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 fsnotify_group *group, 50 struct fsnotify_event *event) 51 { 52 struct list_head *list = &group->notification_list; 53 struct fsnotify_event *last_event; 54 55 last_event = list_entry(list->prev, struct fsnotify_event, list); 56 return event_compare(last_event, event); 57 } 58 59 int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask, 60 struct inode *inode, struct inode *dir, 61 const struct qstr *name, u32 cookie) 62 { 63 struct inotify_inode_mark *i_mark; 64 struct inotify_event_info *event; 65 struct fsnotify_event *fsn_event; 66 struct fsnotify_group *group = inode_mark->group; 67 int ret; 68 int len = 0, wd; 69 int alloc_len = sizeof(struct inotify_event_info); 70 struct mem_cgroup *old_memcg; 71 72 if (name) { 73 len = name->len; 74 alloc_len += len + 1; 75 } 76 77 pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark, 78 mask); 79 80 i_mark = container_of(inode_mark, struct inotify_inode_mark, 81 fsn_mark); 82 83 /* 84 * We can be racing with mark being detached. Don't report event with 85 * invalid wd. 86 */ 87 wd = READ_ONCE(i_mark->wd); 88 if (wd == -1) 89 return 0; 90 /* 91 * Whoever is interested in the event, pays for the allocation. Do not 92 * trigger OOM killer in the target monitoring memcg as it may have 93 * security repercussion. 94 */ 95 old_memcg = set_active_memcg(group->memcg); 96 event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL); 97 set_active_memcg(old_memcg); 98 99 if (unlikely(!event)) { 100 /* 101 * Treat lost event due to ENOMEM the same way as queue 102 * overflow to let userspace know event was lost. 103 */ 104 fsnotify_queue_overflow(group); 105 return -ENOMEM; 106 } 107 108 /* 109 * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events 110 * for fanotify. inotify never reported IN_ISDIR with those events. 111 * It looks like an oversight, but to avoid the risk of breaking 112 * existing inotify programs, mask the flag out from those events. 113 */ 114 if (mask & (IN_MOVE_SELF | IN_DELETE_SELF)) 115 mask &= ~IN_ISDIR; 116 117 fsn_event = &event->fse; 118 fsnotify_init_event(fsn_event); 119 event->mask = mask; 120 event->wd = wd; 121 event->sync_cookie = cookie; 122 event->name_len = len; 123 if (len) 124 strcpy(event->name, name->name); 125 126 ret = fsnotify_add_event(group, fsn_event, inotify_merge); 127 if (ret) { 128 /* Our event wasn't used in the end. Free it. */ 129 fsnotify_destroy_event(group, fsn_event); 130 } 131 132 if (inode_mark->flags & FSNOTIFY_MARK_FLAG_IN_ONESHOT) 133 fsnotify_destroy_mark(inode_mark, group); 134 135 return 0; 136 } 137 138 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group) 139 { 140 inotify_ignored_and_remove_idr(fsn_mark, group); 141 } 142 143 /* 144 * This is NEVER supposed to be called. Inotify marks should either have been 145 * removed from the idr when the watch was removed or in the 146 * fsnotify_destroy_mark_by_group() call when the inotify instance was being 147 * torn down. This is only called if the idr is about to be freed but there 148 * are still marks in it. 149 */ 150 static int idr_callback(int id, void *p, void *data) 151 { 152 struct fsnotify_mark *fsn_mark; 153 struct inotify_inode_mark *i_mark; 154 static bool warned = false; 155 156 if (warned) 157 return 0; 158 159 warned = true; 160 fsn_mark = p; 161 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 162 163 WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in " 164 "idr. Probably leaking memory\n", id, p, data); 165 166 /* 167 * I'm taking the liberty of assuming that the mark in question is a 168 * valid address and I'm dereferencing it. This might help to figure 169 * out why we got here and the panic is no worse than the original 170 * BUG() that was here. 171 */ 172 if (fsn_mark) 173 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n", 174 fsn_mark->group, i_mark->wd); 175 return 0; 176 } 177 178 static void inotify_free_group_priv(struct fsnotify_group *group) 179 { 180 /* ideally the idr is empty and we won't hit the BUG in the callback */ 181 idr_for_each(&group->inotify_data.idr, idr_callback, group); 182 idr_destroy(&group->inotify_data.idr); 183 if (group->inotify_data.ucounts) 184 dec_inotify_instances(group->inotify_data.ucounts); 185 } 186 187 static void inotify_free_event(struct fsnotify_group *group, 188 struct fsnotify_event *fsn_event) 189 { 190 kfree(INOTIFY_E(fsn_event)); 191 } 192 193 /* ding dong the mark is dead */ 194 static void inotify_free_mark(struct fsnotify_mark *fsn_mark) 195 { 196 struct inotify_inode_mark *i_mark; 197 198 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 199 200 kmem_cache_free(inotify_inode_mark_cachep, i_mark); 201 } 202 203 const struct fsnotify_ops inotify_fsnotify_ops = { 204 .handle_inode_event = inotify_handle_inode_event, 205 .free_group_priv = inotify_free_group_priv, 206 .free_event = inotify_free_event, 207 .freeing_mark = inotify_freeing_mark, 208 .free_mark = inotify_free_mark, 209 }; 210