
1b47b80e | 599 | static const struct kobj_type klp_ktype_patch = { |
b700e7f0 SJ |
600 | .release = klp_kobj_release_patch, |
601 | .sysfs_ops = &kobj_sysfs_ops, | |
70283454 | 602 | .default_groups = klp_patch_groups, |
b700e7f0 SJ |
603 | }; |
604 | ||
cad706df MB |
605 | static void klp_kobj_release_object(struct kobject *kobj) |
606 | { | |
e1452b60 JB |
607 | struct klp_object *obj; |
608 | ||
609 | obj = container_of(kobj, struct klp_object, kobj); | |
610 | ||
611 | if (obj->dynamic) | |
612 | klp_free_object_dynamic(obj); | |
cad706df MB |
613 | } |
614 | ||
1b47b80e | 615 | static const struct kobj_type klp_ktype_object = { |
cad706df MB |
616 | .release = klp_kobj_release_object, |
617 | .sysfs_ops = &kobj_sysfs_ops, | |
bb26cfd9 | 618 | .default_groups = klp_object_groups, |
cad706df MB |
619 | }; |
620 | ||
b700e7f0 SJ |
621 | static void klp_kobj_release_func(struct kobject *kobj) |
622 | { | |
e1452b60 JB |
623 | struct klp_func *func; |
624 | ||
625 | func = container_of(kobj, struct klp_func, kobj); | |
626 | ||
627 | if (func->nop) | |
628 | klp_free_func_nop(func); | |
b700e7f0 SJ |
629 | } |
630 | ||
1b47b80e | 631 | static const struct kobj_type klp_ktype_func = { |
b700e7f0 SJ |
632 | .release = klp_kobj_release_func, |
633 | .sysfs_ops = &kobj_sysfs_ops, | |
634 | }; | |
635 | ||
d697bad5 | 636 | static void __klp_free_funcs(struct klp_object *obj, bool nops_only) |
b700e7f0 | 637 | { |
e1452b60 | 638 | struct klp_func *func, *tmp_func; |
b700e7f0 | 639 | |
e1452b60 | 640 | klp_for_each_func_safe(obj, func, tmp_func) { |
d697bad5 PM |
641 | if (nops_only && !func->nop) |
642 | continue; | |
643 | ||
644 | list_del(&func->node); | |
4d141ab3 | 645 | kobject_put(&func->kobj); |
0430f78b | 646 | } |
b700e7f0 SJ |
647 | } |
648 | ||
649 | /* Clean up when a patched object is unloaded */ | |
650 | static void klp_free_object_loaded(struct klp_object *obj) | |
651 | { | |
652 | struct klp_func *func; | |
653 | ||
654 | obj->mod = NULL; | |
655 | ||
e1452b60 | 656 | klp_for_each_func(obj, func) { |
19514910 | 657 | func->old_func = NULL; |
e1452b60 JB |
658 | |
659 | if (func->nop) | |
660 | func->new_func = NULL; | |
661 | } | |
b700e7f0 SJ |
662 | } |
663 | ||
d697bad5 | 664 | static void __klp_free_objects(struct klp_patch *patch, bool nops_only) |
b700e7f0 | 665 | { |
e1452b60 | 666 | struct klp_object *obj, *tmp_obj; |
b700e7f0 | 667 | |
e1452b60 | 668 | klp_for_each_object_safe(patch, obj, tmp_obj) { |
d697bad5 PM |
669 | __klp_free_funcs(obj, nops_only); |
670 | ||
671 | if (nops_only && !obj->dynamic) | |
672 | continue; | |
673 | ||
674 | list_del(&obj->node); | |
4d141ab3 | 675 | kobject_put(&obj->kobj); |
b700e7f0 SJ |
676 | } |
677 | } | |
678 | ||
d697bad5 PM |
679 | static void klp_free_objects(struct klp_patch *patch) |
680 | { | |
681 | __klp_free_objects(patch, false); | |
682 | } | |
683 | ||
684 | static void klp_free_objects_dynamic(struct klp_patch *patch) | |
685 | { | |
686 | __klp_free_objects(patch, true); | |
687 | } | |
688 | ||
0430f78b PM |
689 | /* |
690 | * This function implements the free operations that can be called safely | |
691 | * under klp_mutex. | |
692 | * | |
693 | * The operation must be completed by calling klp_free_patch_finish() | |
