LXR linux/fs/proc/inode.c

   1/*
   2 *  linux/fs/proc/inode.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 */
   6
   7#include <linux/time.h>
   8#include <linux/proc_fs.h>
   9#include <linux/kernel.h>
  10#include <linux/pid_namespace.h>
  11#include <linux/mm.h>
  12#include <linux/string.h>
  13#include <linux/stat.h>
  14#include <linux/completion.h>
  15#include <linux/poll.h>
  16#include <linux/printk.h>
  17#include <linux/file.h>
  18#include <linux/limits.h>
  19#include <linux/init.h>
  20#include <linux/module.h>
  21#include <linux/sysctl.h>
  22#include <linux/seq_file.h>
  23#include <linux/slab.h>
  24#include <linux/mount.h>
  25#include <linux/magic.h>
  26
  27#include <asm/uaccess.h>
  28
  29#include "internal.h"
  30
  31static void proc_evict_inode(struct inode *inode)
  32{
  33        struct proc_dir_entry *de;
  34        struct ctl_table_header *head;
  35        const struct proc_ns_operations *ns_ops;
  36        void *ns;
  37
  38        truncate_inode_pages(&inode->i_data, 0);
  39        clear_inode(inode);
  40
  41        /* Stop tracking associated processes */
  42        put_pid(PROC_I(inode)->pid);
  43
  44        /* Let go of any associated proc directory entry */
  45        de = PROC_I(inode)->pde;
  46        if (de)
  47                pde_put(de);
  48        head = PROC_I(inode)->sysctl;
  49        if (head) {
  50                rcu_assign_pointer(PROC_I(inode)->sysctl, NULL);
  51                sysctl_head_put(head);
  52        }
  53        /* Release any associated namespace */
  54        ns_ops = PROC_I(inode)->ns.ns_ops;
  55        ns = PROC_I(inode)->ns.ns;
  56        if (ns_ops && ns)
  57                ns_ops->put(ns);
  58}
  59
  60static struct kmem_cache * proc_inode_cachep;
  61
  62static struct inode *proc_alloc_inode(struct super_block *sb)
  63{
  64        struct proc_inode *ei;
  65        struct inode *inode;
  66
  67        ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
  68        if (!ei)
  69                return NULL;
  70        ei->pid = NULL;
  71        ei->fd = 0;
  72        ei->op.proc_get_link = NULL;
  73        ei->pde = NULL;
  74        ei->sysctl = NULL;
  75        ei->sysctl_entry = NULL;
  76        ei->ns.ns = NULL;
  77        ei->ns.ns_ops = NULL;
  78        inode = &ei->vfs_inode;
  79        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  80        return inode;
  81}
  82
  83static void proc_i_callback(struct rcu_head *head)
  84{
  85        struct inode *inode = container_of(head, struct inode, i_rcu);
  86        kmem_cache_free(proc_inode_cachep, PROC_I(inode));
  87}
  88
  89static void proc_destroy_inode(struct inode *inode)
  90{
  91        call_rcu(&inode->i_rcu, proc_i_callback);
  92}
  93
  94static void init_once(void *foo)
  95{
  96        struct proc_inode *ei = (struct proc_inode *) foo;
  97
  98        inode_init_once(&ei->vfs_inode);
  99}
 100
 101void __init proc_init_inodecache(void)
 102{
 103        proc_inode_cachep = kmem_cache_create("proc_inode_cache",
 104                                             sizeof(struct proc_inode),
 105                                             0, (SLAB_RECLAIM_ACCOUNT|
 106                                                SLAB_MEM_SPREAD|SLAB_PANIC),
 107                                             init_once);
 108}
 109
 110static int proc_show_options(struct seq_file *seq, struct dentry *root)
 111{
 112        struct super_block *sb = root->d_sb;
 113        struct pid_namespace *pid = sb->s_fs_info;
 114
 115        if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
 116                seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
 117        if (pid->hide_pid != 0)
 118                seq_printf(seq, ",hidepid=%u", pid->hide_pid);
