linux/fs/proc/base.c
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   1/*
   2 *  linux/fs/proc/base.c
   3 *
   4 *  Copyright (C) 1991, 1992 Linus Torvalds
   5 *
   6 *  proc base directory handling functions
   7 *
   8 *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
   9 *  Instead of using magical inumbers to determine the kind of object
  10 *  we allocate and fill in-core inodes upon lookup. They don't even
  11 *  go into icache. We cache the reference to task_struct upon lookup too.
  12 *  Eventually it should become a filesystem in its own. We don't use the
  13 *  rest of procfs anymore.
  14 *
  15 *
  16 *  Changelog:
  17 *  17-Jan-2005
  18 *  Allan Bezerra
  19 *  Bruna Moreira <bruna.moreira@indt.org.br>
  20 *  Edjard Mota <edjard.mota@indt.org.br>
  21 *  Ilias Biris <ilias.biris@indt.org.br>
  22 *  Mauricio Lin <mauricio.lin@indt.org.br>
  23 *
  24 *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
  25 *
  26 *  A new process specific entry (smaps) included in /proc. It shows the
  27 *  size of rss for each memory area. The maps entry lacks information
  28 *  about physical memory size (rss) for each mapped file, i.e.,
  29 *  rss information for executables and library files.
  30 *  This additional information is useful for any tools that need to know
  31 *  about physical memory consumption for a process specific library.
  32 *
  33 *  Changelog:
  34 *  21-Feb-2005
  35 *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
  36 *  Pud inclusion in the page table walking.
  37 *
  38 *  ChangeLog:
  39 *  10-Mar-2005
  40 *  10LE Instituto Nokia de Tecnologia - INdT:
  41 *  A better way to walks through the page table as suggested by Hugh Dickins.
  42 *
  43 *  Simo Piiroinen <simo.piiroinen@nokia.com>:
  44 *  Smaps information related to shared, private, clean and dirty pages.
  45 *
  46 *  Paul Mundt <paul.mundt@nokia.com>:
  47 *  Overall revision about smaps.
  48 */
  49
  50#include <asm/uaccess.h>
  51
  52#include <linux/errno.h>
  53#include <linux/time.h>
  54#include <linux/proc_fs.h>
  55#include <linux/stat.h>
  56#include <linux/init.h>
  57#include <linux/capability.h>
  58#include <linux/file.h>
  59#include <linux/string.h>
  60#include <linux/seq_file.h>
  61#include <linux/namei.h>
  62#include <linux/mnt_namespace.h>
  63#include <linux/mm.h>
  64#include <linux/rcupdate.h>
  65#include <linux/kallsyms.h>
  66#include <linux/resource.h>
  67#include <linux/module.h>
  68#include <linux/mount.h>
  69#include <linux/security.h>
  70#include <linux/ptrace.h>
  71#include <linux/cgroup.h>
  72#include <linux/cpuset.h>
  73#include <linux/audit.h>
  74#include <linux/poll.h>
  75#include <linux/nsproxy.h>
  76#include <linux/oom.h>
  77#include <linux/elf.h>
  78#include <linux/pid_namespace.h>
  79#include "internal.h"
  80
  81/* NOTE:
  82 *      Implementing inode permission operations in /proc is almost
  83 *      certainly an error.  Permission checks need to happen during
  84 *      each system call not at open time.  The reason is that most of
  85 *      what we wish to check for permissions in /proc varies at runtime.
  86 *
  87 *      The classic example of a problem is opening file descriptors
  88 *      in /proc for a task before it execs a suid executable.
  89 */
  90
  91struct pid_entry {
  92        char *name;
  93        int len;
  94        mode_t mode;
  95        const struct inode_operations *iop;
  96        const struct file_operations *fop;
  97        union proc_op op;
  98};
  99
 100#define NOD(NAME, MODE, IOP, FOP, OP) {                 \
 101        .name = (NAME),                                 \
 102        .len  = sizeof(NAME) - 1,                       \
 103        .mode = MODE,                                   \
 104        .iop  = IOP,                                    \
 105        .fop  = FOP,                                    \
 106        .op   = OP,                                     \
 107}
 108
 109#define DIR(NAME, MODE, OTYPE)                                                  \
 110        NOD(NAME, (S_IFDIR|(MODE)),                                             \
 111                &proc_##OTYPE##_inode_operations, &proc_##OTYPE##_operations,   \
 112                {} )
 113#define LNK(NAME, OTYPE)                                        \
 114        NOD(NAME, (S_IFLNK|S_IRWXUGO),                          \
 115                &proc_pid_link_inode_operations, NULL,          \
 116                { .proc_get_link = &proc_##OTYPE##_link } )
 117#define REG(NAME, MODE, OTYPE)                          \
 118        NOD(NAME, (S_IFREG|(MODE)), NULL,               \
 119                &proc_##OTYPE##_operations, {})
 120#define INF(NAME, MODE, OTYPE)                          \
 121        NOD(NAME, (S_IFREG|(MODE)),                     \
 122                NULL, &proc_info_file_operations,       \
 123                { .proc_read = &proc_##OTYPE } )
 124#define ONE(NAME, MODE, OTYPE)                          \
 125        NOD(NAME, (S_IFREG|(MODE)),                     \
 126                NULL, &proc_single_file_operations,     \
 127                { .proc_show = &proc_##OTYPE } )
 128
 129/*
 130 * Count the number of hardlinks for the pid_entry table, excluding the .
 131 * and .. links.
 132 */
 133static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
 134        unsigned int n)
 135{
 136        unsigned int i;
 137        unsigned int count;
 138
 139        count = 0;
 140        for (i = 0; i < n; ++i) {
 141                if (S_ISDIR(entries[i].mode))
 142                        ++count;
 143        }
 144
 145        return count;
 146}
 147
 148int maps_protect;
 149EXPORT_SYMBOL(maps_protect);
 150
 151static struct fs_struct *get_fs_struct(struct task_struct *task)
 152{
 153        struct fs_struct *fs;
 154        task_lock(task);
 155        fs = task->fs;
 156        if(fs)
 157                atomic_inc(&fs->count);
 158        task_unlock(task);
 159        return fs;
 160}
 161
 162static int get_nr_threads(struct task_struct *tsk)
 163{
 164        /* Must be called with the rcu_read_lock held */
 165        unsigned long flags;
 166        int count = 0;
 167
 168        if (lock_task_sighand(tsk, &flags)) {
 169                count = atomic_read(&tsk->signal->count);
 170                unlock_task_sighand(tsk, &flags);
 171        }
 172        return count;
 173}
 174
 175static int proc_cwd_link(struct inode *inode, struct path *path)
 176{
 177        struct task_struct *task = get_proc_task(inode);
 178        struct fs_struct *fs = NULL;
 179        int result = -ENOENT;
 180
 181        if (task) {
 182                fs = get_fs_struct(task);
 183                put_task_struct(task);
 184        }
 185        if (fs) {
 186                read_lock(&fs->lock);
 187                *path = fs->pwd;
 188                path_get(&fs->pwd);
 189                read_unlock(&fs->lock);
 190                result = 0;
 191                put_fs_struct(fs);
 192        }
 193        return result;
 194}
 195
 196static int proc_root_link(struct inode *inode, struct path *path)
 197{
 198        struct task_struct *task = get_proc_task(inode);
 199        struct fs_struct *fs = NULL;
 200        int result = -ENOENT;
 201
 202        if (task) {
 203                fs = get_fs_struct(task);
 204                put_task_struct(task);
 205        }
 206        if (fs) {
 207                read_lock(&fs->lock);
 208                *path = fs->root;
 209                path_get(&fs->root);
 210                read_unlock(&fs->lock);
 211                result = 0;
 212                put_fs_struct(fs);
 213        }
 214        return result;
 215}
 216
 217#define MAY_PTRACE(task) \
 218        (task == current || \
 219        (task->parent == current && \
 220        (task->ptrace & PT_PTRACED) && \
 221         (task_is_stopped_or_traced(task)) && \
 222         security_ptrace(current,task) == 0))
 223
 224struct mm_struct *mm_for_maps(struct task_struct *task)
 225{
 226        struct mm_struct *mm = get_task_mm(task);
 227        if (!mm)
 228                return NULL;
 229        down_read(&mm->mmap_sem);
 230        task_lock(task);
 231        if (task->mm != mm)
 232                goto out;
 233        if (task->mm != current->mm && __ptrace_may_attach(task) < 0)
 234                goto out;
 235        task_unlock(task);
 236        return mm;
 237out:
 238        task_unlock(task);
 239        up_read(&mm->mmap_sem);
 240        mmput(mm);
 241        return NULL;
 242}
 243
 244static int proc_pid_cmdline(struct task_struct *task, char * buffer)
 245{
 246        int res = 0;
 247        unsigned int len;
 248        struct mm_struct *mm = get_task_mm(task);
 249        if (!mm)
 250                goto out;
 251        if (!mm->arg_end)
 252                goto out_mm;    /* Shh! No looking before we're done */
 253
 254        len = mm->arg_end - mm->arg_start;
 255 
 256        if (len > PAGE_SIZE)
 257                len = PAGE_SIZE;
 258 
 259        res = access_process_vm(task, mm->arg_start, buffer, len, 0);
 260
 261        // If the nul at the end of args has been overwritten, then
 262        // assume application is using setproctitle(3).
 263        if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {
 264                len = strnlen(buffer, res);
 265                if (len < res) {
 266                    res = len;
 267                } else {
 268                        len = mm->env_end - mm->env_start;
 269                        if (len > PAGE_SIZE - res)
 270                                len = PAGE_SIZE - res;
 271                        res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
 272                        res = strnlen(buffer, res);
 273                }
 274        }
 275out_mm:
 276        mmput(mm);
 277out:
 278        return res;
 279}
 280
 281static int proc_pid_auxv(struct task_struct *task, char *buffer)
 282{
 283        int res = 0;
 284        struct mm_struct *mm = get_task_mm(task);
 285        if (mm) {
 286                unsigned int nwords = 0;
 287                do
 288                        nwords += 2;
 289                while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
 290                res = nwords * sizeof(mm->saved_auxv[0]);
 291                if (res > PAGE_SIZE)
 292                        res = PAGE_SIZE;
 293                memcpy(buffer, mm->saved_auxv, res);
 294                mmput(mm);
 295        }
 296        return res;
 297}
 298
 299
 300#ifdef CONFIG_KALLSYMS
 301/*
 302 * Provides a wchan file via kallsyms in a proper one-value-per-file format.
 303 * Returns the resolved symbol.  If that fails, simply return the address.