694 | * outside klp_mutex. | |
695 | */ | |
7e35e4eb | 696 | static void klp_free_patch_start(struct klp_patch *patch) |
b700e7f0 | 697 | { |
b700e7f0 SJ |
698 | if (!list_empty(&patch->list)) |
699 | list_del(&patch->list); | |
0430f78b PM |
700 | |
701 | klp_free_objects(patch); | |
702 | } | |
703 | ||
704 | /* | |
705 | * This function implements the free part that must be called outside | |
706 | * klp_mutex. | |
707 | * | |
708 | * It must be called after klp_free_patch_start(). And it has to be | |
709 | * the last function accessing the livepatch structures when the patch | |
710 | * gets disabled. | |
711 | */ | |
712 | static void klp_free_patch_finish(struct klp_patch *patch) | |
713 | { | |
714 | /* | |
715 | * Avoid deadlock with enabled_store() sysfs callback by | |
716 | * calling this outside klp_mutex. It is safe because | |
717 | * this is called when the patch gets disabled and it | |
718 | * cannot get enabled again. | |
719 | */ | |
4d141ab3 PM |
720 | kobject_put(&patch->kobj); |
721 | wait_for_completion(&patch->finish); | |
958ef1e3 PM |
722 | |
723 | /* Put the module after the last access to struct klp_patch. */ | |
724 | if (!patch->forced) | |
725 | module_put(patch->mod); | |
726 | } | |
727 | ||
728 | /* | |
729 | * The livepatch might be freed from sysfs interface created by the patch. | |
730 | * This work allows to wait until the interface is destroyed in a separate | |
731 | * context. | |
732 | */ | |
733 | static void klp_free_patch_work_fn(struct work_struct *work) | |
734 | { | |
735 | struct klp_patch *patch = | |
736 | container_of(work, struct klp_patch, free_work); | |
737 | ||
738 | klp_free_patch_finish(patch); | |
b700e7f0 SJ |
739 | } |
740 | ||
7e35e4eb PM |
741 | void klp_free_patch_async(struct klp_patch *patch) |
742 | { | |
743 | klp_free_patch_start(patch); | |
744 | schedule_work(&patch->free_work); | |
745 | } | |
746 | ||
747 | void klp_free_replaced_patches_async(struct klp_patch *new_patch) | |
748 | { | |
749 | struct klp_patch *old_patch, *tmp_patch; | |
750 | ||
751 | klp_for_each_patch_safe(old_patch, tmp_patch) { | |
752 | if (old_patch == new_patch) | |
753 | return; | |
754 | klp_free_patch_async(old_patch); | |
755 | } | |
756 | } | |
757 | ||
b700e7f0 SJ |
758 | static int klp_init_func(struct klp_object *obj, struct klp_func *func) |
759 | { | |
e1452b60 JB |
760 | if (!func->old_name) |
761 | return -EINVAL; | |
762 | ||
763 | /* | |
764 | * NOPs get the address later. The patched module must be loaded, | |
765 | * see klp_init_object_loaded(). | |
766 | */ | |
767 | if (!func->new_func && !func->nop) | |
f09d9086 MB |
768 | return -EINVAL; |
769 | ||
6e9df95b KB |
770 | if (strlen(func->old_name) >= KSYM_NAME_LEN) |
771 | return -EINVAL; | |
772 | ||
3c33f5b9 | 773 | INIT_LIST_HEAD(&func->stack_node); |
0dade9f3 | 774 | func->patched = false; |
d83a7cb3 | 775 | func->transition = false; |
b700e7f0 | 776 | |
444f9e99 CA |
777 | /* The format for the sysfs directory is <function,sympos> where sympos |
778 | * is the nth occurrence of this symbol in kallsyms for the patched | |
779 | * object. If the user selects 0 for old_sympos, then 1 will be used | |
780 | * since a unique symbol will be the first occurrence. | |
781 | */ | |
4d141ab3 PM |
