fs/notify/inotify/inotify_fsnotify.c

   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  */
  40 static 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
  57 static 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
  66 int 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 {
  73         struct inotify_inode_mark *i_mark;
  74         struct inotify_event_info *event;
  75         struct fsnotify_event *fsn_event;
  76         int ret;
  77         int len = 0;
  78         int alloc_len = sizeof(struct inotify_event_info);
  79
  80         BUG_ON(vfsmount_mark);
  81
  82         if ((inode_mark->mask & FS_EXCL_UNLINK) &&
  83             (data_type == FSNOTIFY_EVENT_PATH)) {
  84                 const struct path *path = data;
  85
  86                 if (d_unlinked(path->dentry))
  87                         return 0;
  88         }
  89         if (file_name) {
  90                 len = strlen(file_name);
  91                 alloc_len += len + 1;
  92         }
  93
  94         pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
  95                  mask);
  96
  97         i_mark = container_of(inode_mark, struct inotify_inode_mark,
  98                               fsn_mark);
  99
 100         event = kmalloc(alloc_len, GFP_KERNEL);
 101         if (unlikely(!event))
 102                 return -ENOMEM;
 103
 104         fsn_event = &event->fse;
 105         fsnotify_init_event(fsn_event, inode, mask);
 106         event->wd = i_mark->wd;
 107         event->sync_cookie = cookie;
 108         event->name_len = len;
 109         if (len)
 110                 strcpy(event->name, file_name);
 111
 112         ret = fsnotify_add_event(group, fsn_event, inotify_merge);
 113         if (ret) {
 114                 /* Our event wasn't used in the end. Free it. */
 115                 fsnotify_destroy_event(group, fsn_event);
 116         }
 117
 118         if (inode_mark->mask & IN_ONESHOT)
 119                 fsnotify_destroy_mark(inode_mark, group);
 120
 121         return 0;
 122 }
 123
 124 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
 125 {
 126         inotify_ignored_and_remove_idr(fsn_mark, group);
 127 }
 128
 129 /*
 130  * This is NEVER supposed to be called.  Inotify marks should either have been
 131  * removed from the idr when the watch was removed or in the
 132  * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 133  * torn down.  This is only called if the idr is about to be freed but there
 134  * are still marks in it.
 135  */
 136 static int idr_callback(int id, void *p, void *data)
 137 {
 138         struct fsnotify_mark *fsn_mark;
 139         struct inotify_inode_mark *i_mark;
 140         static bool warned = false;
 141
 142         if (warned)
 143                 return 0;
 144
 145         warned = true;
 146         fsn_mark = p;
 147         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 148
 149         WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
 150                 "idr.  Probably leaking memory\n", id, p, data);
 151
 152         /*
 153          * I'm taking the liberty of assuming that the mark in question is a
 154          * valid address and I'm dereferencing it.  This might help to figure
 155          * out why we got here and the panic is no worse than the original
 156          * BUG() that was here.
 157          */
 158         if (fsn_mark)
 159                 printk(KERN_WARNING "fsn_mark->group=%p inode=%p wd=%d\n",
 160                         fsn_mark->group, fsn_mark->inode, i_mark->wd);
 161         return 0;
 162 }
 163
 164 static void inotify_free_group_priv(struct fsnotify_group *group)
 165 {
 166         /* ideally the idr is empty and we won't hit the BUG in the callback */
 167         idr_for_each(&group->inotify_data.idr, idr_callback, group);
 168         idr_destroy(&group->inotify_data.idr);
 169         if (group->inotify_data.ucounts)
 170                 dec_inotify_instances(group->inotify_data.ucounts);
 171 }
 172
 173 static void inotify_free_event(struct fsnotify_event *fsn_event)
 174 {
 175         kfree(INOTIFY_E(fsn_event));
 176 }
 177
 178 const struct fsnotify_ops inotify_fsnotify_ops = {
 179         .handle_event = inotify_handle_event,
 180         .free_group_priv = inotify_free_group_priv,
 181         .free_event = inotify_free_event,
 182         .freeing_mark = inotify_freeing_mark,
 183 };