[tls] Use our own ASN.1 routines for certificate parsing

Use our own, more robust, ASN.1 parsing routines to extract the RSA
public key from a server certificate.  Remove the now-unused AXTLS
ASN.1 parser.

src/crypto/asn1.c

@@ -32,7 +32,7 @@
  *
  * @v cursor		ASN.1 object cursor
  * @v type		Expected type
- * @ret len		Length of object body, or -1 on error
+ * @ret len		Length of object body, or negative error
  *
  * The object cursor will be updated to point to the start of the
  * object body (i.e. the first byte following the length byte(s)), and
@@ -44,29 +44,32 @@
  * the cursor will be invalidated and a negative value will be
  * returned.
  */
-static int asn1_start_object ( struct asn1_cursor *cursor,
+static int asn1_start ( struct asn1_cursor *cursor,
 			       unsigned int type ) {
 	unsigned int len_len;
 	unsigned int len;
+	int rc;
 
 	/* Sanity check */
 	if ( cursor->len < 2 /* Tag byte and first length byte */ ) {
 		if ( cursor->len )
 			DBGC ( cursor, "ASN1 %p too short\n", cursor );
+		rc = -EINVAL;
 		goto notfound;
 	}
 
 	/* Check the tag byte */
-	if ( cursor->data[0] != type ) {
+	if ( *( ( uint8_t * ) cursor->data ) != type ) {
 		DBGC ( cursor, "ASN1 %p type mismatch (expected %d, got %d)\n",
-		       cursor, type, cursor->data[0] );
+		       cursor, type, *( ( uint8_t * ) cursor->data ) );
+		rc = -ENXIO;
 		goto notfound;
 	}
 	cursor->data++;
 	cursor->len--;
 
 	/* Extract length of the length field and sanity check */
-	len_len = cursor->data[0];
+	len_len = *( ( uint8_t * ) cursor->data );
 	if ( len_len & 0x80 ) {
 		len_len = ( len_len & 0x7f );
 		cursor->data++;
@@ -77,19 +80,21 @@ static int asn1_start_object ( struct asn1_cursor *cursor,
 	if ( cursor->len < len_len ) {
 		DBGC ( cursor, "ASN1 %p bad length field length %d (max "
 		       "%zd)\n", cursor, len_len, cursor->len );
+		rc = -EINVAL;
 		goto notfound;
 	}
 
 	/* Extract the length and sanity check */
 	for ( len = 0 ; len_len ; len_len-- ) {
 		len <<= 8;
-		len |= cursor->data[0];
+		len |= *( ( uint8_t * ) cursor->data );
 		cursor->data++;
 		cursor->len--;
 	}
 	if ( cursor->len < len ) {
 		DBGC ( cursor, "ASN1 %p bad length %d (max %zd)\n",
 		       cursor, len, cursor->len );
+		rc = -EINVAL;
 		goto notfound;
 	}
 
@@ -98,7 +103,7 @@ static int asn1_start_object ( struct asn1_cursor *cursor,
  notfound:
 	cursor->data = NULL;
 	cursor->len = 0;
-	return -1;
+	return rc;
 }
 
 /**
@@ -112,12 +117,12 @@ static int asn1_start_object ( struct asn1_cursor *cursor,
  * current ASN.1 object.  If any error occurs, the object cursor will
  * be invalidated.
  */
-int asn1_enter_object ( struct asn1_cursor *cursor, unsigned int type ) {
+int asn1_enter ( struct asn1_cursor *cursor, unsigned int type ) {
 	int len;
 
-	len = asn1_start_object ( cursor, type );
+	len = asn1_start ( cursor, type );
 	if ( len < 0 )
-		return -ENOENT;
+		return len;
 
 	cursor->len = len;
 	DBGC ( cursor, "ASN1 %p entered object type %02x (len %x)\n",
@@ -137,12 +142,12 @@ int asn1_enter_object ( struct asn1_cursor *cursor, unsigned int type ) {
  * object.  If any error occurs, the object cursor will be
  * invalidated.
  */
-int asn1_skip_object ( struct asn1_cursor *cursor, unsigned int type ) {
+int asn1_skip ( struct asn1_cursor *cursor, unsigned int type ) {
 	int len;
 
-	len = asn1_start_object ( cursor, type );
+	len = asn1_start ( cursor, type );
 	if ( len < 0 )
-		return -ENOENT;
+		return len;
 
 	cursor->data += len;
 	cursor->len -= len;

