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 }; 202