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 * limited trace_printk()
126 * only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed
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] != 'd' && fmt[i] != 'u' && fmt[i] != 'x')
206 return __trace_printk(1/* fake ip will not be printed */, fmt,
207 mod[0] == 2 ? arg1 : mod[0] == 1 ? (long) arg1 : (u32) arg1,
208 mod[1] == 2 ? arg2 : mod[1] == 1 ? (long) arg2 : (u32) arg2,
209 mod[2] == 2 ? arg3 : mod[2] == 1 ? (long) arg3 : (u32) arg3);
212 static const struct bpf_func_proto bpf_trace_printk_proto = {
213 .func = bpf_trace_printk,
215 .ret_type = RET_INTEGER,
216 .arg1_type = ARG_PTR_TO_MEM,
217 .arg2_type = ARG_CONST_SIZE,
220 const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
223 * this program might be calling bpf_trace_printk,
224 * so allocate per-cpu printk buffers
226 trace_printk_init_buffers();
228 return &bpf_trace_printk_proto;
231 BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags)
233 struct bpf_array *array = container_of(map, struct bpf_array, map);
234 unsigned int cpu = smp_processor_id();
235 u64 index = flags & BPF_F_INDEX_MASK;
236 struct bpf_event_entry *ee;
240 if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
242 if (index == BPF_F_CURRENT_CPU)
244 if (unlikely(index >= array->map.max_entries))
247 ee = READ_ONCE(array->ptrs[index]);
251 err = perf_event_read_local(ee->event, &value);
253 * this api is ugly since we miss [-22..-2] range of valid
254 * counter values, but that's uapi
261 static const struct bpf_func_proto bpf_perf_event_read_proto = {
262 .func = bpf_perf_event_read,
264 .ret_type = RET_INTEGER,
265 .arg1_type = ARG_CONST_MAP_PTR,
266 .arg2_type = ARG_ANYTHING,
269 static DEFINE_PER_CPU(struct perf_sample_data, bpf_sd);
271 static __always_inline u64
272 __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
273 u64 flags, struct perf_raw_record *raw)
275 struct bpf_array *array = container_of(map, struct bpf_array, map);
276 struct perf_sample_data *sd = this_cpu_ptr(&bpf_sd);
277 unsigned int cpu = smp_processor_id();
278 u64 index = flags & BPF_F_INDEX_MASK;
279 struct bpf_event_entry *ee;
280 struct perf_event *event;
282 if (index == BPF_F_CURRENT_CPU)
284 if (unlikely(index >= array->map.max_entries))
287 ee = READ_ONCE(array->ptrs[index]);
292 if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
293 event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
296 if (unlikely(event->oncpu != cpu))
299 perf_sample_data_init(sd, 0, 0);
301 perf_event_output(event, sd, regs);
305 BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
306 u64, flags, void *, data, u64, size)
308 struct perf_raw_record raw = {
315 if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
318 return __bpf_perf_event_output(regs, map, flags, &raw);
321 static const struct bpf_func_proto bpf_perf_event_output_proto = {
322 .func = bpf_perf_event_output,
324 .ret_type = RET_INTEGER,
325 .arg1_type = ARG_PTR_TO_CTX,
326 .arg2_type = ARG_CONST_MAP_PTR,
327 .arg3_type = ARG_ANYTHING,
328 .arg4_type = ARG_PTR_TO_MEM,
329 .arg5_type = ARG_CONST_SIZE,
332 static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
334 u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
335 void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
337 struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs);
338 struct perf_raw_frag frag = {
343 struct perf_raw_record raw = {
346 .next = ctx_size ? &frag : NULL,
353 perf_fetch_caller_regs(regs);
355 return __bpf_perf_event_output(regs, map, flags, &raw);
358 BPF_CALL_0(bpf_get_current_task)
360 return (long) current;
363 static const struct bpf_func_proto bpf_get_current_task_proto = {
364 .func = bpf_get_current_task,
366 .ret_type = RET_INTEGER,
369 BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
371 struct bpf_array *array = container_of(map, struct bpf_array, map);
374 if (unlikely(in_interrupt()))
376 if (unlikely(idx >= array->map.max_entries))
379 cgrp = READ_ONCE(array->ptrs[idx]);
383 return task_under_cgroup_hierarchy(current, cgrp);
386 static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
387 .func = bpf_current_task_under_cgroup,
389 .ret_type = RET_INTEGER,
390 .arg1_type = ARG_CONST_MAP_PTR,
391 .arg2_type = ARG_ANYTHING,
394 BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
395 const void *, unsafe_ptr)
400 * The strncpy_from_unsafe() call will likely not fill the entire
401 * buffer, but that's okay in this circumstance as we're probing
402 * arbitrary memory anyway similar to bpf_probe_read() and might
403 * as well probe the stack. Thus, memory is explicitly cleared
404 * only in error case, so that improper users ignoring return
405 * code altogether don't copy garbage; otherwise length of string
406 * is returned that can be used for bpf_perf_event_output() et al.