src/crypto/axtls/axtls_asn1.c

@@ -1,867 +0,0 @@
-/*
- *  Copyright(C) 2006 Cameron Rich
- *
- *  This library is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU Lesser General Public License as published by
- *  the Free Software Foundation; either version 2.1 of the License, or
- *  (at your option) any later version.
- *
- *  This library 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 Lesser General Public License for more details.
- *
- *  You should have received a copy of the GNU Lesser General Public License
- *  along with this library; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- */
-
-/**
- * @file asn1.c
- * 
- * Some primitive asn methods for extraction rsa modulus information. It also
- * is used for retrieving information from X.509 certificates.
- */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
-#include "crypto.h"
-
-#define SIG_OID_PREFIX_SIZE     8
-
-#define SIG_TYPE_MD2            0x02
-#define SIG_TYPE_MD5            0x04
-#define SIG_TYPE_SHA1           0x05
-
-/* Must be an RSA algorithm with either SHA1 or MD5 for verifying to work */
-static const uint8_t sig_oid_prefix[SIG_OID_PREFIX_SIZE] = 
-{
-    0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01
-};
-
-/* CN, O, OU */
-static const uint8_t g_dn_types[] = { 3, 10, 11 };
-
-static int get_asn1_length(const uint8_t *buf, int *offset)
-{
-    int len, i;
-
-    if (!(buf[*offset] & 0x80)) /* short form */
-    {
-        len = buf[(*offset)++];
-    }
-    else    /* long form */
-    {
-        int length_bytes = buf[(*offset)++]&0x7f;
-        len = 0;
-        for (i = 0; i < length_bytes; i++)
-        {
-            len <<= 8;
-            len += buf[(*offset)++];
-        }
-    }
-
-    return len;
-}
-
-/**
- * Skip the ASN1.1 object type and its length. Get ready to read the object's
- * data.
- */
-int asn1_next_obj(const uint8_t *buf, int *offset, int obj_type)
-{
-    if (buf[*offset] != obj_type)
-        return X509_NOT_OK;
-    (*offset)++;
-    return get_asn1_length(buf, offset);
-}
-
-/**
- * Skip over an ASN.1 object type completely. Get ready to read the next
- * object.
- */
-int asn1_skip_obj(const uint8_t *buf, int *offset, int obj_type)
-{
-    int len;
-
-    if (buf[*offset] != obj_type)
-        return X509_NOT_OK;
-    (*offset)++;
-    len = get_asn1_length(buf, offset);
-    *offset += len;
-    return 0;
-}
-
-/**
- * Read an integer value for ASN.1 data
- * Note: This function allocates memory which must be freed by the user.
- */
-int asn1_get_int(const uint8_t *buf, int *offset, uint8_t **object)
-{
-    int len;
-
-    if ((len = asn1_next_obj(buf, offset, ASN1_INTEGER)) < 0)
-        goto end_int_array;
-
-    *object = (uint8_t *)malloc(len);
-    memcpy(*object, &buf[*offset], len);
-    *offset += len;
-
-end_int_array:
-    return len;
-}
-
-#if 0
-
-/**
- * Get all the RSA private key specifics from an ASN.1 encoded file 
- */
-int asn1_get_private_key(const uint8_t *buf, int len, RSA_CTX **rsa_ctx)
-{
-    int offset = 7;
-    uint8_t *modulus, *priv_exp, *pub_exp;
-    int mod_len, priv_len, pub_len;
-#ifdef CONFIG_BIGINT_CRT
-    uint8_t *p, *q, *dP, *dQ, *qInv;
-    int p_len, q_len, dP_len, dQ_len, qInv_len;
-#endif
-
-    /* not in der format */
-    if (buf[0] != ASN1_SEQUENCE) /* basic sanity check */
-    {
-#ifdef CONFIG_SSL_FULL_MODE
-        printf("Error: This is not a valid ASN.1 file\n");
-#endif
-        return X509_INVALID_PRIV_KEY;
-    }
-
-    /* initialise the RNG */
-    RNG_initialize(buf, len);
-
-    mod_len = asn1_get_int(buf, &offset, &modulus);
-    pub_len = asn1_get_int(buf, &offset, &pub_exp);
-    priv_len = asn1_get_int(buf, &offset, &priv_exp);
-
-    if (mod_len <= 0 || pub_len <= 0 || priv_len <= 0)
-        return X509_INVALID_PRIV_KEY;
-
-#ifdef CONFIG_BIGINT_CRT
-    p_len = asn1_get_int(buf, &offset, &p);
-    q_len = asn1_get_int(buf, &offset, &q);
-    dP_len = asn1_get_int(buf, &offset, &dP);
-    dQ_len = asn1_get_int(buf, &offset, &dQ);
-    qInv_len = asn1_get_int(buf, &offset, &qInv);
-
-    if (p_len <= 0 || q_len <= 0 || dP_len <= 0 || dQ_len <= 0 || qInv_len <= 0)
-        return X509_INVALID_PRIV_KEY;
-
-    RSA_priv_key_new(rsa_ctx, 
-            modulus, mod_len, pub_exp, pub_len, priv_exp, priv_len,
-            p, p_len, q, p_len, dP, dP_len, dQ, dQ_len, qInv, qInv_len);
-
-    free(p);
-    free(q);
-    free(dP);
-    free(dQ);
-    free(qInv);
-#else
-    RSA_priv_key_new(rsa_ctx, 
-            modulus, mod_len, pub_exp, pub_len, priv_exp, priv_len);
-#endif
-
-    free(modulus);
-    free(priv_exp);
-    free(pub_exp);
-    return X509_OK;
-}
-
-/**
- * Get the time of a certificate. Ignore hours/minutes/seconds.
- */
-static int asn1_get_utc_time(const uint8_t *buf, int *offset, time_t *t)
-{
-    int ret = X509_NOT_OK, len, t_offset;
-    struct tm tm;
-
-    if (buf[(*offset)++] != ASN1_UTC_TIME)
-        goto end_utc_time;
-    len = get_asn1_length(buf, offset);
-    t_offset = *offset;
-
-    memset(&tm, 0, sizeof(struct tm));
-    tm.tm_year = (buf[t_offset] - '0')*10 + (buf[t_offset+1] - '0');
-
-    if (tm.tm_year <= 50)    /* 1951-2050 thing */
-    {
-        tm.tm_year += 100;
-    }
-
-    tm.tm_mon = (buf[t_offset+2] - '0')*10 + (buf[t_offset+3] - '0') - 1;
-    tm.tm_mday = (buf[t_offset+4] - '0')*10 + (buf[t_offset+5] - '0');
-    *t = mktime(&tm);
-    *offset += len;
-    ret = X509_OK;
-
-end_utc_time:
-    return ret;
-}
-
-/**
- * Get the version type of a certificate (which we don't actually care about)
- */
-static int asn1_version(const uint8_t *cert, int *offset, X509_CTX *x509_ctx)
-{
-    int ret = X509_NOT_OK;
