include/linux/kprobes.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 #ifndef _LINUX_KPROBES_H
   3 #define _LINUX_KPROBES_H
   4 /*
   5  *  Kernel Probes (KProbes)
   6  *
   7  * Copyright (C) IBM Corporation, 2002, 2004
   8  *
   9  * 2002-Oct     Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
  10  *              Probes initial implementation ( includes suggestions from
  11  *              Rusty Russell).
  12  * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
  13  *              interface to access function arguments.
  14  * 2005-May     Hien Nguyen <hien@us.ibm.com> and Jim Keniston
  15  *              <jkenisto@us.ibm.com>  and Prasanna S Panchamukhi
  16  *              <prasanna@in.ibm.com> added function-return probes.
  17  */
  18 #include <linux/compiler.h>
  19 #include <linux/linkage.h>
  20 #include <linux/list.h>
  21 #include <linux/notifier.h>
  22 #include <linux/smp.h>
  23 #include <linux/bug.h>
  24 #include <linux/percpu.h>
  25 #include <linux/spinlock.h>
  26 #include <linux/rcupdate.h>
  27 #include <linux/mutex.h>
  28 #include <linux/ftrace.h>
  29 #include <linux/objpool.h>
  30 #include <linux/rethook.h>
  31 #include <asm/kprobes.h>
  32
  33 #ifdef CONFIG_KPROBES
  34
  35 /* kprobe_status settings */
  36 #define KPROBE_HIT_ACTIVE       0x00000001
  37 #define KPROBE_HIT_SS           0x00000002
  38 #define KPROBE_REENTER          0x00000004
  39 #define KPROBE_HIT_SSDONE       0x00000008
  40
  41 #else /* !CONFIG_KPROBES */
  42 #include <asm-generic/kprobes.h>
  43 typedef int kprobe_opcode_t;
  44 struct arch_specific_insn {
  45         int dummy;
  46 };
  47 #endif /* CONFIG_KPROBES */
  48
  49 struct kprobe;
  50 struct pt_regs;
  51 struct kretprobe;
  52 struct kretprobe_instance;
  53 typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *);
  54 typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *,
  55                                        unsigned long flags);
  56 typedef int (*kretprobe_handler_t) (struct kretprobe_instance *,
  57                                     struct pt_regs *);
  58
  59 struct kprobe {
  60         struct hlist_node hlist;
  61
  62         /* list of kprobes for multi-handler support */
  63         struct list_head list;
  64
  65         /*count the number of times this probe was temporarily disarmed */
  66         unsigned long nmissed;
  67
  68         /* location of the probe point */
  69         kprobe_opcode_t *addr;
  70
  71         /* Allow user to indicate symbol name of the probe point */
  72         const char *symbol_name;
  73
  74         /* Offset into the symbol */
  75         unsigned int offset;
  76
  77         /* Called before addr is executed. */
  78         kprobe_pre_handler_t pre_handler;
  79
  80         /* Called after addr is executed, unless... */
  81         kprobe_post_handler_t post_handler;
  82
  83         /* Saved opcode (which has been replaced with breakpoint) */
  84         kprobe_opcode_t opcode;
  85
  86         /* copy of the original instruction */
  87         struct arch_specific_insn ainsn;
  88
  89         /*
  90          * Indicates various status flags.
  91          * Protected by kprobe_mutex after this kprobe is registered.
  92          */
  93         u32 flags;
  94 };
  95
  96 /* Kprobe status flags */
  97 #define KPROBE_FLAG_GONE        1 /* breakpoint has already gone */
  98 #define KPROBE_FLAG_DISABLED    2 /* probe is temporarily disabled */
  99 #define KPROBE_FLAG_OPTIMIZED   4 /*
 100                                    * probe is really optimized.
 101                                    * NOTE:
 102                                    * this flag is only for optimized_kprobe.
