1 /* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com 2 * Copyright (c) 2016 Facebook 3 * 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. 7 */ 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> 16 #include "trace.h" 17 18 /** 19 * trace_call_bpf - invoke BPF program 20 * @prog: BPF program 21 * @ctx: opaque context pointer 22 * 23 * kprobe handlers execute BPF programs via this helper. 24 * Can be used from static tracepoints in the future. 25 * 26 * Return: BPF programs always return an integer which is interpreted by 27 * kprobe handler as: 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 31 */ 32 unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx) 33 { 34 unsigned int ret; 35 36 if (in_nmi()) /* not supported yet */ 37 return 1; 38 39 preempt_disable(); 40 41 if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) { 42 /* 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, 46 * so return zero here 47 */ 48 ret = 0; 49 goto out; 50 } 51 52 rcu_read_lock(); 53 ret = BPF_PROG_RUN(prog, ctx); 54 rcu_read_unlock(); 55 56 out: 57 __this_cpu_dec(bpf_prog_active); 58 preempt_enable(); 59 60 return ret; 61 } 62 EXPORT_SYMBOL_GPL(trace_call_bpf); 63 64 BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr) 65 { 66 int ret; 67 68 ret = probe_kernel_read(dst, unsafe_ptr, size); 69 if (unlikely(ret < 0)) 70 memset(dst, 0, size); 71 72 return ret; 73 } 74 75 static const struct bpf_func_proto bpf_probe_read_proto = { 76 .func = bpf_probe_read, 77 .gpl_only = true, 78 .ret_type = RET_INTEGER, 79 .arg1_type = ARG_PTR_TO_RAW_STACK, 80 .arg2_type = ARG_CONST_STACK_SIZE, 81 .arg3_type = ARG_ANYTHING, 82 }; 83 84 BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, 85 u32, size) 86 { 87 /* 88 * Ensure we're in user context which is safe for the helper to 89 * run. This helper has no business in a kthread. 90 * 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. 94 */ 95 96 if (unlikely(in_interrupt() || 97 current->flags & (PF_KTHREAD | PF_EXITING))) 98 return -EPERM; 99 if (unlikely(segment_eq(get_fs(), KERNEL_DS))) 100 return -EPERM; 101 if (!access_ok(VERIFY_WRITE, unsafe_ptr, size)) 102 return -EPERM; 103 104 return probe_kernel_write(unsafe_ptr, src, size); 105 } 106 107 static const struct bpf_func_proto bpf_probe_write_user_proto = { 108 .func = bpf_probe_write_user, 109 .gpl_only = true, 110 .ret_type = RET_INTEGER, 111 .arg1_type = ARG_ANYTHING, 112 .arg2_type = ARG_PTR_TO_STACK, 113 .arg3_type = ARG_CONST_STACK_SIZE, 114 }; 115 116 static const struct bpf_func_proto *bpf_get_probe_write_proto(void) 117 { 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)); 120 121 return &bpf_probe_write_user_proto; 122 } 123 124 /* 125 * limited trace_printk() 126 * only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed 127 */ 128 BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, 129 u64, arg2, u64, arg3) 130 { 131 bool str_seen = false; 132 int mod[3] = {}; 133 int fmt_cnt = 0; 134 u64 unsafe_addr; 135 char buf[64]; 136 int i; 137 138 /* 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 > 0 142 */ 143 if (fmt[--fmt_size] != 0) 144 return -EINVAL; 145 146 /* 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])) 149 return -EINVAL; 150 151 if (fmt[i] != '%') 152 continue; 153 154 if (fmt_cnt >= 3) 155 return -EINVAL; 156 157 /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ 158 i++; 159 if (fmt[i] == 'l') { 160 mod[fmt_cnt]++; 161 i++; 162 } else if (fmt[i] == 'p' || fmt[i] == 's') { 163 mod[fmt_cnt]++; 164 i++; 165 if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0) 166 return -EINVAL; 167 fmt_cnt++; 168 if (fmt[i - 1] == 's') { 169 if (str_seen) 170 /* allow only one '%s' per fmt string */ 171 return -EINVAL; 172 str_seen = true; 173 174 switch (fmt_cnt) { 175 case 1: 176 unsafe_addr = arg1; 177 arg1 = (long) buf; 178 break; 179 case 2: 180 unsafe_addr = arg2; 181 arg2 = (long) buf; 182 break; 183 case 3: 184 unsafe_addr = arg3; 185 arg3 = (long) buf; 186 break; 187 } 188 buf[0] = 0; 189 