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 ? */
kprobe_gone(struct kprobe * p)108 static inline bool kprobe_gone(struct kprobe *p)
109 {
110 return p->flags & KPROBE_FLAG_GONE;
111 }
112
113 /* Is this kprobe disabled ? */
kprobe_disabled(struct kprobe * p)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 ? */
kprobe_optimized(struct kprobe * p)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 ? */
kprobe_ftrace(struct kprobe * p)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 struct rcu_head rcu;
185 };
186
187 #ifdef CONFIG_KPROBES
188 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
189 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
190
191 extern void kprobe_busy_begin(void);
192 extern void kprobe_busy_end(void);
193
194 #ifdef CONFIG_KRETPROBES
195 /* Check whether @p is used for implementing a trampoline. */
196 extern int arch_trampoline_kprobe(struct kprobe *p);
197
198 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
get_kretprobe(struct kretprobe_instance * ri)199 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
200 {
201 /* rethook::data is non-changed field, so that you can access it freely. */
202 return (struct kretprobe *)ri->node.rethook->data;
203 }
get_kretprobe_retaddr(struct kretprobe_instance * ri)204 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
205 {
206 return ri->node.ret_addr;
207 }
208 #else
209 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
210 struct pt_regs *regs);
211 void arch_kretprobe_fixup_return(struct pt_regs *regs,
212 kprobe_opcode_t *correct_ret_addr);
213
214 void __kretprobe_trampoline(void);
215 /*
216 * Since some architecture uses structured function pointer,
217 * use dereference_function_descriptor() to get real function address.
218 */
kretprobe_trampoline_addr(void)219 static nokprobe_inline void *kretprobe_trampoline_addr(void)
220 {
221 return dereference_kernel_function_descriptor(__kretprobe_trampoline);
222 }
223
224 /* If the trampoline handler called from a kprobe, use this version */
225 unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
226 void *frame_pointer);
227
228 static nokprobe_inline
kretprobe_trampoline_handler(struct pt_regs * regs,void * frame_pointer)229 unsigned long kretprobe_trampoline_handler(struct pt_regs *regs,
230 void *frame_pointer)
231 {
232 unsigned long ret;
233 /*
234 * Set a dummy kprobe for avoiding kretprobe recursion.
235 * Since kretprobe never runs in kprobe handler, no kprobe must
236 * be running at this point.
237 */
238 kprobe_busy_begin();
239 ret = __kretprobe_trampoline_handler(regs, frame_pointer);
240 kprobe_busy_end();
241
242 return ret;
243 }
244
get_kretprobe(struct kretprobe_instance * ri)245 static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
246 {
247 return rcu_dereference_check(ri->rph->rp, rcu_read_lock_any_held());
248 }
249
get_kretprobe_retaddr(struct kretprobe_instance * ri)250 static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
251 {
252 return (unsigned long)ri->ret_addr;
253 }
254 #endif /* CONFIG_KRETPROBE_ON_RETHOOK */
255
256 #else /* !CONFIG_KRETPROBES */
arch_prepare_kretprobe(struct kretprobe * rp,struct pt_regs * regs)257 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
258 struct pt_regs *regs)
259 {
260 }
arch_trampoline_kprobe(struct kprobe * p)261 static inline int arch_trampoline_kprobe(struct kprobe *p)
262 {
263 return 0;
264 }
265 #endif /* CONFIG_KRETPROBES */
266
267 /* Markers of '_kprobe_blacklist' section */
268 extern unsigned long __start_kprobe_blacklist[];
269 extern unsigned long __stop_kprobe_blacklist[];
270
271 extern struct kretprobe_blackpoint kretprobe_blacklist[];
272
273 extern int arch_prepare_kprobe(struct kprobe *p);
