lib/pk11wrap/pk11cxt.c

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
 * This file PK11Contexts which are  used in multipart hashing,
 * encryption/decryption, and signing/verication operations.
 */

#include "seccomon.h"
#include "secmod.h"
#include "nssilock.h"
#include "secmodi.h"
#include "secmodti.h"
#include "pkcs11.h"
#include "pk11func.h"
#include "secitem.h"
#include "secoid.h"
#include "sechash.h"
#include "secerr.h"

static const SECItem pk11_null_params = { 0 };

/**********************************************************************
 *
 *                   Now Deal with Crypto Contexts
 *
 **********************************************************************/

/*
 * the monitors...
 */
void
PK11_EnterContextMonitor(PK11Context *cx)
{
    /* if we own the session and our slot is ThreadSafe, only monitor
     * the Context */
    if ((cx->ownSession) && (cx->slot->isThreadSafe)) {
        /* Should this use monitors instead? */
        PZ_Lock(cx->sessionLock);
    } else {
        PK11_EnterSlotMonitor(cx->slot);
    }
}

void
PK11_ExitContextMonitor(PK11Context *cx)
{
    /* if we own the session and our slot is ThreadSafe, only monitor
     * the Context */
    if ((cx->ownSession) && (cx->slot->isThreadSafe)) {
        /* Should this use monitors instead? */
        PZ_Unlock(cx->sessionLock);
    } else {
        PK11_ExitSlotMonitor(cx->slot);
    }
}

/*
 * Free up a Cipher Context
 */
void
PK11_DestroyContext(PK11Context *context, PRBool freeit)
{
    pk11_CloseSession(context->slot, context->session, context->ownSession);
    /* initialize the critical fields of the context */
    if (context->savedData != NULL)
        PORT_Free(context->savedData);
    if (context->key)
        PK11_FreeSymKey(context->key);
    if (context->param && context->param != &pk11_null_params)
        SECITEM_FreeItem(context->param, PR_TRUE);
    if (context->sessionLock)
        PZ_DestroyLock(context->sessionLock);
    PK11_FreeSlot(context->slot);
    if (freeit)
        PORT_Free(context);
}

/*
 * save the current context. Allocate Space if necessary.
 */
static unsigned char *
pk11_saveContextHelper(PK11Context *context, unsigned char *buffer,
                       unsigned long *savedLength)
{
    CK_RV crv;

    /* If buffer is NULL, this will get the length */
    crv = PK11_GETTAB(context->slot)->C_GetOperationState(context->session, (CK_BYTE_PTR)buffer, savedLength);
    if (!buffer || (crv == CKR_BUFFER_TOO_SMALL)) {
        /* the given buffer wasn't big enough (or was NULL), but we
         * have the length, so try again with a new buffer and the
         * correct length
         */
        unsigned long bufLen = *savedLength;
        buffer = PORT_Alloc(bufLen);
        if (buffer == NULL) {
            return (unsigned char *)NULL;
        }
        crv = PK11_GETTAB(context->slot)->C_GetOperationState(context->session, (CK_BYTE_PTR)buffer, savedLength);
        if (crv != CKR_OK) {
            PORT_ZFree(buffer, bufLen);
        }
    }
    if (crv != CKR_OK) {
        PORT_SetError(PK11_MapError(crv));
        return (unsigned char *)NULL;
    }
    return buffer;
}

void *
pk11_saveContext(PK11Context *context, void *space, unsigned long *savedLength)
{
    return pk11_saveContextHelper(context,
                                  (unsigned char *)space, savedLength);
}

/*
 * restore the current context
 */
SECStatus
pk11_restoreContext(PK11Context *context, void *space, unsigned long savedLength)
{
    CK_RV crv;
    CK_OBJECT_HANDLE objectID = (context->key) ? context->key->objectID : CK_INVALID_HANDLE;

