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fwknop/lib/fko_funcs.c
Michael Rash ba3b7d1d11 Bug fix for multi-stanza key use and replay attack detection 
This commit fixes a bug where the same encryption key used for two stanzas in
the access.conf file would result in access requests that matched the second
stanza to always be treated as a replay attack.  This has been fixed for
the fwknop-2.0.1 release, and was reported by Andy Rowland.  Now the fwknopd
server computes the SHA256 digest of raw incoming payload data before
decryption, and compares this against all previous hashes.  Previous to this
commit, fwknopd would add a new hash to the replay digest list right after
the first access.conf stanza match, so when SPA packet data matched the
second access.conf stanza a matching replay digest would already be there.
2012-07-07 21:31:30 -04:00

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/*
*****************************************************************************
*
* File: fko_funcs.c
*
* Author: Damien S. Stuart
*
* Purpose: General utility functions for libfko
*
* Copyright 2009-2010 Damien Stuart (dstuart@dstuart.org)
*
* License (GNU Public License):
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*
*****************************************************************************
*/
#include "fko_common.h"
#include "fko.h"
#include "cipher_funcs.h"
/* Initialize an fko context.
*/
int
fko_new(fko_ctx_t *r_ctx)
{
fko_ctx_t ctx;
int res;
char *ver;
ctx = calloc(1, sizeof *ctx);
if(ctx == NULL)
return(FKO_ERROR_MEMORY_ALLOCATION);
/* Set default values and state.
*
* Note: We have to explicitly set the ctx->state to initialized
* just before making an fko_xxx function call, then set it
* back to zero just afer. During initialization, we need
* to make these functions think they are operating on an
* initialized context, or else they would fail.
*/
/* Set the version string.
*/
ctx->initval = FKO_CTX_INITIALIZED;
ver = strdup(FKO_PROTOCOL_VERSION);
ctx->initval = 0;
if(ver == NULL)
{
free(ctx);
return(FKO_ERROR_MEMORY_ALLOCATION);
}
ctx->version = ver;
/* Rand value.
*/
ctx->initval = FKO_CTX_INITIALIZED;
res = fko_set_rand_value(ctx, NULL);
ctx->initval = 0;
if(res != FKO_SUCCESS)
{
fko_destroy(ctx);
return res;
}
/* Username.
*/
ctx->initval = FKO_CTX_INITIALIZED;
res = fko_set_username(ctx, NULL);
ctx->initval = 0;
if(res != FKO_SUCCESS)
{
fko_destroy(ctx);
return res;
}
/* Timestamp.
*/
ctx->initval = FKO_CTX_INITIALIZED;
res = fko_set_timestamp(ctx, 0);
ctx->initval = 0;
if(res != FKO_SUCCESS)
{
fko_destroy(ctx);
return res;
}
/* Default Digest Type.
*/
ctx->initval = FKO_CTX_INITIALIZED;
res = fko_set_spa_digest_type(ctx, FKO_DEFAULT_DIGEST);
ctx->initval = 0;
if(res != FKO_SUCCESS)
{
fko_destroy(ctx);
return res;
}
/* Default Message Type.
*/
ctx->initval = FKO_CTX_INITIALIZED;
res = fko_set_spa_message_type(ctx, FKO_DEFAULT_MSG_TYPE);
ctx->initval = 0;
if(res != FKO_SUCCESS)
{
fko_destroy(ctx);
return res;
}
/* Default Encryption Type.
*/
ctx->initval = FKO_CTX_INITIALIZED;
res = fko_set_spa_encryption_type(ctx, FKO_DEFAULT_ENCRYPTION);
ctx->initval = 0;
if(res != FKO_SUCCESS)
{
fko_destroy(ctx);
return res;
}
#if HAVE_LIBGPGME
/* Set gpg signature verify on.
*/
ctx->verify_gpg_sigs = 1;
#endif /* HAVE_LIBGPGME */
/* Now we mean it.
*/
ctx->initval = FKO_CTX_INITIALIZED;
FKO_SET_CTX_INITIALIZED(ctx);
*r_ctx = ctx;
return(FKO_SUCCESS);
}
/* Initialize an fko context with external (encrypted/encoded) data.
* This is used to create a context with the purpose of decoding
* and parsing the provided data into the context data.
*/
int
fko_new_with_data(fko_ctx_t *r_ctx, const char *enc_msg, const char *dec_key)
{
fko_ctx_t ctx;
int res = FKO_SUCCESS; /* Are we optimistic or what? */
ctx = calloc(1, sizeof *ctx);
if(ctx == NULL)
return(FKO_ERROR_MEMORY_ALLOCATION);
/* First, add the data to the context.
*/
ctx->encrypted_msg = strdup(enc_msg);
if(ctx->encrypted_msg == NULL)
{
free(ctx);
return(FKO_ERROR_MEMORY_ALLOCATION);
}
/* Consider it initialized here.