 103                                    */
 104 #define KPROBE_FLAG_FTRACE      8 /* probe is using ftrace */
 105 #define KPROBE_FLAG_ON_FUNC_ENTRY       16 /* probe is on the function entry */
 106
 107 /* Has this kprobe gone ? */
 108 static inline bool kprobe_gone(struct kprobe *p)
 109 {
 110         return p->flags & KPROBE_FLAG_GONE;
 111 }
 112
 113 /* Is this kprobe disabled ? */
 114 static inline bool kprobe_disabled(struct kprobe *p)
 115 {
 116         return p->flags & (KPROBE_FLAG_DISABLED | KPROBE_FLAG_GONE);
 117 }
 118
 119 /* Is this kprobe really running optimized path ? */
 120 static inline bool kprobe_optimized(struct kprobe *p)
 121 {
 122         return p->flags & KPROBE_FLAG_OPTIMIZED;
 123 }
 124
 125 /* Is this kprobe uses ftrace ? */
 126 static inline bool kprobe_ftrace(struct kprobe *p)
 127 {
 128         return p->flags & KPROBE_FLAG_FTRACE;
 129 }
 130
 131 /*
 132  * Function-return probe -
 133  * Note:
 134  * User needs to provide a handler function, and initialize maxactive.
 135  * maxactive - The maximum number of instances of the probed function that
 136  * can be active concurrently.
 137  * nmissed - tracks the number of times the probed function's return was
 138  * ignored, due to maxactive being too low.
 139  *
 140  */
 141 struct kretprobe_holder {
 142         struct kretprobe __rcu *rp;
 143         struct objpool_head     pool;
 144 };
 145
 146 struct kretprobe {
 147         struct kprobe kp;
 148         kretprobe_handler_t handler;
 149         kretprobe_handler_t entry_handler;
 150         int maxactive;
 151         int nmissed;
 152         size_t data_size;
 153 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
 154         struct rethook *rh;
 155 #else
 156         struct kretprobe_holder *rph;
 157 #endif
 158 };
 159
 160 #define KRETPROBE_MAX_DATA_SIZE 4096
 161
 162 struct kretprobe_instance {
 163 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
 164         struct rethook_node node;
 165 #else
 166         struct rcu_head rcu;
 167         struct llist_node llist;
 168         struct kretprobe_holder *rph;
 169         kprobe_opcode_t *ret_addr;
 170         void *fp;
 171 #endif
 172         char data[];
 173 };
 174
 175 struct kretprobe_blackpoint {
 176         const char *name;
 177         void *addr;
 178 };
 179
 180 struct kprobe_blacklist_entry {
 181         struct list_head list;
 182         unsigned long start_addr;
 183         unsigned long end_addr;
 184 };
 185
 186 #ifdef CONFIG_KPROBES
 187 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
 188 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 189
 190 extern void kprobe_busy_begin(void);
 191 extern void kprobe_busy_end(void);
 192
 193 #ifdef CONFIG_KRETPROBES
 194 /* Check whether @p is used for implementing a trampoline. */
 195 extern int arch_trampoline_kprobe(struct kprobe *p);
 196
 197 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
 198 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
 199 {
 200         /* rethook::data is non-changed field, so that you can access it freely. */
 201         return (struct kretprobe *)ri->node.rethook->data;
 202 }
 203 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
 204 {
 205         return ri->node.ret_addr;
 206 }
 207 #else
 208 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
 209                                    struct pt_regs *regs);
 210 void arch_kretprobe_fixup_return(struct pt_regs *regs,
 211                                  kprobe_opcode_t *correct_ret_addr);
 212
 213 void __kretprobe_trampoline(void);
 214 /*
 215  * Since some architecture uses structured function pointer,
 216  * use dereference_function_descriptor() to get real function address.
 217  */
 218 static nokprobe_inline void *kretprobe_trampoline_addr(void)
 219 {
 220         return dereference_kernel_function_descriptor(__kretprobe_trampoline);
 221 }
 222
 223 /* If the trampoline handler called from a kprobe, use this version */
 224 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
 225                                              void *frame_pointer);
 226
 227 static nokprobe_inline
 228 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs,
 229                                            void *frame_pointer)
 230 {
 231         unsigned long ret;
 232         /*
 233          * Set a dummy kprobe for avoiding kretprobe recursion.
