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- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * fs/inotify_user.c - inotify support for userspace
- *
- * Authors:
- * John McCutchan <ttb@tentacle.dhs.org>
- * Robert Love <rml@novell.com>
- *
- * Copyright (C) 2005 John McCutchan
- * Copyright 2006 Hewlett-Packard Development Company, L.P.
- *
- * Copyright (C) 2009 Eric Paris <Red Hat Inc>
- * inotify was largely rewriten to make use of the fsnotify infrastructure
- */
- #include <linux/dcache.h> /* d_unlinked */
- #include <linux/fs.h> /* struct inode */
- #include <linux/fsnotify_backend.h>
- #include <linux/inotify.h>
- #include <linux/path.h> /* struct path */
- #include <linux/slab.h> /* kmem_* */
- #include <linux/types.h>
- #include <linux/sched.h>
- #include <linux/sched/user.h>
- #include <linux/sched/mm.h>
- #include "inotify.h"
- /*
- * Check if 2 events contain the same information.
- */
- static bool event_compare(struct fsnotify_event *old_fsn,
- struct fsnotify_event *new_fsn)
- {
- struct inotify_event_info *old, *new;
- old = INOTIFY_E(old_fsn);
- new = INOTIFY_E(new_fsn);
- if (old->mask & FS_IN_IGNORED)
- return false;
- if ((old->mask == new->mask) &&
- (old->wd == new->wd) &&
- (old->name_len == new->name_len) &&
- (!old->name_len || !strcmp(old->name, new->name)))
- return true;
- return false;
- }
- static int inotify_merge(struct list_head *list,
- struct fsnotify_event *event)
- {
- struct fsnotify_event *last_event;
- last_event = list_entry(list->prev, struct fsnotify_event, list);
- return event_compare(last_event, event);
- }
- int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
- struct inode *inode, struct inode *dir,
- const struct qstr *name, u32 cookie)
- {
- struct inotify_inode_mark *i_mark;
- struct inotify_event_info *event;
- struct fsnotify_event *fsn_event;
- struct fsnotify_group *group = inode_mark->group;
- int ret;
- int len = 0;
- int alloc_len = sizeof(struct inotify_event_info);
- struct mem_cgroup *old_memcg;
- if (name) {
- len = name->len;
- alloc_len += len + 1;
- }
- pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark,
- mask);
- i_mark = container_of(inode_mark, struct inotify_inode_mark,
- fsn_mark);
- /*
- * Whoever is interested in the event, pays for the allocation. Do not
- * trigger OOM killer in the target monitoring memcg as it may have
- * security repercussion.
- */
- old_memcg = set_active_memcg(group->memcg);
- event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
- set_active_memcg(old_memcg);
- if (unlikely(!event)) {
- /*
- * Treat lost event due to ENOMEM the same way as queue
- * overflow to let userspace know event was lost.
- */
- fsnotify_queue_overflow(group);
- return -ENOMEM;
- }
- /*
- * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events
- * for fanotify. inotify never reported IN_ISDIR with those events.
- * It looks like an oversight, but to avoid the risk of breaking
- * existing inotify programs, mask the flag out from those events.
- */
- if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
- mask &= ~IN_ISDIR;
- fsn_event = &event->fse;
- fsnotify_init_event(fsn_event, 0);
- event->mask = mask;
- event->wd = i_mark->wd;
- event->sync_cookie = cookie;
- event->name_len = len;
- if (len)
- strcpy(event->name, name->name);
- ret = fsnotify_add_event(group, fsn_event, inotify_merge);
- if (ret) {
- /* Our event wasn't used in the end. Free it. */
- fsnotify_destroy_event(group, fsn_event);
- }
- if (inode_mark->mask & IN_ONESHOT)
- fsnotify_destroy_mark(inode_mark, group);
- return 0;
- }
- static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
- {
- inotify_ignored_and_remove_idr(fsn_mark, group);
- }
- /*
- * This is NEVER supposed to be called. Inotify marks should either have been
- * removed from the idr when the watch was removed or in the
- * fsnotify_destroy_mark_by_group() call when the inotify instance was being
- * torn down. This is only called if the idr is about to be freed but there
- * are still marks in it.
- */
- static int idr_callback(int id, void *p, void *data)
- {
- struct fsnotify_mark *fsn_mark;
- struct inotify_inode_mark *i_mark;
- static bool warned = false;
- if (warned)
- return 0;
- warned = true;
- fsn_mark = p;
- i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
- WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
- "idr. Probably leaking memory\n", id, p, data);
- /*
- * I'm taking the liberty of assuming that the mark in question is a
- * valid address and I'm dereferencing it. This might help to figure
- * out why we got here and the panic is no worse than the original
- * BUG() that was here.
- */
- if (fsn_mark)
- printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
- fsn_mark->group, i_mark->wd);
- return 0;
- }
- static void inotify_free_group_priv(struct fsnotify_group *group)
- {
- /* ideally the idr is empty and we won't hit the BUG in the callback */
- idr_for_each(&group->inotify_data.idr, idr_callback, group);
- idr_destroy(&group->inotify_data.idr);
- if (group->inotify_data.ucounts)
- dec_inotify_instances(group->inotify_data.ucounts);
- }
- static void inotify_free_event(struct fsnotify_event *fsn_event)
- {
- kfree(INOTIFY_E(fsn_event));
- }
- /* ding dong the mark is dead */
- static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
- {
- struct inotify_inode_mark *i_mark;
- i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
- kmem_cache_free(inotify_inode_mark_cachep, i_mark);
- }
- const struct fsnotify_ops inotify_fsnotify_ops = {
- .handle_inode_event = inotify_handle_inode_event,
- .free_group_priv = inotify_free_group_priv,
- .free_event = inotify_free_event,
- .freeing_mark = inotify_freeing_mark,
- .free_mark = inotify_free_mark,
- };
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