strncpy_from_unsafe(buf, 190 (void *) (long) unsafe_addr, 191 sizeof(buf)); 192 } 193 continue; 194 } 195 196 if (fmt[i] == 'l') { 197 mod[fmt_cnt]++; 198 i++; 199 } 200 201 if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x') 202 return -EINVAL; 203 fmt_cnt++; 204 } 205 206 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); 210 } 211 212 static const struct bpf_func_proto bpf_trace_printk_proto = { 213 .func = bpf_trace_printk, 214 .gpl_only = true, 215 .ret_type = RET_INTEGER, 216 .arg1_type = ARG_PTR_TO_STACK, 217 .arg2_type = ARG_CONST_STACK_SIZE, 218 }; 219 220 const struct bpf_func_proto *bpf_get_trace_printk_proto(void) 221 { 222 /* 223 * this program might be calling bpf_trace_printk, 224 * so allocate per-cpu printk buffers 225 */ 226 trace_printk_init_buffers(); 227 228 return &bpf_trace_printk_proto; 229 } 230 231 BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags) 232 { 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; 237 struct perf_event *event; 238 239 if (unlikely(flags & ~(BPF_F_INDEX_MASK))) 240 return -EINVAL; 241 if (index == BPF_F_CURRENT_CPU) 242 index = cpu; 243 if (unlikely(index >= array->map.max_entries)) 244 return -E2BIG; 245 246 ee = READ_ONCE(array->ptrs[index]); 247 if (!ee) 248 return -ENOENT; 249 250 event = ee->event; 251 if (unlikely(event->attr.type != PERF_TYPE_HARDWARE && 252 event->attr.type != PERF_TYPE_RAW)) 253 return -EINVAL; 254 255 /* make sure event is local and doesn't have pmu::count */ 256 if (unlikely(event->oncpu != cpu || event->pmu->count)) 257 return -EINVAL; 258 259 /* 260 * we don't know if the function is run successfully by the 261 * return value. It can be judged in other places, such as 262 * eBPF programs. 263 */ 264 return perf_event_read_local(event); 265 } 266 267 static const struct bpf_func_proto bpf_perf_event_read_proto = { 268 .func = bpf_perf_event_read, 269 .gpl_only = true, 270 .ret_type = RET_INTEGER, 271 .arg1_type = ARG_CONST_MAP_PTR, 272 .arg2_type = ARG_ANYTHING, 273 }; 274 275 static __always_inline u64 276 __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map, 277 u64 flags, struct perf_raw_record *raw) 278 { 279 struct bpf_array *array = container_of(map, struct bpf_array, map); 280 unsigned int cpu = smp_processor_id(); 281 u64 index = flags & BPF_F_INDEX_MASK; 282 struct perf_sample_data sample_data; 283 struct bpf_event_entry *ee; 284 struct perf_event *event; 285 286 if (index == BPF_F_CURRENT_CPU) 287 index = cpu; 288 if (unlikely(index >= array->map.max_entries)) 289 return -E2BIG; 290 291 ee = READ_ONCE(array->ptrs[index]); 292 if (!ee) 293 return -ENOENT; 294 295 event = ee->event; 296 if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE || 297 event->attr.config != PERF_COUNT_SW_BPF_OUTPUT)) 298 return -EINVAL; 299 300 if (unlikely(event->oncpu != cpu)) 301 return -EOPNOTSUPP; 302 303 perf_sample_data_init(&sample_data, 0, 0); 304 sample_data.raw = raw; 305 perf_event_output(event, &sample_data, regs); 306 return 0; 307 } 308 309 BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map, 310 u64, flags, void *, data, u64, size) 311 { 312 struct perf_raw_record raw = { 313 .frag = { 314 .size = size, 315 .data = data, 316 }, 317 }; 318 319 if (unlikely(flags & ~(BPF_F_INDEX_MASK))) 320 return -EINVAL; 321 322 return __bpf_perf_event_output(regs, map, flags, &raw); 323 } 324 325 static const struct bpf_func_proto bpf_perf_event_output_proto = { 326 .func = bpf_perf_event_output, 327 .gpl_only = true, 328 .ret_type = RET_INTEGER, 329 .arg1_type = ARG_PTR_TO_CTX, 330 .arg2_type = ARG_CONST_MAP_PTR, 331 .arg3_type = ARG_ANYTHING, 332 .arg4_type = ARG_PTR_TO_STACK, 333 .arg5_type = ARG_CONST_STACK_SIZE, 334 }; 335 336 static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs); 337 338 u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, 339 void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy) 340 { 341 struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs); 342 struct perf_raw_frag frag = { 343 .copy = ctx_copy, 344 .size = ctx_size, 345 .data = ctx, 346 }; 347 struct perf_raw_record raw = { 348 .frag = { 349 { 350 .next = ctx_size ? &frag : NULL, 351 }, 352 .size = meta_size, 353 .data = meta, 354 }, 355 }; 356 357 perf_fetch_caller_regs(regs); 358 359 return __bpf_perf_event_output(regs, map, flags, &raw); 360 } 361 362 BPF_CALL_0(bpf_get_current_task) 363 { 364 return (long) current; 365 } 366 367 static const struct bpf_func_proto bpf_get_current_task_proto = { 368 .func = bpf_get_current_task, 369 .gpl_only = true, 370 .ret_type = RET_INTEGER, 371 }; 372 373 BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx) 374 { 375 struct bpf_array *array = container_of(map, struct bpf_array, map); 376 struct cgroup *cgrp; 377 378 if (unlikely(in_interrupt())) 379 return -EINVAL; 380 if (unlikely(idx >= array->map.max_entries)) 381 return -E2BIG; 382 383 cgrp = READ_ONCE(array->ptrs[idx]); 384 if (unlikely(!cgrp)) 385 return -EAGAIN; 386 387 return task_under_cgroup_hierarchy(current, cgrp); 388 } 389 390 static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = { 391 .func = bpf_current_task_under_cgroup, 392 .gpl_only = false, 393 .ret_type = RET_INTEGER, 394 .arg1_type = ARG_CONST_MAP_PTR, 395 .arg2_type = ARG_ANYTHING, 396 }; 397 398 static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id) 399 { 400 switch (func_id) { 401 case BPF_FUNC_map_lookup_elem: 402 return &bpf_map_lookup_elem_proto; 403 case BPF_FUNC_map_update_elem: 404 return &bpf_map_update_elem_proto; 405 case BPF_FUNC_map_delete_elem: 406 return &bpf_map_delete_elem_proto; 407 case BPF_FUNC_probe_read: 408 return &bpf_probe_read_proto; 409 case BPF_FUNC_ktime_get_ns: 410 return &bpf_ktime_get_ns_proto; 411 case BPF_FUNC_tail_call: 412 return &bpf_tail_call_proto; 413 case BPF_FUNC_get_current_pid_tgid: 414 return &bpf_get_current_pid_tgid_proto; 415 case BPF_FUNC_get_current_task: 416 return &bpf_get_current_task_proto; 417 case BPF_FUNC_get_current_uid_gid: 418 return &bpf_get_current_uid_gid_proto; 419 case BPF_FUNC_get_current_comm: 420 return &bpf_get_current_comm_proto; 421 case BPF_FUNC_trace_printk: 422 return bpf_get_trace_printk_proto(); 423 case BPF_FUNC_get_smp_processor_id: 424 return &bpf_get_smp_processor_id_proto; 425 case BPF_FUNC_perf_event_read: 426 return &bpf_perf_event_read_proto; 427 case BPF_FUNC_probe_write_user: 428 return bpf_get_probe_write_proto(); 429 case BPF_FUNC_current_task_under_cgroup: 430 return &bpf_current_task_under_cgroup_proto; 431 case BPF_FUNC_get_prandom_u32: 432 return &bpf_get_prandom_u32_proto; 433 default: 434 return NULL; 435 } 436 } 437 438 static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id) 439 { 440 switch (func_id) { 441 case BPF_FUNC_perf_event_output: 442 return &bpf_perf_event_output_proto; 443 case BPF_FUNC_get_stackid: 444 return &bpf_get_stackid_proto; 445 default: 446 return tracing_func_proto(func_id); 447 } 448 } 449 450 /* bpf+kprobe programs can access fields of 'struct pt_regs' */ 451 static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type, 452 enum bpf_reg_type *reg_type) 453 { 454 if (off < 0 || off >= sizeof(struct pt_regs)) 455 return false; 456 if (type != BPF_READ) 457 return false; 458 if (off % size != 0) 459 return false; 460 return true; 461 } 462 463 static const struct bpf_verifier_ops kprobe_prog_ops = { 464 .get_func_proto = kprobe_prog_func_proto, 465 .is_valid_access = kprobe_prog_is_valid_access, 466 }; 467 468 static struct bpf_prog_type_list kprobe_tl = { 469 .ops = &kprobe_prog_ops, 470 .type = BPF_PROG_TYPE_KPROBE, 471 }; 472 473 BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map, 474 u64, flags, void *, data, u64, size) 475 { 476 struct pt_regs *regs = *(struct pt_regs **)tp_buff; 477 478 /* 479 * r1 points to perf tracepoint buffer where first 8 bytes are hidden 480 * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it 481 * from there and call the same bpf_perf_event_output() helper inline. 