| 1 | /* |
| 2 | * Kernel Probes (KProbes) |
| 3 | * kernel/kprobes.c |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 18 | * |
| 19 | * Copyright (C) IBM Corporation, 2002, 2004 |
| 20 | * |
| 21 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel |
| 22 | * Probes initial implementation (includes suggestions from |
| 23 | * Rusty Russell). |
| 24 | * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with |
| 25 | * hlists and exceptions notifier as suggested by Andi Kleen. |
| 26 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes |
| 27 | * interface to access function arguments. |
| 28 | * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes |
| 29 | * exceptions notifier to be first on the priority list. |
| 30 | * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston |
| 31 | * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi |
| 32 | * <prasanna@in.ibm.com> added function-return probes. |
| 33 | */ |
| 34 | #include <linux/kprobes.h> |
| 35 | #include <linux/hash.h> |
| 36 | #include <linux/init.h> |
| 37 | #include <linux/slab.h> |
| 38 | #include <linux/stddef.h> |
| 39 | #include <linux/module.h> |
| 40 | #include <linux/moduleloader.h> |
| 41 | #include <linux/kallsyms.h> |
| 42 | #include <linux/freezer.h> |
| 43 | #include <linux/seq_file.h> |
| 44 | #include <linux/debugfs.h> |
| 45 | #include <linux/kdebug.h> |
| 46 | |
| 47 | #include <asm-generic/sections.h> |
| 48 | #include <asm/cacheflush.h> |
| 49 | #include <asm/errno.h> |
| 50 | #include <asm/uaccess.h> |
| 51 | |
| 52 | #define KPROBE_HASH_BITS 6 |
| 53 | #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) |
| 54 | |
| 55 | |
| 56 | /* |
| 57 | * Some oddball architectures like 64bit powerpc have function descriptors |
| 58 | * so this must be overridable. |
| 59 | */ |
| 60 | #ifndef kprobe_lookup_name |
| 61 | #define kprobe_lookup_name(name, addr) \ |
| 62 | addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name))) |
| 63 | #endif |
| 64 | |
| 65 | static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; |
| 66 | static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; |
| 67 | |
| 68 | /* NOTE: change this value only with kprobe_mutex held */ |
| 69 | static bool kprobe_enabled; |
| 70 | |
| 71 | DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ |
| 72 | DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */ |
| 73 | static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; |
| 74 | |
| 75 | #ifdef __ARCH_WANT_KPROBES_INSN_SLOT |
| 76 | /* |
| 77 | * kprobe->ainsn.insn points to the copy of the instruction to be |
| 78 | * single-stepped. x86_64, POWER4 and above have no-exec support and |
| 79 | * stepping on the instruction on a vmalloced/kmalloced/data page |
| 80 | * is a recipe for disaster |
| 81 | */ |
| 82 | #define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) |
| 83 | |
| 84 | struct kprobe_insn_page { |
| 85 | struct hlist_node hlist; |
| 86 | kprobe_opcode_t *insns; /* Page of instruction slots */ |
| 87 | char slot_used[INSNS_PER_PAGE]; |
| 88 | int nused; |
| 89 | int ngarbage; |
| 90 | }; |
| 91 | |
| 92 | enum kprobe_slot_state { |
| 93 | SLOT_CLEAN = 0, |
| 94 | SLOT_DIRTY = 1, |
| 95 | SLOT_USED = 2, |
| 96 | }; |
| 97 | |
| 98 | static struct hlist_head kprobe_insn_pages; |
| 99 | static int kprobe_garbage_slots; |
| 100 | static int collect_garbage_slots(void); |
| 101 | |
| 102 | static int __kprobes check_safety(void) |
| 103 | { |
| 104 | int ret = 0; |
| 105 | #if defined(CONFIG_PREEMPT) && defined(CONFIG_PM) |
| 106 | ret = freeze_processes(); |
| 107 | if (ret == 0) { |
| 108 | struct task_struct *p, *q; |
| 109 | do_each_thread(p, q) { |
| 110 | if (p != current && p->state == TASK_RUNNING && |
| 111 | p->pid != 0) { |
| 112 | printk("Check failed: %s is running\n",p->comm); |
| 113 | ret = -1; |
| 114 | goto loop_end; |
| 115 | } |
| 116 | } while_each_thread(p, q); |
| 117 | } |
| 118 | loop_end: |
| 119 | thaw_processes(); |
| 120 | #else |
| 121 | synchronize_sched(); |
| 122 | #endif |
| 123 | return ret; |
| 124 | } |
| 125 | |
| 126 | /** |
| 127 | * get_insn_slot() - Find a slot on an executable page for an instruction. |
| 128 | * We allocate an executable page if there's no room on existing ones. |
| 129 | */ |
| 130 | kprobe_opcode_t __kprobes *get_insn_slot(void) |
| 131 | { |
| 132 | struct kprobe_insn_page *kip; |