782 | return kobject_add(&func->kobj, &obj->kobj, "%s,%lu", |
783 | func->old_name, | |
784 | func->old_sympos ? func->old_sympos : 1); | |
b700e7f0 SJ |
785 | } |
786 | ||
0c05e7bd SL |
787 | static int klp_write_object_relocs(struct klp_patch *patch, |
788 | struct klp_object *obj, | |
789 | bool apply) | |
7c8e2bdd JP |
790 | { |
791 | int i, ret; | |
792 | struct klp_modinfo *info = patch->mod->klp_info; | |
793 | ||
794 | for (i = 1; i < info->hdr.e_shnum; i++) { | |
795 | Elf_Shdr *sec = info->sechdrs + i; | |
796 | ||
797 | if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) | |
798 | continue; | |
799 | ||
0c05e7bd | 800 | ret = klp_write_section_relocs(patch->mod, info->sechdrs, |
7c8e2bdd JP |
801 | info->secstrings, |
802 | patch->mod->core_kallsyms.strtab, | |
0c05e7bd | 803 | info->symndx, i, obj->name, apply); |
7c8e2bdd JP |
804 | if (ret) |
805 | return ret; | |
806 | } | |
807 | ||
808 | return 0; | |
809 | } | |
810 | ||
0c05e7bd SL |
811 | static int klp_apply_object_relocs(struct klp_patch *patch, |
812 | struct klp_object *obj) | |
813 | { | |
814 | return klp_write_object_relocs(patch, obj, true); | |
815 | } | |
816 | ||
817 | static void klp_clear_object_relocs(struct klp_patch *patch, | |
818 | struct klp_object *obj) | |
819 | { | |
820 | klp_write_object_relocs(patch, obj, false); | |
821 | } | |
822 | ||
b700e7f0 SJ |
823 | /* parts of the initialization that is done only when the object is loaded */ |
824 | static int klp_init_object_loaded(struct klp_patch *patch, | |
825 | struct klp_object *obj) | |
826 | { | |
827 | struct klp_func *func; | |
828 | int ret; | |
829 | ||
7c8e2bdd JP |
830 | if (klp_is_module(obj)) { |
831 | /* | |
832 | * Only write module-specific relocations here | |
833 | * (.klp.rela.{module}.*). vmlinux-specific relocations were | |
834 | * written earlier during the initialization of the klp module | |
835 | * itself. | |
836 | */ | |
837 | ret = klp_apply_object_relocs(patch, obj); | |
1d05334d PZ |
838 | if (ret) |
839 | return ret; | |
840 | } | |
9f255b63 | 841 | |
8cdd043a | 842 | klp_for_each_func(obj, func) { |
b2b018ef CA |
843 | ret = klp_find_object_symbol(obj->name, func->old_name, |
844 | func->old_sympos, | |
19514910 | 845 | (unsigned long *)&func->old_func); |
b700e7f0 SJ |
846 | if (ret) |
847 | return ret; | |
f5e547f4 | 848 | |
19514910 | 849 | ret = kallsyms_lookup_size_offset((unsigned long)func->old_func, |
f5e547f4 JP |
850 | &func->old_size, NULL); |
851 | if (!ret) { | |
852 | pr_err("kallsyms size lookup failed for '%s'\n", | |
853 | func->old_name); | |
854 | return -ENOENT; | |
855 | } | |
856 | ||
e1452b60 JB |
857 | if (func->nop) |
858 | func->new_func = func->old_func; | |
859 | ||
f5e547f4 JP |
860 | ret = kallsyms_lookup_size_offset((unsigned long)func->new_func, |
861 | &func->new_size, NULL); | |
862 | if (!ret) { | |
863 | pr_err("kallsyms size lookup failed for '%s' replacement\n", | |
864 | func->old_name); | |
865 | return -ENOENT; | |
866 | } | |
b700e7f0 SJ |
867 | } |
868 | ||
869 | return 0; | |
870 | } | |
871 | ||
872 | static int klp_init_object(struct klp_patch *patch, struct klp_object *obj) | |
873 | { | |
874 | struct klp_func *func; | |
875 | int ret; | |
876 | const char *name; | |
877 | ||
