kernel/trace/bpf_trace.c

   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_UNINIT_MEM,
  80         .arg2_type      = ARG_CONST_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(uaccess_kernel()))
 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_MEM,
 113         .arg3_type      = ARG_CONST_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  * Only limited trace_printk() conversion specifiers allowed:
 126  * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %s
 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] != 'i' && fmt[i] != 'd' &&
 202                     fmt[i] != 'u' && fmt[i] != 'x')
 203                         return -EINVAL;
 204                 fmt_cnt++;
 205         }
 206
 207 /* Horrid workaround for getting va_list handling working with different
 208  * argument type combinations generically for 32 and 64 bit archs.
 209  */
 210 #define __BPF_TP_EMIT() __BPF_ARG3_TP()
 211 #define __BPF_TP(...)                                                   \
 212         __trace_printk(1 /* Fake ip will not be printed. */,            \
 213                        fmt, ##__VA_ARGS__)
 214
 215 #define __BPF_ARG1_TP(...)                                              \
 216         ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64))        \
 217           ? __BPF_TP(arg1, ##__VA_ARGS__)                               \
 218           : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32))    \
 219               ? __BPF_TP((long)arg1, ##__VA_ARGS__)                     \
 220               : __BPF_TP((u32)arg1, ##__VA_ARGS__)))
 221
 222 #define __BPF_ARG2_TP(...)                                              \
 223         ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64))        \
 224           ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__)                          \
 225           : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32))    \
 226               ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__)                \
 227               : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__)))
 228
 229 #define __BPF_ARG3_TP(...)                                              \
 230         ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64))        \
 231           ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__)                          \
 232           : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32))    \
 233               ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__)                \
 234               : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__)))
 235
 236         return __BPF_TP_EMIT();
 237 }
 238
 239 static const struct bpf_func_proto bpf_trace_printk_proto = {
 240         .func           = bpf_trace_printk,
 241         .gpl_only       = true,
 242         .ret_type       = RET_INTEGER,
 243         .arg1_type      = ARG_PTR_TO_MEM,
 244         .arg2_type      = ARG_CONST_SIZE,
 245 };
 246
 247 const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
 248 {
 249         /*
 250          * this program might be calling bpf_trace_printk,
 251          * so allocate per-cpu printk buffers
 252          */
 253         trace_printk_init_buffers();
 254
 255         return &bpf_trace_printk_proto;
 256 }
 257
 258 BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags)
 259 {
 260         struct bpf_array *array = container_of(map, struct bpf_array, map);
 261         unsigned int cpu = smp_processor_id();
 262         u64 index = flags & BPF_F_INDEX_MASK;
 263         struct bpf_event_entry *ee;
 264         u64 value = 0;
 265         int err;
 266
 267         if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
 268                 return -EINVAL;
 269         if (index == BPF_F_CURRENT_CPU)
 270                 index = cpu;
 271         if (unlikely(index >= array->map.max_entries))
 272                 return -E2BIG;
 273
 274         ee = READ_ONCE(array->ptrs[index]);
 275         if (!ee)
 276                 return -ENOENT;
 277
 278         err = perf_event_read_local(ee->event, &value);
 279         /*
 280          * this api is ugly since we miss [-22..-2] range of valid
 281          * counter values, but that's uapi
 282          */
 283         if (err)
 284                 return err;
 285         return value;
 286 }
 287
 288 static const struct bpf_func_proto bpf_perf_event_read_proto = {
 289         .func           = bpf_perf_event_read,
 290         .gpl_only       = true,
 291         .ret_type       = RET_INTEGER,
 292         .arg1_type      = ARG_CONST_MAP_PTR,
 293         .arg2_type      = ARG_ANYTHING,
 294 };
 295
 296 static DEFINE_PER_CPU(struct perf_sample_data, bpf_sd);
 297
 298 static __always_inline u64
 299 __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
 300                         u64 flags, struct perf_raw_record *raw)
 301 {
