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 #ifdef CONFIG_KPROBES_SANITY_TEST
 273 extern int init_test_probes(void);
 274 #else /* !CONFIG_KPROBES_SANITY_TEST */
 275 static inline int init_test_probes(void)
 276 {
 277         return 0;
 278 }
 279 #endif /* CONFIG_KPROBES_SANITY_TEST */
 280
 281 extern int arch_prepare_kprobe(struct kprobe *p);
 282 extern void arch_arm_kprobe(struct kprobe *p);
 283 extern void arch_disarm_kprobe(struct kprobe *p);
 284 extern int arch_init_kprobes(void);
 285 extern void kprobes_inc_nmissed_count(struct kprobe *p);
 286 extern bool arch_within_kprobe_blacklist(unsigned long addr);
 287 extern int arch_populate_kprobe_blacklist(void);
 288 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
 289
 290 extern bool within_kprobe_blacklist(unsigned long addr);
 291 extern int kprobe_add_ksym_blacklist(unsigned long entry);
 292 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
 293
 294 struct kprobe_insn_cache {
 295         struct mutex mutex;
 296         void *(*alloc)(void);   /* allocate insn page */
 297         void (*free)(void *);   /* free insn page */
 298         const char *sym;        /* symbol for insn pages */
 299         struct list_head pages; /* list of kprobe_insn_page */
 300         size_t insn_size;       /* size of instruction slot */
 301         int nr_garbage;
 302 };
 303
 304 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 305 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
 306 extern void __free_insn_slot(struct kprobe_insn_cache *c,
 307                              kprobe_opcode_t *slot, int dirty);
 308 /* sleep-less address checking routine  */
 309 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
 310                                 unsigned long addr);
 311
 312 #define DEFINE_INSN_CACHE_OPS(__name)                                   \
 313 extern struct kprobe_insn_cache kprobe_##__name##_slots;                \
 314                                                                         \
 315 static inline kprobe_opcode_t *get_##__name##_slot(void)                \
 316 {                                                                       \
 317         return __get_insn_slot(&kprobe_##__name##_slots);               \
 318 }                                                                       \
 319                                                                         \
 320 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
 321 {                                                                       \
 322         __free_insn_slot(&kprobe_##__name##_slots, slot, dirty);        \
 323 }                                                                       \
 324                                                                         \
 325 static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \
 326 {                                                                       \
 327         return __is_insn_slot_addr(&kprobe_##__name##_slots, addr);     \
 328 }
 329 #define KPROBE_INSN_PAGE_SYM            "kprobe_insn_page"
 330 #define KPROBE_OPTINSN_PAGE_SYM         "kprobe_optinsn_page"
 331 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
 332                              unsigned long *value, char *type, char *sym);
 333 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */
 334 #define DEFINE_INSN_CACHE_OPS(__name)                                   \
 335 static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \
 336 {                                                                       \
 337         return 0;                                                       \
 338 }
 339 #endif
 340
 341 DEFINE_INSN_CACHE_OPS(insn);
 342
 343 #ifdef CONFIG_OPTPROBES
 344 /*
 345  * Internal structure for direct jump optimized probe
 346  */
 347 struct optimized_kprobe {
 348         struct kprobe kp;
 349         struct list_head list;  /* list for optimizing queue */
 350         struct arch_optimized_insn optinsn;
 351 };
 352
 353 /* Architecture dependent functions for direct jump optimization */
 354 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn);
 355 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
 356 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
 357                                          struct kprobe *orig);
 358 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
 359 extern void arch_optimize_kprobes(struct list_head *oplist);
 360 extern void arch_unoptimize_kprobes(struct list_head *oplist,
 361                                     struct list_head *done_list);
 362 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
 363 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
 364                                         kprobe_opcode_t *addr);
 365
 366 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
 367
 368 DEFINE_INSN_CACHE_OPS(optinsn);
 369
 370 extern void wait_for_kprobe_optimizer(void);
 371 bool optprobe_queued_unopt(struct optimized_kprobe *op);
 372 bool kprobe_disarmed(struct kprobe *p);
 373 #else /* !CONFIG_OPTPROBES */
 374 static inline void wait_for_kprobe_optimizer(void) { }
 375 #endif /* CONFIG_OPTPROBES */
 376
 377 #ifdef CONFIG_KPROBES_ON_FTRACE
 378 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 379                                   struct ftrace_ops *ops, struct ftrace_regs *fregs);
 380 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
 381 #else
 382 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
 383 {
 384         return -EINVAL;
 385 }
 386 #endif /* CONFIG_KPROBES_ON_FTRACE */
 387
 388 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 389 struct kprobe *get_kprobe(void *addr);
 390
 391 /* kprobe_running() will just return the current_kprobe on this CPU */
 392 static inline struct kprobe *kprobe_running(void)
 393 {
 394         return __this_cpu_read(current_kprobe);
 395 }
 396
 397 static inline void reset_current_kprobe(void)