6e9df95b KB |
878 | if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN) |
879 | return -EINVAL; | |
880 | ||
0dade9f3 | 881 | obj->patched = false; |
8cb2c2dc | 882 | obj->mod = NULL; |
b700e7f0 SJ |
883 | |
884 | klp_find_object_module(obj); | |
885 | ||
886 | name = klp_is_module(obj) ? obj->name : "vmlinux"; | |
4d141ab3 | 887 | ret = kobject_add(&obj->kobj, &patch->kobj, "%s", name); |
cad706df MB |
888 | if (ret) |
889 | return ret; | |
b700e7f0 | 890 | |
8cdd043a | 891 | klp_for_each_func(obj, func) { |
b700e7f0 SJ |
892 | ret = klp_init_func(obj, func); |
893 | if (ret) | |
0430f78b | 894 | return ret; |
b700e7f0 SJ |
895 | } |
896 | ||
0430f78b | 897 | if (klp_is_object_loaded(obj)) |
b700e7f0 | 898 | ret = klp_init_object_loaded(patch, obj); |
b700e7f0 | 899 | |
b700e7f0 SJ |
900 | return ret; |
901 | } | |
902 | ||
f68d67cf PM |
903 | static void klp_init_func_early(struct klp_object *obj, |
904 | struct klp_func *func) | |
905 | { | |
906 | kobject_init(&func->kobj, &klp_ktype_func); | |
907 | list_add_tail(&func->node, &obj->func_list); | |
908 | } | |
909 | ||
910 | static void klp_init_object_early(struct klp_patch *patch, | |
911 | struct klp_object *obj) | |
912 | { | |
913 | INIT_LIST_HEAD(&obj->func_list); | |
914 | kobject_init(&obj->kobj, &klp_ktype_object); | |
915 | list_add_tail(&obj->node, &patch->obj_list); | |
916 | } | |
917 | ||
5ef3dd20 | 918 | static void klp_init_patch_early(struct klp_patch *patch) |
b700e7f0 SJ |
919 | { |
920 | struct klp_object *obj; | |
0430f78b | 921 | struct klp_func *func; |
b700e7f0 | 922 | |
0430f78b | 923 | INIT_LIST_HEAD(&patch->list); |
20e55025 | 924 | INIT_LIST_HEAD(&patch->obj_list); |
4d141ab3 | 925 | kobject_init(&patch->kobj, &klp_ktype_patch); |
0dade9f3 | 926 | patch->enabled = false; |
68007289 | 927 | patch->forced = false; |
958ef1e3 | 928 | INIT_WORK(&patch->free_work, klp_free_patch_work_fn); |
3ec24776 | 929 | init_completion(&patch->finish); |
b700e7f0 | 930 | |
20e55025 | 931 | klp_for_each_object_static(patch, obj) { |
f68d67cf | 932 | klp_init_object_early(patch, obj); |
0430f78b | 933 | |
20e55025 | 934 | klp_for_each_func_static(obj, func) { |
f68d67cf | 935 | klp_init_func_early(obj, func); |
20e55025 | 936 | } |
0430f78b | 937 | } |
0430f78b PM |
938 | } |
939 | ||
940 | static int klp_init_patch(struct klp_patch *patch) | |
941 | { | |
942 | struct klp_object *obj; | |
943 | int ret; | |
944 | ||
4d141ab3 | 945 | ret = kobject_add(&patch->kobj, klp_root_kobj, "%s", patch->mod->name); |
958ef1e3 | 946 | if (ret) |
3ec24776 | 947 | return ret; |
b700e7f0 | 948 | |
e1452b60 JB |
949 | if (patch->replace) { |
950 | ret = klp_add_nops(patch); | |
951 | if (ret) | |
952 | return ret; | |
953 | } | |
954 | ||
8cdd043a | 955 | klp_for_each_object(patch, obj) { |
b700e7f0 SJ |
956 | ret = klp_init_object(patch, obj); |
957 | if (ret) | |
958ef1e3 | 958 | return ret; |
b700e7f0 SJ |
959 | } |
960 | ||
99590ba5 | 961 | list_add_tail(&patch->list, &klp_patches); |
b700e7f0 | 962 | |
3ec24776 | 963 | return 0; |
b700e7f0 | 964 | } |
b700e7f0 | 965 | |
26c3e98e PM |
966 | static int __klp_disable_patch(struct klp_patch *patch) |
967 | { | |
968 | struct klp_object *obj; | |
969 | ||
970 | if (WARN_ON(!patch->enabled)) | |
