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c2fd68b6b2
Various filesystems rely on the lookup_one_len() helper to lookup a single path component relative to a well-known starting point. Allow such filesystems to support idmapped mounts by adding a version of this helper to take the idmap into account when calling inode_permission(). This change is a required to let btrfs (and other filesystems) support idmapped mounts. Cc: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: David Sterba <dsterba@suse.com>
103 lines
3.8 KiB
C
103 lines
3.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_NAMEI_H
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#define _LINUX_NAMEI_H
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#include <linux/fs.h>
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#include <linux/kernel.h>
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#include <linux/path.h>
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#include <linux/fcntl.h>
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#include <linux/errno.h>
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enum { MAX_NESTED_LINKS = 8 };
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#define MAXSYMLINKS 40
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/*
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* Type of the last component on LOOKUP_PARENT
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*/
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enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT};
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/* pathwalk mode */
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#define LOOKUP_FOLLOW 0x0001 /* follow links at the end */
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#define LOOKUP_DIRECTORY 0x0002 /* require a directory */
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#define LOOKUP_AUTOMOUNT 0x0004 /* force terminal automount */
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#define LOOKUP_EMPTY 0x4000 /* accept empty path [user_... only] */
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#define LOOKUP_DOWN 0x8000 /* follow mounts in the starting point */
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#define LOOKUP_MOUNTPOINT 0x0080 /* follow mounts in the end */
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#define LOOKUP_REVAL 0x0020 /* tell ->d_revalidate() to trust no cache */
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#define LOOKUP_RCU 0x0040 /* RCU pathwalk mode; semi-internal */
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/* These tell filesystem methods that we are dealing with the final component... */
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#define LOOKUP_OPEN 0x0100 /* ... in open */
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#define LOOKUP_CREATE 0x0200 /* ... in object creation */
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#define LOOKUP_EXCL 0x0400 /* ... in exclusive creation */
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#define LOOKUP_RENAME_TARGET 0x0800 /* ... in destination of rename() */
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/* internal use only */
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#define LOOKUP_PARENT 0x0010
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/* Scoping flags for lookup. */
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#define LOOKUP_NO_SYMLINKS 0x010000 /* No symlink crossing. */
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#define LOOKUP_NO_MAGICLINKS 0x020000 /* No nd_jump_link() crossing. */
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#define LOOKUP_NO_XDEV 0x040000 /* No mountpoint crossing. */
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#define LOOKUP_BENEATH 0x080000 /* No escaping from starting point. */
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#define LOOKUP_IN_ROOT 0x100000 /* Treat dirfd as fs root. */
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#define LOOKUP_CACHED 0x200000 /* Only do cached lookup */
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/* LOOKUP_* flags which do scope-related checks based on the dirfd. */
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#define LOOKUP_IS_SCOPED (LOOKUP_BENEATH | LOOKUP_IN_ROOT)
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extern int path_pts(struct path *path);
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extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
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static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
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struct path *path)
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{
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return user_path_at_empty(dfd, name, flags, path, NULL);
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}
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extern int kern_path(const char *, unsigned, struct path *);
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extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
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extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
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extern void done_path_create(struct path *, struct dentry *);
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extern struct dentry *kern_path_locked(const char *, struct path *);
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extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
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extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
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extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
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extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
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struct dentry *lookup_one(struct user_namespace *, const char *, struct dentry *, int);
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extern int follow_down_one(struct path *);
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extern int follow_down(struct path *);
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extern int follow_up(struct path *);
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extern struct dentry *lock_rename(struct dentry *, struct dentry *);
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extern void unlock_rename(struct dentry *, struct dentry *);
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extern int __must_check nd_jump_link(struct path *path);
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static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
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{
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((char *) name)[min(len, maxlen)] = '\0';
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}
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/**
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* retry_estale - determine whether the caller should retry an operation
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* @error: the error that would currently be returned
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* @flags: flags being used for next lookup attempt
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*
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* Check to see if the error code was -ESTALE, and then determine whether
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* to retry the call based on whether "flags" already has LOOKUP_REVAL set.
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*
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* Returns true if the caller should try the operation again.
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*/
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static inline bool
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retry_estale(const long error, const unsigned int flags)
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{
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return error == -ESTALE && !(flags & LOOKUP_REVAL);
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}
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#endif /* _LINUX_NAMEI_H */
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