kernel/bpf/task_iter.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2020 Facebook */
   3
   4 #include <linux/init.h>
   5 #include <linux/namei.h>
   6 #include <linux/pid_namespace.h>
   7 #include <linux/fs.h>
   8 #include <linux/fdtable.h>
   9 #include <linux/filter.h>
  10 #include <linux/btf_ids.h>
  11 #include "mmap_unlock_work.h"
  12
  13 static const char * const iter_task_type_names[] = {
  14         "ALL",
  15         "TID",
  16         "PID",
  17 };
  18
  19 struct bpf_iter_seq_task_common {
  20         struct pid_namespace *ns;
  21         enum bpf_iter_task_type type;
  22         u32 pid;
  23         u32 pid_visiting;
  24 };
  25
  26 struct bpf_iter_seq_task_info {
  27         /* The first field must be struct bpf_iter_seq_task_common.
  28          * this is assumed by {init, fini}_seq_pidns() callback functions.
  29          */
  30         struct bpf_iter_seq_task_common common;
  31         u32 tid;
  32 };
  33
  34 static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_common *common,
  35                                                    u32 *tid,
  36                                                    bool skip_if_dup_files)
  37 {
  38         struct task_struct *task, *next_task;
  39         struct pid *pid;
  40         u32 saved_tid;
  41
  42         if (!*tid) {
  43                 /* The first time, the iterator calls this function. */
  44                 pid = find_pid_ns(common->pid, common->ns);
  45                 if (!pid)
  46                         return NULL;
  47
  48                 task = get_pid_task(pid, PIDTYPE_TGID);
  49                 if (!task)
  50                         return NULL;
  51
  52                 *tid = common->pid;
  53                 common->pid_visiting = common->pid;
  54
  55                 return task;
  56         }
  57
  58         /* If the control returns to user space and comes back to the
  59          * kernel again, *tid and common->pid_visiting should be the
  60          * same for task_seq_start() to pick up the correct task.
  61          */
  62         if (*tid == common->pid_visiting) {
  63                 pid = find_pid_ns(common->pid_visiting, common->ns);
  64                 task = get_pid_task(pid, PIDTYPE_PID);
  65
  66                 return task;
  67         }
  68
  69         pid = find_pid_ns(common->pid_visiting, common->ns);
  70         if (!pid)
  71                 return NULL;
  72
  73         task = get_pid_task(pid, PIDTYPE_PID);
  74         if (!task)
  75                 return NULL;
  76
  77 retry:
  78         if (!pid_alive(task)) {
  79                 put_task_struct(task);
  80                 return NULL;
  81         }
  82
  83         next_task = next_thread(task);
  84         put_task_struct(task);
  85         if (!next_task)
  86                 return NULL;
  87
  88         saved_tid = *tid;
  89         *tid = __task_pid_nr_ns(next_task, PIDTYPE_PID, common->ns);
  90         if (!*tid || *tid == common->pid) {
  91                 /* Run out of tasks of a process.  The tasks of a
  92                  * thread_group are linked as circular linked list.