274 extern void arch_arm_kprobe(struct kprobe *p);
275 extern void arch_disarm_kprobe(struct kprobe *p);
276 extern int arch_init_kprobes(void);
277 extern void kprobes_inc_nmissed_count(struct kprobe *p);
278 extern bool arch_within_kprobe_blacklist(unsigned long addr);
279 extern int arch_populate_kprobe_blacklist(void);
280 extern int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
281
282 extern bool within_kprobe_blacklist(unsigned long addr);
283 extern int kprobe_add_ksym_blacklist(unsigned long entry);
284 extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
285
286 struct kprobe_insn_cache {
287 struct mutex mutex;
288 void *(*alloc)(void); /* allocate insn page */
289 void (*free)(void *); /* free insn page */
290 const char *sym; /* symbol for insn pages */
291 struct list_head pages; /* list of kprobe_insn_page */
292 size_t insn_size; /* size of instruction slot */
293 int nr_garbage;
294 };
295
296 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
297 extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
298 extern void __free_insn_slot(struct kprobe_insn_cache *c,
299 kprobe_opcode_t *slot, int dirty);
300 /* sleep-less address checking routine */
301 extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
302 unsigned long addr);
303
304 #define DEFINE_INSN_CACHE_OPS(__name) \
305 extern struct kprobe_insn_cache kprobe_##__name##_slots; \
306 \
307 static inline kprobe_opcode_t *get_##__name##_slot(void) \
308 { \
309 return __get_insn_slot(&kprobe_##__name##_slots); \
310 } \
311 \
312 static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
313 { \
314 __free_insn_slot(&kprobe_##__name##_slots, slot, dirty); \
315 } \
316 \
317 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \
318 { \
319 return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \
320 }
321 #define KPROBE_INSN_PAGE_SYM "kprobe_insn_page"
322 #define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page"
323 int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
324 unsigned long *value, char *type, char *sym);
325 #else /* !__ARCH_WANT_KPROBES_INSN_SLOT */
326 #define DEFINE_INSN_CACHE_OPS(__name) \
327 static inline bool is_kprobe_##__name##_slot(unsigned long addr) \
328 { \
329 return 0; \
330 }
331 #endif
332
333 DEFINE_INSN_CACHE_OPS(insn);
334
335 #ifdef CONFIG_OPTPROBES
336 /*
337 * Internal structure for direct jump optimized probe
338 */
339 struct optimized_kprobe {
340 struct kprobe kp;
341 struct list_head list; /* list for optimizing queue */
342 struct arch_optimized_insn optinsn;
343 };
344
345 /* Architecture dependent functions for direct jump optimization */
346 extern int arch_prepared_optinsn(struct arch_optimized_insn *optinsn);
347 extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
348 extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
349 struct kprobe *orig);
350 extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
351 extern void arch_optimize_kprobes(struct list_head *oplist);
352 extern void arch_unoptimize_kprobes(struct list_head *oplist,
353 struct list_head *done_list);
354 extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
355 extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
356 kprobe_opcode_t *addr);
357
358 extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
359
360 DEFINE_INSN_CACHE_OPS(optinsn);
361
362 extern void wait_for_kprobe_optimizer(void);
363 bool optprobe_queued_unopt(struct optimized_kprobe *op);
364 bool kprobe_disarmed(struct kprobe *p);
365 #else /* !CONFIG_OPTPROBES */
wait_for_kprobe_optimizer(void)366 static inline void wait_for_kprobe_optimizer(void) { }
367 #endif /* CONFIG_OPTPROBES */
368
369 #ifdef CONFIG_KPROBES_ON_FTRACE
370 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