-
-    (*offset) += 2;        /* get past explicit tag */
-    if (asn1_skip_obj(cert, offset, ASN1_INTEGER))
-        goto end_version;
-
-    ret = X509_OK;
-end_version:
-    return ret;
-}
-
-/**
- * Retrieve the notbefore and notafter certificate times.
- */
-static int asn1_validity(const uint8_t *cert, int *offset, X509_CTX *x509_ctx)
-{
-    return (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0 ||
-              asn1_get_utc_time(cert, offset, &x509_ctx->not_before) ||
-              asn1_get_utc_time(cert, offset, &x509_ctx->not_after));
-}
-
-/**
- * Get the components of a distinguished name 
- */
-static int asn1_get_oid_x520(const uint8_t *buf, int *offset)
-{
-    int dn_type = 0;
-    int len;
-
-    if ((len = asn1_next_obj(buf, offset, ASN1_OID)) < 0)
-        goto end_oid;
-
-    /* expect a sequence of 2.5.4.[x] where x is a one of distinguished name 
-       components we are interested in. */
-    if (len == 3 && buf[(*offset)++] == 0x55 && buf[(*offset)++] == 0x04)
-        dn_type = buf[(*offset)++];
-    else
-    {
-        *offset += len;     /* skip over it */
-    }
-
-end_oid:
-    return dn_type;
-}
-
-/**
- * Obtain an ASN.1 printable string type.
- */
-static int asn1_get_printable_str(const uint8_t *buf, int *offset, char **str)
-{
-    int len = X509_NOT_OK;
-
-    /* some certs have this awful crud in them for some reason */
-    if (buf[*offset] != ASN1_PRINTABLE_STR && 
-            buf[*offset] != ASN1_TELETEX_STR && buf[*offset] != ASN1_IA5_STR)
-        goto end_pnt_str;
-
-    (*offset)++;
-    len = get_asn1_length(buf, offset);
-    *str = (char *)malloc(len+1);       /* allow for null */
-    memcpy(*str, &buf[*offset], len);
-    (*str)[len] = 0;                    /* null terminate */
-    *offset += len;
-end_pnt_str:
-    return len;
-}
-
-/**
- * Get the subject name (or the issuer) of a certificate.
- */
-static int asn1_name(const uint8_t *cert, int *offset, char *dn[])
-{
-    int ret = X509_NOT_OK;
-    int dn_type;
-    char *tmp = NULL;
-
-    if (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0)
-        goto end_name;
-
-    while (asn1_next_obj(cert, offset, ASN1_SET) >= 0)
-    {
-        int i, found = 0;
-
-        if (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0 ||
-               (dn_type = asn1_get_oid_x520(cert, offset)) < 0)
-            goto end_name;
-
-        if (asn1_get_printable_str(cert, offset, &tmp) < 0)
-        {
-            free(tmp);
-            goto end_name;
-        }
-
-        /* find the distinguished named type */
-        for (i = 0; i < X509_NUM_DN_TYPES; i++)
-        {
-            if (dn_type == g_dn_types[i])
-            {
-                if (dn[i] == NULL)
-                {
-                    dn[i] = tmp;
-                    found = 1;
-                    break;
-                }
-            }
-        }
-
-        if (found == 0) /* not found so get rid of it */
-        {
-            free(tmp);
-        }
-    }
-
-    ret = X509_OK;
-end_name:
-    return ret;
-}
-
-/**
- * Read the modulus and public exponent of a certificate.
- */
-static int asn1_public_key(const uint8_t *cert, int *offset, X509_CTX *x509_ctx)
-{
-    int ret = X509_NOT_OK, mod_len, pub_len;
-    uint8_t *modulus, *pub_exp;
-
-    if (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0 ||
-            asn1_skip_obj(cert, offset, ASN1_SEQUENCE) ||
-            asn1_next_obj(cert, offset, ASN1_BIT_STRING) < 0)
-        goto end_pub_key;
-
-    (*offset)++;
-
-    if (asn1_next_obj(cert, offset, ASN1_SEQUENCE) < 0)
-        goto end_pub_key;
-
-    mod_len = asn1_get_int(cert, offset, &modulus);
-    pub_len = asn1_get_int(cert, offset, &pub_exp);
-
-    RSA_pub_key_new(&x509_ctx->rsa_ctx, modulus, mod_len, pub_exp, pub_len);
-
-    free(modulus);
-    free(pub_exp);
-    ret = X509_OK;
-
-end_pub_key:
-    return ret;
-}
-
-#ifdef CONFIG_SSL_CERT_VERIFICATION
-/**
- * Read the signature of the certificate.
- */
-static int asn1_signature(const uint8_t *cert, int *offset, X509_CTX *x509_ctx)
-{
-    int ret = X509_NOT_OK;
-
-    if (cert[(*offset)++] != ASN1_BIT_STRING)
-        goto end_sig;
-
-    x509_ctx->sig_len = get_asn1_length(cert, offset);
-    x509_ctx->signature = (uint8_t *)malloc(x509_ctx->sig_len);
-    memcpy(x509_ctx->signature, &cert[*offset], x509_ctx->sig_len);
-    *offset += x509_ctx->sig_len;
-    ret = X509_OK;
-
-end_sig:
-    return ret;
-}
-
-/*
- * Compare 2 distinguished name components for equality 
- * @return 0 if a match
- */
-static int asn1_compare_dn_comp(const char *dn1, const char *dn2)
-{
-    int ret = 1;
-
-    if ((dn1 && dn2 == NULL) || (dn1 == NULL && dn2)) goto err_no_match;
-
-    ret = (dn1 && dn2) ? strcmp(dn1, dn2) : 0;
-
-err_no_match:
-    return ret;
-}
-
-/**
- * Clean up all of the CA certificates.
- */
-void remove_ca_certs(CA_CERT_CTX *ca_cert_ctx)
-{
-    int i = 0;
-
-    while (i < CONFIG_X509_MAX_CA_CERTS && ca_cert_ctx->cert[i])
-    {
-        x509_free(ca_cert_ctx->cert[i]);
-        ca_cert_ctx->cert[i++] = NULL;
-    }
-
-    free(ca_cert_ctx);
-}
-
-/*
- * Compare 2 distinguished names for equality 
- * @return 0 if a match
- */
-static int asn1_compare_dn(char * const dn1[], char * const dn2[])
-{
-    int i;
-
-    for (i = 0; i < X509_NUM_DN_TYPES; i++)
-    {
-        if (asn1_compare_dn_comp(dn1[i], dn2[i]))
-        {
-            return 1;
-        }
-    }
-
-    return 0;       /* all good */
-}
-
-/**
- * Retrieve the signature from a certificate.
- */
-const uint8_t *x509_get_signature(const uint8_t *asn1_sig, int *len)
-{
-    int offset = 0;