  93                  */
  94                 *tid = saved_tid;
  95                 return NULL;
  96         }
  97
  98         get_task_struct(next_task);
  99         common->pid_visiting = *tid;
 100
 101         if (skip_if_dup_files && task->files == task->group_leader->files) {
 102                 task = next_task;
 103                 goto retry;
 104         }
 105
 106         return next_task;
 107 }
 108
 109 static struct task_struct *task_seq_get_next(struct bpf_iter_seq_task_common *common,
 110                                              u32 *tid,
 111                                              bool skip_if_dup_files)
 112 {
 113         struct task_struct *task = NULL;
 114         struct pid *pid;
 115
 116         if (common->type == BPF_TASK_ITER_TID) {
 117                 if (*tid && *tid != common->pid)
 118                         return NULL;
 119                 rcu_read_lock();
 120                 pid = find_pid_ns(common->pid, common->ns);
 121                 if (pid) {
 122                         task = get_pid_task(pid, PIDTYPE_TGID);
 123                         *tid = common->pid;
 124                 }
 125                 rcu_read_unlock();
 126
 127                 return task;
 128         }
 129
 130         if (common->type == BPF_TASK_ITER_TGID) {
 131                 rcu_read_lock();
 132                 task = task_group_seq_get_next(common, tid, skip_if_dup_files);
 133                 rcu_read_unlock();
 134
 135                 return task;
 136         }
 137
 138         rcu_read_lock();
 139 retry:
 140         pid = find_ge_pid(*tid, common->ns);
 141         if (pid) {
 142                 *tid = pid_nr_ns(pid, common->ns);
 143                 task = get_pid_task(pid, PIDTYPE_PID);
 144                 if (!task) {
 145                         ++*tid;
 146                         goto retry;
 147                 } else if (skip_if_dup_files && !thread_group_leader(task) &&
 148                            task->files == task->group_leader->files) {
 149                         put_task_struct(task);
 150                         task = NULL;
 151                         ++*tid;
 152                         goto retry;
 153                 }
 154         }
 155         rcu_read_unlock();
 156
 157         return task;
 158 }
 159
 160 static void *task_seq_start(struct seq_file *seq, loff_t *pos)
 161 {
 162         struct bpf_iter_seq_task_info *info = seq->private;
 163         struct task_struct *task;
 164
 165         task = task_seq_get_next(&info->common, &info->tid, false);
 166         if (!task)
 167                 return NULL;
 168
 169         if (*pos == 0)
 170                 ++*pos;
 171         return task;
 172 }
 173
 174 static void *task_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 175 {
 176         struct bpf_iter_seq_task_info *info = seq->private;
 177         struct task_struct *task;
 178
 179         ++*pos;
 180         ++info->tid;
 181         put_task_struct((struct task_struct *)v);
 182         task = task_seq_get_next(&info->common, &info->tid, false);
 183         if (!task)
 184                 return NULL;
 185
 186         return task;
 187 }
 188
 189 struct bpf_iter__task {
 190         __bpf_md_ptr(struct bpf_iter_meta *, meta);
 191         __bpf_md_ptr(struct task_struct *, task);
 192 };
 193
 194 DEFINE_BPF_ITER_FUNC(task, struct bpf_iter_meta *meta, struct task_struct *task)
 195
 196 static int __task_seq_show(struct seq_file *seq, struct task_struct *task,
 197                            bool in_stop)
 198 {
 199         struct bpf_iter_meta meta;
 200         struct bpf_iter__task ctx;
 201         struct bpf_prog *prog;
 202
 203         meta.seq = seq;
 204         prog = bpf_iter_get_info(&meta, in_stop);
 205         if (!prog)
 206                 return 0;
 207
 208         ctx.meta = &meta;
 209         ctx.task = task;
 210         return bpf_iter_run_prog(prog, &ctx);
 211 }
 212
 213 static int task_seq_show(struct seq_file *seq, void *v)
 214 {
 215         return __task_seq_show(seq, v, false);
 216 }
 217
 218 static void task_seq_stop(struct seq_file *seq, void *v)
 219 {
 220         if (!v)
 221                 (void)__task_seq_show(seq, v, true);
 222         else
 223                 put_task_struct((struct task_struct *)v);
 224 }
 225
 226 static int bpf_iter_attach_task(struct bpf_prog *prog,
 227                                 union bpf_iter_link_info *linfo,
 228                                 struct bpf_iter_aux_info *aux)
 229 {
 230         unsigned int flags;
 231         struct pid *pid;
 232         pid_t tgid;
 233
 234         if ((!!linfo->task.tid + !!linfo->task.pid + !!linfo->task.pid_fd) > 1)
 235                 return -EINVAL;
 236
 237         aux->task.type = BPF_TASK_ITER_ALL;
 238         if (linfo->task.tid != 0) {
 239                 aux->task.type = BPF_TASK_ITER_TID;
 240                 aux->task.pid = linfo->task.tid;
 241         }
 242         if (linfo->task.pid != 0) {
 243                 aux->task.type = BPF_TASK_ITER_TGID;
 244                 aux->task.pid = linfo->task.pid;
 245         }
 246         if (linfo->task.pid_fd != 0) {
 247                 aux->task.type = BPF_TASK_ITER_TGID;
 248
 249                 pid = pidfd_get_pid(linfo->task.pid_fd, &flags);
 250                 if (IS_ERR(pid))
 251                         return PTR_ERR(pid);
 252
 253                 tgid = pid_nr_ns(pid, task_active_pid_ns(current));
 254                 aux->task.pid = tgid;
 255                 put_pid(pid);
 256         }
 257
 258         return 0;
 259 }
 260
 261 static const struct seq_operations task_seq_ops = {
 262         .start  = task_seq_start,
 263         .next   = task_seq_next,
 264         .stop   = task_seq_stop,
 265         .show   = task_seq_show,
 266 };
 267
 268 struct bpf_iter_seq_task_file_info {
 269         /* The first field must be struct bpf_iter_seq_task_common.
