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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2024, SUSE LLC
*
* Authors: Enzo Matsumiya <ematsumiya@suse.de>
*
* This file implements I/O compression support for SMB2 messages (SMB 3.1.1 only).
* See compress/ for implementation details of each algorithm.
*
* References:
* MS-SMB2 "3.1.4.4 Compressing the Message" - for compression details
* MS-SMB2 "3.1.5.3 Decompressing the Chained Message" - for decompression details
* MS-XCA - for details of the supported algorithms
*/
#ifndef _SMB_COMPRESS_H
#define _SMB_COMPRESS_H
#include <linux/uio.h>
#include <linux/kernel.h>
#include "../common/smb2pdu.h"
#include "cifsglob.h"
/* sizeof(smb2_compression_hdr) - sizeof(OriginalPayloadSize) */
#define SMB_COMPRESS_HDR_LEN 16
/* sizeof(smb2_compression_payload_hdr) - sizeof(OriginalPayloadSize) */
#define SMB_COMPRESS_PAYLOAD_HDR_LEN 8
#define SMB_COMPRESS_MIN_LEN PAGE_SIZE
/* follows Windows implementation (as per MS-SMB2) */
#define SMB_COMPRESS_PAYLOAD_MIN_LEN 1024
#define SMB_COMPRESS_PATTERN_MIN_LEN 64
#define SMB_DECOMPRESS_MAX_LEN(_srv) \
(256 + SMB_COMPRESS_HDR_LEN + \
max_t(size_t, (_srv)->maxBuf, max_t(size_t, (_srv)->max_read, (_srv)->max_write)))
struct smb_compress_ctx {
struct TCP_Server_Info *server;
struct work_struct work;
struct mid_q_entry *mid;
void *buf; /* compressed data */
void *data; /* uncompressed data */
size_t len;
};
#ifdef CONFIG_CIFS_COMPRESSION
int smb_compress(void *buf, const void *data, size_t *len, bool chained);
int smb_decompress(const void *src, size_t src_len, void *dst, size_t *dst_len);
/**
* smb_compress_alg_valid() - Validate a compression algorithm.
* @alg: Compression algorithm to check.
* @valid_none: Conditional check whether NONE algorithm should be
* considered valid or not.
*
* If @alg is SMB3_COMPRESS_NONE, this function returns @valid_none.
*
* Note that 'NONE' (0) compressor type is considered invalid in protocol
* negotiation, as it's never requested to/returned from the server.
*
* Return: true if @alg is valid/supported, false otherwise.
*/
static __always_inline int smb_compress_alg_valid(__le16 alg, bool valid_none)
{
if (alg == SMB3_COMPRESS_NONE)
return valid_none;
if (alg == SMB3_COMPRESS_LZ77 || alg == SMB3_COMPRESS_PATTERN)
return true;
return false;
}
static __always_inline bool has_compress_hdr(void *buf)
{
struct smb2_compression_hdr *hdr = buf;
return (hdr->ProtocolId == SMB2_COMPRESSION_TRANSFORM_ID);
}
/**
* should_compress() - Determines if a request (write) or the response to a
* request (read) should be compressed.
* @tcon: tcon of the request is being sent to
* @buf: buffer with an SMB2 READ/WRITE request
*
* Return: true iff:
* - compression was successfully negotiated with server
* - server has enabled compression for the share
* - it's a read or write request
* - if write, request length is >= SMB_COMPRESS_MIN_LEN
*
* Return false otherwise.
*/
static __always_inline bool should_compress(const struct cifs_tcon *tcon, const void *buf)
{
const struct smb2_hdr *shdr = buf;
if (!tcon || !tcon->ses || !tcon->ses->server)
return false;
if (!tcon->ses->server->compression.enabled)
return false;
if (!(tcon->share_flags & SMB2_SHAREFLAG_COMPRESS_DATA))
return false;
if (shdr->Command == SMB2_WRITE) {
const struct smb2_write_req *req = buf;
return (req->Length >= SMB_COMPRESS_MIN_LEN);
}
return (shdr->Command == SMB2_READ);
}
static __always_inline size_t decompressed_size(const void *buf)
{
const struct smb2_compression_hdr *hdr = buf;
size_t size = le32_to_cpu(hdr->OriginalCompressedSegmentSize);
if (hdr->Flags == SMB2_COMPRESSION_FLAG_CHAINED)
size += le32_to_cpu(hdr->Offset);
return size;
}
#else /* CONFIG_CIFS_COMPRESSION */
#define smb_compress(arg1, arg2, arg3, arg4) (-EOPNOTSUPP)
#define smb_decompress(arg1, arg2, arg3, arg4) (-EOPNOTSUPP)
#define smb_compress_alg_valid(arg1, arg2) (-EOPNOTSUPP)
#define should_compress(arg1, arg2) (false)
#define decompress_size(arg1) (0)
#endif /* !CONFIG_CIFS_COMPRESSION */
#endif /* _SMB_COMPRESS_H */
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