[net-next-2.6.git] / fs / notify / fanotify / fanotify.c

#include <linux/fanotify.h>
#include <linux/fdtable.h>
#include <linux/fsnotify_backend.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h> /* UINT_MAX */
#include <linux/mount.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/wait.h>

static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new)
{
	pr_debug("%s: old=%p new=%p\n", __func__, old, new);

	if (old->to_tell == new->to_tell &&
	    old->data_type == new->data_type &&
	    old->tgid == new->tgid) {
		switch (old->data_type) {
		case (FSNOTIFY_EVENT_FILE):
			if ((old->file->f_path.mnt == new->file->f_path.mnt) &&
			    (old->file->f_path.dentry == new->file->f_path.dentry))
				return true;
		case (FSNOTIFY_EVENT_NONE):
			return true;
		default:
			BUG();
		};
	}
	return false;
}

/* and the list better be locked by something too! */
static struct fsnotify_event *fanotify_merge(struct list_head *list,
					     struct fsnotify_event *event)
{
	struct fsnotify_event_holder *test_holder;
	struct fsnotify_event *test_event = NULL;
	struct fsnotify_event *new_event;

	pr_debug("%s: list=%p event=%p\n", __func__, list, event);


	list_for_each_entry_reverse(test_holder, list, event_list) {
		if (should_merge(test_holder->event, event)) {
			test_event = test_holder->event;
			break;
		}
	}

	if (!test_event)
		return NULL;

	fsnotify_get_event(test_event);

	/* if they are exactly the same we are done */
	if (test_event->mask == event->mask)
		return test_event;

	/*
	 * if the refcnt == 2 this is the only queue
	 * for this event and so we can update the mask
	 * in place.
	 */
	if (atomic_read(&test_event->refcnt) == 2) {
		test_event->mask |= event->mask;
		return test_event;
	}

	new_event = fsnotify_clone_event(test_event);

	/* done with test_event */
	fsnotify_put_event(test_event);

	/* couldn't allocate memory, merge was not possible */
	if (unlikely(!new_event))
		return ERR_PTR(-ENOMEM);

	/* build new event and replace it on the list */
	new_event->mask = (test_event->mask | event->mask);
	fsnotify_replace_event(test_holder, new_event);

	/* we hold a reference on new_event from clone_event */
	return new_event;
}

#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
static int fanotify_get_response_from_access(struct fsnotify_group *group,
					     struct fsnotify_event *event)
{
	int ret;

	pr_debug("%s: group=%p event=%p\n", __func__, group, event);

	wait_event(group->fanotify_data.access_waitq, event->response);

	/* userspace responded, convert to something usable */
	spin_lock(&event->lock);
	switch (event->response) {
	case FAN_ALLOW:
		ret = 0;
		break;
	case FAN_DENY:
	default:
		ret = -EPERM;
	}
	event->response = 0;
	spin_unlock(&event->lock);

	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
		 group, event, ret);
	
	return ret;
}
#endif

static int fanotify_handle_event(struct fsnotify_group *group,
				 struct fsnotify_mark *inode_mark,
				 struct fsnotify_mark *fanotify_mark,
				 struct fsnotify_event *event)
{
	int ret = 0;
	struct fsnotify_event *notify_event = NULL;

	BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
	BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
	BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
	BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
	BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
	BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
	BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
	BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
	BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);

	pr_debug("%s: group=%p event=%p\n", __func__, group, event);

	notify_event = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
	if (IS_ERR(notify_event))
		return PTR_ERR(notify_event);

#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
	if (event->mask & FAN_ALL_PERM_EVENTS) {
		/* if we merged we need to wait on the new event */
		if (notify_event)
			event = notify_event;
		ret = fanotify_get_response_from_access(group, event);
	}
#endif

	if (notify_event)
		fsnotify_put_event(notify_event);

	return ret;
}

static bool should_send_vfsmount_event(struct fsnotify_group *group,
				       struct vfsmount *mnt,
				       struct inode *inode,
				       struct fsnotify_mark *mnt_mark,
				       __u32 mask)
{
	struct fsnotify_mark *inode_mark;

	pr_debug("%s: group=%p vfsmount=%p mark=%p mask=%x\n",
		 __func__, group, mnt, mnt_mark, mask);

	mask &= mnt_mark->mask;
	mask &= ~mnt_mark->ignored_mask;

	if (mask) {
		inode_mark = fsnotify_find_inode_mark(group, inode);
		if (inode_mark) {
			mask &= ~inode_mark->ignored_mask;
			fsnotify_put_mark(inode_mark);
		}
	}

	return mask;
}

static bool should_send_inode_event(struct fsnotify_group *group,
				    struct inode *inode,
				    struct fsnotify_mark *mark,
				    __u32 mask)
{
	pr_debug("%s: group=%p inode=%p mark=%p mask=%x\n",
		 __func__, group, inode, mark, mask);