| 133 | struct hlist_node *pos; |
| 134 | |
| 135 | retry: |
| 136 | hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) { |
| 137 | if (kip->nused < INSNS_PER_PAGE) { |
| 138 | int i; |
| 139 | for (i = 0; i < INSNS_PER_PAGE; i++) { |
| 140 | if (kip->slot_used[i] == SLOT_CLEAN) { |
| 141 | kip->slot_used[i] = SLOT_USED; |
| 142 | kip->nused++; |
| 143 | return kip->insns + (i * MAX_INSN_SIZE); |
| 144 | } |
| 145 | } |
| 146 | /* Surprise! No unused slots. Fix kip->nused. */ |
| 147 | kip->nused = INSNS_PER_PAGE; |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | /* If there are any garbage slots, collect it and try again. */ |
| 152 | if (kprobe_garbage_slots && collect_garbage_slots() == 0) { |
| 153 | goto retry; |
| 154 | } |
| 155 | /* All out of space. Need to allocate a new page. Use slot 0. */ |
| 156 | kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); |
| 157 | if (!kip) |
| 158 | return NULL; |
| 159 | |
| 160 | /* |
| 161 | * Use module_alloc so this page is within +/- 2GB of where the |
| 162 | * kernel image and loaded module images reside. This is required |
| 163 | * so x86_64 can correctly handle the %rip-relative fixups. |
| 164 | */ |
| 165 | kip->insns = module_alloc(PAGE_SIZE); |
| 166 | if (!kip->insns) { |
| 167 | kfree(kip); |
| 168 | return NULL; |
| 169 | } |
| 170 | INIT_HLIST_NODE(&kip->hlist); |
| 171 | hlist_add_head(&kip->hlist, &kprobe_insn_pages); |
| 172 | memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE); |
| 173 | kip->slot_used[0] = SLOT_USED; |
| 174 | kip->nused = 1; |
| 175 | kip->ngarbage = 0; |
| 176 | return kip->insns; |
| 177 | } |
| 178 | |
| 179 | /* Return 1 if all garbages are collected, otherwise 0. */ |
| 180 | static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx) |
| 181 | { |
| 182 | kip->slot_used[idx] = SLOT_CLEAN; |
| 183 | kip->nused--; |
| 184 | if (kip->nused == 0) { |
| 185 | /* |
| 186 | * Page is no longer in use. Free it unless |
| 187 | * it's the last one. We keep the last one |
| 188 | * so as not to have to set it up again the |
| 189 | * next time somebody inserts a probe. |
| 190 | */ |
| 191 | hlist_del(&kip->hlist); |
| 192 | if (hlist_empty(&kprobe_insn_pages)) { |
| 193 | INIT_HLIST_NODE(&kip->hlist); |
| 194 | hlist_add_head(&kip->hlist, |
| 195 | &kprobe_insn_pages); |
| 196 | } else { |
| 197 | module_free(NULL, kip->insns); |
| 198 | kfree(kip); |
| 199 | } |
| 200 | return 1; |
| 201 | } |
| 202 | return 0; |
| 203 | } |
| 204 | |
| 205 | static int __kprobes collect_garbage_slots(void) |
| 206 | { |
| 207 | struct kprobe_insn_page *kip; |
| 208 | struct hlist_node *pos, *next; |
| 209 | |
| 210 | /* Ensure no-one is preepmted on the garbages */ |
| 211 | if (check_safety() != 0) |
| 212 | return -EAGAIN; |
| 213 | |
| 214 | hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) { |
| 215 | int i; |
| 216 | if (kip->ngarbage == 0) |
| 217 | continue; |
| 218 | kip->ngarbage = 0; /* we will collect all garbages */ |
| 219 | for (i = 0; i < INSNS_PER_PAGE; i++) { |
| 220 | if (kip->slot_used[i] == SLOT_DIRTY && |
| 221 | collect_one_slot(kip, i)) |
| 222 | break; |
| 223 | } |
| 224 | } |
| 225 | kprobe_garbage_slots = 0; |
| 226 | return 0; |
| 227 | } |
| 228 | |
| 229 | void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) |
| 230 | { |
| 231 | struct kprobe_insn_page *kip; |
| 232 | struct hlist_node *pos; |
| 233 | |
| 234 | hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) { |
| 235 | if (kip->insns <= slot && |
| 236 | slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) { |
| 237 | int i = (slot - kip->insns) / MAX_INSN_SIZE; |
| 238 | if (dirty) { |
| 239 | kip->slot_used[i] = SLOT_DIRTY; |
| 240 | kip->ngarbage++; |
| 241 | } else { |
| 242 | collect_one_slot(kip, i); |
| 243 | } |
| 244 | break; |
| 245 | } |
| 246 | } |
| 247 | |
| 248 | if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE) |
| 249 | collect_garbage_slots(); |
| 250 | } |
| 251 | #endif |
| 252 | |
| 253 | /* We have preemption disabled.. so it is safe to use __ versions */ |
| 254 | static inline void set_kprobe_instance(struct kprobe *kp) |
| 255 | { |
| 256 | __get_cpu_var(kprobe_instance) = kp; |
| 257 | } |
| 258 | |
| 259 | static inline void reset_kprobe_instance(void) |
| 260 | { |
| 261 | __get_cpu_var(kprobe_instance) = NULL; |
| 262 | } |
| 263 | |
| 264 | /* |