 234          * Since kretprobe never runs in kprobe handler, no kprobe must
 235          * be running at this point.
 236          */
 237         kprobe_busy_begin();
 238         ret = __kretprobe_trampoline_handler(regs, frame_pointer);
 239         kprobe_busy_end();
 240
 241         return ret;
 242 }
 243
 244 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
 245 {
 246         return rcu_dereference_check(ri->rph->rp, rcu_read_lock_any_held());
 247 }
 248
 249 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
 250 {
 251         return (unsigned long)ri->ret_addr;
 252 }
 253 #endif /* CONFIG_KRETPROBE_ON_RETHOOK */
 254
 255 #else /* !CONFIG_KRETPROBES */
 256 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 257                                         struct pt_regs *regs)
 258 {
 259 }
 260 static inline int arch_trampoline_kprobe(struct kprobe *p)
 261 {
 262         return 0;
 263 }
 264 #endif /* CONFIG_KRETPROBES */
 265
 266 /* Markers of '_kprobe_blacklist' section */
 267 extern unsigned long __start_kprobe_blacklist[];
 268 extern unsigned long __stop_kprobe_blacklist[];
 269
 270 extern struct kretprobe_blackpoint kretprobe_blacklist[];
 271
 272 extern int arch_prepare_kprobe(struct kprobe *p);
 273 extern void arch_arm_kprobe(struct kprobe *p);
 274 extern void arch_disarm_kprobe(struct kprobe *p);
 275 extern int arch_init_kprobes(void);
 276 extern void kprobes_inc_nmissed_count(struct kprobe *p);
 277 extern bool arch_within_kprobe_blacklist(unsigned long addr);
 278 extern int arch_populate_kprobe_blacklist(void);
 279 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
 280
 281 extern bool within_kprobe_blacklist(unsigned long addr);
 282 extern int kprobe_add_ksym_blacklist(unsigned long entry);
 283 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
 284
 285 struct kprobe_insn_cache {
 286         struct mutex mutex;
 287         void *(*alloc)(void);   /* allocate insn page */
 288         void (*free)(void *);   /* free insn page */
 289         const char *sym;        /* symbol for insn pages */
 290         struct list_head pages; /* list of kprobe_insn_page */
 291         size_t insn_size;       /* size of instruction slot */
 292         int nr_garbage;
 293 };
 294
 295 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 296 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
 297 extern void __free_insn_slot(struct kprobe_insn_cache *c,
 298                              kprobe_opcode_t *slot, int dirty);
 299 /* sleep-less address checking routine  */
 300 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
 301                                 unsigned long addr);
 302
 303 #define DEFINE_INSN_CACHE_OPS(__name)                                   \
 304 extern struct kprobe_insn_cache kprobe_##__name##_slots;                \
 305                                                                         \
 306 static inline kprobe_opcode_t *get_##__name##_slot(void)                \
 307 {                                                                       \
 308         return __get_insn_slot(&kprobe_##__name##_slots);               \
 309 }                                                                       \
 310                                                                         \
 311 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
 312 {                                                                       \
 313         __free_insn_slot(&kprobe_##__name##_slots, slot, dirty);        \
 314 }                                                                       \
 315                                                                         \
 316 static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \
 317 {                                                                       \
 318         return __is_insn_slot_addr(&kprobe_##__name##_slots, addr);     \
 319 }
 320 #define KPROBE_INSN_PAGE_SYM            "kprobe_insn_page"
 321 #define KPROBE_OPTINSN_PAGE_SYM         "kprobe_optinsn_page"
 322 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
 323                              unsigned long *value, char *type, char *sym);
 324 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */
 325 #define DEFINE_INSN_CACHE_OPS(__name)                                   \
 326 static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \
