768 lines
20 KiB
C
768 lines
20 KiB
C
/*
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* fs/inotify_user.c - inotify support for userspace
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*
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* Authors:
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* John McCutchan <ttb@tentacle.dhs.org>
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* Robert Love <rml@novell.com>
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*
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* Copyright (C) 2005 John McCutchan
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* Copyright 2006 Hewlett-Packard Development Company, L.P.
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*
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* Copyright (C) 2009 Eric Paris <Red Hat Inc>
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* inotify was largely rewriten to make use of the fsnotify infrastructure
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/file.h>
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#include <linux/fs.h> /* struct inode */
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#include <linux/fsnotify_backend.h>
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#include <linux/idr.h>
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#include <linux/init.h> /* module_init */
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#include <linux/inotify.h>
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#include <linux/kernel.h> /* roundup() */
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#include <linux/magic.h> /* superblock magic number */
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#include <linux/mount.h> /* mntget */
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#include <linux/namei.h> /* LOOKUP_FOLLOW */
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#include <linux/path.h> /* struct path */
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#include <linux/sched.h> /* struct user */
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#include <linux/slab.h> /* struct kmem_cache */
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#include <linux/syscalls.h>
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#include <linux/types.h>
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#include <linux/uaccess.h>
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#include <linux/poll.h>
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#include <linux/wait.h>
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#include "inotify.h"
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#include <asm/ioctls.h>
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static struct vfsmount *inotify_mnt __read_mostly;
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/* this just sits here and wastes global memory. used to just pad userspace messages with zeros */
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static struct inotify_event nul_inotify_event;
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/* these are configurable via /proc/sys/fs/inotify/ */
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static int inotify_max_user_instances __read_mostly;
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static int inotify_max_queued_events __read_mostly;
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int inotify_max_user_watches __read_mostly;
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static struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
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struct kmem_cache *event_priv_cachep __read_mostly;
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/*
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* When inotify registers a new group it increments this and uses that
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* value as an offset to set the fsnotify group "name" and priority.
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*/
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static atomic_t inotify_grp_num;
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#ifdef CONFIG_SYSCTL
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#include <linux/sysctl.h>
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static int zero;
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ctl_table inotify_table[] = {
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{
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.ctl_name = INOTIFY_MAX_USER_INSTANCES,
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.procname = "max_user_instances",
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.data = &inotify_max_user_instances,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.strategy = &sysctl_intvec,
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.extra1 = &zero,
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},
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{
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.ctl_name = INOTIFY_MAX_USER_WATCHES,
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.procname = "max_user_watches",
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.data = &inotify_max_user_watches,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.strategy = &sysctl_intvec,
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.extra1 = &zero,
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},
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{
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.ctl_name = INOTIFY_MAX_QUEUED_EVENTS,
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.procname = "max_queued_events",
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.data = &inotify_max_queued_events,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.strategy = &sysctl_intvec,
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.extra1 = &zero
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},
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{ .ctl_name = 0 }
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};
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#endif /* CONFIG_SYSCTL */
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static inline __u32 inotify_arg_to_mask(u32 arg)
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{
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__u32 mask;
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/* everything should accept their own ignored and cares about children */
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mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD);
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/* mask off the flags used to open the fd */
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mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT));
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return mask;
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}
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static inline u32 inotify_mask_to_arg(__u32 mask)
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{
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return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED |
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IN_Q_OVERFLOW);
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}
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/* intofiy userspace file descriptor functions */
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static unsigned int inotify_poll(struct file *file, poll_table *wait)
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{
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struct fsnotify_group *group = file->private_data;
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int ret = 0;
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poll_wait(file, &group->notification_waitq, wait);
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mutex_lock(&group->notification_mutex);
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if (!fsnotify_notify_queue_is_empty(group))
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ret = POLLIN | POLLRDNORM;
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mutex_unlock(&group->notification_mutex);
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return ret;
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}
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/*
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* Get an inotify_kernel_event if one exists and is small
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* enough to fit in "count". Return an error pointer if
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* not large enough.
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*
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* Called with the group->notification_mutex held.
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*/
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static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
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size_t count)
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{
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size_t event_size = sizeof(struct inotify_event);
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struct fsnotify_event *event;
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if (fsnotify_notify_queue_is_empty(group))
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return NULL;
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event = fsnotify_peek_notify_event(group);
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event_size += roundup(event->name_len, event_size);
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if (event_size > count)
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return ERR_PTR(-EINVAL);
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/* held the notification_mutex the whole time, so this is the
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* same event we peeked above */
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fsnotify_remove_notify_event(group);
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return event;
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}
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/*
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* Copy an event to user space, returning how much we copied.
