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