| 265 | * This routine is called either: |
| 266 | * - under the kprobe_mutex - during kprobe_[un]register() |
| 267 | * OR |
| 268 | * - with preemption disabled - from arch/xxx/kernel/kprobes.c |
| 269 | */ |
| 270 | struct kprobe __kprobes *get_kprobe(void *addr) |
| 271 | { |
| 272 | struct hlist_head *head; |
| 273 | struct hlist_node *node; |
| 274 | struct kprobe *p; |
| 275 | |
| 276 | head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; |
| 277 | hlist_for_each_entry_rcu(p, node, head, hlist) { |
| 278 | if (p->addr == addr) |
| 279 | return p; |
| 280 | } |
| 281 | return NULL; |
| 282 | } |
| 283 | |
| 284 | /* |
| 285 | * Aggregate handlers for multiple kprobes support - these handlers |
| 286 | * take care of invoking the individual kprobe handlers on p->list |
| 287 | */ |
| 288 | static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) |
| 289 | { |
| 290 | struct kprobe *kp; |
| 291 | |
| 292 | list_for_each_entry_rcu(kp, &p->list, list) { |
| 293 | if (kp->pre_handler) { |
| 294 | set_kprobe_instance(kp); |
| 295 | if (kp->pre_handler(kp, regs)) |
| 296 | return 1; |
| 297 | } |
| 298 | reset_kprobe_instance(); |
| 299 | } |
| 300 | return 0; |
| 301 | } |
| 302 | |
| 303 | static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, |
| 304 | unsigned long flags) |
| 305 | { |
| 306 | struct kprobe *kp; |
| 307 | |
| 308 | list_for_each_entry_rcu(kp, &p->list, list) { |
| 309 | if (kp->post_handler) { |
| 310 | set_kprobe_instance(kp); |
| 311 | kp->post_handler(kp, regs, flags); |
| 312 | reset_kprobe_instance(); |
| 313 | } |
| 314 | } |
| 315 | } |
| 316 | |
| 317 | static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, |
| 318 | int trapnr) |
| 319 | { |
| 320 | struct kprobe *cur = __get_cpu_var(kprobe_instance); |
| 321 | |
| 322 | /* |
| 323 | * if we faulted "during" the execution of a user specified |
| 324 | * probe handler, invoke just that probe's fault handler |
| 325 | */ |
| 326 | if (cur && cur->fault_handler) { |
| 327 | if (cur->fault_handler(cur, regs, trapnr)) |
| 328 | return 1; |
| 329 | } |
| 330 | return 0; |
| 331 | } |
| 332 | |
| 333 | static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs) |
| 334 | { |
| 335 | struct kprobe *cur = __get_cpu_var(kprobe_instance); |
| 336 | int ret = 0; |
| 337 | |
| 338 | if (cur && cur->break_handler) { |
| 339 | if (cur->break_handler(cur, regs)) |
| 340 | ret = 1; |
| 341 | } |
| 342 | reset_kprobe_instance(); |
| 343 | return ret; |
| 344 | } |
| 345 | |
| 346 | /* Walks the list and increments nmissed count for multiprobe case */ |
| 347 | void __kprobes kprobes_inc_nmissed_count(struct kprobe *p) |
| 348 | { |
| 349 | struct kprobe *kp; |
| 350 | if (p->pre_handler != aggr_pre_handler) { |
| 351 | p->nmissed++; |
| 352 | } else { |
| 353 | list_for_each_entry_rcu(kp, &p->list, list) |
| 354 | kp->nmissed++; |
| 355 | } |
| 356 | return; |
| 357 | } |
| 358 | |
| 359 | /* Called with kretprobe_lock held */ |
| 360 | void __kprobes recycle_rp_inst(struct kretprobe_instance *ri, |
| 361 | struct hlist_head *head) |
| 362 | { |
| 363 | /* remove rp inst off the rprobe_inst_table */ |
| 364 | hlist_del(&ri->hlist); |
| 365 | if (ri->rp) { |
| 366 | /* remove rp inst off the used list */ |
| 367 | hlist_del(&ri->uflist); |
| 368 | /* put rp inst back onto the free list */ |
| 369 | INIT_HLIST_NODE(&ri->uflist); |
| 370 | hlist_add_head(&ri->uflist, &ri->rp->free_instances); |
| 371 | } else |
| 372 | /* Unregistering */ |
| 373 | hlist_add_head(&ri->hlist, head); |
| 374 | } |
| 375 | |
| 376 | struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk) |
| 377 | { |
| 378 | return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]; |
| 379 | } |
| 380 | |
| 381 | /* |
| 382 | * This function is called from finish_task_switch when task tk becomes dead, |
| 383 | * so that we can recycle any function-return probe instances associated |
| 384 | * with this task. These left over instances represent probed functions |
| 385 | * that have been called but will never return. |
| 386 | */ |
| 387 | void __kprobes kprobe_flush_task(struct task_struct *tk) |
| 388 | { |
| 389 | struct kretprobe_instance *ri; |
| 390 | struct hlist_head *head, empty_rp; |
| 391 | struct hlist_node *node, *tmp; |
| 392 | unsigned long flags = 0; |
| 393 | |
| 394 | INIT_HLIST_HEAD(&empty_rp); |
| 395 | spin_lock_irqsave(&kretprobe_lock, flags); |
