fs/smb/client/reparse.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (c) 2024 Paulo Alcantara <pc@manguebit.com>
 */

#ifndef _CIFS_REPARSE_H
#define _CIFS_REPARSE_H

#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/uidgid.h>
#include "fs_context.h"
#include "cifsglob.h"

#define REPARSE_SYM_PATH_MAX 4060

/*
 * Used only by cifs.ko to ignore reparse points from files when client or
 * server doesn't support FSCTL_GET_REPARSE_POINT.
 */
#define IO_REPARSE_TAG_INTERNAL ((__u32)~0U)

static inline dev_t reparse_mkdev(void *ptr)
{
	u64 v = le64_to_cpu(*(__le64 *)ptr);

	return MKDEV(v & 0xffffffff, v >> 32);
}

static inline kuid_t wsl_make_kuid(struct cifs_sb_info *cifs_sb,
				   void *ptr)
{
	u32 uid = le32_to_cpu(*(__le32 *)ptr);

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_OVERR_UID)
		return cifs_sb->ctx->linux_uid;
	return make_kuid(current_user_ns(), uid);
}

static inline kgid_t wsl_make_kgid(struct cifs_sb_info *cifs_sb,
				   void *ptr)
{
	u32 gid = le32_to_cpu(*(__le32 *)ptr);

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_OVERR_GID)
		return cifs_sb->ctx->linux_gid;
	return make_kgid(current_user_ns(), gid);
}

static inline u64 reparse_mode_nfs_type(mode_t mode)
{
	switch (mode & S_IFMT) {
	case S_IFLNK: return NFS_SPECFILE_LNK;
	case S_IFBLK: return NFS_SPECFILE_BLK;
	case S_IFCHR: return NFS_SPECFILE_CHR;
	case S_IFIFO: return NFS_SPECFILE_FIFO;
	case S_IFSOCK: return NFS_SPECFILE_SOCK;
	}
	return 0;
}

static inline u32 reparse_mode_wsl_tag(mode_t mode)
{
	switch (mode & S_IFMT) {
	case S_IFLNK: return IO_REPARSE_TAG_LX_SYMLINK;
	case S_IFBLK: return IO_REPARSE_TAG_LX_BLK;
	case S_IFCHR: return IO_REPARSE_TAG_LX_CHR;
	case S_IFIFO: return IO_REPARSE_TAG_LX_FIFO;
	case S_IFSOCK: return IO_REPARSE_TAG_AF_UNIX;
	}
	return 0;
}

/*
 * Match a reparse point inode if reparse tag and ctime haven't changed.
 *
 * Windows Server updates ctime of reparse points when their data have changed.
 * The server doesn't allow changing reparse tags from existing reparse points,
 * though it's worth checking.
 */
static inline bool reparse_inode_match(struct inode *inode,
				       struct cifs_fattr *fattr)
{
	struct cifsInodeInfo *cinode = CIFS_I(inode);
	struct timespec64 ctime = inode_get_ctime(inode);

	/*
	 * Do not match reparse tags when client or server doesn't support
	 * FSCTL_GET_REPARSE_POINT.  @fattr->cf_cifstag should contain correct
	 * reparse tag from query dir response but the client won't be able to
	 * read the reparse point data anyway.  This spares us a revalidation.
	 */
	if (cinode->reparse_tag != IO_REPARSE_TAG_INTERNAL &&
	    cinode->reparse_tag != fattr->cf_cifstag)
		return false;
	return (cinode->cifsAttrs & ATTR_REPARSE) &&
		timespec64_equal(&ctime, &fattr->cf_ctime);
}

static inline bool cifs_open_data_reparse(struct cifs_open_info_data *data)
{
	u32 attrs;
	bool ret;

	if (data->contains_posix_file_info) {
		struct smb311_posix_qinfo *fi = &data->posix_fi;

		attrs = le32_to_cpu(fi->DosAttributes);
		if (data->reparse_point) {
			attrs |= ATTR_REPARSE;
			fi->DosAttributes = cpu_to_le32(attrs);
		}

	} else {
		struct smb2_file_all_info *fi = &data->fi;

		attrs = le32_to_cpu(fi->Attributes);
		if (data->reparse_point) {
			attrs |= ATTR_REPARSE;
			fi->Attributes = cpu_to_le32(attrs);
		}
	}

	ret = attrs & ATTR_REPARSE;

	return ret;
}

bool cifs_reparse_point_to_fattr(struct cifs_sb_info *cifs_sb,
				 struct cifs_fattr *fattr,
				 struct cifs_open_info_data *data);
int create_reparse_symlink(const unsigned int xid, struct inode *inode,
				struct dentry *dentry, struct cifs_tcon *tcon,
				const char *full_path, const char *symname);
int mknod_reparse(unsigned int xid, struct inode *inode,
		       struct dentry *dentry, struct cifs_tcon *tcon,
		       const char *full_path, umode_t mode, dev_t dev);
struct reparse_data_buffer *smb2_get_reparse_point_buffer(const struct kvec *rsp_iov, u32 *len);

#endif /* _CIFS_REPARSE_H */