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 u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
  19
  20 /**
  21  * trace_call_bpf - invoke BPF program
  22  * @call: tracepoint event
  23  * @ctx: opaque context pointer
  24  *
  25  * kprobe handlers execute BPF programs via this helper.
  26  * Can be used from static tracepoints in the future.
  27  *
  28  * Return: BPF programs always return an integer which is interpreted by
  29  * kprobe handler as:
  30  * 0 - return from kprobe (event is filtered out)
  31  * 1 - store kprobe event into ring buffer
  32  * Other values are reserved and currently alias to 1
  33  */
  34 unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
  35 {
  36         unsigned int ret;
  37
  38         if (in_nmi()) /* not supported yet */
  39                 return 1;
  40
  41         preempt_disable();
  42
  43         if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
  44                 /*
  45                  * since some bpf program is already running on this cpu,
  46                  * don't call into another bpf program (same or different)
  47                  * and don't send kprobe event into ring-buffer,
  48                  * so return zero here
  49                  */
  50                 ret = 0;
  51                 goto out;
  52         }
  53
  54         /*
  55          * Instead of moving rcu_read_lock/rcu_dereference/rcu_read_unlock
  56          * to all call sites, we did a bpf_prog_array_valid() there to check
  57          * whether call->prog_array is empty or not, which is
  58          * a heurisitc to speed up execution.
  59          *
  60          * If bpf_prog_array_valid() fetched prog_array was
  61          * non-NULL, we go into trace_call_bpf() and do the actual
  62          * proper rcu_dereference() under RCU lock.
  63          * If it turns out that prog_array is NULL then, we bail out.
  64          * For the opposite, if the bpf_prog_array_valid() fetched pointer
  65          * was NULL, you'll skip the prog_array with the risk of missing
  66          * out of events when it was updated in between this and the
  67          * rcu_dereference() which is accepted risk.
  68          */
  69         ret = BPF_PROG_RUN_ARRAY_CHECK(call->prog_array, ctx, BPF_PROG_RUN);
  70
  71  out:
  72         __this_cpu_dec(bpf_prog_active);
  73         preempt_enable();
  74
  75         return ret;
  76 }
  77 EXPORT_SYMBOL_GPL(trace_call_bpf);
  78
  79 BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
  80 {
  81         int ret;
  82
  83         ret = probe_kernel_read(dst, unsafe_ptr, size);
  84         if (unlikely(ret < 0))
  85                 memset(dst, 0, size);
  86
  87         return ret;
  88 }
  89
  90 static const struct bpf_func_proto bpf_probe_read_proto = {
  91         .func           = bpf_probe_read,
  92         .gpl_only       = true,
  93         .ret_type       = RET_INTEGER,
  94         .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
  95         .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
  96         .arg3_type      = ARG_ANYTHING,
  97 };
  98
  99 BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src,
 100            u32, size)
 101 {
 102         /*
 103          * Ensure we're in user context which is safe for the helper to
 104          * run. This helper has no business in a kthread.
 105          *
 106          * access_ok() should prevent writing to non-user memory, but in
 107          * some situations (nommu, temporary switch, etc) access_ok() does
 108          * not provide enough validation, hence the check on KERNEL_DS.