 304 */
 305static int proc_pid_wchan(struct task_struct *task, char *buffer)
 306{
 307        unsigned long wchan;
 308        char symname[KSYM_NAME_LEN];
 309
 310        wchan = get_wchan(task);
 311
 312        if (lookup_symbol_name(wchan, symname) < 0)
 313                return sprintf(buffer, "%lu", wchan);
 314        else
 315                return sprintf(buffer, "%s", symname);
 316}
 317#endif /* CONFIG_KALLSYMS */
 318
 319#ifdef CONFIG_SCHEDSTATS
 320/*
 321 * Provides /proc/PID/schedstat
 322 */
 323static int proc_pid_schedstat(struct task_struct *task, char *buffer)
 324{
 325        return sprintf(buffer, "%llu %llu %lu\n",
 326                        task->sched_info.cpu_time,
 327                        task->sched_info.run_delay,
 328                        task->sched_info.pcount);
 329}
 330#endif
 331
 332#ifdef CONFIG_LATENCYTOP
 333static int lstats_show_proc(struct seq_file *m, void *v)
 334{
 335        int i;
 336        struct inode *inode = m->private;
 337        struct task_struct *task = get_proc_task(inode);
 338
 339        if (!task)
 340                return -ESRCH;
 341        seq_puts(m, "Latency Top version : v0.1\n");
 342        for (i = 0; i < 32; i++) {
 343                if (task->latency_record[i].backtrace[0]) {
 344                        int q;
 345                        seq_printf(m, "%i %li %li ",
 346                                task->latency_record[i].count,
 347                                task->latency_record[i].time,
 348                                task->latency_record[i].max);
 349                        for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
 350                                char sym[KSYM_NAME_LEN];
 351                                char *c;
 352                                if (!task->latency_record[i].backtrace[q])
 353                                        break;
 354                                if (task->latency_record[i].backtrace[q] == ULONG_MAX)
 355                                        break;
 356                                sprint_symbol(sym, task->latency_record[i].backtrace[q]);
 357                                c = strchr(sym, '+');
 358                                if (c)
 359                                        *c = 0;
 360                                seq_printf(m, "%s ", sym);
 361                        }
 362                        seq_printf(m, "\n");
 363                }
 364
 365        }
 366        put_task_struct(task);
 367        return 0;
 368}
 369
 370static int lstats_open(struct inode *inode, struct file *file)
 371{
 372        return single_open(file, lstats_show_proc, inode);
 373}
 374
 375static ssize_t lstats_write(struct file *file, const char __user *buf,
 376                            size_t count, loff_t *offs)
 377{
 378        struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
 379
 380        if (!task)
 381                return -ESRCH;
 382        clear_all_latency_tracing(task);
 383        put_task_struct(task);
 384
 385        return count;
 386}
 387
 388static const struct file_operations proc_lstats_operations = {
 389        .open           = lstats_open,
 390        .read           = seq_read,
 391        .write          = lstats_write,
 392        .llseek         = seq_lseek,
 393        .release        = single_release,
 394};
 395
 396#endif
 397
 398/* The badness from the OOM killer */
 399unsigned long badness(struct task_struct *p, unsigned long uptime);
 400static int proc_oom_score(struct task_struct *task, char *buffer)
 401{
 402        unsigned long points;
 403        struct timespec uptime;
 404
 405        do_posix_clock_monotonic_gettime(&uptime);
 406        read_lock(&tasklist_lock);
 407        points = badness(task, uptime.tv_sec);
 408        read_unlock(&tasklist_lock);
 409        return sprintf(buffer, "%lu\n", points);
 410}
 411
 412struct limit_names {
 413        char *name;
 414        char *unit;
 415};
 416
 417static const struct limit_names lnames[RLIM_NLIMITS] = {
 418        [RLIMIT_CPU] = {"Max cpu time", "ms"},
 419        [RLIMIT_FSIZE] = {"Max file size", "bytes"},
 420        [RLIMIT_DATA] = {"Max data size", "bytes"},
 421        [RLIMIT_STACK] = {"Max stack size", "bytes"},
 422        [RLIMIT_CORE] = {"Max core file size", "bytes"},
 423        [RLIMIT_RSS] = {"Max resident set", "bytes"},
 424        [RLIMIT_NPROC] = {"Max processes", "processes"},
 425        [RLIMIT_NOFILE] = {"Max open files", "files"},
 426        [RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},
 427        [RLIMIT_AS] = {"Max address space", "bytes"},
 428        [RLIMIT_LOCKS] = {"Max file locks", "locks"},
 429        [RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},
 430        [RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},
 431        [RLIMIT_NICE] = {"Max nice priority", NULL},
 432        [RLIMIT_RTPRIO] = {"Max realtime priority", NULL},
 433        [RLIMIT_RTTIME] = {"Max realtime timeout", "us"},
 434};
 435
 436/* Display limits for a process */
 437static int proc_pid_limits(struct task_struct *task, char *buffer)
 438{
 439        unsigned int i;
 440        int count = 0;
 441        unsigned long flags;
 442        char *bufptr = buffer;
 443
 444        struct rlimit rlim[RLIM_NLIMITS];
 445
 446        rcu_read_lock();
 447        if (!lock_task_sighand(task,&flags)) {
 448                rcu_read_unlock();
 449                return 0;
 450        }
 451        memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
 452        unlock_task_sighand(task, &flags);
 453        rcu_read_unlock();
 454
 455        /*
 456         * print the file header
 457         */
 458        count += sprintf(&bufptr[count], "%-25s %-20s %-20s %-10s\n",
 459                        "Limit", "Soft Limit", "Hard Limit", "Units");
 460
 461        for (i = 0; i < RLIM_NLIMITS; i++) {
 462                if (rlim[i].rlim_cur == RLIM_INFINITY)
 463                        count += sprintf(&bufptr[count], "%-25s %-20s ",
 464                                         lnames[i].name, "unlimited");
 465                else
 466                        count += sprintf(&bufptr[count], "%-25s %-20lu ",
 467                                         lnames[i].name, rlim[i].rlim_cur);
 468
 469                if (rlim[i].rlim_max == RLIM_INFINITY)
 470                        count += sprintf(&bufptr[count], "%-20s ", "unlimited");
 471                else
 472                        count += sprintf(&bufptr[count], "%-20lu ",
 473                                         rlim[i].rlim_max);
 474
 475                if (lnames[i].unit)
 476                        count += sprintf(&bufptr[count], "%-10s\n",
 477                                         lnames[i].unit);
 478                else
 479                        count += sprintf(&bufptr[count], "\n");
 480        }
 481
 482        return count;
 483}
 484
 485/************************************************************************/
 486/*                       Here the fs part begins                        */
 487/************************************************************************/
 488
 489/* permission checks */
 490static int proc_fd_access_allowed(struct inode *inode)
 491{
 492        struct task_struct *task;
 493        int allowed = 0;
 494        /* Allow access to a task's file descriptors if it is us or we
 495         * may use ptrace attach to the process and find out that
 496         * information.
 497         */
 498        task = get_proc_task(inode);
 499        if (task) {
 500                allowed = ptrace_may_attach(task);
 501                put_task_struct(task);
 502        }
 503        return allowed;
 504}
 505
 506static int proc_setattr(struct dentry *dentry, struct iattr *attr)
 507{
 508        int error;
 509        struct inode *inode = dentry->d_inode;
 510
 511        if (attr->ia_valid & ATTR_MODE)
 512                return -EPERM;
 513
 514        error = inode_change_ok(inode, attr);
 515        if (!error)
 516                error = inode_setattr(inode, attr);
 517        return error;
 518}
 519
 520static const struct inode_operations proc_def_inode_operations = {
 521        .setattr        = proc_setattr,
 522};
 523
 524extern const struct seq_operations mounts_op;
 525struct proc_mounts {
 526        struct seq_file m;
 527        int event;
 528};
 529
 530static int mounts_open(struct inode *inode, struct file *file)
 531{
 532        struct task_struct *task = get_proc_task(inode);
 533        struct nsproxy *nsp;
 534        struct mnt_namespace *ns = NULL;
 535        struct proc_mounts *p;
 536        int ret = -EINVAL;
 537
 538        if (task) {
 539                rcu_read_lock();
 540                nsp = task_nsproxy(task);
 541                if (nsp) {
 542                        ns = nsp->mnt_ns;
 543                        if (ns)
 544                                get_mnt_ns(ns);
 545                }
 546                rcu_read_unlock();
 547
 548                put_task_struct(task);
 549        }
 550
 551        if (ns) {
 552                ret = -ENOMEM;
 553                p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
 554                if (p) {
 555                        file->private_data = &p->m;
 556                        ret = seq_open(file, &mounts_op);
 557                        if (!ret) {
 558                                p->m.private = ns;
 559                                p->event = ns->event;
 560                                return 0;
 561                        }
 562                        kfree(p);
 563                }
 564                put_mnt_ns(ns);
 565        }
 566        return ret;
 567}
 568
 569static int mounts_release(struct inode *inode, struct file *file)
 570{
 571        struct seq_file *m = file->private_data;
 572        struct mnt_namespace *ns = m->private;
 573        put_mnt_ns(ns);
 574        return seq_release(inode, file);
 575}
 576
 577static unsigned mounts_poll(struct file *file, poll_table *wait)
 578{
 579        struct proc_mounts *p = file->private_data;
 580        struct mnt_namespace *ns = p->m.private;
 581        unsigned res = 0;
 582
 583        poll_wait(file, &ns->poll, wait);
 584
 585        spin_lock(&vfsmount_lock);
 586        if (p->event != ns->event) {
 587                p->event = ns->event;
 588                res = POLLERR;
 589        }
 590        spin_unlock(&vfsmount_lock);
 591
 592        return res;
 593}
 594
 595static const struct file_operations proc_mounts_operations = {
 596        .open           = mounts_open,
 597        .read           = seq_read,
 598        .llseek         = seq_lseek,
 599        .release        = mounts_release,
 600        .poll           = mounts_poll,
 601};
 602
 603extern const struct seq_operations mountstats_op;
 604static int mountstats_open(struct inode *inode, struct file *file)
 605{
 606        int ret = seq_open(file, &mountstats_op);
 607
 608        if (!ret) {
 609                struct seq_file *m = file->private_data;
 610                struct nsproxy *nsp;
 611                struct mnt_namespace *mnt_ns = NULL;
 612                struct task_struct *task = get_proc_task(inode);
 613
 614                if (task) {
 615                        rcu_read_lock();
 616                        nsp = task_nsproxy(task);
 617                        if (nsp) {
 618                                mnt_ns = nsp->mnt_ns;
 619                                if (mnt_ns)
 620                                        get_mnt_ns(mnt_ns);
 621                        }
 622                        rcu_read_unlock();
 623
 624                        put_task_struct(task);
 625                }
 626
 627                if (mnt_ns)
 628                        m->private = mnt_ns;
 629                else {
 630                        seq_release(inode, file);
 631                        ret = -EINVAL;
 632                }
 633        }
 634        return ret;
 635}
 636
 637static const struct file_operations proc_mountstats_operations = {
 638        .open           = mountstats_open,
 639        .read           = seq_read,
 640        .llseek         = seq_lseek,
 641        .release        = mounts_release,
 642};
 643
 644#define PROC_BLOCK_SIZE (3*1024)                /* 4K page size but our output routines use some slack for overruns */
 645
 646static ssize_t proc_info_read(struct file * file, char __user * buf,
 647                          size_t count, loff_t *ppos)
 648{
 649        struct inode * inode = file->f_path.dentry->d_inode;
 650        unsigned long page;
 651        ssize_t length;
 652        struct task_struct *task = get_proc_task(inode);
 653
 654        length = -ESRCH;
 655        if (!task)
 656                goto out_no_task;
 657
 658        if (count > PROC_BLOCK_SIZE)
 659                count = PROC_BLOCK_SIZE;
 660
 661        length = -ENOMEM;
 662        if (!(page = __get_free_page(GFP_TEMPORARY)))
 663                goto out;
 664
 665        length = PROC_I(inode)->op.proc_read(task, (char*)page);
 666
 667        if (length >= 0)
 668                length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
 669        free_page(page);
 670out:
 671        put_task_struct(task);
 672out_no_task:
 673        return length;
 674}
 675
 676static const struct file_operations proc_info_file_operations = {
 677        .read           = proc_info_read,
 678};
 679
 680static int proc_single_show(struct seq_file *m, void *v)
 681{
 682        struct inode *inode = m->private;
 683        struct pid_namespace *ns;
 684        struct pid *pid;
 685        struct task_struct *task;
 686        int ret;
 687
 688        ns = inode->i_sb->s_fs_info;
 689        pid = proc_pid(inode);
 690        task = get_pid_task(pid, PIDTYPE_PID);
 691        if (!task)
 692                return -ESRCH;
 693
 694        ret = PROC_I(inode)->op.proc_show(m, ns, pid, task);
 695
 696        put_task_struct(task);
 697        return ret;
 698}
 699
 700static int proc_single_open(struct inode *inode, struct file *filp)
 701{
 702        int ret;
 703        ret = single_open(filp, proc_single_show, NULL);
 704        if (!ret) {
 705                struct seq_file *m = filp->private_data;
 706
 707                m->private = inode;
 708        }
 709        return ret;