	/*
	 * if the event is for a child and this inode doesn't care about
	 * events on the child, don't send it!
	 */
	if ((mask & FS_EVENT_ON_CHILD) &&
	    !(mark->mask & FS_EVENT_ON_CHILD))
		return false;
	else
		return true;
}

static bool fanotify_should_send_event(struct fsnotify_group *group,
				       struct inode *to_tell,
				       struct vfsmount *mnt,
				       struct fsnotify_mark *inode_mark,
				       struct fsnotify_mark *vfsmount_mark,
				       __u32 mask, void *data, int data_type)
{
	pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x data=%p data_type=%d\n",
		 __func__, group, to_tell, mnt, mask, data, data_type);

	/* sorry, fanotify only gives a damn about files and dirs */
	if (!S_ISREG(to_tell->i_mode) &&
	    !S_ISDIR(to_tell->i_mode))
		return false;

	/* if we don't have enough info to send an event to userspace say no */
	if (data_type != FSNOTIFY_EVENT_FILE)
		return false;

	if (mnt)
		return should_send_vfsmount_event(group, mnt, to_tell,
						  vfsmount_mark, mask);
	else
		return should_send_inode_event(group, to_tell, inode_mark, mask);
}

const struct fsnotify_ops fanotify_fsnotify_ops = {
	.handle_event = fanotify_handle_event,
	.should_send_event = fanotify_should_send_event,
	.free_group_priv = NULL,
	.free_event_priv = NULL,
	.freeing_mark = NULL,
};
Commit	Line	Data
	1	#include <linux/fanotify.h>
	2	#include <linux/fdtable.h>
	3	#include <linux/fsnotify_backend.h>
	4	#include <linux/init.h>
	5	#include <linux/jiffies.h>
	6	#include <linux/kernel.h> /* UINT_MAX */
	7	#include <linux/mount.h>
	8	#include <linux/sched.h>
	9	#include <linux/types.h>
	10	#include <linux/wait.h>
	11
	12	static bool should_merge(struct fsnotify_event old, struct fsnotify_event new)
	13	{
	14	pr_debug("%s: old=%p new=%p\n", __func__, old, new);
	15
	16	if (old->to_tell == new->to_tell &&
	17	old->data_type == new->data_type &&
	18	old->tgid == new->tgid) {
	19	switch (old->data_type) {
	20	case (FSNOTIFY_EVENT_FILE):
	21	if ((old->file->f_path.mnt == new->file->f_path.mnt) &&
	22	(old->file->f_path.dentry == new->file->f_path.dentry))
	23	return true;
	24	case (FSNOTIFY_EVENT_NONE):
	25	return true;
	26	default:
	27	BUG();
	28	};
	29	}
	30	return false;
	31	}
	32
	33	/* and the list better be locked by something too! */
	34	static struct fsnotify_event fanotify_merge(struct list_head list,
	35	struct fsnotify_event *event)
	36	{
	37	struct fsnotify_event_holder *test_holder;
	38	struct fsnotify_event *test_event = NULL;
	39	struct fsnotify_event *new_event;
	40
	41	pr_debug("%s: list=%p event=%p\n", __func__, list, event);
	42
	43
	44	list_for_each_entry_reverse(test_holder, list, event_list) {
	45	if (should_merge(test_holder->event, event)) {
	46	test_event = test_holder->event;
	47	break;
	48	}
	49	}
	50
	51	if (!test_event)
	52	return NULL;
	53
	54	fsnotify_get_event(test_event);
	55
	56	/* if they are exactly the same we are done */
	57	if (test_event->mask == event->mask)
	58	return test_event;
	59
	60	/*
	61	* if the refcnt == 2 this is the only queue
	62	* for this event and so we can update the mask
	63	* in place.
	64	*/
	65	if (atomic_read(&test_event->refcnt) == 2) {
	66	test_event->mask \|= event->mask;
	67	return test_event;
	68	}
	69
	70	new_event = fsnotify_clone_event(test_event);
	71
	72	/* done with test_event */
	73	fsnotify_put_event(test_event);
	74
	75	/* couldn't allocate memory, merge was not possible */
	76	if (unlikely(!new_event))
	77	return ERR_PTR(-ENOMEM);
	78
	79	/* build new event and replace it on the list */
	80	new_event->mask = (test_event->mask \| event->mask);
	81	fsnotify_replace_event(test_holder, new_event);
	82
	83	/* we hold a reference on new_event from clone_event */
	84	return new_event;
	85	}
	86
	87	#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
	88	static int fanotify_get_response_from_access(struct fsnotify_group *group,
	89	struct fsnotify_event *event)
	90	{
	91	int ret;
	92
	93	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
	94
	95	wait_event(group->fanotify_data.access_waitq, event->response);
	96
	97	/* userspace responded, convert to something usable */
