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Parse PEM RSA keys ourself, and use libgcrypt to do RSA encryption and decryption.

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This commit is contained in:
Guus Sliepen 2007-05-20 22:28:49 +00:00
parent fbf305c09d
commit 465837dd7f
7 changed files with 355 additions and 129 deletions
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1
configure.in
View file

@ -145,6 +145,7 @@ AC_CACHE_SAVE
dnl These are defined in files in m4/
AM_PATH_LIBGCRYPT([], [], [AC_MSG_ERROR([Libgcrypt not found.]); break])
tinc_OPENSSL
tinc_ZLIB
tinc_LZO

8
src/Makefile.am
View file

@ -7,7 +7,7 @@ EXTRA_DIST = linux/device.c bsd/device.c solaris/device.c cygwin/device.c mingw/
tincd_SOURCES = conf.c connection.c control.c edge.c graph.c logger.c meta.c net.c net_packet.c net_setup.c \
net_socket.c netutl.c node.c process.c protocol.c protocol_auth.c protocol_edge.c protocol_misc.c \
protocol_key.c protocol_subnet.c route.c subnet.c tincd.c
protocol_key.c protocol_subnet.c route.c rsa.c subnet.c tincd.c
tincctl_SOURCES = tincctl.c
@ -18,12 +18,13 @@ DEFAULT_INCLUDES =
INCLUDES = @INCLUDES@ -I$(top_builddir) -I$(top_srcdir)/lib
noinst_HEADERS = conf.h connection.h control.h device.h edge.h graph.h logger.h meta.h net.h netutl.h node.h process.h \
protocol.h route.h subnet.h
protocol.h route.h rsa.h subnet.h
LIBS = @LIBS@ @LIBINTL@
tincd_LDADD = \
$(top_builddir)/lib/libvpn.a
$(top_builddir)/lib/libvpn.a \
$(LIBGCRYPT_LIBS)
tincctl_LDADD = \
$(top_builddir)/lib/libvpn.a
@ -31,6 +32,7 @@ tincctl_LDADD = \
localedir = $(datadir)/locale
AM_CFLAGS = @CFLAGS@ -DCONFDIR=\"$(sysconfdir)\" -DLOCALEDIR=\"$(localedir)\" -DLOCALSTATEDIR=\"$(localstatedir)\"
tinc_CPPFLAGS = $(LIBGCRYPT_CFLAGS)
dist-hook:
rm -f `find . -type l`

6
src/connection.h
View file

@ -23,11 +23,12 @@
#ifndef __TINC_CONNECTION_H__
#define __TINC_CONNECTION_H__
#include <openssl/rsa.h>
//#include <openssl/rsa.h>
#include <openssl/evp.h>
#include <event.h>
#include "rsa.h"
#include "splay_tree.h"
#define OPTION_INDIRECT 0x0001
@ -72,7 +73,8 @@ typedef struct connection_t {
struct node_t *node; /* node associated with the other end */
struct edge_t *edge; /* edge associated with this connection */
RSA *rsa_key; /* his public/private key */
//RSA *rsa_key; /* his public/private key */
struct rsa_key_t rsa_key; /* his public/private key */
const EVP_CIPHER *incipher; /* Cipher he will use to send data to us */
const EVP_CIPHER *outcipher; /* Cipher we will use to send data to him */
EVP_CIPHER_CTX *inctx; /* Context of encrypted meta data that will come from him to us */