371 struct ftrace_ops *ops, struct ftrace_regs *fregs);
372 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
373 /* Set when ftrace has been killed: kprobes on ftrace must be disabled for safety */
374 extern bool kprobe_ftrace_disabled __read_mostly;
375 extern void kprobe_ftrace_kill(void);
376 #else
arch_prepare_kprobe_ftrace(struct kprobe * p)377 static inline int arch_prepare_kprobe_ftrace(struct kprobe *p)
378 {
379 return -EINVAL;
380 }
kprobe_ftrace_kill(void)381 static inline void kprobe_ftrace_kill(void) {}
382 #endif /* CONFIG_KPROBES_ON_FTRACE */
383
384 /* Get the kprobe at this addr (if any) - called with preemption disabled */
385 struct kprobe *get_kprobe(void *addr);
386
387 /* kprobe_running() will just return the current_kprobe on this CPU */
kprobe_running(void)388 static inline struct kprobe *kprobe_running(void)
389 {
390 return __this_cpu_read(current_kprobe);
391 }
392
reset_current_kprobe(void)393 static inline void reset_current_kprobe(void)
394 {
395 __this_cpu_write(current_kprobe, NULL);
396 }
397
get_kprobe_ctlblk(void)398 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
399 {
400 return this_cpu_ptr(&kprobe_ctlblk);
401 }
402
403 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
404 kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry);
405
406 int register_kprobe(struct kprobe *p);
407 void unregister_kprobe(struct kprobe *p);
408 int register_kprobes(struct kprobe **kps, int num);
409 void unregister_kprobes(struct kprobe **kps, int num);
410
411 int register_kretprobe(struct kretprobe *rp);
412 void unregister_kretprobe(struct kretprobe *rp);
413 int register_kretprobes(struct kretprobe **rps, int num);
414 void unregister_kretprobes(struct kretprobe **rps, int num);
415
416 #if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)
417 #define kprobe_flush_task(tk) do {} while (0)
418 #else
419 void kprobe_flush_task(struct task_struct *tk);
420 #endif
421
422 void kprobe_free_init_mem(void);
423
424 int disable_kprobe(struct kprobe *kp);
425 int enable_kprobe(struct kprobe *kp);
426
427 void dump_kprobe(struct kprobe *kp);
428
429 void *alloc_insn_page(void);
430
431 void *alloc_optinsn_page(void);
432 void free_optinsn_page(void *page);
433
434 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
435 char *sym);
436
437 int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
438 char *type, char *sym);
439
440 int kprobe_exceptions_notify(struct notifier_block *self,
441 unsigned long val, void *data);
442
443 #else /* !CONFIG_KPROBES: */
444
kprobe_fault_handler(struct pt_regs * regs,int trapnr)445 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
446 {
447 return 0;
448 }
get_kprobe(void * addr)449 static inline struct kprobe *get_kprobe(void *addr)
450 {
451 return NULL;
452 }
kprobe_running(void)453 static inline struct kprobe *kprobe_running(void)
454 {
455 return NULL;
456 }
457 #define kprobe_busy_begin() do {} while (0)
458 #define kprobe_busy_end() do {} while (0)
459
register_kprobe(struct kprobe * p)460 static inline int register_kprobe(struct kprobe *p)
461 {
462 return -EOPNOTSUPP;
463 }
register_kprobes(struct kprobe ** kps,int num)464 static inline int register_kprobes(struct kprobe **kps, int num)
465 {
466 return -EOPNOTSUPP;
467 }
unregister_kprobe(struct kprobe * p)468 static inline void unregister_kprobe(struct kprobe *p)
469 {
470 }
unregister_kprobes(struct kprobe ** kps,int num)471 static inline void unregister_kprobes(struct kprobe **kps, int num)
472 {
473 }
register_kretprobe(struct kretprobe * rp)474 static inline int register_kretprobe(struct kretprobe *rp)
475 {
476 return -EOPNOTSUPP;
477 }
register_kretprobes(struct kretprobe ** rps,int num)478 static inline int register_kretprobes(struct kretprobe **rps, int num)
