xref: /linux/include/linux/kprobes.h (revision f4db95b68ae68ebaf91d35cc0487ac1cbd04261e)
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 */
595