 302         struct bpf_array *array = container_of(map, struct bpf_array, map);
 303         struct perf_sample_data *sd = this_cpu_ptr(&bpf_sd);
 304         unsigned int cpu = smp_processor_id();
 305         u64 index = flags & BPF_F_INDEX_MASK;
 306         struct bpf_event_entry *ee;
 307         struct perf_event *event;
 308
 309         if (index == BPF_F_CURRENT_CPU)
 310                 index = cpu;
 311         if (unlikely(index >= array->map.max_entries))
 312                 return -E2BIG;
 313
 314         ee = READ_ONCE(array->ptrs[index]);
 315         if (!ee)
 316                 return -ENOENT;
 317
 318         event = ee->event;
 319         if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
 320                      event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
 321                 return -EINVAL;
 322
 323         if (unlikely(event->oncpu != cpu))
 324                 return -EOPNOTSUPP;
 325
 326         perf_sample_data_init(sd, 0, 0);
 327         sd->raw = raw;
 328         perf_event_output(event, sd, regs);
 329         return 0;
 330 }
 331
 332 BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
 333            u64, flags, void *, data, u64, size)
 334 {
 335         struct perf_raw_record raw = {
 336                 .frag = {
 337                         .size = size,
 338                         .data = data,
 339                 },
 340         };
 341
 342         if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
 343                 return -EINVAL;
 344
 345         return __bpf_perf_event_output(regs, map, flags, &raw);
 346 }
 347
 348 static const struct bpf_func_proto bpf_perf_event_output_proto = {
 349         .func           = bpf_perf_event_output,
 350         .gpl_only       = true,
 351         .ret_type       = RET_INTEGER,
 352         .arg1_type      = ARG_PTR_TO_CTX,
 353         .arg2_type      = ARG_CONST_MAP_PTR,
 354         .arg3_type      = ARG_ANYTHING,
 355         .arg4_type      = ARG_PTR_TO_MEM,
 356         .arg5_type      = ARG_CONST_SIZE,
 357 };
 358
 359 static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
 360
 361 u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
 362                      void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
 363 {
 364         struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs);
 365         struct perf_raw_frag frag = {
 366                 .copy           = ctx_copy,
 367                 .size           = ctx_size,
 368                 .data           = ctx,
 369         };
 370         struct perf_raw_record raw = {
 371                 .frag = {
 372                         {
 373                                 .next   = ctx_size ? &frag : NULL,
 374                         },
 375                         .size   = meta_size,
 376                         .data   = meta,
 377                 },
 378         };
 379
 380         perf_fetch_caller_regs(regs);
 381
 382         return __bpf_perf_event_output(regs, map, flags, &raw);
 383 }
 384
 385 BPF_CALL_0(bpf_get_current_task)
 386 {
 387         return (long) current;
 388 }
 389
 390 static const struct bpf_func_proto bpf_get_current_task_proto = {
 391         .func           = bpf_get_current_task,
 392         .gpl_only       = true,
 393         .ret_type       = RET_INTEGER,
 394 };
 395
 396 BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
 397 {
 398         struct bpf_array *array = container_of(map, struct bpf_array, map);
 399         struct cgroup *cgrp;
 400
 401         if (unlikely(in_interrupt()))
 402                 return -EINVAL;
 403         if (unlikely(idx >= array->map.max_entries))
 404                 return -E2BIG;
 405
 406         cgrp = READ_ONCE(array->ptrs[idx]);
 407         if (unlikely(!cgrp))
 408                 return -EAGAIN;
 409
 410         return task_under_cgroup_hierarchy(current, cgrp);
 411 }
 412
 413 static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
 414         .func           = bpf_current_task_under_cgroup,
 415         .gpl_only       = false,
 416         .ret_type       = RET_INTEGER,
 417         .arg1_type      = ARG_CONST_MAP_PTR,
 418         .arg2_type      = ARG_ANYTHING,
 419 };
 420
 421 BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
 422            const void *, unsafe_ptr)
 423 {
 424         int ret;
 425
 426         /*
 427          * The strncpy_from_unsafe() call will likely not fill the entire
 428          * buffer, but that's okay in this circumstance as we're probing
 429          * arbitrary memory anyway similar to bpf_probe_read() and might
 430          * as well probe the stack. Thus, memory is explicitly cleared
 431          * only in error case, so that improper users ignoring return
 432          * code altogether don't copy garbage; otherwise length of string
 433          * is returned that can be used for bpf_perf_event_output() et al.
