isc/win32/entropy.c

	entropy.c revision f1b68725503ff3e46001eee5a1751e29a43a09d1
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt/*
990d0e893f5b70e735cdf990af66e9ec6e91fa78Tinderbox User * Copyright (C) 2000, 2001  Internet Software Consortium.
3e02c9e33656dcd9c364633d42dd785d3e6fdd66Automatic Updater *
3e02c9e33656dcd9c364633d42dd785d3e6fdd66Automatic Updater * Permission to use, copy, modify, and distribute this software for any
c6fb85f9500350e5ce58c9a24f5d264c8a8bd6f4Automatic Updater * purpose with or without fee is hereby granted, provided that the above
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * copyright notice and this permission notice appear in all copies.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt *
3e02c9e33656dcd9c364633d42dd785d3e6fdd66Automatic Updater * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
3e02c9e33656dcd9c364633d42dd785d3e6fdd66Automatic Updater * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt */
ea94d370123a5892f6c47a97f21d1b28d44bb168Tinderbox User
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt/* $Id: entropy.c,v 1.4 2001/11/27 00:56:21 gson Exp $ */
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt/*
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * This is the system depenedent part of the ISC entropy API.
2cbb4ab75757fbb656997a82c14ca07db37d481aAutomatic Updater */
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt#include <config.h>
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
0a7ed88633a680bb881868b75ded4d09a7bbbc50Automatic Updater#include <windows.h>
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt#include <wincrypt.h>
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt#include <process.h>
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt#include <io.h>
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt#include <share.h>
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt/*
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * There is only one variable in the entropy data structures that is not
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * system independent, but pulling the structure that uses it into this file
0a7ed88633a680bb881868b75ded4d09a7bbbc50Automatic Updater * ultimately means pulling several other independent structures here also to
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * resolve their interdependencies.  Thus only the problem variable's type
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * is defined here.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt */
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt#define FILESOURCE_HANDLE_TYPE  HCRYPTPROV
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt#include "../entropy.c"
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Huntstatic unsigned int
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Huntget_from_filesource(isc_entropysource_t *source, isc_uint32_t desired) {
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    isc_entropy_t *ent = source->ent;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    unsigned char buf[128];
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    HCRYPTPROV hcryptprov = source->sources.file.handle;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    ssize_t ndesired;
6f1205897504b8f50b1785975482c995888dd630Tinderbox User    unsigned int added;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    if (source->bad)
6f1205897504b8f50b1785975482c995888dd630Tinderbox User        return (0);
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    desired = desired / 8 + (((desired & 0x07) > 0) ? 1 : 0);
fd0b768f4c23d22c89f8a156a632831583b7fb68Automatic Updater
fd0b768f4c23d22c89f8a156a632831583b7fb68Automatic Updater    added = 0;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    while (desired > 0) {
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        ndesired = ISC_MIN(desired, sizeof(buf));
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        if (!CryptGenRandom(hcryptprov, ndesired, buf)) {
6f1205897504b8f50b1785975482c995888dd630Tinderbox User            CryptReleaseContext(hcryptprov, 0);
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt            source->bad = ISC_TRUE;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt            goto out;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        }
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        entropypool_adddata(ent, buf, ndesired, ndesired * 8);
0a7ed88633a680bb881868b75ded4d09a7bbbc50Automatic Updater        added += ndesired * 8;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        desired -= ndesired;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    }
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt out:
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    return (added);
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt}
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt/*
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * Poll each source, trying to get data from it to stuff into the entropy
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt * pool.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt */
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Huntstatic void
6f1205897504b8f50b1785975482c995888dd630Tinderbox Userfillpool(isc_entropy_t *ent, unsigned int desired, isc_boolean_t blocking) {
6f1205897504b8f50b1785975482c995888dd630Tinderbox User    unsigned int added;
6f1205897504b8f50b1785975482c995888dd630Tinderbox User    unsigned int remaining;
6f1205897504b8f50b1785975482c995888dd630Tinderbox User    unsigned int needed;
8ec3c085233cedb22b05da36e2773c8f357a7e45Automatic Updater    unsigned int nsource;
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User    isc_entropysource_t *source;
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User    isc_entropysource_t *firstsource;
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User    REQUIRE(VALID_ENTROPY(ent));
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User    needed = desired;
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User    /*
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User     * This logic is a little strange, so an explanation is in order.
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User     *
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User     * If needed is 0, it means we are being asked to "fill to whatever
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User     * we think is best."  This means that if we have at least a
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User     * partially full pool (say, > 1/4th of the pool) we probably don't
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * need to add anything.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     *
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * Also, we will check to see if the "pseudo" count is too high.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * If it is, try to mix in better data.  Too high is currently
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * defined as 1/4th of the pool.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     *
12bfbed87cfffa65ac300b72c5665ab38a355c2fAutomatic Updater     * Next, if we are asked to add a specific bit of entropy, make
12bfbed87cfffa65ac300b72c5665ab38a355c2fAutomatic Updater     * certain that we will do so.  Clamp how much we try to add to
12bfbed87cfffa65ac300b72c5665ab38a355c2fAutomatic Updater     * (DIGEST_SIZE * 8 < needed < POOLBITS - entropy).
12bfbed87cfffa65ac300b72c5665ab38a355c2fAutomatic Updater     *
12bfbed87cfffa65ac300b72c5665ab38a355c2fAutomatic Updater     * Note that if we are in a blocking mode, we will only try to
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * get as much data as we need, not as much as we might want
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * to build up.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     */
6f1205897504b8f50b1785975482c995888dd630Tinderbox User    if (needed == 0) {
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        REQUIRE(!blocking);
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        if ((ent->pool.entropy >= RND_POOLBITS / 4)
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt            && (ent->pool.pseudo <= RND_POOLBITS / 4))
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt            return;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
6f1205897504b8f50b1785975482c995888dd630Tinderbox User        needed = THRESHOLD_BITS * 4;
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    } else {
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        needed = ISC_MAX(needed, THRESHOLD_BITS);
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        needed = ISC_MIN(needed, RND_POOLBITS);
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    }
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    /*
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * In any case, clamp how much we need to how much we can add.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     */
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    needed = ISC_MIN(needed, RND_POOLBITS - ent->pool.entropy);
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    /*
0a7ed88633a680bb881868b75ded4d09a7bbbc50Automatic Updater     * But wait!  If we're not yet initialized, we need at least
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     *  THRESHOLD_BITS
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * of randomness.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     */
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt    if (ent->initialized < THRESHOLD_BITS)
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt        needed = ISC_MAX(needed, THRESHOLD_BITS - ent->initialized);
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt
0a7ed88633a680bb881868b75ded4d09a7bbbc50Automatic Updater    /*
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * Poll each file source to see if we can read anything useful from
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * it.  XXXMLG When where are multiple sources, we should keep a
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * record of which one we last used so we can start from it (or the
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * next one) to avoid letting some sources build up entropy while
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     * others are always drained.
1bc5499c2a0fc5d2b11849e97cdd6305a64eb242Evan Hunt     */

