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linux-stable/include/linux/fsnotify.h
Amir Goldstein 9e2ba2c34f fanotify: send FAN_DIR_MODIFY event flavor with dir inode and name 
Dirent events are going to be supported in two flavors:

1. Directory fid info + mask that includes the specific event types
   (e.g. FAN_CREATE) and an optional FAN_ONDIR flag.
2. Directory fid info + name + mask that includes only FAN_DIR_MODIFY.

To request the second event flavor, user needs to set the event type
FAN_DIR_MODIFY in the mark mask.

The first flavor is supported since kernel v5.1 for groups initialized
with flag FAN_REPORT_FID.  It is intended to be used for watching
directories in "batch mode" - the watcher is notified when directory is
changed and re-scans the directory content in response.  This event
flavor is stored more compactly in the event queue, so it is optimal
for workloads with frequent directory changes.

The second event flavor is intended to be used for watching large
directories, where the cost of re-scan of the directory on every change
is considered too high.  The watcher getting the event with the directory
fid and entry name is expected to call fstatat(2) to query the content of
the entry after the change.

Legacy inotify events are reported with name and event mask (e.g. "foo",
FAN_CREATE | FAN_ONDIR).  That can lead users to the conclusion that
there is *currently* an entry "foo" that is a sub-directory, when in fact
"foo" may be negative or non-dir by the time user gets the event.

To make it clear that the current state of the named entry is unknown,
when reporting an event with name info, fanotify obfuscates the specific
event types (e.g. create,delete,rename) and uses a common event type -
FAN_DIR_MODIFY to describe the change.  This should make it harder for
users to make wrong assumptions and write buggy filesystem monitors.

At this point, name info reporting is not yet implemented, so trying to
set FAN_DIR_MODIFY in mark mask will return -EINVAL.

Link: https://lore.kernel.org/r/20200319151022.31456-12-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2020-03-25 10:27:16 +01:00