 434          */
 435         ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
 436         if (unlikely(ret < 0))
 437                 memset(dst, 0, size);
 438
 439         return ret;
 440 }
 441
 442 static const struct bpf_func_proto bpf_probe_read_str_proto = {
 443         .func           = bpf_probe_read_str,
 444         .gpl_only       = true,
 445         .ret_type       = RET_INTEGER,
 446         .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
 447         .arg2_type      = ARG_CONST_SIZE,
 448         .arg3_type      = ARG_ANYTHING,
 449 };
 450
 451 static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)
 452 {
 453         switch (func_id) {
 454         case BPF_FUNC_map_lookup_elem:
 455                 return &bpf_map_lookup_elem_proto;
 456         case BPF_FUNC_map_update_elem:
 457                 return &bpf_map_update_elem_proto;
 458         case BPF_FUNC_map_delete_elem:
 459                 return &bpf_map_delete_elem_proto;
 460         case BPF_FUNC_probe_read:
 461                 return &bpf_probe_read_proto;
 462         case BPF_FUNC_ktime_get_ns:
 463                 return &bpf_ktime_get_ns_proto;
 464         case BPF_FUNC_tail_call:
 465                 return &bpf_tail_call_proto;
 466         case BPF_FUNC_get_current_pid_tgid:
 467                 return &bpf_get_current_pid_tgid_proto;
 468         case BPF_FUNC_get_current_task:
 469                 return &bpf_get_current_task_proto;
 470         case BPF_FUNC_get_current_uid_gid:
 471                 return &bpf_get_current_uid_gid_proto;
 472         case BPF_FUNC_get_current_comm:
 473                 return &bpf_get_current_comm_proto;
 474         case BPF_FUNC_trace_printk:
 475                 return bpf_get_trace_printk_proto();
 476         case BPF_FUNC_get_smp_processor_id:
 477                 return &bpf_get_smp_processor_id_proto;
 478         case BPF_FUNC_get_numa_node_id:
 479                 return &bpf_get_numa_node_id_proto;
 480         case BPF_FUNC_perf_event_read:
 481                 return &bpf_perf_event_read_proto;
 482         case BPF_FUNC_probe_write_user:
 483                 return bpf_get_probe_write_proto();
 484         case BPF_FUNC_current_task_under_cgroup:
 485                 return &bpf_current_task_under_cgroup_proto;
 486         case BPF_FUNC_get_prandom_u32:
 487                 return &bpf_get_prandom_u32_proto;
 488         case BPF_FUNC_probe_read_str:
 489                 return &bpf_probe_read_str_proto;
 490         default:
 491                 return NULL;
 492         }
 493 }
 494
 495 static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
 496 {
 497         switch (func_id) {
 498         case BPF_FUNC_perf_event_output:
 499                 return &bpf_perf_event_output_proto;
 500         case BPF_FUNC_get_stackid:
 501                 return &bpf_get_stackid_proto;
 502         default:
 503                 return tracing_func_proto(func_id);
 504         }
 505 }
 506
 507 /* bpf+kprobe programs can access fields of 'struct pt_regs' */
 508 static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
 509                                         struct bpf_insn_access_aux *info)
 510 {
 511         if (off < 0 || off >= sizeof(struct pt_regs))
 512                 return false;
 513         if (type != BPF_READ)
 514                 return false;
 515         if (off % size != 0)
 516                 return false;
 517         /*
 518          * Assertion for 32 bit to make sure last 8 byte access
 519          * (BPF_DW) to the last 4 byte member is disallowed.
 520          */
 521         if (off + size > sizeof(struct pt_regs))
 522                 return false;
 523
 524         return true;
 525 }
 526
 527 const struct bpf_verifier_ops kprobe_prog_ops = {
 528         .get_func_proto  = kprobe_prog_func_proto,
 529         .is_valid_access = kprobe_prog_is_valid_access,
 530 };
 531
 532 BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map,
 533            u64, flags, void *, data, u64, size)
 534 {
 535         struct pt_regs *regs = *(struct pt_regs **)tp_buff;
 536
 537         /*
 538          * r1 points to perf tracepoint buffer where first 8 bytes are hidden
 539          * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
 540          * from there and call the same bpf_perf_event_output() helper inline.
