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 #include <linux/sched/mm.h>
  35
  36 #include "inotify.h"
  37
  38 /*
  39  * Check if 2 events contain the same information.
  40  */
  41 static bool event_compare(struct fsnotify_event *old_fsn,
  42                           struct fsnotify_event *new_fsn)
  43 {
  44         struct inotify_event_info *old, *new;
  45
  46         if (old_fsn->mask & FS_IN_IGNORED)
  47                 return false;
  48         old = INOTIFY_E(old_fsn);
  49         new = INOTIFY_E(new_fsn);
  50         if ((old_fsn->mask == new_fsn->mask) &&
  51             (old_fsn->inode == new_fsn->inode) &&
  52             (old->name_len == new->name_len) &&
  53             (!old->name_len || !strcmp(old->name, new->name)))
  54                 return true;
  55         return false;
  56 }
  57
  58 static int inotify_merge(struct list_head *list,
  59                           struct fsnotify_event *event)
  60 {
  61         struct fsnotify_event *last_event;
  62
  63         last_event = list_entry(list->prev, struct fsnotify_event, list);
  64         return event_compare(last_event, event);
  65 }
  66
  67 int inotify_handle_event(struct fsnotify_group *group,
  68                          struct inode *inode,
  69                          u32 mask, const void *data, int data_type,
  70                          const unsigned char *file_name, u32 cookie,
  71                          struct fsnotify_iter_info *iter_info)
  72 {
  73         struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
  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         if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info)))
  82                 return 0;
  83
  84         if ((inode_mark->mask & FS_EXCL_UNLINK) &&
  85             (data_type == FSNOTIFY_EVENT_PATH)) {
  86                 const struct path *path = data;
  87
  88                 if (d_unlinked(path->dentry))
  89                         return 0;
  90         }
  91         if (file_name) {
  92                 len = strlen(file_name);
  93                 alloc_len += len + 1;
  94         }
  95
  96         pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
  97                  mask);
  98
  99         i_mark = container_of(inode_mark, struct inotify_inode_mark,
 100                               fsn_mark);
 101
 102         /* Whoever is interested in the event, pays for the allocation. */
 103         memalloc_use_memcg(group->memcg);
 104         event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT);
 105         memalloc_unuse_memcg();
 106
 107         if (unlikely(!event)) {
 108                 /*
 109                  * Treat lost event due to ENOMEM the same way as queue
 110                  * overflow to let userspace know event was lost.
 111                  */
 112                 fsnotify_queue_overflow(group);
 113                 return -ENOMEM;
 114         }
 115
 116         fsn_event = &event->fse;
 117         fsnotify_init_event(fsn_event, inode, mask);
 118         event->wd = i_mark->wd;
 119         event->sync_cookie = cookie;
 120         event->name_len = len;
 121         if (len)
 122                 strcpy(event->name, file_name);
 123
 124         ret = fsnotify_add_event(group, fsn_event, inotify_merge);
 125         if (ret) {
 126                 /* Our event wasn't used in the end. Free it. */
 127                 fsnotify_destroy_event(group, fsn_event);
 128         }
 129
 130         if (inode_mark->mask & IN_ONESHOT)
 131                 fsnotify_destroy_mark(inode_mark, group);
 132
 133         return 0;
 134 }
 135
 136 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
 137 {
 138         inotify_ignored_and_remove_idr(fsn_mark, group);
 139 }
 140
 141 /*
 142  * This is NEVER supposed to be called.  Inotify marks should either have been
 143  * removed from the idr when the watch was removed or in the
 144  * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 145  * torn down.  This is only called if the idr is about to be freed but there
 146  * are still marks in it.
 147  */
 148 static int idr_callback(int id, void *p, void *data)
 149 {
 150         struct fsnotify_mark *fsn_mark;
 151         struct inotify_inode_mark *i_mark;
 152         static bool warned = false;
 153
 154         if (warned)
 155                 return 0;
 156
 157         warned = true;
 158         fsn_mark = p;
 159         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 160
 161         WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
 162                 "idr.  Probably leaking memory\n", id, p, data);
 163
 164         /*
 165          * I'm taking the liberty of assuming that the mark in question is a
 166          * valid address and I'm dereferencing it.  This might help to figure
 167          * out why we got here and the panic is no worse than the original
 168          * BUG() that was here.
 169          */
 170         if (fsn_mark)
 171                 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
 172                         fsn_mark->group, i_mark->wd);
 173         return 0;
 174 }
 175
 176 static void inotify_free_group_priv(struct fsnotify_group *group)
 177 {
 178         /* ideally the idr is empty and we won't hit the BUG in the callback */
 179         idr_for_each(&group->inotify_data.idr, idr_callback, group);
 180         idr_destroy(&group->inotify_data.idr);
 181         if (group->inotify_data.ucounts)
 182                 dec_inotify_instances(group->inotify_data.ucounts);
 183 }
 184
 185 static void inotify_free_event(struct fsnotify_event *fsn_event)
 186 {
 187         kfree(INOTIFY_E(fsn_event));
 188 }
 189
 190 /* ding dong the mark is dead */
 191 static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
 192 {
 193         struct inotify_inode_mark *i_mark;
 194
 195         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 196
 197         kmem_cache_free(inotify_inode_mark_cachep, i_mark);
 198 }
 199
 200 const struct fsnotify_ops inotify_fsnotify_ops = {
 201         .handle_event = inotify_handle_event,
 202         .free_group_priv = inotify_free_group_priv,
 203         .free_event = inotify_free_event,
 204         .freeing_mark = inotify_freeing_mark,
 205         .free_mark = inotify_free_mark,
 206 };