    PORT_Assert(space != NULL);
    if (space == NULL) {
        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
        return SECFailure;
    }
    crv = PK11_GETTAB(context->slot)->C_SetOperationState(context->session, (CK_BYTE_PTR)space, savedLength, objectID, 0);
    if (crv != CKR_OK) {
        PORT_SetError(PK11_MapError(crv));
        return SECFailure;
    }
    return SECSuccess;
}

SECStatus pk11_Finalize(PK11Context *context);

/*
 * Context initialization. Used by all flavors of CreateContext
 */
static SECStatus
pk11_context_init(PK11Context *context, CK_MECHANISM *mech_info)
{
    CK_RV crv;
    PK11SymKey *symKey = context->key;
    SECStatus rv = SECSuccess;

    switch (context->operation) {
        case CKA_ENCRYPT:
            crv = PK11_GETTAB(context->slot)->C_EncryptInit(context->session, mech_info, symKey->objectID);
            break;
        case CKA_DECRYPT:
            if (context->fortezzaHack) {
                CK_ULONG count = 0;
                /* generate the IV for fortezza */
                crv = PK11_GETTAB(context->slot)->C_EncryptInit(context->session, mech_info, symKey->objectID);
                if (crv != CKR_OK)
                    break;
                PK11_GETTAB(context->slot)
                    ->C_EncryptFinal(context->session,
                                     NULL, &count);
            }
            crv = PK11_GETTAB(context->slot)->C_DecryptInit(context->session, mech_info, symKey->objectID);
            break;
        case CKA_SIGN:
            crv = PK11_GETTAB(context->slot)->C_SignInit(context->session, mech_info, symKey->objectID);
            break;
        case CKA_VERIFY:
            crv = PK11_GETTAB(context->slot)->C_SignInit(context->session, mech_info, symKey->objectID);
            break;
        case CKA_DIGEST:
            crv = PK11_GETTAB(context->slot)->C_DigestInit(context->session, mech_info);
            break;
        default:
            crv = CKR_OPERATION_NOT_INITIALIZED;
            break;
    }

    if (crv != CKR_OK) {
        PORT_SetError(PK11_MapError(crv));
        return SECFailure;
    }

    /*
     * handle session starvation case.. use our last session to multiplex
     */
    if (!context->ownSession) {
        context->savedData = pk11_saveContext(context, context->savedData,
                                              &context->savedLength);
        if (context->savedData == NULL)
            rv = SECFailure;
        /* clear out out session for others to use */
        pk11_Finalize(context);
    }
    return rv;
}

/*
 * Common Helper Function do come up with a new context.
 */
static PK11Context *
pk11_CreateNewContextInSlot(CK_MECHANISM_TYPE type,
                            PK11SlotInfo *slot, CK_ATTRIBUTE_TYPE operation, PK11SymKey *symKey,
                            SECItem *param)
{
    CK_MECHANISM mech_info;
    PK11Context *context;
    SECStatus rv;

    PORT_Assert(slot != NULL);
    if (!slot || (!symKey && ((operation != CKA_DIGEST) ||
                              (type == CKM_SKIPJACK_CBC64)))) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return NULL;
    }
    context = (PK11Context *)PORT_Alloc(sizeof(PK11Context));
    if (context == NULL) {
        return NULL;
    }

    /* now deal with the fortezza hack... the fortezza hack is an attempt
     * to get around the issue of the card not allowing you to do a FORTEZZA
     * LoadIV/Encrypt, which was added because such a combination could be
     * use to circumvent the key escrow system. Unfortunately SSL needs to
     * do this kind of operation, so in SSL we do a loadIV (to verify it),
     * Then GenerateIV, and through away the first 8 bytes on either side
     * of the connection.*/
    context->fortezzaHack = PR_FALSE;
    if (type == CKM_SKIPJACK_CBC64) {
        if (symKey->origin == PK11_OriginFortezzaHack) {
            context->fortezzaHack = PR_TRUE;
        }
    }

