X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/abc4e9a7a4e99c9e6addb1b63e655edcd1a7877f..HEAD:/ssh-rsa.c

diff --git a/ssh-rsa.c b/ssh-rsa.c
index 6fd47287..0e16ff85 100644
--- a/ssh-rsa.c
+++ b/ssh-rsa.c
@@ -1,51 +1,47 @@
+/* $OpenBSD: ssh-rsa.c,v 1.39 2006/08/03 03:34:42 deraadt Exp $ */
 /*
- * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
  *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: ssh-rsa.c,v 1.12 2001/11/07 22:10:28 markus Exp $");
+
+#include <sys/types.h>
 
 #include <openssl/evp.h>
 #include <openssl/err.h>
 
+#include <stdarg.h>
+#include <string.h>
+
 #include "xmalloc.h"
 #include "log.h"
 #include "buffer.h"
-#include "bufaux.h"
 #include "key.h"
-#include "ssh-rsa.h"
 #include "compat.h"
+#include "ssh.h"
+
+static int openssh_RSA_verify(int, u_char *, u_int, u_char *, u_int, RSA *);
 
 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
 int
-ssh_rsa_sign(
-    Key *key,
-    u_char **sigp, int *lenp,
-    u_char *data, int datalen)
+ssh_rsa_sign(const Key *key, u_char **sigp, u_int *lenp,
+    const u_char *data, u_int datalen)
 {
 	const EVP_MD *evp_md;
 	EVP_MD_CTX md;
-	u_char *digest, *sig, *ret;
+	u_char digest[EVP_MAX_MD_SIZE], *sig;
 	u_int slen, dlen, len;
 	int ok, nid;
 	Buffer b;
@@ -54,41 +50,36 @@ ssh_rsa_sign(
 		error("ssh_rsa_sign: no RSA key");
 		return -1;
 	}
-        if (datafellows & SSH_BUG_SIGBLOB) {
-		error("ssh_rsa_sign: SSH_BUG_SIGBLOB not supported");
-		return -1;
-	}
 	nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
 	if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
 		error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid);
 		return -1;
 	}
-	dlen = evp_md->md_size;
-	digest = xmalloc(dlen);
 	EVP_DigestInit(&md, evp_md);
 	EVP_DigestUpdate(&md, data, datalen);
-	EVP_DigestFinal(&md, digest, NULL);
+	EVP_DigestFinal(&md, digest, &dlen);
 
 	slen = RSA_size(key->rsa);
 	sig = xmalloc(slen);
 
 	ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
-	memset(digest, 'd', dlen);
-	xfree(digest);
+	memset(digest, 'd', sizeof(digest));
 
 	if (ok != 1) {
 		int ecode = ERR_get_error();
-		error("ssh_rsa_sign: RSA_sign failed: %s", ERR_error_string(ecode, NULL));
+
+		error("ssh_rsa_sign: RSA_sign failed: %s",
+		    ERR_error_string(ecode, NULL));
 		xfree(sig);
 		return -1;
 	}
 	if (len < slen) {
-		int diff = slen - len;
-		debug("slen %d > len %d", slen, len);
+		u_int diff = slen - len;
+		debug("slen %u > len %u", slen, len);
 		memmove(sig + diff, sig, len);
 		memset(sig, 0, diff);
 	} else if (len > slen) {
-		error("ssh_rsa_sign: slen %d slen2 %d", slen, len);
+		error("ssh_rsa_sign: slen %u slen2 %u", slen, len);
 		xfree(sig);
 		return -1;
 	}
@@ -97,44 +88,38 @@ ssh_rsa_sign(
 	buffer_put_cstring(&b, "ssh-rsa");
 	buffer_put_string(&b, sig, slen);
 	len = buffer_len(&b);
-	ret = xmalloc(len);
-	memcpy(ret, buffer_ptr(&b), len);
+	if (lenp != NULL)
+		*lenp = len;
+	if (sigp != NULL) {
+		*sigp = xmalloc(len);
+		memcpy(*sigp, buffer_ptr(&b), len);
+	}
 	buffer_free(&b);
 	memset(sig, 's', slen);
 	xfree(sig);
 
-	if (lenp != NULL)
-		*lenp = len;
-	if (sigp != NULL)
-		*sigp = ret;
 	return 0;
 }
 
 int
-ssh_rsa_verify(
-    Key *key,
-    u_char *signature, int signaturelen,
-    u_char *data, int datalen)
+ssh_rsa_verify(const Key *key, const u_char *signature, u_int signaturelen,
+    const u_char *data, u_int datalen)
 {
 	Buffer b;
 	const EVP_MD *evp_md;
 	EVP_MD_CTX md;
 	char *ktype;
-	u_char *sigblob, *digest;
-	u_int len, dlen;
+	u_char digest[EVP_MAX_MD_SIZE], *sigblob;
+	u_int len, dlen, modlen;
 	int rlen, ret, nid;
 
