4 * Deflate algorithm (RFC 1951), implemented here primarily for use
5 * by IPCOMP (RFC 3173 & RFC 2394).
7 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the Free
11 * Software Foundation; either version 2 of the License, or (at your option)
14 * FIXME: deflate transforms will require up to a total of about 436k of kernel
15 * memory on i386 (390k for compression, the rest for decompression), as the
16 * current zlib kernel code uses a worst case pre-allocation system by default.
17 * This needs to be fixed so that the amount of memory required is properly
18 * related to the winbits and memlevel parameters.
20 * The default winbits of 11 should suit most packets, and it may be something
21 * to configure on a per-tfm basis in the future.
23 * Currently, compression history is not maintained between tfm calls, as
24 * it is not needed for IPCOMP and keeps the code simpler. It can be
25 * implemented if someone wants it.
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/crypto.h>
30 #include <linux/zlib.h>
31 #include <linux/vmalloc.h>
32 #include <linux/interrupt.h>
34 #include <linux/net.h>
35 #include <linux/slab.h>
37 #define DEFLATE_DEF_LEVEL Z_DEFAULT_COMPRESSION
38 #define DEFLATE_DEF_WINBITS 11
39 #define DEFLATE_DEF_MEMLEVEL MAX_MEM_LEVEL
42 struct z_stream_s comp_stream
;
43 struct z_stream_s decomp_stream
;
46 static int deflate_comp_init(struct deflate_ctx
*ctx
)
49 struct z_stream_s
*stream
= &ctx
->comp_stream
;
51 stream
->workspace
= vmalloc(zlib_deflate_workspacesize());
52 if (!stream
->workspace
) {
56 memset(stream
->workspace
, 0, zlib_deflate_workspacesize());
57 ret
= zlib_deflateInit2(stream
, DEFLATE_DEF_LEVEL
, Z_DEFLATED
,
58 -DEFLATE_DEF_WINBITS
, DEFLATE_DEF_MEMLEVEL
,
67 vfree(stream
->workspace
);
71 static int deflate_decomp_init(struct deflate_ctx
*ctx
)
74 struct z_stream_s
*stream
= &ctx
->decomp_stream
;
76 stream
->workspace
= kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL
);
77 if (!stream
->workspace
) {
81 memset(stream
->workspace
, 0, zlib_inflate_workspacesize());
82 ret
= zlib_inflateInit2(stream
, -DEFLATE_DEF_WINBITS
);
90 kfree(stream
->workspace
);
94 static void deflate_comp_exit(struct deflate_ctx
*ctx
)
96 zlib_deflateEnd(&ctx
->comp_stream
);
97 vfree(ctx
->comp_stream
.workspace
);
100 static void deflate_decomp_exit(struct deflate_ctx
*ctx
)
102 zlib_inflateEnd(&ctx
->decomp_stream
);
103 kfree(ctx
->decomp_stream
.workspace
);
106 static int deflate_init(void *ctx
)
110 ret
= deflate_comp_init(ctx
);
113 ret
= deflate_decomp_init(ctx
);
115 deflate_comp_exit(ctx
);
120 static void deflate_exit(void *ctx
)
122 deflate_comp_exit(ctx
);
123 deflate_decomp_exit(ctx
);
126 static int deflate_compress(void *ctx
, const u8
*src
, unsigned int slen
,
127 u8
*dst
, unsigned int *dlen
)
130 struct deflate_ctx
*dctx
= ctx
;
131 struct z_stream_s
*stream
= &dctx
->comp_stream
;
133 ret
= zlib_deflateReset(stream
);
139 stream
->next_in
= (u8
*)src
;
140 stream
->avail_in
= slen
;
141 stream
->next_out
= (u8
*)dst
;
142 stream
->avail_out
= *dlen
;
144 ret
= zlib_deflate(stream
, Z_FINISH
);
145 if (ret
!= Z_STREAM_END
) {
150 *dlen
= stream
->total_out
;
155 static int deflate_decompress(void *ctx
, const u8
*src
, unsigned int slen
,
156 u8
*dst
, unsigned int *dlen
)
160 struct deflate_ctx
*dctx
= ctx
;
161 struct z_stream_s
*stream
= &dctx
->decomp_stream
;
163 ret
= zlib_inflateReset(stream
);
169 stream
->next_in
= (u8
*)src
;
170 stream
->avail_in
= slen
;
171 stream
->next_out
= (u8
*)dst
;
172 stream
->avail_out
= *dlen
;
174 ret
= zlib_inflate(stream
, Z_SYNC_FLUSH
);
176 * Work around a bug in zlib, which sometimes wants to taste an extra
177 * byte when being used in the (undocumented) raw deflate mode.
180 if (ret
== Z_OK
&& !stream
->avail_in
&& stream
->avail_out
) {
182 stream
->next_in
= &zerostuff
;
183 stream
->avail_in
= 1;
184 ret
= zlib_inflate(stream
, Z_FINISH
);
186 if (ret
!= Z_STREAM_END
) {
191 *dlen
= stream
->total_out
;
196 static struct crypto_alg alg
= {
197 .cra_name
= "deflate",
198 .cra_flags
= CRYPTO_ALG_TYPE_COMPRESS
,
199 .cra_ctxsize
= sizeof(struct deflate_ctx
),
200 .cra_module
= THIS_MODULE
,
201 .cra_list
= LIST_HEAD_INIT(alg
.cra_list
),
202 .cra_u
= { .compress
= {
203 .coa_init
= deflate_init
,
204 .coa_exit
= deflate_exit
,
205 .coa_compress
= deflate_compress
,
206 .coa_decompress
= deflate_decompress
} }
209 static int __init
init(void)
211 return crypto_register_alg(&alg
);
214 static void __exit
fini(void)
216 crypto_unregister_alg(&alg
);
222 MODULE_LICENSE("GPL");
223 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
224 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");