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
43 int decomp_initialized
;
44 struct z_stream_s comp_stream
;
45 struct z_stream_s decomp_stream
;
48 static inline int deflate_gfp(void)
50 return in_softirq() ? GFP_ATOMIC
: GFP_KERNEL
;
53 static int deflate_init(void *ctx
)
58 static void deflate_exit(void *ctx
)
60 struct deflate_ctx
*dctx
= ctx
;
62 if (dctx
->comp_initialized
)
63 vfree(dctx
->comp_stream
.workspace
);
64 if (dctx
->decomp_initialized
)
65 kfree(dctx
->decomp_stream
.workspace
);
69 * Lazy initialization to make interface simple without allocating
70 * un-needed workspaces. Thus can be called in softirq context.
72 static int deflate_comp_init(struct deflate_ctx
*ctx
)
75 struct z_stream_s
*stream
= &ctx
->comp_stream
;
77 stream
->workspace
= __vmalloc(zlib_deflate_workspacesize(),
78 deflate_gfp()|__GFP_HIGHMEM
,
80 if (!stream
->workspace
) {
84 memset(stream
->workspace
, 0, zlib_deflate_workspacesize());
85 ret
= zlib_deflateInit2(stream
, DEFLATE_DEF_LEVEL
, Z_DEFLATED
,
86 -DEFLATE_DEF_WINBITS
, DEFLATE_DEF_MEMLEVEL
,
92 ctx
->comp_initialized
= 1;
96 vfree(stream
->workspace
);
100 static int deflate_decomp_init(struct deflate_ctx
*ctx
)
103 struct z_stream_s
*stream
= &ctx
->decomp_stream
;
105 stream
->workspace
= kmalloc(zlib_inflate_workspacesize(),
107 if (!stream
->workspace
) {
111 memset(stream
->workspace
, 0, zlib_inflate_workspacesize());
112 ret
= zlib_inflateInit2(stream
, -DEFLATE_DEF_WINBITS
);
117 ctx
->decomp_initialized
= 1;
121 kfree(stream
->workspace
);
125 static int deflate_compress(void *ctx
, const u8
*src
, unsigned int slen
,
126 u8
*dst
, unsigned int *dlen
)
129 struct deflate_ctx
*dctx
= ctx
;
130 struct z_stream_s
*stream
= &dctx
->comp_stream
;
132 if (!dctx
->comp_initialized
) {
133 ret
= deflate_comp_init(dctx
);
138 ret
= zlib_deflateReset(stream
);
144 stream
->next_in
= (u8
*)src
;
145 stream
->avail_in
= slen
;
146 stream
->next_out
= (u8
*)dst
;
147 stream
->avail_out
= *dlen
;
149 ret
= zlib_deflate(stream
, Z_FINISH
);
150 if (ret
!= Z_STREAM_END
) {
155 *dlen
= stream
->total_out
;
160 static int deflate_decompress(void *ctx
, const u8
*src
, unsigned int slen
,
161 u8
*dst
, unsigned int *dlen
)
165 struct deflate_ctx
*dctx
= ctx
;
166 struct z_stream_s
*stream
= &dctx
->decomp_stream
;
168 if (!dctx
->decomp_initialized
) {
169 ret
= deflate_decomp_init(dctx
);
174 ret
= zlib_inflateReset(stream
);
180 stream
->next_in
= (u8
*)src
;
181 stream
->avail_in
= slen
;
182 stream
->next_out
= (u8
*)dst
;
183 stream
->avail_out
= *dlen
;
185 ret
= zlib_inflate(stream
, Z_SYNC_FLUSH
);
187 * Work around a bug in zlib, which sometimes wants to taste an extra
188 * byte when being used in the (undocumented) raw deflate mode.
191 if (ret
== Z_OK
&& !stream
->avail_in
&& stream
->avail_out
) {
193 stream
->next_in
= &zerostuff
;
194 stream
->avail_in
= 1;
195 ret
= zlib_inflate(stream
, Z_FINISH
);
197 if (ret
!= Z_STREAM_END
) {
202 *dlen
= stream
->total_out
;
207 static struct crypto_alg alg
= {
208 .cra_name
= "deflate",
209 .cra_flags
= CRYPTO_ALG_TYPE_COMPRESS
,
210 .cra_ctxsize
= sizeof(struct deflate_ctx
),
211 .cra_module
= THIS_MODULE
,
212 .cra_list
= LIST_HEAD_INIT(alg
.cra_list
),
213 .cra_u
= { .compress
= {
214 .coa_init
= deflate_init
,
215 .coa_exit
= deflate_exit
,
216 .coa_compress
= deflate_compress
,
217 .coa_decompress
= deflate_decompress
} }
220 static int __init
init(void)
222 return crypto_register_alg(&alg
);
225 static void __exit
fini(void)
227 crypto_unregister_alg(&alg
);
233 MODULE_LICENSE("GPL");
234 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
235 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");