 119
 120        return 0;
 121}
 122
 123static const struct super_operations proc_sops = {
 124        .alloc_inode    = proc_alloc_inode,
 125        .destroy_inode  = proc_destroy_inode,
 126        .drop_inode     = generic_delete_inode,
 127        .evict_inode    = proc_evict_inode,
 128        .statfs         = simple_statfs,
 129        .remount_fs     = proc_remount,
 130        .show_options   = proc_show_options,
 131};
 132
 133enum {BIAS = -1U<<31};
 134
 135static inline int use_pde(struct proc_dir_entry *pde)
 136{
 137        return atomic_inc_unless_negative(&pde->in_use);
 138}
 139
 140static void unuse_pde(struct proc_dir_entry *pde)
 141{
 142        if (atomic_dec_return(&pde->in_use) == BIAS)
 143                complete(pde->pde_unload_completion);
 144}
 145
 146/* pde is locked */
 147static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
 148{
 149        if (pdeo->closing) {
 150                /* somebody else is doing that, just wait */
 151                DECLARE_COMPLETION_ONSTACK(c);
 152                pdeo->c = &c;
 153                spin_unlock(&pde->pde_unload_lock);
 154                wait_for_completion(&c);
 155                spin_lock(&pde->pde_unload_lock);
 156        } else {
 157                struct file *file;
 158                pdeo->closing = 1;
 159                spin_unlock(&pde->pde_unload_lock);
 160                file = pdeo->file;
 161                pde->proc_fops->release(file_inode(file), file);
 162                spin_lock(&pde->pde_unload_lock);
 163                list_del_init(&pdeo->lh);
 164                if (pdeo->c)
 165                        complete(pdeo->c);
 166                kfree(pdeo);
 167        }
 168}
 169
 170void proc_entry_rundown(struct proc_dir_entry *de)
 171{
 172        DECLARE_COMPLETION_ONSTACK(c);
 173        /* Wait until all existing callers into module are done. */
 174        de->pde_unload_completion = &c;
 175        if (atomic_add_return(BIAS, &de->in_use) != BIAS)
 176                wait_for_completion(&c);
 177
 178        spin_lock(&de->pde_unload_lock);
 179        while (!list_empty(&de->pde_openers)) {
 180                struct pde_opener *pdeo;
 181                pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
 182                close_pdeo(de, pdeo);
 183        }
 184        spin_unlock(&de->pde_unload_lock);
 185}
 186
 187static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
 188{
 189        struct proc_dir_entry *pde = PDE(file_inode(file));
 190        loff_t rv = -EINVAL;
 191        if (use_pde(pde)) {
 192                loff_t (*llseek)(struct file *, loff_t, int);
 193                llseek = pde->proc_fops->llseek;
 194                if (!llseek)
 195                        llseek = default_llseek;
 196                rv = llseek(file, offset, whence);
 197                unuse_pde(pde);
 198        }
 199        return rv;
 200}
 201
 202static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 203{
 204        ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
 205        struct proc_dir_entry *pde = PDE(file_inode(file));
 206        ssize_t rv = -EIO;
 207        if (use_pde(pde)) {
 208                read = pde->proc_fops->read;
 209                if (read)
 210                        rv = read(file, buf, count, ppos);
 211                unuse_pde(pde);
 212        }
 213        return rv;
 214}
 215
 216static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 217{
 218        ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
 219        struct proc_dir_entry *pde = PDE(file_inode(file));
 220        ssize_t rv = -EIO;
 221        if (use_pde(pde)) {
 222                write = pde->proc_fops->write;
 223                if (write)
