Commit 870499bc authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fanotify: report file range info with pre-content events 



With group class FAN_CLASS_PRE_CONTENT, report offset and length info
along with FAN_PRE_ACCESS pre-content events.

This information is meant to be used by hierarchical storage managers
that want to fill partial content of files on first access to range.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Link: https://patch.msgid.link/b90a9e6c809dd3cad5684da90f23ea93ec6ce8c8.1731684329.git.josef@toxicpanda.com
parent 4f8afa33

fs/notify/fanotify/fanotify.h

+8 −0
Original line number Diff line number Diff line
@@ -448,6 +448,14 @@ static inline bool fanotify_is_perm_event(u32 mask) 
		mask & FANOTIFY_PERM_EVENTS;

}



static inline bool fanotify_event_has_access_range(struct fanotify_event *event)

{

	if (!(event->mask & FANOTIFY_PRE_CONTENT_EVENTS))

		return false;



	return FANOTIFY_PERM(event)->ppos;

}



static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)

{

	return container_of(fse, struct fanotify_event, fse);

fs/notify/fanotify/fanotify_user.c

+38 −0
Original line number Diff line number Diff line
@@ -121,6 +121,8 @@ struct kmem_cache *fanotify_perm_event_cachep __ro_after_init; 
	sizeof(struct fanotify_event_info_pidfd)

#define FANOTIFY_ERROR_INFO_LEN \

	(sizeof(struct fanotify_event_info_error))

#define FANOTIFY_RANGE_INFO_LEN \

	(sizeof(struct fanotify_event_info_range))



static int fanotify_fid_info_len(int fh_len, int name_len)

{
@@ -180,6 +182,9 @@ static size_t fanotify_event_len(unsigned int info_mode, 
	if (info_mode & FAN_REPORT_PIDFD)

		event_len += FANOTIFY_PIDFD_INFO_LEN;



	if (fanotify_event_has_access_range(event))

		event_len += FANOTIFY_RANGE_INFO_LEN;



	return event_len;

}
@@ -516,6 +521,30 @@ static int copy_pidfd_info_to_user(int pidfd, 
	return info_len;

}



static size_t copy_range_info_to_user(struct fanotify_event *event,

				      char __user *buf, int count)

{

	struct fanotify_perm_event *pevent = FANOTIFY_PERM(event);

	struct fanotify_event_info_range info = { };

	size_t info_len = FANOTIFY_RANGE_INFO_LEN;



	if (WARN_ON_ONCE(info_len > count))

		return -EFAULT;



	if (WARN_ON_ONCE(!pevent->ppos))

		return -EINVAL;



	info.hdr.info_type = FAN_EVENT_INFO_TYPE_RANGE;

	info.hdr.len = info_len;

	info.offset = *(pevent->ppos);

	info.count = pevent->count;



	if (copy_to_user(buf, &info, info_len))

		return -EFAULT;



	return info_len;

}



static int copy_info_records_to_user(struct fanotify_event *event,

				     struct fanotify_info *info,

				     unsigned int info_mode, int pidfd,
@@ -637,6 +666,15 @@ static int copy_info_records_to_user(struct fanotify_event *event, 
		total_bytes += ret;

	}



	if (fanotify_event_has_access_range(event)) {

		ret = copy_range_info_to_user(event, buf, count);

		if (ret < 0)

			return ret;

		buf += ret;

		count -= ret;

		total_bytes += ret;

	}



	return total_bytes;

}

include/uapi/linux/fanotify.h

+8 −0
Original line number Diff line number Diff line
@@ -146,6 +146,7 @@ struct fanotify_event_metadata { 
#define FAN_EVENT_INFO_TYPE_DFID	3

#define FAN_EVENT_INFO_TYPE_PIDFD	4

#define FAN_EVENT_INFO_TYPE_ERROR	5

#define FAN_EVENT_INFO_TYPE_RANGE	6



/* Special info types for FAN_RENAME */

#define FAN_EVENT_INFO_TYPE_OLD_DFID_NAME	10
@@ -192,6 +193,13 @@ struct fanotify_event_info_error { 
	__u32 error_count;

};



struct fanotify_event_info_range {

	struct fanotify_event_info_header hdr;

	__u32 pad;

	__u64 offset;

	__u64 count;

};



/*

 * User space may need to record additional information about its decision.

 * The extra information type records what kind of information is included.