 327 {                                                                       \
 328         return 0;                                                       \
 329 }
 330 #endif
 331
 332 DEFINE_INSN_CACHE_OPS(insn);
 333
 334 #ifdef CONFIG_OPTPROBES
 335 /*
 336  * Internal structure for direct jump optimized probe
 337  */
 338 struct optimized_kprobe {
 339         struct kprobe kp;
 340         struct list_head list;  /* list for optimizing queue */
 341         struct arch_optimized_insn optinsn;
 342 };
 343
 344 /* Architecture dependent functions for direct jump optimization */
 345 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn);
 346 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
 347 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
 348                                          struct kprobe *orig);
 349 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
 350 extern void arch_optimize_kprobes(struct list_head *oplist);
 351 extern void arch_unoptimize_kprobes(struct list_head *oplist,
 352                                     struct list_head *done_list);
 353 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
 354 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
 355                                         kprobe_opcode_t *addr);
 356
 357 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
 358
 359 DEFINE_INSN_CACHE_OPS(optinsn);
 360
 361 extern void wait_for_kprobe_optimizer(void);
 362 bool optprobe_queued_unopt(struct optimized_kprobe *op);
 363 bool kprobe_disarmed(struct kprobe *p);
 364 #else /* !CONFIG_OPTPROBES */
 365 static inline void wait_for_kprobe_optimizer(void) { }
 366 #endif /* CONFIG_OPTPROBES */
 367
 368 #ifdef CONFIG_KPROBES_ON_FTRACE
 369 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 370                                   struct ftrace_ops *ops, struct ftrace_regs *fregs);
 371 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
 372 /* Set when ftrace has been killed: kprobes on ftrace must be disabled for safety */
 373 extern bool kprobe_ftrace_disabled __read_mostly;
 374 extern void kprobe_ftrace_kill(void);
 375 #else
 376 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
 377 {
 378         return -EINVAL;
 379 }
 380 static inline void kprobe_ftrace_kill(void) {}
 381 #endif /* CONFIG_KPROBES_ON_FTRACE */
 382
 383 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 384 struct kprobe *get_kprobe(void *addr);
 385
 386 /* kprobe_running() will just return the current_kprobe on this CPU */
 387 static inline struct kprobe *kprobe_running(void)
 388 {
 389         return __this_cpu_read(current_kprobe);
 390 }
 391
 392 static inline void reset_current_kprobe(void)
 393 {
 394         __this_cpu_write(current_kprobe, NULL);
 395 }
 396
 397 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 398 {
 399         return this_cpu_ptr(&kprobe_ctlblk);
 400 }
 401
 402 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
 403 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry);
 404
 405 int register_kprobe(struct kprobe *p);
 406 void unregister_kprobe(struct kprobe *p);
 407 int register_kprobes(struct kprobe **kps, int num);
 408 void unregister_kprobes(struct kprobe **kps, int num);
 409
 410 int register_kretprobe(struct kretprobe *rp);
 411 void unregister_kretprobe(struct kretprobe *rp);
 412 int register_kretprobes(struct kretprobe **rps, int num);
 413 void unregister_kretprobes(struct kretprobe **rps, int num);
 414
 415 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)
 416 #define kprobe_flush_task(tk)   do {} while (0)
 417 #else
 418 void kprobe_flush_task(struct task_struct *tk);
 419 #endif
 420
 421 void kprobe_free_init_mem(void);
 422
 423 int disable_kprobe(struct kprobe *kp);
 424 int enable_kprobe(struct kprobe *kp);
 425
 426 void dump_kprobe(struct kprobe *kp);
 427
 428 void *alloc_insn_page(void);
 429
 430 void *alloc_optinsn_page(void);
 431 void free_optinsn_page(void *page);
 432
 433 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 434                        char *sym);
 435
 436 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
 437                             char *type, char *sym);
 438
 439 int kprobe_exceptions_notify(struct notifier_block *self,
 440                              unsigned long val, void *data);
 441
 442 #else /* !CONFIG_KPROBES: */