-    const uint8_t *ptr = NULL;
-
-    if (asn1_next_obj(asn1_sig, &offset, ASN1_SEQUENCE) < 0 || 
-            asn1_skip_obj(asn1_sig, &offset, ASN1_SEQUENCE))
-        goto end_get_sig;
-
-    if (asn1_sig[offset++] != ASN1_OCTET_STRING)
-        goto end_get_sig;
-    *len = get_asn1_length(asn1_sig, &offset);
-    ptr = &asn1_sig[offset];          /* all ok */
-
-end_get_sig:
-    return ptr;
-}
-
-#endif
-
-/**
- * Read the signature type of the certificate. We only support RSA-MD5 and
- * RSA-SHA1 signature types.
- */
-static int asn1_signature_type(const uint8_t *cert, 
-                                int *offset, X509_CTX *x509_ctx)
-{
-    int ret = X509_NOT_OK, len;
-
-    if (cert[(*offset)++] != ASN1_OID)
-        goto end_check_sig;
-
-    len = get_asn1_length(cert, offset);
-
-    if (memcmp(sig_oid_prefix, &cert[*offset], SIG_OID_PREFIX_SIZE))
-        goto end_check_sig;     /* unrecognised cert type */
-
-    x509_ctx->sig_type = cert[*offset + SIG_OID_PREFIX_SIZE];
-
-    *offset += len;
-    if (asn1_skip_obj(cert, offset, ASN1_NULL))
-        goto end_check_sig;
-    ret = X509_OK;
-
-end_check_sig:
-    return ret;
-}
-
-/**
- * Construct a new x509 object.
- * @return 0 if ok. < 0 if there was a problem.
- */
-int x509_new(const uint8_t *cert, int *len, X509_CTX **ctx)
-{
-    int begin_tbs, end_tbs;
-    int ret = X509_NOT_OK, offset = 0, cert_size = 0;
-    X509_CTX *x509_ctx;
-    BI_CTX *bi_ctx;
-
-    *ctx = (X509_CTX *)calloc(1, sizeof(X509_CTX));
-    x509_ctx = *ctx;
-
-    /* get the certificate size */
-    asn1_skip_obj(cert, &cert_size, ASN1_SEQUENCE); 
-
-    if (asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0)
-        goto end_cert;
-
-    begin_tbs = offset;         /* start of the tbs */
-    end_tbs = begin_tbs;        /* work out the end of the tbs */
-    asn1_skip_obj(cert, &end_tbs, ASN1_SEQUENCE);
-
-    if (asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0)
-        goto end_cert;
-
-    if (cert[offset] == ASN1_EXPLICIT_TAG)   /* optional version */
-    {
-        if (asn1_version(cert, &offset, x509_ctx))
-            goto end_cert;
-    }
-
-    if (asn1_skip_obj(cert, &offset, ASN1_INTEGER) || /* serial number */ 
-            asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0)
-        goto end_cert;
-
-    /* make sure the signature is ok */
-    if (asn1_signature_type(cert, &offset, x509_ctx))
-    {
-        ret = X509_VFY_ERROR_UNSUPPORTED_DIGEST;
-        goto end_cert;
-    }
-
-    if (asn1_name(cert, &offset, x509_ctx->ca_cert_dn) || 
-            asn1_validity(cert, &offset, x509_ctx) ||
-            asn1_name(cert, &offset, x509_ctx->cert_dn) ||
-            asn1_public_key(cert, &offset, x509_ctx))
-        goto end_cert;
-
-    bi_ctx = x509_ctx->rsa_ctx->bi_ctx;
-
-#ifdef CONFIG_SSL_CERT_VERIFICATION /* only care if doing verification */
-    /* use the appropriate signature algorithm (either SHA1 or MD5) */
-    if (x509_ctx->sig_type == SIG_TYPE_MD5)
-    {
-        MD5_CTX md5_ctx;
-        uint8_t md5_dgst[MD5_SIZE];
-        MD5Init(&md5_ctx);
-        MD5Update(&md5_ctx, &cert[begin_tbs], end_tbs-begin_tbs);
-        MD5Final(&md5_ctx, md5_dgst);
-        x509_ctx->digest = bi_import(bi_ctx, md5_dgst, MD5_SIZE);
-    }
-    else if (x509_ctx->sig_type == SIG_TYPE_SHA1)
-    {
-        SHA1_CTX sha_ctx;
-        uint8_t sha_dgst[SHA1_SIZE];
-        SHA1Init(&sha_ctx);
-        SHA1Update(&sha_ctx, &cert[begin_tbs], end_tbs-begin_tbs);
-        SHA1Final(&sha_ctx, sha_dgst);
-        x509_ctx->digest = bi_import(bi_ctx, sha_dgst, SHA1_SIZE);
-    }
-
-    offset = end_tbs;   /* skip the v3 data */
-    if (asn1_skip_obj(cert, &offset, ASN1_SEQUENCE) || 
-            asn1_signature(cert, &offset, x509_ctx))
-        goto end_cert;
-#endif
-
-    if (len)
-    {
-        *len = cert_size;
-    }
-
-    ret = X509_OK;
-end_cert:
-
-#ifdef CONFIG_SSL_FULL_MODE
-    if (ret)
-    {
-        printf("Error: Invalid X509 ASN.1 file\n");
-    }
-#endif
-
-    return ret;
-}
-
-/**
- * Free an X.509 object's resources.
- */
-void x509_free(X509_CTX *x509_ctx)
-{
-    X509_CTX *next;
-    int i;
-
-    if (x509_ctx == NULL)       /* if already null, then don't bother */
-        return;
-
-    for (i = 0; i < X509_NUM_DN_TYPES; i++)
-    {
-        free(x509_ctx->ca_cert_dn[i]);
-        free(x509_ctx->cert_dn[i]);
-    }
-
-    free(x509_ctx->signature);
-
-#ifdef CONFIG_SSL_CERT_VERIFICATION 
-    if (x509_ctx->digest)
-    {
-        bi_free(x509_ctx->rsa_ctx->bi_ctx, x509_ctx->digest);
-    }
-#endif
-
-    RSA_free(x509_ctx->rsa_ctx);
-
-    next = x509_ctx->next;
-    free(x509_ctx);
-    x509_free(next);        /* clear the chain */
-}
-
-#ifdef CONFIG_SSL_CERT_VERIFICATION
-/**
- * Do some basic checks on the certificate chain.
- *
- * Certificate verification consists of a number of checks:
- * - A root certificate exists in the certificate store.
- * - The date of the certificate is after the start date.
- * - The date of the certificate is before the finish date.
- * - The certificate chain is valid.
- * - That the certificate(s) are not self-signed.
- * - The signature of the certificate is valid.
- */
-int x509_verify(const CA_CERT_CTX *ca_cert_ctx, const X509_CTX *cert) 
-{
-    int ret = X509_OK, i = 0;
-    bigint *cert_sig;
-    X509_CTX *next_cert = NULL;
-    BI_CTX *ctx;
-    bigint *mod, *expn;
-    struct timeval tv;
-    int match_ca_cert = 0;
-
-    if (cert == NULL || ca_cert_ctx == NULL)
-    {
-        ret = X509_VFY_ERROR_NO_TRUSTED_CERT;       
-        goto end_verify;
-    }
-
-    /* last cert in the chain - look for a trusted cert */
