[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_PATH):
			if ((old->path.mnt == new->path.mnt) &&
			    (old->path.dentry == new->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);
	BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);

	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 fanotify_should_send_event(struct fsnotify_group *group,
				       struct inode *to_tell,
				       struct fsnotify_mark *inode_mark,
				       struct fsnotify_mark *vfsmnt_mark,
				       __u32 event_mask, void *data, int data_type)
{
	__u32 marks_mask, marks_ignored_mask;
	struct path *path = data;

	pr_debug("%s: group=%p to_tell=%p inode_mark=%p vfsmnt_mark=%p "
		 "mask=%x data=%p data_type=%d\n", __func__, group, to_tell,
		 inode_mark, vfsmnt_mark, event_mask, data, data_type);

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

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

	if (inode_mark && vfsmnt_mark) {
		marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
		marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
	} else if (inode_mark) {
		/*
		 * if the event is for a child and this inode doesn't care about
		 * events on the child, don't send it!
		 */
		if ((event_mask & FS_EVENT_ON_CHILD) &&
		    !(inode_mark->mask & FS_EVENT_ON_CHILD))
			return false;
		marks_mask = inode_mark->mask;
		marks_ignored_mask = inode_mark->ignored_mask;
	} else if (vfsmnt_mark) {
		marks_mask = vfsmnt_mark->mask;
		marks_ignored_mask = vfsmnt_mark->ignored_mask;
	} else {
		BUG();
	}

	if (S_ISDIR(path->dentry->d_inode->i_mode) &&
	    (marks_ignored_mask & FS_ISDIR))
		return false;

	if (event_mask & marks_mask & ~marks_ignored_mask)
		return true;

	return false;
}

static void fanotify_free_group_priv(struct fsnotify_group *group)
{
	struct user_struct *user;

	user = group->fanotify_data.user;
	atomic_dec(&user->fanotify_listeners);
	free_uid(user);
}