    added = 0;
    remaining = needed;
    if (ent->nextsource == NULL) {
        ent->nextsource = ISC_LIST_HEAD(ent->sources);
        if (ent->nextsource == NULL)
            return;
    }
    source = ent->nextsource;
    /*
     * Remember the first source so we can break if we have looped back to
     * the beginning and still have nothing
     */
    firstsource = source;
 again_file:
    for (nsource = 0; nsource < ent->nsources; nsource++) {
        unsigned int got;

        if (remaining == 0)
            break;

        got = 0;

        if (source->type == ENTROPY_SOURCETYPE_FILE)
            got = get_from_filesource(source, remaining);

        added += got;

        remaining -= ISC_MIN(remaining, got);

        source = ISC_LIST_NEXT(source, link);
        if (source == NULL)
            source = ISC_LIST_HEAD(ent->sources);
    }
    ent->nextsource = source;

    /*
     * Go again only if there's been progress and we've not
     * gone back to the beginning
     */
    if (!(ent->nextsource == firstsource && added == 0)) {
        if (blocking && remaining != 0) {
                goto again_file;
        }
    }

    /*
     * Here, if there are bits remaining to be had and we can block,
     * check to see if we have a callback source.  If so, call them.
     */
    source = ISC_LIST_HEAD(ent->sources);
    while ((remaining != 0) && (source != NULL)) {
        unsigned int got;

        got = 0;

        if (source->type == ENTROPY_SOURCETYPE_CALLBACK)
            got = get_from_callback(source, remaining, blocking);

        added += got;
        remaining -= ISC_MIN(remaining, got);

        if (added >= needed)
            break;

        source = ISC_LIST_NEXT(source, link);
    }

    /*
     * Mark as initialized if we've added enough data.
     */
    if (ent->initialized < THRESHOLD_BITS)
        ent->initialized += added;
}


/*
 * Requires "ent" be locked.
 */
static void
destroyfilesource(isc_entropyfilesource_t *source) {
    CryptReleaseContext(source->handle, 0);
}


isc_result_t
isc_entropy_createfilesource(isc_entropy_t *ent, const char *fname) {
    isc_result_t ret;
    isc_entropysource_t *source;
    HCRYPTPROV hcryptprov;
    DWORD errval;
    BOOL err;

    REQUIRE(VALID_ENTROPY(ent));
    REQUIRE(fname != NULL);

    LOCK(&ent->lock);

    source = NULL;

    /*
     * The first time we just try to acquire the context
     */
    err = CryptAcquireContext(&hcryptprov, NULL, NULL, PROV_RSA_FULL,
                  CRYPT_VERIFYCONTEXT);
    if (!err){
        errval = GetLastError();
        ret = ISC_R_IOERROR;
        goto errout;
    }

    source = isc_mem_get(ent->mctx, sizeof(isc_entropysource_t));
    if (source == NULL) {
        ret = ISC_R_NOMEMORY;
        goto closecontext;
    }

    /*
     * From here down, no failures can occur.
     */
    source->magic = SOURCE_MAGIC;
    source->type = ENTROPY_SOURCETYPE_FILE;
    source->ent = ent;
    source->total = 0;
    source->bad = ISC_FALSE;
    memset(source->name, 0, sizeof(source->name));
    ISC_LINK_INIT(source, link);
    source->sources.file.handle = hcryptprov;

    /*
     * Hook it into the entropy system.
     */
    ISC_LIST_APPEND(ent->sources, source, link);
    ent->nsources++;

    UNLOCK(&ent->lock);
    return (ISC_R_SUCCESS);

 closecontext:
    CryptReleaseContext(hcryptprov, 0);

 errout:
    if (source != NULL)
        isc_mem_put(ent->mctx, source, sizeof(isc_entropysource_t));

    UNLOCK(&ent->lock);

    return (ret);
}