 109          */
 110
 111         if (unlikely(in_interrupt() ||
 112                      current->flags & (PF_KTHREAD | PF_EXITING)))
 113                 return -EPERM;
 114         if (unlikely(uaccess_kernel()))
 115                 return -EPERM;
 116         if (!access_ok(VERIFY_WRITE, unsafe_ptr, size))
 117                 return -EPERM;
 118
 119         return probe_kernel_write(unsafe_ptr, src, size);
 120 }
 121
 122 static const struct bpf_func_proto bpf_probe_write_user_proto = {
 123         .func           = bpf_probe_write_user,
 124         .gpl_only       = true,
 125         .ret_type       = RET_INTEGER,
 126         .arg1_type      = ARG_ANYTHING,
 127         .arg2_type      = ARG_PTR_TO_MEM,
 128         .arg3_type      = ARG_CONST_SIZE,
 129 };
 130
 131 static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
 132 {
 133         pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!",
 134                             current->comm, task_pid_nr(current));
 135
 136         return &bpf_probe_write_user_proto;
 137 }
 138
 139 /*
 140  * Only limited trace_printk() conversion specifiers allowed:
 141  * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %s
 142  */
 143 BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
 144            u64, arg2, u64, arg3)
 145 {
 146         bool str_seen = false;
 147         int mod[3] = {};
 148         int fmt_cnt = 0;
 149         u64 unsafe_addr;
 150         char buf[64];
 151         int i;
 152
 153         /*
 154          * bpf_check()->check_func_arg()->check_stack_boundary()
 155          * guarantees that fmt points to bpf program stack,
 156          * fmt_size bytes of it were initialized and fmt_size > 0
 157          */
 158         if (fmt[--fmt_size] != 0)
 159                 return -EINVAL;
 160
 161         /* check format string for allowed specifiers */
 162         for (i = 0; i < fmt_size; i++) {
 163                 if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i]))
 164                         return -EINVAL;
 165
 166                 if (fmt[i] != '%')
 167                         continue;
 168
 169                 if (fmt_cnt >= 3)
 170                         return -EINVAL;
 171
 172                 /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
 173                 i++;
 174                 if (fmt[i] == 'l') {
 175                         mod[fmt_cnt]++;
 176                         i++;
 177                 } else if (fmt[i] == 'p' || fmt[i] == 's') {
 178                         mod[fmt_cnt]++;
 179                         i++;
 180                         if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)
 181                                 return -EINVAL;
 182                         fmt_cnt++;
 183                         if (fmt[i - 1] == 's') {
 184                                 if (str_seen)
 185                                         /* allow only one '%s' per fmt string */
 186                                         return -EINVAL;
 187                                 str_seen = true;
 188
 189                                 switch (fmt_cnt) {
 190                                 case 1:
 191                                         unsafe_addr = arg1;
 192                                         arg1 = (long) buf;
 193                                         break;
 194                                 case 2:
 195                                         unsafe_addr = arg2;
 196                                         arg2 = (long) buf;
 197                                         break;
 198                                 case 3:
 199                                         unsafe_addr = arg3;
 200                                         arg3 = (long) buf;
 201                                         break;
 202                                 }
 203                                 buf[0] = 0;
 204                                 strncpy_from_unsafe(buf,
 205                                                     (void *) (long) unsafe_addr,
 206                                                     sizeof(buf));
 207                         }
 208                         continue;
 209                 }
 210
 211                 if (fmt[i] == 'l') {
 212                         mod[fmt_cnt]++;
 213                         i++;
 214                 }
 215
 216                 if (fmt[i] != 'i' && fmt[i] != 'd' &&
 217                     fmt[i] != 'u' && fmt[i] != 'x')
 218                         return -EINVAL;
 219                 fmt_cnt++;
 220         }
 221
 222 /* Horrid workaround for getting va_list handling working with different
 223  * argument type combinations generically for 32 and 64 bit archs.
