zlib.c

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/*
 * Cryptographic API.
 *
 * Zlib algorithm
 *
 * Copyright 2008 Sony Corporation
 *
 * Based on deflate.c, which is
 * Copyright (c) 2003 James Morris <[email protected]>
 *
 * 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.
 */

#define pr_fmt(fmt) "%s: " fmt, __func__

#include <linux/init.h>
#include <linux/module.h>
#include <linux/zlib.h>
#include <linux/vmalloc.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/net.h>

#include <crypto/internal/compress.h>

#include <net/netlink.h>


struct zlib_ctx {
    struct z_stream_s comp_stream;
    struct z_stream_s decomp_stream;
    int decomp_windowBits;
};


static void zlib_comp_exit(struct zlib_ctx *ctx)
{
    struct z_stream_s *stream = &ctx->comp_stream;

    if (stream->workspace) {
        zlib_deflateEnd(stream);
        vfree(stream->workspace);
        stream->workspace = NULL;
    }
}

static void zlib_decomp_exit(struct zlib_ctx *ctx)
{
    struct z_stream_s *stream = &ctx->decomp_stream;

    if (stream->workspace) {
        zlib_inflateEnd(stream);
        vfree(stream->workspace);
        stream->workspace = NULL;
    }
}

static int zlib_init(struct crypto_tfm *tfm)
{
    return 0;
}

static void zlib_exit(struct crypto_tfm *tfm)
{
    struct zlib_ctx *ctx = crypto_tfm_ctx(tfm);

    zlib_comp_exit(ctx);
    zlib_decomp_exit(ctx);
}


static int zlib_compress_setup(struct crypto_pcomp *tfm, void *params,
                   unsigned int len)
{
    struct zlib_ctx *ctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
    struct z_stream_s *stream = &ctx->comp_stream;
    struct nlattr *tb[ZLIB_COMP_MAX + 1];
    int window_bits, mem_level;
    size_t workspacesize;
    int ret;

    ret = nla_parse(tb, ZLIB_COMP_MAX, params, len, NULL);
    if (ret)
        return ret;

    zlib_comp_exit(ctx);

    window_bits = tb[ZLIB_COMP_WINDOWBITS]
                    ? nla_get_u32(tb[ZLIB_COMP_WINDOWBITS])
                    : MAX_WBITS;
    mem_level = tb[ZLIB_COMP_MEMLEVEL]
                    ? nla_get_u32(tb[ZLIB_COMP_MEMLEVEL])
                    : DEF_MEM_LEVEL;

    workspacesize = zlib_deflate_workspacesize(window_bits, mem_level);
    stream->workspace = vzalloc(workspacesize);
    if (!stream->workspace)
        return -ENOMEM;

    ret = zlib_deflateInit2(stream,
                tb[ZLIB_COMP_LEVEL]
                    ? nla_get_u32(tb[ZLIB_COMP_LEVEL])
                    : Z_DEFAULT_COMPRESSION,
                tb[ZLIB_COMP_METHOD]
                    ? nla_get_u32(tb[ZLIB_COMP_METHOD])
                    : Z_DEFLATED,
                window_bits,
                mem_level,
                tb[ZLIB_COMP_STRATEGY]
                    ? nla_get_u32(tb[ZLIB_COMP_STRATEGY])
                    : Z_DEFAULT_STRATEGY);
    if (ret != Z_OK) {
        vfree(stream->workspace);
        stream->workspace = NULL;
        return -EINVAL;
    }

    return 0;
}

static int zlib_compress_init(struct crypto_pcomp *tfm)
{
    int ret;
    struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
    struct z_stream_s *stream = &dctx->comp_stream;

    ret = zlib_deflateReset(stream);
    if (ret != Z_OK)
        return -EINVAL;

    return 0;
}

static int zlib_compress_update(struct crypto_pcomp *tfm,
                struct comp_request *req)
{
    int ret;
    struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
    struct z_stream_s *stream = &dctx->comp_stream;

    pr_debug("avail_in %u, avail_out %u\n", req->avail_in, req->avail_out);
    stream->next_in = req->next_in;
    stream->avail_in = req->avail_in;
    stream->next_out = req->next_out;
    stream->avail_out = req->avail_out;

    ret = zlib_deflate(stream, Z_NO_FLUSH);
    switch (ret) {
    case Z_OK:
        break;

    case Z_BUF_ERROR:
        pr_debug("zlib_deflate could not make progress\n");
        return -EAGAIN;

    default:
        pr_debug("zlib_deflate failed %d\n", ret);
        return -EINVAL;
    }

    ret = req->avail_out - stream->avail_out;
    pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)\n",
         stream->avail_in, stream->avail_out,
         req->avail_in - stream->avail_in, ret);
    req->next_in = stream->next_in;
    req->avail_in = stream->avail_in;
    req->next_out = stream->next_out;
    req->avail_out = stream->avail_out;
    return ret;
}

static int zlib_compress_final(struct crypto_pcomp *tfm,
                   struct comp_request *req)
{
    int ret;
    struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
    struct z_stream_s *stream = &dctx->comp_stream;

    pr_debug("avail_in %u, avail_out %u\n", req->avail_in, req->avail_out);
    stream->next_in = req->next_in;
    stream->avail_in = req->avail_in;
    stream->next_out = req->next_out;
    stream->avail_out = req->avail_out;

    ret = zlib_deflate(stream, Z_FINISH);
    if (ret != Z_STREAM_END) {
        pr_debug("zlib_deflate failed %d\n", ret);
        return -EINVAL;
    }

