1/* SPDX-License-Identifier: GPL-2.0-only */
 2/*
 3 * Copyright (C) 2024, SUSE LLC
 4 *
 5 * Authors: Enzo Matsumiya <ematsumiya@suse.de>
 6 *
 7 * This file implements I/O compression support for SMB2 messages (SMB 3.1.1 only).
 8 * See compress/ for implementation details of each algorithm.
 9 *
10 * References:
11 * MS-SMB2 "3.1.4.4 Compressing the Message" - for compression details
12 * MS-SMB2 "3.1.5.3 Decompressing the Chained Message" - for decompression details
13 * MS-XCA - for details of the supported algorithms
14 */
15#ifndef _SMB_COMPRESS_H
16#define _SMB_COMPRESS_H
17
18#include <linux/uio.h>
19#include <linux/kernel.h>
20#include "../common/smb2pdu.h"
21#include "cifsglob.h"
22
23/* sizeof(smb2_compression_hdr) - sizeof(OriginalPayloadSize) */
24#define SMB_COMPRESS_HDR_LEN		16
25/* sizeof(smb2_compression_payload_hdr) - sizeof(OriginalPayloadSize) */
26#define SMB_COMPRESS_PAYLOAD_HDR_LEN	8
27#define SMB_COMPRESS_MIN_LEN		PAGE_SIZE
28
29#ifdef CONFIG_CIFS_COMPRESSION
30typedef int (*compress_send_fn)(struct TCP_Server_Info *, int, struct smb_rqst *);
31
32int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq, compress_send_fn send_fn);
33
34/**
35 * should_compress() - Determines if a request (write) or the response to a
36 *		       request (read) should be compressed.
37 * @tcon: tcon of the request is being sent to
38 * @rqst: request to evaluate
39 *
40 * Return: true iff:
41 * - compression was successfully negotiated with server
42 * - server has enabled compression for the share
43 * - it's a read or write request
44 * - (write only) request length is >= SMB_COMPRESS_MIN_LEN
45 * - (write only) is_compressible() returns 1
46 *
47 * Return false otherwise.
48 */
49bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq);
50
51/**
52 * smb_compress_alg_valid() - Validate a compression algorithm.
53 * @alg: Compression algorithm to check.
54 * @valid_none: Conditional check whether NONE algorithm should be
55 *		considered valid or not.
56 *
57 * If @alg is SMB3_COMPRESS_NONE, this function returns @valid_none.
58 *
59 * Note that 'NONE' (0) compressor type is considered invalid in protocol
60 * negotiation, as it's never requested to/returned from the server.
61 *
62 * Return: true if @alg is valid/supported, false otherwise.
63 */
64static __always_inline int smb_compress_alg_valid(__le16 alg, bool valid_none)
65{
66	if (alg == SMB3_COMPRESS_NONE)
67		return valid_none;
68
69	if (alg == SMB3_COMPRESS_LZ77 || alg == SMB3_COMPRESS_PATTERN)
70		return true;
71
72	return false;
73}
74#else /* !CONFIG_CIFS_COMPRESSION */
75static inline int smb_compress(void *unused1, void *unused2, void *unused3)
76{
77	return -EOPNOTSUPP;
78}
79
80static inline bool should_compress(void *unused1, void *unused2)
81{
82	return false;
83}
84
85static inline int smb_compress_alg_valid(__le16 unused1, bool unused2)
86{
87	return -EOPNOTSUPP;
88}
89#endif /* !CONFIG_CIFS_COMPRESSION */
90#endif /* _SMB_COMPRESS_H */