1 /* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
2 * Copyright (c) 2016 Facebook
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
8 #include <linux/kernel.h>
9 #include <linux/types.h>
10 #include <linux/slab.h>
11 #include <linux/bpf.h>
12 #include <linux/bpf_perf_event.h>
13 #include <linux/filter.h>
14 #include <linux/uaccess.h>
15 #include <linux/ctype.h>
19 * trace_call_bpf - invoke BPF program
21 * @ctx: opaque context pointer
23 * kprobe handlers execute BPF programs via this helper.
24 * Can be used from static tracepoints in the future.
26 * Return: BPF programs always return an integer which is interpreted by
28 * 0 - return from kprobe (event is filtered out)
29 * 1 - store kprobe event into ring buffer
30 * Other values are reserved and currently alias to 1
32 unsigned int trace_call_bpf(struct bpf_prog
*prog
, void *ctx
)
36 if (in_nmi()) /* not supported yet */
41 if (unlikely(__this_cpu_inc_return(bpf_prog_active
) != 1)) {
43 * since some bpf program is already running on this cpu,
44 * don't call into another bpf program (same or different)
45 * and don't send kprobe event into ring-buffer,
53 ret
= BPF_PROG_RUN(prog
, ctx
);
57 __this_cpu_dec(bpf_prog_active
);
62 EXPORT_SYMBOL_GPL(trace_call_bpf
);
64 BPF_CALL_3(bpf_probe_read
, void *, dst
, u32
, size
, const void *, unsafe_ptr
)
68 ret
= probe_kernel_read(dst
, unsafe_ptr
, size
);
69 if (unlikely(ret
< 0))
75 static const struct bpf_func_proto bpf_probe_read_proto
= {
76 .func
= bpf_probe_read
,
78 .ret_type
= RET_INTEGER
,
79 .arg1_type
= ARG_PTR_TO_UNINIT_MEM
,
80 .arg2_type
= ARG_CONST_SIZE
,
81 .arg3_type
= ARG_ANYTHING
,
84 BPF_CALL_3(bpf_probe_write_user
, void *, unsafe_ptr
, const void *, src
,
88 * Ensure we're in user context which is safe for the helper to
89 * run. This helper has no business in a kthread.
91 * access_ok() should prevent writing to non-user memory, but in
92 * some situations (nommu, temporary switch, etc) access_ok() does
93 * not provide enough validation, hence the check on KERNEL_DS.
96 if (unlikely(in_interrupt() ||
97 current
->flags
& (PF_KTHREAD
| PF_EXITING
)))
99 if (unlikely(uaccess_kernel()))
101 if (!access_ok(VERIFY_WRITE
, unsafe_ptr
, size
))
104 return probe_kernel_write(unsafe_ptr
, src
, size
);
107 static const struct bpf_func_proto bpf_probe_write_user_proto
= {
108 .func
= bpf_probe_write_user
,
110 .ret_type
= RET_INTEGER
,
111 .arg1_type
= ARG_ANYTHING
,
112 .arg2_type
= ARG_PTR_TO_MEM
,
113 .arg3_type
= ARG_CONST_SIZE
,
116 static const struct bpf_func_proto
*bpf_get_probe_write_proto(void)
118 pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!",
119 current
->comm
, task_pid_nr(current
));
121 return &bpf_probe_write_user_proto
;
125 * Only limited trace_printk() conversion specifiers allowed:
126 * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %s