971 | return -EINVAL; | |
972 | ||
973 | if (klp_transition_patch) | |
974 | return -EBUSY; | |
975 | ||
26c3e98e PM |
976 | klp_init_transition(patch, KLP_UNPATCHED); |
977 | ||
978 | klp_for_each_object(patch, obj) | |
979 | if (obj->patched) | |
980 | klp_pre_unpatch_callback(obj); | |
981 | ||
982 | /* | |
983 | * Enforce the order of the func->transition writes in | |
984 | * klp_init_transition() and the TIF_PATCH_PENDING writes in | |
985 | * klp_start_transition(). In the rare case where klp_ftrace_handler() | |
986 | * is called shortly after klp_update_patch_state() switches the task, | |
987 | * this ensures the handler sees that func->transition is set. | |
988 | */ | |
989 | smp_wmb(); | |
990 | ||
991 | klp_start_transition(); | |
26c3e98e | 992 | patch->enabled = false; |
958ef1e3 | 993 | klp_try_complete_transition(); |
26c3e98e PM |
994 | |
995 | return 0; | |
996 | } | |
997 | ||
26c3e98e PM |
998 | static int __klp_enable_patch(struct klp_patch *patch) |
999 | { | |
1000 | struct klp_object *obj; | |
1001 | int ret; | |
1002 | ||
1003 | if (klp_transition_patch) | |
1004 | return -EBUSY; | |
1005 | ||
1006 | if (WARN_ON(patch->enabled)) | |
1007 | return -EINVAL; | |
1008 | ||
26c3e98e PM |
1009 | pr_notice("enabling patch '%s'\n", patch->mod->name); |
1010 | ||
1011 | klp_init_transition(patch, KLP_PATCHED); | |
1012 | ||
1013 | /* | |
1014 | * Enforce the order of the func->transition writes in | |
1015 | * klp_init_transition() and the ops->func_stack writes in | |
1016 | * klp_patch_object(), so that klp_ftrace_handler() will see the | |
1017 | * func->transition updates before the handler is registered and the | |
1018 | * new funcs become visible to the handler. | |
1019 | */ | |
1020 | smp_wmb(); | |
1021 | ||
1022 | klp_for_each_object(patch, obj) { | |
1023 | if (!klp_is_object_loaded(obj)) | |
1024 | continue; | |
1025 | ||
1026 | ret = klp_pre_patch_callback(obj); | |
1027 | if (ret) { | |
1028 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1029 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
1030 | goto err; | |
1031 | } | |
1032 | ||
1033 | ret = klp_patch_object(obj); | |
1034 | if (ret) { | |
1035 | pr_warn("failed to patch object '%s'\n", | |
1036 | klp_is_module(obj) ? obj->name : "vmlinux"); | |
1037 | goto err; | |
1038 | } | |
1039 | } | |
1040 | ||
1041 | klp_start_transition(); | |
26c3e98e | 1042 | patch->enabled = true; |
958ef1e3 | 1043 | klp_try_complete_transition(); |
26c3e98e PM |
1044 | |
1045 | return 0; | |
1046 | err: | |
1047 | pr_warn("failed to enable patch '%s'\n", patch->mod->name); | |
1048 | ||
1049 | klp_cancel_transition(); | |
1050 | return ret; | |
1051 | } | |
1052 | ||
1053 | /** | |
958ef1e3 PM |
1054 | * klp_enable_patch() - enable the livepatch |
1055 | * @patch: patch to be enabled | |
26c3e98e | 1056 | * |
958ef1e3 PM |
1057 | * Initializes the data structure associated with the patch, creates the sysfs |
1058 | * interface, performs the needed symbol lookups and code relocations, | |
1059 | * registers the patched functions with ftrace. | |
1060 | * | |
1061 | * This function is supposed to be called from the livepatch module_init() | |
1062 | * callback. | |
26c3e98e PM |
1063 | * |
1064 | * Return: 0 on success, otherwise error | |