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*
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* We already checked that the event size is smaller than the
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* buffer we had in "get_one_event()" above.
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*/
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static ssize_t copy_event_to_user(struct fsnotify_group *group,
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struct fsnotify_event *event,
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char __user *buf)
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{
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struct inotify_event inotify_event;
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struct fsnotify_event_private_data *fsn_priv;
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struct inotify_event_private_data *priv;
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size_t event_size = sizeof(struct inotify_event);
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size_t name_len;
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/* we get the inotify watch descriptor from the event private data */
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spin_lock(&event->lock);
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fsn_priv = fsnotify_remove_priv_from_event(group, event);
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spin_unlock(&event->lock);
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if (!fsn_priv)
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inotify_event.wd = -1;
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else {
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priv = container_of(fsn_priv, struct inotify_event_private_data,
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fsnotify_event_priv_data);
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inotify_event.wd = priv->wd;
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inotify_free_event_priv(fsn_priv);
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}
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/* round up event->name_len so it is a multiple of event_size */
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name_len = roundup(event->name_len, event_size);
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inotify_event.len = name_len;
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inotify_event.mask = inotify_mask_to_arg(event->mask);
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inotify_event.cookie = event->sync_cookie;
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/* send the main event */
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if (copy_to_user(buf, &inotify_event, event_size))
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return -EFAULT;
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buf += event_size;
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/*
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* fsnotify only stores the pathname, so here we have to send the pathname
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* and then pad that pathname out to a multiple of sizeof(inotify_event)
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* with zeros. I get my zeros from the nul_inotify_event.
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*/
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if (name_len) {
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unsigned int len_to_zero = name_len - event->name_len;
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/* copy the path name */
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if (copy_to_user(buf, event->file_name, event->name_len))
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return -EFAULT;
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buf += event->name_len;
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/* fill userspace with 0's from nul_inotify_event */
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if (copy_to_user(buf, &nul_inotify_event, len_to_zero))
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return -EFAULT;
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buf += len_to_zero;
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event_size += name_len;
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}
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return event_size;
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}
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static ssize_t inotify_read(struct file *file, char __user *buf,
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size_t count, loff_t *pos)
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{
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struct fsnotify_group *group;
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struct fsnotify_event *kevent;
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char __user *start;
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int ret;
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DEFINE_WAIT(wait);
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start = buf;
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group = file->private_data;
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while (1) {
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prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
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mutex_lock(&group->notification_mutex);
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kevent = get_one_event(group, count);
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mutex_unlock(&group->notification_mutex);
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if (kevent) {
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ret = PTR_ERR(kevent);
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if (IS_ERR(kevent))
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break;
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ret = copy_event_to_user(group, kevent, buf);
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fsnotify_put_event(kevent);
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if (ret < 0)
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break;
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buf += ret;
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count -= ret;
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continue;
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}
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ret = -EAGAIN;
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if (file->f_flags & O_NONBLOCK)
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break;
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ret = -EINTR;
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if (signal_pending(current))
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break;
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if (start != buf)
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break;
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schedule();
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}
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finish_wait(&group->notification_waitq, &wait);
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if (start != buf && ret != -EFAULT)
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ret = buf - start;
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return ret;
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}
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static int inotify_fasync(int fd, struct file *file, int on)
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{
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struct fsnotify_group *group = file->private_data;
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return fasync_helper(fd, file, on, &group->inotify_data.fa) >= 0 ? 0 : -EIO;
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}
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static int inotify_release(struct inode *ignored, struct file *file)
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{
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struct fsnotify_group *group = file->private_data;
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struct user_struct *user = group->inotify_data.user;
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fsnotify_clear_marks_by_group(group);
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/* free this group, matching get was inotify_init->fsnotify_obtain_group */
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fsnotify_put_group(group);
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atomic_dec(&user->inotify_devs);
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return 0;
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}
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static long inotify_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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struct fsnotify_group *group;
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struct fsnotify_event_holder *holder;
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struct fsnotify_event *event;
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void __user *p;
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int ret = -ENOTTY;
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size_t send_len = 0;
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group = file->private_data;
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p = (void __user *) arg;
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switch (cmd) {
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case FIONREAD:
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mutex_lock(&group->notification_mutex);
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list_for_each_entry(holder, &group->notification_list, event_list) {
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event = holder->event;
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send_len += sizeof(struct inotify_event);
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send_len += roundup(event->name_len,
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sizeof(struct inotify_event));
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}
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mutex_unlock(&group->notification_mutex);
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ret = put_user(send_len, (int __user *) p);
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break;
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}
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return ret;
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}
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static const struct file_operations inotify_fops = {
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.poll = inotify_poll,
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.read = inotify_read,
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.fasync = inotify_fasync,
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.release = inotify_release,
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.unlocked_ioctl = inotify_ioctl,
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.compat_ioctl = inotify_ioctl,
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};
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/*
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* find_inode - resolve a user-given path to a specific inode
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*/
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static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags)
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{
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int error;
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error = user_path_at(AT_FDCWD, dirname, flags, path);
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if (error)
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return error;
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/* you can only watch an inode if you have read permissions on it */
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error = inode_permission(path->dentry->d_inode, MAY_READ);
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if (error)
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path_put(path);
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return error;
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}
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static void inotify_remove_from_idr(struct fsnotify_group *group,
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struct inotify_inode_mark_entry *ientry)
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{
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struct idr *idr;
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spin_lock(&group->inotify_data.idr_lock);
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idr = &group->inotify_data.idr;
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idr_remove(idr, ientry->wd);
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spin_unlock(&group->inotify_data.idr_lock);
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ientry->wd = -1;
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}
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/*
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* Send IN_IGNORED for this wd, remove this wd from the idr, and drop the
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* internal reference help on the mark because it is in the idr.