const struct fsnotify_ops fanotify_fsnotify_ops = {
	.handle_event = fanotify_handle_event,
	.should_send_event = fanotify_should_send_event,
	.free_group_priv = fanotify_free_group_priv,
	.free_event_priv = NULL,
	.freeing_mark = NULL,
};
Commit	Line	Data
33d3dfff	1	#include <linux/fanotify.h>
ff0b16a9 EP	2	#include <linux/fdtable.h>
	3	#include <linux/fsnotify_backend.h>
	4	#include <linux/init.h>
9e66e423	5	#include <linux/jiffies.h>
ff0b16a9	6	#include <linux/kernel.h> /* UINT_MAX */
1c529063	7	#include <linux/mount.h>
9e66e423	8	#include <linux/sched.h>
ff0b16a9	9	#include <linux/types.h>
9e66e423	10	#include <linux/wait.h>
ff0b16a9	11
767cd46c EP	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
32c32632 AG	16	if (old->to_tell == new->to_tell &&
	17	old->data_type == new->data_type &&
	18	old->tgid == new->tgid) {
767cd46c	19	switch (old->data_type) {
2069601b LT	20	case (FSNOTIFY_EVENT_PATH):
	21	if ((old->path.mnt == new->path.mnt) &&
	22	(old->path.dentry == new->path.dentry))
767cd46c EP	23	return true;
	24	case (FSNOTIFY_EVENT_NONE):
	25	return true;
	26	default:
	27	BUG();
	28	};
	29	}
	30	return false;
	31	}
	32
f70ab54c EP	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)
767cd46c	36	{
a12a7dd3	37	struct fsnotify_event_holder *test_holder;
f70ab54c	38	struct fsnotify_event *test_event = NULL;
a12a7dd3	39	struct fsnotify_event *new_event;
767cd46c EP	40
	41	pr_debug("%s: list=%p event=%p\n", __func__, list, event);
	42
767cd46c	43
a12a7dd3	44	list_for_each_entry_reverse(test_holder, list, event_list) {
f70ab54c EP	45	if (should_merge(test_holder->event, event)) {
f70ab54c EP	46	test_event = test_holder->event;
a12a7dd3 EP	47	break;
	48	}
	49	}
f70ab54c EP	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;
767cd46c EP	85	}
767cd46c EP	86
9e66e423 EP	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
b2d87909 EP	110	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
	111	group, event, ret);
	112
9e66e423 EP	113	return ret;
	114	}
	115	#endif
	116
3a9b16b4	117	static int fanotify_handle_event(struct fsnotify_group *group,
ce8f76fb EP	118	struct fsnotify_mark *inode_mark,
ce8f76fb EP	119	struct fsnotify_mark *fanotify_mark,
3a9b16b4	120	struct fsnotify_event *event)
ff0b16a9	121	{
f70ab54c	122	int ret = 0;
9e66e423	123	struct fsnotify_event *notify_event = NULL;
ff0b16a9 EP	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);
9e66e423 EP	132	BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
9e66e423 EP	133	BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
8fcd6528	134	BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
ff0b16a9 EP	135
	136	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
	137
f70ab54c EP	138	notify_event = fsnotify_add_notify_event(group, event, NULL, fanotify_merge);
	139	if (IS_ERR(notify_event))
	140	return PTR_ERR(notify_event);
9e66e423 EP	141
	142	#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
	143	if (event->mask & FAN_ALL_PERM_EVENTS) {
	144	/* if we merged we need to wait on the new event */
	145	if (notify_event)
	146	event = notify_event;
	147	ret = fanotify_get_response_from_access(group, event);
	148	}
	149	#endif
	150
9e66e423 EP	151	if (notify_event)
9e66e423 EP	152	fsnotify_put_event(notify_event);
f70ab54c	153
ff0b16a9 EP	154	return ret;
	155	}
	156
ce8f76fb EP	157	static bool fanotify_should_send_event(struct fsnotify_group *group,
ce8f76fb EP	158	struct inode *to_tell,
ce8f76fb	159	struct fsnotify_mark *inode_mark,
1968f5ee EP	160	struct fsnotify_mark *vfsmnt_mark,
1968f5ee EP	161	__u32 event_mask, void *data, int data_type)
1c529063	162	{
1968f5ee	163	__u32 marks_mask, marks_ignored_mask;
e1c048ba	164	struct path *path = data;
1968f5ee EP	165
	166	pr_debug("%s: group=%p to_tell=%p inode_mark=%p vfsmnt_mark=%p "
	167	"mask=%x data=%p data_type=%d\n", __func__, group, to_tell,
	168	inode_mark, vfsmnt_mark, event_mask, data, data_type);
	169
1c529063	170	/* if we don't have enough info to send an event to userspace say no */
2069601b	171	if (data_type != FSNOTIFY_EVENT_PATH)
1c529063 EP	172	return false;
1c529063 EP	173
e1c048ba EP	174	/* sorry, fanotify only gives a damn about files and dirs */
	175	if (!S_ISREG(path->dentry->d_inode->i_mode) &&
	176	!S_ISDIR(path->dentry->d_inode->i_mode))
	177	return false;
	178
1968f5ee EP	179	if (inode_mark && vfsmnt_mark) {
	180	marks_mask = (vfsmnt_mark->mask \| inode_mark->mask);
	181	marks_ignored_mask = (vfsmnt_mark->ignored_mask \| inode_mark->ignored_mask);
	182	} else if (inode_mark) {
	183	/*
	184	* if the event is for a child and this inode doesn't care about
	185	* events on the child, don't send it!
	186	*/
	187	if ((event_mask & FS_EVENT_ON_CHILD) &&
	188	!(inode_mark->mask & FS_EVENT_ON_CHILD))
	189	return false;
	190	marks_mask = inode_mark->mask;
	191	marks_ignored_mask = inode_mark->ignored_mask;
	192	} else if (vfsmnt_mark) {
	193	marks_mask = vfsmnt_mark->mask;
	194	marks_ignored_mask = vfsmnt_mark->ignored_mask;
	195	} else {
	196	BUG();
	197	}
	198
8fcd6528 EP	199	if (S_ISDIR(path->dentry->d_inode->i_mode) &&
	200	(marks_ignored_mask & FS_ISDIR))
	201	return false;
	202
1968f5ee EP	203	if (event_mask & marks_mask & ~marks_ignored_mask)
	204	return true;
	205
	206	return false;
1c529063 EP	207	}
1c529063 EP	208
4afeff85 EP	209	static void fanotify_free_group_priv(struct fsnotify_group *group)
	210	{
	211	struct user_struct *user;
	212
	213	user = group->fanotify_data.user;
	214	atomic_dec(&user->fanotify_listeners);
	215	free_uid(user);
	216	}
	217
ff0b16a9 EP	218	const struct fsnotify_ops fanotify_fsnotify_ops = {
	219	.handle_event = fanotify_handle_event,
	220	.should_send_event = fanotify_should_send_event,
4afeff85	221	.free_group_priv = fanotify_free_group_priv,
ff0b16a9 EP	222	.free_event_priv = NULL,
	223	.freeing_mark = NULL,
	224	};