 	if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
 		error("ssh_rsa_verify: no RSA key");
 		return -1;
 	}
-        if (datafellows & SSH_BUG_SIGBLOB) {
-		error("ssh_rsa_verify: SSH_BUG_SIGBLOB not supported");
-		return -1;
-	}
-	if (BN_num_bits(key->rsa->n) < 768) {
-		error("ssh_rsa_verify: n too small: %d bits",
-		    BN_num_bits(key->rsa->n));
+	if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
+		error("ssh_rsa_verify: RSA modulus too small: %d < minimum %d bits",
+		    BN_num_bits(key->rsa->n), SSH_RSA_MINIMUM_MODULUS_SIZE);
 		return -1;
 	}
 	buffer_init(&b);
@@ -150,32 +135,129 @@ ssh_rsa_verify(
 	sigblob = buffer_get_string(&b, &len);
 	rlen = buffer_len(&b);
 	buffer_free(&b);
-	if(rlen != 0) {
+	if (rlen != 0) {
 		error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
 		xfree(sigblob);
 		return -1;
 	}
+	/* RSA_verify expects a signature of RSA_size */
+	modlen = RSA_size(key->rsa);
+	if (len > modlen) {
+		error("ssh_rsa_verify: len %u > modlen %u", len, modlen);
+		xfree(sigblob);
+		return -1;
+	} else if (len < modlen) {
+		u_int diff = modlen - len;
+		debug("ssh_rsa_verify: add padding: modlen %u > len %u",
+		    modlen, len);
+		sigblob = xrealloc(sigblob, 1, modlen);
+		memmove(sigblob + diff, sigblob, len);
+		memset(sigblob, 0, diff);
+		len = modlen;
+	}
 	nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
 	if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
 		error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
 		xfree(sigblob);
 		return -1;
 	}
-	dlen = evp_md->md_size;
-	digest = xmalloc(dlen);
 	EVP_DigestInit(&md, evp_md);
 	EVP_DigestUpdate(&md, data, datalen);
-	EVP_DigestFinal(&md, digest, NULL);
+	EVP_DigestFinal(&md, digest, &dlen);
 
-	ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
-	memset(digest, 'd', dlen);
-	xfree(digest);
+	ret = openssh_RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
+	memset(digest, 'd', sizeof(digest));
 	memset(sigblob, 's', len);
 	xfree(sigblob);
-	if (ret == 0) {
-		int ecode = ERR_get_error();
-		error("ssh_rsa_verify: RSA_verify failed: %s", ERR_error_string(ecode, NULL));
-	}
 	debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
 	return ret;
 }
+
+/*
+ * See:
+ * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/
+ * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn
+ */
+/*
+ * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
+ *	oiw(14) secsig(3) algorithms(2) 26 }
+ */
+static const u_char id_sha1[] = {
+	0x30, 0x21, /* type Sequence, length 0x21 (33) */
+	0x30, 0x09, /* type Sequence, length 0x09 */
+	0x06, 0x05, /* type OID, length 0x05 */
+	0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */
+	0x05, 0x00, /* NULL */
+	0x04, 0x14  /* Octet string, length 0x14 (20), followed by sha1 hash */
+};
+/*
+ * id-md5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
+ *	rsadsi(113549) digestAlgorithm(2) 5 }
+ */
+static const u_char id_md5[] = {
+	0x30, 0x20, /* type Sequence, length 0x20 (32) */
+	0x30, 0x0c, /* type Sequence, length 0x09 */
+	0x06, 0x08, /* type OID, length 0x05 */
+	0x2a, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, /* id-md5 */
+	0x05, 0x00, /* NULL */
+	0x04, 0x10  /* Octet string, length 0x10 (16), followed by md5 hash */
+};
+
+static int
+openssh_RSA_verify(int type, u_char *hash, u_int hashlen,
+    u_char *sigbuf, u_int siglen, RSA *rsa)
+{
+	u_int ret, rsasize, oidlen = 0, hlen = 0;
+	int len;
+	const u_char *oid = NULL;
+	u_char *decrypted = NULL;
+
+	ret = 0;
+	switch (type) {
+	case NID_sha1:
+		oid = id_sha1;
+		oidlen = sizeof(id_sha1);
+		hlen = 20;
+		break;
+	case NID_md5:
+		oid = id_md5;
+		oidlen = sizeof(id_md5);
+		hlen = 16;
+		break;
+	default:
+		goto done;
+	}
+	if (hashlen != hlen) {
+		error("bad hashlen");
+		goto done;
+	}
+	rsasize = RSA_size(rsa);
+	if (siglen == 0 || siglen > rsasize) {
+		error("bad siglen");
+		goto done;
+	}
+	decrypted = xmalloc(rsasize);
+	if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
+	    RSA_PKCS1_PADDING)) < 0) {
+		error("RSA_public_decrypt failed: %s",
+		    ERR_error_string(ERR_get_error(), NULL));
+		goto done;
+	}
+	if (len < 0 || (u_int)len != hlen + oidlen) {
+		error("bad decrypted len: %d != %d + %d", len, hlen, oidlen);
+		goto done;
+	}
+	if (memcmp(decrypted, oid, oidlen) != 0) {
+		error("oid mismatch");
+		goto done;
+	}
+	if (memcmp(decrypted + oidlen, hash, hlen) != 0) {
+		error("hash mismatch");
+		goto done;
+	}
+	ret = 1;
+done:
+	if (decrypted)
+		xfree(decrypted);
+	return ret;
+}