-    if (cert->next == NULL)
-    {
-        while (i < CONFIG_X509_MAX_CA_CERTS && ca_cert_ctx->cert[i])
-        {
-            if (asn1_compare_dn(cert->ca_cert_dn,
-                                        ca_cert_ctx->cert[i]->cert_dn) == 0)
-            {
-                match_ca_cert = 1;
-                break;
-            }
-
-            i++;
-        }
-
-        if (i < CONFIG_X509_MAX_CA_CERTS && ca_cert_ctx->cert[i])
-        {
-            next_cert = ca_cert_ctx->cert[i];
-        }
-        else    /* trusted cert not found */
-        {
-            ret = X509_VFY_ERROR_NO_TRUSTED_CERT;       
-            goto end_verify;
-        }
-    }
-    else
-    {
-        next_cert = cert->next;
-    }
-
-    gettimeofday(&tv, NULL);
-
-    /* check the not before date */
-    if (tv.tv_sec < cert->not_before)
-    {
-        ret = X509_VFY_ERROR_NOT_YET_VALID;
-        goto end_verify;
-    }
-
-    /* check the not after date */
-    if (tv.tv_sec > cert->not_after)
-    {
-        ret = X509_VFY_ERROR_EXPIRED;
-        goto end_verify;
-    }
-
-    /* check the chain integrity */
-    if (asn1_compare_dn(cert->ca_cert_dn, next_cert->cert_dn))
-    {
-        ret = X509_VFY_ERROR_INVALID_CHAIN;
-        goto end_verify;
-    }
-
-    /* check for self-signing */
-    if (!match_ca_cert && asn1_compare_dn(cert->ca_cert_dn, cert->cert_dn) == 0)
-    {
-        ret = X509_VFY_ERROR_SELF_SIGNED;
-        goto end_verify;
-    }
-
-    /* check the signature */
-    ctx = cert->rsa_ctx->bi_ctx;
-    mod = next_cert->rsa_ctx->m;
-    expn = next_cert->rsa_ctx->e;
-    cert_sig = RSA_sign_verify(ctx, cert->signature, cert->sig_len, 
-            bi_clone(ctx, mod), bi_clone(ctx, expn));
-
-    if (cert_sig)
-    {
-        ret = cert->digest ?    /* check the signature */
-            bi_compare(cert_sig, cert->digest) :
-            X509_VFY_ERROR_UNSUPPORTED_DIGEST;
-        bi_free(ctx, cert_sig);
-
-        if (ret)
-            goto end_verify;
-    }
-    else
-    {
-        ret = X509_VFY_ERROR_BAD_SIGNATURE;
-        goto end_verify;
-    }
-
-    /* go down the certificate chain using recursion. */
-    if (ret == 0 && cert->next)
-    {
-        ret = x509_verify(ca_cert_ctx, next_cert);
-    }
-
-end_verify:
-    return ret;
-}
-#endif
-
-#if defined (CONFIG_SSL_FULL_MODE)
-/**
- * Used for diagnostics.
- */
-void x509_print(CA_CERT_CTX *ca_cert_ctx, const X509_CTX *cert) 
-{
-    if (cert == NULL)
-        return;
-
-    printf("----------------   CERT DEBUG   ----------------\n");
-    printf("* CA Cert Distinguished Name\n");
-    if (cert->ca_cert_dn[X509_COMMON_NAME])
-    {
-        printf("Common Name (CN):\t%s\n", cert->ca_cert_dn[X509_COMMON_NAME]);
-    }
-
-    if (cert->ca_cert_dn[X509_ORGANIZATION])
-    {
-        printf("Organization (O):\t%s\n", cert->ca_cert_dn[X509_ORGANIZATION]);
-    }
-
-    if (cert->ca_cert_dn[X509_ORGANIZATIONAL_TYPE])
-    {
-        printf("Organizational Unit (OU): %s\n", 
-                cert->ca_cert_dn[X509_ORGANIZATIONAL_TYPE]);
-    }
-
-    printf("* Cert Distinguished Name\n");
-    if (cert->cert_dn[X509_COMMON_NAME])
-    {
-        printf("Common Name (CN):\t%s\n", cert->cert_dn[X509_COMMON_NAME]);
-    }
-
-    if (cert->cert_dn[X509_ORGANIZATION])
-    {
-        printf("Organization (O):\t%s\n", cert->cert_dn[X509_ORGANIZATION]);
-    }
-
-    if (cert->cert_dn[X509_ORGANIZATIONAL_TYPE])
-    {
-        printf("Organizational Unit (OU): %s\n", 
-                cert->cert_dn[X509_ORGANIZATIONAL_TYPE]);
-    }
-
-    printf("Not Before:\t\t%s", ctime(&cert->not_before));
-    printf("Not After:\t\t%s", ctime(&cert->not_after));
-    printf("RSA bitsize:\t\t%d\n", cert->rsa_ctx->num_octets*8);
-    printf("Sig Type:\t\t");
-    switch (cert->sig_type)
-    {
-        case SIG_TYPE_MD5:
-            printf("MD5\n");
-            break;
-        case SIG_TYPE_SHA1:
-            printf("SHA1\n");
-            break;
-        case SIG_TYPE_MD2:
-            printf("MD2\n");
-            break;
-        default:
-            printf("Unrecognized: %d\n", cert->sig_type);
-            break;
-    }
-
-    printf("Verify:\t\t\t");
-
-    if (ca_cert_ctx)
-    {
-        x509_display_error(x509_verify(ca_cert_ctx, cert));
-    }
-
-    printf("\n");
-#if 0
-    print_blob("Signature", cert->signature, cert->sig_len);
-    bi_print("Modulus", cert->rsa_ctx->m);
-    bi_print("Pub Exp", cert->rsa_ctx->e);
-#endif
-
-    if (ca_cert_ctx)
-    {
-        x509_print(ca_cert_ctx, cert->next);
-    }
-}
-
-void x509_display_error(int error)
-{
-    switch (error)
-    {
-        case X509_NOT_OK:
-            printf("X509 not ok");
-            break;
-
-        case X509_VFY_ERROR_NO_TRUSTED_CERT:
-            printf("No trusted cert is available");
-            break;
-
-        case X509_VFY_ERROR_BAD_SIGNATURE:
-            printf("Bad signature");
-            break;
-
-        case X509_VFY_ERROR_NOT_YET_VALID:
-            printf("Cert is not yet valid");
-            break;
-
-        case X509_VFY_ERROR_EXPIRED:
-            printf("Cert has expired");
-            break;
-
-        case X509_VFY_ERROR_SELF_SIGNED:
-            printf("Cert is self-signed");
-            break;
-
-        case X509_VFY_ERROR_INVALID_CHAIN:
-            printf("Chain is invalid (check order of certs)");
-            break;
-
-        case X509_VFY_ERROR_UNSUPPORTED_DIGEST:
-            printf("Unsupported digest");
-            break;
-
-        case X509_INVALID_PRIV_KEY:
-            printf("Invalid private key");
-            break;
-    }
-}
-#endif      /* CONFIG_SSL_FULL_MODE */
-
-#endif

