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>
36 #define DEFLATE_DEF_LEVEL Z_DEFAULT_COMPRESSION
37 #define DEFLATE_DEF_WINBITS 11
38 #define DEFLATE_DEF_MEMLEVEL MAX_MEM_LEVEL
41 struct z_stream_s comp_stream
;
42 struct z_stream_s decomp_stream
;
45 static int deflate_comp_init(struct deflate_ctx
*ctx
)
48 struct z_stream_s
*stream
= &ctx
->comp_stream
;
50 stream
->workspace
= vzalloc(zlib_deflate_workspacesize(
51 -DEFLATE_DEF_WINBITS
, DEFLATE_DEF_MEMLEVEL
));
52 if (!stream
->workspace
) {
56 ret
= zlib_deflateInit2(stream
, DEFLATE_DEF_LEVEL
, Z_DEFLATED
,
57 -DEFLATE_DEF_WINBITS
, DEFLATE_DEF_MEMLEVEL
,
66 vfree(stream
->workspace
);
70 static int deflate_decomp_init(struct deflate_ctx
*ctx
)
73 struct z_stream_s
*stream
= &ctx
->decomp_stream
;
75 stream
->workspace
= vzalloc(zlib_inflate_workspacesize());
76 if (!stream
->workspace
) {
80 ret
= zlib_inflateInit2(stream
, -DEFLATE_DEF_WINBITS
);
88 vfree(stream
->workspace
);
92 static void deflate_comp_exit(struct deflate_ctx
*ctx
)
94 zlib_deflateEnd(&ctx
->comp_stream
);
95 vfree(ctx
->comp_stream
.workspace
);
98 static void deflate_decomp_exit(struct deflate_ctx
*ctx
)
100 zlib_inflateEnd(&ctx
->decomp_stream
);
101 vfree(ctx
->decomp_stream
.workspace
);
104 static int deflate_init(struct crypto_tfm
*tfm
)
106 struct deflate_ctx
*ctx
= crypto_tfm_ctx(tfm
);
109 ret
= deflate_comp_init(ctx
);
112 ret
= deflate_decomp_init(ctx
);
114 deflate_comp_exit(ctx
);
119 static void deflate_exit(struct crypto_tfm
*tfm
)
121 struct deflate_ctx
*ctx
= crypto_tfm_ctx(tfm
);
123 deflate_comp_exit(ctx
);
124 deflate_decomp_exit(ctx
);
127 static int deflate_compress(struct crypto_tfm
*tfm
, const u8
*src
,
128 unsigned int slen
, u8
*dst
, unsigned int *dlen
)
131 struct deflate_ctx
*dctx
= crypto_tfm_ctx(tfm
);
132 struct z_stream_s
*stream
= &dctx
->comp_stream
;
134 ret
= zlib_deflateReset(stream
);
140 stream
->next_in
= (u8
*)src
;
141 stream
->avail_in
= slen
;
142 stream
->next_out
= (u8
*)dst
;
143 stream
->avail_out
= *dlen
;
145 ret
= zlib_deflate(stream
, Z_FINISH
);
146 if (ret
!= Z_STREAM_END
) {
151 *dlen
= stream
->total_out
;
156 static int deflate_decompress(struct crypto_tfm
*tfm
, const u8
*src
,
157 unsigned int slen
, u8
*dst
, unsigned int *dlen
)
161 struct deflate_ctx
*dctx
= crypto_tfm_ctx(tfm
);
162 struct z_stream_s
*stream
= &dctx
->decomp_stream
;
164 ret
= zlib_inflateReset(stream
);
170 stream
->next_in
= (u8
*)src
;
171 stream
->avail_in
= slen
;
172 stream
->next_out
= (u8
*)dst
;
173 stream
->avail_out
= *dlen
;
175 ret
= zlib_inflate(stream
, Z_SYNC_FLUSH
);
177 * Work around a bug in zlib, which sometimes wants to taste an extra
178 * byte when being used in the (undocumented) raw deflate mode.
181 if (ret
== Z_OK
&& !stream
->avail_in
&& stream
->avail_out
) {
183 stream
->next_in
= &zerostuff
;
184 stream
->avail_in
= 1;
185 ret
= zlib_inflate(stream
, Z_FINISH
);
187 if (ret
!= Z_STREAM_END
) {
192 *dlen
= stream
->total_out
;
197 static struct crypto_alg alg
= {
198 .cra_name
= "deflate",
199 .cra_flags
= CRYPTO_ALG_TYPE_COMPRESS
,
200 .cra_ctxsize
= sizeof(struct deflate_ctx
),
201 .cra_module
= THIS_MODULE
,
202 .cra_list
= LIST_HEAD_INIT(alg
.cra_list
),
203 .cra_init
= deflate_init
,
204 .cra_exit
= deflate_exit
,
205 .cra_u
= { .compress
= {
206 .coa_compress
= deflate_compress
,
207 .coa_decompress
= deflate_decompress
} }
210 static int __init
deflate_mod_init(void)
212 return crypto_register_alg(&alg
);
215 static void __exit
deflate_mod_fini(void)
217 crypto_unregister_alg(&alg
);
220 module_init(deflate_mod_init
);
221 module_exit(deflate_mod_fini
);
223 MODULE_LICENSE("GPL");
224 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
225 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
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