 710}
 711
 712static const struct file_operations proc_single_file_operations = {
 713        .open           = proc_single_open,
 714        .read           = seq_read,
 715        .llseek         = seq_lseek,
 716        .release        = single_release,
 717};
 718
 719static int mem_open(struct inode* inode, struct file* file)
 720{
 721        file->private_data = (void*)((long)current->self_exec_id);
 722        return 0;
 723}
 724
 725static ssize_t mem_read(struct file * file, char __user * buf,
 726                        size_t count, loff_t *ppos)
 727{
 728        struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
 729        char *page;
 730        unsigned long src = *ppos;
 731        int ret = -ESRCH;
 732        struct mm_struct *mm;
 733
 734        if (!task)
 735                goto out_no_task;
 736
 737        if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
 738                goto out;
 739
 740        ret = -ENOMEM;
 741        page = (char *)__get_free_page(GFP_TEMPORARY);
 742        if (!page)
 743                goto out;
 744
 745        ret = 0;
 746 
 747        mm = get_task_mm(task);
 748        if (!mm)
 749                goto out_free;
 750
 751        ret = -EIO;
 752 
 753        if (file->private_data != (void*)((long)current->self_exec_id))
 754                goto out_put;
 755
 756        ret = 0;
 757 
 758        while (count > 0) {
 759                int this_len, retval;
 760
 761                this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
 762                retval = access_process_vm(task, src, page, this_len, 0);
 763                if (!retval || !MAY_PTRACE(task) || !ptrace_may_attach(task)) {
 764                        if (!ret)
 765                                ret = -EIO;
 766                        break;
 767                }
 768
 769                if (copy_to_user(buf, page, retval)) {
 770                        ret = -EFAULT;
 771                        break;
 772                }
 773 
 774                ret += retval;
 775                src += retval;
 776                buf += retval;
 777                count -= retval;
 778        }
 779        *ppos = src;
 780
 781out_put:
 782        mmput(mm);
 783out_free:
 784        free_page((unsigned long) page);
 785out:
 786        put_task_struct(task);
 787out_no_task:
 788        return ret;
 789}
 790
 791#define mem_write NULL
 792
 793#ifndef mem_write
 794/* This is a security hazard */
 795static ssize_t mem_write(struct file * file, const char __user *buf,
 796                         size_t count, loff_t *ppos)
 797{
 798        int copied;
 799        char *page;
 800        struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
 801        unsigned long dst = *ppos;
 802
 803        copied = -ESRCH;
 804        if (!task)
 805                goto out_no_task;
 806
 807        if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
 808                goto out;
 809
 810        copied = -ENOMEM;
 811        page = (char *)__get_free_page(GFP_TEMPORARY);
 812        if (!page)
 813                goto out;
 814
 815        copied = 0;
 816        while (count > 0) {
 817                int this_len, retval;
 818
 819                this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
 820                if (copy_from_user(page, buf, this_len)) {
 821                        copied = -EFAULT;
 822                        break;
 823                }
 824                retval = access_process_vm(task, dst, page, this_len, 1);
 825                if (!retval) {
 826                        if (!copied)
 827                                copied = -EIO;
 828                        break;
 829                }
 830                copied += retval;
 831                buf += retval;
 832                dst += retval;
 833                count -= retval;                        
 834        }
 835        *ppos = dst;
 836        free_page((unsigned long) page);
 837out:
 838        put_task_struct(task);
 839out_no_task:
 840        return copied;
 841}
 842#endif
 843
 844loff_t mem_lseek(struct file *file, loff_t offset, int orig)
 845{
 846        switch (orig) {
 847        case 0:
 848                file->f_pos = offset;
 849                break;
 850        case 1:
 851                file->f_pos += offset;
 852                break;
 853        default:
 854                return -EINVAL;
 855        }
 856        force_successful_syscall_return();
 857        return file->f_pos;
 858}
 859
 860static const struct file_operations proc_mem_operations = {
 861        .llseek         = mem_lseek,
 862        .read           = mem_read,
 863        .write          = mem_write,
 864        .open           = mem_open,
 865};
 866
 867static ssize_t environ_read(struct file *file, char __user *buf,
 868                        size_t count, loff_t *ppos)
 869{
 870        struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
 871        char *page;
 872        unsigned long src = *ppos;
 873        int ret = -ESRCH;
 874        struct mm_struct *mm;
 875
 876        if (!task)
 877                goto out_no_task;
 878
 879        if (!ptrace_may_attach(task))
 880                goto out;
 881
 882        ret = -ENOMEM;
 883        page = (char *)__get_free_page(GFP_TEMPORARY);
 884        if (!page)
 885                goto out;
 886
 887        ret = 0;
 888
 889        mm = get_task_mm(task);
 890        if (!mm)
 891                goto out_free;
 892
 893        while (count > 0) {
 894                int this_len, retval, max_len;
 895
 896                this_len = mm->env_end - (mm->env_start + src);
 897
 898                if (this_len <= 0)
 899                        break;
 900
 901                max_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
 902                this_len = (this_len > max_len) ? max_len : this_len;
 903
 904                retval = access_process_vm(task, (mm->env_start + src),
 905                        page, this_len, 0);
 906
 907                if (retval <= 0) {
 908                        ret = retval;
 909                        break;
 910                }
 911
 912                if (copy_to_user(buf, page, retval)) {
 913                        ret = -EFAULT;
 914                        break;
 915                }
 916
 917                ret += retval;
 918                src += retval;
 919                buf += retval;
 920                count -= retval;
 921        }
 922        *ppos = src;
 923
 924        mmput(mm);
 925out_free:
 926        free_page((unsigned long) page);
 927out:
 928        put_task_struct(task);
 929out_no_task:
 930        return ret;
 931}
 932
 933static const struct file_operations proc_environ_operations = {
 934        .read           = environ_read,
 935};
 936
 937static ssize_t oom_adjust_read(struct file *file, char __user *buf,
 938                                size_t count, loff_t *ppos)
 939{
 940        struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
 941        char buffer[PROC_NUMBUF];
 942        size_t len;
 943        int oom_adjust;
 944
 945        if (!task)
 946                return -ESRCH;
 947        oom_adjust = task->oomkilladj;
 948        put_task_struct(task);
 949
 950        len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
 951
 952        return simple_read_from_buffer(buf, count, ppos, buffer, len);
 953}
 954
 955static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
 956                                size_t count, loff_t *ppos)
 957{
 958        struct task_struct *task;
 959        char buffer[PROC_NUMBUF], *end;
 960        int oom_adjust;
 961
 962        memset(buffer, 0, sizeof(buffer));
 963        if (count > sizeof(buffer) - 1)
 964                count = sizeof(buffer) - 1;
 965        if (copy_from_user(buffer, buf, count))
 966                return -EFAULT;
 967        oom_adjust = simple_strtol(buffer, &end, 0);
 968        if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&
 969             oom_adjust != OOM_DISABLE)
 970                return -EINVAL;
 971        if (*end == '\n')
 972                end++;
 973        task = get_proc_task(file->f_path.dentry->d_inode);
 974        if (!task)
 975                return -ESRCH;
 976        if (oom_adjust < task->oomkilladj && !capable(CAP_SYS_RESOURCE)) {
 977                put_task_struct(task);
 978                return -EACCES;
 979        }
 980        task->oomkilladj = oom_adjust;
 981        put_task_struct(task);
 982        if (end - buffer == 0)
 983                return -EIO;
 984        return end - buffer;
 985}
 986
 987static const struct file_operations proc_oom_adjust_operations = {
 988        .read           = oom_adjust_read,
 989        .write          = oom_adjust_write,
 990};
 991
 992#ifdef CONFIG_AUDITSYSCALL
 993#define TMPBUFLEN 21
 994static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
 995                                  size_t count, loff_t *ppos)
 996{
 997        struct inode * inode = file->f_path.dentry->d_inode;
 998        struct task_struct *task = get_proc_task(inode);
 999        ssize_t length;
1000        char tmpbuf[TMPBUFLEN];
1001
1002        if (!task)
1003                return -ESRCH;
1004        length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1005                                audit_get_loginuid(task));
1006        put_task_struct(task);
1007        return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1008}
1009
1010static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
1011                                   size_t count, loff_t *ppos)
1012{
1013        struct inode * inode = file->f_path.dentry->d_inode;
1014        char *page, *tmp;
1015        ssize_t length;
1016        uid_t loginuid;
1017
1018        if (!capable(CAP_AUDIT_CONTROL))
1019                return -EPERM;
1020
1021        if (current != pid_task(proc_pid(inode), PIDTYPE_PID))
1022                return -EPERM;
1023
1024        if (count >= PAGE_SIZE)
1025                count = PAGE_SIZE - 1;
1026
1027        if (*ppos != 0) {
1028                /* No partial writes. */
1029                return -EINVAL;
1030        }
1031        page = (char*)__get_free_page(GFP_TEMPORARY);
1032        if (!page)
1033                return -ENOMEM;
1034        length = -EFAULT;
1035        if (copy_from_user(page, buf, count))
1036                goto out_free_page;
1037
1038        page[count] = '\0';
1039        loginuid = simple_strtoul(page, &tmp, 10);
1040        if (tmp == page) {
1041                length = -EINVAL;
1042                goto out_free_page;
1043
1044        }
1045        length = audit_set_loginuid(current, loginuid);
1046        if (likely(length == 0))
1047                length = count;
1048
1049out_free_page:
1050        free_page((unsigned long) page);
1051        return length;
1052}
1053
1054static const struct file_operations proc_loginuid_operations = {
1055        .read           = proc_loginuid_read,
1056        .write          = proc_loginuid_write,
1057};
1058
1059static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
1060                                  size_t count, loff_t *ppos)
1061{
1062        struct inode * inode = file->f_path.dentry->d_inode;
1063        struct task_struct *task = get_proc_task(inode);
1064        ssize_t length;
1065        char tmpbuf[TMPBUFLEN];
1066
1067        if (!task)
1068                return -ESRCH;
1069        length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1070                                audit_get_sessionid(task));
1071        put_task_struct(task);
1072        return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1073}
1074
1075static const struct file_operations proc_sessionid_operations = {
1076        .read           = proc_sessionid_read,
1077};
1078#endif
1079
1080#ifdef CONFIG_FAULT_INJECTION
1081static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
1082                                      size_t count, loff_t *ppos)
1083{
1084        struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
1085        char buffer[PROC_NUMBUF];
1086        size_t len;
1087        int make_it_fail;
1088
1089        if (!task)
1090                return -ESRCH;
1091        make_it_fail = task->make_it_fail;
1092        put_task_struct(task);
1093
1094        len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);
1095
1096        return simple_read_from_buffer(buf, count, ppos, buffer, len);
1097}
1098
1099static ssize_t proc_fault_inject_write(struct file * file,
1100                        const char __user * buf, size_t count, loff_t *ppos)
1101{
1102        struct task_struct *task;
1103        char buffer[PROC_NUMBUF], *end;
1104        int make_it_fail;
1105
1106        if (!capable(CAP_SYS_RESOURCE))
1107                return -EPERM;
1108        memset(buffer, 0, sizeof(buffer));
1109        if (count > sizeof(buffer) - 1)
1110                count = sizeof(buffer) - 1;
1111        if (copy_from_user(buffer, buf, count))
1112                return -EFAULT;
1113        make_it_fail = simple_strtol(buffer, &end, 0);
1114        if (*end == '\n')
1115                end++;
1116        task = get_proc_task(file->f_dentry->d_inode);
1117        if (!task)
1118                return -ESRCH;
1119        task->make_it_fail = make_it_fail;
1120        put_task_struct(task);
1121        if (end - buffer == 0)
1122                return -EIO;
1123        return end - buffer;
1124}
1125
1126static const struct file_operations proc_fault_inject_operations = {
1127        .read           = proc_fault_inject_read,
1128        .write          = proc_fault_inject_write,
1129};
1130#endif
1131
1132
1133#ifdef CONFIG_SCHED_DEBUG
1134/*
1135 * Print out various scheduling related per-task fields:
1136 */
1137static int sched_show(struct seq_file *m, void *v)
1138{
1139        struct inode *inode = m->private;
1140        struct task_struct *p;
1141
1142        WARN_ON(!inode);
1143
1144        p = get_proc_task(inode);
1145        if (!p)
1146                return -ESRCH;
1147        proc_sched_show_task(p, m);
1148
1149        put_task_struct(p);
1150
1151        return 0;
1152}
1153
1154static ssize_t
1155sched_write(struct file *file, const char __user *buf,
1156            size_t count, loff_t *offset)
1157{
1158        struct inode *inode = file->f_path.dentry->d_inode;