 270          * this is assumed by {init, fini}_seq_pidns() callback functions.
 271          */
 272         struct bpf_iter_seq_task_common common;
 273         struct task_struct *task;
 274         u32 tid;
 275         u32 fd;
 276 };
 277
 278 static struct file *
 279 task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
 280 {
 281         u32 saved_tid = info->tid;
 282         struct task_struct *curr_task;
 283         unsigned int curr_fd = info->fd;
 284
 285         /* If this function returns a non-NULL file object,
 286          * it held a reference to the task/file.
 287          * Otherwise, it does not hold any reference.
 288          */
 289 again:
 290         if (info->task) {
 291                 curr_task = info->task;
 292                 curr_fd = info->fd;
 293         } else {
 294                 curr_task = task_seq_get_next(&info->common, &info->tid, true);
 295                 if (!curr_task) {
 296                         info->task = NULL;
 297                         return NULL;
 298                 }
 299
 300                 /* set info->task */
 301                 info->task = curr_task;
 302                 if (saved_tid == info->tid)
 303                         curr_fd = info->fd;
 304                 else
 305                         curr_fd = 0;
 306         }
 307
 308         rcu_read_lock();
 309         for (;; curr_fd++) {
 310                 struct file *f;
 311                 f = task_lookup_next_fdget_rcu(curr_task, &curr_fd);
 312                 if (!f)
 313                         break;
 314
 315                 /* set info->fd */
 316                 info->fd = curr_fd;
 317                 rcu_read_unlock();
 318                 return f;
 319         }
 320
 321         /* the current task is done, go to the next task */
 322         rcu_read_unlock();
 323         put_task_struct(curr_task);
 324
 325         if (info->common.type == BPF_TASK_ITER_TID) {
 326                 info->task = NULL;
 327                 return NULL;
 328         }
 329
 330         info->task = NULL;
 331         info->fd = 0;
 332         saved_tid = ++(info->tid);
 333         goto again;
 334 }
 335
 336 static void *task_file_seq_start(struct seq_file *seq, loff_t *pos)
 337 {
 338         struct bpf_iter_seq_task_file_info *info = seq->private;
 339         struct file *file;
 340
 341         info->task = NULL;
 342         file = task_file_seq_get_next(info);
 343         if (file && *pos == 0)
 344                 ++*pos;
 345
 346         return file;
 347 }
 348
 349 static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 350 {
 351         struct bpf_iter_seq_task_file_info *info = seq->private;
 352
 353         ++*pos;
 354         ++info->fd;
 355         fput((struct file *)v);
 356         return task_file_seq_get_next(info);
 357 }
 358
 359 struct bpf_iter__task_file {
 360         __bpf_md_ptr(struct bpf_iter_meta *, meta);
 361         __bpf_md_ptr(struct task_struct *, task);
 362         u32 fd __aligned(8);
 363         __bpf_md_ptr(struct file *, file);
 364 };
 365
 366 DEFINE_BPF_ITER_FUNC(task_file, struct bpf_iter_meta *meta,
 367                      struct task_struct *task, u32 fd,
 368                      struct file *file)
 369
 370 static int __task_file_seq_show(struct seq_file *seq, struct file *file,