 224  */
 225 #define __BPF_TP_EMIT() __BPF_ARG3_TP()
 226 #define __BPF_TP(...)                                                   \
 227         __trace_printk(1 /* Fake ip will not be printed. */,            \
 228                        fmt, ##__VA_ARGS__)
 229
 230 #define __BPF_ARG1_TP(...)                                              \
 231         ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64))        \
 232           ? __BPF_TP(arg1, ##__VA_ARGS__)                               \
 233           : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32))    \
 234               ? __BPF_TP((long)arg1, ##__VA_ARGS__)                     \
 235               : __BPF_TP((u32)arg1, ##__VA_ARGS__)))
 236
 237 #define __BPF_ARG2_TP(...)                                              \
 238         ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64))        \
 239           ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__)                          \
 240           : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32))    \
 241               ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__)                \
 242               : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__)))
 243
 244 #define __BPF_ARG3_TP(...)                                              \
 245         ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64))        \
 246           ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__)                          \
 247           : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32))    \
 248               ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__)                \
 249               : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__)))
 250
 251         return __BPF_TP_EMIT();
 252 }
 253
 254 static const struct bpf_func_proto bpf_trace_printk_proto = {
 255         .func           = bpf_trace_printk,
 256         .gpl_only       = true,
 257         .ret_type       = RET_INTEGER,
 258         .arg1_type      = ARG_PTR_TO_MEM,
 259         .arg2_type      = ARG_CONST_SIZE,
 260 };
 261
 262 const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
 263 {
 264         /*
 265          * this program might be calling bpf_trace_printk,
 266          * so allocate per-cpu printk buffers
 267          */
 268         trace_printk_init_buffers();
 269
 270         return &bpf_trace_printk_proto;
 271 }
 272
 273 static __always_inline int
 274 get_map_perf_counter(struct bpf_map *map, u64 flags,
 275                      u64 *value, u64 *enabled, u64 *running)
 276 {
 277         struct bpf_array *array = container_of(map, struct bpf_array, map);
 278         unsigned int cpu = smp_processor_id();
 279         u64 index = flags & BPF_F_INDEX_MASK;
 280         struct bpf_event_entry *ee;
 281
 282         if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
 283                 return -EINVAL;
 284         if (index == BPF_F_CURRENT_CPU)
 285                 index = cpu;
 286         if (unlikely(index >= array->map.max_entries))
 287                 return -E2BIG;
 288
 289         ee = READ_ONCE(array->ptrs[index]);
 290         if (!ee)
 291                 return -ENOENT;
 292
 293         return perf_event_read_local(ee->event, value, enabled, running);
 294 }
 295
 296 BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags)
 297 {
 298         u64 value = 0;
 299         int err;
 300
 301         err = get_map_perf_counter(map, flags, &value, NULL, NULL);
 302         /*
 303          * this api is ugly since we miss [-22..-2] range of valid
 304          * counter values, but that's uapi
 305          */
 306         if (err)
 307                 return err;
 308         return value;
 309 }
 310
 311 static const struct bpf_func_proto bpf_perf_event_read_proto = {
 312         .func           = bpf_perf_event_read,
 313         .gpl_only       = true,
 314         .ret_type       = RET_INTEGER,
 315         .arg1_type      = ARG_CONST_MAP_PTR,
 316         .arg2_type      = ARG_ANYTHING,
 317 };
 318
 319 BPF_CALL_4(bpf_perf_event_read_value, struct bpf_map *, map, u64, flags,
 320            struct bpf_perf_event_value *, buf, u32, size)
 321 {
 322         int err = -EINVAL;
 323
 324         if (unlikely(size != sizeof(struct bpf_perf_event_value)))
 325                 goto clear;
 326         err = get_map_perf_counter(map, flags, &buf->counter, &buf->enabled,
 327                                    &buf->running);
 328         if (unlikely(err))
 329                 goto clear;
 330         return 0;
 331 clear:
 332         memset(buf, 0, size);
 333         return err;
 334 }
 335
 336 static const struct bpf_func_proto bpf_perf_event_read_value_proto = {
 337         .func           = bpf_perf_event_read_value,
 338         .gpl_only       = true,
 339         .ret_type       = RET_INTEGER,
 340         .arg1_type      = ARG_CONST_MAP_PTR,
 341         .arg2_type      = ARG_ANYTHING,
 342         .arg3_type      = ARG_PTR_TO_UNINIT_MEM,
 343         .arg4_type      = ARG_CONST_SIZE,
 344 };
 345
 346 static DEFINE_PER_CPU(struct perf_sample_data, bpf_sd);