128
src/net_setup.c
View file

@ -22,6 +22,8 @@
#include "system.h"
#include <gcrypt.h>
#include <openssl/pem.h>
#include <openssl/rsa.h>
#include <openssl/rand.h>
@ -40,6 +42,7 @@
#include "process.h"
#include "protocol.h"
#include "route.h"
#include "rsa.h"
#include "subnet.h"
#include "utils.h"
#include "xalloc.h"
@ -50,27 +53,13 @@ static struct event device_ev;
bool read_rsa_public_key(connection_t *c) {
FILE *fp;
char *fname;
char *key;
bool result;
cp();
if(!c->rsa_key) {
c->rsa_key = RSA_new();
// RSA_blinding_on(c->rsa_key, NULL);
}
if(!get_config_string(lookup_config(c->config_tree, "PublicKeyFile"), &fname))
asprintf(&fname, "%s/hosts/%s", confbase, c->name);
/* First, check for simple PublicKey statement */
if(get_config_string(lookup_config(c->config_tree, "PublicKey"), &key)) {
BN_hex2bn(&c->rsa_key->n, key);
BN_hex2bn(&c->rsa_key->e, "FFFF");
free(key);
return true;
}
/* Else, check for PublicKeyFile statement and read it */
if(get_config_string(lookup_config(c->config_tree, "PublicKeyFile"), &fname)) {
fp = fopen(fname, "r");
if(!fp) {
@ -80,95 +69,22 @@ bool read_rsa_public_key(connection_t *c) {
return false;
}
free(fname);
c->rsa_key = PEM_read_RSAPublicKey(fp, &c->rsa_key, NULL, NULL);
result = read_pem_rsa_public_key(fp, &c->rsa_key);
fclose(fp);
if(c->rsa_key)
return true; /* Woohoo. */
/* If it fails, try PEM_read_RSA_PUBKEY. */
fp = fopen(fname, "r");
if(!fp) {
logger(LOG_ERR, _("Error reading RSA public key file `%s': %s"),
fname, strerror(errno));
if(!result)
logger(LOG_ERR, _("Reading RSA public key file `%s' failed: %s"), fname, strerror(errno));
free(fname);
return false;
return result;
}
free(fname);
c->rsa_key = PEM_read_RSA_PUBKEY(fp, &c->rsa_key, NULL, NULL);
fclose(fp);
if(c->rsa_key) {
// RSA_blinding_on(c->rsa_key, NULL);
return true;
}
logger(LOG_ERR, _("Reading RSA public key file `%s' failed: %s"),
fname, strerror(errno));
return false;
}
/* Else, check if a harnessed public key is in the config file */
asprintf(&fname, "%s/hosts/%s", confbase, c->name);
fp = fopen(fname, "r");
if(fp) {
c->rsa_key = PEM_read_RSAPublicKey(fp, &c->rsa_key, NULL, NULL);
fclose(fp);
}
free(fname);
if(c->rsa_key)
return true;
/* Try again with PEM_read_RSA_PUBKEY. */
asprintf(&fname, "%s/hosts/%s", confbase, c->name);
fp = fopen(fname, "r");
if(fp) {
c->rsa_key = PEM_read_RSA_PUBKEY(fp, &c->rsa_key, NULL, NULL);
// RSA_blinding_on(c->rsa_key, NULL);
fclose(fp);
}
free(fname);
if(c->rsa_key)
return true;
logger(LOG_ERR, _("No public key for %s specified!"), c->name);
return false;
}
bool read_rsa_private_key(void) {
bool read_rsa_private_key() {
FILE *fp;
char *fname, *key, *pubkey;
struct stat s;
char *fname;
bool result;
cp();
if(get_config_string(lookup_config(config_tree, "PrivateKey"), &key)) {
if(!get_config_string(lookup_config(myself->connection->config_tree, "PublicKey"), &pubkey)) {
logger(LOG_ERR, _("PrivateKey used but no PublicKey found!"));
return false;
}
myself->connection->rsa_key = RSA_new();
// RSA_blinding_on(myself->connection->rsa_key, NULL);
BN_hex2bn(&myself->connection->rsa_key->d, key);
BN_hex2bn(&myself->connection->rsa_key->n, pubkey);
BN_hex2bn(&myself->connection->rsa_key->e, "FFFF");
free(key);
free(pubkey);
return true;
}
if(!get_config_string(lookup_config(config_tree, "PrivateKeyFile"), &fname))
asprintf(&fname, "%s/rsa_key.priv", confbase);
@ -182,9 +98,10 @@ bool read_rsa_private_key(void) {
}
#if !defined(HAVE_MINGW) && !defined(HAVE_CYGWIN)
struct stat s;
if(fstat(fileno(fp), &s)) {
logger(LOG_ERR, _("Could not stat RSA private key file `%s': %s'"),
fname, strerror(errno));
logger(LOG_ERR, _("Could not stat RSA private key file `%s': %s'"), fname, strerror(errno));
free(fname);
return false;
}
@ -193,18 +110,13 @@ bool read_rsa_private_key(void) {
logger(LOG_WARNING, _("Warning: insecure file permissions for RSA private key file `%s'!"), fname);
#endif
myself->connection->rsa_key = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
result = read_pem_rsa_private_key(fp, &myself->connection->rsa_key);
fclose(fp);
if(!myself->connection->rsa_key) {
logger(LOG_ERR, _("Reading RSA private key file `%s' failed: %s"),
fname, strerror(errno));
if(!result)
logger(LOG_ERR, _("Reading RSA private key file `%s' failed: %s"), fname, strerror(errno));
free(fname);
return false;
}
free(fname);
return true;
return result;
}
static struct event keyexpire_event;