 371                                 bool in_stop)
 372 {
 373         struct bpf_iter_seq_task_file_info *info = seq->private;
 374         struct bpf_iter__task_file ctx;
 375         struct bpf_iter_meta meta;
 376         struct bpf_prog *prog;
 377
 378         meta.seq = seq;
 379         prog = bpf_iter_get_info(&meta, in_stop);
 380         if (!prog)
 381                 return 0;
 382
 383         ctx.meta = &meta;
 384         ctx.task = info->task;
 385         ctx.fd = info->fd;
 386         ctx.file = file;
 387         return bpf_iter_run_prog(prog, &ctx);
 388 }
 389
 390 static int task_file_seq_show(struct seq_file *seq, void *v)
 391 {
 392         return __task_file_seq_show(seq, v, false);
 393 }
 394
 395 static void task_file_seq_stop(struct seq_file *seq, void *v)
 396 {
 397         struct bpf_iter_seq_task_file_info *info = seq->private;
 398
 399         if (!v) {
 400                 (void)__task_file_seq_show(seq, v, true);
 401         } else {
 402                 fput((struct file *)v);
 403                 put_task_struct(info->task);
 404                 info->task = NULL;
 405         }
 406 }
 407
 408 static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux)
 409 {
 410         struct bpf_iter_seq_task_common *common = priv_data;
 411
 412         common->ns = get_pid_ns(task_active_pid_ns(current));
 413         common->type = aux->task.type;
 414         common->pid = aux->task.pid;
 415
 416         return 0;
 417 }
 418
 419 static void fini_seq_pidns(void *priv_data)
 420 {
 421         struct bpf_iter_seq_task_common *common = priv_data;
 422
 423         put_pid_ns(common->ns);
 424 }
 425
 426 static const struct seq_operations task_file_seq_ops = {
 427         .start  = task_file_seq_start,
 428         .next   = task_file_seq_next,
 429         .stop   = task_file_seq_stop,
 430         .show   = task_file_seq_show,
 431 };
 432
 433 struct bpf_iter_seq_task_vma_info {
 434         /* The first field must be struct bpf_iter_seq_task_common.
 435          * this is assumed by {init, fini}_seq_pidns() callback functions.
 436          */
 437         struct bpf_iter_seq_task_common common;
 438         struct task_struct *task;
 439         struct mm_struct *mm;
 440         struct vm_area_struct *vma;
 441         u32 tid;
 442         unsigned long prev_vm_start;
 443         unsigned long prev_vm_end;
 444 };
 445
 446 enum bpf_task_vma_iter_find_op {
 447         task_vma_iter_first_vma,   /* use find_vma() with addr 0 */
 448         task_vma_iter_next_vma,    /* use vma_next() with curr_vma */
 449         task_vma_iter_find_vma,    /* use find_vma() to find next vma */
 450 };
 451
 452 static struct vm_area_struct *
 453 task_vma_seq_get_next(struct bpf_iter_seq_task_vma_info *info)
 454 {
 455         enum bpf_task_vma_iter_find_op op;
 456         struct vm_area_struct *curr_vma;
 457         struct task_struct *curr_task;
 458         struct mm_struct *curr_mm;
 459         u32 saved_tid = info->tid;
 460
 461         /* If this function returns a non-NULL vma, it holds a reference to
 462          * the task_struct, holds a refcount on mm->mm_users, and holds
 463          * read lock on vma->mm->mmap_lock.
 464          * If this function returns NULL, it does not hold any reference or
 465          * lock.
