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/*
* Dropbear - a SSH2 server
*
* Copyright (c) 2002,2003 Matt Johnston
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE. */
#include "includes.h"
#include "dbutil.h"
#include "signkey.h"
#include "buffer.h"
#include "ssh.h"
/* malloc a new sign_key and set the dss and rsa keys to NULL */
sign_key * new_sign_key() {
sign_key * ret;
ret = (sign_key*)m_malloc(sizeof(sign_key));
#ifdef DROPBEAR_DSS
ret->dsskey = NULL;
#endif
#ifdef DROPBEAR_RSA
ret->rsakey = NULL;
#endif
return ret;
}
/* Returns "ssh-dss" or "ssh-rsa" corresponding to the type. Exits fatally
* if the type is invalid */
const char* signkey_name_from_type(int type, int *namelen) {
#ifdef DROPBEAR_RSA
if (type == DROPBEAR_SIGNKEY_RSA) {
*namelen = SSH_SIGNKEY_RSA_LEN;
return SSH_SIGNKEY_RSA;
}
#endif
#ifdef DROPBEAR_DSS
if (type == DROPBEAR_SIGNKEY_DSS) {
*namelen = SSH_SIGNKEY_DSS_LEN;
return SSH_SIGNKEY_DSS;
}
#endif
dropbear_exit("bad key type %d", type);
return NULL; /* notreached */
}
/* Returns DROPBEAR_SIGNKEY_RSA, DROPBEAR_SIGNKEY_DSS,
* or DROPBEAR_SIGNKEY_NONE */
int signkey_type_from_name(const char* name, int namelen) {
#ifdef DROPBEAR_RSA
if (namelen == SSH_SIGNKEY_RSA_LEN
&& memcmp(name, SSH_SIGNKEY_RSA, SSH_SIGNKEY_RSA_LEN) == 0) {
return DROPBEAR_SIGNKEY_RSA;
}
#endif
#ifdef DROPBEAR_DSS
if (namelen == SSH_SIGNKEY_DSS_LEN
&& memcmp(name, SSH_SIGNKEY_DSS, SSH_SIGNKEY_DSS_LEN) == 0) {
return DROPBEAR_SIGNKEY_DSS;
}
#endif
return DROPBEAR_SIGNKEY_NONE;
}
/* returns DROPBEAR_SUCCESS on success, DROPBEAR_FAILURE on fail.
* type should be set by the caller to specify the type to read, and
* on return is set to the type read (useful when type = _ANY) */
int buf_get_pub_key(buffer *buf, sign_key *key, int *type) {
unsigned char* ident;
unsigned int len;
int keytype;
int ret = DROPBEAR_FAILURE;
TRACE(("enter buf_get_pub_key"))
ident = buf_getstring(buf, &len);
keytype = signkey_type_from_name(ident, len);
m_free(ident);
if (*type != DROPBEAR_SIGNKEY_ANY && *type != keytype) {
return DROPBEAR_FAILURE;
}
*type = keytype;
/* Rewind the buffer back before "ssh-rsa" etc */
buf_incrpos(buf, -len - 4);
#ifdef DROPBEAR_DSS
if (keytype == DROPBEAR_SIGNKEY_DSS) {
dss_key_free(key->dsskey);
key->dsskey = (dss_key*)m_malloc(sizeof(dss_key));
ret = buf_get_dss_pub_key(buf, key->dsskey);
if (ret == DROPBEAR_FAILURE) {
m_free(key->dsskey);
}
}
#endif
#ifdef DROPBEAR_RSA
if (keytype == DROPBEAR_SIGNKEY_RSA) {
rsa_key_free(key->rsakey);
key->rsakey = (rsa_key*)m_malloc(sizeof(rsa_key));
ret = buf_get_rsa_pub_key(buf, key->rsakey);
if (ret == DROPBEAR_FAILURE) {
m_free(key->rsakey);
}
}
#endif
TRACE(("leave buf_get_pub_key"))
return ret;
}
/* returns DROPBEAR_SUCCESS on success, DROPBEAR_FAILURE on fail.