    /* initialize the critical fields of the context */
    context->operation = operation;
    context->key = symKey ? PK11_ReferenceSymKey(symKey) : NULL;
    context->slot = PK11_ReferenceSlot(slot);
    context->session = pk11_GetNewSession(slot, &context->ownSession);
    context->cx = symKey ? symKey->cx : NULL;
    /* get our session */
    context->savedData = NULL;

    /* save the parameters so that some digesting stuff can do multiple
     * begins on a single context */
    context->type = type;
    if (param) {
        if (param->len > 0) {
            context->param = SECITEM_DupItem(param);
        } else {
            context->param = (SECItem *)&pk11_null_params;
        }
    } else {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        context->param = NULL;
    }
    context->init = PR_FALSE;
    context->sessionLock = PZ_NewLock(nssILockPK11cxt);
    if ((context->param == NULL) || (context->sessionLock == NULL)) {
        PK11_DestroyContext(context, PR_TRUE);
        return NULL;
    }

    mech_info.mechanism = type;
    mech_info.pParameter = param->data;
    mech_info.ulParameterLen = param->len;
    PK11_EnterContextMonitor(context);
    rv = pk11_context_init(context, &mech_info);
    PK11_ExitContextMonitor(context);

    if (rv != SECSuccess) {
        PK11_DestroyContext(context, PR_TRUE);
        return NULL;
    }
    context->init = PR_TRUE;
    return context;
}

/*
 * put together the various PK11_Create_Context calls used by different
 * parts of libsec.
 */
PK11Context *
__PK11_CreateContextByRawKey(PK11SlotInfo *slot, CK_MECHANISM_TYPE type,
                             PK11Origin origin, CK_ATTRIBUTE_TYPE operation, SECItem *key,
                             SECItem *param, void *wincx)
{
    PK11SymKey *symKey = NULL;
    PK11Context *context = NULL;

    /* first get a slot */
    if (slot == NULL) {
        slot = PK11_GetBestSlot(type, wincx);
        if (slot == NULL) {
            PORT_SetError(SEC_ERROR_NO_MODULE);
            goto loser;
        }
    } else {
        PK11_ReferenceSlot(slot);
    }

    /* now import the key */
    symKey = PK11_ImportSymKey(slot, type, origin, operation, key, wincx);
    if (symKey == NULL)
        goto loser;

    context = PK11_CreateContextBySymKey(type, operation, symKey, param);

loser:
    if (symKey) {
        PK11_FreeSymKey(symKey);
    }
    if (slot) {
        PK11_FreeSlot(slot);
    }

    return context;
}

PK11Context *
PK11_CreateContextByRawKey(PK11SlotInfo *slot, CK_MECHANISM_TYPE type,
                           PK11Origin origin, CK_ATTRIBUTE_TYPE operation, SECItem *key,
                           SECItem *param, void *wincx)
{
    return __PK11_CreateContextByRawKey(slot, type, origin, operation,
                                        key, param, wincx);
}

/*
 * Create a context from a key. We really should make sure we aren't using
 * the same key in multiple session!
 */
PK11Context *
PK11_CreateContextBySymKey(CK_MECHANISM_TYPE type, CK_ATTRIBUTE_TYPE operation,
                           PK11SymKey *symKey, SECItem *param)
{
    PK11SymKey *newKey;
    PK11Context *context;

    /* if this slot doesn't support the mechanism, go to a slot that does */
    newKey = pk11_ForceSlot(symKey, type, operation);
    if (newKey == NULL) {
        PK11_ReferenceSymKey(symKey);
    } else {
        symKey = newKey;
    }

    /* Context Adopts the symKey.... */
    context = pk11_CreateNewContextInSlot(type, symKey->slot, operation, symKey,
                                          param);
    PK11_FreeSymKey(symKey);
    return context;
}