479 {
480 return -EOPNOTSUPP;
481 }
unregister_kretprobe(struct kretprobe * rp)482 static inline void unregister_kretprobe(struct kretprobe *rp)
483 {
484 }
unregister_kretprobes(struct kretprobe ** rps,int num)485 static inline void unregister_kretprobes(struct kretprobe **rps, int num)
486 {
487 }
kprobe_flush_task(struct task_struct * tk)488 static inline void kprobe_flush_task(struct task_struct *tk)
489 {
490 }
kprobe_free_init_mem(void)491 static inline void kprobe_free_init_mem(void)
492 {
493 }
kprobe_ftrace_kill(void)494 static inline void kprobe_ftrace_kill(void)
495 {
496 }
disable_kprobe(struct kprobe * kp)497 static inline int disable_kprobe(struct kprobe *kp)
498 {
499 return -EOPNOTSUPP;
500 }
enable_kprobe(struct kprobe * kp)501 static inline int enable_kprobe(struct kprobe *kp)
502 {
503 return -EOPNOTSUPP;
504 }
505
within_kprobe_blacklist(unsigned long addr)506 static inline bool within_kprobe_blacklist(unsigned long addr)
507 {
508 return true;
509 }
kprobe_get_kallsym(unsigned int symnum,unsigned long * value,char * type,char * sym)510 static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
511 char *type, char *sym)
512 {
513 return -ERANGE;
514 }
515 #endif /* CONFIG_KPROBES */
516
disable_kretprobe(struct kretprobe * rp)517 static inline int disable_kretprobe(struct kretprobe *rp)
518 {
519 return disable_kprobe(&rp->kp);
520 }
enable_kretprobe(struct kretprobe * rp)521 static inline int enable_kretprobe(struct kretprobe *rp)
522 {
523 return enable_kprobe(&rp->kp);
524 }
525
526 #ifndef CONFIG_KPROBES
is_kprobe_insn_slot(unsigned long addr)527 static inline bool is_kprobe_insn_slot(unsigned long addr)
528 {
529 return false;
530 }
531 #endif /* !CONFIG_KPROBES */
532
533 #ifndef CONFIG_OPTPROBES
is_kprobe_optinsn_slot(unsigned long addr)534 static inline bool is_kprobe_optinsn_slot(unsigned long addr)
535 {
536 return false;
537 }
538 #endif /* !CONFIG_OPTPROBES */
539
540 #ifdef CONFIG_KRETPROBES
541 #ifdef CONFIG_KRETPROBE_ON_RETHOOK
is_kretprobe_trampoline(unsigned long addr)542 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
543 {
544 return is_rethook_trampoline(addr);
545 }
546
547 static nokprobe_inline
kretprobe_find_ret_addr(struct task_struct * tsk,void * fp,struct llist_node ** cur)548 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
549 struct llist_node **cur)
550 {
551 return rethook_find_ret_addr(tsk, (unsigned long)fp, cur);
552 }
553 #else
is_kretprobe_trampoline(unsigned long addr)554 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
555 {
556 return (void *)addr == kretprobe_trampoline_addr();
557 }
558
559 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
560 struct llist_node **cur);
561 #endif
562 #else
is_kretprobe_trampoline(unsigned long addr)563 static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
564 {
565 return false;
566 }
567
568 static nokprobe_inline
kretprobe_find_ret_addr(struct task_struct * tsk,void * fp,struct llist_node ** cur)569 unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
570 struct llist_node **cur)
571 {
572 return 0;
573 }
574 #endif
575
576 /* Returns true if kprobes handled the fault */
kprobe_page_fault(struct pt_regs * regs,unsigned int trap)577 static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
578 unsigned int trap)
579 {
580 if (!IS_ENABLED(CONFIG_KPROBES))
581 return false;
582 if (user_mode(regs))
583 return false;
584 /*
585 * To be potentially processing a kprobe fault and to be allowed
586 * to call kprobe_running(), we have to be non-preemptible.
587 */
588 if (preemptible())
589 return false;
590 if (!kprobe_running())
591 return false;
592 return kprobe_fault_handler(regs, trap);
593 }
594
595 #endif /* _LINUX_KPROBES_H */
596