| 396 | head = kretprobe_inst_table_head(tk); |
| 397 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { |
| 398 | if (ri->task == tk) |
| 399 | recycle_rp_inst(ri, &empty_rp); |
| 400 | } |
| 401 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
| 402 | |
| 403 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
| 404 | hlist_del(&ri->hlist); |
| 405 | kfree(ri); |
| 406 | } |
| 407 | } |
| 408 | |
| 409 | static inline void free_rp_inst(struct kretprobe *rp) |
| 410 | { |
| 411 | struct kretprobe_instance *ri; |
| 412 | struct hlist_node *pos, *next; |
| 413 | |
| 414 | hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, uflist) { |
| 415 | hlist_del(&ri->uflist); |
| 416 | kfree(ri); |
| 417 | } |
| 418 | } |
| 419 | |
| 420 | /* |
| 421 | * Keep all fields in the kprobe consistent |
| 422 | */ |
| 423 | static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) |
| 424 | { |
| 425 | memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t)); |
| 426 | memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn)); |
| 427 | } |
| 428 | |
| 429 | /* |
| 430 | * Add the new probe to old_p->list. Fail if this is the |
| 431 | * second jprobe at the address - two jprobes can't coexist |
| 432 | */ |
| 433 | static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p) |
| 434 | { |
| 435 | if (p->break_handler) { |
| 436 | if (old_p->break_handler) |
| 437 | return -EEXIST; |
| 438 | list_add_tail_rcu(&p->list, &old_p->list); |
| 439 | old_p->break_handler = aggr_break_handler; |
| 440 | } else |
| 441 | list_add_rcu(&p->list, &old_p->list); |
| 442 | if (p->post_handler && !old_p->post_handler) |
| 443 | old_p->post_handler = aggr_post_handler; |
| 444 | return 0; |
| 445 | } |
| 446 | |
| 447 | /* |
| 448 | * Fill in the required fields of the "manager kprobe". Replace the |
| 449 | * earlier kprobe in the hlist with the manager kprobe |
| 450 | */ |
| 451 | static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) |
| 452 | { |
| 453 | copy_kprobe(p, ap); |
| 454 | flush_insn_slot(ap); |
| 455 | ap->addr = p->addr; |
| 456 | ap->pre_handler = aggr_pre_handler; |
| 457 | ap->fault_handler = aggr_fault_handler; |
| 458 | if (p->post_handler) |
| 459 | ap->post_handler = aggr_post_handler; |
| 460 | if (p->break_handler) |
| 461 | ap->break_handler = aggr_break_handler; |
| 462 | |
| 463 | INIT_LIST_HEAD(&ap->list); |
| 464 | list_add_rcu(&p->list, &ap->list); |
| 465 | |
| 466 | hlist_replace_rcu(&p->hlist, &ap->hlist); |
| 467 | } |
| 468 | |
| 469 | /* |
| 470 | * This is the second or subsequent kprobe at the address - handle |
| 471 | * the intricacies |
| 472 | */ |
| 473 | static int __kprobes register_aggr_kprobe(struct kprobe *old_p, |
| 474 | struct kprobe *p) |
| 475 | { |
| 476 | int ret = 0; |
| 477 | struct kprobe *ap; |
| 478 | |
| 479 | if (old_p->pre_handler == aggr_pre_handler) { |
| 480 | copy_kprobe(old_p, p); |
| 481 | ret = add_new_kprobe(old_p, p); |
| 482 | } else { |
| 483 | ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL); |
| 484 | if (!ap) |
| 485 | return -ENOMEM; |
| 486 | add_aggr_kprobe(ap, old_p); |
| 487 | copy_kprobe(ap, p); |
| 488 | ret = add_new_kprobe(ap, p); |
| 489 | } |
| 490 | return ret; |
| 491 | } |
| 492 | |
| 493 | static int __kprobes in_kprobes_functions(unsigned long addr) |
| 494 | { |
| 495 | if (addr >= (unsigned long)__kprobes_text_start && |
| 496 | addr < (unsigned long)__kprobes_text_end) |
| 497 | return -EINVAL; |
| 498 | return 0; |
| 499 | } |
| 500 | |
| 501 | /* |
| 502 | * If we have a symbol_name argument, look it up and add the offset field |
| 503 | * to it. This way, we can specify a relative address to a symbol. |
| 504 | */ |
| 505 | static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p) |
| 506 | { |
| 507 | kprobe_opcode_t *addr = p->addr; |
| 508 | if (p->symbol_name) { |
| 509 | if (addr) |
| 510 | return NULL; |
| 511 | kprobe_lookup_name(p->symbol_name, addr); |
| 512 | } |
| 513 | |
| 514 | if (!addr) |
| 515 | return NULL; |
| 516 | return (kprobe_opcode_t *)(((char *)addr) + p->offset); |
| 517 | } |
| 518 | |
| 519 | static int __kprobes __register_kprobe(struct kprobe *p, |
| 520 | unsigned long called_from) |
| 521 | { |
| 522 | int ret = 0; |
| 523 | struct kprobe *old_p; |
| 524 | struct module *probed_mod; |
| 525 | kprobe_opcode_t *addr; |
| 526 | |