322 lines
7.7 KiB
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_FS_NOTIFY_H
#define _LINUX_FS_NOTIFY_H
/*
* include/linux/fsnotify.h - generic hooks for filesystem notification, to
* reduce in-source duplication from both dnotify and inotify.
*
* We don't compile any of this away in some complicated menagerie of ifdefs.
* Instead, we rely on the code inside to optimize away as needed.
*
* (C) Copyright 2005 Robert Love
*/
#include <linux/fsnotify_backend.h>
#include <linux/audit.h>
#include <linux/slab.h>
#include <linux/bug.h>
/*
* Notify this @dir inode about a change in a child directory entry.
* The directory entry may have turned positive or negative or its inode may
* have changed (i.e. renamed over).
*
* Unlike fsnotify_parent(), the event will be reported regardless of the
* FS_EVENT_ON_CHILD mask on the parent inode.
*/
static inline void fsnotify_name(struct inode *dir, __u32 mask,
struct inode *child,
const struct qstr *name, u32 cookie)
{
fsnotify(dir, mask, child, FSNOTIFY_EVENT_INODE, name, cookie);
/*
* Send another flavor of the event without child inode data and
* without the specific event type (e.g. FS_CREATE|FS_IS_DIR).
* The name is relative to the dir inode the event is reported to.
*/
fsnotify(dir, FS_DIR_MODIFY, dir, FSNOTIFY_EVENT_INODE, name, 0);
}
static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
__u32 mask)
{
fsnotify_name(dir, mask, d_inode(dentry), &dentry->d_name, 0);
}
/*
* Simple wrappers to consolidate calls fsnotify_parent()/fsnotify() when
* an event is on a file/dentry.
*/
static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
{
struct inode *inode = d_inode(dentry);
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
fsnotify_parent(dentry, mask, inode, FSNOTIFY_EVENT_INODE);
fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
}
static inline int fsnotify_file(struct file *file, __u32 mask)
{
const struct path *path = &file->f_path;
struct inode *inode = file_inode(file);
int ret;
if (file->f_mode & FMODE_NONOTIFY)
return 0;
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
ret = fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH);
if (ret)
return ret;
return fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
}
/* Simple call site for access decisions */
static inline int fsnotify_perm(struct file *file, int mask)
{
int ret;
__u32 fsnotify_mask = 0;
if (!(mask & (MAY_READ | MAY_OPEN)))
return 0;
if (mask & MAY_OPEN) {
fsnotify_mask = FS_OPEN_PERM;
if (file->f_flags & __FMODE_EXEC) {
ret = fsnotify_file(file, FS_OPEN_EXEC_PERM);
if (ret)
return ret;
}
} else if (mask & MAY_READ) {
fsnotify_mask = FS_ACCESS_PERM;
}
return fsnotify_file(file, fsnotify_mask);
}
/*
* fsnotify_link_count - inode's link count changed
*/
static inline void fsnotify_link_count(struct inode *inode)
{
__u32 mask = FS_ATTRIB;
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
}
/*
* fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
*/
static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
const struct qstr *old_name,
int isdir, struct inode *target,
struct dentry *moved)
{
struct inode *source = moved->d_inode;
u32 fs_cookie = fsnotify_get_cookie();
__u32 old_dir_mask = FS_MOVED_FROM;
__u32 new_dir_mask = FS_MOVED_TO;
__u32 mask = FS_MOVE_SELF;
const struct qstr *new_name = &moved->d_name;
if (old_dir == new_dir)
old_dir_mask |= FS_DN_RENAME;
if (isdir) {
old_dir_mask |= FS_ISDIR;
new_dir_mask |= FS_ISDIR;
mask |= FS_ISDIR;
}
fsnotify_name(old_dir, old_dir_mask, source, old_name, fs_cookie);
fsnotify_name(new_dir, new_dir_mask, source, new_name, fs_cookie);
if (target)
fsnotify_link_count(target);
if (source)
fsnotify(source, mask, source, FSNOTIFY_EVENT_INODE, NULL, 0);
audit_inode_child(new_dir, moved, AUDIT_TYPE_CHILD_CREATE);
}
/*
* fsnotify_inode_delete - and inode is being evicted from cache, clean up is needed
*/
static inline void fsnotify_inode_delete(struct inode *inode)
{
__fsnotify_inode_delete(inode);
}
/*
* fsnotify_vfsmount_delete - a vfsmount is being destroyed, clean up is needed
*/
static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt)
{
__fsnotify_vfsmount_delete(mnt);
}
/*
* fsnotify_inoderemove - an inode is going away
*/
static inline void fsnotify_inoderemove(struct inode *inode)
{
__u32 mask = FS_DELETE_SELF;
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
__fsnotify_inode_delete(inode);
}
/*
* fsnotify_create - 'name' was linked in
*/
static inline void fsnotify_create(struct inode *inode, struct dentry *dentry)
{
audit_inode_child(inode, dentry, AUDIT_TYPE_CHILD_CREATE);
fsnotify_dirent(inode, dentry, FS_CREATE);
}
/*
* fsnotify_link - new hardlink in 'inode' directory
* Note: We have to pass also the linked inode ptr as some filesystems leave
* new_dentry->d_inode NULL and instantiate inode pointer later
*/
static inline void fsnotify_link(struct inode *dir, struct inode *inode,
struct dentry *new_dentry)
{
fsnotify_link_count(inode);
audit_inode_child(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
fsnotify_name(dir, FS_CREATE, inode, &new_dentry->d_name, 0);
}
/*
* fsnotify_unlink - 'name' was unlinked
*
* Caller must make sure that dentry->d_name is stable.
*/
static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
{
/* Expected to be called before d_delete() */
WARN_ON_ONCE(d_is_negative(dentry));
fsnotify_dirent(dir, dentry, FS_DELETE);
}
/*
* fsnotify_mkdir - directory 'name' was created
*/
static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)
{
audit_inode_child(inode, dentry, AUDIT_TYPE_CHILD_CREATE);
fsnotify_dirent(inode, dentry, FS_CREATE | FS_ISDIR);
}
/*
* fsnotify_rmdir - directory 'name' was removed
*
* Caller must make sure that dentry->d_name is stable.
*/
static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
{
/* Expected to be called before d_delete() */
WARN_ON_ONCE(d_is_negative(dentry));
fsnotify_dirent(dir, dentry, FS_DELETE | FS_ISDIR);
}
/*
* fsnotify_access - file was read
*/
static inline void fsnotify_access(struct file *file)
{
fsnotify_file(file, FS_ACCESS);
}
/*
* fsnotify_modify - file was modified
*/
static inline void fsnotify_modify(struct file *file)
{
fsnotify_file(file, FS_MODIFY);
}
/*
* fsnotify_open - file was opened
*/
static inline void fsnotify_open(struct file *file)
{
__u32 mask = FS_OPEN;
if (file->f_flags & __FMODE_EXEC)
mask |= FS_OPEN_EXEC;
fsnotify_file(file, mask);
}
/*
* fsnotify_close - file was closed
*/
static inline void fsnotify_close(struct file *file)
{
__u32 mask = (file->f_mode & FMODE_WRITE) ? FS_CLOSE_WRITE :
FS_CLOSE_NOWRITE;
fsnotify_file(file, mask);
}
/*
* fsnotify_xattr - extended attributes were changed
*/
static inline void fsnotify_xattr(struct dentry *dentry)
{
fsnotify_dentry(dentry, FS_ATTRIB);
}
/*
* fsnotify_change - notify_change event. file was modified and/or metadata
* was changed.
*/
static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
{
__u32 mask = 0;
if (ia_valid & ATTR_UID)
mask |= FS_ATTRIB;
if (ia_valid & ATTR_GID)
mask |= FS_ATTRIB;
if (ia_valid & ATTR_SIZE)
mask |= FS_MODIFY;
/* both times implies a utime(s) call */
if ((ia_valid & (ATTR_ATIME | ATTR_MTIME)) == (ATTR_ATIME | ATTR_MTIME))
mask |= FS_ATTRIB;
else if (ia_valid & ATTR_ATIME)
mask |= FS_ACCESS;
else if (ia_valid & ATTR_MTIME)
mask |= FS_MODIFY;
if (ia_valid & ATTR_MODE)
mask |= FS_ATTRIB;
if (mask)
fsnotify_dentry(dentry, mask);
}
#endif /* _LINUX_FS_NOTIFY_H */
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