* type should be set by the caller to specify the type to read, and
* on return is set to the type read (useful when type = _ANY) */
int buf_get_priv_key(buffer *buf, sign_key *key, int *type) {
unsigned char* ident;
unsigned int len;
int keytype;
int ret = DROPBEAR_FAILURE;
TRACE(("enter buf_get_priv_key"))
ident = buf_getstring(buf, &len);
keytype = signkey_type_from_name(ident, len);
m_free(ident);
if (*type != DROPBEAR_SIGNKEY_ANY && *type != keytype) {
TRACE(("wrong key type: %d %d", *type, keytype))
return DROPBEAR_FAILURE;
}
*type = keytype;
/* Rewind the buffer back before "ssh-rsa" etc */
buf_incrpos(buf, -len - 4);
#ifdef DROPBEAR_DSS
if (keytype == DROPBEAR_SIGNKEY_DSS) {
dss_key_free(key->dsskey);
key->dsskey = (dss_key*)m_malloc(sizeof(dss_key));
ret = buf_get_dss_priv_key(buf, key->dsskey);
if (ret == DROPBEAR_FAILURE) {
m_free(key->dsskey);
}
}
#endif
#ifdef DROPBEAR_RSA
if (keytype == DROPBEAR_SIGNKEY_RSA) {
rsa_key_free(key->rsakey);
key->rsakey = (rsa_key*)m_malloc(sizeof(rsa_key));
ret = buf_get_rsa_priv_key(buf, key->rsakey);
if (ret == DROPBEAR_FAILURE) {
m_free(key->rsakey);
}
}
#endif
TRACE(("leave buf_get_priv_key"))
return ret;
}
/* type is either DROPBEAR_SIGNKEY_DSS or DROPBEAR_SIGNKEY_RSA */
void buf_put_pub_key(buffer* buf, sign_key *key, int type) {
buffer *pubkeys;
TRACE(("enter buf_put_pub_key"))
pubkeys = buf_new(MAX_PUBKEY_SIZE);
#ifdef DROPBEAR_DSS
if (type == DROPBEAR_SIGNKEY_DSS) {
buf_put_dss_pub_key(pubkeys, key->dsskey);
}
#endif
#ifdef DROPBEAR_RSA
if (type == DROPBEAR_SIGNKEY_RSA) {
buf_put_rsa_pub_key(pubkeys, key->rsakey);
}
#endif
if (pubkeys->len == 0) {
dropbear_exit("bad key types in buf_put_pub_key");
}
buf_setpos(pubkeys, 0);
buf_putstring(buf, buf_getptr(pubkeys, pubkeys->len),
pubkeys->len);
buf_free(pubkeys);
TRACE(("leave buf_put_pub_key"))
}
/* type is either DROPBEAR_SIGNKEY_DSS or DROPBEAR_SIGNKEY_RSA */
void buf_put_priv_key(buffer* buf, sign_key *key, int type) {
TRACE(("enter buf_put_priv_key"))
TRACE(("type is %d", type))
#ifdef DROPBEAR_DSS
if (type == DROPBEAR_SIGNKEY_DSS) {
buf_put_dss_priv_key(buf, key->dsskey);
TRACE(("leave buf_put_priv_key: dss done"))
return;
}
#endif
#ifdef DROPBEAR_RSA
if (type == DROPBEAR_SIGNKEY_RSA) {
buf_put_rsa_priv_key(buf, key->rsakey);
TRACE(("leave buf_put_priv_key: rsa done"))
return;
}
#endif
dropbear_exit("bad key types in put pub key");
}
void sign_key_free(sign_key *key) {
TRACE(("enter sign_key_free"))
#ifdef DROPBEAR_DSS
dss_key_free(key->dsskey);
key->dsskey = NULL;
#endif
#ifdef DROPBEAR_RSA
rsa_key_free(key->rsakey);
key->rsakey = NULL;
#endif
m_free(key);
TRACE(("leave sign_key_free"))
}
static char hexdig(unsigned char x) {
if (x > 0xf)
return 'X';
if (x < 10)
return '0' + x;
else
return 'a' + x - 10;
}
/* Since we're not sure if we'll have md5 or sha1, we present both.
* MD5 is used in preference, but sha1 could still be useful */
#ifdef DROPBEAR_MD5_HMAC
static char * sign_key_md5_fingerprint(unsigned char* keyblob,
unsigned int keybloblen) {
char * ret;
hash_state hs;
unsigned char hash[MD5_HASH_SIZE];
unsigned int i;
unsigned int buflen;
md5_init(&hs);
/* skip the size int of the string - this is a bit messy */
md5_process(&hs, keyblob, keybloblen);
md5_done(&hs, hash);
/* "md5 hexfingerprinthere\0", each hex digit is "AB:" etc */
buflen = 4 + 3*MD5_HASH_SIZE;
ret = (char*)m_malloc(buflen);
memset(ret, 'Z', buflen);
strcpy(ret, "md5 ");
for (i = 0; i < MD5_HASH_SIZE; i++) {
unsigned int pos = 4 + i*3;
ret[pos] = hexdig(hash[i] >> 4);
ret[pos+1] = hexdig(hash[i] & 0x0f);
ret[pos+2] = ':';
}
ret[buflen-1] = 0x0;
return ret;
}
#else /* use SHA1 rather than MD5 for fingerprint */
static char * sign_key_sha1_fingerprint(unsigned char* keyblob,
unsigned int keybloblen) {
char * ret;
hash_state hs;
unsigned char hash[SHA1_HASH_SIZE];
unsigned int i;
unsigned int buflen;
sha1_init(&hs);
/* skip the size int of the string - this is a bit messy */
sha1_process(&hs, keyblob, keybloblen);
sha1_done(&hs, hash);
/* "sha1 hexfingerprinthere\0", each hex digit is "AB:" etc */
buflen = 5 + 3*SHA1_HASH_SIZE;
