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linux/include/linux/fsnotify.h
Amir Goldstein def3ae83da
fs: store real path instead of fake path in backing file f_path 
A backing file struct stores two path's, one "real" path that is referring
to f_inode and one "fake" path, which should be displayed to users in
/proc/<pid>/maps.

There is a lot more potential code that needs to know the "real" path, then
code that needs to know the "fake" path.

Instead of code having to request the "real" path with file_real_path(),
store the "real" path in f_path and require code that needs to know the
"fake" path request it with file_user_path().
Replace the file_real_path() helper with a simple const accessor f_path().

After this change, file_dentry() is not expected to observe any files
with overlayfs f_path and real f_inode, so the call to ->d_real() should
not be needed.  Leave the ->d_real() call for now and add an assertion
in ovl_d_real() to catch if we made wrong assumptions.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Link: https://lore.kernel.org/r/CAJfpegtt48eXhhjDFA1ojcHPNKj3Go6joryCPtEFAKpocyBsnw@mail.gmail.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231009153712.1566422-4-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-10-19 11:03:15 +02:00

397 lines
9.8 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 and will not be reported if only
* the child is interested and not the parent.
*/
static inline int fsnotify_name(__u32 mask, const void *data, int data_type,
struct inode *dir, const struct qstr *name,
u32 cookie)
{
if (atomic_long_read(&dir->i_sb->s_fsnotify_connectors) == 0)
return 0;
return fsnotify(mask, data, data_type, dir, name, NULL, cookie);
}
static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
__u32 mask)
{
fsnotify_name(mask, dentry, FSNOTIFY_EVENT_DENTRY, dir, &dentry->d_name, 0);
}
static inline void fsnotify_inode(struct inode *inode, __u32 mask)
{
if (atomic_long_read(&inode->i_sb->s_fsnotify_connectors) == 0)
return;
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
fsnotify(mask, inode, FSNOTIFY_EVENT_INODE, NULL, NULL, inode, 0);
}
/* Notify this dentry's parent about a child's events. */
static inline int fsnotify_parent(struct dentry *dentry, __u32 mask,
const void *data, int data_type)
{
struct inode *inode = d_inode(dentry);
if (atomic_long_read(&inode->i_sb->s_fsnotify_connectors) == 0)
return 0;
if (S_ISDIR(inode->i_mode)) {
mask |= FS_ISDIR;
/* sb/mount marks are not interested in name of directory */
if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
goto notify_child;
}
/* disconnected dentry cannot notify parent */
if (IS_ROOT(dentry))
goto notify_child;
return __fsnotify_parent(dentry, mask, data, data_type);
notify_child:
return fsnotify(mask, data, data_type, NULL, NULL, inode, 0);
}
/*
* Simple wrappers to consolidate calls to fsnotify_parent() when an event
* is on a file/dentry.
*/
static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask)
{
fsnotify_parent(dentry, mask, dentry, FSNOTIFY_EVENT_DENTRY);
}
static inline int fsnotify_file(struct file *file, __u32 mask)
{
const struct path *path;
if (file->f_mode & FMODE_NONOTIFY)
return 0;
path = &file->f_path;
return fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH);
}
/* 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)
{
fsnotify_inode(inode, FS_ATTRIB);
}
/*
* 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 rename_mask = FS_RENAME;
const struct qstr *new_name = &moved->d_name;
if (isdir) {
old_dir_mask |= FS_ISDIR;
new_dir_mask |= FS_ISDIR;
rename_mask |= FS_ISDIR;
}
/* Event with information about both old and new parent+name */
fsnotify_name(rename_mask, moved, FSNOTIFY_EVENT_DENTRY,
old_dir, old_name, 0);
fsnotify_name(old_dir_mask, source, FSNOTIFY_EVENT_INODE,
old_dir, old_name, fs_cookie);
fsnotify_name(new_dir_mask, source, FSNOTIFY_EVENT_INODE,
new_dir, new_name, fs_cookie);
if (target)
fsnotify_link_count(target);
fsnotify_inode(source, FS_MOVE_SELF);
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)
{
fsnotify_inode(inode, FS_DELETE_SELF);
__fsnotify_inode_delete(inode);
}
/*
* fsnotify_create - 'name' was linked in
*
* Caller must make sure that dentry->d_name is stable.
* Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
* ->d_inode later
*/
static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)
{
audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
fsnotify_dirent(dir, dentry, FS_CREATE);
}
/*
* fsnotify_link - new hardlink in 'inode' directory
*
* Caller must make sure that new_dentry->d_name is stable.
* 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(FS_CREATE, inode, FSNOTIFY_EVENT_INODE,
dir, &new_dentry->d_name, 0);
}
/*
* fsnotify_delete - @dentry was unlinked and unhashed
*
* Caller must make sure that dentry->d_name is stable.
*
* Note: unlike fsnotify_unlink(), we have to pass also the unlinked inode
* as this may be called after d_delete() and old_dentry may be negative.
*/
static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
struct dentry *dentry)
{
__u32 mask = FS_DELETE;
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
fsnotify_name(mask, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
0);
}
/**
* d_delete_notify - delete a dentry and call fsnotify_delete()
* @dentry: The dentry to delete
*
* This helper is used to guaranty that the unlinked inode cannot be found
* by lookup of this name after fsnotify_delete() event has been delivered.
*/
static inline void d_delete_notify(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
ihold(inode);
d_delete(dentry);
fsnotify_delete(dir, inode, dentry);
iput(inode);
}
/*
* 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)
{
if (WARN_ON_ONCE(d_is_negative(dentry)))
return;
fsnotify_delete(dir, d_inode(dentry), dentry);
}
/*
* fsnotify_mkdir - directory 'name' was created
*
* Caller must make sure that dentry->d_name is stable.
* Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate
* ->d_inode later
*/
static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
{
audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);
fsnotify_dirent(dir, 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)
{
if (WARN_ON_ONCE(d_is_negative(dentry)))
return;
fsnotify_delete(dir, d_inode(dentry), dentry);
}
/*
* 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);
}
static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode,
int error)
{
struct fs_error_report report = {
.error = error,
.inode = inode,
.sb = sb,
};
return fsnotify(FS_ERROR, &report, FSNOTIFY_EVENT_ERROR,
NULL, NULL, NULL, 0);
}
#endif /* _LINUX_FS_NOTIFY_H */
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