 541          */
 542         return ____bpf_perf_event_output(regs, map, flags, data, size);
 543 }
 544
 545 static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
 546         .func           = bpf_perf_event_output_tp,
 547         .gpl_only       = true,
 548         .ret_type       = RET_INTEGER,
 549         .arg1_type      = ARG_PTR_TO_CTX,
 550         .arg2_type      = ARG_CONST_MAP_PTR,
 551         .arg3_type      = ARG_ANYTHING,
 552         .arg4_type      = ARG_PTR_TO_MEM,
 553         .arg5_type      = ARG_CONST_SIZE,
 554 };
 555
 556 BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map,
 557            u64, flags)
 558 {
 559         struct pt_regs *regs = *(struct pt_regs **)tp_buff;
 560
 561         /*
 562          * Same comment as in bpf_perf_event_output_tp(), only that this time
 563          * the other helper's function body cannot be inlined due to being
 564          * external, thus we need to call raw helper function.
 565          */
 566         return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
 567                                flags, 0, 0);
 568 }
 569
 570 static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
 571         .func           = bpf_get_stackid_tp,
 572         .gpl_only       = true,
 573         .ret_type       = RET_INTEGER,
 574         .arg1_type      = ARG_PTR_TO_CTX,
 575         .arg2_type      = ARG_CONST_MAP_PTR,
 576         .arg3_type      = ARG_ANYTHING,
 577 };
 578
 579 static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
 580 {
 581         switch (func_id) {
 582         case BPF_FUNC_perf_event_output:
 583                 return &bpf_perf_event_output_proto_tp;
 584         case BPF_FUNC_get_stackid:
 585                 return &bpf_get_stackid_proto_tp;
 586         default:
 587                 return tracing_func_proto(func_id);
 588         }
 589 }
 590
 591 static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,
 592                                     struct bpf_insn_access_aux *info)
 593 {
 594         if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)
 595                 return false;
 596         if (type != BPF_READ)
 597                 return false;
 598         if (off % size != 0)
 599                 return false;
 600
 601         BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64));
 602         return true;
 603 }
 604
 605 const struct bpf_verifier_ops tracepoint_prog_ops = {
 606         .get_func_proto  = tp_prog_func_proto,
 607         .is_valid_access = tp_prog_is_valid_access,
 608 };
 609
 610 static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
 611                                     struct bpf_insn_access_aux *info)
 612 {
 613         const int size_sp = FIELD_SIZEOF(struct bpf_perf_event_data,
 614                                          sample_period);
 615
 616         if (off < 0 || off >= sizeof(struct bpf_perf_event_data))
 617                 return false;
 618         if (type != BPF_READ)
 619                 return false;
 620         if (off % size != 0)
 621                 return false;
 622
 623         switch (off) {
 624         case bpf_ctx_range(struct bpf_perf_event_data, sample_period):
 625                 bpf_ctx_record_field_size(info, size_sp);
 626                 if (!bpf_ctx_narrow_access_ok(off, size, size_sp))
 627                         return false;
 628                 break;
 629         default:
 630                 if (size != sizeof(long))
 631                         return false;
 632         }
 633
 634         return true;
 635 }
 636
 637 static u32 pe_prog_convert_ctx_access(enum bpf_access_type type,
 638                                       const struct bpf_insn *si,
 639                                       struct bpf_insn *insn_buf,
 640                                       struct bpf_prog *prog, u32 *target_size)
 641 {
 642         struct bpf_insn *insn = insn_buf;
 643
 644         switch (si->off) {
 645         case offsetof(struct bpf_perf_event_data, sample_period):
 646                 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
 647                                                        data), si->dst_reg, si->src_reg,
 648                                       offsetof(struct bpf_perf_event_data_kern, data));
 649                 *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
 650                                       bpf_target_off(struct perf_sample_data, period, 8,
 651                                                      target_size));
 652                 break;
 653         default:
 654                 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
 655                                                        regs), si->dst_reg, si->src_reg,
 656                                       offsetof(struct bpf_perf_event_data_kern, regs));
 657                 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), si->dst_reg, si->dst_reg,
 658                                       si->off);
 659                 break;
 660         }
 661
 662         return insn - insn_buf;
 663 }
 664
 665 const struct bpf_verifier_ops perf_event_prog_ops = {
 666         .get_func_proto         = tp_prog_func_proto,
 667         .is_valid_access        = pe_prog_is_valid_access,
 668         .convert_ctx_access     = pe_prog_convert_ctx_access,
 669 };