 347
 348 static __always_inline u64
 349 __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
 350                         u64 flags, struct perf_raw_record *raw)
 351 {
 352         struct bpf_array *array = container_of(map, struct bpf_array, map);
 353         struct perf_sample_data *sd = this_cpu_ptr(&bpf_sd);
 354         unsigned int cpu = smp_processor_id();
 355         u64 index = flags & BPF_F_INDEX_MASK;
 356         struct bpf_event_entry *ee;
 357         struct perf_event *event;
 358
 359         if (index == BPF_F_CURRENT_CPU)
 360                 index = cpu;
 361         if (unlikely(index >= array->map.max_entries))
 362                 return -E2BIG;
 363
 364         ee = READ_ONCE(array->ptrs[index]);
 365         if (!ee)
 366                 return -ENOENT;
 367
 368         event = ee->event;
 369         if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
 370                      event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
 371                 return -EINVAL;
 372
 373         if (unlikely(event->oncpu != cpu))
 374                 return -EOPNOTSUPP;
 375
 376         perf_sample_data_init(sd, 0, 0);
 377         sd->raw = raw;
 378         perf_event_output(event, sd, regs);
 379         return 0;
 380 }
 381
 382 BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
 383            u64, flags, void *, data, u64, size)
 384 {
 385         struct perf_raw_record raw = {
 386                 .frag = {
 387                         .size = size,
 388                         .data = data,
 389                 },
 390         };
 391
 392         if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
 393                 return -EINVAL;
 394
 395         return __bpf_perf_event_output(regs, map, flags, &raw);
 396 }
 397
 398 static const struct bpf_func_proto bpf_perf_event_output_proto = {
 399         .func           = bpf_perf_event_output,
 400         .gpl_only       = true,
 401         .ret_type       = RET_INTEGER,
 402         .arg1_type      = ARG_PTR_TO_CTX,
 403         .arg2_type      = ARG_CONST_MAP_PTR,
 404         .arg3_type      = ARG_ANYTHING,
 405         .arg4_type      = ARG_PTR_TO_MEM,
 406         .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
 407 };
 408
 409 static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
 410
 411 u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
 412                      void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
 413 {
 414         struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs);
 415         struct perf_raw_frag frag = {
 416                 .copy           = ctx_copy,
 417                 .size           = ctx_size,
 418                 .data           = ctx,
 419         };
 420         struct perf_raw_record raw = {
 421                 .frag = {
 422                         {
 423                                 .next   = ctx_size ? &frag : NULL,
 424                         },
 425                         .size   = meta_size,
 426                         .data   = meta,
 427                 },
 428         };
 429
 430         perf_fetch_caller_regs(regs);
 431
 432         return __bpf_perf_event_output(regs, map, flags, &raw);
 433 }
 434
 435 BPF_CALL_0(bpf_get_current_task)
 436 {
 437         return (long) current;
 438 }
 439
 440 static const struct bpf_func_proto bpf_get_current_task_proto = {
 441         .func           = bpf_get_current_task,
 442         .gpl_only       = true,
 443         .ret_type       = RET_INTEGER,
 444 };
 445
 446 BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
 447 {
 448         struct bpf_array *array = container_of(map, struct bpf_array, map);
 449         struct cgroup *cgrp;
 450
 451         if (unlikely(in_interrupt()))
 452                 return -EINVAL;
 453         if (unlikely(idx >= array->map.max_entries))
 454                 return -E2BIG;
 455
 456         cgrp = READ_ONCE(array->ptrs[idx]);
 457         if (unlikely(!cgrp))
 458                 return -EAGAIN;
 459
 460         return task_under_cgroup_hierarchy(current, cgrp);
 461 }
 462
 463 static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
 464         .func           = bpf_current_task_under_cgroup,
 465         .gpl_only       = false,
 466         .ret_type       = RET_INTEGER,
 467         .arg1_type      = ARG_CONST_MAP_PTR,
 468         .arg2_type      = ARG_ANYTHING,
 469 };
 470
 471 BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
 472            const void *, unsafe_ptr)
 473 {
 474         int ret;
 475
 476         /*
 477          * The strncpy_from_unsafe() call will likely not fill the entire
 478          * buffer, but that's okay in this circumstance as we're probing
 479          * arbitrary memory anyway similar to bpf_probe_read() and might
 480          * as well probe the stack. Thus, memory is explicitly cleared
 481          * only in error case, so that improper users ignoring return
 482          * code altogether don't copy garbage; otherwise length of string
 483          * is returned that can be used for bpf_perf_event_output() et al.