1159        struct task_struct *p;
1160
1161        WARN_ON(!inode);
1162
1163        p = get_proc_task(inode);
1164        if (!p)
1165                return -ESRCH;
1166        proc_sched_set_task(p);
1167
1168        put_task_struct(p);
1169
1170        return count;
1171}
1172
1173static int sched_open(struct inode *inode, struct file *filp)
1174{
1175        int ret;
1176
1177        ret = single_open(filp, sched_show, NULL);
1178        if (!ret) {
1179                struct seq_file *m = filp->private_data;
1180
1181                m->private = inode;
1182        }
1183        return ret;
1184}
1185
1186static const struct file_operations proc_pid_sched_operations = {
1187        .open           = sched_open,
1188        .read           = seq_read,
1189        .write          = sched_write,
1190        .llseek         = seq_lseek,
1191        .release        = single_release,
1192};
1193
1194#endif
1195
1196static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
1197{
1198        struct inode *inode = dentry->d_inode;
1199        int error = -EACCES;
1200
1201        /* We don't need a base pointer in the /proc filesystem */
1202        path_put(&nd->path);
1203
1204        /* Are we allowed to snoop on the tasks file descriptors? */
1205        if (!proc_fd_access_allowed(inode))
1206                goto out;
1207
1208        error = PROC_I(inode)->op.proc_get_link(inode, &nd->path);
1209        nd->last_type = LAST_BIND;
1210out:
1211        return ERR_PTR(error);
1212}
1213
1214static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
1215{
1216        char *tmp = (char*)__get_free_page(GFP_TEMPORARY);
1217        char *pathname;
1218        int len;
1219
1220        if (!tmp)
1221                return -ENOMEM;
1222
1223        pathname = d_path(path, tmp, PAGE_SIZE);
1224        len = PTR_ERR(pathname);
1225        if (IS_ERR(pathname))
1226                goto out;
1227        len = tmp + PAGE_SIZE - 1 - pathname;
1228
1229        if (len > buflen)
1230                len = buflen;
1231        if (copy_to_user(buffer, pathname, len))
1232                len = -EFAULT;
1233 out:
1234        free_page((unsigned long)tmp);
1235        return len;
1236}
1237
1238static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
1239{
1240        int error = -EACCES;
1241        struct inode *inode = dentry->d_inode;
1242        struct path path;
1243
1244        /* Are we allowed to snoop on the tasks file descriptors? */
1245        if (!proc_fd_access_allowed(inode))
1246                goto out;
1247
1248        error = PROC_I(inode)->op.proc_get_link(inode, &path);
1249        if (error)
1250                goto out;
1251
1252        error = do_proc_readlink(&path, buffer, buflen);
1253        path_put(&path);
1254out:
1255        return error;
1256}
1257
1258static const struct inode_operations proc_pid_link_inode_operations = {
1259        .readlink       = proc_pid_readlink,
1260        .follow_link    = proc_pid_follow_link,
1261        .setattr        = proc_setattr,
1262};
1263
1264
1265/* building an inode */
1266
1267static int task_dumpable(struct task_struct *task)
1268{
1269        int dumpable = 0;
1270        struct mm_struct *mm;
1271
1272        task_lock(task);
1273        mm = task->mm;
1274        if (mm)
1275                dumpable = get_dumpable(mm);
1276        task_unlock(task);
1277        if(dumpable == 1)
1278                return 1;
1279        return 0;
1280}
1281
1282
1283static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task)
1284{
1285        struct inode * inode;
1286        struct proc_inode *ei;
1287
1288        /* We need a new inode */
1289
1290        inode = new_inode(sb);
1291        if (!inode)
1292                goto out;
1293
1294        /* Common stuff */
1295        ei = PROC_I(inode);
1296        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
1297        inode->i_op = &proc_def_inode_operations;
1298
1299        /*
1300         * grab the reference to task.
1301         */
1302        ei->pid = get_task_pid(task, PIDTYPE_PID);
1303        if (!ei->pid)
1304                goto out_unlock;
1305
1306        inode->i_uid = 0;
1307        inode->i_gid = 0;
1308        if (task_dumpable(task)) {
1309                inode->i_uid = task->euid;
1310                inode->i_gid = task->egid;
1311        }
1312        security_task_to_inode(task, inode);
1313
1314out:
1315        return inode;
1316
1317out_unlock:
1318        iput(inode);
1319        return NULL;
1320}
1321
1322static int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
1323{
1324        struct inode *inode = dentry->d_inode;
1325        struct task_struct *task;
1326        generic_fillattr(inode, stat);
1327
1328        rcu_read_lock();
1329        stat->uid = 0;
1330        stat->gid = 0;
1331        task = pid_task(proc_pid(inode), PIDTYPE_PID);
1332        if (task) {
1333                if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
1334                    task_dumpable(task)) {
1335                        stat->uid = task->euid;
1336                        stat->gid = task->egid;
1337                }
1338        }
1339        rcu_read_unlock();
1340        return 0;
1341}
1342
1343/* dentry stuff */
1344
1345/*
1346 *      Exceptional case: normally we are not allowed to unhash a busy
1347 * directory. In this case, however, we can do it - no aliasing problems
1348 * due to the way we treat inodes.
1349 *
1350 * Rewrite the inode's ownerships here because the owning task may have
1351 * performed a setuid(), etc.
1352 *
1353 * Before the /proc/pid/status file was created the only way to read
1354 * the effective uid of a /process was to stat /proc/pid.  Reading
1355 * /proc/pid/status is slow enough that procps and other packages
1356 * kept stating /proc/pid.  To keep the rules in /proc simple I have
1357 * made this apply to all per process world readable and executable
1358 * directories.
1359 */
1360static int pid_revalidate(struct dentry *dentry, struct nameidata *nd)
1361{
1362        struct inode *inode = dentry->d_inode;
1363        struct task_struct *task = get_proc_task(inode);
1364        if (task) {
1365                if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
1366                    task_dumpable(task)) {
1367                        inode->i_uid = task->euid;
1368                        inode->i_gid = task->egid;
1369                } else {
1370                        inode->i_uid = 0;
1371                        inode->i_gid = 0;
1372                }
1373                inode->i_mode &= ~(S_ISUID | S_ISGID);
1374                security_task_to_inode(task, inode);
1375                put_task_struct(task);
1376                return 1;
1377        }
1378        d_drop(dentry);
1379        return 0;
1380}
1381
1382static int pid_delete_dentry(struct dentry * dentry)
1383{
1384        /* Is the task we represent dead?
1385         * If so, then don't put the dentry on the lru list,
1386         * kill it immediately.
1387         */
1388        return !proc_pid(dentry->d_inode)->tasks[PIDTYPE_PID].first;
1389}
1390
1391static struct dentry_operations pid_dentry_operations =
1392{
1393        .d_revalidate   = pid_revalidate,
1394        .d_delete       = pid_delete_dentry,
1395};
1396
1397/* Lookups */
1398
1399typedef struct dentry *instantiate_t(struct inode *, struct dentry *,
1400                                struct task_struct *, const void *);
1401
1402/*
1403 * Fill a directory entry.
1404 *
1405 * If possible create the dcache entry and derive our inode number and
1406 * file type from dcache entry.
1407 *
1408 * Since all of the proc inode numbers are dynamically generated, the inode
1409 * numbers do not exist until the inode is cache.  This means creating the
1410 * the dcache entry in readdir is necessary to keep the inode numbers
1411 * reported by readdir in sync with the inode numbers reported
1412 * by stat.
1413 */
1414static int proc_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
1415        char *name, int len,
1416        instantiate_t instantiate, struct task_struct *task, const void *ptr)
1417{
1418        struct dentry *child, *dir = filp->f_path.dentry;
1419        struct inode *inode;
1420        struct qstr qname;
1421        ino_t ino = 0;
1422        unsigned type = DT_UNKNOWN;
1423
1424        qname.name = name;
1425        qname.len  = len;
1426        qname.hash = full_name_hash(name, len);
1427
1428        child = d_lookup(dir, &qname);
1429        if (!child) {
1430                struct dentry *new;
1431                new = d_alloc(dir, &qname);
1432                if (new) {
1433                        child = instantiate(dir->d_inode, new, task, ptr);
1434                        if (child)
1435                                dput(new);
1436                        else
1437                                child = new;
1438                }
1439        }
1440        if (!child || IS_ERR(child) || !child->d_inode)
1441                goto end_instantiate;
1442        inode = child->d_inode;
1443        if (inode) {
1444                ino = inode->i_ino;
1445                type = inode->i_mode >> 12;
1446        }
1447        dput(child);
1448end_instantiate:
1449        if (!ino)
1450                ino = find_inode_number(dir, &qname);
1451        if (!ino)
1452                ino = 1;
1453        return filldir(dirent, name, len, filp->f_pos, ino, type);
1454}
1455
1456static unsigned name_to_int(struct dentry *dentry)
1457{
1458        const char *name = dentry->d_name.name;
1459        int len = dentry->d_name.len;
1460        unsigned n = 0;
1461
1462        if (len > 1 && *name == '0')
1463                goto out;
1464        while (len-- > 0) {
1465                unsigned c = *name++ - '0';
1466                if (c > 9)
1467                        goto out;
1468                if (n >= (~0U-9)/10)
1469                        goto out;
1470                n *= 10;
1471                n += c;
1472        }
1473        return n;
1474out:
1475        return ~0U;
1476}
1477
1478#define PROC_FDINFO_MAX 64
1479
1480static int proc_fd_info(struct inode *inode, struct path *path, char *info)
1481{
1482        struct task_struct *task = get_proc_task(inode);
1483        struct files_struct *files = NULL;
1484        struct file *file;
1485        int fd = proc_fd(inode);
1486
1487        if (task) {
1488                files = get_files_struct(task);
1489                put_task_struct(task);
1490        }
1491        if (files) {
1492                /*
1493                 * We are not taking a ref to the file structure, so we must
1494                 * hold ->file_lock.
1495                 */
1496                spin_lock(&files->file_lock);
1497                file = fcheck_files(files, fd);
1498                if (file) {
1499                        if (path) {
1500                                *path = file->f_path;
1501                                path_get(&file->f_path);
1502                        }
1503                        if (info)
1504                                snprintf(info, PROC_FDINFO_MAX,
1505                                         "pos:\t%lli\n"
1506                                         "flags:\t0%o\n",
1507                                         (long long) file->f_pos,
1508                                         file->f_flags);
1509                        spin_unlock(&files->file_lock);
1510                        put_files_struct(files);
1511                        return 0;
1512                }
1513                spin_unlock(&files->file_lock);
1514                put_files_struct(files);
1515        }
1516        return -ENOENT;
1517}
1518
1519static int proc_fd_link(struct inode *inode, struct path *path)
1520{
1521        return proc_fd_info(inode, path, NULL);
1522}
1523
1524static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
1525{
1526        struct inode *inode = dentry->d_inode;
1527        struct task_struct *task = get_proc_task(inode);
1528        int fd = proc_fd(inode);
1529        struct files_struct *files;
1530
1531        if (task) {
1532                files = get_files_struct(task);
1533                if (files) {
1534                        rcu_read_lock();
1535                        if (fcheck_files(files, fd)) {
1536                                rcu_read_unlock();
1537                                put_files_struct(files);
1538                                if (task_dumpable(task)) {
1539                                        inode->i_uid = task->euid;
1540                                        inode->i_gid = task->egid;
1541                                } else {
1542                                        inode->i_uid = 0;
1543                                        inode->i_gid = 0;
1544                                }
1545                                inode->i_mode &= ~(S_ISUID | S_ISGID);
1546                                security_task_to_inode(task, inode);
1547                                put_task_struct(task);
1548                                return 1;
1549                        }
1550                        rcu_read_unlock();
1551                        put_files_struct(files);
1552                }
1553                put_task_struct(task);
1554        }
1555        d_drop(dentry);
1556        return 0;
1557}
1558
1559static struct dentry_operations tid_fd_dentry_operations =
1560{
1561        .d_revalidate   = tid_fd_revalidate,
1562        .d_delete       = pid_delete_dentry,
1563};
1564
1565static struct dentry *proc_fd_instantiate(struct inode *dir,
1566        struct dentry *dentry, struct task_struct *task, const void *ptr)
1567{
1568        unsigned fd = *(const unsigned *)ptr;
1569        struct file *file;
1570        struct files_struct *files;
1571        struct inode *inode;
1572        struct proc_inode *ei;
1573        struct dentry *error = ERR_PTR(-ENOENT);
1574
1575        inode = proc_pid_make_inode(dir->i_sb, task);
1576        if (!inode)
1577                goto out;
1578        ei = PROC_I(inode);
1579        ei->fd = fd;
1580        files = get_files_struct(task);
1581        if (!files)
1582                goto out_iput;
1583        inode->i_mode = S_IFLNK;
1584
1585        /*
1586         * We are not taking a ref to the file structure, so we must
1587         * hold ->file_lock.
