xref: /linux/include/linux/kprobes.h (revision b17ef04bf3a4346d66404454d6a646343ddc9749)
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	*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 	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
201 		"Kretprobe is accessed from instance under preemptive context");
202 
203 	return (struct kretprobe *)READ_ONCE(ri->node.rethook->data);
204 }
205 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
206 {
207 	return ri->node.ret_addr;
208 }
209 #else
210 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
211 				   struct pt_regs *regs);
212 void arch_kretprobe_fixup_return(struct pt_regs *regs,
213 				 kprobe_opcode_t *correct_ret_addr);
214 
215 void __kretprobe_trampoline(void);
216 /*
217  * Since some architecture uses structured function pointer,
218  * use dereference_function_descriptor() to get real function address.
219  */
220 static nokprobe_inline void *kretprobe_trampoline_addr(void)
221 {
222 	return dereference_kernel_function_descriptor(__kretprobe_trampoline);
223 }
224 
225 /* If the trampoline handler called from a kprobe, use this version */
226 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
227 					     void *frame_pointer);
228 
229 static nokprobe_inline
230 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs,
231 					   void *frame_pointer)
232 {
233 	unsigned long ret;
234 	/*
235 	 * Set a dummy kprobe for avoiding kretprobe recursion.
236 	 * Since kretprobe never runs in kprobe handler, no kprobe must
237 	 * be running at this point.
238 	 */
239 	kprobe_busy_begin();
240 	ret = __kretprobe_trampoline_handler(regs, frame_pointer);
241 	kprobe_busy_end();
242 
243 	return ret;
244 }
245 
246 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
247 {
248 	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
249 		"Kretprobe is accessed from instance under preemptive context");
250 
251 	return READ_ONCE(ri->rph->rp);
252 }
253 
254 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
255 {
256 	return (unsigned long)ri->ret_addr;
257 }
258 #endif /* CONFIG_KRETPROBE_ON_RETHOOK */
259 
260 #else /* !CONFIG_KRETPROBES */
261 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
262 					struct pt_regs *regs)
263 {
264 }
265 static inline int arch_trampoline_kprobe(struct kprobe *p)
266 {
267 	return 0;
268 }
269 #endif /* CONFIG_KRETPROBES */
270 
271 /* Markers of '_kprobe_blacklist' section */
272 extern unsigned long __start_kprobe_blacklist[];
273 extern unsigned long __stop_kprobe_blacklist[];
274 
275 extern struct kretprobe_blackpoint kretprobe_blacklist[];
276 
277 #ifdef CONFIG_KPROBES_SANITY_TEST
278 extern int init_test_probes(void);
279 #else /* !CONFIG_KPROBES_SANITY_TEST */
280 static inline int init_test_probes(void)
281 {
282 	return 0;
283 }
284 #endif /* CONFIG_KPROBES_SANITY_TEST */
285 
286 extern int arch_prepare_kprobe(struct kprobe *p);
287 extern void arch_arm_kprobe(struct kprobe *p);
288 extern void arch_disarm_kprobe(struct kprobe *p);
289 extern int arch_init_kprobes(void);
290 extern void kprobes_inc_nmissed_count(struct kprobe *p);
291 extern bool arch_within_kprobe_blacklist(unsigned long addr);
292 extern int arch_populate_kprobe_blacklist(void);
293 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
294 
295 extern bool within_kprobe_blacklist(unsigned long addr);
296 extern int kprobe_add_ksym_blacklist(unsigned long entry);
297 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
298 
299 struct kprobe_insn_cache {
300 	struct mutex mutex;
301 	void *(*alloc)(void);	/* allocate insn page */
302 	void (*free)(void *);	/* free insn page */
303 	const char *sym;	/* symbol for insn pages */
304 	struct list_head pages; /* list of kprobe_insn_page */
305 	size_t insn_size;	/* size of instruction slot */
306 	int nr_garbage;
307 };
308 
309 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
310 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
311 extern void __free_insn_slot(struct kprobe_insn_cache *c,
312 			     kprobe_opcode_t *slot, int dirty);
313 /* sleep-less address checking routine  */
314 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
315 				unsigned long addr);
316 
317 #define DEFINE_INSN_CACHE_OPS(__name)					\
