LXR linux/fs/notify/inotify/inotify

   1/*
   2 * fs/inotify_user.c - inotify support for userspace
   3 *
   4 * Authors:
   5 *      John McCutchan  <ttb@tentacle.dhs.org>
   6 *      Robert Love     <rml@novell.com>
   7 *
   8 * Copyright (C) 2005 John McCutchan
   9 * Copyright 2006 Hewlett-Packard Development Company, L.P.
  10 *
  11 * Copyright (C) 2009 Eric Paris <Red Hat Inc>
  12 * inotify was largely rewriten to make use of the fsnotify infrastructure
  13 *
  14 * This program is free software; you can redistribute it and/or modify it
  15 * under the terms of the GNU General Public License as published by the
  16 * Free Software Foundation; either version 2, or (at your option) any
  17 * later version.
  18 *
  19 * This program is distributed in the hope that it will be useful, but
  20 * WITHOUT ANY WARRANTY; without even the implied warranty of
  21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22 * General Public License for more details.
  23 */
  24
  25#include <linux/dcache.h> /* d_unlinked */
  26#include <linux/fs.h> /* struct inode */
  27#include <linux/fsnotify_backend.h>
  28#include <linux/inotify.h>
  29#include <linux/path.h> /* struct path */
  30#include <linux/slab.h> /* kmem_* */
  31#include <linux/types.h>
  32#include <linux/sched.h>
  33#include <linux/sched/user.h>
  34
  35#include "inotify.h"
  36
  37/*
  38 * Check if 2 events contain the same information.
  39 */
  40static bool event_compare(struct fsnotify_event *old_fsn,
  41                          struct fsnotify_event *new_fsn)
  42{
  43        struct inotify_event_info *old, *new;
  44
  45        if (old_fsn->mask & FS_IN_IGNORED)
  46                return false;
  47        old = INOTIFY_E(old_fsn);
  48        new = INOTIFY_E(new_fsn);
  49        if ((old_fsn->mask == new_fsn->mask) &&
  50            (old_fsn->inode == new_fsn->inode) &&
  51            (old->name_len == new->name_len) &&
  52            (!old->name_len || !strcmp(old->name, new->name)))
  53                return true;
  54        return false;
  55}
  56
  57static int inotify_merge(struct list_head *list,
  58                          struct fsnotify_event *event)
  59{
  60        struct fsnotify_event *last_event;
  61
  62        last_event = list_entry(list->prev, struct fsnotify_event, list);
  63        return event_compare(last_event, event);
  64}
  65
  66int inotify_handle_event(struct fsnotify_group *group,
  67                         struct inode *inode,
  68                         struct fsnotify_mark *inode_mark,
  69                         struct fsnotify_mark *vfsmount_mark,
  70                         u32 mask, const void *data, int data_type,
  71                         const unsigned char *file_name, u32 cookie,
  72                         struct fsnotify_iter_info *iter_info)
  73{
  74        struct inotify_inode_mark *i_mark;
  75        struct inotify_event_info *event;
  76        struct fsnotify_event *fsn_event;
  77        int ret;
  78        int len = 0;
  79        int alloc_len = sizeof(struct inotify_event_info);
  80
  81        BUG_ON(vfsmount_mark);
  82
  83        if ((inode_mark->mask & FS_EXCL_UNLINK) &&
  84            (data_type == FSNOTIFY_EVENT_PATH)) {
  85                const struct path *path = data;
  86
  87                if (d_unlinked(path->dentry))
  88                        return 0;
  89        }
  90        if (file_name) {
  91                len = strlen(file_name);
  92                alloc_len += len + 1;
  93        }
  94
  95        pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
  96                 mask);
  97
  98        i_mark = container_of(inode_mark, struct inotify_inode_mark,
  99                              fsn_mark);
 100
 101        event = kmalloc(alloc_len, GFP_KERNEL);
 102        if (unlikely(!event)) {
 103                /*
 104                 * Treat lost event due to ENOMEM the same way as queue
 105                 * overflow to let userspace know event was lost.
 106                 */
 107                fsnotify_queue_overflow(group);
 108                return -ENOMEM;
 109        }
 110
 111        fsn_event = &event->fse;
 112        fsnotify_init_event(fsn_event, inode, mask);
 113        event->wd = i_mark->wd;
 114        event->sync_cookie = cookie;
 115        event->name_len = len;
 116        if (len)
 117                strcpy(event->name, file_name);
 118
 119        ret = fsnotify_add_event(group, fsn_event, inotify_merge);
 120        if (ret) {
 121                /* Our event wasn't used in the end. Free it. */
 122                fsnotify_destroy_event(group, fsn_event);
 123        }
 124
 125        if (inode_mark->mask & IN_ONESHOT)
 126                fsnotify_destroy_mark(inode_mark, group);
 127
 128        return 0;
 129}
 130
 131static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
 132{
 133        inotify_ignored_and_remove_idr(fsn_mark, group);
 134}
 135
 136/*
 137 * This is NEVER supposed to be called.  Inotify marks should either have been
 138 * removed from the idr when the watch was removed or in the
 139 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 140 * torn down.  This is only called if the idr is about to be freed but there
 141 * are still marks in it.
 142 */
 143static int idr_callback(int id, void *p, void *data)
 144{
 145        struct fsnotify_mark *fsn_mark;
 146        struct inotify_inode_mark *i_mark;
 147        static bool warned = false;
 148
 149        if (warned)
 150                return 0;
 151
 152        warned = true;
 153        fsn_mark = p;
 154        i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 155
 156        WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
 157                "idr.  Probably leaking memory\n", id, p, data);
 158
 159        /*
 160         * I'm taking the liberty of assuming that the mark in question is a
 161         * valid address and I'm dereferencing it.  This might help to figure
 162         * out why we got here and the panic is no worse than the original
 163         * BUG() that was here.
 164         */
 165        if (fsn_mark)
 166                printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
 167                        fsn_mark->group, i_mark->wd);
 168        return 0;
 169}
 170
 171static void inotify_free_group_priv(struct fsnotify_group *group)
 172{
 173        /* ideally the idr is empty and we won't hit the BUG in the callback */
 174        idr_for_each(&group->inotify_data.idr, idr_callback, group);
 175        idr_destroy(&group->inotify_data.idr);
 176        if (group->inotify_data.ucounts)
 177                dec_inotify_instances(group->inotify_data.ucounts);
 178}
 179
 180static void inotify_free_event(struct fsnotify_event *fsn_event)
 181{
 182        kfree(INOTIFY_E(fsn_event));
 183}
 184
 185/* ding dong the mark is dead */
 186static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
 187{
 188        struct inotify_inode_mark *i_mark;
 189
 190        i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 191
 192        kmem_cache_free(inotify_inode_mark_cachep, i_mark);
 193}
 194
 195const struct fsnotify_ops inotify_fsnotify_ops = {
 196        .handle_event = inotify_handle_event,
 197        .free_group_priv = inotify_free_group_priv,
 198        .free_event = inotify_free_event,
 199        .freeing_mark = inotify_freeing_mark,
 200        .free_mark = inotify_free_mark,
 201};
 202