src/crypto/x509.c

@@ -0,0 +1,181 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * 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 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.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <gpxe/asn1.h>
+#include <gpxe/x509.h>
+
+/** @file
+ *
+ * X.509 certificates
+ *
+ * The structure of X.509v3 certificates is concisely documented in
+ * RFC5280 section 4.1.  The structure of RSA public keys is
+ * documented in RFC2313.
+ */
+
+/** Object Identifier for "rsaEncryption" (1.2.840.113549.1.1.1) */
+static const uint8_t oid_rsa_encryption[] = { 0x2a, 0x86, 0x48, 0x86, 0xf7,
+					      0x0d, 0x01, 0x01, 0x01 };
+
+/**
+ * Identify X.509 certificate public key
+ *
+ * @v certificate	Certificate
+ * @v algorithm		Public key algorithm to fill in
+ * @v pubkey		Public key value to fill in
+ * @ret rc		Return status code
+ */
+static int x509_public_key ( const struct asn1_cursor *certificate,
+			     struct asn1_cursor *algorithm,
+			     struct asn1_cursor *pubkey ) {
+	struct asn1_cursor cursor;
+	int rc;
+
+	/* Locate subjectPublicKeyInfo */
+	memcpy ( &cursor, certificate, sizeof ( cursor ) );
+	rc = ( asn1_enter ( &cursor, ASN1_SEQUENCE ), /* Certificate */
+	       asn1_enter ( &cursor, ASN1_SEQUENCE ), /* tbsCertificate */
+	       asn1_skip ( &cursor, ASN1_EXPLICIT_TAG ), /* version */
+	       asn1_skip ( &cursor, ASN1_INTEGER ), /* serialNumber */
+	       asn1_skip ( &cursor, ASN1_SEQUENCE ), /* signature */
+	       asn1_skip ( &cursor, ASN1_SEQUENCE ), /* issuer */
+	       asn1_skip ( &cursor, ASN1_SEQUENCE ), /* validity */
+	       asn1_skip ( &cursor, ASN1_SEQUENCE ), /* name */
+	       asn1_enter ( &cursor, ASN1_SEQUENCE )/* subjectPublicKeyInfo*/);
+	if ( rc != 0 ) {
+		DBG ( "Cannot locate subjectPublicKeyInfo in:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+		return rc;
+	}
+
+	/* Locate algorithm */
+	memcpy ( algorithm, &cursor, sizeof ( *algorithm ) );
+	rc = ( asn1_enter ( algorithm, ASN1_SEQUENCE ) /* algorithm */ );
+	if ( rc != 0 ) {
+		DBG ( "Cannot locate algorithm in:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+		return rc;
+	}
+
+	/* Locate subjectPublicKey */
+	memcpy ( pubkey, &cursor, sizeof ( *pubkey ) );
+	rc = ( asn1_skip ( pubkey, ASN1_SEQUENCE ), /* algorithm */
+	       asn1_enter ( pubkey, ASN1_BIT_STRING ) /* subjectPublicKey*/ );
+	if ( rc != 0 ) {
+		DBG ( "Cannot locate subjectPublicKey in:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Identify X.509 certificate RSA modulus and public exponent
+ *
+ * @v certificate	Certificate
+ * @v rsa		RSA public key to fill in
+ * @ret rc		Return status code
+ *
+ * The caller is responsible for eventually calling
+ * x509_free_rsa_public_key() to free the storage allocated to hold
+ * the RSA modulus and exponent.
+ */
+int x509_rsa_public_key ( const struct asn1_cursor *certificate,
+			  struct x509_rsa_public_key *rsa_pubkey ) {
+	struct asn1_cursor algorithm;
+	struct asn1_cursor pubkey;
+	struct asn1_cursor modulus;
+	struct asn1_cursor exponent;
+	int rc;
+
+	/* First, extract the public key algorithm and key data */
+	if ( ( rc = x509_public_key ( certificate, &algorithm,
+				      &pubkey ) ) != 0 )
+		return rc;
+
+	/* Check that algorithm is RSA */
+	rc = ( asn1_enter ( &algorithm, ASN1_OID ) /* algorithm */ );
+	if ( rc != 0 ) {
+		DBG ( "Cannot locate algorithm:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+	return rc;
+	}
+	if ( ( algorithm.len != sizeof ( oid_rsa_encryption ) ) ||
+	     ( memcmp ( algorithm.data, &oid_rsa_encryption,
+			sizeof ( oid_rsa_encryption ) ) != 0 ) ) {
+		DBG ( "algorithm is not rsaEncryption in:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+		return -ENOTSUP;
+	}
+
+	/* Check that public key is a byte string, i.e. that the
+	 * "unused bits" byte contains zero.
+	 */
+	if ( ( pubkey.len < 1 ) ||
+	     ( ( *( uint8_t * ) pubkey.data ) != 0 ) ) {
+		DBG ( "subjectPublicKey is not a byte string in:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+		return -ENOTSUP;
+	}
+	pubkey.data++;
+	pubkey.len--;
+
+	/* Pick out the modulus and exponent */
+	rc = ( asn1_enter ( &pubkey, ASN1_SEQUENCE ) /* RSAPublicKey */ );
+	if ( rc != 0 ) {
+		DBG ( "Cannot locate RSAPublicKey in:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+		return -ENOTSUP;
+	}
+	memcpy ( &modulus, &pubkey, sizeof ( modulus ) );
+	rc = ( asn1_enter ( &modulus, ASN1_INTEGER ) /* modulus */ );
+	if ( rc != 0 ) {
+		DBG ( "Cannot locate modulus in:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+		return -ENOTSUP;
+	}
+	memcpy ( &exponent, &pubkey, sizeof ( exponent ) );
+	rc = ( asn1_skip ( &exponent, ASN1_INTEGER ), /* modulus */
+	       asn1_enter ( &exponent, ASN1_INTEGER ) /* publicExponent */ );
+	if ( rc != 0 ) {
+		DBG ( "Cannot locate publicExponent in:\n" );
+		DBG_HDA ( 0, certificate->data, certificate->len );
+		return -ENOTSUP;
+	}
+
+	/* Allocate space and copy out modulus and exponent */
+	rsa_pubkey->modulus = malloc ( modulus.len + exponent.len );
+	if ( ! rsa_pubkey->modulus )
+		return -ENOMEM;
+	rsa_pubkey->exponent = ( rsa_pubkey->modulus + modulus.len );
+	memcpy ( rsa_pubkey->modulus, modulus.data, modulus.len );
+	rsa_pubkey->modulus_len = modulus.len;
+	memcpy ( rsa_pubkey->exponent, exponent.data, exponent.len );
+	rsa_pubkey->exponent_len = exponent.len;
+
+	DBG2 ( "RSA modulus:\n" );
+	DBG2_HDA ( 0, rsa_pubkey->modulus, rsa_pubkey->modulus_len );
+	DBG2 ( "RSA exponent:\n" );
+	DBG2_HDA ( 0, rsa_pubkey->exponent, rsa_pubkey->exponent_len );
+
+	return 0;
+}

src/include/gpxe/asn1.h

@@ -21,12 +21,12 @@
  */
 struct asn1_cursor {
 	/** Start of data */
-	uint8_t *data;
+	void *data;
 	/** Length of data */
 	size_t len;
 };
 
-extern int asn1_enter_object ( struct asn1_cursor *cursor, unsigned int type );
-extern int asn1_skip_object ( struct asn1_cursor *cursor, unsigned int type );
+extern int asn1_enter ( struct asn1_cursor *cursor, unsigned int type );
+extern int asn1_skip ( struct asn1_cursor *cursor, unsigned int type );
 
 #endif /* _GPXE_ASN1_H */

src/include/gpxe/errfile.h

@@ -168,6 +168,7 @@
 #define ERRFILE_smbios_settings	      ( ERRFILE_OTHER | 0x00130000 )
 #define ERRFILE_efi_smbios	      ( ERRFILE_OTHER | 0x00140000 )
 #define ERRFILE_pxemenu		      ( ERRFILE_OTHER | 0x00150000 )
+#define ERRFILE_x509		      ( ERRFILE_OTHER | 0x00160000 )
 
