1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * fs/inotify_user.c - inotify support for userspace 4 * 5 * Authors: 6 * John McCutchan <ttb@tentacle.dhs.org> 7 * Robert Love <rml@novell.com> 8 * 9 * Copyright (C) 2005 John McCutchan 10 * Copyright 2006 Hewlett-Packard Development Company, L.P. 11 * 12 * Copyright (C) 2009 Eric Paris <Red Hat Inc> 13 * inotify was largely rewriten to make use of the fsnotify infrastructure 14 */ 15 16 #include <linux/dcache.h> /* d_unlinked */ 17 #include <linux/fs.h> /* struct inode */ 18 #include <linux/fsnotify_backend.h> 19 #include <linux/inotify.h> 20 #include <linux/path.h> /* struct path */ 21 #include <linux/slab.h> /* kmem_* */ 22 #include <linux/types.h> 23 #include <linux/sched.h> 24 #include <linux/sched/user.h> 25 #include <linux/sched/mm.h> 26 27 #include "inotify.h" 28 29 /* 30 * Check if 2 events contain the same information. 31 */ 32 static bool event_compare(struct fsnotify_event *old_fsn, 33 struct fsnotify_event *new_fsn) 34 { 35 struct inotify_event_info *old, *new; 36 37 old = INOTIFY_E(old_fsn); 38 new = INOTIFY_E(new_fsn); 39 if (old->mask & FS_IN_IGNORED) 40 return false; 41 if ((old->mask == new->mask) && 42 (old_fsn->inode == new_fsn->inode) && 43 (old->name_len == new->name_len) && 44 (!old->name_len || !strcmp(old->name, new->name))) 45 return true; 46 return false; 47 } 48 49 static int inotify_merge(struct list_head *list, 50 struct fsnotify_event *event) 51 { 52 struct fsnotify_event *last_event; 53 54 last_event = list_entry(list->prev, struct fsnotify_event, list); 55 return event_compare(last_event, event); 56 } 57 58 int inotify_handle_event(struct fsnotify_group *group, 59 struct inode *inode, 60 u32 mask, const void *data, int data_type, 61 const struct qstr *file_name, u32 cookie, 62 struct fsnotify_iter_info *iter_info) 63 { 64 struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info); 65 struct inotify_inode_mark *i_mark; 66 struct inotify_event_info *event; 67 struct fsnotify_event *fsn_event; 68 int ret; 69 int len = 0; 70 int alloc_len = sizeof(struct inotify_event_info); 71 72 if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info))) 73 return 0; 74 75 if ((inode_mark->mask & FS_EXCL_UNLINK) && 76 (data_type == FSNOTIFY_EVENT_PATH)) { 77 const struct path *path = data; 78 79 if (d_unlinked(path->dentry)) 80 return 0; 81 } 82 if (file_name) { 83 len = file_name->len; 84 alloc_len += len + 1; 85 } 86 87 pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode, 88 mask); 89 90 i_mark = container_of(inode_mark, struct inotify_inode_mark, 91 fsn_mark); 92 93 /* Whoever is interested in the event, pays for the allocation. */ 94 memalloc_use_memcg(group->memcg); 95 event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT); 96 memalloc_unuse_memcg(); 97 98 if (unlikely(!event)) { 99 /* 100 * Treat lost event due to ENOMEM the same way as queue 101 * overflow to let userspace know event was lost. 102 */ 103 fsnotify_queue_overflow(group); 104 return -ENOMEM; 105 } 106 107 /* 108 * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events 109 * for fanotify. inotify never reported IN_ISDIR with those events. 110 * It looks like an oversight, but to avoid the risk of breaking 111 * existing inotify programs, mask the flag out from those events. 112 */ 113 if (mask & (IN_MOVE_SELF | IN_DELETE_SELF)) 114 mask &= ~IN_ISDIR; 115 116 fsn_event = &event->fse; 117 fsnotify_init_event(fsn_event, inode); 118 event->mask = mask; 119 event->wd = i_mark->wd; 120 event->sync_cookie = cookie; 121 event->name_len = len; 122 if (len) 123 strcpy(event->name, file_name->name); 124 125 ret = fsnotify_add_event(group, fsn_event, inotify_merge); 126 if (ret) { 127 /* Our event wasn't used in the end. Free it. */ 128 fsnotify_destroy_event(group, fsn_event); 129 } 130 131 if (inode_mark->mask & IN_ONESHOT) 132 fsnotify_destroy_mark(inode_mark, group); 133 134 return 0; 135 } 136 137 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group) 138 { 139 inotify_ignored_and_remove_idr(fsn_mark, group); 140 } 141 142 /* 143 * This is NEVER supposed to be called. Inotify marks should either have been 144 * removed from the idr when the watch was removed or in the 145 * fsnotify_destroy_mark_by_group() call when the inotify instance was being 146 * torn down. This is only called if the idr is about to be freed but there 147 * are still marks in it. 148 */ 149 static int idr_callback(int id, void *p, void *data) 150 { 151 struct fsnotify_mark *fsn_mark; 152 struct inotify_inode_mark *i_mark; 153 static bool warned = false; 154 155 if (warned) 156 return 0; 157 158 warned = true; 159 fsn_mark = p; 160 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 161 162 WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in " 163 "idr. Probably leaking memory\n", id, p, data); 164 165 /* 166 * I'm taking the liberty of assuming that the mark in question is a 167 * valid address and I'm dereferencing it. This might help to figure 168 * out why we got here and the panic is no worse than the original 169 * BUG() that was here. 170 */ 171 if (fsn_mark) 172 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n", 173 fsn_mark->group, i_mark->wd); 174 return 0; 175 } 176 177 static void inotify_free_group_priv(struct fsnotify_group *group) 178 { 179 /* ideally the idr is empty and we won't hit the BUG in the callback */ 180 idr_for_each(&group->inotify_data.idr, idr_callback, group); 181 idr_destroy(&group->inotify_data.idr); 182 if (group->inotify_data.ucounts) 183 dec_inotify_instances(group->inotify_data.ucounts); 184 } 185 186 static void inotify_free_event(struct fsnotify_event *fsn_event) 187 { 188 kfree(INOTIFY_E(fsn_event)); 189 } 190 191 /* ding dong the mark is dead */ 192 static void inotify_free_mark(struct fsnotify_mark *fsn_mark) 193 { 194 struct inotify_inode_mark *i_mark; 195 196 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 197 198 kmem_cache_free(inotify_inode_mark_cachep, i_mark); 199 } 200 201 const struct fsnotify_ops inotify_fsnotify_ops = { 202 .handle_event = inotify_handle_event, 203 .free_group_priv = inotify_free_group_priv, 204 .free_event = inotify_free_event, 205 .freeing_mark = inotify_freeing_mark, 206 .free_mark = inotify_free_mark, 207 }; 208