408 ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
409 if (unlikely(ret < 0))
410 memset(dst, 0, size);
415 static const struct bpf_func_proto bpf_probe_read_str_proto = {
416 .func = bpf_probe_read_str,
418 .ret_type = RET_INTEGER,
419 .arg1_type = ARG_PTR_TO_UNINIT_MEM,
420 .arg2_type = ARG_CONST_SIZE,
421 .arg3_type = ARG_ANYTHING,
424 static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)
427 case BPF_FUNC_map_lookup_elem:
428 return &bpf_map_lookup_elem_proto;
429 case BPF_FUNC_map_update_elem:
430 return &bpf_map_update_elem_proto;
431 case BPF_FUNC_map_delete_elem:
432 return &bpf_map_delete_elem_proto;
433 case BPF_FUNC_probe_read:
434 return &bpf_probe_read_proto;
435 case BPF_FUNC_ktime_get_ns:
436 return &bpf_ktime_get_ns_proto;
437 case BPF_FUNC_tail_call:
438 return &bpf_tail_call_proto;
439 case BPF_FUNC_get_current_pid_tgid:
440 return &bpf_get_current_pid_tgid_proto;
441 case BPF_FUNC_get_current_task:
442 return &bpf_get_current_task_proto;
443 case BPF_FUNC_get_current_uid_gid:
444 return &bpf_get_current_uid_gid_proto;
445 case BPF_FUNC_get_current_comm:
446 return &bpf_get_current_comm_proto;
447 case BPF_FUNC_trace_printk:
448 return bpf_get_trace_printk_proto();
449 case BPF_FUNC_get_smp_processor_id:
450 return &bpf_get_smp_processor_id_proto;
451 case BPF_FUNC_get_numa_node_id:
452 return &bpf_get_numa_node_id_proto;
453 case BPF_FUNC_perf_event_read:
454 return &bpf_perf_event_read_proto;
455 case BPF_FUNC_probe_write_user:
456 return bpf_get_probe_write_proto();
457 case BPF_FUNC_current_task_under_cgroup:
458 return &bpf_current_task_under_cgroup_proto;
459 case BPF_FUNC_get_prandom_u32:
460 return &bpf_get_prandom_u32_proto;
461 case BPF_FUNC_probe_read_str:
462 return &bpf_probe_read_str_proto;
468 static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
471 case BPF_FUNC_perf_event_output:
472 return &bpf_perf_event_output_proto;
473 case BPF_FUNC_get_stackid:
474 return &bpf_get_stackid_proto;
476 return tracing_func_proto(func_id);
480 /* bpf+kprobe programs can access fields of 'struct pt_regs' */
481 static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
482 enum bpf_reg_type *reg_type, int *ctx_field_size)
484 if (off < 0 || off >= sizeof(struct pt_regs))
486 if (type != BPF_READ)
491 * Assertion for 32 bit to make sure last 8 byte access
492 * (BPF_DW) to the last 4 byte member is disallowed.