| 527 | addr = kprobe_addr(p); |
| 528 | if (!addr) |
| 529 | return -EINVAL; |
| 530 | p->addr = addr; |
| 531 | |
| 532 | if (!kernel_text_address((unsigned long) p->addr) || |
| 533 | in_kprobes_functions((unsigned long) p->addr)) |
| 534 | return -EINVAL; |
| 535 | |
| 536 | p->mod_refcounted = 0; |
| 537 | |
| 538 | /* |
| 539 | * Check if are we probing a module. |
| 540 | */ |
| 541 | probed_mod = module_text_address((unsigned long) p->addr); |
| 542 | if (probed_mod) { |
| 543 | struct module *calling_mod = module_text_address(called_from); |
| 544 | /* |
| 545 | * We must allow modules to probe themself and in this case |
| 546 | * avoid incrementing the module refcount, so as to allow |
| 547 | * unloading of self probing modules. |
| 548 | */ |
| 549 | if (calling_mod && calling_mod != probed_mod) { |
| 550 | if (unlikely(!try_module_get(probed_mod))) |
| 551 | return -EINVAL; |
| 552 | p->mod_refcounted = 1; |
| 553 | } else |
| 554 | probed_mod = NULL; |
| 555 | } |
| 556 | |
| 557 | p->nmissed = 0; |
| 558 | mutex_lock(&kprobe_mutex); |
| 559 | old_p = get_kprobe(p->addr); |
| 560 | if (old_p) { |
| 561 | ret = register_aggr_kprobe(old_p, p); |
| 562 | goto out; |
| 563 | } |
| 564 | |
| 565 | ret = arch_prepare_kprobe(p); |
| 566 | if (ret) |
| 567 | goto out; |
| 568 | |
| 569 | INIT_HLIST_NODE(&p->hlist); |
| 570 | hlist_add_head_rcu(&p->hlist, |
| 571 | &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); |
| 572 | |
| 573 | if (kprobe_enabled) |
| 574 | arch_arm_kprobe(p); |
| 575 | |
| 576 | out: |
| 577 | mutex_unlock(&kprobe_mutex); |
| 578 | |
| 579 | if (ret && probed_mod) |
| 580 | module_put(probed_mod); |
| 581 | return ret; |
| 582 | } |
| 583 | |
| 584 | int __kprobes register_kprobe(struct kprobe *p) |
| 585 | { |
| 586 | return __register_kprobe(p, (unsigned long)__builtin_return_address(0)); |
| 587 | } |
| 588 | |
| 589 | void __kprobes unregister_kprobe(struct kprobe *p) |
| 590 | { |
| 591 | struct module *mod; |
| 592 | struct kprobe *old_p, *list_p; |
| 593 | int cleanup_p; |
| 594 | |
| 595 | mutex_lock(&kprobe_mutex); |
| 596 | old_p = get_kprobe(p->addr); |
| 597 | if (unlikely(!old_p)) { |
| 598 | mutex_unlock(&kprobe_mutex); |
| 599 | return; |
| 600 | } |
| 601 | if (p != old_p) { |
| 602 | list_for_each_entry_rcu(list_p, &old_p->list, list) |
| 603 | if (list_p == p) |
| 604 | /* kprobe p is a valid probe */ |
| 605 | goto valid_p; |
| 606 | mutex_unlock(&kprobe_mutex); |
| 607 | return; |
| 608 | } |
| 609 | valid_p: |
| 610 | if (old_p == p || |
| 611 | (old_p->pre_handler == aggr_pre_handler && |
| 612 | p->list.next == &old_p->list && p->list.prev == &old_p->list)) { |
| 613 | /* |
| 614 | * Only probe on the hash list. Disarm only if kprobes are |
| 615 | * enabled - otherwise, the breakpoint would already have |
| 616 | * been removed. We save on flushing icache. |
| 617 | */ |
| 618 | if (kprobe_enabled) |
| 619 | arch_disarm_kprobe(p); |
| 620 | hlist_del_rcu(&old_p->hlist); |
| 621 | cleanup_p = 1; |
| 622 | } else { |
| 623 | list_del_rcu(&p->list); |
| 624 | cleanup_p = 0; |
| 625 | } |
| 626 | |
| 627 | mutex_unlock(&kprobe_mutex); |
| 628 | |
| 629 | synchronize_sched(); |
| 630 | if (p->mod_refcounted) { |
| 631 | mod = module_text_address((unsigned long)p->addr); |
| 632 | if (mod) |
| 633 | module_put(mod); |
| 634 | } |
| 635 | |
| 636 | if (cleanup_p) { |
| 637 | if (p != old_p) { |
| 638 | list_del_rcu(&p->list); |
| 639 | kfree(old_p); |
| 640 | } |
| 641 | arch_remove_kprobe(p); |
| 642 | } else { |
| 643 | mutex_lock(&kprobe_mutex); |
| 644 | if (p->break_handler) |
| 645 | old_p->break_handler = NULL; |
| 646 | if (p->post_handler){ |
| 647 | list_for_each_entry_rcu(list_p, &old_p->list, list){ |
| 648 | if (list_p->post_handler){ |
| 649 | cleanup_p = 2; |
| 650 | break; |
| 651 | } |
| 652 | } |
| 653 | if (cleanup_p == 0) |
| 654 | old_p->post_handler = NULL; |
| 655 | } |
| 656 | mutex_unlock(&kprobe_mutex); |
| 657 | } |
| 658 | } |
| 659 | |
| 660 | static struct notifier_block kprobe_exceptions_nb = { |
| 661 | .notifier_call = kprobe_exceptions_notify, |
| 662 | .priority = 0x7fffffff /* we need to be notified first */ |
| 663 | }; |
| 664 | |
| 665 | unsigned long __weak arch_deref_entry_point(void *entry) |
| 666 | { |
| 667 | return (unsigned long)entry; |
| 668 | } |
| 669 | |
| 670 | int __kprobes register_jprobe(struct jprobe *jp) |