128 BPF_CALL_5(bpf_trace_printk
, char *, fmt
, u32
, fmt_size
, u64
, arg1
,
129 u64
, arg2
, u64
, arg3
)
131 bool str_seen
= false;
139 * bpf_check()->check_func_arg()->check_stack_boundary()
140 * guarantees that fmt points to bpf program stack,
141 * fmt_size bytes of it were initialized and fmt_size > 0
143 if (fmt
[--fmt_size
] != 0)
146 /* check format string for allowed specifiers */
147 for (i
= 0; i
< fmt_size
; i
++) {
148 if ((!isprint(fmt
[i
]) && !isspace(fmt
[i
])) || !isascii(fmt
[i
]))
157 /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
162 } else if (fmt
[i
] == 'p' || fmt
[i
] == 's') {
165 if (!isspace(fmt
[i
]) && !ispunct(fmt
[i
]) && fmt
[i
] != 0)
168 if (fmt
[i
- 1] == 's') {
170 /* allow only one '%s' per fmt string */
189 strncpy_from_unsafe(buf
,
190 (void *) (long) unsafe_addr
,
201 if (fmt
[i
] != 'i' && fmt
[i
] != 'd' &&
202 fmt
[i
] != 'u' && fmt
[i
] != 'x')
207 return __trace_printk(1/* fake ip will not be printed */, fmt
,
208 mod
[0] == 2 ? arg1
: mod
[0] == 1 ? (long) arg1
: (u32
) arg1
,
209 mod
[1] == 2 ? arg2
: mod
[1] == 1 ? (long) arg2
: (u32
) arg2
,
210 mod
[2] == 2 ? arg3
: mod
[2] == 1 ? (long) arg3
: (u32
) arg3
);
213 static const struct bpf_func_proto bpf_trace_printk_proto
= {
214 .func
= bpf_trace_printk
,
216 .ret_type
= RET_INTEGER
,
217 .arg1_type
= ARG_PTR_TO_MEM
,
218 .arg2_type
= ARG_CONST_SIZE
,
221 const struct bpf_func_proto
*bpf_get_trace_printk_proto(void)
224 * this program might be calling bpf_trace_printk,
225 * so allocate per-cpu printk buffers
227 trace_printk_init_buffers();
229 return &bpf_trace_printk_proto
;
232 BPF_CALL_2(bpf_perf_event_read
, struct bpf_map
*, map
, u64
, flags
)
234 struct bpf_array
*array
= container_of(map
, struct bpf_array
, map
);
235 unsigned int cpu
= smp_processor_id();
236 u64 index
= flags
& BPF_F_INDEX_MASK
;
237 struct bpf_event_entry
*ee
;
241 if (unlikely(flags
& ~(BPF_F_INDEX_MASK
)))
243 if (index
== BPF_F_CURRENT_CPU
)
245 if (unlikely(index
>= array
->map
.max_entries
))
248 ee
= READ_ONCE(array
->ptrs
[index
]);
252 err
= perf_event_read_local(ee
->event
, &value
);
254 * this api is ugly since we miss [-22..-2] range of valid
255 * counter values, but that's uapi
262 static const struct bpf_func_proto bpf_perf_event_read_proto
= {
263 .func
= bpf_perf_event_read
,
265 .ret_type
= RET_INTEGER
,
266 .arg1_type
= ARG_CONST_MAP_PTR
,
267 .arg2_type
= ARG_ANYTHING
,
270 static DEFINE_PER_CPU(struct perf_sample_data
, bpf_sd
);
272 static __always_inline u64
273 __bpf_perf_event_output(struct pt_regs
*regs
, struct bpf_map
*map
,
274 u64 flags
, struct perf_raw_record
*raw
)
276 struct bpf_array
*array
= container_of(map
, struct bpf_array
, map
);
277 struct perf_sample_data
*sd
= this_cpu_ptr(&bpf_sd
);
278 unsigned int cpu
= smp_processor_id();
279 u64 index
= flags