 466          */
 467         if (info->task) {
 468                 curr_task = info->task;
 469                 curr_vma = info->vma;
 470                 curr_mm = info->mm;
 471                 /* In case of lock contention, drop mmap_lock to unblock
 472                  * the writer.
 473                  *
 474                  * After relock, call find(mm, prev_vm_end - 1) to find
 475                  * new vma to process.
 476                  *
 477                  *   +------+------+-----------+
 478                  *   | VMA1 | VMA2 | VMA3      |
 479                  *   +------+------+-----------+
 480                  *   |      |      |           |
 481                  *  4k     8k     16k         400k
 482                  *
 483                  * For example, curr_vma == VMA2. Before unlock, we set
 484                  *
 485                  *    prev_vm_start = 8k
 486                  *    prev_vm_end   = 16k
 487                  *
 488                  * There are a few cases:
 489                  *
 490                  * 1) VMA2 is freed, but VMA3 exists.
 491                  *
 492                  *    find_vma() will return VMA3, just process VMA3.
 493                  *
 494                  * 2) VMA2 still exists.
 495                  *
 496                  *    find_vma() will return VMA2, process VMA2->next.
 497                  *
 498                  * 3) no more vma in this mm.
 499                  *
 500                  *    Process the next task.
 501                  *
 502                  * 4) find_vma() returns a different vma, VMA2'.
 503                  *
 504                  *    4.1) If VMA2 covers same range as VMA2', skip VMA2',
 505                  *         because we already covered the range;
 506                  *    4.2) VMA2 and VMA2' covers different ranges, process
 507                  *         VMA2'.
 508                  */
 509                 if (mmap_lock_is_contended(curr_mm)) {
 510                         info->prev_vm_start = curr_vma->vm_start;
 511                         info->prev_vm_end = curr_vma->vm_end;
 512                         op = task_vma_iter_find_vma;
 513                         mmap_read_unlock(curr_mm);
 514                         if (mmap_read_lock_killable(curr_mm)) {
 515                                 mmput(curr_mm);
 516                                 goto finish;
 517                         }
 518                 } else {
 519                         op = task_vma_iter_next_vma;
 520                 }
 521         } else {
 522 again:
 523                 curr_task = task_seq_get_next(&info->common, &info->tid, true);
 524                 if (!curr_task) {
 525                         info->tid++;
 526                         goto finish;
 527                 }
 528
 529                 if (saved_tid != info->tid) {
 530                         /* new task, process the first vma */
 531                         op = task_vma_iter_first_vma;
 532                 } else {
 533                         /* Found the same tid, which means the user space
 534                          * finished data in previous buffer and read more.
 535                          * We dropped mmap_lock before returning to user
 536                          * space, so it is necessary to use find_vma() to
 537                          * find the next vma to process.
 538                          */
 539                         op = task_vma_iter_find_vma;
 540                 }
 541
 542                 curr_mm = get_task_mm(curr_task);
 543                 if (!curr_mm)
 544                         goto next_task;
 545
 546                 if (mmap_read_lock_killable(curr_mm)) {
 547                         mmput(curr_mm);
 548                         goto finish;
 549                 }
 550         }
 551
 552         switch (op) {
 553         case task_vma_iter_first_vma:
 554                 curr_vma = find_vma(curr_mm, 0);
 555                 break;
 556         case task_vma_iter_next_vma:
 557                 curr_vma = find_vma(curr_mm, curr_vma->vm_end);
 558                 break;
 559         case task_vma_iter_find_vma:
 560                 /* We dropped mmap_lock so it is necessary to use find_vma
 561                  * to find the next vma. This is similar to the  mechanism
 562                  * in show_smaps_rollup().