| 671 | { |
| 672 | unsigned long addr = arch_deref_entry_point(jp->entry); |
| 673 | |
| 674 | if (!kernel_text_address(addr)) |
| 675 | return -EINVAL; |
| 676 | |
| 677 | /* Todo: Verify probepoint is a function entry point */ |
| 678 | jp->kp.pre_handler = setjmp_pre_handler; |
| 679 | jp->kp.break_handler = longjmp_break_handler; |
| 680 | |
| 681 | return __register_kprobe(&jp->kp, |
| 682 | (unsigned long)__builtin_return_address(0)); |
| 683 | } |
| 684 | |
| 685 | void __kprobes unregister_jprobe(struct jprobe *jp) |
| 686 | { |
| 687 | unregister_kprobe(&jp->kp); |
| 688 | } |
| 689 | |
| 690 | #ifdef CONFIG_KRETPROBES |
| 691 | /* |
| 692 | * This kprobe pre_handler is registered with every kretprobe. When probe |
| 693 | * hits it will set up the return probe. |
| 694 | */ |
| 695 | static int __kprobes pre_handler_kretprobe(struct kprobe *p, |
| 696 | struct pt_regs *regs) |
| 697 | { |
| 698 | struct kretprobe *rp = container_of(p, struct kretprobe, kp); |
| 699 | unsigned long flags = 0; |
| 700 | |
| 701 | /*TODO: consider to only swap the RA after the last pre_handler fired */ |
| 702 | spin_lock_irqsave(&kretprobe_lock, flags); |
| 703 | if (!hlist_empty(&rp->free_instances)) { |
| 704 | struct kretprobe_instance *ri; |
| 705 | |
| 706 | ri = hlist_entry(rp->free_instances.first, |
| 707 | struct kretprobe_instance, uflist); |
| 708 | ri->rp = rp; |
| 709 | ri->task = current; |
| 710 | |
| 711 | if (rp->entry_handler && rp->entry_handler(ri, regs)) { |
| 712 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
| 713 | return 0; |
| 714 | } |
| 715 | |
| 716 | arch_prepare_kretprobe(ri, regs); |
| 717 | |
| 718 | /* XXX(hch): why is there no hlist_move_head? */ |
| 719 | hlist_del(&ri->uflist); |
| 720 | hlist_add_head(&ri->uflist, &ri->rp->used_instances); |
| 721 | hlist_add_head(&ri->hlist, kretprobe_inst_table_head(ri->task)); |
| 722 | } else |
| 723 | rp->nmissed++; |
| 724 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
| 725 | return 0; |
| 726 | } |
| 727 | |
| 728 | int __kprobes register_kretprobe(struct kretprobe *rp) |
| 729 | { |
| 730 | int ret = 0; |
| 731 | struct kretprobe_instance *inst; |
| 732 | int i; |
| 733 | void *addr; |
| 734 | |
| 735 | if (kretprobe_blacklist_size) { |
| 736 | addr = kprobe_addr(&rp->kp); |
| 737 | if (!addr) |
| 738 | return -EINVAL; |
| 739 | |
| 740 | for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { |
| 741 | if (kretprobe_blacklist[i].addr == addr) |
| 742 | return -EINVAL; |
| 743 | } |
| 744 | } |
| 745 | |
| 746 | rp->kp.pre_handler = pre_handler_kretprobe; |
| 747 | rp->kp.post_handler = NULL; |
| 748 | rp->kp.fault_handler = NULL; |
| 749 | rp->kp.break_handler = NULL; |
| 750 | |
| 751 | /* Pre-allocate memory for max kretprobe instances */ |
| 752 | if (rp->maxactive <= 0) { |
| 753 | #ifdef CONFIG_PREEMPT |
| 754 | rp->maxactive = max(10, 2 * NR_CPUS); |
| 755 | #else |
| 756 | rp->maxactive = NR_CPUS; |
| 757 | #endif |
| 758 | } |
| 759 | INIT_HLIST_HEAD(&rp->used_instances); |
| 760 | INIT_HLIST_HEAD(&rp->free_instances); |
| 761 | for (i = 0; i < rp->maxactive; i++) { |
| 762 | inst = kmalloc(sizeof(struct kretprobe_instance) + |
| 763 | rp->data_size, GFP_KERNEL); |
| 764 | if (inst == NULL) { |
| 765 | free_rp_inst(rp); |
| 766 | return -ENOMEM; |
| 767 | } |
| 768 | INIT_HLIST_NODE(&inst->uflist); |
| 769 | hlist_add_head(&inst->uflist, &rp->free_instances); |
| 770 | } |
| 771 | |
| 772 | rp->nmissed = 0; |
| 773 | /* Establish function entry probe point */ |
| 774 | if ((ret = __register_kprobe(&rp->kp, |
| 775 | (unsigned long)__builtin_return_address(0))) != 0) |
| 776 | free_rp_inst(rp); |
| 777 | return ret; |
| 778 | } |
| 779 | |
| 780 | #else /* CONFIG_KRETPROBES */ |
| 781 | int __kprobes register_kretprobe(struct kretprobe *rp) |
| 782 | { |
| 783 | return -ENOSYS; |
| 784 | } |
| 785 | |
| 786 | static int __kprobes pre_handler_kretprobe(struct kprobe *p, |
| 787 | struct pt_regs *regs) |
| 788 | { |
| 789 | return 0; |
| 790 | } |
| 791 | #endif /* CONFIG_KRETPROBES */ |
| 792 | |
| 793 | void __kprobes unregister_kretprobe(struct kretprobe *rp) |
| 794 | { |
| 795 | unsigned long flags; |
| 796 | struct kretprobe_instance *ri; |
| 797 | struct hlist_node *pos, *next; |
| 798 | |
| 799 | unregister_kprobe(&rp->kp); |
| 800 | |
| 801 | /* No race here */ |