22
src/protocol_auth.c
View file

@ -37,6 +37,7 @@
#include "netutl.h"
#include "node.h"
#include "protocol.h"
#include "rsa.h"
#include "utils.h"
#include "xalloc.h"
@ -116,12 +117,12 @@ bool id_h(connection_t *c, char *request) {
bool send_metakey(connection_t *c) {
char *buffer;
int len;
unsigned int len;
bool x;
cp();
len = RSA_size(c->rsa_key);
len = get_rsa_size(&c->rsa_key);
/* Allocate buffers for the meta key */
@ -163,7 +164,7 @@ bool send_metakey(connection_t *c) {
with a length equal to that of the modulus of the RSA key.
*/
if(RSA_public_encrypt(len, (unsigned char *)c->outkey, (unsigned char *)buffer, c->rsa_key, RSA_NO_PADDING) != len) {
if(!rsa_public_encrypt(len, (unsigned char *)c->outkey, (unsigned char *)buffer, &c->rsa_key)) {
logger(LOG_ERR, _("Error during encryption of meta key for %s (%s)"),
c->name, c->hostname);
return false;
@ -212,7 +213,7 @@ bool metakey_h(connection_t *c, char *request) {
return false;
}
len = RSA_size(myself->connection->rsa_key);
len = get_rsa_size(&myself->connection->rsa_key);
/* Check if the length of the meta key is all right */
@ -235,9 +236,8 @@ bool metakey_h(connection_t *c, char *request) {
/* Decrypt the meta key */
if(RSA_private_decrypt(len, (unsigned char *)buffer, (unsigned char *)c->inkey, myself->connection->rsa_key, RSA_NO_PADDING) != len) { /* See challenge() */
logger(LOG_ERR, _("Error during encryption of meta key for %s (%s)"),
c->name, c->hostname);
if(!rsa_private_decrypt(len, (unsigned char *)buffer, (unsigned char *)c->inkey, &myself->connection->rsa_key)) {
logger(LOG_ERR, _("Error during encryption of meta key for %s (%s)"), c->name, c->hostname);
return false;
}
@ -306,7 +306,7 @@ bool send_challenge(connection_t *c) {
/* CHECKME: what is most reasonable value for len? */
len = RSA_size(c->rsa_key);
len = get_rsa_size(&c->rsa_key);
/* Allocate buffers for the challenge */
@ -341,7 +341,7 @@ bool challenge_h(connection_t *c, char *request) {
return false;
}
len = RSA_size(myself->connection->rsa_key);
len = get_rsa_size(&myself->connection->rsa_key);
/* Check if the length of the challenge is all right */
@ -376,7 +376,7 @@ bool send_chal_reply(connection_t *c) {
/* Calculate the hash from the challenge we received */
if(!EVP_DigestInit(&ctx, c->indigest)
|| !EVP_DigestUpdate(&ctx, c->mychallenge, RSA_size(myself->connection->rsa_key))
|| !EVP_DigestUpdate(&ctx, c->mychallenge, get_rsa_size(&myself->connection->rsa_key))
|| !EVP_DigestFinal(&ctx, (unsigned char *)hash, NULL)) {
logger(LOG_ERR, _("Error during calculation of response for %s (%s): %s"),
c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
@ -421,7 +421,7 @@ bool chal_reply_h(connection_t *c, char *request) {
/* Calculate the hash from the challenge we sent */
if(!EVP_DigestInit(&ctx, c->outdigest)
|| !EVP_DigestUpdate(&ctx, c->hischallenge, RSA_size(c->rsa_key))
|| !EVP_DigestUpdate(&ctx, c->hischallenge, get_rsa_size(&c->rsa_key))
|| !EVP_DigestFinal(&ctx, (unsigned char *)myhash, NULL)) {
logger(LOG_ERR, _("Error during calculation of response from %s (%s): %s"),
c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));