 563                  */
 564                 curr_vma = find_vma(curr_mm, info->prev_vm_end - 1);
 565                 /* case 1) and 4.2) above just use curr_vma */
 566
 567                 /* check for case 2) or case 4.1) above */
 568                 if (curr_vma &&
 569                     curr_vma->vm_start == info->prev_vm_start &&
 570                     curr_vma->vm_end == info->prev_vm_end)
 571                         curr_vma = find_vma(curr_mm, curr_vma->vm_end);
 572                 break;
 573         }
 574         if (!curr_vma) {
 575                 /* case 3) above, or case 2) 4.1) with vma->next == NULL */
 576                 mmap_read_unlock(curr_mm);
 577                 mmput(curr_mm);
 578                 goto next_task;
 579         }
 580         info->task = curr_task;
 581         info->vma = curr_vma;
 582         info->mm = curr_mm;
 583         return curr_vma;
 584
 585 next_task:
 586         if (info->common.type == BPF_TASK_ITER_TID)
 587                 goto finish;
 588
 589         put_task_struct(curr_task);
 590         info->task = NULL;
 591         info->mm = NULL;
 592         info->tid++;
 593         goto again;
 594
 595 finish:
 596         if (curr_task)
 597                 put_task_struct(curr_task);
 598         info->task = NULL;
 599         info->vma = NULL;
 600         info->mm = NULL;
 601         return NULL;
 602 }
 603
 604 static void *task_vma_seq_start(struct seq_file *seq, loff_t *pos)
 605 {
 606         struct bpf_iter_seq_task_vma_info *info = seq->private;
 607         struct vm_area_struct *vma;
 608
 609         vma = task_vma_seq_get_next(info);
 610         if (vma && *pos == 0)
 611                 ++*pos;
 612
 613         return vma;
 614 }
 615
 616 static void *task_vma_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 617 {
 618         struct bpf_iter_seq_task_vma_info *info = seq->private;
 619
 620         ++*pos;
 621         return task_vma_seq_get_next(info);
 622 }
 623
 624 struct bpf_iter__task_vma {
 625         __bpf_md_ptr(struct bpf_iter_meta *, meta);
 626         __bpf_md_ptr(struct task_struct *, task);
 627         __bpf_md_ptr(struct vm_area_struct *, vma);
 628 };
 629
 630 DEFINE_BPF_ITER_FUNC(task_vma, struct bpf_iter_meta *meta,
 631                      struct task_struct *task, struct vm_area_struct *vma)
 632
 633 static int __task_vma_seq_show(struct seq_file *seq, bool in_stop)
 634 {
 635         struct bpf_iter_seq_task_vma_info *info = seq->private;
 636         struct bpf_iter__task_vma ctx;
 637         struct bpf_iter_meta meta;
 638         struct bpf_prog *prog;
 639
 640         meta.seq = seq;
 641         prog = bpf_iter_get_info(&meta, in_stop);
 642         if (!prog)
 643                 return 0;
 644
 645         ctx.meta = &meta;
 646         ctx.task = info->task;
 647         ctx.vma = info->vma;
 648         return bpf_iter_run_prog(prog, &ctx);
 649 }
 650
 651 static int task_vma_seq_show(struct seq_file *seq, void *v)
 652 {
 653         return __task_vma_seq_show(seq, false);
 654 }
 655
 656 static void task_vma_seq_stop(struct seq_file *seq, void *v)
 657 {
 658         struct bpf_iter_seq_task_vma_info *info = seq->private;
 659
 660         if (!v) {
 661                 (void)__task_vma_seq_show(seq, true);
 662         } else {
 663                 /* info->vma has not been seen by the BPF program. If the
 664                  * user space reads more, task_vma_seq_get_next should
 665                  * return this vma again. Set prev_vm_start to ~0UL,
 666                  * so that we don't skip the vma returned by the next
 667                  * find_vma() (case task_vma_iter_find_vma in
 668                  * task_vma_seq_get_next()).