1588         */
1589        spin_lock(&files->file_lock);
1590        file = fcheck_files(files, fd);
1591        if (!file)
1592                goto out_unlock;
1593        if (file->f_mode & 1)
1594                inode->i_mode |= S_IRUSR | S_IXUSR;
1595        if (file->f_mode & 2)
1596                inode->i_mode |= S_IWUSR | S_IXUSR;
1597        spin_unlock(&files->file_lock);
1598        put_files_struct(files);
1599
1600        inode->i_op = &proc_pid_link_inode_operations;
1601        inode->i_size = 64;
1602        ei->op.proc_get_link = proc_fd_link;
1603        dentry->d_op = &tid_fd_dentry_operations;
1604        d_add(dentry, inode);
1605        /* Close the race of the process dying before we return the dentry */
1606        if (tid_fd_revalidate(dentry, NULL))
1607                error = NULL;
1608
1609 out:
1610        return error;
1611out_unlock:
1612        spin_unlock(&files->file_lock);
1613        put_files_struct(files);
1614out_iput:
1615        iput(inode);
1616        goto out;
1617}
1618
1619static struct dentry *proc_lookupfd_common(struct inode *dir,
1620                                           struct dentry *dentry,
1621                                           instantiate_t instantiate)
1622{
1623        struct task_struct *task = get_proc_task(dir);
1624        unsigned fd = name_to_int(dentry);
1625        struct dentry *result = ERR_PTR(-ENOENT);
1626
1627        if (!task)
1628                goto out_no_task;
1629        if (fd == ~0U)
1630                goto out;
1631
1632        result = instantiate(dir, dentry, task, &fd);
1633out:
1634        put_task_struct(task);
1635out_no_task:
1636        return result;
1637}
1638
1639static int proc_readfd_common(struct file * filp, void * dirent,
1640                              filldir_t filldir, instantiate_t instantiate)
1641{
1642        struct dentry *dentry = filp->f_path.dentry;
1643        struct inode *inode = dentry->d_inode;
1644        struct task_struct *p = get_proc_task(inode);
1645        unsigned int fd, ino;
1646        int retval;
1647        struct files_struct * files;
1648        struct fdtable *fdt;
1649
1650        retval = -ENOENT;
1651        if (!p)
1652                goto out_no_task;
1653        retval = 0;
1654
1655        fd = filp->f_pos;
1656        switch (fd) {
1657                case 0:
1658                        if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
1659                                goto out;
1660                        filp->f_pos++;
1661                case 1:
1662                        ino = parent_ino(dentry);
1663                        if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
1664                                goto out;
1665                        filp->f_pos++;
1666                default:
1667                        files = get_files_struct(p);
1668                        if (!files)
1669                                goto out;
1670                        rcu_read_lock();
1671                        fdt = files_fdtable(files);
1672                        for (fd = filp->f_pos-2;
1673                             fd < fdt->max_fds;
1674                             fd++, filp->f_pos++) {
1675                                char name[PROC_NUMBUF];
1676                                int len;
1677
1678                                if (!fcheck_files(files, fd))
1679                                        continue;
1680                                rcu_read_unlock();
1681
1682                                len = snprintf(name, sizeof(name), "%d", fd);
1683                                if (proc_fill_cache(filp, dirent, filldir,
1684                                                    name, len, instantiate,
1685                                                    p, &fd) < 0) {
1686                                        rcu_read_lock();
1687                                        break;
1688                                }
1689                                rcu_read_lock();
1690                        }
1691                        rcu_read_unlock();
1692                        put_files_struct(files);
1693        }
1694out:
1695        put_task_struct(p);
1696out_no_task:
1697        return retval;
1698}
1699
1700static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
1701                                    struct nameidata *nd)
1702{
1703        return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
1704}
1705
1706static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)
1707{
1708        return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);
1709}
1710
1711static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
1712                                      size_t len, loff_t *ppos)
1713{
1714        char tmp[PROC_FDINFO_MAX];
1715        int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, tmp);
1716        if (!err)
1717                err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp));
1718        return err;
1719}
1720
1721static const struct file_operations proc_fdinfo_file_operations = {
1722        .open           = nonseekable_open,
1723        .read           = proc_fdinfo_read,
1724};
1725
1726static const struct file_operations proc_fd_operations = {
1727        .read           = generic_read_dir,
1728        .readdir        = proc_readfd,
1729};
1730
1731/*
1732 * /proc/pid/fd needs a special permission handler so that a process can still
1733 * access /proc/self/fd after it has executed a setuid().
1734 */
1735static int proc_fd_permission(struct inode *inode, int mask,
1736                                struct nameidata *nd)
1737{
1738        int rv;
1739
1740        rv = generic_permission(inode, mask, NULL);
1741        if (rv == 0)
1742                return 0;
1743        if (task_pid(current) == proc_pid(inode))
1744                rv = 0;
1745        return rv;
1746}
1747
1748/*
1749 * proc directories can do almost nothing..
1750 */
1751static const struct inode_operations proc_fd_inode_operations = {
1752        .lookup         = proc_lookupfd,
1753        .permission     = proc_fd_permission,
1754        .setattr        = proc_setattr,
1755};
1756
1757static struct dentry *proc_fdinfo_instantiate(struct inode *dir,
1758        struct dentry *dentry, struct task_struct *task, const void *ptr)
1759{
1760        unsigned fd = *(unsigned *)ptr;
1761        struct inode *inode;
1762        struct proc_inode *ei;
1763        struct dentry *error = ERR_PTR(-ENOENT);
1764
1765        inode = proc_pid_make_inode(dir->i_sb, task);
1766        if (!inode)
1767                goto out;
1768        ei = PROC_I(inode);
1769        ei->fd = fd;
1770        inode->i_mode = S_IFREG | S_IRUSR;
1771        inode->i_fop = &proc_fdinfo_file_operations;
1772        dentry->d_op = &tid_fd_dentry_operations;
1773        d_add(dentry, inode);
1774        /* Close the race of the process dying before we return the dentry */
1775        if (tid_fd_revalidate(dentry, NULL))
1776                error = NULL;
1777
1778 out:
1779        return error;
1780}
1781
1782static struct dentry *proc_lookupfdinfo(struct inode *dir,
1783                                        struct dentry *dentry,
1784                                        struct nameidata *nd)
1785{
1786        return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
1787}
1788
1789static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir)
1790{
1791        return proc_readfd_common(filp, dirent, filldir,
1792                                  proc_fdinfo_instantiate);
1793}
1794
1795static const struct file_operations proc_fdinfo_operations = {
1796        .read           = generic_read_dir,
1797        .readdir        = proc_readfdinfo,
1798};
1799
1800/*
1801 * proc directories can do almost nothing..
1802 */
1803static const struct inode_operations proc_fdinfo_inode_operations = {
1804        .lookup         = proc_lookupfdinfo,
1805        .setattr        = proc_setattr,
1806};
1807
1808
1809static struct dentry *proc_pident_instantiate(struct inode *dir,
1810        struct dentry *dentry, struct task_struct *task, const void *ptr)
1811{
1812        const struct pid_entry *p = ptr;
1813        struct inode *inode;
1814        struct proc_inode *ei;
1815        struct dentry *error = ERR_PTR(-EINVAL);
1816
1817        inode = proc_pid_make_inode(dir->i_sb, task);
1818        if (!inode)
1819                goto out;
1820
1821        ei = PROC_I(inode);
1822        inode->i_mode = p->mode;
1823        if (S_ISDIR(inode->i_mode))
1824                inode->i_nlink = 2;     /* Use getattr to fix if necessary */
1825        if (p->iop)
1826                inode->i_op = p->iop;
1827        if (p->fop)
1828                inode->i_fop = p->fop;
1829        ei->op = p->op;
1830        dentry->d_op = &pid_dentry_operations;
1831        d_add(dentry, inode);
1832        /* Close the race of the process dying before we return the dentry */
1833        if (pid_revalidate(dentry, NULL))
1834                error = NULL;
1835out:
1836        return error;
1837}
1838
1839static struct dentry *proc_pident_lookup(struct inode *dir, 
1840                                         struct dentry *dentry,
1841                                         const struct pid_entry *ents,
1842                                         unsigned int nents)
1843{
1844        struct inode *inode;
1845        struct dentry *error;
1846        struct task_struct *task = get_proc_task(dir);
1847        const struct pid_entry *p, *last;
1848
1849        error = ERR_PTR(-ENOENT);
1850        inode = NULL;
1851
1852        if (!task)
1853                goto out_no_task;
1854
1855        /*
1856         * Yes, it does not scale. And it should not. Don't add
1857         * new entries into /proc/<tgid>/ without very good reasons.
