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->wd == new->wd) && 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 static int inotify_one_event(struct fsnotify_group *group, u32 mask, 59 struct fsnotify_mark *inode_mark, 60 const struct path *path, 61 const struct qstr *file_name, u32 cookie) 62 { 63 struct inotify_inode_mark *i_mark; 64 struct inotify_event_info *event; 65 struct fsnotify_event *fsn_event; 66 int ret; 67 int len = 0; 68 int alloc_len = sizeof(struct inotify_event_info); 69 struct mem_cgroup *old_memcg; 70 71 if ((inode_mark->mask & FS_EXCL_UNLINK) && 72 path && d_unlinked(path->dentry)) 73 return 0; 74 75 if (file_name) { 76 len = file_name->len; 77 alloc_len += len + 1; 78 } 79 80 pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark, 81 mask); 82 83 i_mark = container_of(inode_mark, struct inotify_inode_mark, 84 fsn_mark); 85 86 /* 87 * Whoever is interested in the event, pays for the allocation. Do not 88 * trigger OOM killer in the target monitoring memcg as it may have 89 * security repercussion. 90 */ 91 old_memcg = set_active_memcg(group->memcg); 92 event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL); 93 set_active_memcg(old_memcg); 94 95 if (unlikely(!event)) { 96 /* 97 * Treat lost event due to ENOMEM the same way as queue 98 * overflow to let userspace know event was lost. 99 */ 100 fsnotify_queue_overflow(group); 101 return -ENOMEM; 102 } 103 104 /* 105 * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events 106 * for fanotify. inotify never reported IN_ISDIR with those events. 107 * It looks like an oversight, but to avoid the risk of breaking 108 * existing inotify programs, mask the flag out from those events. 109 */ 110 if (mask & (IN_MOVE_SELF | IN_DELETE_SELF)) 111 mask &= ~IN_ISDIR; 112 113 fsn_event = &event->fse; 114 fsnotify_init_event(fsn_event, 0); 115 event->mask = mask; 116 event->wd = i_mark->wd; 117 event->sync_cookie = cookie; 118 event->name_len = len; 119 if (len) 120 strcpy(event->name, file_name->name); 121 122 ret = fsnotify_add_event(group, fsn_event, inotify_merge); 123 if (ret) { 124 /* Our event wasn't used in the end. Free it. */ 125 fsnotify_destroy_event(group, fsn_event); 126 } 127 128 if (inode_mark->mask & IN_ONESHOT) 129 fsnotify_destroy_mark(inode_mark, group); 130 131 return 0; 132 } 133 134 int inotify_handle_event(struct fsnotify_group *group, u32 mask, 135 const void *data, int data_type, struct inode *dir, 136 const struct qstr *file_name, u32 cookie, 137 struct fsnotify_iter_info *iter_info) 138 { 139 const struct path *path = fsnotify_data_path(data, data_type); 140 struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info); 141 struct fsnotify_mark *child_mark = fsnotify_iter_child_mark(iter_info); 142 int ret = 0; 143 144 if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info))) 145 return 0; 146 147 /* 148 * Some events cannot be sent on both parent and child marks 149 * (e.g. IN_CREATE). Those events are always sent on inode_mark. 150 * For events that are possible on both parent and child (e.g. IN_OPEN), 151 * event is sent on inode_mark with name if the parent is watching and 152 * is sent on child_mark without name if child is watching. 153 * If both parent and child are watching, report the event with child's 154 * name here and report another event without child's name below. 155 */ 156 if (inode_mark) 157 ret = inotify_one_event(group, mask, inode_mark, path, 158 file_name, cookie); 159 if (ret || !child_mark) 160 return ret; 161 162 return inotify_one_event(group, mask, child_mark, path, NULL, 0); 163 } 164 165 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group) 166 { 167 inotify_ignored_and_remove_idr(fsn_mark, group); 168 } 169 170 /* 171 * This is NEVER supposed to be called. Inotify marks should either have been 172 * removed from the idr when the watch was removed or in the 173 * fsnotify_destroy_mark_by_group() call when the inotify instance was being 174 * torn down. This is only called if the idr is about to be freed but there 175 * are still marks in it. 176 */ 177 static int idr_callback(int id, void *p, void *data) 178 { 179 struct fsnotify_mark *fsn_mark; 180 struct inotify_inode_mark *i_mark; 181 static bool warned = false; 182 183 if (warned) 184 return 0; 185 186 warned = true; 187 fsn_mark = p; 188 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 189 190 WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in " 191 "idr. Probably leaking memory\n", id, p, data); 192 193 /* 194 * I'm taking the liberty of assuming that the mark in question is a 195 * valid address and I'm dereferencing it. This might help to figure 196 * out why we got here and the panic is no worse than the original 197 * BUG() that was here. 198 */ 199 if (fsn_mark) 200 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n", 201 fsn_mark->group, i_mark->wd); 202 return 0; 203 } 204 205 static void inotify_free_group_priv(struct fsnotify_group *group) 206 { 207 /* ideally the idr is empty and we won't hit the BUG in the callback */ 208 idr_for_each(&group->inotify_data.idr, idr_callback, group); 209 idr_destroy(&group->inotify_data.idr); 210 if (group->inotify_data.ucounts) 211 dec_inotify_instances(group->inotify_data.ucounts); 212 } 213 214 static void inotify_free_event(struct fsnotify_event *fsn_event) 215 { 216 kfree(INOTIFY_E(fsn_event)); 217 } 218 219 /* ding dong the mark is dead */ 220 static void inotify_free_mark(struct fsnotify_mark *fsn_mark) 221 { 222 struct inotify_inode_mark *i_mark; 223 224 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 225 226 kmem_cache_free(inotify_inode_mark_cachep, i_mark); 227 } 228 229 const struct fsnotify_ops inotify_fsnotify_ops = { 230 .handle_event = inotify_handle_event, 231 .free_group_priv = inotify_free_group_priv, 232 .free_event = inotify_free_event, 233 .freeing_mark = inotify_freeing_mark, 234 .free_mark = inotify_free_mark, 235 }; 236