 398 {
 399         __this_cpu_write(current_kprobe, NULL);
 400 }
 401
 402 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 403 {
 404         return this_cpu_ptr(&kprobe_ctlblk);
 405 }
 406
 407 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
 408 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry);
 409
 410 int register_kprobe(struct kprobe *p);
 411 void unregister_kprobe(struct kprobe *p);
 412 int register_kprobes(struct kprobe **kps, int num);
 413 void unregister_kprobes(struct kprobe **kps, int num);
 414
 415 int register_kretprobe(struct kretprobe *rp);
 416 void unregister_kretprobe(struct kretprobe *rp);
 417 int register_kretprobes(struct kretprobe **rps, int num);
 418 void unregister_kretprobes(struct kretprobe **rps, int num);
 419
 420 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)
 421 #define kprobe_flush_task(tk)   do {} while (0)
 422 #else
 423 void kprobe_flush_task(struct task_struct *tk);
 424 #endif
 425
 426 void kprobe_free_init_mem(void);
 427
 428 int disable_kprobe(struct kprobe *kp);
 429 int enable_kprobe(struct kprobe *kp);
 430
 431 void dump_kprobe(struct kprobe *kp);
 432
 433 void *alloc_insn_page(void);
 434
 435 void *alloc_optinsn_page(void);
 436 void free_optinsn_page(void *page);
 437
 438 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 439                        char *sym);
 440
 441 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
 442                             char *type, char *sym);
 443
 444 int kprobe_exceptions_notify(struct notifier_block *self,
 445                              unsigned long val, void *data);
 446
 447 #else /* !CONFIG_KPROBES: */
 448
 449 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 450 {
 451         return 0;
 452 }
 453 static inline struct kprobe *get_kprobe(void *addr)
 454 {
 455         return NULL;
 456 }
 457 static inline struct kprobe *kprobe_running(void)
 458 {
 459         return NULL;
 460 }
 461 #define kprobe_busy_begin()     do {} while (0)
 462 #define kprobe_busy_end()       do {} while (0)
 463
 464 static inline int register_kprobe(struct kprobe *p)
 465 {
 466         return -EOPNOTSUPP;
 467 }
 468 static inline int register_kprobes(struct kprobe **kps, int num)
 469 {
 470         return -EOPNOTSUPP;
 471 }
 472 static inline void unregister_kprobe(struct kprobe *p)
 473 {
 474 }
 475 static inline void unregister_kprobes(struct kprobe **kps, int num)
 476 {
 477 }
 478 static inline int register_kretprobe(struct kretprobe *rp)
 479 {
 480         return -EOPNOTSUPP;
 481 }
 482 static inline int register_kretprobes(struct kretprobe **rps, int num)
 483 {
 484         return -EOPNOTSUPP;
 485 }
 486 static inline void unregister_kretprobe(struct kretprobe *rp)
 487 {
 488 }
 489 static inline void unregister_kretprobes(struct kretprobe **rps, int num)
 490 {
 491 }
 492 static inline void kprobe_flush_task(struct task_struct *tk)
 493 {
 494 }
 495 static inline void kprobe_free_init_mem(void)
 496 {
 497 }
 498 static inline int disable_kprobe(struct kprobe *kp)
 499 {
 500         return -EOPNOTSUPP;
 501 }
 502 static inline int enable_kprobe(struct kprobe *kp)
 503 {
 504         return -EOPNOTSUPP;
 505 }
 506
 507 static inline bool within_kprobe_blacklist(unsigned long addr)
 508 {
 509         return true;
 510 }
 511 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
 512                                      char *type, char *sym)
 513 {
 514         return -ERANGE;
 515 }
 516 #endif /* CONFIG_KPROBES */
 517
 518 static inline int disable_kretprobe(struct kretprobe *rp)
 519 {
 520         return disable_kprobe(&rp->kp);
 521 }
 522 static inline int enable_kretprobe(struct kretprobe *rp)
 523 {
 524         return enable_kprobe(&rp->kp);
 525 }
 526
 527 #ifndef CONFIG_KPROBES
 528 static inline bool is_kprobe_insn_slot(unsigned long addr)
 529 {
 530         return false;
 531 }
 532 #endif /* !CONFIG_KPROBES */
 533
 534 #ifndef CONFIG_OPTPROBES
 535 static inline bool is_kprobe_optinsn_slot(unsigned long addr)
 536 {
 537         return false;
 538 }
 539 #endif /* !CONFIG_OPTPROBES */
 540
 541 #ifdef CONFIG_KRETPROBES
 542 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
 543 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
 544 {
 545         return is_rethook_trampoline(addr);
 546 }
 547
 548 static nokprobe_inline
 549 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
 550                                       struct llist_node **cur)
 551 {
 552         return rethook_find_ret_addr(tsk, (unsigned long)fp, cur);
 553 }
 554 #else
 555 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
 556 {
 557         return (void *)addr == kretprobe_trampoline_addr();
 558 }
 559
 560 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
 561                                       struct llist_node **cur);
 562 #endif
 563 #else
 564 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
 565 {
 566         return false;
 567 }
 568
 569 static nokprobe_inline
 570 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
 571                                       struct llist_node **cur)
 572 {
 573         return 0;
 574 }
 575 #endif
 576
 577 /* Returns true if kprobes handled the fault */
 578 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
 579                                               unsigned int trap)
 580 {
 581         if (!IS_ENABLED(CONFIG_KPROBES))
 582                 return false;
 583         if (user_mode(regs))
 584                 return false;
 585         /*
 586          * To be potentially processing a kprobe fault and to be allowed
 587          * to call kprobe_running(), we have to be non-preemptible.
 588          */
 589         if (preemptible())
 590                 return false;
 591         if (!kprobe_running())
 592                 return false;
 593         return kprobe_fault_handler(regs, trap);
 594 }
 595
 596 #endif /* _LINUX_KPROBES_H */