/*
 * Digest contexts don't need keys, but the do need to find a slot.
 * Macing should use PK11_CreateContextBySymKey.
 */
PK11Context *
PK11_CreateDigestContext(SECOidTag hashAlg)
{
    /* digesting has to work without authentication to the slot */
    CK_MECHANISM_TYPE type;
    PK11SlotInfo *slot;
    PK11Context *context;
    SECItem param;

    type = PK11_AlgtagToMechanism(hashAlg);
    slot = PK11_GetBestSlot(type, NULL);
    if (slot == NULL) {
        PORT_SetError(SEC_ERROR_NO_MODULE);
        return NULL;
    }

    /* maybe should really be PK11_GenerateNewParam?? */
    param.data = NULL;
    param.len = 0;
    param.type = 0;

    context = pk11_CreateNewContextInSlot(type, slot, CKA_DIGEST, NULL, &param);
    PK11_FreeSlot(slot);
    return context;
}

/*
 * create a new context which is the clone of the state of old context.
 */
PK11Context *
PK11_CloneContext(PK11Context *old)
{
    PK11Context *newcx;
    PRBool needFree = PR_FALSE;
    SECStatus rv = SECSuccess;
    void *data;
    unsigned long len;

    newcx = pk11_CreateNewContextInSlot(old->type, old->slot, old->operation,
                                        old->key, old->param);
    if (newcx == NULL)
        return NULL;

    /* now clone the save state. First we need to find the save state
      * of the old session. If the old context owns it's session,
      * the state needs to be saved, otherwise the state is in saveData. */
    if (old->ownSession) {
        PK11_EnterContextMonitor(old);
        data = pk11_saveContext(old, NULL, &len);
        PK11_ExitContextMonitor(old);
        needFree = PR_TRUE;
    } else {
        data = old->savedData;
        len = old->savedLength;
    }

    if (data == NULL) {
        PK11_DestroyContext(newcx, PR_TRUE);
        return NULL;
    }

    /* now copy that state into our new context. Again we have different
      * work if the new context owns it's own session. If it does, we
      * restore the state gathered above. If it doesn't, we copy the
      * saveData pointer... */
    if (newcx->ownSession) {
        PK11_EnterContextMonitor(newcx);
        rv = pk11_restoreContext(newcx, data, len);
        PK11_ExitContextMonitor(newcx);
    } else {
        PORT_Assert(newcx->savedData != NULL);
        if ((newcx->savedData == NULL) || (newcx->savedLength < len)) {
            PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
            rv = SECFailure;
        } else {
            PORT_Memcpy(newcx->savedData, data, len);
            newcx->savedLength = len;
        }
    }

    if (needFree)
        PORT_Free(data);

    if (rv != SECSuccess) {
        PK11_DestroyContext(newcx, PR_TRUE);
        return NULL;
    }
    return newcx;
}

/*
 * save the current context state into a variable. Required to make FORTEZZA
 * work.
 */
SECStatus
PK11_SaveContext(PK11Context *cx, unsigned char *save, int *len, int saveLength)
{
    unsigned char *data = NULL;
    CK_ULONG length = saveLength;

    if (cx->ownSession) {
        PK11_EnterContextMonitor(cx);
        data = pk11_saveContextHelper(cx, save, &length);
        PK11_ExitContextMonitor(cx);
        if (data)
            *len = length;
    } else if ((unsigned)saveLength >= cx->savedLength) {
        data = (unsigned char *)cx->savedData;
        if (cx->savedData) {
            PORT_Memcpy(save, cx->savedData, cx->savedLength);
        }
        *len = cx->savedLength;
    }
    if (data != NULL) {
        if (cx->ownSession) {
            PORT_ZFree(data, length);
        }
        return SECSuccess;
    } else {
        return SECFailure;
    }
}