    ret = req->avail_out - stream->avail_out;
    pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)\n",
         stream->avail_in, stream->avail_out,
         req->avail_in - stream->avail_in, ret);
    req->next_in = stream->next_in;
    req->avail_in = stream->avail_in;
    req->next_out = stream->next_out;
    req->avail_out = stream->avail_out;
    return ret;
}


static int zlib_decompress_setup(struct crypto_pcomp *tfm, void *params,
                 unsigned int len)
{
    struct zlib_ctx *ctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
    struct z_stream_s *stream = &ctx->decomp_stream;
    struct nlattr *tb[ZLIB_DECOMP_MAX + 1];
    int ret = 0;

    ret = nla_parse(tb, ZLIB_DECOMP_MAX, params, len, NULL);
    if (ret)
        return ret;

    zlib_decomp_exit(ctx);

    ctx->decomp_windowBits = tb[ZLIB_DECOMP_WINDOWBITS]
                 ? nla_get_u32(tb[ZLIB_DECOMP_WINDOWBITS])
                 : DEF_WBITS;

    stream->workspace = vzalloc(zlib_inflate_workspacesize());
    if (!stream->workspace)
        return -ENOMEM;

    ret = zlib_inflateInit2(stream, ctx->decomp_windowBits);
    if (ret != Z_OK) {
        vfree(stream->workspace);
        stream->workspace = NULL;
        return -EINVAL;
    }

    return 0;
}

static int zlib_decompress_init(struct crypto_pcomp *tfm)
{
    int ret;
    struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
    struct z_stream_s *stream = &dctx->decomp_stream;

    ret = zlib_inflateReset(stream);
    if (ret != Z_OK)
        return -EINVAL;

    return 0;
}

static int zlib_decompress_update(struct crypto_pcomp *tfm,
                  struct comp_request *req)
{
    int ret;
    struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
    struct z_stream_s *stream = &dctx->decomp_stream;

    pr_debug("avail_in %u, avail_out %u\n", req->avail_in, req->avail_out);
    stream->next_in = req->next_in;
    stream->avail_in = req->avail_in;
    stream->next_out = req->next_out;
    stream->avail_out = req->avail_out;

    ret = zlib_inflate(stream, Z_SYNC_FLUSH);
    switch (ret) {
    case Z_OK:
    case Z_STREAM_END:
        break;

    case Z_BUF_ERROR:
        pr_debug("zlib_inflate could not make progress\n");
        return -EAGAIN;

    default:
        pr_debug("zlib_inflate failed %d\n", ret);
        return -EINVAL;
    }

    ret = req->avail_out - stream->avail_out;
    pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)\n",
         stream->avail_in, stream->avail_out,
         req->avail_in - stream->avail_in, ret);
    req->next_in = stream->next_in;
    req->avail_in = stream->avail_in;
    req->next_out = stream->next_out;
    req->avail_out = stream->avail_out;
    return ret;
}

static int zlib_decompress_final(struct crypto_pcomp *tfm,
                 struct comp_request *req)
{
    int ret;
    struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
    struct z_stream_s *stream = &dctx->decomp_stream;

    pr_debug("avail_in %u, avail_out %u\n", req->avail_in, req->avail_out);
    stream->next_in = req->next_in;
    stream->avail_in = req->avail_in;
    stream->next_out = req->next_out;
    stream->avail_out = req->avail_out;

    if (dctx->decomp_windowBits < 0) {
        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) {
            const void *saved_next_in = stream->next_in;
            u8 zerostuff = 0;

            stream->next_in = &zerostuff;
            stream->avail_in = 1;
            ret = zlib_inflate(stream, Z_FINISH);
            stream->next_in = saved_next_in;
            stream->avail_in = 0;
        }
    } else
        ret = zlib_inflate(stream, Z_FINISH);
    if (ret != Z_STREAM_END) {
        pr_debug("zlib_inflate failed %d\n", ret);
        return -EINVAL;
    }

    ret = req->avail_out - stream->avail_out;
    pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)\n",
         stream->avail_in, stream->avail_out,
         req->avail_in - stream->avail_in, ret);
    req->next_in = stream->next_in;
    req->avail_in = stream->avail_in;
    req->next_out = stream->next_out;
    req->avail_out = stream->avail_out;
    return ret;
}


static struct pcomp_alg zlib_alg = {
    .compress_setup     = zlib_compress_setup,
    .compress_init      = zlib_compress_init,
    .compress_update    = zlib_compress_update,
    .compress_final     = zlib_compress_final,
    .decompress_setup   = zlib_decompress_setup,
    .decompress_init    = zlib_decompress_init,
    .decompress_update  = zlib_decompress_update,
    .decompress_final   = zlib_decompress_final,

    .base           = {
        .cra_name   = "zlib",
        .cra_flags  = CRYPTO_ALG_TYPE_PCOMPRESS,
        .cra_ctxsize    = sizeof(struct zlib_ctx),
        .cra_module = THIS_MODULE,
        .cra_init   = zlib_init,
        .cra_exit   = zlib_exit,
    }
};

static int __init zlib_mod_init(void)
{
    return crypto_register_pcomp(&zlib_alg);
}

static void __exit zlib_mod_fini(void)
{
    crypto_unregister_pcomp(&zlib_alg);
}

module_init(zlib_mod_init);
module_exit(zlib_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Zlib Compression Algorithm");
MODULE_AUTHOR("Sony Corporation");