path: root/fs/overlayfs/overlayfs.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *
 * Copyright (C) 2011 Novell Inc.
 */

#include <linux/kernel.h>
#include <linux/uuid.h>
#include <linux/fs.h>
#include "ovl_entry.h"

#undef pr_fmt
#define pr_fmt(fmt) "overlayfs: " fmt

enum ovl_path_type {
	__OVL_PATH_UPPER	= (1 << 0),
	__OVL_PATH_MERGE	= (1 << 1),
	__OVL_PATH_ORIGIN	= (1 << 2),
};

#define OVL_TYPE_UPPER(type)	((type) & __OVL_PATH_UPPER)
#define OVL_TYPE_MERGE(type)	((type) & __OVL_PATH_MERGE)
#define OVL_TYPE_ORIGIN(type)	((type) & __OVL_PATH_ORIGIN)

#define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
#define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
#define OVL_XATTR_REDIRECT OVL_XATTR_PREFIX "redirect"
#define OVL_XATTR_ORIGIN OVL_XATTR_PREFIX "origin"
#define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
#define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
#define OVL_XATTR_UPPER OVL_XATTR_PREFIX "upper"
#define OVL_XATTR_METACOPY OVL_XATTR_PREFIX "metacopy"

enum ovl_inode_flag {
	/* Pure upper dir that may contain non pure upper entries */
	OVL_IMPURE,
	/* Non-merge dir that may contain whiteout entries */
	OVL_WHITEOUTS,
	OVL_INDEX,
	OVL_UPPERDATA,
	/* Inode number will remain constant over copy up. */
	OVL_CONST_INO,
};

enum ovl_entry_flag {
	OVL_E_UPPER_ALIAS,
	OVL_E_OPAQUE,
	OVL_E_CONNECTED,
};

enum {
	OVL_XINO_OFF,
	OVL_XINO_AUTO,
	OVL_XINO_ON,
};

/*
 * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
 * where:
 * origin.fh	- exported file handle of the lower file
 * origin.uuid	- uuid of the lower filesystem
 */
#define OVL_FH_VERSION	0
#define OVL_FH_MAGIC	0xfb

/* CPU byte order required for fid decoding:  */
#define OVL_FH_FLAG_BIG_ENDIAN	(1 << 0)
#define OVL_FH_FLAG_ANY_ENDIAN	(1 << 1)
/* Is the real inode encoded in fid an upper inode? */
#define OVL_FH_FLAG_PATH_UPPER	(1 << 2)

#define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN | \
			 OVL_FH_FLAG_PATH_UPPER)

#if defined(__LITTLE_ENDIAN)
#define OVL_FH_FLAG_CPU_ENDIAN 0
#elif defined(__BIG_ENDIAN)
#define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
#else
#error Endianness not defined
#endif

/* The type used to be returned by overlay exportfs for misaligned fid */
#define OVL_FILEID_V0	0xfb
/* The type returned by overlay exportfs for 32bit aligned fid */
#define OVL_FILEID_V1	0xf8

/* On-disk format for "origin" file handle */
struct ovl_fb {
	u8 version;	/* 0 */
	u8 magic;	/* 0xfb */
	u8 len;		/* size of this header + size of fid */
	u8 flags;	/* OVL_FH_FLAG_* */
	u8 type;	/* fid_type of fid */
	uuid_t uuid;	/* uuid of filesystem */
	u32 fid[];	/* file identifier should be 32bit aligned in-memory */
} __packed;

/* In-memory and on-wire format for overlay file handle */
struct ovl_fh {
	u8 padding[3];	/* make sure fb.fid is 32bit aligned */
	union {
		struct ovl_fb fb;
		u8 buf[0];
	};
} __packed;

#define OVL_FH_WIRE_OFFSET	offsetof(struct ovl_fh, fb)
#define OVL_FH_LEN(fh)		(OVL_FH_WIRE_OFFSET + (fh)->fb.len)
#define OVL_FH_FID_OFFSET	(OVL_FH_WIRE_OFFSET + \
				 offsetof(struct ovl_fb, fid))

static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
{
	int err = vfs_rmdir(dir, dentry);

	pr_debug("rmdir(%pd2) = %i\n", dentry, err);
	return err;
}

static inline int ovl_do_unlink(struct inode *dir, struct dentry *dentry)
{
	int err = vfs_unlink(dir, dentry, NULL);

	pr_debug("unlink(%pd2) = %i\n", dentry, err);
	return err;
}

static inline int ovl_do_link(struct dentry *old_dentry, struct inode *dir,
			      struct dentry *new_dentry)
{
	int err = vfs_link(old_dentry, dir, new_dentry, NULL);

	pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
	return err;
}

static inline int ovl_do_create(struct inode *dir, struct dentry *dentry,
				umode_t mode)
{
	int err = vfs_create(dir, dentry, mode, true);

	pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
	return err;
}

static inline int ovl_do_mkdir(struct inode *dir, struct dentry *dentry,
			       umode_t mode)
{
	int err = vfs_mkdir(dir, dentry, mode);
	pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
	return err;
}

static inline int ovl_do_mknod(struct inode *dir, struct dentry *dentry,
			       umode_t mode, dev_t dev)
{
	int err = vfs_mknod(dir, dentry, mode, dev);

	pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
	return err;
}

static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
				 const char *oldname)
{
	int err = vfs_symlink(dir, dentry, oldname);

	pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
	return err;
}

static inline int ovl_do_setxattr(struct dentry *dentry, const char *name,
				  const void *value, size_t size, int flags)
{
	int err = vfs_setxattr(dentry, name, value, size, flags);
	pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, 0x%x) = %i\n",
		 dentry, name, min((int)size, 48), value, size, flags, err);
	return err;
}

static inline int ovl_do_removexattr(struct dentry *dentry, const char *name)
{
	int err = vfs_removexattr(dentry, name);
	pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
	return err;
}

static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
				struct inode *newdir, struct dentry *newdentry,
				unsigned int flags)
{
	int err;

	pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
	err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
	if (err) {
		pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
			 olddentry, newdentry, err);
	}
	return err;
}

static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
{
	int err = vfs_whiteout(dir, dentry);
	pr_debug("whiteout(%pd2) = %i\n", dentry, err);
	return err;
}

static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
{
	struct dentry *ret = vfs_tmpfile(dentry, mode, 0);
	int err = PTR_ERR_OR_ZERO(ret);

	pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
	return ret;
}

static inline bool ovl_open_flags_need_copy_up(int flags)
{
	if (!flags)
		return false;

	return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
}

/* util.c */
int ovl_want_write(struct dentry *dentry);
void ovl_drop_write(struct dentry *dentry);
struct dentry *ovl_workdir(struct dentry *dentry);
const struct cred *ovl_override_creds(struct super_block *sb);
int ovl_can_decode_fh(struct super_block *sb);
struct dentry *ovl_indexdir(struct super_block *sb);
bool ovl_index_all(struct super_block *sb);
bool ovl_verify_lower(struct super_block *sb);
struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
bool ovl_dentry_remote(struct dentry *dentry);
void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
			     unsigned int mask);
bool ovl_dentry_weird(struct dentry *dentry);
enum ovl_path_type ovl_path_type(struct dentry *dentry);
void ovl_path_upper(struct dentry *dentry, struct path *path);
void ovl_path_lower(struct