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*/
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void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry,
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struct fsnotify_group *group)
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{
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struct inotify_inode_mark_entry *ientry;
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struct fsnotify_event *ignored_event;
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struct inotify_event_private_data *event_priv;
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struct fsnotify_event_private_data *fsn_event_priv;
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ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL,
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FSNOTIFY_EVENT_NONE, NULL, 0,
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GFP_NOFS);
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if (!ignored_event)
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return;
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ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
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event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS);
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if (unlikely(!event_priv))
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goto skip_send_ignore;
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fsn_event_priv = &event_priv->fsnotify_event_priv_data;
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fsn_event_priv->group = group;
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event_priv->wd = ientry->wd;
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fsnotify_add_notify_event(group, ignored_event, fsn_event_priv);
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/* did the private data get added? */
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if (list_empty(&fsn_event_priv->event_list))
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inotify_free_event_priv(fsn_event_priv);
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skip_send_ignore:
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/* matches the reference taken when the event was created */
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fsnotify_put_event(ignored_event);
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/* remove this entry from the idr */
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inotify_remove_from_idr(group, ientry);
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/* removed from idr, drop that reference */
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fsnotify_put_mark(entry);
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atomic_dec(&group->inotify_data.user->inotify_watches);
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}
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/* ding dong the mark is dead */
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static void inotify_free_mark(struct fsnotify_mark_entry *entry)
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{
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struct inotify_inode_mark_entry *ientry = (struct inotify_inode_mark_entry *)entry;
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kmem_cache_free(inotify_inode_mark_cachep, ientry);
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}
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static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
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{
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struct fsnotify_mark_entry *entry = NULL;
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struct inotify_inode_mark_entry *ientry;
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struct inotify_inode_mark_entry *tmp_ientry;
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int ret = 0;
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int add = (arg & IN_MASK_ADD);
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__u32 mask;
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__u32 old_mask, new_mask;
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/* don't allow invalid bits: we don't want flags set */
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mask = inotify_arg_to_mask(arg);
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if (unlikely(!mask))
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return -EINVAL;
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tmp_ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
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if (unlikely(!tmp_ientry))
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return -ENOMEM;
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/* we set the mask at the end after attaching it */
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fsnotify_init_mark(&tmp_ientry->fsn_entry, inotify_free_mark);
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tmp_ientry->wd = -1;
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find_entry:
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spin_lock(&inode->i_lock);
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entry = fsnotify_find_mark_entry(group, inode);
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spin_unlock(&inode->i_lock);
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if (entry) {
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ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
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} else {
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ret = -ENOSPC;
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if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
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goto out_err;
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retry:
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ret = -ENOMEM;
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if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL)))
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goto out_err;
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spin_lock(&group->inotify_data.idr_lock);
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ret = idr_get_new_above(&group->inotify_data.idr, &tmp_ientry->fsn_entry,
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group->inotify_data.last_wd,
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&tmp_ientry->wd);
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spin_unlock(&group->inotify_data.idr_lock);
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if (ret) {
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if (ret == -EAGAIN)
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goto retry;
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goto out_err;
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}
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ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode);
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if (ret) {
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inotify_remove_from_idr(group, tmp_ientry);
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if (ret == -EEXIST)
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goto find_entry;
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goto out_err;
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}
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/* tmp_ientry has been added to the inode, so we are all set up.