494 if (off + size > sizeof(struct pt_regs))
500 const struct bpf_verifier_ops kprobe_prog_ops = {
501 .get_func_proto = kprobe_prog_func_proto,
502 .is_valid_access = kprobe_prog_is_valid_access,
505 BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map,
506 u64, flags, void *, data, u64, size)
508 struct pt_regs *regs = *(struct pt_regs **)tp_buff;
511 * r1 points to perf tracepoint buffer where first 8 bytes are hidden
512 * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
513 * from there and call the same bpf_perf_event_output() helper inline.
515 return ____bpf_perf_event_output(regs, map, flags, data, size);
518 static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
519 .func = bpf_perf_event_output_tp,
521 .ret_type = RET_INTEGER,
522 .arg1_type = ARG_PTR_TO_CTX,
523 .arg2_type = ARG_CONST_MAP_PTR,
524 .arg3_type = ARG_ANYTHING,
525 .arg4_type = ARG_PTR_TO_MEM,
526 .arg5_type = ARG_CONST_SIZE,
529 BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map,
532 struct pt_regs *regs = *(struct pt_regs **)tp_buff;
535 * Same comment as in bpf_perf_event_output_tp(), only that this time
536 * the other helper's function body cannot be inlined due to being
537 * external, thus we need to call raw helper function.
539 return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
543 static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
544 .func = bpf_get_stackid_tp,
546 .ret_type = RET_INTEGER,
547 .arg1_type = ARG_PTR_TO_CTX,
548 .arg2_type = ARG_CONST_MAP_PTR,
549 .arg3_type = ARG_ANYTHING,
552 static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
555 case BPF_FUNC_perf_event_output:
556 return &bpf_perf_event_output_proto_tp;
557 case BPF_FUNC_get_stackid:
558 return &bpf_get_stackid_proto_tp;
560 return tracing_func_proto(func_id);
564 static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,
565 enum bpf_reg_type *reg_type, int *ctx_field_size)
567 if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)
569 if (type != BPF_READ)
574 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64));
578 const struct bpf_verifier_ops tracepoint_prog_ops = {
579 .get_func_proto = tp_prog_func_proto,
580 .is_valid_access = tp_prog_is_valid_access,
583 static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
584 enum bpf_reg_type *reg_type, int *ctx_field_size)
586 int sample_period_off;
588 if (off < 0 || off >= sizeof(struct bpf_perf_event_data))
590 if (type != BPF_READ)
595 /* permit 1, 2, 4 byte narrower and 8 normal read access to sample_period */
596 sample_period_off = offsetof(struct bpf_perf_event_data, sample_period);
597 if (off >= sample_period_off && off < sample_period_off + sizeof(__u64)) {
599 #ifdef __LITTLE_ENDIAN
600 return (off & 0x7) == 0 && size <= 8 && (size & (size - 1)) == 0;
602 return ((off & 0x7) + size) == 8 && size <= 8 && (size & (size - 1)) == 0;
605 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)
616 struct bpf_insn *insn = insn_buf;
619 case offsetof(struct bpf_perf_event_data, sample_period):
620 BUILD_BUG_ON(FIELD_SIZEOF(struct perf_sample_data, period) != sizeof(u64));
622 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
623 data), si->dst_reg, si->src_reg,
624 offsetof(struct bpf_perf_event_data_kern, data));
625 *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
626 offsetof(struct perf_sample_data, period));
629 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
630 regs), si->dst_reg, si->src_reg,
631 offsetof(struct bpf_perf_event_data_kern, regs));
632 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), si->dst_reg, si->dst_reg,
637 return insn - insn_buf;
640 const struct bpf_verifier_ops perf_event_prog_ops = {
641 .get_func_proto = tp_prog_func_proto,
642 .is_valid_access = pe_prog_is_valid_access,
643 .convert_ctx_access = pe_prog_convert_ctx_access,