compress.h

 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
32
33int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq, compress_send_fn send_fn);
34bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq);
35
36/*
37 * smb_compress_alg_valid() - Validate a compression algorithm.
38 * @alg: Compression algorithm to check.
39 * @valid_none: Conditional check whether NONE algorithm should be
40 *		considered valid or not.
41 *
42 * If @alg is SMB3_COMPRESS_NONE, this function returns @valid_none.
43 *
44 * Note that 'NONE' (0) compressor type is considered invalid in protocol
45 * negotiation, as it's never requested to/returned from the server.
46 *
47 * Return: true if @alg is valid/supported, false otherwise.
48 */
49static __always_inline int smb_compress_alg_valid(__le16 alg, bool valid_none)
50{
51	if (alg == SMB3_COMPRESS_NONE)
52		return valid_none;
53
54	if (alg == SMB3_COMPRESS_LZ77 || alg == SMB3_COMPRESS_PATTERN)
55		return true;
56
57	return false;
58}
59#else /* !CONFIG_CIFS_COMPRESSION */
60static inline int smb_compress(void *unused1, void *unused2, void *unused3)
61{
62	return -EOPNOTSUPP;
63}
64
65static inline bool should_compress(void *unused1, void *unused2)
66{
67	return false;
68}
69
70static inline int smb_compress_alg_valid(__le16 unused1, bool unused2)
71{
72	return -EOPNOTSUPP;
73}
74#endif /* !CONFIG_CIFS_COMPRESSION */
75#endif /* _SMB_COMPRESS_H */