/* same as above, but may allocate the return buffer. */
unsigned char *
PK11_SaveContextAlloc(PK11Context *cx,
                      unsigned char *preAllocBuf, unsigned int pabLen,
                      unsigned int *stateLen)
{
    unsigned char *stateBuf = NULL;
    unsigned long length = (unsigned long)pabLen;

    if (cx->ownSession) {
        PK11_EnterContextMonitor(cx);
        stateBuf = pk11_saveContextHelper(cx, preAllocBuf, &length);
        PK11_ExitContextMonitor(cx);
        *stateLen = (stateBuf != NULL) ? length : 0;
    } else {
        if (pabLen < cx->savedLength) {
            stateBuf = (unsigned char *)PORT_Alloc(cx->savedLength);
            if (!stateBuf) {
                return (unsigned char *)NULL;
            }
        } else {
            stateBuf = preAllocBuf;
        }
        if (cx->savedData) {
            PORT_Memcpy(stateBuf, cx->savedData, cx->savedLength);
        }
        *stateLen = cx->savedLength;
    }
    return stateBuf;
}

/*
 * restore the context state into a new running context. Also required for
 * FORTEZZA .
 */
SECStatus
PK11_RestoreContext(PK11Context *cx, unsigned char *save, int len)
{
    SECStatus rv = SECSuccess;
    if (cx->ownSession) {
        PK11_EnterContextMonitor(cx);
        pk11_Finalize(cx);
        rv = pk11_restoreContext(cx, save, len);
        PK11_ExitContextMonitor(cx);
    } else {
        PORT_Assert(cx->savedData != NULL);
        if ((cx->savedData == NULL) || (cx->savedLength < (unsigned)len)) {
            PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
            rv = SECFailure;
        } else {
            PORT_Memcpy(cx->savedData, save, len);
            cx->savedLength = len;
        }
    }
    return rv;
}

/*
 * This is  to get FIPS compliance until we can convert
 * libjar to use PK11_ hashing functions. It returns PR_FALSE
 * if we can't get a PK11 Context.
 */
PRBool
PK11_HashOK(SECOidTag algID)
{
    PK11Context *cx;

    cx = PK11_CreateDigestContext(algID);
    if (cx == NULL)
        return PR_FALSE;
    PK11_DestroyContext(cx, PR_TRUE);
    return PR_TRUE;
}

/*
 * start a new digesting or Mac'ing operation on this context
 */
SECStatus
PK11_DigestBegin(PK11Context *cx)
{
    CK_MECHANISM mech_info;
    SECStatus rv;

    if (cx->init == PR_TRUE) {
        return SECSuccess;
    }

    /*
     * make sure the old context is clear first
     */
    PK11_EnterContextMonitor(cx);
    pk11_Finalize(cx);

    mech_info.mechanism = cx->type;
    mech_info.pParameter = cx->param->data;
    mech_info.ulParameterLen = cx->param->len;
    rv = pk11_context_init(cx, &mech_info);
    PK11_ExitContextMonitor(cx);

    if (rv != SECSuccess) {
        return SECFailure;
    }
    cx->init = PR_TRUE;
    return SECSuccess;
}

SECStatus
PK11_HashBuf(SECOidTag hashAlg, unsigned char *out, const unsigned char *in,
             PRInt32 len)
{
    PK11Context *context;
    unsigned int max_length;
    unsigned int out_length;
    SECStatus rv;

    /* len will be passed to PK11_DigestOp as unsigned. */
    if (len < 0) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return SECFailure;
    }

    context = PK11_CreateDigestContext(hashAlg);
    if (context == NULL)
        return SECFailure;

    rv = PK11_DigestBegin(context);
    if (rv != SECSuccess) {
        PK11_DestroyContext(context, PR_TRUE);
        return rv;
    }

    rv = PK11_DigestOp(context, in, len);
    if (rv != SECSuccess) {
        PK11_DestroyContext(context, PR_TRUE);
        return rv;
    }

    /* XXX This really should have been an argument to this function! */
    max_length = HASH_ResultLenByOidTag(hashAlg);
    PORT_Assert(max_length);
    if (!max_length)
        max_length = HASH_LENGTH_MAX;

    rv = PK11_DigestFinal(context, out, &out_length, max_length);
    PK11_DestroyContext(context, PR_TRUE);
    return rv;
}