 669                  */
 670                 info->prev_vm_start = ~0UL;
 671                 info->prev_vm_end = info->vma->vm_end;
 672                 mmap_read_unlock(info->mm);
 673                 mmput(info->mm);
 674                 info->mm = NULL;
 675                 put_task_struct(info->task);
 676                 info->task = NULL;
 677         }
 678 }
 679
 680 static const struct seq_operations task_vma_seq_ops = {
 681         .start  = task_vma_seq_start,
 682         .next   = task_vma_seq_next,
 683         .stop   = task_vma_seq_stop,
 684         .show   = task_vma_seq_show,
 685 };
 686
 687 static const struct bpf_iter_seq_info task_seq_info = {
 688         .seq_ops                = &task_seq_ops,
 689         .init_seq_private       = init_seq_pidns,
 690         .fini_seq_private       = fini_seq_pidns,
 691         .seq_priv_size          = sizeof(struct bpf_iter_seq_task_info),
 692 };
 693
 694 static int bpf_iter_fill_link_info(const struct bpf_iter_aux_info *aux, struct bpf_link_info *info)
 695 {
 696         switch (aux->task.type) {
 697         case BPF_TASK_ITER_TID:
 698                 info->iter.task.tid = aux->task.pid;
 699                 break;
 700         case BPF_TASK_ITER_TGID:
 701                 info->iter.task.pid = aux->task.pid;
 702                 break;
 703         default:
 704                 break;
 705         }
 706         return 0;
 707 }
 708
 709 static void bpf_iter_task_show_fdinfo(const struct bpf_iter_aux_info *aux, struct seq_file *seq)
 710 {
 711         seq_printf(seq, "task_type:\t%s\n", iter_task_type_names[aux->task.type]);
 712         if (aux->task.type == BPF_TASK_ITER_TID)
 713                 seq_printf(seq, "tid:\t%u\n", aux->task.pid);
 714         else if (aux->task.type == BPF_TASK_ITER_TGID)
 715                 seq_printf(seq, "pid:\t%u\n", aux->task.pid);
 716 }
 717
 718 static struct bpf_iter_reg task_reg_info = {
 719         .target                 = "task",
 720         .attach_target          = bpf_iter_attach_task,
 721         .feature                = BPF_ITER_RESCHED,
 722         .ctx_arg_info_size      = 1,
 723         .ctx_arg_info           = {
 724                 { offsetof(struct bpf_iter__task, task),
 725                   PTR_TO_BTF_ID_OR_NULL },
 726         },
 727         .seq_info               = &task_seq_info,
 728         .fill_link_info         = bpf_iter_fill_link_info,
 729         .show_fdinfo            = bpf_iter_task_show_fdinfo,
 730 };
 731
 732 static const struct bpf_iter_seq_info task_file_seq_info = {
 733         .seq_ops                = &task_file_seq_ops,
 734         .init_seq_private       = init_seq_pidns,
 735         .fini_seq_private       = fini_seq_pidns,
 736         .seq_priv_size          = sizeof(struct bpf_iter_seq_task_file_info),
 737 };
 738
 739 static struct bpf_iter_reg task_file_reg_info = {
 740         .target                 = "task_file",
 741         .attach_target          = bpf_iter_attach_task,
 742         .feature                = BPF_ITER_RESCHED,
 743         .ctx_arg_info_size      = 2,
 744         .ctx_arg_info           = {
 745                 { offsetof(struct bpf_iter__task_file, task),
 746                   PTR_TO_BTF_ID_OR_NULL },
 747                 { offsetof(struct bpf_iter__task_file, file),
 748                   PTR_TO_BTF_ID_OR_NULL },
 749         },
 750         .seq_info               = &task_file_seq_info,
 751         .fill_link_info         = bpf_iter_fill_link_info,
 752         .show_fdinfo            = bpf_iter_task_show_fdinfo,
 753 };
 754
 755 static const struct bpf_iter_seq_info task_vma_seq_info = {
 756         .seq_ops                = &task_vma_seq_ops,
 757         .init_seq_private       = init_seq_pidns,
 758         .fini_seq_private       = fini_seq_pidns,
 759         .seq_priv_size          = sizeof(struct bpf_iter_seq_task_vma_info),
 760 };