 484          */
 485         ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
 486         if (unlikely(ret < 0))
 487                 memset(dst, 0, size);
 488
 489         return ret;
 490 }
 491
 492 static const struct bpf_func_proto bpf_probe_read_str_proto = {
 493         .func           = bpf_probe_read_str,
 494         .gpl_only       = true,
 495         .ret_type       = RET_INTEGER,
 496         .arg1_type      = ARG_PTR_TO_UNINIT_MEM,
 497         .arg2_type      = ARG_CONST_SIZE_OR_ZERO,
 498         .arg3_type      = ARG_ANYTHING,
 499 };
 500
 501 static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)
 502 {
 503         switch (func_id) {
 504         case BPF_FUNC_map_lookup_elem:
 505                 return &bpf_map_lookup_elem_proto;
 506         case BPF_FUNC_map_update_elem:
 507                 return &bpf_map_update_elem_proto;
 508         case BPF_FUNC_map_delete_elem:
 509                 return &bpf_map_delete_elem_proto;
 510         case BPF_FUNC_probe_read:
 511                 return &bpf_probe_read_proto;
 512         case BPF_FUNC_ktime_get_ns:
 513                 return &bpf_ktime_get_ns_proto;
 514         case BPF_FUNC_tail_call:
 515                 return &bpf_tail_call_proto;
 516         case BPF_FUNC_get_current_pid_tgid:
 517                 return &bpf_get_current_pid_tgid_proto;
 518         case BPF_FUNC_get_current_task:
 519                 return &bpf_get_current_task_proto;
 520         case BPF_FUNC_get_current_uid_gid:
 521                 return &bpf_get_current_uid_gid_proto;
 522         case BPF_FUNC_get_current_comm:
 523                 return &bpf_get_current_comm_proto;
 524         case BPF_FUNC_trace_printk:
 525                 return bpf_get_trace_printk_proto();
 526         case BPF_FUNC_get_smp_processor_id:
 527                 return &bpf_get_smp_processor_id_proto;
 528         case BPF_FUNC_get_numa_node_id:
 529                 return &bpf_get_numa_node_id_proto;
 530         case BPF_FUNC_perf_event_read:
 531                 return &bpf_perf_event_read_proto;
 532         case BPF_FUNC_probe_write_user:
 533                 return bpf_get_probe_write_proto();
 534         case BPF_FUNC_current_task_under_cgroup:
 535                 return &bpf_current_task_under_cgroup_proto;
 536         case BPF_FUNC_get_prandom_u32:
 537                 return &bpf_get_prandom_u32_proto;
 538         case BPF_FUNC_probe_read_str:
 539                 return &bpf_probe_read_str_proto;
 540         default:
 541                 return NULL;
 542         }
 543 }
 544
 545 static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
 546 {
 547         switch (func_id) {
 548         case BPF_FUNC_perf_event_output:
 549                 return &bpf_perf_event_output_proto;
 550         case BPF_FUNC_get_stackid:
 551                 return &bpf_get_stackid_proto;
 552         case BPF_FUNC_perf_event_read_value:
 553                 return &bpf_perf_event_read_value_proto;
 554         default:
 555                 return tracing_func_proto(func_id);
 556         }
 557 }
 558
 559 /* bpf+kprobe programs can access fields of 'struct pt_regs' */
 560 static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
 561                                         struct bpf_insn_access_aux *info)
 562 {
 563         if (off < 0 || off >= sizeof(struct pt_regs))
 564                 return false;
 565         if (type != BPF_READ)
 566                 return false;
 567         if (off % size != 0)
 568                 return false;
 569         /*
 570          * Assertion for 32 bit to make sure last 8 byte access
 571          * (BPF_DW) to the last 4 byte member is disallowed.
 572          */
 573         if (off + size > sizeof(struct pt_regs))
 574                 return false;
 575
 576         return true;
 577 }
 578
 579 const struct bpf_verifier_ops kprobe_verifier_ops = {
 580         .get_func_proto  = kprobe_prog_func_proto,
 581         .is_valid_access = kprobe_prog_is_valid_access,
 582 };
 583
 584 const struct bpf_prog_ops kprobe_prog_ops = {
 585 };
 586
 587 BPF_CALL_5(bpf_perf_event_output_tp, void *, tp_buff, struct bpf_map *, map,
 588            u64, flags, void *, data, u64, size)
 589 {
 590         struct pt_regs *regs = *(struct pt_regs **)tp_buff;
 591
 592         /*
 593          * r1 points to perf tracepoint buffer where first 8 bytes are hidden
 594          * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
 595          * from there and call the same bpf_perf_event_output() helper inline.