1065 | */ | |
1066 | int klp_enable_patch(struct klp_patch *patch) | |
1067 | { | |
1068 | int ret; | |
5ef3dd20 | 1069 | struct klp_object *obj; |
26c3e98e | 1070 | |
5ef3dd20 | 1071 | if (!patch || !patch->mod || !patch->objs) |
958ef1e3 PM |
1072 | return -EINVAL; |
1073 | ||
5ef3dd20 DV |
1074 | klp_for_each_object_static(patch, obj) { |
1075 | if (!obj->funcs) | |
1076 | return -EINVAL; | |
1077 | } | |
1078 | ||
1079 | ||
958ef1e3 PM |
1080 | if (!is_livepatch_module(patch->mod)) { |
1081 | pr_err("module %s is not marked as a livepatch module\n", | |
1082 | patch->mod->name); | |
1083 | return -EINVAL; | |
1084 | } | |
1085 | ||
1086 | if (!klp_initialized()) | |
1087 | return -ENODEV; | |
1088 | ||
1089 | if (!klp_have_reliable_stack()) { | |
31adf230 PM |
1090 | pr_warn("This architecture doesn't have support for the livepatch consistency model.\n"); |
1091 | pr_warn("The livepatch transition may never complete.\n"); | |
958ef1e3 PM |
1092 | } |
1093 | ||
26c3e98e PM |
1094 | mutex_lock(&klp_mutex); |
1095 | ||
92c9abf5 PM |
1096 | if (!klp_is_patch_compatible(patch)) { |
1097 | pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n", | |
1098 | patch->mod->name); | |
1099 | mutex_unlock(&klp_mutex); | |
1100 | return -EINVAL; | |
1101 | } | |
1102 | ||
50a0f3f5 YY |
1103 | if (!try_module_get(patch->mod)) { |
1104 | mutex_unlock(&klp_mutex); | |
5ef3dd20 | 1105 | return -ENODEV; |
50a0f3f5 | 1106 | } |
5ef3dd20 DV |
1107 | |
1108 | klp_init_patch_early(patch); | |
26c3e98e | 1109 | |
958ef1e3 PM |
1110 | ret = klp_init_patch(patch); |
1111 | if (ret) | |
1112 | goto err; | |
1113 | ||
26c3e98e | 1114 | ret = __klp_enable_patch(patch); |
958ef1e3 PM |
1115 | if (ret) |
1116 | goto err; | |
1117 | ||
1118 | mutex_unlock(&klp_mutex); | |
1119 | ||
1120 | return 0; | |
26c3e98e PM |
1121 | |
1122 | err: | |
958ef1e3 PM |
1123 | klp_free_patch_start(patch); |
1124 | ||
26c3e98e | 1125 | mutex_unlock(&klp_mutex); |
958ef1e3 PM |
1126 | |
1127 | klp_free_patch_finish(patch); | |
1128 | ||
26c3e98e PM |
1129 | return ret; |
1130 | } | |
1131 | EXPORT_SYMBOL_GPL(klp_enable_patch); | |
1132 | ||
e1452b60 | 1133 | /* |
7e35e4eb | 1134 | * This function unpatches objects from the replaced livepatches. |
e1452b60 JB |
1135 | * |
1136 | * We could be pretty aggressive here. It is called in the situation where | |
7e35e4eb PM |
1137 | * these structures are no longer accessed from the ftrace handler. |
1138 | * All functions are redirected by the klp_transition_patch. They | |
1139 | * use either a new code or they are in the original code because | |
1140 | * of the special nop function patches. | |
e1452b60 JB |
1141 | * |
1142 | * The only exception is when the transition was forced. In this case, | |
1143 | * klp_ftrace_handler() might still see the replaced patch on the stack. | |
1144 | * Fortunately, it is carefully designed to work with removed functions | |
1145 | * thanks to RCU. We only have to keep the patches on the system. Also | |
1146 | * this is handled transparently by patch->module_put. | |
1147 | */ | |
7e35e4eb | 1148 | void klp_unpatch_replaced_patches(struct klp_patch *new_patch) |
e1452b60 | 1149 | { |
7e35e4eb | 1150 | struct klp_patch *old_patch; |
e1452b60 | 1151 | |