/*
 * execute a bulk encryption operation
 */
SECStatus
PK11_CipherOp(PK11Context *context, unsigned char *out, int *outlen,
              int maxout, const unsigned char *in, int inlen)
{
    CK_RV crv = CKR_OK;
    CK_ULONG length = maxout;
    CK_ULONG offset = 0;
    SECStatus rv = SECSuccess;
    unsigned char *saveOut = out;
    unsigned char *allocOut = NULL;

    /* if we ran out of session, we need to restore our previously stored
     * state.
     */
    PK11_EnterContextMonitor(context);
    if (!context->ownSession) {
        rv = pk11_restoreContext(context, context->savedData,
                                 context->savedLength);
        if (rv != SECSuccess) {
            PK11_ExitContextMonitor(context);
            return rv;
        }
    }

    /*
     * The fortezza hack is to send 8 extra bytes on the first encrypted and
     * lose them on the first decrypt.
     */
    if (context->fortezzaHack) {
        unsigned char random[8];
        if (context->operation == CKA_ENCRYPT) {
            PK11_ExitContextMonitor(context);
            rv = PK11_GenerateRandom(random, sizeof(random));
            PK11_EnterContextMonitor(context);

            /* since we are offseting the output, we can't encrypt back into
             * the same buffer... allocate a temporary buffer just for this
             * call. */
            allocOut = out = (unsigned char *)PORT_Alloc(maxout);
            if (out == NULL) {
                PK11_ExitContextMonitor(context);
                return SECFailure;
            }
            crv = PK11_GETTAB(context->slot)->C_EncryptUpdate(context->session, random, sizeof(random), out, &length);

            out += length;
            maxout -= length;
            offset = length;
        } else if (context->operation == CKA_DECRYPT) {
            length = sizeof(random);
            crv = PK11_GETTAB(context->slot)->C_DecryptUpdate(context->session, (CK_BYTE_PTR)in, sizeof(random), random, &length);
            inlen -= length;
            in += length;
            context->fortezzaHack = PR_FALSE;
        }
    }

    switch (context->operation) {
        case CKA_ENCRYPT:
            length = maxout;
            crv = PK11_GETTAB(context->slot)->C_EncryptUpdate(context->session, (CK_BYTE_PTR)in, inlen, out, &length);
            length += offset;
            break;
        case CKA_DECRYPT:
            length = maxout;
            crv = PK11_GETTAB(context->slot)->C_DecryptUpdate(context->session, (CK_BYTE_PTR)in, inlen, out, &length);
            break;
        default:
            crv = CKR_OPERATION_NOT_INITIALIZED;
            break;
    }

    if (crv != CKR_OK) {
        PORT_SetError(PK11_MapError(crv));
        *outlen = 0;
        rv = SECFailure;
    } else {
        *outlen = length;
    }

    if (context->fortezzaHack) {
        if (context->operation == CKA_ENCRYPT) {
            PORT_Assert(allocOut);
            PORT_Memcpy(saveOut, allocOut, length);
            PORT_Free(allocOut);
        }
        context->fortezzaHack = PR_FALSE;
    }

    /*
     * handle session starvation case.. use our last session to multiplex
     */
    if (!context->ownSession) {
        context->savedData = pk11_saveContext(context, context->savedData,
                                              &context->savedLength);
        if (context->savedData == NULL)
            rv = SECFailure;

        /* clear out out session for others to use */
        pk11_Finalize(context);
    }
    PK11_ExitContextMonitor(context);
    return rv;
}

/*
 * execute a digest/signature operation
 */
SECStatus
PK11_DigestOp(PK11Context *context, const unsigned char *in, unsigned inLen)
{
    CK_RV crv = CKR_OK;
    SECStatus rv = SECSuccess;

    if (inLen == 0) {
        return SECSuccess;
    }
    if (!in) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return SECFailure;
    }