 /** @} */
 

src/include/gpxe/tls.h

@@ -14,6 +14,7 @@
 #include <gpxe/crypto.h>
 #include <gpxe/md5.h>
 #include <gpxe/sha1.h>
+#include <gpxe/x509.h>
 
 /** A TLS header */
 struct tls_header {
@@ -157,10 +158,7 @@ struct tls_session {
 	uint8_t handshake_sha1_ctx[SHA1_CTX_SIZE];
 
 	/** Hack: server RSA public key */
-	uint8_t *rsa_mod;
-	size_t rsa_mod_len;
-	uint8_t *rsa_pub_exp;
-	size_t rsa_pub_exp_len;
+	struct x509_rsa_public_key rsa;
 
 	/** TX sequence number */
 	uint64_t tx_seq;

src/include/gpxe/x509.h

@@ -0,0 +1,39 @@
+#ifndef _GPXE_X509_H
+#define _GPXE_X509_H
+
+/** @file
+ *
+ * X.509 certificates
+ *
+ */
+
+#include <stdint.h>
+
+struct asn1_cursor;
+
+/** An X.509 RSA public key */
+struct x509_rsa_public_key {
+	/** Modulus */
+	uint8_t *modulus;
+	/** Modulus length */
+	size_t modulus_len;
+	/** Exponent */
+	uint8_t *exponent;
+	/** Exponent length */
+	size_t exponent_len;
+};
+
+/**
+ * Free X.509 RSA public key
+ *
+ * @v rsa_pubkey	RSA public key
+ */
+static inline void
+x509_free_rsa_public_key ( struct x509_rsa_public_key *rsa_pubkey ) {
+	free ( rsa_pubkey->modulus );
+}
+
+extern int x509_rsa_public_key ( const struct asn1_cursor *certificate,
+				 struct x509_rsa_public_key *rsa_pubkey );
+
+#endif /* _GPXE_X509_H */

src/net/tls.c

@@ -36,6 +36,8 @@
 #include <gpxe/xfer.h>
 #include <gpxe/open.h>
 #include <gpxe/filter.h>
+#include <gpxe/asn1.h>
+#include <gpxe/x509.h>
 #include <gpxe/tls.h>
 
 static int tls_send_plaintext ( struct tls_session *tls, unsigned int type,
@@ -43,6 +45,33 @@ static int tls_send_plaintext ( struct tls_session *tls, unsigned int type,
 static void tls_clear_cipher ( struct tls_session *tls,
 			       struct tls_cipherspec *cipherspec );
 
+/******************************************************************************
+ *
+ * Utility functions
+ *
+ ******************************************************************************
+ */
+
+/**
+ * Extract 24-bit field value
+ *
+ * @v field24		24-bit field
+ * @ret value		Field value
+ *
+ * TLS uses 24-bit integers in several places, which are awkward to
+ * parse in C.
+ */
+static unsigned long tls_uint24 ( uint8_t field24[3] ) {
+	return ( ( field24[0] << 16 ) + ( field24[1] << 8 ) + field24[2] );
+}
+
+/******************************************************************************
+ *
+ * Cleanup functions
+ *
+ ******************************************************************************
+ */
+
 /**
  * Free TLS session
  *
@@ -57,8 +86,7 @@ static void free_tls ( struct refcnt *refcnt ) {
 	tls_clear_cipher ( tls, &tls->tx_cipherspec_pending );
 	tls_clear_cipher ( tls, &tls->rx_cipherspec );
 	tls_clear_cipher ( tls, &tls->rx_cipherspec_pending );
-	free ( tls->rsa_mod );
-	free ( tls->rsa_pub_exp );
+	x509_free_rsa_public_key ( &tls->rsa );
 	free ( tls->rx_data );
 
 	/* Free TLS structure itself */
@@ -622,8 +650,8 @@ static int tls_send_client_hello ( struct tls_session *tls ) {
 static int tls_send_client_key_exchange ( struct tls_session *tls ) {
 	/* FIXME: Hack alert */
 	RSA_CTX *rsa_ctx;
-	RSA_pub_key_new ( &rsa_ctx, tls->rsa_mod, tls->rsa_mod_len,
-			  tls->rsa_pub_exp, tls->rsa_pub_exp_len );
+	RSA_pub_key_new ( &rsa_ctx, tls->rsa.modulus, tls->rsa.modulus_len,
+			  tls->rsa.exponent, tls->rsa.exponent_len );
 	struct {
 		uint32_t type_length;
 		uint16_t encrypted_pre_master_secret_len;
@@ -641,8 +669,8 @@ static int tls_send_client_key_exchange ( struct tls_session *tls ) {
 	DBGC ( tls, "RSA encrypting plaintext, modulus, exponent:\n" );
 	DBGC_HD ( tls, &tls->pre_master_secret,
 		  sizeof ( tls->pre_master_secret ) );
-	DBGC_HD ( tls, tls->rsa_mod, tls->rsa_mod_len );
-	DBGC_HD ( tls, tls->rsa_pub_exp, tls->rsa_pub_exp_len );
+	DBGC_HD ( tls, tls->rsa.modulus, tls->rsa.modulus_len );
+	DBGC_HD ( tls, tls->rsa.exponent, tls->rsa.exponent_len );
 	RSA_encrypt ( rsa_ctx, ( const uint8_t * ) &tls->pre_master_secret,
 		      sizeof ( tls->pre_master_secret ),
 		      key_xchg.encrypted_pre_master_secret, 0 );
@@ -761,17 +789,16 @@ static int tls_new_alert ( struct tls_session *tls, void *data, size_t len ) {
 }
 
 /**
- * Receive new Server Hello record
+ * Receive new Server Hello handshake record
  *
  * @v tls		TLS session
- * @v data		Plaintext record
- * @v len		Length of plaintext record
+ * @v data		Plaintext handshake record
+ * @v len		Length of plaintext handshake record
  * @ret rc		Return status code
  */
 static int tls_new_server_hello ( struct tls_session *tls,
 				  void *data, size_t len ) {
 	struct {
-		uint32_t type_length;
 		uint16_t version;
 		uint8_t random[32];
 		uint8_t session_id_len;
@@ -818,72 +845,74 @@ static int tls_new_server_hello ( struct tls_session *tls,
 }
 