ret = (char*)m_malloc(buflen);
strcpy(ret, "sha1 ");
for (i = 0; i < SHA1_HASH_SIZE; i++) {
unsigned int pos = 5 + 3*i;
ret[pos] = hexdig(hash[i] >> 4);
ret[pos+1] = hexdig(hash[i] & 0x0f);
ret[pos+2] = ':';
}
ret[buflen-1] = 0x0;
return ret;
}
#endif /* MD5/SHA1 switch */
/* This will return a freshly malloced string, containing a fingerprint
* in either sha1 or md5 */
char * sign_key_fingerprint(unsigned char* keyblob, unsigned int keybloblen) {
#ifdef DROPBEAR_MD5_HMAC
return sign_key_md5_fingerprint(keyblob, keybloblen);
#else
return sign_key_sha1_fingerprint(keyblob, keybloblen);
#endif
}
void buf_put_sign(buffer* buf, sign_key *key, int type,
const unsigned char *data, unsigned int len) {
buffer *sigblob;
sigblob = buf_new(MAX_PUBKEY_SIZE);
#ifdef DROPBEAR_DSS
if (type == DROPBEAR_SIGNKEY_DSS) {
buf_put_dss_sign(sigblob, key->dsskey, data, len);
}
#endif
#ifdef DROPBEAR_RSA
if (type == DROPBEAR_SIGNKEY_RSA) {
buf_put_rsa_sign(sigblob, key->rsakey, data, len);
}
#endif
if (sigblob->len == 0) {
dropbear_exit("non-matching signing type");
}
buf_setpos(sigblob, 0);
buf_putstring(buf, buf_getptr(sigblob, sigblob->len),
sigblob->len);
buf_free(sigblob);
}
#ifdef DROPBEAR_SIGNKEY_VERIFY
/* Return DROPBEAR_SUCCESS or DROPBEAR_FAILURE.
* If FAILURE is returned, the position of
* buf is undefined. If SUCCESS is returned, buf will be positioned after the
* signature blob */
int buf_verify(buffer * buf, sign_key *key, const unsigned char *data,
unsigned int len) {
unsigned int bloblen;
unsigned char * ident = NULL;
unsigned int identlen = 0;
TRACE(("enter buf_verify"))
bloblen = buf_getint(buf);
ident = buf_getstring(buf, &identlen);
#ifdef DROPBEAR_DSS
if (bloblen == DSS_SIGNATURE_SIZE &&
memcmp(ident, SSH_SIGNKEY_DSS, identlen) == 0) {
m_free(ident);
if (key->dsskey == NULL) {
dropbear_exit("no dss key to verify signature");
}
return buf_dss_verify(buf, key->dsskey, data, len);
}
#endif
#ifdef DROPBEAR_RSA
if (memcmp(ident, SSH_SIGNKEY_RSA, identlen) == 0) {
m_free(ident);
if (key->rsakey == NULL) {
dropbear_exit("no rsa key to verify signature");
}
return buf_rsa_verify(buf, key->rsakey, data, len);
}
#endif
m_free(ident);
dropbear_exit("non-matching signing type");
return DROPBEAR_FAILURE;
}
#endif /* DROPBEAR_SIGNKEY_VERIFY */
#ifdef DROPBEAR_KEY_LINES /* ie we're using authorized_keys or known_hosts */
/* Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE when given a buffer containing
* a key, a key, and a type. The buffer is positioned at the start of the
* base64 data, and contains no trailing data */
/* If fingerprint is non-NULL, it will be set to a malloc()ed fingerprint
of the key if it is successfully decoded */
int cmp_base64_key(const unsigned char* keyblob, unsigned int keybloblen,
const unsigned char* algoname, unsigned int algolen,
buffer * line, char ** fingerprint) {
buffer * decodekey = NULL;
int ret = DROPBEAR_FAILURE;
unsigned int len, filealgolen;
unsigned long decodekeylen;
unsigned char* filealgo = NULL;
/* now we have the actual data */
len = line->len - line->pos;
decodekeylen = len * 2; /* big to be safe */
decodekey = buf_new(decodekeylen);
if (base64_decode(buf_getptr(line, len), len,
buf_getwriteptr(decodekey, decodekey->size),
&decodekeylen) != CRYPT_OK) {
TRACE(("checkpubkey: base64 decode failed"))
goto out;
}
TRACE(("checkpubkey: base64_decode success"))
buf_incrlen(decodekey, decodekeylen);
if (fingerprint) {
*fingerprint = sign_key_fingerprint(buf_getptr(decodekey, decodekeylen),
decodekeylen);
}
/* compare the keys */
if ( ( decodekeylen != keybloblen )
|| memcmp( buf_getptr(decodekey, decodekey->len),
keyblob, decodekey->len) != 0) {
TRACE(("checkpubkey: compare failed"))
goto out;
}
/* ... and also check that the algo specified and the algo in the key
* itself match */
filealgolen = buf_getint(decodekey);
filealgo = buf_getptr(decodekey, filealgolen);
if (filealgolen != algolen || memcmp(filealgo, algoname, algolen) != 0) {
TRACE(("checkpubkey: algo match failed"))
goto out;
}
/* All checks passed */
ret = DROPBEAR_SUCCESS;
out:
buf_free(decodekey);
decodekey = NULL;
return ret;
}
#endif