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