| 802 | spin_lock_irqsave(&kretprobe_lock, flags); |
| 803 | hlist_for_each_entry_safe(ri, pos, next, &rp->used_instances, uflist) { |
| 804 | ri->rp = NULL; |
| 805 | hlist_del(&ri->uflist); |
| 806 | } |
| 807 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
| 808 | free_rp_inst(rp); |
| 809 | } |
| 810 | |
| 811 | static int __init init_kprobes(void) |
| 812 | { |
| 813 | int i, err = 0; |
| 814 | |
| 815 | /* FIXME allocate the probe table, currently defined statically */ |
| 816 | /* initialize all list heads */ |
| 817 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
| 818 | INIT_HLIST_HEAD(&kprobe_table[i]); |
| 819 | INIT_HLIST_HEAD(&kretprobe_inst_table[i]); |
| 820 | } |
| 821 | |
| 822 | if (kretprobe_blacklist_size) { |
| 823 | /* lookup the function address from its name */ |
| 824 | for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { |
| 825 | kprobe_lookup_name(kretprobe_blacklist[i].name, |
| 826 | kretprobe_blacklist[i].addr); |
| 827 | if (!kretprobe_blacklist[i].addr) |
| 828 | printk("kretprobe: lookup failed: %s\n", |
| 829 | kretprobe_blacklist[i].name); |
| 830 | } |
| 831 | } |
| 832 | |
| 833 | /* By default, kprobes are enabled */ |
| 834 | kprobe_enabled = true; |
| 835 | |
| 836 | err = arch_init_kprobes(); |
| 837 | if (!err) |
| 838 | err = register_die_notifier(&kprobe_exceptions_nb); |
| 839 | |
| 840 | if (!err) |
| 841 | init_test_probes(); |
| 842 | return err; |
| 843 | } |
| 844 | |
| 845 | #ifdef CONFIG_DEBUG_FS |
| 846 | static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p, |
| 847 | const char *sym, int offset,char *modname) |
| 848 | { |
| 849 | char *kprobe_type; |
| 850 | |
| 851 | if (p->pre_handler == pre_handler_kretprobe) |
| 852 | kprobe_type = "r"; |
| 853 | else if (p->pre_handler == setjmp_pre_handler) |
| 854 | kprobe_type = "j"; |
| 855 | else |
| 856 | kprobe_type = "k"; |
| 857 | if (sym) |
| 858 | seq_printf(pi, "%p %s %s+0x%x %s\n", p->addr, kprobe_type, |
| 859 | sym, offset, (modname ? modname : " ")); |
| 860 | else |
| 861 | seq_printf(pi, "%p %s %p\n", p->addr, kprobe_type, p->addr); |
| 862 | } |
| 863 | |
| 864 | static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos) |
| 865 | { |
| 866 | return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL; |
| 867 | } |
| 868 | |
| 869 | static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos) |
| 870 | { |
| 871 | (*pos)++; |
| 872 | if (*pos >= KPROBE_TABLE_SIZE) |
| 873 | return NULL; |
| 874 | return pos; |
| 875 | } |
| 876 | |
| 877 | static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v) |
| 878 | { |
| 879 | /* Nothing to do */ |
| 880 | } |
| 881 | |
| 882 | static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v) |
| 883 | { |
| 884 | struct hlist_head *head; |
| 885 | struct hlist_node *node; |
| 886 | struct kprobe *p, *kp; |
| 887 | const char *sym = NULL; |
| 888 | unsigned int i = *(loff_t *) v; |
| 889 | unsigned long offset = 0; |
| 890 | char *modname, namebuf[128]; |
| 891 | |
| 892 | head = &kprobe_table[i]; |
| 893 | preempt_disable(); |
| 894 | hlist_for_each_entry_rcu(p, node, head, hlist) { |
| 895 | sym = kallsyms_lookup((unsigned long)p->addr, NULL, |
| 896 | &offset, &modname, namebuf); |
| 897 | if (p->pre_handler == aggr_pre_handler) { |
| 898 | list_for_each_entry_rcu(kp, &p->list, list) |
| 899 | report_probe(pi, kp, sym, offset, modname); |
| 900 | } else |
| 901 | report_probe(pi, p, sym, offset, modname); |
| 902 | } |
| 903 | preempt_enable(); |
| 904 | return 0; |
| 905 | } |
| 906 | |
| 907 | static struct seq_operations kprobes_seq_ops = { |
| 908 | .start = kprobe_seq_start, |
| 909 | .next = kprobe_seq_next, |
| 910 | .stop = kprobe_seq_stop, |
| 911 | .show = show_kprobe_addr |
| 912 | }; |
| 913 | |
| 914 | static int __kprobes kprobes_open(struct inode *inode, struct file *filp) |
| 915 | { |
| 916 | return seq_open(filp, &kprobes_seq_ops); |
| 917 | } |
| 918 | |
| 919 | static struct file_operations debugfs_kprobes_operations = { |
| 920 | .open = kprobes_open, |
| 921 | .read = seq_read, |
| 922 | .llseek = seq_lseek, |
| 923 | .release = seq_release, |
| 924 | }; |
| 925 | |
| 926 | static void __kprobes enable_all_kprobes(void) |
| 927 | { |
| 928 | struct hlist_head *head; |
| 929 | struct hlist_node *node; |
| 930 | struct kprobe *p; |
| 931 | unsigned int i; |
| 932 | |
| 933 | mutex_lock(&kprobe_mutex); |