 596          */
 597         return ____bpf_perf_event_output(regs, map, flags, data, size);
 598 }
 599
 600 static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
 601         .func           = bpf_perf_event_output_tp,
 602         .gpl_only       = true,
 603         .ret_type       = RET_INTEGER,
 604         .arg1_type      = ARG_PTR_TO_CTX,
 605         .arg2_type      = ARG_CONST_MAP_PTR,
 606         .arg3_type      = ARG_ANYTHING,
 607         .arg4_type      = ARG_PTR_TO_MEM,
 608         .arg5_type      = ARG_CONST_SIZE_OR_ZERO,
 609 };
 610
 611 BPF_CALL_3(bpf_get_stackid_tp, void *, tp_buff, struct bpf_map *, map,
 612            u64, flags)
 613 {
 614         struct pt_regs *regs = *(struct pt_regs **)tp_buff;
 615
 616         /*
 617          * Same comment as in bpf_perf_event_output_tp(), only that this time
 618          * the other helper's function body cannot be inlined due to being
 619          * external, thus we need to call raw helper function.
 620          */
 621         return bpf_get_stackid((unsigned long) regs, (unsigned long) map,
 622                                flags, 0, 0);
 623 }
 624
 625 static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
 626         .func           = bpf_get_stackid_tp,
 627         .gpl_only       = true,
 628         .ret_type       = RET_INTEGER,
 629         .arg1_type      = ARG_PTR_TO_CTX,
 630         .arg2_type      = ARG_CONST_MAP_PTR,
 631         .arg3_type      = ARG_ANYTHING,
 632 };
 633
 634 BPF_CALL_3(bpf_perf_prog_read_value_tp, struct bpf_perf_event_data_kern *, ctx,
 635            struct bpf_perf_event_value *, buf, u32, size)
 636 {
 637         int err = -EINVAL;
 638
 639         if (unlikely(size != sizeof(struct bpf_perf_event_value)))
 640                 goto clear;
 641         err = perf_event_read_local(ctx->event, &buf->counter, &buf->enabled,
 642                                     &buf->running);
 643         if (unlikely(err))
 644                 goto clear;
 645         return 0;
 646 clear:
 647         memset(buf, 0, size);
 648         return err;
 649 }
 650
 651 static const struct bpf_func_proto bpf_perf_prog_read_value_proto_tp = {
 652          .func           = bpf_perf_prog_read_value_tp,
 653          .gpl_only       = true,
 654          .ret_type       = RET_INTEGER,
 655          .arg1_type      = ARG_PTR_TO_CTX,
 656          .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
 657          .arg3_type      = ARG_CONST_SIZE,
 658 };
 659
 660 static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
 661 {
 662         switch (func_id) {
 663         case BPF_FUNC_perf_event_output:
 664                 return &bpf_perf_event_output_proto_tp;
 665         case BPF_FUNC_get_stackid:
 666                 return &bpf_get_stackid_proto_tp;
 667         case BPF_FUNC_perf_prog_read_value:
 668                 return &bpf_perf_prog_read_value_proto_tp;
 669         default:
 670                 return tracing_func_proto(func_id);
 671         }
 672 }
 673
 674 static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,
 675                                     struct bpf_insn_access_aux *info)
 676 {
 677         if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)
 678                 return false;
 679         if (type != BPF_READ)
 680                 return false;
 681         if (off % size != 0)
 682                 return false;
 683
 684         BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64));
 685         return true;
 686 }
 687
 688 const struct bpf_verifier_ops tracepoint_verifier_ops = {
 689         .get_func_proto  = tp_prog_func_proto,
 690         .is_valid_access = tp_prog_is_valid_access,
 691 };
 692
 693 const struct bpf_prog_ops tracepoint_prog_ops = {
 694 };
 695
 696 static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
 697                                     struct bpf_insn_access_aux *info)
 698 {
 699         const int size_sp = FIELD_SIZEOF(struct bpf_perf_event_data,
 700                                          sample_period);
 701
 702         if (off < 0 || off >= sizeof(struct bpf_perf_event_data))
 703                 return false;
 704         if (type != BPF_READ)