1858         */
1859        last = &ents[nents - 1];
1860        for (p = ents; p <= last; p++) {
1861                if (p->len != dentry->d_name.len)
1862                        continue;
1863                if (!memcmp(dentry->d_name.name, p->name, p->len))
1864                        break;
1865        }
1866        if (p > last)
1867                goto out;
1868
1869        error = proc_pident_instantiate(dir, dentry, task, p);
1870out:
1871        put_task_struct(task);
1872out_no_task:
1873        return error;
1874}
1875
1876static int proc_pident_fill_cache(struct file *filp, void *dirent,
1877        filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
1878{
1879        return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
1880                                proc_pident_instantiate, task, p);
1881}
1882
1883static int proc_pident_readdir(struct file *filp,
1884                void *dirent, filldir_t filldir,
1885                const struct pid_entry *ents, unsigned int nents)
1886{
1887        int i;
1888        struct dentry *dentry = filp->f_path.dentry;
1889        struct inode *inode = dentry->d_inode;
1890        struct task_struct *task = get_proc_task(inode);
1891        const struct pid_entry *p, *last;
1892        ino_t ino;
1893        int ret;
1894
1895        ret = -ENOENT;
1896        if (!task)
1897                goto out_no_task;
1898
1899        ret = 0;
1900        i = filp->f_pos;
1901        switch (i) {
1902        case 0:
1903                ino = inode->i_ino;
1904                if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1905                        goto out;
1906                i++;
1907                filp->f_pos++;
1908                /* fall through */
1909        case 1:
1910                ino = parent_ino(dentry);
1911                if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1912                        goto out;
1913                i++;
1914                filp->f_pos++;
1915                /* fall through */
1916        default:
1917                i -= 2;
1918                if (i >= nents) {
1919                        ret = 1;
1920                        goto out;
1921                }
1922                p = ents + i;
1923                last = &ents[nents - 1];
1924                while (p <= last) {
1925                        if (proc_pident_fill_cache(filp, dirent, filldir, task, p) < 0)
1926                                goto out;
1927                        filp->f_pos++;
1928                        p++;
1929                }
1930        }
1931
1932        ret = 1;
1933out:
1934        put_task_struct(task);
1935out_no_task:
1936        return ret;
1937}
1938
1939#ifdef CONFIG_SECURITY
1940static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
1941                                  size_t count, loff_t *ppos)
1942{
1943        struct inode * inode = file->f_path.dentry->d_inode;
1944        char *p = NULL;
1945        ssize_t length;
1946        struct task_struct *task = get_proc_task(inode);
1947
1948        if (!task)
1949                return -ESRCH;
1950
1951        length = security_getprocattr(task,
1952                                      (char*)file->f_path.dentry->d_name.name,
1953                                      &p);
1954        put_task_struct(task);
1955        if (length > 0)
1956                length = simple_read_from_buffer(buf, count, ppos, p, length);
1957        kfree(p);
1958        return length;
1959}
1960
1961static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
1962                                   size_t count, loff_t *ppos)
1963{
1964        struct inode * inode = file->f_path.dentry->d_inode;
1965        char *page;
1966        ssize_t length;
1967        struct task_struct *task = get_proc_task(inode);
1968
1969        length = -ESRCH;
1970        if (!task)
1971                goto out_no_task;
1972        if (count > PAGE_SIZE)
1973                count = PAGE_SIZE;
1974
1975        /* No partial writes. */
1976        length = -EINVAL;
1977        if (*ppos != 0)
1978                goto out;
1979
1980        length = -ENOMEM;
1981        page = (char*)__get_free_page(GFP_TEMPORARY);
1982        if (!page)
1983                goto out;
1984
1985        length = -EFAULT;
1986        if (copy_from_user(page, buf, count))
1987                goto out_free;
1988
1989        length = security_setprocattr(task,
1990                                      (char*)file->f_path.dentry->d_name.name,
1991                                      (void*)page, count);
1992out_free:
1993        free_page((unsigned long) page);
1994out:
1995        put_task_struct(task);
1996out_no_task:
1997        return length;
1998}
1999
2000static const struct file_operations proc_pid_attr_operations = {
2001        .read           = proc_pid_attr_read,
2002        .write          = proc_pid_attr_write,
2003};
2004
2005static const struct pid_entry attr_dir_stuff[] = {
2006        REG("current",    S_IRUGO|S_IWUGO, pid_attr),
2007        REG("prev",       S_IRUGO,         pid_attr),
2008        REG("exec",       S_IRUGO|S_IWUGO, pid_attr),
2009        REG("fscreate",   S_IRUGO|S_IWUGO, pid_attr),
2010        REG("keycreate",  S_IRUGO|S_IWUGO, pid_attr),
2011        REG("sockcreate", S_IRUGO|S_IWUGO, pid_attr),
2012};
2013
2014static int proc_attr_dir_readdir(struct file * filp,
2015                             void * dirent, filldir_t filldir)
2016{
2017        return proc_pident_readdir(filp,dirent,filldir,
2018                                   attr_dir_stuff,ARRAY_SIZE(attr_dir_stuff));
2019}
2020
2021static const struct file_operations proc_attr_dir_operations = {
2022        .read           = generic_read_dir,
2023        .readdir        = proc_attr_dir_readdir,
2024};
2025
2026static struct dentry *proc_attr_dir_lookup(struct inode *dir,
2027                                struct dentry *dentry, struct nameidata *nd)
2028{
2029        return proc_pident_lookup(dir, dentry,
2030                                  attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2031}
2032
2033static const struct inode_operations proc_attr_dir_inode_operations = {
2034        .lookup         = proc_attr_dir_lookup,
2035        .getattr        = pid_getattr,
2036        .setattr        = proc_setattr,
2037};
2038
2039#endif
2040
2041#if defined(USE_ELF_CORE_DUMP) && defined(CONFIG_ELF_CORE)
2042static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
2043                                         size_t count, loff_t *ppos)
2044{
2045        struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
2046        struct mm_struct *mm;
2047        char buffer[PROC_NUMBUF];
2048        size_t len;
2049        int ret;
2050
2051        if (!task)
2052                return -ESRCH;
2053
2054        ret = 0;
2055        mm = get_task_mm(task);
2056        if (mm) {
2057                len = snprintf(buffer, sizeof(buffer), "%08lx\n",
2058                               ((mm->flags & MMF_DUMP_FILTER_MASK) >>
2059                                MMF_DUMP_FILTER_SHIFT));
2060                mmput(mm);
2061                ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
2062        }
2063
2064        put_task_struct(task);
2065
2066        return ret;
2067}
2068
2069static ssize_t proc_coredump_filter_write(struct file *file,
2070                                          const char __user *buf,
2071                                          size_t count,
2072                                          loff_t *ppos)
2073{
2074        struct task_struct *task;
2075        struct mm_struct *mm;
2076        char buffer[PROC_NUMBUF], *end;
2077        unsigned int val;
2078        int ret;
2079        int i;
2080        unsigned long mask;
2081
2082        ret = -EFAULT;
2083        memset(buffer, 0, sizeof(buffer));
2084        if (count > sizeof(buffer) - 1)
2085                count = sizeof(buffer) - 1;
2086        if (copy_from_user(buffer, buf, count))
2087                goto out_no_task;
2088
2089        ret = -EINVAL;
2090        val = (unsigned int)simple_strtoul(buffer, &end, 0);
2091        if (*end == '\n')
2092                end++;
2093        if (end - buffer == 0)
2094                goto out_no_task;
2095
2096        ret = -ESRCH;
2097        task = get_proc_task(file->f_dentry->d_inode);
2098        if (!task)
2099                goto out_no_task;
2100
2101        ret = end - buffer;
2102        mm = get_task_mm(task);
2103        if (!mm)
2104                goto out_no_mm;
2105
2106        for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
2107                if (val & mask)
2108                        set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2109                else
2110                        clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2111        }
2112
2113        mmput(mm);
2114 out_no_mm:
2115        put_task_struct(task);
2116 out_no_task:
2117        return ret;
2118}
2119
2120static const struct file_operations proc_coredump_filter_operations = {
2121        .read           = proc_coredump_filter_read,
2122        .write          = proc_coredump_filter_write,
2123};
2124#endif
2125
2126/*
2127 * /proc/self:
2128 */
2129static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
2130                              int buflen)
2131{
2132        struct pid_namespace *ns = dentry->d_sb->s_fs_info;
2133        pid_t tgid = task_tgid_nr_ns(current, ns);
2134        char tmp[PROC_NUMBUF];
2135        if (!tgid)
2136                return -ENOENT;
2137        sprintf(tmp, "%d", tgid);
2138        return vfs_readlink(dentry,buffer,buflen,tmp);
2139}
2140
2141static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
2142{
2143        struct pid_namespace *ns = dentry->d_sb->s_fs_info;
2144        pid_t tgid = task_tgid_nr_ns(current, ns);
2145        char tmp[PROC_NUMBUF];
2146        if (!tgid)
2147                return ERR_PTR(-ENOENT);
2148        sprintf(tmp, "%d", task_tgid_nr_ns(current, ns));
2149        return ERR_PTR(vfs_follow_link(nd,tmp));
2150}
2151
2152static const struct inode_operations proc_self_inode_operations = {
2153        .readlink       = proc_self_readlink,
2154        .follow_link    = proc_self_follow_link,
2155};
2156
2157/*
2158 * proc base
2159 *
2160 * These are the directory entries in the root directory of /proc
2161 * that properly belong to the /proc filesystem, as they describe
2162 * describe something that is process related.
2163 */
2164static const struct pid_entry proc_base_stuff[] = {
2165        NOD("self", S_IFLNK|S_IRWXUGO,
2166                &proc_self_inode_operations, NULL, {}),
2167};
2168
2169/*
2170 *      Exceptional case: normally we are not allowed to unhash a busy
2171 * directory. In this case, however, we can do it - no aliasing problems
2172 * due to the way we treat inodes.
2173 */
2174static int proc_base_revalidate(struct dentry *dentry, struct nameidata *nd)
2175{
2176        struct inode *inode = dentry->d_inode;
2177        struct task_struct *task = get_proc_task(inode);
2178        if (task) {
2179                put_task_struct(task);
2180                return 1;
2181        }
2182        d_drop(dentry);
2183        return 0;
2184}
2185
2186static struct dentry_operations proc_base_dentry_operations =
2187{
2188        .d_revalidate   = proc_base_revalidate,
2189        .d_delete       = pid_delete_dentry,
2190};
2191
2192static struct dentry *proc_base_instantiate(struct inode *dir,
2193        struct dentry *dentry, struct task_struct *task, const void *ptr)
2194{
2195        const struct pid_entry *p = ptr;
2196        struct inode *inode;
2197        struct proc_inode *ei;
2198        struct dentry *error = ERR_PTR(-EINVAL);
2199
2200        /* Allocate the inode */
2201        error = ERR_PTR(-ENOMEM);
2202        inode = new_inode(dir->i_sb);
2203        if (!inode)
2204                goto out;
2205
2206        /* Initialize the inode */
2207        ei = PROC_I(inode);
2208        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
2209
2210        /*
2211         * grab the reference to the task.