7e35e4eb | 1152 | klp_for_each_patch(old_patch) { |
e1452b60 JB |
1153 | if (old_patch == new_patch) |
1154 | return; | |
1155 | ||
1156 | old_patch->enabled = false; | |
1157 | klp_unpatch_objects(old_patch); | |
e1452b60 JB |
1158 | } |
1159 | } | |
1160 | ||
d697bad5 PM |
1161 | /* |
1162 | * This function removes the dynamically allocated 'nop' functions. | |
1163 | * | |
1164 | * We could be pretty aggressive. NOPs do not change the existing | |
1165 | * behavior except for adding unnecessary delay by the ftrace handler. | |
1166 | * | |
1167 | * It is safe even when the transition was forced. The ftrace handler | |
1168 | * will see a valid ops->func_stack entry thanks to RCU. | |
1169 | * | |
1170 | * We could even free the NOPs structures. They must be the last entry | |
1171 | * in ops->func_stack. Therefore unregister_ftrace_function() is called. | |
1172 | * It does the same as klp_synchronize_transition() to make sure that | |
1173 | * nobody is inside the ftrace handler once the operation finishes. | |
1174 | * | |
1175 | * IMPORTANT: It must be called right after removing the replaced patches! | |
1176 | */ | |
1177 | void klp_discard_nops(struct klp_patch *new_patch) | |
1178 | { | |
1179 | klp_unpatch_objects_dynamic(klp_transition_patch); | |
1180 | klp_free_objects_dynamic(klp_transition_patch); | |
1181 | } | |
1182 | ||
ef8daf8e JL |
1183 | /* |
1184 | * Remove parts of patches that touch a given kernel module. The list of | |
1185 | * patches processed might be limited. When limit is NULL, all patches | |
1186 | * will be handled. | |
1187 | */ | |
1188 | static void klp_cleanup_module_patches_limited(struct module *mod, | |
1189 | struct klp_patch *limit) | |
1190 | { | |
1191 | struct klp_patch *patch; | |
1192 | struct klp_object *obj; | |
1193 | ||
ecba29f4 | 1194 | klp_for_each_patch(patch) { |
ef8daf8e JL |
1195 | if (patch == limit) |
1196 | break; | |
1197 | ||
1198 | klp_for_each_object(patch, obj) { | |
1199 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1200 | continue; | |
1201 | ||
a087cdd4 PM |
1202 | if (patch != klp_transition_patch) |
1203 | klp_pre_unpatch_callback(obj); | |
fc41efc1 | 1204 | |
a087cdd4 PM |
1205 | pr_notice("reverting patch '%s' on unloading module '%s'\n", |
1206 | patch->mod->name, obj->mod->name); | |
1207 | klp_unpatch_object(obj); | |
fc41efc1 | 1208 | |
a087cdd4 | 1209 | klp_post_unpatch_callback(obj); |
0c05e7bd | 1210 | klp_clear_object_relocs(patch, obj); |
ef8daf8e JL |
1211 | klp_free_object_loaded(obj); |
1212 | break; | |
1213 | } | |
1214 | } | |
1215 | } | |
1216 | ||
7e545d6e | 1217 | int klp_module_coming(struct module *mod) |
b700e7f0 | 1218 | { |
b700e7f0 | 1219 | int ret; |
7e545d6e JY |
1220 | struct klp_patch *patch; |
1221 | struct klp_object *obj; | |
b700e7f0 | 1222 | |
7e545d6e JY |
1223 | if (WARN_ON(mod->state != MODULE_STATE_COMING)) |
1224 | return -EINVAL; | |
b700e7f0 | 1225 | |
dcf550e5 | 1226 | if (!strcmp(mod->name, "vmlinux")) { |
66d8529d | 1227 | pr_err("vmlinux.ko: invalid module name\n"); |
dcf550e5 JP |
1228 | return -EINVAL; |
1229 | } | |
1230 | ||
7e545d6e JY |
1231 | mutex_lock(&klp_mutex); |
1232 | /* | |
1233 | * Each module has to know that klp_module_coming() | |
