fs/smb/client/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
  30 typedef int (*compress_send_fn)(struct TCP_Server_Info *, int, struct smb_rqst *);
  31
  32 int 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  */
  49 bool 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  */
  64 static __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 */
  75 static inline int smb_compress(void *unused1, void *unused2, void *unused3)
  76 {
  77         return -EOPNOTSUPP;
  78 }
  79
  80 static inline bool should_compress(void *unused1, void *unused2)
  81 {
  82         return false;
  83 }
  84
  85 static 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 */