2212         */
2213        ei->pid = get_task_pid(task, PIDTYPE_PID);
2214        if (!ei->pid)
2215                goto out_iput;
2216
2217        inode->i_uid = 0;
2218        inode->i_gid = 0;
2219        inode->i_mode = p->mode;
2220        if (S_ISDIR(inode->i_mode))
2221                inode->i_nlink = 2;
2222        if (S_ISLNK(inode->i_mode))
2223                inode->i_size = 64;
2224        if (p->iop)
2225                inode->i_op = p->iop;
2226        if (p->fop)
2227                inode->i_fop = p->fop;
2228        ei->op = p->op;
2229        dentry->d_op = &proc_base_dentry_operations;
2230        d_add(dentry, inode);
2231        error = NULL;
2232out:
2233        return error;
2234out_iput:
2235        iput(inode);
2236        goto out;
2237}
2238
2239static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
2240{
2241        struct dentry *error;
2242        struct task_struct *task = get_proc_task(dir);
2243        const struct pid_entry *p, *last;
2244
2245        error = ERR_PTR(-ENOENT);
2246
2247        if (!task)
2248                goto out_no_task;
2249
2250        /* Lookup the directory entry */
2251        last = &proc_base_stuff[ARRAY_SIZE(proc_base_stuff) - 1];
2252        for (p = proc_base_stuff; p <= last; p++) {
2253                if (p->len != dentry->d_name.len)
2254                        continue;
2255                if (!memcmp(dentry->d_name.name, p->name, p->len))
2256                        break;
2257        }
2258        if (p > last)
2259                goto out;
2260
2261        error = proc_base_instantiate(dir, dentry, task, p);
2262
2263out:
2264        put_task_struct(task);
2265out_no_task:
2266        return error;
2267}
2268
2269static int proc_base_fill_cache(struct file *filp, void *dirent,
2270        filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
2271{
2272        return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
2273                                proc_base_instantiate, task, p);
2274}
2275
2276#ifdef CONFIG_TASK_IO_ACCOUNTING
2277static int proc_pid_io_accounting(struct task_struct *task, char *buffer)
2278{
2279        return sprintf(buffer,
2280#ifdef CONFIG_TASK_XACCT
2281                        "rchar: %llu\n"
2282                        "wchar: %llu\n"
2283                        "syscr: %llu\n"
2284                        "syscw: %llu\n"
2285#endif
2286                        "read_bytes: %llu\n"
2287                        "write_bytes: %llu\n"
2288                        "cancelled_write_bytes: %llu\n",
2289#ifdef CONFIG_TASK_XACCT
2290                        (unsigned long long)task->rchar,
2291                        (unsigned long long)task->wchar,
2292                        (unsigned long long)task->syscr,
2293                        (unsigned long long)task->syscw,
2294#endif
2295                        (unsigned long long)task->ioac.read_bytes,
2296                        (unsigned long long)task->ioac.write_bytes,
2297                        (unsigned long long)task->ioac.cancelled_write_bytes);
2298}
2299#endif
2300
2301/*
2302 * Thread groups
2303 */
2304static const struct file_operations proc_task_operations;
2305static const struct inode_operations proc_task_inode_operations;
2306
2307static const struct pid_entry tgid_base_stuff[] = {
2308        DIR("task",       S_IRUGO|S_IXUGO, task),
2309        DIR("fd",         S_IRUSR|S_IXUSR, fd),
2310        DIR("fdinfo",     S_IRUSR|S_IXUSR, fdinfo),
2311#ifdef CONFIG_NET
2312        DIR("net",        S_IRUGO|S_IXUGO, net),
2313#endif
2314        REG("environ",    S_IRUSR, environ),
2315        INF("auxv",       S_IRUSR, pid_auxv),
2316        ONE("status",     S_IRUGO, pid_status),
2317        INF("limits",     S_IRUSR, pid_limits),
2318#ifdef CONFIG_SCHED_DEBUG
2319        REG("sched",      S_IRUGO|S_IWUSR, pid_sched),
2320#endif
2321        INF("cmdline",    S_IRUGO, pid_cmdline),
2322        ONE("stat",       S_IRUGO, tgid_stat),
2323        ONE("statm",      S_IRUGO, pid_statm),
2324        REG("maps",       S_IRUGO, maps),
2325#ifdef CONFIG_NUMA
2326        REG("numa_maps",  S_IRUGO, numa_maps),
2327#endif
2328        REG("mem",        S_IRUSR|S_IWUSR, mem),
2329        LNK("cwd",        cwd),
2330        LNK("root",       root),
2331        LNK("exe",        exe),
2332        REG("mounts",     S_IRUGO, mounts),
2333        REG("mountstats", S_IRUSR, mountstats),
2334#ifdef CONFIG_PROC_PAGE_MONITOR
2335        REG("clear_refs", S_IWUSR, clear_refs),
2336        REG("smaps",      S_IRUGO, smaps),
2337        REG("pagemap",    S_IRUSR, pagemap),
2338#endif
2339#ifdef CONFIG_SECURITY
2340        DIR("attr",       S_IRUGO|S_IXUGO, attr_dir),
2341#endif
2342#ifdef CONFIG_KALLSYMS
2343        INF("wchan",      S_IRUGO, pid_wchan),
2344#endif
2345#ifdef CONFIG_SCHEDSTATS
2346        INF("schedstat",  S_IRUGO, pid_schedstat),
2347#endif
2348#ifdef CONFIG_LATENCYTOP
2349        REG("latency",  S_IRUGO, lstats),
2350#endif
2351#ifdef CONFIG_PROC_PID_CPUSET
2352        REG("cpuset",     S_IRUGO, cpuset),
2353#endif
2354#ifdef CONFIG_CGROUPS
2355        REG("cgroup",  S_IRUGO, cgroup),
2356#endif
2357        INF("oom_score",  S_IRUGO, oom_score),
2358        REG("oom_adj",    S_IRUGO|S_IWUSR, oom_adjust),
2359#ifdef CONFIG_AUDITSYSCALL
2360        REG("loginuid",   S_IWUSR|S_IRUGO, loginuid),
2361        REG("sessionid",  S_IRUSR, sessionid),
2362#endif
2363#ifdef CONFIG_FAULT_INJECTION
2364        REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),
2365#endif
2366#if defined(USE_ELF_CORE_DUMP) && defined(CONFIG_ELF_CORE)
2367        REG("coredump_filter", S_IRUGO|S_IWUSR, coredump_filter),
2368#endif
2369#ifdef CONFIG_TASK_IO_ACCOUNTING
2370        INF("io",       S_IRUGO, pid_io_accounting),
2371#endif
2372};
2373
2374static int proc_tgid_base_readdir(struct file * filp,
2375                             void * dirent, filldir_t filldir)
2376{
2377        return proc_pident_readdir(filp,dirent,filldir,
2378                                   tgid_base_stuff,ARRAY_SIZE(tgid_base_stuff));
2379}
2380
2381static const struct file_operations proc_tgid_base_operations = {
2382        .read           = generic_read_dir,
2383        .readdir        = proc_tgid_base_readdir,
2384};
2385
2386static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
2387        return proc_pident_lookup(dir, dentry,
2388                                  tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2389}
2390
2391static const struct inode_operations proc_tgid_base_inode_operations = {
2392        .lookup         = proc_tgid_base_lookup,
2393        .getattr        = pid_getattr,
2394        .setattr        = proc_setattr,
2395};
2396
2397static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
2398{
2399        struct dentry *dentry, *leader, *dir;
2400        char buf[PROC_NUMBUF];
2401        struct qstr name;
2402
2403        name.name = buf;
2404        name.len = snprintf(buf, sizeof(buf), "%d", pid);
2405        dentry = d_hash_and_lookup(mnt->mnt_root, &name);
2406        if (dentry) {
2407                if (!(current->flags & PF_EXITING))
2408                        shrink_dcache_parent(dentry);
2409                d_drop(dentry);
2410                dput(dentry);
2411        }
2412
2413        if (tgid == 0)
2414                goto out;
2415
2416        name.name = buf;
2417        name.len = snprintf(buf, sizeof(buf), "%d", tgid);
2418        leader = d_hash_and_lookup(mnt->mnt_root, &name);
2419        if (!leader)
2420                goto out;
2421
2422        name.name = "task";
2423        name.len = strlen(name.name);
2424        dir = d_hash_and_lookup(leader, &name);
2425        if (!dir)
2426                goto out_put_leader;
2427
2428        name.name = buf;
2429        name.len = snprintf(buf, sizeof(buf), "%d", pid);
2430        dentry = d_hash_and_lookup(dir, &name);
2431        if (dentry) {
2432                shrink_dcache_parent(dentry);
2433                d_drop(dentry);
2434                dput(dentry);
2435        }
2436
2437        dput(dir);
2438out_put_leader:
2439        dput(leader);
2440out:
2441        return;
2442}
2443
2444/**
2445 * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
2446 * @task: task that should be flushed.
2447 *
2448 * When flushing dentries from proc, one needs to flush them from global
2449 * proc (proc_mnt) and from all the namespaces' procs this task was seen
2450 * in. This call is supposed to do all of this job.
2451 *
2452 * Looks in the dcache for
2453 * /proc/@pid
2454 * /proc/@tgid/task/@pid
2455 * if either directory is present flushes it and all of it'ts children
2456 * from the dcache.
2457 *
2458 * It is safe and reasonable to cache /proc entries for a task until
2459 * that task exits.  After that they just clog up the dcache with
2460 * useless entries, possibly causing useful dcache entries to be
2461 * flushed instead.  This routine is proved to flush those useless
2462 * dcache entries at process exit time.
2463 *
2464 * NOTE: This routine is just an optimization so it does not guarantee
2465 *       that no dcache entries will exist at process exit time it
2466 *       just makes it very unlikely that any will persist.
2467 */
2468
2469void proc_flush_task(struct task_struct *task)
2470{
2471        int i;
2472        struct pid *pid, *tgid = NULL;
2473        struct upid *upid;
2474
2475        pid = task_pid(task);
2476        if (thread_group_leader(task))
2477                tgid = task_tgid(task);
2478
2479        for (i = 0; i <= pid->level; i++) {
2480                upid = &pid->numbers[i];
2481                proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
2482                        tgid ? tgid->numbers[i].nr : 0);
2483        }
2484
2485        upid = &pid->numbers[pid->level];
2486        if (upid->nr == 1)
2487                pid_ns_release_proc(upid->ns);
2488}
2489
2490static struct dentry *proc_pid_instantiate(struct inode *dir,
2491                                           struct dentry * dentry,
2492                                           struct task_struct *task, const void *ptr)
2493{
2494        struct dentry *error = ERR_PTR(-ENOENT);
2495        struct inode *inode;
2496
2497        inode = proc_pid_make_inode(dir->i_sb, task);
2498        if (!inode)
2499                goto out;
2500
2501        inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
2502        inode->i_op = &proc_tgid_base_inode_operations;
2503        inode->i_fop = &proc_tgid_base_operations;
2504        inode->i_flags|=S_IMMUTABLE;
2505
2506        inode->i_nlink = 2 + pid_entry_count_dirs(tgid_base_stuff,
2507                ARRAY_SIZE(tgid_base_stuff));
2508
2509        dentry->d_op = &pid_dentry_operations;
2510
2511        d_add(dentry, inode);
2512        /* Close the race of the process dying before we return the dentry */
2513        if (pid_revalidate(dentry, NULL))
2514                error = NULL;
2515out:
2516        return error;
2517}
2518
2519struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
2520{
2521        struct dentry *result = ERR_PTR(-ENOENT);
2522        struct task_struct *task;
2523        unsigned tgid;
2524        struct pid_namespace *ns;
2525
2526        result = proc_base_lookup(dir, dentry);
2527        if (!IS_ERR(result) || PTR_ERR(result) != -ENOENT)
2528                goto out;
2529
2530        tgid = name_to_int(dentry);
2531        if (tgid == ~0U)
2532                goto out;
2533
2534        ns = dentry->d_sb->s_fs_info;
2535        rcu_read_lock();
2536        task = find_task_by_pid_ns(tgid, ns);
2537        if (task)
2538                get_task_struct(task);
2539        rcu_read_unlock();
2540        if (!task)
2541                goto out;
2542
2543        result = proc_pid_instantiate(dir, dentry, task, NULL);
2544        put_task_struct(task);
2545out:
2546        return result;
2547}
2548
2549/*
2550 * Find the first task with tgid >= tgid
2551 *
2552 */
2553struct tgid_iter {
2554        unsigned int tgid;
2555        struct task_struct *task;
2556};
2557static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter)
2558{
2559        struct pid *pid;
2560
2561        if (iter.task)
2562                put_task_struct(iter.task);
2563        rcu_read_lock();
2564retry:
2565        iter.task = NULL;
2566        pid = find_ge_pid(iter.tgid, ns);
2567        if (pid) {
2568                iter.tgid = pid_nr_ns(pid, ns);
2569                iter.task = pid_task(pid, PIDTYPE_PID);
2570                /* What we to know is if the pid we have find is the
2571                 * pid of a thread_group_leader.  Testing for task
2572                 * being a thread_group_leader is the obvious thing
2573                 * todo but there is a window when it fails, due to
2574                 * the pid transfer logic in de_thread.
2575                 *
2576                 * So we perform the straight forward test of seeing
2577                 * if the pid we have found is the pid of a thread
2578                 * group leader, and don't worry if the task we have
2579                 * found doesn't happen to be a thread group leader.
2580                 * As we don't care in the case of readdir.