318 extern struct kprobe_insn_cache kprobe_##__name##_slots;		\
319 									\
320 static inline kprobe_opcode_t *get_##__name##_slot(void)		\
321 {									\
322 	return __get_insn_slot(&kprobe_##__name##_slots);		\
323 }									\
324 									\
325 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
326 {									\
327 	__free_insn_slot(&kprobe_##__name##_slots, slot, dirty);	\
328 }									\
329 									\
330 static inline bool is_kprobe_##__name##_slot(unsigned long addr)	\
331 {									\
332 	return __is_insn_slot_addr(&kprobe_##__name##_slots, addr);	\
333 }
334 #define KPROBE_INSN_PAGE_SYM		"kprobe_insn_page"
335 #define KPROBE_OPTINSN_PAGE_SYM		"kprobe_optinsn_page"
336 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
337 			     unsigned long *value, char *type, char *sym);
338 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */
339 #define DEFINE_INSN_CACHE_OPS(__name)					\
340 static inline bool is_kprobe_##__name##_slot(unsigned long addr)	\
341 {									\
342 	return 0;							\
343 }
344 #endif
345 
346 DEFINE_INSN_CACHE_OPS(insn);
347 
348 #ifdef CONFIG_OPTPROBES
349 /*
350  * Internal structure for direct jump optimized probe
351  */
352 struct optimized_kprobe {
353 	struct kprobe kp;
354 	struct list_head list;	/* list for optimizing queue */
355 	struct arch_optimized_insn optinsn;
356 };
357 
358 /* Architecture dependent functions for direct jump optimization */
359 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn);
360 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
361 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
362 					 struct kprobe *orig);
363 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
364 extern void arch_optimize_kprobes(struct list_head *oplist);
365 extern void arch_unoptimize_kprobes(struct list_head *oplist,
366 				    struct list_head *done_list);
367 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
368 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
369 					kprobe_opcode_t *addr);
370 
371 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
372 
373 DEFINE_INSN_CACHE_OPS(optinsn);
374 
375 extern void wait_for_kprobe_optimizer(void);
376 bool optprobe_queued_unopt(struct optimized_kprobe *op);
377 bool kprobe_disarmed(struct kprobe *p);
378 #else /* !CONFIG_OPTPROBES */
379 static inline void wait_for_kprobe_optimizer(void) { }
380 #endif /* CONFIG_OPTPROBES */
381 
382 #ifdef CONFIG_KPROBES_ON_FTRACE
383 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
384 				  struct ftrace_ops *ops, struct ftrace_regs *fregs);
385 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
386 #else
387 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
388 {
389 	return -EINVAL;
390 }
391 #endif /* CONFIG_KPROBES_ON_FTRACE */
392 
393 /* Get the kprobe at this addr (if any) - called with preemption disabled */
394 struct kprobe *get_kprobe(void *addr);
395 
396 /* kprobe_running() will just return the current_kprobe on this CPU */
397 static inline struct kprobe *kprobe_running(void)
398 {
399 	return __this_cpu_read(current_kprobe);
400 }
401 
402 static inline void reset_current_kprobe(void)
403 {
404 	__this_cpu_write(current_kprobe, NULL);
405 }
406 
407 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
408 {
409 	return this_cpu_ptr(&kprobe_ctlblk);
410 }
411 
412 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
413 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry);
414 
415 int register_kprobe(struct kprobe *p);
416 void unregister_kprobe(struct kprobe *p);
417 int register_kprobes(struct kprobe **kps, int num);
418 void unregister_kprobes(struct kprobe **kps, int num);
419 
420 int register_kretprobe(struct kretprobe *rp);
421 void unregister_kretprobe(struct kretprobe *rp);
422 int register_kretprobes(struct kretprobe **rps, int num);
423 void unregister_kretprobes(struct kretprobe **rps, int num);
424 
425 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)
426 #define kprobe_flush_task(tk)	do {} while (0)
427 #else
428 void kprobe_flush_task(struct task_struct *tk);
429 #endif
430 
431 void kprobe_free_init_mem(void);
432 
433 int disable_kprobe(struct kprobe *kp);
434 int enable_kprobe(struct kprobe *kp);
435 