 443
 444 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 445 {
 446         return 0;
 447 }
 448 static inline struct kprobe *get_kprobe(void *addr)
 449 {
 450         return NULL;
 451 }
 452 static inline struct kprobe *kprobe_running(void)
 453 {
 454         return NULL;
 455 }
 456 #define kprobe_busy_begin()     do {} while (0)
 457 #define kprobe_busy_end()       do {} while (0)
 458
 459 static inline int register_kprobe(struct kprobe *p)
 460 {
 461         return -EOPNOTSUPP;
 462 }
 463 static inline int register_kprobes(struct kprobe **kps, int num)
 464 {
 465         return -EOPNOTSUPP;
 466 }
 467 static inline void unregister_kprobe(struct kprobe *p)
 468 {
 469 }
 470 static inline void unregister_kprobes(struct kprobe **kps, int num)
 471 {
 472 }
 473 static inline int register_kretprobe(struct kretprobe *rp)
 474 {
 475         return -EOPNOTSUPP;
 476 }
 477 static inline int register_kretprobes(struct kretprobe **rps, int num)
 478 {
 479         return -EOPNOTSUPP;
 480 }
 481 static inline void unregister_kretprobe(struct kretprobe *rp)
 482 {
 483 }
 484 static inline void unregister_kretprobes(struct kretprobe **rps, int num)
 485 {
 486 }
 487 static inline void kprobe_flush_task(struct task_struct *tk)
 488 {
 489 }
 490 static inline void kprobe_free_init_mem(void)
 491 {
 492 }
 493 static inline void kprobe_ftrace_kill(void)
 494 {
 495 }
 496 static inline int disable_kprobe(struct kprobe *kp)
 497 {
 498         return -EOPNOTSUPP;
 499 }
 500 static inline int enable_kprobe(struct kprobe *kp)
 501 {
 502         return -EOPNOTSUPP;
 503 }
 504
 505 static inline bool within_kprobe_blacklist(unsigned long addr)
 506 {
 507         return true;
 508 }
 509 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
 510                                      char *type, char *sym)
 511 {
 512         return -ERANGE;
 513 }
 514 #endif /* CONFIG_KPROBES */
 515
 516 static inline int disable_kretprobe(struct kretprobe *rp)
 517 {
 518         return disable_kprobe(&rp->kp);
 519 }
 520 static inline int enable_kretprobe(struct kretprobe *rp)
 521 {
 522         return enable_kprobe(&rp->kp);
 523 }
 524
 525 #ifndef CONFIG_KPROBES
 526 static inline bool is_kprobe_insn_slot(unsigned long addr)
 527 {
 528         return false;
 529 }
 530 #endif /* !CONFIG_KPROBES */
 531
 532 #ifndef CONFIG_OPTPROBES
 533 static inline bool is_kprobe_optinsn_slot(unsigned long addr)
 534 {
 535         return false;
 536 }
 537 #endif /* !CONFIG_OPTPROBES */
 538
 539 #ifdef CONFIG_KRETPROBES
 540 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
 541 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
 542 {
 543         return is_rethook_trampoline(addr);
 544 }
 545
 546 static nokprobe_inline
 547 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
 548                                       struct llist_node **cur)
 549 {
 550         return rethook_find_ret_addr(tsk, (unsigned long)fp, cur);
 551 }
 552 #else
 553 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
 554 {
 555         return (void *)addr == kretprobe_trampoline_addr();
 556 }
 557
 558 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
 559                                       struct llist_node **cur);
 560 #endif
 561 #else
 562 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
 563 {
 564         return false;
 565 }
 566
 567 static nokprobe_inline
 568 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
 569                                       struct llist_node **cur)
 570 {
 571         return 0;
 572 }
 573 #endif
 574
 575 /* Returns true if kprobes handled the fault */
 576 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
 577                                               unsigned int trap)
 578 {
 579         if (!IS_ENABLED(CONFIG_KPROBES))
 580                 return false;
 581         if (user_mode(regs))
 582                 return false;
 583         /*
 584          * To be potentially processing a kprobe fault and to be allowed
 585          * to call kprobe_running(), we have to be non-preemptible.
 586          */
 587         if (preemptible())
 588                 return false;
 589         if (!kprobe_running())
 590                 return false;
 591         return kprobe_fault_handler(regs, trap);
 592 }
 593
 594 #endif /* _LINUX_KPROBES_H */