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* now we just need to make sure tmp_ientry doesn't get freed and
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* we need to set up entry and ientry so the generic code can
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* do its thing. */
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ientry = tmp_ientry;
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entry = &ientry->fsn_entry;
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tmp_ientry = NULL;
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atomic_inc(&group->inotify_data.user->inotify_watches);
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/* update the idr hint */
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group->inotify_data.last_wd = ientry->wd;
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/* we put the mark on the idr, take a reference */
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fsnotify_get_mark(entry);
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}
|
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|
|
ret = ientry->wd;
|
|
|
|
spin_lock(&entry->lock);
|
|
|
|
old_mask = entry->mask;
|
|
if (add) {
|
|
entry->mask |= mask;
|
|
new_mask = entry->mask;
|
|
} else {
|
|
entry->mask = mask;
|
|
new_mask = entry->mask;
|
|
}
|
|
|
|
spin_unlock(&entry->lock);
|
|
|
|
if (old_mask != new_mask) {
|
|
/* more bits in old than in new? */
|
|
int dropped = (old_mask & ~new_mask);
|
|
/* more bits in this entry than the inode's mask? */
|
|
int do_inode = (new_mask & ~inode->i_fsnotify_mask);
|
|
/* more bits in this entry than the group? */
|
|
int do_group = (new_mask & ~group->mask);
|
|
|
|
/* update the inode with this new entry */
|
|
if (dropped || do_inode)
|
|
fsnotify_recalc_inode_mask(inode);
|
|
|
|
/* update the group mask with the new mask */
|
|
if (dropped || do_group)
|
|
fsnotify_recalc_group_mask(group);
|
|
}
|
|
|
|
/* this either matches fsnotify_find_mark_entry, or init_mark_entry
|
|
* depending on which path we took... */
|
|
fsnotify_put_mark(entry);
|
|
|
|
out_err:
|
|
/* could be an error, could be that we found an existing mark */
|
|
if (tmp_ientry) {
|
|
/* on the idr but didn't make it on the inode */
|
|
if (tmp_ientry->wd != -1)
|
|
inotify_remove_from_idr(group, tmp_ientry);
|
|
kmem_cache_free(inotify_inode_mark_cachep, tmp_ientry);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static struct fsnotify_group *inotify_new_group(struct user_struct *user, unsigned int max_events)
|
|
{
|
|
struct fsnotify_group *group;
|
|
unsigned int grp_num;
|
|
|
|
/* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
|
|
grp_num = (INOTIFY_GROUP_NUM - atomic_inc_return(&inotify_grp_num));
|
|
group = fsnotify_obtain_group(grp_num, 0, &inotify_fsnotify_ops);
|
|
if (IS_ERR(group))
|
|
return group;
|
|
|
|
group->max_events = max_events;
|
|
|
|
spin_lock_init(&group->inotify_data.idr_lock);
|
|
idr_init(&group->inotify_data.idr);
|
|
group->inotify_data.last_wd = 0;
|
|
group->inotify_data.user = user;
|
|
group->inotify_data.fa = NULL;
|
|
|
|
return group;
|
|
}
|
|
|
|
|
|
/* inotify syscalls */
|
|
SYSCALL_DEFINE1(inotify_init1, int, flags)
|
|
{
|
|
struct fsnotify_group *group;
|
|
struct user_struct *user;
|
|
struct file *filp;
|
|
int fd, ret;
|
|
|
|
/* Check the IN_* constants for consistency. */
|
|
BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
|
|
BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
|
|
|
|
if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
|
|
return -EINVAL;
|
|
|
|
fd = get_unused_fd_flags(flags & O_CLOEXEC);
|
|
if (fd < 0)
|
|
return fd;
|
|
|
|
filp = get_empty_filp();
|
|
if (!filp) {
|
|
ret = -ENFILE;
|
|
goto out_put_fd;
|
|
}
|
|
|
|
user = get_current_user();
|
|
if (unlikely(atomic_read(&user->inotify_devs) >=
|
|
inotify_max_user_instances)) {
|
|
ret = -EMFILE;
|
|
goto out_free_uid;
|
|
}
|
|
|
|
/* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
|
|
group = inotify_new_group(user, inotify_max_queued_events);