2581                 */
2582                if (!iter.task || !has_group_leader_pid(iter.task)) {
2583                        iter.tgid += 1;
2584                        goto retry;
2585                }
2586                get_task_struct(iter.task);
2587        }
2588        rcu_read_unlock();
2589        return iter;
2590}
2591
2592#define TGID_OFFSET (FIRST_PROCESS_ENTRY + ARRAY_SIZE(proc_base_stuff))
2593
2594static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
2595        struct tgid_iter iter)
2596{
2597        char name[PROC_NUMBUF];
2598        int len = snprintf(name, sizeof(name), "%d", iter.tgid);
2599        return proc_fill_cache(filp, dirent, filldir, name, len,
2600                                proc_pid_instantiate, iter.task, NULL);
2601}
2602
2603/* for the /proc/ directory itself, after non-process stuff has been done */
2604int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
2605{
2606        unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
2607        struct task_struct *reaper = get_proc_task(filp->f_path.dentry->d_inode);
2608        struct tgid_iter iter;
2609        struct pid_namespace *ns;
2610
2611        if (!reaper)
2612                goto out_no_task;
2613
2614        for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) {
2615                const struct pid_entry *p = &proc_base_stuff[nr];
2616                if (proc_base_fill_cache(filp, dirent, filldir, reaper, p) < 0)
2617                        goto out;
2618        }
2619
2620        ns = filp->f_dentry->d_sb->s_fs_info;
2621        iter.task = NULL;
2622        iter.tgid = filp->f_pos - TGID_OFFSET;
2623        for (iter = next_tgid(ns, iter);
2624             iter.task;
2625             iter.tgid += 1, iter = next_tgid(ns, iter)) {
2626                filp->f_pos = iter.tgid + TGID_OFFSET;
2627                if (proc_pid_fill_cache(filp, dirent, filldir, iter) < 0) {
2628                        put_task_struct(iter.task);
2629                        goto out;
2630                }
2631        }
2632        filp->f_pos = PID_MAX_LIMIT + TGID_OFFSET;
2633out:
2634        put_task_struct(reaper);
2635out_no_task:
2636        return 0;
2637}
2638
2639/*
2640 * Tasks
2641 */
2642static const struct pid_entry tid_base_stuff[] = {
2643        DIR("fd",        S_IRUSR|S_IXUSR, fd),
2644        DIR("fdinfo",    S_IRUSR|S_IXUSR, fdinfo),
2645        REG("environ",   S_IRUSR, environ),
2646        INF("auxv",      S_IRUSR, pid_auxv),
2647        ONE("status",    S_IRUGO, pid_status),
2648        INF("limits",    S_IRUSR, pid_limits),
2649#ifdef CONFIG_SCHED_DEBUG
2650        REG("sched",     S_IRUGO|S_IWUSR, pid_sched),
2651#endif
2652        INF("cmdline",   S_IRUGO, pid_cmdline),
2653        ONE("stat",      S_IRUGO, tid_stat),
2654        ONE("statm",     S_IRUGO, pid_statm),
2655        REG("maps",      S_IRUGO, maps),
2656#ifdef CONFIG_NUMA
2657        REG("numa_maps", S_IRUGO, numa_maps),
2658#endif
2659        REG("mem",       S_IRUSR|S_IWUSR, mem),
2660        LNK("cwd",       cwd),
2661        LNK("root",      root),
2662        LNK("exe",       exe),
2663        REG("mounts",    S_IRUGO, mounts),
2664#ifdef CONFIG_PROC_PAGE_MONITOR
2665        REG("clear_refs", S_IWUSR, clear_refs),
2666        REG("smaps",     S_IRUGO, smaps),
2667        REG("pagemap",    S_IRUSR, pagemap),
2668#endif
2669#ifdef CONFIG_SECURITY
2670        DIR("attr",      S_IRUGO|S_IXUGO, attr_dir),
2671#endif
2672#ifdef CONFIG_KALLSYMS
2673        INF("wchan",     S_IRUGO, pid_wchan),
2674#endif
2675#ifdef CONFIG_SCHEDSTATS
2676        INF("schedstat", S_IRUGO, pid_schedstat),
2677#endif
2678#ifdef CONFIG_LATENCYTOP
2679        REG("latency",  S_IRUGO, lstats),
2680#endif
2681#ifdef CONFIG_PROC_PID_CPUSET
2682        REG("cpuset",    S_IRUGO, cpuset),
2683#endif
2684#ifdef CONFIG_CGROUPS
2685        REG("cgroup",  S_IRUGO, cgroup),
2686#endif
2687        INF("oom_score", S_IRUGO, oom_score),
2688        REG("oom_adj",   S_IRUGO|S_IWUSR, oom_adjust),
2689#ifdef CONFIG_AUDITSYSCALL
2690        REG("loginuid",  S_IWUSR|S_IRUGO, loginuid),
2691        REG("sessionid",  S_IRUSR, sessionid),
2692#endif
2693#ifdef CONFIG_FAULT_INJECTION
2694        REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),
2695#endif
2696};
2697
2698static int proc_tid_base_readdir(struct file * filp,
2699                             void * dirent, filldir_t filldir)
2700{
2701        return proc_pident_readdir(filp,dirent,filldir,
2702                                   tid_base_stuff,ARRAY_SIZE(tid_base_stuff));
2703}
2704
2705static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
2706        return proc_pident_lookup(dir, dentry,
2707                                  tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
2708}
2709
2710static const struct file_operations proc_tid_base_operations = {
2711        .read           = generic_read_dir,
2712        .readdir        = proc_tid_base_readdir,
2713};
2714
2715static const struct inode_operations proc_tid_base_inode_operations = {
2716        .lookup         = proc_tid_base_lookup,
2717        .getattr        = pid_getattr,
2718        .setattr        = proc_setattr,
2719};
2720
2721static struct dentry *proc_task_instantiate(struct inode *dir,
2722        struct dentry *dentry, struct task_struct *task, const void *ptr)
2723{
2724        struct dentry *error = ERR_PTR(-ENOENT);
2725        struct inode *inode;
2726        inode = proc_pid_make_inode(dir->i_sb, task);
2727
2728        if (!inode)
2729                goto out;
2730        inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
2731        inode->i_op = &proc_tid_base_inode_operations;
2732        inode->i_fop = &proc_tid_base_operations;
2733        inode->i_flags|=S_IMMUTABLE;
2734
2735        inode->i_nlink = 2 + pid_entry_count_dirs(tid_base_stuff,
2736                ARRAY_SIZE(tid_base_stuff));
2737
2738        dentry->d_op = &pid_dentry_operations;
2739
2740        d_add(dentry, inode);
2741        /* Close the race of the process dying before we return the dentry */
2742        if (pid_revalidate(dentry, NULL))
2743                error = NULL;
2744out:
2745        return error;
2746}
2747
2748static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
2749{
2750        struct dentry *result = ERR_PTR(-ENOENT);
2751        struct task_struct *task;
2752        struct task_struct *leader = get_proc_task(dir);
2753        unsigned tid;
2754        struct pid_namespace *ns;
2755
2756        if (!leader)
2757                goto out_no_task;
2758
2759        tid = name_to_int(dentry);
2760        if (tid == ~0U)
2761                goto out;
2762
2763        ns = dentry->d_sb->s_fs_info;
2764        rcu_read_lock();
2765        task = find_task_by_pid_ns(tid, ns);
2766        if (task)
2767                get_task_struct(task);
2768        rcu_read_unlock();
2769        if (!task)
2770                goto out;
2771        if (!same_thread_group(leader, task))
2772                goto out_drop_task;
2773
2774        result = proc_task_instantiate(dir, dentry, task, NULL);
2775out_drop_task:
2776        put_task_struct(task);
2777out:
2778        put_task_struct(leader);
2779out_no_task:
2780        return result;
2781}
2782
2783/*
2784 * Find the first tid of a thread group to return to user space.
2785 *
2786 * Usually this is just the thread group leader, but if the users
2787 * buffer was too small or there was a seek into the middle of the
2788 * directory we have more work todo.
2789 *
2790 * In the case of a short read we start with find_task_by_pid.
2791 *
2792 * In the case of a seek we start with the leader and walk nr
2793 * threads past it.
2794 */
2795static struct task_struct *first_tid(struct task_struct *leader,
2796                int tid, int nr, struct pid_namespace *ns)
2797{
2798        struct task_struct *pos;
2799
2800        rcu_read_lock();
2801        /* Attempt to start with the pid of a thread */
2802        if (tid && (nr > 0)) {
2803                pos = find_task_by_pid_ns(tid, ns);
2804                if (pos && (pos->group_leader == leader))
2805                        goto found;
2806        }
2807
2808        /* If nr exceeds the number of threads there is nothing todo */
2809        pos = NULL;
2810        if (nr && nr >= get_nr_threads(leader))
2811                goto out;
2812
2813        /* If we haven't found our starting place yet start
2814         * with the leader and walk nr threads forward.
2815         */
2816        for (pos = leader; nr > 0; --nr) {
2817                pos = next_thread(pos);
2818                if (pos == leader) {
2819                        pos = NULL;
2820                        goto out;
2821                }
2822        }
2823found:
2824        get_task_struct(pos);
2825out:
2826        rcu_read_unlock();
2827        return pos;
2828}
2829
2830/*
2831 * Find the next thread in the thread list.
2832 * Return NULL if there is an error or no next thread.
2833 *
2834 * The reference to the input task_struct is released.
2835 */
2836static struct task_struct *next_tid(struct task_struct *start)
2837{
2838        struct task_struct *pos = NULL;
2839        rcu_read_lock();
2840        if (pid_alive(start)) {
2841                pos = next_thread(start);
2842                if (thread_group_leader(pos))
2843                        pos = NULL;
2844                else
2845                        get_task_struct(pos);
2846        }
2847        rcu_read_unlock();
2848        put_task_struct(start);
2849        return pos;
2850}
2851
2852static int proc_task_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
2853        struct task_struct *task, int tid)
2854{
2855        char name[PROC_NUMBUF];
2856        int len = snprintf(name, sizeof(name), "%d", tid);
2857        return proc_fill_cache(filp, dirent, filldir, name, len,
2858                                proc_task_instantiate, task, NULL);
2859}
2860
2861/* for the /proc/TGID/task/ directories */
2862static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir)
2863{
2864        struct dentry *dentry = filp->f_path.dentry;
2865        struct inode *inode = dentry->d_inode;
2866        struct task_struct *leader = NULL;
2867        struct task_struct *task;
2868        int retval = -ENOENT;
2869        ino_t ino;
2870        int tid;
2871        unsigned long pos = filp->f_pos;  /* avoiding "long long" filp->f_pos */
2872        struct pid_namespace *ns;
2873
2874        task = get_proc_task(inode);
2875        if (!task)
2876                goto out_no_task;
2877        rcu_read_lock();
2878        if (pid_alive(task)) {
2879                leader = task->group_leader;
2880                get_task_struct(leader);
2881        }
2882        rcu_read_unlock();
2883        put_task_struct(task);
2884        if (!leader)
2885                goto out_no_task;
2886        retval = 0;
2887
2888        switch (pos) {
2889        case 0:
2890                ino = inode->i_ino;
2891                if (filldir(dirent, ".", 1, pos, ino, DT_DIR) < 0)
2892                        goto out;
2893                pos++;
2894                /* fall through */
2895        case 1:
2896                ino = parent_ino(dentry);
2897                if (filldir(dirent, "..", 2, pos, ino, DT_DIR) < 0)
2898                        goto out;
2899                pos++;
2900                /* fall through */
2901        }
2902
2903        /* f_version caches the tgid value that the last readdir call couldn't
2904         * return. lseek aka telldir automagically resets f_version to 0.
2905         */
2906        ns = filp->f_dentry->d_sb->s_fs_info;
2907        tid = (int)filp->f_version;
2908        filp->f_version = 0;
2909        for (task = first_tid(leader, tid, pos - 2, ns);
2910             task;
2911             task = next_tid(task), pos++) {
2912                tid = task_pid_nr_ns(task, ns);
2913                if (proc_task_fill_cache(filp, dirent, filldir, task, tid) < 0) {
2914                        /* returning this tgid failed, save it as the first
2915                         * pid for the next readir call */
2916                        filp->f_version = (u64)tid;
2917                        put_task_struct(task);
2918                        break;
2919                }
2920        }
2921out:
2922        filp->f_pos = pos;
2923        put_task_struct(leader);
2924out_no_task:
2925        return retval;
2926}
2927
2928static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
2929{
2930        struct inode *inode = dentry->d_inode;
2931        struct task_struct *p = get_proc_task(inode);
2932        generic_fillattr(inode, stat);
2933
2934        if (p) {
2935                rcu_read_lock();
2936                stat->nlink += get_nr_threads(p);
2937                rcu_read_unlock();
2938                put_task_struct(p);
2939        }
2940
2941        return 0;
2942}
2943
2944static const struct inode_operations proc_task_inode_operations = {
2945        .lookup         = proc_task_lookup,
2946        .getattr        = proc_task_getattr,
2947        .setattr        = proc_setattr,
2948};
2949
2950static const struct file_operations proc_task_operations = {
2951        .read           = generic_read_dir,
2952        .readdir        = proc_task_readdir,
2953};
2954
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