| 934 | |
| 935 | /* If kprobes are already enabled, just return */ |
| 936 | if (kprobe_enabled) |
| 937 | goto already_enabled; |
| 938 | |
| 939 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
| 940 | head = &kprobe_table[i]; |
| 941 | hlist_for_each_entry_rcu(p, node, head, hlist) |
| 942 | arch_arm_kprobe(p); |
| 943 | } |
| 944 | |
| 945 | kprobe_enabled = true; |
| 946 | printk(KERN_INFO "Kprobes globally enabled\n"); |
| 947 | |
| 948 | already_enabled: |
| 949 | mutex_unlock(&kprobe_mutex); |
| 950 | return; |
| 951 | } |
| 952 | |
| 953 | static void __kprobes disable_all_kprobes(void) |
| 954 | { |
| 955 | struct hlist_head *head; |
| 956 | struct hlist_node *node; |
| 957 | struct kprobe *p; |
| 958 | unsigned int i; |
| 959 | |
| 960 | mutex_lock(&kprobe_mutex); |
| 961 | |
| 962 | /* If kprobes are already disabled, just return */ |
| 963 | if (!kprobe_enabled) |
| 964 | goto already_disabled; |
| 965 | |
| 966 | kprobe_enabled = false; |
| 967 | printk(KERN_INFO "Kprobes globally disabled\n"); |
| 968 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
| 969 | head = &kprobe_table[i]; |
| 970 | hlist_for_each_entry_rcu(p, node, head, hlist) { |
| 971 | if (!arch_trampoline_kprobe(p)) |
| 972 | arch_disarm_kprobe(p); |
| 973 | } |
| 974 | } |
| 975 | |
| 976 | mutex_unlock(&kprobe_mutex); |
| 977 | /* Allow all currently running kprobes to complete */ |
| 978 | synchronize_sched(); |
| 979 | return; |
| 980 | |
| 981 | already_disabled: |
| 982 | mutex_unlock(&kprobe_mutex); |
| 983 | return; |
| 984 | } |
| 985 | |
| 986 | /* |
| 987 | * XXX: The debugfs bool file interface doesn't allow for callbacks |
| 988 | * when the bool state is switched. We can reuse that facility when |
| 989 | * available |
| 990 | */ |
| 991 | static ssize_t read_enabled_file_bool(struct file *file, |
| 992 | char __user *user_buf, size_t count, loff_t *ppos) |
| 993 | { |
| 994 | char buf[3]; |
| 995 | |
| 996 | if (kprobe_enabled) |
| 997 | buf[0] = '1'; |
| 998 | else |
| 999 | buf[0] = '0'; |
| 1000 | buf[1] = '\n'; |
| 1001 | buf[2] = 0x00; |
| 1002 | return simple_read_from_buffer(user_buf, count, ppos, buf, 2); |
| 1003 | } |
| 1004 | |
| 1005 | static ssize_t write_enabled_file_bool(struct file *file, |
| 1006 | const char __user *user_buf, size_t count, loff_t *ppos) |
| 1007 | { |
| 1008 | char buf[32]; |
| 1009 | int buf_size; |
| 1010 | |
| 1011 | buf_size = min(count, (sizeof(buf)-1)); |
| 1012 | if (copy_from_user(buf, user_buf, buf_size)) |
| 1013 | return -EFAULT; |
| 1014 | |
| 1015 | switch (buf[0]) { |
| 1016 | case 'y': |
| 1017 | case 'Y': |
| 1018 | case '1': |
| 1019 | enable_all_kprobes(); |
| 1020 | break; |
| 1021 | case 'n': |
| 1022 | case 'N': |
| 1023 | case '0': |
| 1024 | disable_all_kprobes(); |
| 1025 | break; |
| 1026 | } |
| 1027 | |
| 1028 | return count; |
| 1029 | } |
| 1030 | |
| 1031 | static struct file_operations fops_kp = { |
| 1032 | .read = read_enabled_file_bool, |
| 1033 | .write = write_enabled_file_bool, |
| 1034 | }; |
| 1035 | |
| 1036 | static int __kprobes debugfs_kprobe_init(void) |
| 1037 | { |
| 1038 | struct dentry *dir, *file; |
| 1039 | unsigned int value = 1; |
| 1040 | |
| 1041 | dir = debugfs_create_dir("kprobes", NULL); |
| 1042 | if (!dir) |
| 1043 | return -ENOMEM; |
| 1044 | |
| 1045 | file = debugfs_create_file("list", 0444, dir, NULL, |
| 1046 | &debugfs_kprobes_operations); |
| 1047 | if (!file) { |
| 1048 | debugfs_remove(dir); |
| 1049 | return -ENOMEM; |
| 1050 | } |
| 1051 | |
| 1052 | file = debugfs_create_file("enabled", 0600, dir, |
| 1053 | &value, &fops_kp); |
| 1054 | if (!file) { |
| 1055 | debugfs_remove(dir); |
| 1056 | return -ENOMEM; |
| 1057 | } |
| 1058 | |
| 1059 | return 0; |
| 1060 | } |
| 1061 | |
| 1062 | late_initcall(debugfs_kprobe_init); |
| 1063 | #endif /* CONFIG_DEBUG_FS */ |
| 1064 | |
| 1065 | module_init(init_kprobes); |
| 1066 | |
| 1067 | EXPORT_SYMBOL_GPL(register_kprobe); |
| 1068 | EXPORT_SYMBOL_GPL(unregister_kprobe); |
| 1069 | EXPORT_SYMBOL_GPL(register_jprobe); |
| 1070 | EXPORT_SYMBOL_GPL(unregister_jprobe); |
| 1071 | #ifdef CONFIG_KPROBES |
| 1072 | EXPORT_SYMBOL_GPL(jprobe_return); |
| 1073 | #endif |
| 1074 | |
| 1075 | #ifdef CONFIG_KPROBES |
| 1076 | EXPORT_SYMBOL_GPL(register_kretprobe); |
| 1077 | EXPORT_SYMBOL_GPL(unregister_kretprobe); |
| 1078 | #endif |