& BPF_F_INDEX_MASK
;
280 struct bpf_event_entry
*ee
;
281 struct perf_event
*event
;
283 if (index
== BPF_F_CURRENT_CPU
)
285 if (unlikely(index
>= array
->map
.max_entries
))
288 ee
= READ_ONCE(array
->ptrs
[index
]);
293 if (unlikely(event
->attr
.type
!= PERF_TYPE_SOFTWARE
||
294 event
->attr
.config
!= PERF_COUNT_SW_BPF_OUTPUT
))
297 if (unlikely(event
->oncpu
!= cpu
))
300 perf_sample_data_init(sd
, 0, 0);
302 perf_event_output(event
, sd
, regs
);
306 BPF_CALL_5(bpf_perf_event_output
, struct pt_regs
*, regs
, struct bpf_map
*, map
,
307 u64
, flags
, void *, data
, u64
, size
)
309 struct perf_raw_record raw
= {
316 if (unlikely(flags
& ~(BPF_F_INDEX_MASK
)))
319 return __bpf_perf_event_output(regs
, map
, flags
, &raw
);
322 static const struct bpf_func_proto bpf_perf_event_output_proto
= {
323 .func
= bpf_perf_event_output
,
325 .ret_type
= RET_INTEGER
,
326 .arg1_type
= ARG_PTR_TO_CTX
,
327 .arg2_type
= ARG_CONST_MAP_PTR
,
328 .arg3_type
= ARG_ANYTHING
,
329 .arg4_type
= ARG_PTR_TO_MEM
,
330 .arg5_type
= ARG_CONST_SIZE
,
333 static DEFINE_PER_CPU(struct pt_regs
, bpf_pt_regs
);
335 u64
bpf_event_output(struct bpf_map
*map
, u64 flags
, void *meta
, u64 meta_size
,
336 void *ctx
, u64 ctx_size
, bpf_ctx_copy_t ctx_copy
)
338 struct pt_regs
*regs
= this_cpu_ptr(&bpf_pt_regs
);
339 struct perf_raw_frag frag
= {
344 struct perf_raw_record raw
= {
347 .next
= ctx_size
? &frag
: NULL
,
354 perf_fetch_caller_regs(regs
);
356 return __bpf_perf_event_output(regs
, map
, flags
, &raw
);
359 BPF_CALL_0(bpf_get_current_task
)
361 return (long) current
;
364 static const struct bpf_func_proto bpf_get_current_task_proto
= {
365 .func
= bpf_get_current_task
,
367 .ret_type
= RET_INTEGER
,
370 BPF_CALL_2(bpf_current_task_under_cgroup
, struct bpf_map
*, map
, u32
, idx
)
372 struct bpf_array
*array
= container_of(map
, struct bpf_array
, map
);
375 if (unlikely(in_interrupt()))
377 if (unlikely(idx
>= array
->map
.max_entries
))
380 cgrp
= READ_ONCE(array
->ptrs
[idx
]);
384 return task_under_cgroup_hierarchy(current
, cgrp
);
387 static const struct bpf_func_proto bpf_current_task_under_cgroup_proto
= {
388 .func
= bpf_current_task_under_cgroup
,
390 .ret_type
= RET_INTEGER
,
391 .arg1_type
= ARG_CONST_MAP_PTR
,
392 .arg2_type
= ARG_ANYTHING
,
395 BPF_CALL_3(bpf_probe_read_str
, void *, dst
, u32
, size
,
396 const void *, unsafe_ptr
)
401 * The strncpy_from_unsafe() call will likely not fill the entire
402 * buffer, but that's okay in this circumstance as we're probing
403 * arbitrary memory anyway similar to bpf_probe_read() and might
404 * as well probe the stack. Thus, memory is explicitly cleared
405 * only in error case, so that improper users ignoring return
406 * code altogether don't copy garbage; otherwise length of string
407 * is returned that can be used for bpf_perf_event_output() et al.