1234 | * has been called. We never know what module will | |
1235 | * get patched by a new patch. | |
1236 | */ | |
1237 | mod->klp_alive = true; | |
b700e7f0 | 1238 | |
ecba29f4 | 1239 | klp_for_each_patch(patch) { |
7e545d6e JY |
1240 | klp_for_each_object(patch, obj) { |
1241 | if (!klp_is_module(obj) || strcmp(obj->name, mod->name)) | |
1242 | continue; | |
b700e7f0 | 1243 | |
7e545d6e | 1244 | obj->mod = mod; |
b700e7f0 | 1245 | |
7e545d6e JY |
1246 | ret = klp_init_object_loaded(patch, obj); |
1247 | if (ret) { | |
1248 | pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n", | |
1249 | patch->mod->name, obj->mod->name, ret); | |
1250 | goto err; | |
1251 | } | |
b700e7f0 | 1252 | |
7e545d6e JY |
1253 | pr_notice("applying patch '%s' to loading module '%s'\n", |
1254 | patch->mod->name, obj->mod->name); | |
1255 | ||
93862e38 JL |
1256 | ret = klp_pre_patch_callback(obj); |
1257 | if (ret) { | |
1258 | pr_warn("pre-patch callback failed for object '%s'\n", | |
1259 | obj->name); | |
1260 | goto err; | |
1261 | } | |
1262 | ||
0dade9f3 | 1263 | ret = klp_patch_object(obj); |
7e545d6e JY |
1264 | if (ret) { |
1265 | pr_warn("failed to apply patch '%s' to module '%s' (%d)\n", | |
1266 | patch->mod->name, obj->mod->name, ret); | |
93862e38 | 1267 | |
5aaf1ab5 | 1268 | klp_post_unpatch_callback(obj); |
7e545d6e JY |
1269 | goto err; |
1270 | } | |
1271 | ||
93862e38 JL |
1272 | if (patch != klp_transition_patch) |
1273 | klp_post_patch_callback(obj); | |
1274 | ||
7e545d6e JY |
1275 | break; |
1276 | } | |
1277 | } | |
b700e7f0 | 1278 | |
7e545d6e | 1279 | mutex_unlock(&klp_mutex); |
b700e7f0 | 1280 | |
7e545d6e | 1281 | return 0; |
b700e7f0 | 1282 | |
7e545d6e JY |
1283 | err: |
1284 | /* | |
1285 | * If a patch is unsuccessfully applied, return | |
1286 | * error to the module loader. | |
1287 | */ | |
1288 | pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n", | |
1289 | patch->mod->name, obj->mod->name, obj->mod->name); | |
1290 | mod->klp_alive = false; | |
4ff96fb5 | 1291 | obj->mod = NULL; |
ef8daf8e | 1292 | klp_cleanup_module_patches_limited(mod, patch); |
7e545d6e JY |
1293 | mutex_unlock(&klp_mutex); |
1294 | ||
1295 | return ret; | |
b700e7f0 SJ |
1296 | } |
1297 | ||
7e545d6e | 1298 | void klp_module_going(struct module *mod) |
b700e7f0 | 1299 | { |
7e545d6e JY |
1300 | if (WARN_ON(mod->state != MODULE_STATE_GOING && |
1301 | mod->state != MODULE_STATE_COMING)) | |
1302 | return; | |
b700e7f0 SJ |
1303 | |
1304 | mutex_lock(&klp_mutex); | |
8cb2c2dc | 1305 | /* |
7e545d6e JY |
1306 | * Each module has to know that klp_module_going() |
1307 | * has been called. We never know what module will | |
1308 | * get patched by a new patch. | |
8cb2c2dc | 1309 | */ |
7e545d6e | 1310 | mod->klp_alive = false; |
8cb2c2dc | 1311 | |
ef8daf8e | 1312 | klp_cleanup_module_patches_limited(mod, NULL); |
b700e7f0 SJ |
1313 | |
1314 | mutex_unlock(&klp_mutex); | |
b700e7f0 SJ |
1315 | } |
1316 | ||
26029d88 | 1317 | static int __init klp_init(void) |
b700e7f0 | 1318 | { |
b700e7f0 | 1319 | klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj); |
7e545d6e JY |
1320 | if (!klp_root_kobj) |
1321 | return -ENOMEM; | |
b700e7f0 SJ |
1322 | |
1323 | return 0; | |
b700e7f0 SJ |
1324 | } |
1325 | ||
1326 | module_init(klp_init); |