482 */ 483 return ____bpf_perf_event_output(regs, map, flags, data, size); 484 } 485 486 static const struct bpf_func_proto bpf_perf_event_output_proto_tp = { 487 .func = bpf_perf_event_output_tp, 488 .gpl_only = true, 489 .ret_type = RET_INTEGER, 490 .arg1_type = ARG_PTR_TO_CTX, 491 .arg2_type = ARG_CONST_MAP_PTR, 492 .arg3_type = ARG_ANYTHING, 493 .arg4_type = ARG_PTR_TO_STACK, 494 .arg5_type = ARG_CONST_STACK_SIZE, 495 }; 496 497 BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map, 498 u64, flags) 499 { 500 struct pt_regs *regs = *(struct pt_regs **)tp_buff; 501 502 /* 503 * Same comment as in bpf_perf_event_output_tp(), only that this time 504 * the other helper's function body cannot be inlined due to being 505 * external, thus we need to call raw helper function. 506 */ 507 return bpf_get_stackid((unsigned long) regs, (unsigned long) map, 508 flags, 0, 0); 509 } 510 511 static const struct bpf_func_proto bpf_get_stackid_proto_tp = { 512 .func = bpf_get_stackid_tp, 513 .gpl_only = true, 514 .ret_type = RET_INTEGER, 515 .arg1_type = ARG_PTR_TO_CTX, 516 .arg2_type = ARG_CONST_MAP_PTR, 517 .arg3_type = ARG_ANYTHING, 518 }; 519 520 static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id) 521 { 522 switch (func_id) { 523 case BPF_FUNC_perf_event_output: 524 return &bpf_perf_event_output_proto_tp; 525 case BPF_FUNC_get_stackid: 526 return &bpf_get_stackid_proto_tp; 527 default: 528 return tracing_func_proto(func_id); 529 } 530 } 531 532 static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type, 533 enum bpf_reg_type *reg_type) 534 { 535 if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE) 536 return false; 537 if (type != BPF_READ) 538 return false; 539 if (off % size != 0) 540 return false; 541 return true; 542 } 543 544 static const struct bpf_verifier_ops tracepoint_prog_ops = { 545 .get_func_proto = tp_prog_func_proto, 546 .is_valid_access = tp_prog_is_valid_access, 547 }; 548 549 static struct bpf_prog_type_list tracepoint_tl = { 550 .ops = &tracepoint_prog_ops, 551 .type = BPF_PROG_TYPE_TRACEPOINT, 552 }; 553 554 static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type, 555 enum bpf_reg_type *reg_type) 556 { 557 if (off < 0 || off >= sizeof(struct bpf_perf_event_data)) 558 return false; 559 if (type != BPF_READ) 560 return false; 561 if (off % size != 0) 562 return false; 563 if (off == offsetof(struct bpf_perf_event_data, sample_period)) { 564 if (size != sizeof(u64)) 565 return false; 566 } else { 567 if (size != sizeof(long)) 568 return false; 569 } 570 return true; 571 } 572 573 static u32 pe_prog_convert_ctx_access(enum bpf_access_type type, int dst_reg, 574 int src_reg, int ctx_off, 575 struct bpf_insn *insn_buf, 576 struct bpf_prog *prog) 577 { 578 struct bpf_insn *insn = insn_buf; 579 580 switch (ctx_off) { 581 case offsetof(struct bpf_perf_event_data, sample_period): 582 BUILD_BUG_ON(FIELD_SIZEOF(struct perf_sample_data, period) != sizeof(u64)); 583 584 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern, 585 data), dst_reg, src_reg, 586 offsetof(struct bpf_perf_event_data_kern, data)); 587 *insn++ = BPF_LDX_MEM(BPF_DW, dst_reg, dst_reg, 588 offsetof(struct perf_sample_data, period)); 589 break; 590 default: 591 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern, 592 regs), dst_reg, src_reg, 593 offsetof(struct bpf_perf_event_data_kern, regs)); 594 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), dst_reg, dst_reg, ctx_off); 595 break; 596 } 597 598 return insn - insn_buf; 599 } 600 601 static const struct bpf_verifier_ops perf_event_prog_ops = { 602 .get_func_proto = tp_prog_func_proto, 603 .is_valid_access = pe_prog_is_valid_access, 604 .convert_ctx_access = pe_prog_convert_ctx_access, 605 }; 606 607 static struct bpf_prog_type_list perf_event_tl = { 608 .ops = &perf_event_prog_ops, 609 .type = BPF_PROG_TYPE_PERF_EVENT, 610 }; 611 612 static int __init register_kprobe_prog_ops(void) 613 { 614 bpf_register_prog_type(&kprobe_tl); 615 bpf_register_prog_type(&tracepoint_tl); 616 bpf_register_prog_type(&perf_event_tl); 617 return 0; 618 } 619 late_initcall(register_kprobe_prog_ops); 620