1 files changed, 484 insertions, 0 deletions
diff --git a/signkey.c b/signkey.c
new file mode 100644
index 0000000..b8afb58
--- /dev/null
+++ b/signkey.c
@@ -0,0 +1,484 @@
+/*
+ * 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 */
+int cmp_base64_key(const unsigned char* keyblob, unsigned int keybloblen, 
+					const unsigned char* algoname, unsigned int algolen, 
+					buffer * line) {
+
+	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);
+	
+	/* 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