 /**
- * Receive new Certificate record
+ * Receive new Certificate handshake record
  *
  * @v tls		TLS session
- * @v data		Plaintext record
- * @v len		Length of plaintext record
+ * @v data		Plaintext handshake record
+ * @v len		Length of plaintext handshake record
  * @ret rc		Return status code
  */
 static int tls_new_certificate ( struct tls_session *tls,
 				 void *data, size_t len ) {
 	struct {
-		uint32_t type_length;
 		uint8_t length[3];
-		uint8_t first_cert_length[3];
-		uint8_t asn1_start[0];
+		uint8_t certificates[0];
 	} __attribute__ (( packed )) *certificate = data;
-	uint8_t *cert = certificate->asn1_start;
-	int offset = 0;
-
-	/* FIXME */
-	(void) len;
-
-	if (asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0 ||
-	    asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0 ||
-            asn1_skip_obj(cert, &offset, ASN1_EXPLICIT_TAG) ||
-            asn1_skip_obj(cert, &offset, ASN1_INTEGER) ||
-            asn1_skip_obj(cert, &offset, ASN1_SEQUENCE) ||
-            asn1_skip_obj(cert, &offset, ASN1_SEQUENCE) ||
-            asn1_skip_obj(cert, &offset, ASN1_SEQUENCE) ||
-            asn1_skip_obj(cert, &offset, ASN1_SEQUENCE) ||
-	    asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0 ||
-            asn1_skip_obj(cert, &offset, ASN1_SEQUENCE) ||
-            asn1_next_obj(cert, &offset, ASN1_BIT_STRING) < 0) {
-		DBGC ( tls, "TLS %p invalid certificate\n", tls );
-		DBGC_HD ( tls, cert + offset, 64 );
-		return -EPERM;
-	}
-	
-	offset++;
-	
-	if (asn1_next_obj(cert, &offset, ASN1_SEQUENCE) < 0) {
-		DBGC ( tls, "TLS %p invalid certificate\n", tls );
-		DBGC_HD ( tls, cert + offset, 64 );
-		return -EPERM;
+	struct {
+		uint8_t length[3];
+		uint8_t certificate[0];
+	} __attribute__ (( packed )) *element =
+		  ( ( void * ) certificate->certificates );
+	size_t elements_len = tls_uint24 ( certificate->length );
+	void *end = ( certificate->certificates + elements_len );
+	struct asn1_cursor cursor;
+	int rc;
+
+	/* Sanity check */
+	if ( end != ( data + len ) ) {
+		DBGC ( tls, "TLS %p received overlength Server Certificate\n",
+		       tls );
+		DBGC_HD ( tls, data, len );
+		return -EINVAL;
 	}
-	
-	tls->rsa_mod_len = asn1_get_int(cert, &offset, &tls->rsa_mod);
-	tls->rsa_pub_exp_len = asn1_get_int(cert, &offset, &tls->rsa_pub_exp);
-	
-	DBGC_HD ( tls, tls->rsa_mod, tls->rsa_mod_len );
-	DBGC_HD ( tls, tls->rsa_pub_exp, tls->rsa_pub_exp_len );
 
-	return 0;
+	/* Traverse certificate chain */
+	do {
+		cursor.data = element->certificate;
+		cursor.len = tls_uint24 ( element->length );
+		if ( ( cursor.data + cursor.len ) > end ) {
+			DBGC ( tls, "TLS %p received corrupt Server "
+			       "Certificate\n", tls );
+			DBGC_HD ( tls, data, len );
+			return -EINVAL;
+		}
+
+		// HACK
+		if ( ( rc = x509_rsa_public_key ( &cursor,
+						  &tls->rsa ) ) != 0 ) {
+			DBGC ( tls, "TLS %p cannot determine RSA public key: "
+			       "%s\n", tls, strerror ( rc ) );
+			return rc;
+		}
+		return 0;
+
+		element = ( cursor.data + cursor.len );
+	} while ( element != end );
+
+	return -EINVAL;
 }
 
 /**
- * Receive new Server Hello Done record
+ * Receive new Server Hello Done handshake record
  *
  * @v tls		TLS session
- * @v data		Plaintext record
- * @v len		Length of plaintext record
+ * @v data		Plaintext handshake record
+ * @v len		Length of plaintext handshake record
  * @ret rc		Return status code
  */
 static int tls_new_server_hello_done ( struct tls_session *tls,
 				       void *data, size_t len ) {
 	struct {
-		uint32_t type_length;
 		char next[0];
 	} __attribute__ (( packed )) *hello_done = data;
 	void *end = hello_done->next;
@@ -910,11 +939,11 @@ static int tls_new_server_hello_done ( struct tls_session *tls,
 }
 
 /**
- * Receive new Finished record
+ * Receive new Finished handshake record
  *
  * @v tls		TLS session
- * @v data		Plaintext record
- * @v len		Length of plaintext record
+ * @v data		Plaintext handshake record
+ * @v len		Length of plaintext handshake record
  * @ret rc		Return status code
  */
 static int tls_new_finished ( struct tls_session *tls,
@@ -937,33 +966,47 @@ static int tls_new_finished ( struct tls_session *tls,
  */
 static int tls_new_handshake ( struct tls_session *tls,
 			       void *data, size_t len ) {
-	uint8_t *type = data;
+	struct {
+		uint8_t type;
+		uint8_t length[3];
+		uint8_t payload[0];
+	} __attribute__ (( packed )) *handshake = data;
+	void *payload = &handshake->payload;
+	size_t payload_len = tls_uint24 ( handshake->length );
+	void *end = ( payload + payload_len );
 	int rc;
 
-	switch ( *type ) {
+	/* Sanity check */
+	if ( end != ( data + len ) ) {
+		DBGC ( tls, "TLS %p received overlength Handshake\n", tls );
+		DBGC_HD ( tls, data, len );
+		return -EINVAL;
+	}
+
+	switch ( handshake->type ) {
 	case TLS_SERVER_HELLO:
-		rc = tls_new_server_hello ( tls, data, len );
+		rc = tls_new_server_hello ( tls, payload, payload_len );
 		break;
 	case TLS_CERTIFICATE:
-		rc = tls_new_certificate ( tls, data, len );
+		rc = tls_new_certificate ( tls, payload, payload_len );
 		break;
 	case TLS_SERVER_HELLO_DONE:
-		rc = tls_new_server_hello_done ( tls, data, len );
+		rc = tls_new_server_hello_done ( tls, payload, payload_len );
 		break;
 	case TLS_FINISHED:
-		rc = tls_new_finished ( tls, data, len );
+		rc = tls_new_finished ( tls, payload, payload_len );
 		break;
 	default:
 		DBGC ( tls, "TLS %p ignoring handshake type %d\n",
-		       tls, *type );
+		       tls, handshake->type );
 		rc = 0;
 		break;
 	}
 
 	/* Add to handshake digest (except for Hello Requests, which
-	 * are explicitly excludede).
+	 * are explicitly excluded).
 	 */
-	if ( *type != TLS_HELLO_REQUEST )
+	if ( handshake->type != TLS_HELLO_REQUEST )
 		tls_add_handshake ( tls, data, len );
 
 	return rc;