|
|
if (IS_ERR(group)) {
|
|
ret = PTR_ERR(group);
|
|
goto out_free_uid;
|
|
}
|
|
|
|
filp->f_op = &inotify_fops;
|
|
filp->f_path.mnt = mntget(inotify_mnt);
|
|
filp->f_path.dentry = dget(inotify_mnt->mnt_root);
|
|
filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping;
|
|
filp->f_mode = FMODE_READ;
|
|
filp->f_flags = O_RDONLY | (flags & O_NONBLOCK);
|
|
filp->private_data = group;
|
|
|
|
atomic_inc(&user->inotify_devs);
|
|
|
|
fd_install(fd, filp);
|
|
|
|
return fd;
|
|
|
|
out_free_uid:
|
|
free_uid(user);
|
|
put_filp(filp);
|
|
out_put_fd:
|
|
put_unused_fd(fd);
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE0(inotify_init)
|
|
{
|
|
return sys_inotify_init1(0);
|
|
}
|
|
|
|
SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
|
|
u32, mask)
|
|
{
|
|
struct fsnotify_group *group;
|
|
struct inode *inode;
|
|
struct path path;
|
|
struct file *filp;
|
|
int ret, fput_needed;
|
|
unsigned flags = 0;
|
|
|
|
filp = fget_light(fd, &fput_needed);
|
|
if (unlikely(!filp))
|
|
return -EBADF;
|
|
|
|
/* verify that this is indeed an inotify instance */
|
|
if (unlikely(filp->f_op != &inotify_fops)) {
|
|
ret = -EINVAL;
|
|
goto fput_and_out;
|
|
}
|
|
|
|
if (!(mask & IN_DONT_FOLLOW))
|
|
flags |= LOOKUP_FOLLOW;
|
|
if (mask & IN_ONLYDIR)
|
|
flags |= LOOKUP_DIRECTORY;
|
|
|
|
ret = inotify_find_inode(pathname, &path, flags);
|
|
if (ret)
|
|
goto fput_and_out;
|
|
|
|
/* inode held in place by reference to path; group by fget on fd */
|
|
inode = path.dentry->d_inode;
|
|
group = filp->private_data;
|
|
|
|
/* create/update an inode mark */
|
|
ret = inotify_update_watch(group, inode, mask);
|
|
if (unlikely(ret))
|
|
goto path_put_and_out;
|
|
|
|
path_put_and_out:
|
|
path_put(&path);
|
|
fput_and_out:
|
|
fput_light(filp, fput_needed);
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
|
|
{
|
|
struct fsnotify_group *group;
|
|
struct fsnotify_mark_entry *entry;
|
|
struct file *filp;
|
|
int ret = 0, fput_needed;
|
|
|
|
filp = fget_light(fd, &fput_needed);
|
|
if (unlikely(!filp))
|
|
return -EBADF;
|
|
|
|
/* verify that this is indeed an inotify instance */
|
|
if (unlikely(filp->f_op != &inotify_fops)) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
group = filp->private_data;
|
|
|
|
spin_lock(&group->inotify_data.idr_lock);
|
|
entry = idr_find(&group->inotify_data.idr, wd);
|
|
if (unlikely(!entry)) {
|
|
spin_unlock(&group->inotify_data.idr_lock);
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
fsnotify_get_mark(entry);
|
|
spin_unlock(&group->inotify_data.idr_lock);
|
|
|
|
fsnotify_destroy_mark_by_entry(entry);
|
|
fsnotify_put_mark(entry);
|
|
|
|
out:
|
|
fput_light(filp, fput_needed);
|
|
return ret;
|
|
}
|
|
|
|
static int
|
|
inotify_get_sb(struct file_system_type *fs_type, int flags,
|
|
const char *dev_name, void *data, struct vfsmount *mnt)
|
|
{
|
|
return get_sb_pseudo(fs_type, "inotify", NULL,
|
|
INOTIFYFS_SUPER_MAGIC, mnt);
|
|
}
|
|
|
|
static struct file_system_type inotify_fs_type = {
|
|
.name = "inotifyfs",
|
|
.get_sb = inotify_get_sb,
|
|
.kill_sb = kill_anon_super,
|
|
};
|
|
|
|
/*
|
|
* inotify_user_setup - Our initialization function. Note that we cannnot return
|
|
* error because we have compiled-in VFS hooks. So an (unlikely) failure here
|
|
* must result in panic().
|
|
*/
|
|
static int __init inotify_user_setup(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = register_filesystem(&inotify_fs_type);
|
|
if (unlikely(ret))
|
|
panic("inotify: register_filesystem returned %d!\n", ret);
|
|
|
|
inotify_mnt = kern_mount(&inotify_fs_type);
|
|
if (IS_ERR(inotify_mnt))
|
|
panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt));
|
|
|
|
inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark_entry, SLAB_PANIC);
|
|
event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC);
|
|
|
|
inotify_max_queued_events = 16384;
|
|
inotify_max_user_instances = 128;
|
|
inotify_max_user_watches = 8192;
|
|
|
|
return 0;
|
|
}
|
|
module_init(inotify_user_setup);
|