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                          u32 mask, const void *data, int data_type,
  69                          const unsigned char *file_name, u32 cookie,
  70                          struct fsnotify_iter_info *iter_info)
  71 {
  72         struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
  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         if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info)))
  81                 return 0;
  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
 131 static 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  */
 143 static 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
 171 static 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
 180 static 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 */
 186 static 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
 195 const 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 };