/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *   Copyright (C) 2021 Samsung Electronics Co., Ltd.
 */

#ifndef __XATTR_H__
#define __XATTR_H__

/*
 * These are on-disk structures to store additional metadata into xattr to
 * reproduce windows filesystem semantics. And they are encoded with NDR to
 * compatible with samba's xattr meta format. The compatibility with samba
 * is important because it can lose the information(file attribute,
 * creation time, acls) about the existing files when switching between
 * ksmbd and samba.
 */

/*
 * Dos attribute flags used for what variable is valid.
 */
enum {
        XATTR_DOSINFO_ATTRIB            = 0x00000001,
        XATTR_DOSINFO_EA_SIZE           = 0x00000002,
        XATTR_DOSINFO_SIZE              = 0x00000004,
        XATTR_DOSINFO_ALLOC_SIZE        = 0x00000008,
        XATTR_DOSINFO_CREATE_TIME       = 0x00000010,
        XATTR_DOSINFO_CHANGE_TIME       = 0x00000020,
        XATTR_DOSINFO_ITIME             = 0x00000040
};

/*
 * Dos attribute structure which is compatible with samba's one.
 * Storing it into the xattr named "DOSATTRIB" separately from inode
 * allows ksmbd to faithfully reproduce windows filesystem semantics
 * on top of a POSIX filesystem.
 */
struct xattr_dos_attrib {
        __u16   version;        /* version 3 or version 4 */
        __u32   flags;          /* valid flags */
        __u32   attr;           /* Dos attribute */
        __u32   ea_size;        /* EA size */
        __u64   size;
        __u64   alloc_size;
        __u64   create_time;    /* File creation time */
        __u64   change_time;    /* File change time */
        __u64   itime;          /* Invented/Initial time */
};

/*
 * Enumeration is used for computing posix acl hash.
 */
enum {
        SMB_ACL_TAG_INVALID = 0,
        SMB_ACL_USER,
        SMB_ACL_USER_OBJ,
        SMB_ACL_GROUP,
        SMB_ACL_GROUP_OBJ,
        SMB_ACL_OTHER,
        SMB_ACL_MASK
};

#define SMB_ACL_READ                    4
#define SMB_ACL_WRITE                   2
#define SMB_ACL_EXECUTE                 1

struct xattr_acl_entry {
        int type;
        uid_t uid;
        gid_t gid;
        mode_t perm;
};

/*
 * xattr_smb_acl structure is used for computing posix acl hash.
 */
struct xattr_smb_acl {
        int count;
        int next;
        struct xattr_acl_entry entries[] __counted_by(count);
};

/* 64bytes hash in xattr_ntacl is computed with sha256 */
#define XATTR_SD_HASH_TYPE_SHA256       0x1
#define XATTR_SD_HASH_SIZE              64

/*
 * xattr_ntacl is used for storing ntacl and hashes.
 * Hash is used for checking valid posix acl and ntacl in xattr.
 */
struct xattr_ntacl {
        __u16   version; /* version 4*/
        void    *sd_buf;
        __u32   sd_size;
        __u16   hash_type; /* hash type */
        __u8    desc[10]; /* posix_acl description */
        __u16   desc_len;
        __u64   current_time;
        __u8    hash[XATTR_SD_HASH_SIZE]; /* 64bytes hash for ntacl */
        __u8    posix_acl_hash[XATTR_SD_HASH_SIZE]; /* 64bytes hash for posix acl */
};

/* DOS ATTRIBUTE XATTR PREFIX */
#define DOS_ATTRIBUTE_PREFIX            "DOSATTRIB"
#define DOS_ATTRIBUTE_PREFIX_LEN        (sizeof(DOS_ATTRIBUTE_PREFIX) - 1)
#define XATTR_NAME_DOS_ATTRIBUTE        (XATTR_USER_PREFIX DOS_ATTRIBUTE_PREFIX)
#define XATTR_NAME_DOS_ATTRIBUTE_LEN    \
                (sizeof(XATTR_USER_PREFIX DOS_ATTRIBUTE_PREFIX) - 1)

/* STREAM XATTR PREFIX */
#define STREAM_PREFIX                   "DosStream."
#define STREAM_PREFIX_LEN               (sizeof(STREAM_PREFIX) - 1)
#define XATTR_NAME_STREAM               (XATTR_USER_PREFIX STREAM_PREFIX)
#define XATTR_NAME_STREAM_LEN           (sizeof(XATTR_NAME_STREAM) - 1)

/* SECURITY DESCRIPTOR(NTACL) XATTR PREFIX */
#define SD_PREFIX                       "NTACL"
#define SD_PREFIX_LEN   (sizeof(SD_PREFIX) - 1)
#define XATTR_NAME_SD   (XATTR_SECURITY_PREFIX SD_PREFIX)
#define XATTR_NAME_SD_LEN       \
                (sizeof(XATTR_SECURITY_PREFIX SD_PREFIX) - 1)

#endif /* __XATTR_H__ */