 761
 762 static struct bpf_iter_reg task_vma_reg_info = {
 763         .target                 = "task_vma",
 764         .attach_target          = bpf_iter_attach_task,
 765         .feature                = BPF_ITER_RESCHED,
 766         .ctx_arg_info_size      = 2,
 767         .ctx_arg_info           = {
 768                 { offsetof(struct bpf_iter__task_vma, task),
 769                   PTR_TO_BTF_ID_OR_NULL },
 770                 { offsetof(struct bpf_iter__task_vma, vma),
 771                   PTR_TO_BTF_ID_OR_NULL },
 772         },
 773         .seq_info               = &task_vma_seq_info,
 774         .fill_link_info         = bpf_iter_fill_link_info,
 775         .show_fdinfo            = bpf_iter_task_show_fdinfo,
 776 };
 777
 778 BPF_CALL_5(bpf_find_vma, struct task_struct *, task, u64, start,
 779            bpf_callback_t, callback_fn, void *, callback_ctx, u64, flags)
 780 {
 781         struct mmap_unlock_irq_work *work = NULL;
 782         struct vm_area_struct *vma;
 783         bool irq_work_busy = false;
 784         struct mm_struct *mm;
 785         int ret = -ENOENT;
 786
 787         if (flags)
 788                 return -EINVAL;
 789
 790         if (!task)
 791                 return -ENOENT;
 792
 793         mm = task->mm;
 794         if (!mm)
 795                 return -ENOENT;
 796
 797         irq_work_busy = bpf_mmap_unlock_get_irq_work(&work);
 798
 799         if (irq_work_busy || !mmap_read_trylock(mm))
 800                 return -EBUSY;
 801
 802         vma = find_vma(mm, start);
 803
 804         if (vma && vma->vm_start <= start && vma->vm_end > start) {
 805                 callback_fn((u64)(long)task, (u64)(long)vma,
 806                             (u64)(long)callback_ctx, 0, 0);
 807                 ret = 0;
 808         }
 809         bpf_mmap_unlock_mm(work, mm);
 810         return ret;
 811 }
 812
 813 const struct bpf_func_proto bpf_find_vma_proto = {
 814         .func           = bpf_find_vma,
 815         .ret_type       = RET_INTEGER,
 816         .arg1_type      = ARG_PTR_TO_BTF_ID,
 817         .arg1_btf_id    = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
 818         .arg2_type      = ARG_ANYTHING,
 819         .arg3_type      = ARG_PTR_TO_FUNC,
 820         .arg4_type      = ARG_PTR_TO_STACK_OR_NULL,
 821         .arg5_type      = ARG_ANYTHING,
 822 };
 823
 824 DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
 825
 826 static void do_mmap_read_unlock(struct irq_work *entry)
 827 {
 828         struct mmap_unlock_irq_work *work;
 829
 830         if (WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_RT)))
 831                 return;
 832
 833         work = container_of(entry, struct mmap_unlock_irq_work, irq_work);
 834         mmap_read_unlock_non_owner(work->mm);
 835 }
 836
 837 static int __init task_iter_init(void)
 838 {
 839         struct mmap_unlock_irq_work *work;
 840         int ret, cpu;
 841
 842         for_each_possible_cpu(cpu) {
 843                 work = per_cpu_ptr(&mmap_unlock_work, cpu);
 844                 init_irq_work(&work->irq_work, do_mmap_read_unlock);
 845         }
 846
 847         task_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
 848         ret = bpf_iter_reg_target(&task_reg_info);
 849         if (ret)
 850                 return ret;
 851
 852         task_file_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
 853         task_file_reg_info.ctx_arg_info[1].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_FILE];
 854         ret =  bpf_iter_reg_target(&task_file_reg_info);
 855         if (ret)
 856                 return ret;
 857
 858         task_vma_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
 859         task_vma_reg_info.ctx_arg_info[1].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA];
 860         return bpf_iter_reg_target(&task_vma_reg_info);
 861 }
 862 late_initcall(task_iter_init);