/* * Cryptographic API. * * Deflate algorithm (RFC 1951), implemented here primarily for use * by IPCOMP (RFC 3173 & RFC 2394). * * Copyright (c) 2003 James Morris <jmorris@intercode.com.au> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the Free * Software Foundation; either version 2 of the License, or (at your option) * any later version. * * FIXME: deflate transforms will require up to a total of about 436k of kernel * memory on i386 (390k for compression, the rest for decompression), as the * current zlib kernel code uses a worst case pre-allocation system by default. * This needs to be fixed so that the amount of memory required is properly * related to the winbits and memlevel parameters. * * The default winbits of 11 should suit most packets, and it may be something * to configure on a per-tfm basis in the future. * * Currently, compression history is not maintained between tfm calls, as * it is not needed for IPCOMP and keeps the code simpler. It can be * implemented if someone wants it. */ #include <linux/init.h> #include <linux/module.h> #include <linux/crypto.h> #include <linux/zlib.h> #include <linux/vmalloc.h> #include <linux/interrupt.h> #include <linux/mm.h> #include <linux/net.h> #define DEFLATE_DEF_LEVEL Z_DEFAULT_COMPRESSION #define DEFLATE_DEF_WINBITS 11 #define DEFLATE_DEF_MEMLEVEL MAX_MEM_LEVEL struct deflate_ctx { struct z_stream_s comp_stream; struct z_stream_s decomp_stream; }; static int deflate_comp_init(struct deflate_ctx *ctx) { int ret = 0; struct z_stream_s *stream = &ctx->comp_stream; stream->workspace = vzalloc(zlib_deflate_workspacesize( -DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL)); if (!stream->workspace) { ret = -ENOMEM; goto out; } ret = zlib_deflateInit2(stream, DEFLATE_DEF_LEVEL, Z_DEFLATED, -DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL, Z_DEFAULT_STRATEGY); if (ret != Z_OK) { ret = -EINVAL; goto out_free; } out: return ret; out_free: vfree(stream->workspace); goto out; } static int deflate_decomp_init(struct deflate_ctx *ctx) { int ret = 0; struct z_stream_s *stream = &ctx->decomp_stream; stream->workspace = vzalloc(zlib_inflate_workspacesize()); if (!stream->workspace) { ret = -ENOMEM; goto out; } ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS); if (ret != Z_OK) { ret = -EINVAL; goto out_free; } out: return ret; out_free: vfree(stream->workspace); goto out; } static void deflate_comp_exit(struct deflate_ctx *ctx) { zlib_deflateEnd(&ctx->comp_stream); vfree(ctx->comp_stream.workspace); } static void deflate_decomp_exit(struct deflate_ctx *ctx) { zlib_inflateEnd(&ctx->decomp_stream); vfree(ctx->decomp_stream.workspace); } static int deflate_init(struct crypto_tfm *tfm) { struct deflate_ctx *ctx = crypto_tfm_ctx(tfm); int ret; ret = deflate_comp_init(ctx); if (ret) goto out; ret = deflate_decomp_init(ctx); if (ret) deflate_comp_exit(ctx); out: return ret; } static void deflate_exit(struct crypto_tfm *tfm) { struct deflate_ctx *ctx = crypto_tfm_ctx(tfm); deflate_comp_exit(ctx); deflate_decomp_exit(ctx); } static int deflate_compress(struct crypto_tfm *tfm, const u8 *src, unsigned int slen, u8 *dst, unsigned int *dlen) { int ret = 0; struct deflate_ctx *dctx = crypto_tfm_ctx(tfm); struct z_stream_s *stream = &dctx->comp_stream; ret = zlib_deflateReset(stream); if (ret != Z_OK) { ret = -EINVAL; goto out; } stream->next_in = (u8 *)src; stream->avail_in = slen; stream->next_out = (u8 *)dst; stream->avail_out = *dlen; ret = zlib_deflate(stream, Z_FINISH); if (ret != Z_STREAM_END) { ret = -EINVAL; goto out; } ret = 0; *dlen = stream->total_out; out: return ret; } static int deflate_decompress(struct crypto_tfm *tfm, const u8 *src, unsigned int slen, u8 *dst, unsigned int *dlen) { int ret = 0; struct deflate_ctx *dctx = crypto_tfm_ctx(tfm); struct z_stream_s *stream = &dctx->decomp_stream; ret = zlib_inflateReset(stream); if (ret != Z_OK) { ret = -EINVAL; goto out; } stream->next_in = (u8 *)src; stream->avail_in = slen; stream->next_out = (u8 *)dst; stream->avail_out = *dlen; ret = zlib_inflate(stream, Z_SYNC_FLUSH); /* * Work around a bug in zlib, which sometimes wants to taste an extra * byte when being used in the (undocumented) raw deflate mode. * (From USAGI). */ if (ret == Z_OK && !stream->avail_in && stream->avail_out) { u8 zerostuff = 0; stream->next_in = &zerostuff; stream->avail_in = 1; ret = zlib_inflate(stream, Z_FINISH); } if (ret != Z_STREAM_END) { ret = -EINVAL; goto out; } ret = 0; *dlen = stream->total_out; out: return ret; } static struct crypto_alg alg = { .cra_name = "deflate", .cra_flags = CRYPTO_ALG_TYPE_COMPRESS, .cra_ctxsize = sizeof(struct deflate_ctx), .cra_module = THIS_MODULE, .cra_list = LIST_HEAD_INIT(alg.cra_list), .cra_init = deflate_init, .cra_exit = deflate_exit, .cra_u = { .compress = { .coa_compress = deflate_compress, .coa_decompress = deflate_decompress } } }; static int __init deflate_mod_init(void) { return crypto_register_alg(&alg); } static void __exit deflate_mod_fini(void) { crypto_unregister_alg(&alg); } module_init(deflate_mod_init); module_exit(deflate_mod_fini); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP"); MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");