	98	spin_lock(&event->lock);
	99	switch (event->response) {
	100	case FAN_ALLOW:
	101	ret = 0;
	102	break;
	103	case FAN_DENY:
	104	default:
	105	ret = -EPERM;
	106	}
	107	event->response = 0;
	108	spin_unlock(&event->lock);
	109
	110	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
	111	group, event, ret);
	112
	113	return ret;
	114	}
	115	#endif
	116
	117	static int fanotify_handle_event(struct fsnotify_group *group,
	118	struct fsnotify_mark *inode_mark,
	119	struct fsnotify_mark *fanotify_mark,
	120	struct fsnotify_event *event)
	121	{
	122	int ret = 0;
	123	struct fsnotify_event *notify_event = NULL;
	124
	125	BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
	126	BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
	127	BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
	128	BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
	129	BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
	130	BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
	131	BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
	132	BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
	133	BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
	134
	135	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
	136
	137	notify_event = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
	138	if (IS_ERR(notify_event))
	139	return PTR_ERR(notify_event);
	140
	141	#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
	142	if (event->mask & FAN_ALL_PERM_EVENTS) {
	143	/* if we merged we need to wait on the new event */
	144	if (notify_event)
	145	event = notify_event;
	146	ret = fanotify_get_response_from_access(group, event);
	147	}
	148	#endif
	149
	150	if (notify_event)
	151	fsnotify_put_event(notify_event);
	152
	153	return ret;
	154	}
	155
	156	static bool should_send_vfsmount_event(struct fsnotify_group *group,
	157	struct vfsmount *mnt,
	158	struct inode *inode,
	159	struct fsnotify_mark *mnt_mark,
	160	__u32 mask)
	161	{
	162	struct fsnotify_mark *inode_mark;
	163
	164	pr_debug("%s: group=%p vfsmount=%p mark=%p mask=%x\n",
	165	__func__, group, mnt, mnt_mark, mask);
	166
	167	mask &= mnt_mark->mask;
	168	mask &= ~mnt_mark->ignored_mask;
	169
	170	if (mask) {
	171	inode_mark = fsnotify_find_inode_mark(group, inode);
	172	if (inode_mark) {
	173	mask &= ~inode_mark->ignored_mask;
	174	fsnotify_put_mark(inode_mark);
	175	}
	176	}
	177
	178	return mask;
	179	}
	180
	181	static bool should_send_inode_event(struct fsnotify_group *group,
	182	struct inode *inode,
	183	struct fsnotify_mark *mark,
	184	__u32 mask)
	185	{
	186	pr_debug("%s: group=%p inode=%p mark=%p mask=%x\n",
	187	__func__, group, inode, mark, mask);
	188
	189	/*
	190	* if the event is for a child and this inode doesn't care about
	191	* events on the child, don't send it!
	192	*/
	193	if ((mask & FS_EVENT_ON_CHILD) &&
	194	!(mark->mask & FS_EVENT_ON_CHILD))
	195	return false;
	196	else
	197	return true;
	198	}
	199
	200	static bool fanotify_should_send_event(struct fsnotify_group *group,
	201	struct inode *to_tell,
	202	struct vfsmount *mnt,
	203	struct fsnotify_mark *inode_mark,
	204	struct fsnotify_mark *vfsmount_mark,
	205	__u32 mask, void *data, int data_type)
	206	{
	207	pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x data=%p data_type=%d\n",
	208	__func__, group, to_tell, mnt, mask, data, data_type);
	209
	210	/* sorry, fanotify only gives a damn about files and dirs */
	211	if (!S_ISREG(to_tell->i_mode) &&
	212	!S_ISDIR(to_tell->i_mode))
	213	return false;
	214
	215	/* if we don't have enough info to send an event to userspace say no */
	216	if (data_type != FSNOTIFY_EVENT_FILE)
	217	return false;
	218
	219	if (mnt)
	220	return should_send_vfsmount_event(group, mnt, to_tell,
	221	vfsmount_mark, mask);
	222	else
	223	return should_send_inode_event(group, to_tell, inode_mark, mask);
	224	}
	225
	226	const struct fsnotify_ops fanotify_fsnotify_ops = {
	227	.handle_event = fanotify_handle_event,
	228	.should_send_event = fanotify_should_send_event,
	229	.free_group_priv = NULL,
	230	.free_event_priv = NULL,
	231	.freeing_mark = NULL,
	232	};