409 ret
= strncpy_from_unsafe(dst
, unsafe_ptr
, size
);
410 if (unlikely(ret
< 0))
411 memset(dst
, 0, size
);
416 static const struct bpf_func_proto bpf_probe_read_str_proto
= {
417 .func
= bpf_probe_read_str
,
419 .ret_type
= RET_INTEGER
,
420 .arg1_type
= ARG_PTR_TO_UNINIT_MEM
,
421 .arg2_type
= ARG_CONST_SIZE
,
422 .arg3_type
= ARG_ANYTHING
,
425 static const struct bpf_func_proto
*tracing_func_proto(enum bpf_func_id func_id
)
428 case BPF_FUNC_map_lookup_elem
:
429 return &bpf_map_lookup_elem_proto
;
430 case BPF_FUNC_map_update_elem
:
431 return &bpf_map_update_elem_proto
;
432 case BPF_FUNC_map_delete_elem
:
433 return &bpf_map_delete_elem_proto
;
434 case BPF_FUNC_probe_read
:
435 return &bpf_probe_read_proto
;
436 case BPF_FUNC_ktime_get_ns
:
437 return &bpf_ktime_get_ns_proto
;
438 case BPF_FUNC_tail_call
:
439 return &bpf_tail_call_proto
;
440 case BPF_FUNC_get_current_pid_tgid
:
441 return &bpf_get_current_pid_tgid_proto
;
442 case BPF_FUNC_get_current_task
:
443 return &bpf_get_current_task_proto
;
444 case BPF_FUNC_get_current_uid_gid
:
445 return &bpf_get_current_uid_gid_proto
;
446 case BPF_FUNC_get_current_comm
:
447 return &bpf_get_current_comm_proto
;
448 case BPF_FUNC_trace_printk
:
449 return bpf_get_trace_printk_proto();
450 case BPF_FUNC_get_smp_processor_id
:
451 return &bpf_get_smp_processor_id_proto
;
452 case BPF_FUNC_get_numa_node_id
:
453 return &bpf_get_numa_node_id_proto
;
454 case BPF_FUNC_perf_event_read
:
455 return &bpf_perf_event_read_proto
;
456 case BPF_FUNC_probe_write_user
:
457 return bpf_get_probe_write_proto();
458 case BPF_FUNC_current_task_under_cgroup
:
459 return &bpf_current_task_under_cgroup_proto
;
460 case BPF_FUNC_get_prandom_u32
:
461 return &bpf_get_prandom_u32_proto
;
462 case BPF_FUNC_probe_read_str
:
463 return &bpf_probe_read_str_proto
;
469 static const struct bpf_func_proto
*kprobe_prog_func_proto(enum bpf_func_id func_id
)
472 case BPF_FUNC_perf_event_output
:
473 return &bpf_perf_event_output_proto
;
474 case BPF_FUNC_get_stackid
:
475 return &bpf_get_stackid_proto
;
477 return tracing_func_proto(func_id
);
481 /* bpf+kprobe programs can access fields of 'struct pt_regs' */
482 static bool kprobe_prog_is_valid_access(int off
, int size
, enum bpf_access_type type
,
483 struct bpf_insn_access_aux
*info
)
485 if (off
< 0 || off
>= sizeof(struct pt_regs
))
487 if (type
!= BPF_READ
)
492 * Assertion for 32 bit to make sure last 8 byte access
493 * (BPF_DW) to the last 4 byte member is disallowed.
495 if (off
+ size
> sizeof(struct pt_regs
))
501 const struct bpf_verifier_ops kprobe_prog_ops
= {
502 .get_func_proto
= kprobe_prog_func_proto
,
503 .is_valid_access
= kprobe_prog_is_valid_access
,
506 BPF_CALL_5(bpf_perf_event_output_tp
, void *, tp_buff
, struct bpf_map
*, map
,
507 u64
, flags
, void *, data
, u64
, size
)
509 struct pt_regs
*regs
= *(struct pt_regs
**)tp_buff
;
512 * r1 points to perf tracepoint buffer where first 8 bytes are hidden
513 * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
514 * from there and call the same bpf_perf_event_output() helper inline.
