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                          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                 return -ENOMEM;
 104
 105         fsn_event = &event->fse;
 106         fsnotify_init_event(fsn_event, inode, mask);
 107         event->wd = i_mark->wd;
 108         event->sync_cookie = cookie;
 109         event->name_len = len;
 110         if (len)
 111                 strcpy(event->name, file_name);
 112
 113         ret = fsnotify_add_event(group, fsn_event, inotify_merge);
 114         if (ret) {
 115                 /* Our event wasn't used in the end. Free it. */
 116                 fsnotify_destroy_event(group, fsn_event);
 117         }
 118
 119         if (inode_mark->mask & IN_ONESHOT)
 120                 fsnotify_destroy_mark(inode_mark, group);
 121
 122         return 0;
 123 }
 124
 125 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
 126 {
 127         inotify_ignored_and_remove_idr(fsn_mark, group);
 128 }
 129
 130 /*
 131  * This is NEVER supposed to be called.  Inotify marks should either have been
 132  * removed from the idr when the watch was removed or in the
 133  * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 134  * torn down.  This is only called if the idr is about to be freed but there
 135  * are still marks in it.
 136  */
 137 static int idr_callback(int id, void *p, void *data)
 138 {
 139         struct fsnotify_mark *fsn_mark;
 140         struct inotify_inode_mark *i_mark;
 141         static bool warned = false;
 142
 143         if (warned)
 144                 return 0;
 145
 146         warned = true;
 147         fsn_mark = p;
 148         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 149
 150         WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
 151                 "idr.  Probably leaking memory\n", id, p, data);
 152
 153         /*
 154          * I'm taking the liberty of assuming that the mark in question is a
 155          * valid address and I'm dereferencing it.  This might help to figure
 156          * out why we got here and the panic is no worse than the original
 157          * BUG() that was here.
 158          */
 159         if (fsn_mark)
 160                 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
 161                         fsn_mark->group, i_mark->wd);
 162         return 0;
 163 }
 164
 165 static void inotify_free_group_priv(struct fsnotify_group *group)
 166 {
 167         /* ideally the idr is empty and we won't hit the BUG in the callback */
 168         idr_for_each(&group->inotify_data.idr, idr_callback, group);
 169         idr_destroy(&group->inotify_data.idr);
 170         if (group->inotify_data.ucounts)
 171                 dec_inotify_instances(group->inotify_data.ucounts);
 172 }
 173
 174 static void inotify_free_event(struct fsnotify_event *fsn_event)
 175 {
 176         kfree(INOTIFY_E(fsn_event));
 177 }
 178
 179 /* ding dong the mark is dead */
 180 static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
 181 {
 182         struct inotify_inode_mark *i_mark;
 183
 184         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 185
 186         kmem_cache_free(inotify_inode_mark_cachep, i_mark);
 187 }
 188
 189 const struct fsnotify_ops inotify_fsnotify_ops = {
 190         .handle_event = inotify_handle_event,
 191         .free_group_priv = inotify_free_group_priv,
 192         .free_event = inotify_free_event,
 193         .freeing_mark = inotify_freeing_mark,
 194         .free_mark = inotify_free_mark,
 195 };