 224                        rv = write(file, buf, count, ppos);
 225                unuse_pde(pde);
 226        }
 227        return rv;
 228}
 229
 230static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
 231{
 232        struct proc_dir_entry *pde = PDE(file_inode(file));
 233        unsigned int rv = DEFAULT_POLLMASK;
 234        unsigned int (*poll)(struct file *, struct poll_table_struct *);
 235        if (use_pde(pde)) {
 236                poll = pde->proc_fops->poll;
 237                if (poll)
 238                        rv = poll(file, pts);
 239                unuse_pde(pde);
 240        }
 241        return rv;
 242}
 243
 244static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 245{
 246        struct proc_dir_entry *pde = PDE(file_inode(file));
 247        long rv = -ENOTTY;
 248        long (*ioctl)(struct file *, unsigned int, unsigned long);
 249        if (use_pde(pde)) {
 250                ioctl = pde->proc_fops->unlocked_ioctl;
 251                if (ioctl)
 252                        rv = ioctl(file, cmd, arg);
 253                unuse_pde(pde);
 254        }
 255        return rv;
 256}
 257
 258#ifdef CONFIG_COMPAT
 259static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 260{
 261        struct proc_dir_entry *pde = PDE(file_inode(file));
 262        long rv = -ENOTTY;
 263        long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
 264        if (use_pde(pde)) {
 265                compat_ioctl = pde->proc_fops->compat_ioctl;
 266                if (compat_ioctl)
 267                        rv = compat_ioctl(file, cmd, arg);
 268                unuse_pde(pde);
 269        }
 270        return rv;
 271}
 272#endif
 273
 274static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
 275{
 276        struct proc_dir_entry *pde = PDE(file_inode(file));
 277        int rv = -EIO;
 278        int (*mmap)(struct file *, struct vm_area_struct *);
 279        if (use_pde(pde)) {
 280                mmap = pde->proc_fops->mmap;
 281                if (mmap)
 282                        rv = mmap(file, vma);
 283                unuse_pde(pde);
 284        }
 285        return rv;
 286}
 287
 288static unsigned long proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
 289{
 290        struct proc_dir_entry *pde = PDE(file_inode(file));
 291        unsigned long rv = -EIO;
 292        unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long) = NULL;
 293        if (use_pde(pde)) {
 294#ifdef CONFIG_MMU
 295                get_unmapped_area = current->mm->get_unmapped_area;
 296#endif
 297                if (pde->proc_fops->get_unmapped_area)
 298                        get_unmapped_area = pde->proc_fops->get_unmapped_area;
 299                if (get_unmapped_area)
 300                        rv = get_unmapped_area(file, orig_addr, len, pgoff, flags);
 301                unuse_pde(pde);
 302        }
 303        return rv;
 304}
 305
 306static int proc_reg_open(struct inode *inode, struct file *file)
 307{
 308        struct proc_dir_entry *pde = PDE(inode);
 309        int rv = 0;
 310        int (*open)(struct inode *, struct file *);
 311        int (*release)(struct inode *, struct file *);
 312        struct pde_opener *pdeo;
 313
 314        /*
 315         * What for, you ask? Well, we can have open, rmmod, remove_proc_entry
 316         * sequence. ->release won't be called because ->proc_fops will be
 317         * cleared. Depending on complexity of ->release, consequences vary.
 318         *
 319         * We can't wait for mercy when close will be done for real, it's
 320         * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
 321         * by hand in remove_proc_entry(). For this, save opener's credentials
 322         * for later.