    /* if we ran out of session, we need to restore our previously stored
     * state.
     */
    context->init = PR_FALSE;
    PK11_EnterContextMonitor(context);
    if (!context->ownSession) {
        rv = pk11_restoreContext(context, context->savedData,
                                 context->savedLength);
        if (rv != SECSuccess) {
            PK11_ExitContextMonitor(context);
            return rv;
        }
    }

    switch (context->operation) {
        /* also for MAC'ing */
        case CKA_SIGN:
            crv = PK11_GETTAB(context->slot)->C_SignUpdate(context->session, (unsigned char *)in, inLen);
            break;
        case CKA_VERIFY:
            crv = PK11_GETTAB(context->slot)->C_VerifyUpdate(context->session, (unsigned char *)in, inLen);
            break;
        case CKA_DIGEST:
            crv = PK11_GETTAB(context->slot)->C_DigestUpdate(context->session, (unsigned char *)in, inLen);
            break;
        default:
            crv = CKR_OPERATION_NOT_INITIALIZED;
            break;
    }

    if (crv != CKR_OK) {
        PORT_SetError(PK11_MapError(crv));
        rv = SECFailure;
    }

    /*
     * handle session starvation case.. use our last session to multiplex
     */
    if (!context->ownSession) {
        context->savedData = pk11_saveContext(context, context->savedData,
                                              &context->savedLength);
        if (context->savedData == NULL)
            rv = SECFailure;

        /* clear out out session for others to use */
        pk11_Finalize(context);
    }
    PK11_ExitContextMonitor(context);
    return rv;
}

/*
 * Digest a key if possible./
 */
SECStatus
PK11_DigestKey(PK11Context *context, PK11SymKey *key)
{
    CK_RV crv = CKR_OK;
    SECStatus rv = SECSuccess;
    PK11SymKey *newKey = NULL;

    if (!context || !key) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return SECFailure;
    }

    /* if we ran out of session, we need to restore our previously stored
     * state.
     */
    if (context->slot != key->slot) {
        newKey = pk11_CopyToSlot(context->slot, CKM_SSL3_SHA1_MAC, CKA_SIGN, key);
    } else {
        newKey = PK11_ReferenceSymKey(key);
    }

    context->init = PR_FALSE;
    PK11_EnterContextMonitor(context);
    if (!context->ownSession) {
        rv = pk11_restoreContext(context, context->savedData,
                                 context->savedLength);
        if (rv != SECSuccess) {
            PK11_ExitContextMonitor(context);
            PK11_FreeSymKey(newKey);
            return rv;
        }
    }

    if (newKey == NULL) {
        crv = CKR_KEY_TYPE_INCONSISTENT;
        if (key->data.data) {
            crv = PK11_GETTAB(context->slot)->C_DigestUpdate(context->session, key->data.data, key->data.len);
        }
    } else {
        crv = PK11_GETTAB(context->slot)->C_DigestKey(context->session, newKey->objectID);
    }

    if (crv != CKR_OK) {
        PORT_SetError(PK11_MapError(crv));
        rv = SECFailure;
    }

    /*
     * handle session starvation case.. use our last session to multiplex
     */
    if (!context->ownSession) {
        context->savedData = pk11_saveContext(context, context->savedData,
                                              &context->savedLength);
        if (context->savedData == NULL)
            rv = SECFailure;

        /* clear out out session for others to use */
        pk11_Finalize(context);
    }
    PK11_ExitContextMonitor(context);
    if (newKey)
        PK11_FreeSymKey(newKey);
    return rv;
}

/*
 * externally callable version of the lowercase pk11_finalize().
 */
SECStatus
PK11_Finalize(PK11Context *context)
{
    SECStatus rv;

    PK11_EnterContextMonitor(context);
    rv = pk11_Finalize(context);
    PK11_ExitContextMonitor(context);
    return rv;
}