 705                 return false;
 706         if (off % size != 0)
 707                 return false;
 708
 709         switch (off) {
 710         case bpf_ctx_range(struct bpf_perf_event_data, sample_period):
 711                 bpf_ctx_record_field_size(info, size_sp);
 712                 if (!bpf_ctx_narrow_access_ok(off, size, size_sp))
 713                         return false;
 714                 break;
 715         default:
 716                 if (size != sizeof(long))
 717                         return false;
 718         }
 719
 720         return true;
 721 }
 722
 723 static u32 pe_prog_convert_ctx_access(enum bpf_access_type type,
 724                                       const struct bpf_insn *si,
 725                                       struct bpf_insn *insn_buf,
 726                                       struct bpf_prog *prog, u32 *target_size)
 727 {
 728         struct bpf_insn *insn = insn_buf;
 729
 730         switch (si->off) {
 731         case offsetof(struct bpf_perf_event_data, sample_period):
 732                 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
 733                                                        data), si->dst_reg, si->src_reg,
 734                                       offsetof(struct bpf_perf_event_data_kern, data));
 735                 *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,
 736                                       bpf_target_off(struct perf_sample_data, period, 8,
 737                                                      target_size));
 738                 break;
 739         default:
 740                 *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,
 741                                                        regs), si->dst_reg, si->src_reg,
 742                                       offsetof(struct bpf_perf_event_data_kern, regs));
 743                 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), si->dst_reg, si->dst_reg,
 744                                       si->off);
 745                 break;
 746         }
 747
 748         return insn - insn_buf;
 749 }
 750
 751 const struct bpf_verifier_ops perf_event_verifier_ops = {
 752         .get_func_proto         = tp_prog_func_proto,
 753         .is_valid_access        = pe_prog_is_valid_access,
 754         .convert_ctx_access     = pe_prog_convert_ctx_access,
 755 };
 756
 757 const struct bpf_prog_ops perf_event_prog_ops = {
 758 };
 759
 760 static DEFINE_MUTEX(bpf_event_mutex);
 761
 762 int perf_event_attach_bpf_prog(struct perf_event *event,
 763                                struct bpf_prog *prog)
 764 {
 765         struct bpf_prog_array __rcu *old_array;
 766         struct bpf_prog_array *new_array;
 767         int ret = -EEXIST;
 768
 769         mutex_lock(&bpf_event_mutex);
 770
 771         if (event->prog)
 772                 goto unlock;
 773
 774         old_array = event->tp_event->prog_array;
 775         ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
 776         if (ret < 0)
 777                 goto unlock;
 778
 779         /* set the new array to event->tp_event and set event->prog */
 780         event->prog = prog;
 781         rcu_assign_pointer(event->tp_event->prog_array, new_array);
 782         bpf_prog_array_free(old_array);
 783
 784 unlock:
 785         mutex_unlock(&bpf_event_mutex);
 786         return ret;
 787 }
 788
 789 void perf_event_detach_bpf_prog(struct perf_event *event)
 790 {
 791         struct bpf_prog_array __rcu *old_array;
 792         struct bpf_prog_array *new_array;
 793         int ret;
 794
 795         mutex_lock(&bpf_event_mutex);
 796
 797         if (!event->prog)
 798                 goto unlock;
 799
 800         old_array = event->tp_event->prog_array;
 801         ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
 802         if (ret < 0) {
 803                 bpf_prog_array_delete_safe(old_array, event->prog);
 804         } else {
 805                 rcu_assign_pointer(event->tp_event->prog_array, new_array);
 806                 bpf_prog_array_free(old_array);
 807         }
 808
 809         bpf_prog_put(event->prog);
 810         event->prog = NULL;
 811
 812 unlock:
 813         mutex_unlock(&bpf_event_mutex);
 814 }