516 return ____bpf_perf_event_output(regs
, map
, flags
, data
, size
);
519 static const struct bpf_func_proto bpf_perf_event_output_proto_tp
= {
520 .func
= bpf_perf_event_output_tp
,
522 .ret_type
= RET_INTEGER
,
523 .arg1_type
= ARG_PTR_TO_CTX
,
524 .arg2_type
= ARG_CONST_MAP_PTR
,
525 .arg3_type
= ARG_ANYTHING
,
526 .arg4_type
= ARG_PTR_TO_MEM
,
527 .arg5_type
= ARG_CONST_SIZE
,
530 BPF_CALL_3(bpf_get_stackid_tp
, void *, tp_buff
, struct bpf_map
*, map
,
533 struct pt_regs
*regs
= *(struct pt_regs
**)tp_buff
;
536 * Same comment as in bpf_perf_event_output_tp(), only that this time
537 * the other helper's function body cannot be inlined due to being
538 * external, thus we need to call raw helper function.
540 return bpf_get_stackid((unsigned long) regs
, (unsigned long) map
,
544 static const struct bpf_func_proto bpf_get_stackid_proto_tp
= {
545 .func
= bpf_get_stackid_tp
,
547 .ret_type
= RET_INTEGER
,
548 .arg1_type
= ARG_PTR_TO_CTX
,
549 .arg2_type
= ARG_CONST_MAP_PTR
,
550 .arg3_type
= ARG_ANYTHING
,
553 static const struct bpf_func_proto
*tp_prog_func_proto(enum bpf_func_id func_id
)
556 case BPF_FUNC_perf_event_output
:
557 return &bpf_perf_event_output_proto_tp
;
558 case BPF_FUNC_get_stackid
:
559 return &bpf_get_stackid_proto_tp
;
561 return tracing_func_proto(func_id
);
565 static bool tp_prog_is_valid_access(int off
, int size
, enum bpf_access_type type
,
566 struct bpf_insn_access_aux
*info
)
568 if (off
< sizeof(void *) || off
>= PERF_MAX_TRACE_SIZE
)
570 if (type
!= BPF_READ
)
575 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE
% sizeof(__u64
));
579 const struct bpf_verifier_ops tracepoint_prog_ops
= {
580 .get_func_proto
= tp_prog_func_proto
,
581 .is_valid_access
= tp_prog_is_valid_access
,
584 static bool pe_prog_is_valid_access(int off
, int size
, enum bpf_access_type type
,
585 struct bpf_insn_access_aux
*info
)
587 const int size_sp
= FIELD_SIZEOF(struct bpf_perf_event_data
,
590 if (off
< 0 || off
>= sizeof(struct bpf_perf_event_data
))
592 if (type
!= BPF_READ
)
598 case bpf_ctx_range(struct bpf_perf_event_data
, sample_period
):
599 bpf_ctx_record_field_size(info
, size_sp
);
600 if (!bpf_ctx_narrow_access_ok(off
, size
, size_sp
))
604 if (size
!= sizeof(long))
611 static u32
pe_prog_convert_ctx_access(enum bpf_access_type type
,
612 const struct bpf_insn
*si
,
613 struct bpf_insn
*insn_buf
,
614 struct bpf_prog
*prog
, u32
*target_size
)
616 struct bpf_insn
*insn
= insn_buf
;
619 case offsetof(struct bpf_perf_event_data
, sample_period
):
620 *insn
++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern
,
621 data
), si
->dst_reg
, si
->src_reg
,
622 offsetof(struct bpf_perf_event_data_kern
, data
));
623 *insn
++ = BPF_LDX_MEM(BPF_DW
, si
->dst_reg
, si
->dst_reg
,
624 bpf_target_off(struct perf_sample_data
, period
, 8,
628 *insn
++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern
,
629 regs
), si
->dst_reg
, si
->src_reg
,
630 offsetof(struct bpf_perf_event_data_kern
, regs
));
631 *insn
++ = BPF_LDX_MEM(BPF_SIZEOF(long), si
->dst_reg
, si
->dst_reg
,
636 return insn
- insn_buf
;
639 const struct bpf_verifier_ops perf_event_prog_ops
= {
640 .get_func_proto
= tp_prog_func_proto
,
641 .is_valid_access
= pe_prog_is_valid_access
,
642 .convert_ctx_access
= pe_prog_convert_ctx_access
,