/*
 * clean up a cipher operation, so the session can be used by
 * someone new.
 */
SECStatus
pk11_Finalize(PK11Context *context)
{
    CK_ULONG count = 0;
    CK_RV crv;
    unsigned char stackBuf[256];
    unsigned char *buffer = NULL;

    if (!context->ownSession) {
        return SECSuccess;
    }

finalize:
    switch (context->operation) {
        case CKA_ENCRYPT:
            crv = PK11_GETTAB(context->slot)->C_EncryptFinal(context->session, buffer, &count);
            break;
        case CKA_DECRYPT:
            crv = PK11_GETTAB(context->slot)->C_DecryptFinal(context->session, buffer, &count);
            break;
        case CKA_SIGN:
            crv = PK11_GETTAB(context->slot)->C_SignFinal(context->session, buffer, &count);
            break;
        case CKA_VERIFY:
            crv = PK11_GETTAB(context->slot)->C_VerifyFinal(context->session, buffer, count);
            break;
        case CKA_DIGEST:
            crv = PK11_GETTAB(context->slot)->C_DigestFinal(context->session, buffer, &count);
            break;
        default:
            crv = CKR_OPERATION_NOT_INITIALIZED;
            break;
    }

    if (crv != CKR_OK) {
        if (buffer != stackBuf) {
            PORT_Free(buffer);
        }
        if (crv == CKR_OPERATION_NOT_INITIALIZED) {
            /* if there's no operation, it is finalized */
            return SECSuccess;
        }
        PORT_SetError(PK11_MapError(crv));
        return SECFailure;
    }

    /* try to finalize the session with a buffer */
    if (buffer == NULL) {
        if (count <= sizeof stackBuf) {
            buffer = stackBuf;
        } else {
            buffer = PORT_Alloc(count);
            if (buffer == NULL) {
                PORT_SetError(SEC_ERROR_NO_MEMORY);
                return SECFailure;
            }
        }
        goto finalize;
    }
    if (buffer != stackBuf) {
        PORT_Free(buffer);
    }
    return SECSuccess;
}

/*
 *  Return the final digested or signed data...
 *  this routine can either take pre initialized data, or allocate data
 *  either out of an arena or out of the standard heap.
 */
SECStatus
PK11_DigestFinal(PK11Context *context, unsigned char *data,
                 unsigned int *outLen, unsigned int length)
{
    CK_ULONG len;
    CK_RV crv;
    SECStatus rv;

    /* if we ran out of session, we need to restore our previously stored
     * state.
     */
    PK11_EnterContextMonitor(context);
    if (!context->ownSession) {
        rv = pk11_restoreContext(context, context->savedData,
                                 context->savedLength);
        if (rv != SECSuccess) {
            PK11_ExitContextMonitor(context);
            return rv;
        }
    }

    len = length;
    switch (context->operation) {
        case CKA_SIGN:
            crv = PK11_GETTAB(context->slot)->C_SignFinal(context->session, data, &len);
            break;
        case CKA_VERIFY:
            crv = PK11_GETTAB(context->slot)->C_VerifyFinal(context->session, data, len);
            break;
        case CKA_DIGEST:
            crv = PK11_GETTAB(context->slot)->C_DigestFinal(context->session, data, &len);
            break;
        case CKA_ENCRYPT:
            crv = PK11_GETTAB(context->slot)->C_EncryptFinal(context->session, data, &len);
            break;
        case CKA_DECRYPT:
            crv = PK11_GETTAB(context->slot)->C_DecryptFinal(context->session, data, &len);
            break;
        default:
            crv = CKR_OPERATION_NOT_INITIALIZED;
            break;
    }
    PK11_ExitContextMonitor(context);

    *outLen = (unsigned int)len;
    context->init = PR_FALSE; /* allow Begin to start up again */

    if (crv != CKR_OK) {
        PORT_SetError(PK11_MapError(crv));
        return SECFailure;
    }
    return SECSuccess;
}