269
src/rsa.c Normal file
View file

@ -0,0 +1,269 @@
/*
rsa.c -- RSA key handling
Copyright (C) 2007 Guus Sliepen <guus@tinc-vpn.org>
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., 675 Mass Ave, Cambridge, MA 02139, USA.
$Id$
*/
#include "system.h"
#include <gcrypt.h>
#include "logger.h"
#include "rsa.h"
// Base64 encoding/decoding tables
static const uint8_t b64d[128] = {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f,
0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
0x3a, 0x3b, 0x3c, 0x3d, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c,
0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12,
0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
0x19, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e,
0x1f, 0x20, 0x21, 0x22, 0x23, 0x24,
0x25, 0x26, 0x27, 0x28, 0x29, 0x2a,
0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
0x31, 0x32, 0x33, 0xff, 0xff, 0xff,
0xff, 0xff
};
static const char b64e[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
// PEM encoding/decoding functions
static bool pem_decode(FILE *fp, const char *header, uint8_t *buf, size_t size, size_t *outsize) {
bool decode = false;
char line[1024];
uint16_t word = 0;
int shift = 10;
size_t i, j = 0;
while(!feof(fp)) {
if(!fgets(line, sizeof line, fp))
return false;
if(!decode && !strncmp(line, "-----BEGIN ", 11)) {
if(!strncmp(line + 11, header, strlen(header)))
decode = true;
continue;
}
if(decode && !strncmp(line, "-----END", 8)) {
break;
}
if(!decode)
continue;
for(i = 0; line[i] >= ' '; i++) {
if(line[i] >= 128 || line[i] < 0 || b64d[(int)line[i]] == 0xff)
break;
word |= b64d[(int)line[i]] << shift;
shift -= 6;
if(shift <= 2) {
if(j > size) {
errno = ENOMEM;
return false;
}
buf[j++] = word >> 8;
word <<= 8;
shift += 8;
}
}
}
if(outsize)
*outsize = j;
return true;
}
// BER decoding functions
static int ber_read_id(unsigned char **p, size_t *buflen) {
if(*buflen <= 0)
return -1;
if((**p & 0x1f) == 0x1f) {
int id = 0;
bool more;
while(*buflen > 0) {
id <<= 7;
id |= **p & 0x7f;
more = *(*p)++ & 0x80;
(*buflen)--;
if(!more)
break;
}
return id;
} else {
(*buflen)--;
return *(*p)++ & 0x1f;
}
}
static size_t ber_read_len(unsigned char **p, size_t *buflen) {
if(*buflen <= 0)
return -1;
if(**p & 0x80) {
size_t result = 0;
int len = *(*p)++ & 0x7f;
(*buflen)--;
if(len > *buflen)
return 0;
while(len--) {
result <<= 8;
result |= *(*p)++;
(*buflen)--;
}
return result;
} else {
(*buflen)--;
return *(*p)++;
}
}
static bool ber_read_sequence(unsigned char **p, size_t *buflen, size_t *result) {
int tag = ber_read_id(p, buflen);
size_t len = ber_read_len(p, buflen);
if(tag == 0x10) {
if(result)
*result = len;
return true;
} else {
return false;
}
}
static bool ber_read_mpi(unsigned char **p, size_t *buflen, gcry_mpi_t *mpi) {
int tag = ber_read_id(p, buflen);
size_t len = ber_read_len(p, buflen);
gcry_error_t err = 0;
if(tag != 0x02 || len > *buflen)
return false;
if(mpi)
err = gcry_mpi_scan(mpi, GCRYMPI_FMT_USG, *p, len, NULL);
*p += len;
*buflen -= len;
return mpi ? !err : true;
}
// Read PEM RSA keys
bool read_pem_rsa_public_key(FILE *fp, rsa_key_t *key) {