*/
ctx->initval = FKO_CTX_INITIALIZED;
FKO_SET_CTX_INITIALIZED(ctx);
/* If a decryption password is provided, go ahead and decrypt and
* decode.
*/
if(dec_key != NULL)
{
res = fko_decrypt_spa_data(ctx, dec_key);
if(res != FKO_SUCCESS)
{
fko_destroy(ctx);
*r_ctx = NULL; /* Make sure the caller ctx is null just in case */
return(res);
}
}
#if HAVE_LIBGPGME
/* Set gpg signature verify on.
*/
ctx->verify_gpg_sigs = 1;
#endif /* HAVE_LIBGPGME */
*r_ctx = ctx;
return(res);
}
/* Destroy a context and free its resources
*/
void
fko_destroy(fko_ctx_t ctx)
{
#if HAVE_LIBGPGME
fko_gpg_sig_t gsig, tgsig;
#endif
if(CTX_INITIALIZED(ctx))
{
if(ctx->rand_val != NULL)
free(ctx->rand_val);
if(ctx->username != NULL)
free(ctx->username);
if(ctx->version != NULL)
free(ctx->version);
if(ctx->message != NULL)
free(ctx->message);
if(ctx->nat_access != NULL)
free(ctx->nat_access);
if(ctx->server_auth != NULL)
free(ctx->server_auth);
if(ctx->digest != NULL)
free(ctx->digest);
if(ctx->raw_digest != NULL)
free(ctx->raw_digest);
if(ctx->encoded_msg != NULL)
free(ctx->encoded_msg);
if(ctx->encrypted_msg != NULL)
free(ctx->encrypted_msg);
#if HAVE_LIBGPGME
if(ctx->gpg_exe != NULL)
free(ctx->gpg_exe);
if(ctx->gpg_home_dir != NULL)
free(ctx->gpg_home_dir);
if(ctx->gpg_recipient != NULL)
free(ctx->gpg_recipient);
if(ctx->gpg_signer != NULL)
free(ctx->gpg_signer);
if(ctx->recipient_key != NULL)
{
gpgme_key_unref(ctx->recipient_key);
}
if(ctx->signer_key != NULL)
{
gpgme_key_unref(ctx->signer_key);
}
if(ctx->gpg_ctx != NULL)
gpgme_release(ctx->gpg_ctx);
gsig = ctx->gpg_sigs;
while(gsig != NULL)
{
if(gsig->fpr != NULL)
free(gsig->fpr);
tgsig = gsig;
gsig = gsig->next;
free(tgsig);
}
#endif /* HAVE_LIBGPGME */
bzero(ctx, sizeof(*ctx));
}
free(ctx);
}
/* Return the fko version
*/
int
fko_get_version(fko_ctx_t ctx, char **version)
{
/* Must be initialized
*/
if(!CTX_INITIALIZED(ctx))
return(FKO_ERROR_CTX_NOT_INITIALIZED);
*version = ctx->version;
return(FKO_SUCCESS);
}
/* Final update and encoding of data in the context.
* This does require all requisite fields be properly
* set.
*/
int
fko_spa_data_final(fko_ctx_t ctx, const char *enc_key)
{
/* Must be initialized
*/
if(!CTX_INITIALIZED(ctx))
return(FKO_ERROR_CTX_NOT_INITIALIZED);
return(fko_encrypt_spa_data(ctx, enc_key));
}
/* Return the fko SPA encrypted data.
*/
int
fko_get_spa_data(fko_ctx_t ctx, char **spa_data)
{
/* Must be initialized
*/
if(!CTX_INITIALIZED(ctx))
return(FKO_ERROR_CTX_NOT_INITIALIZED);
/* We expect to have encrypted data to process. If not, we bail.
*/
if(ctx->encrypted_msg == NULL || (strlen(ctx->encrypted_msg) < 1))
return(FKO_ERROR_MISSING_ENCODED_DATA);
*spa_data = ctx->encrypted_msg;
/* Notice we omit the first 10 bytes if Rijndael encryption is
* used (to eliminate the consistent 'Salted__' string), and
* in GnuPG mode we eliminate the consistent 'hQ' base64 encoded
* prefix
*/
if(ctx->encryption_type == FKO_ENCRYPTION_RIJNDAEL)
*spa_data += strlen(B64_RIJNDAEL_SALT);
else if(ctx->encryption_type == FKO_ENCRYPTION_GPG)
*spa_data += strlen(B64_GPG_PREFIX);
return(FKO_SUCCESS);
}
/* Set the fko SPA encrypted data.
*/
int
fko_set_spa_data(fko_ctx_t ctx, const char *enc_msg)
{
/* Must be initialized
*/
if(!CTX_INITIALIZED(ctx))
return FKO_ERROR_CTX_NOT_INITIALIZED;
/* First, add the data to the context.
*/
ctx->encrypted_msg = strdup(enc_msg);
if(ctx->encrypted_msg == NULL)
return(FKO_ERROR_MEMORY_ALLOCATION);
return(FKO_SUCCESS);
}
/***EOF***/
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