436 void dump_kprobe(struct kprobe *kp);
437 
438 void *alloc_insn_page(void);
439 
440 void *alloc_optinsn_page(void);
441 void free_optinsn_page(void *page);
442 
443 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
444 		       char *sym);
445 
446 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
447 			    char *type, char *sym);
448 
449 int kprobe_exceptions_notify(struct notifier_block *self,
450 			     unsigned long val, void *data);
451 
452 #else /* !CONFIG_KPROBES: */
453 
454 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
455 {
456 	return 0;
457 }
458 static inline struct kprobe *get_kprobe(void *addr)
459 {
460 	return NULL;
461 }
462 static inline struct kprobe *kprobe_running(void)
463 {
464 	return NULL;
465 }
466 #define kprobe_busy_begin()	do {} while (0)
467 #define kprobe_busy_end()	do {} while (0)
468 
469 static inline int register_kprobe(struct kprobe *p)
470 {
471 	return -EOPNOTSUPP;
472 }
473 static inline int register_kprobes(struct kprobe **kps, int num)
474 {
475 	return -EOPNOTSUPP;
476 }
477 static inline void unregister_kprobe(struct kprobe *p)
478 {
479 }
480 static inline void unregister_kprobes(struct kprobe **kps, int num)
481 {
482 }
483 static inline int register_kretprobe(struct kretprobe *rp)
484 {
485 	return -EOPNOTSUPP;
486 }
487 static inline int register_kretprobes(struct kretprobe **rps, int num)
488 {
489 	return -EOPNOTSUPP;
490 }
491 static inline void unregister_kretprobe(struct kretprobe *rp)
492 {
493 }
494 static inline void unregister_kretprobes(struct kretprobe **rps, int num)
495 {
496 }
497 static inline void kprobe_flush_task(struct task_struct *tk)
498 {
499 }
500 static inline void kprobe_free_init_mem(void)
501 {
502 }
503 static inline int disable_kprobe(struct kprobe *kp)
504 {
505 	return -EOPNOTSUPP;
506 }
507 static inline int enable_kprobe(struct kprobe *kp)
508 {
509 	return -EOPNOTSUPP;
510 }
511 
512 static inline bool within_kprobe_blacklist(unsigned long addr)
513 {
514 	return true;
515 }
516 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
517 				     char *type, char *sym)
518 {
519 	return -ERANGE;
520 }
521 #endif /* CONFIG_KPROBES */
522 
523 static inline int disable_kretprobe(struct kretprobe *rp)
524 {
525 	return disable_kprobe(&rp->kp);
526 }
527 static inline int enable_kretprobe(struct kretprobe *rp)
528 {
529 	return enable_kprobe(&rp->kp);
530 }
531 
532 #ifndef CONFIG_KPROBES
533 static inline bool is_kprobe_insn_slot(unsigned long addr)
534 {
535 	return false;
536 }
537 #endif /* !CONFIG_KPROBES */
538 
539 #ifndef CONFIG_OPTPROBES
540 static inline bool is_kprobe_optinsn_slot(unsigned long addr)
541 {
542 	return false;
543 }
544 #endif /* !CONFIG_OPTPROBES */
545 
546 #ifdef CONFIG_KRETPROBES
547 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
548 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
549 {
550 	return is_rethook_trampoline(addr);
551 }
552 
553 static nokprobe_inline
554 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
555 				      struct llist_node **cur)
556 {
557 	return rethook_find_ret_addr(tsk, (unsigned long)fp, cur);
558 }
559 #else
560 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
561 {
562 	return (void *)addr == kretprobe_trampoline_addr();
563 }
564 
565 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
566 				      struct llist_node **cur);
567 #endif
568 #else
569 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
570 {
571 	return false;
572 }
573 
574 static nokprobe_inline
575 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
576 				      struct llist_node **cur)
577 {
578 	return 0;
579 }
580 #endif
581 
582 /* Returns true if kprobes handled the fault */
583 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
584 					      unsigned int trap)
585 {
586 	if (!IS_ENABLED(CONFIG_KPROBES))
587 		return false;
588 	if (user_mode(regs))
589 		return false;
590 	/*
591 	 * To be potentially processing a kprobe fault and to be allowed
592 	 * to call kprobe_running(), we have to be non-preemptible.
593 	 */
594 	if (preemptible())
595 		return false;
596 	if (!kprobe_running())
597 		return false;
598 	return kprobe_fault_handler(regs, trap);
599 }
600 
601 #endif /* _LINUX_KPROBES_H */
602