 323         */
 324        pdeo = kzalloc(sizeof(struct pde_opener), GFP_KERNEL);
 325        if (!pdeo)
 326                return -ENOMEM;
 327
 328        if (!use_pde(pde)) {
 329                kfree(pdeo);
 330                return -ENOENT;
 331        }
 332        open = pde->proc_fops->open;
 333        release = pde->proc_fops->release;
 334
 335        if (open)
 336                rv = open(inode, file);
 337
 338        if (rv == 0 && release) {
 339                /* To know what to release. */
 340                pdeo->file = file;
 341                /* Strictly for "too late" ->release in proc_reg_release(). */
 342                spin_lock(&pde->pde_unload_lock);
 343                list_add(&pdeo->lh, &pde->pde_openers);
 344                spin_unlock(&pde->pde_unload_lock);
 345        } else
 346                kfree(pdeo);
 347
 348        unuse_pde(pde);
 349        return rv;
 350}
 351
 352static int proc_reg_release(struct inode *inode, struct file *file)
 353{
 354        struct proc_dir_entry *pde = PDE(inode);
 355        struct pde_opener *pdeo;
 356        spin_lock(&pde->pde_unload_lock);
 357        list_for_each_entry(pdeo, &pde->pde_openers, lh) {
 358                if (pdeo->file == file) {
 359                        close_pdeo(pde, pdeo);
 360                        break;
 361                }
 362        }
 363        spin_unlock(&pde->pde_unload_lock);
 364        return 0;
 365}
 366
 367static const struct file_operations proc_reg_file_ops = {
 368        .llseek         = proc_reg_llseek,
 369        .read           = proc_reg_read,
 370        .write          = proc_reg_write,
 371        .poll           = proc_reg_poll,
 372        .unlocked_ioctl = proc_reg_unlocked_ioctl,
 373#ifdef CONFIG_COMPAT
 374        .compat_ioctl   = proc_reg_compat_ioctl,
 375#endif
 376        .mmap           = proc_reg_mmap,
 377        .get_unmapped_area = proc_reg_get_unmapped_area,
 378        .open           = proc_reg_open,
 379        .release        = proc_reg_release,
 380};
 381
 382#ifdef CONFIG_COMPAT
 383static const struct file_operations proc_reg_file_ops_no_compat = {
 384        .llseek         = proc_reg_llseek,
 385        .read           = proc_reg_read,
 386        .write          = proc_reg_write,
 387        .poll           = proc_reg_poll,
 388        .unlocked_ioctl = proc_reg_unlocked_ioctl,
 389        .mmap           = proc_reg_mmap,
 390        .get_unmapped_area = proc_reg_get_unmapped_area,
 391        .open           = proc_reg_open,
 392        .release        = proc_reg_release,
 393};
 394#endif
 395
 396struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
 397{
 398        struct inode *inode = new_inode_pseudo(sb);
 399
 400        if (inode) {
 401                inode->i_ino = de->low_ino;
 402                inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 403                PROC_I(inode)->pde = de;
 404
 405                if (de->mode) {
 406                        inode->i_mode = de->mode;
 407                        inode->i_uid = de->uid;
 408                        inode->i_gid = de->gid;
 409                }
 410                if (de->size)
 411                        inode->i_size = de->size;
 412                if (de->nlink)
 413                        set_nlink(inode, de->nlink);
 414                WARN_ON(!de->proc_iops);
 415                inode->i_op = de->proc_iops;
 416                if (de->proc_fops) {
 417                        if (S_ISREG(inode->i_mode)) {
 418#ifdef CONFIG_COMPAT
 419                                if (!de->proc_fops->compat_ioctl)
 420                                        inode->i_fop =
 421                                                &proc_reg_file_ops_no_compat;
 422                                else
 423#endif
 424                                        inode->i_fop = &proc_reg_file_ops;
 425                        } else {
 426                                inode->i_fop = de->proc_fops;
 427                        }
 428                }
 429        } else
 430               pde_put(de);
 431        return inode;
 432}
 433
 434int proc_fill_super(struct super_block *s)
 435{
 436        struct inode *root_inode;
 437
 438        s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
 439        s->s_blocksize = 1024;
 440        s->s_blocksize_bits = 10;
 441        s->s_magic = PROC_SUPER_MAGIC;
 442        s->s_op = &proc_sops;
 443        s->s_time_gran = 1;
 444        
 445        pde_get(&proc_root);
 446        root_inode = proc_get_inode(s, &proc_root);
 447        if (!root_inode) {
 448                pr_err("proc_fill_super: get root inode failed\n");
 449                return -ENOMEM;
 450        }
 451
 452        s->s_root = d_make_root(root_inode);
 453        if (!s->s_root) {
 454                pr_err("proc_fill_super: allocate dentry failed\n");
 455                return -ENOMEM;
 456        }
 457
 458        return proc_setup_self(s);
 459}
 460