uint8_t derbuf[8096], *derp = derbuf;
size_t derlen;
if(!pem_decode(fp, "RSA PUBLIC KEY", derbuf, sizeof derbuf, &derlen)) {
logger(LOG_ERR, _("Unable to read RSA public key: %s"), strerror(errno));
return NULL;
}
if(!ber_read_sequence(&derp, &derlen, NULL)
|| !ber_read_mpi(&derp, &derlen, &key->n)
|| !ber_read_mpi(&derp, &derlen, &key->e)
|| derlen) {
logger(LOG_ERR, _("Error while decoding RSA public key"));
return NULL;
}
return true;
}
bool read_pem_rsa_private_key(FILE *fp, rsa_key_t *key) {
uint8_t derbuf[8096], *derp = derbuf;
size_t derlen;
if(!pem_decode(fp, "RSA PRIVATE KEY", derbuf, sizeof derbuf, &derlen)) {
logger(LOG_ERR, _("Unable to read RSA private key: %s"), strerror(errno));
return NULL;
}
if(!ber_read_sequence(&derp, &derlen, NULL)
|| !ber_read_mpi(&derp, &derlen, NULL)
|| !ber_read_mpi(&derp, &derlen, &key->n)
|| !ber_read_mpi(&derp, &derlen, &key->e)
|| !ber_read_mpi(&derp, &derlen, &key->d)
|| !ber_read_mpi(&derp, &derlen, NULL) // p
|| !ber_read_mpi(&derp, &derlen, NULL) // q
|| !ber_read_mpi(&derp, &derlen, NULL)
|| !ber_read_mpi(&derp, &derlen, NULL)
|| !ber_read_mpi(&derp, &derlen, NULL) // u
|| derlen) {
logger(LOG_ERR, _("Error while decoding RSA private key"));
return NULL;
}
return true;
}
unsigned int get_rsa_size(rsa_key_t *key) {
return (gcry_mpi_get_nbits(key->n) + 7) / 8;
}
/* Well, libgcrypt has functions to handle RSA keys, but they suck.
* So we just use libgcrypt's mpi functions, and do the math ourselves.
*/
// TODO: get rid of this macro, properly clean up gcry_ structures after use
#define check(foo) { gcry_error_t err = (foo); if(err) {logger(LOG_ERR, "gcrypt error %s/%s at %s:%d\n", gcry_strsource(err), gcry_strerror(err), __FILE__, __LINE__); return false; }}
bool rsa_public_encrypt(size_t len, void *in, void *out, rsa_key_t *key) {
gcry_mpi_t inmpi;
check(gcry_mpi_scan(&inmpi, GCRYMPI_FMT_USG, in, len, NULL));
gcry_mpi_t outmpi = gcry_mpi_new(len * 8);
gcry_mpi_powm(outmpi, inmpi, key->e, key->n);
check(gcry_mpi_print(GCRYMPI_FMT_USG, out,len, NULL, outmpi));
return true;
}
bool rsa_private_decrypt(size_t len, void *in, void *out, rsa_key_t *key) {
gcry_mpi_t inmpi;
check(gcry_mpi_scan(&inmpi, GCRYMPI_FMT_USG, in, len, NULL));
gcry_mpi_t outmpi = gcry_mpi_new(len * 8);
gcry_mpi_powm(outmpi, inmpi, key->d, key->n);
check(gcry_mpi_print(GCRYMPI_FMT_USG, out,len, NULL, outmpi));
return true;
}

40
src/rsa.h Normal file
View file

@ -0,0 +1,40 @@
/*
rsa.h -- RSA key handling
Copyright (C) 2007 Guus Sliepen <guus@tinc-vpn.org>
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., 675 Mass Ave, Cambridge, MA 02139, USA.
$Id$
*/
#ifndef __TINC_RSA_H__
#define __TINC_RSA_H__
#include <gcrypt.h>
typedef struct rsa_key_t {
gcry_mpi_t n;
gcry_mpi_t e;
gcry_mpi_t d;
} rsa_key_t;
extern bool read_pem_rsa_public_key(FILE *fp, struct rsa_key_t *key);
extern bool read_pem_rsa_private_key(FILE *fp, struct rsa_key_t *key);
extern unsigned int get_rsa_size(struct rsa_key_t *key);
extern bool rsa_public_encrypt(size_t len, void *in, void *out, struct rsa_key_t *key);
extern bool rsa_private_decrypt(size_t len, void *in, void *out, struct rsa_key_t *key);
#endif