1 files changed, 496 insertions, 0 deletions

diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
new file mode 100644
index 0000000..7fabc4c
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -0,0 +1,496 @@
+/* X.509 certificate parser
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "X.509: "fmt
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/oid_registry.h>
+#include "public_key.h"
+#include "x509_parser.h"
+#include "x509-asn1.h"
+#include "x509_rsakey-asn1.h"
+
+struct x509_parse_context {
+	struct x509_certificate	*cert;		/* Certificate being constructed */
+	unsigned long	data;			/* Start of data */
+	const void	*cert_start;		/* Start of cert content */
+	const void	*key;			/* Key data */
+	size_t		key_size;		/* Size of key data */
+	enum OID	last_oid;		/* Last OID encountered */
+	enum OID	algo_oid;		/* Algorithm OID */
+	unsigned char	nr_mpi;			/* Number of MPIs stored */
+	u8		o_size;			/* Size of organizationName (O) */
+	u8		cn_size;		/* Size of commonName (CN) */
+	u8		email_size;		/* Size of emailAddress */
+	u16		o_offset;		/* Offset of organizationName (O) */
+	u16		cn_offset;		/* Offset of commonName (CN) */
+	u16		email_offset;		/* Offset of emailAddress */
+};
+
+/*
+ * Free an X.509 certificate
+ */
+void x509_free_certificate(struct x509_certificate *cert)
+{
+	if (cert) {
+		public_key_destroy(cert->pub);
+		kfree(cert->issuer);
+		kfree(cert->subject);
+		kfree(cert->fingerprint);
+		kfree(cert->authority);
+		kfree(cert);
+	}
+}
+
+/*
+ * Parse an X.509 certificate
+ */
+struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
+{
+	struct x509_certificate *cert;
+	struct x509_parse_context *ctx;
+	long ret;
+
+	ret = -ENOMEM;
+	cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
+	if (!cert)
+		goto error_no_cert;
+	cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
+	if (!cert->pub)
+		goto error_no_ctx;
+	ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
+	if (!ctx)
+		goto error_no_ctx;
+
+	ctx->cert = cert;
+	ctx->data = (unsigned long)data;
+
+	/* Attempt to decode the certificate */
+	ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
+	if (ret < 0)
+		goto error_decode;
+
+	/* Decode the public key */
+	ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
+			       ctx->key, ctx->key_size);
+	if (ret < 0)
+		goto error_decode;
+
+	kfree(ctx);
+	return cert;
+
+error_decode:
+	kfree(ctx);
+error_no_ctx:
+	x509_free_certificate(cert);
+error_no_cert:
+	return ERR_PTR(ret);
+}
+
+/*
+ * Note an OID when we find one for later processing when we know how
+ * to interpret it.
+ */
+int x509_note_OID(void *context, size_t hdrlen,
+	     unsigned char tag,
+	     const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	ctx->last_oid = look_up_OID(value, vlen);
+	if (ctx->last_oid == OID__NR) {
+		char buffer[50];
+		sprint_oid(value, vlen, buffer, sizeof(buffer));
+		pr_debug("Unknown OID: [%lu] %s\n",
+			 (unsigned long)value - ctx->data, buffer);
+	}
+	return 0;
+}
+
+/*
+ * Save the position of the TBS data so that we can check the signature over it
+ * later.
+ */
+int x509_note_tbs_certificate(void *context, size_t hdrlen,
+			      unsigned char tag,
+			      const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
+		 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
+
+	ctx->cert->tbs = value - hdrlen;
+	ctx->cert->tbs_size = vlen + hdrlen;
+	return 0;
+}
+
+/*
+ * Record the public key algorithm
+ */
+int x509_note_pkey_algo(void *context, size_t hdrlen,
+			unsigned char tag,
+			const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	pr_debug("PubKey Algo: %u\n", ctx->last_oid);
+
+	switch (ctx->last_oid) {
+	case OID_md2WithRSAEncryption:
+	case OID_md3WithRSAEncryption:
+	default:
+		return -ENOPKG; /* Unsupported combination */
+
+	case OID_md4WithRSAEncryption:
+		ctx->cert->sig_hash_algo = PKEY_HASH_MD5;
+		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+		break;
+
+	case OID_sha1WithRSAEncryption:
+		ctx->cert->sig_hash_algo = PKEY_HASH_SHA1;
+		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+		break;
+
+	case OID_sha256WithRSAEncryption:
+		ctx->cert->sig_hash_algo = PKEY_HASH_SHA256;
+		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+		break;
+
+	case OID_sha384WithRSAEncryption:
+		ctx->cert->sig_hash_algo = PKEY_HASH_SHA384;
+		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+		break;
+
+	case OID_sha512WithRSAEncryption:
+		ctx->cert->sig_hash_algo = PKEY_HASH_SHA512;
+		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+		break;
+
+	case OID_sha224WithRSAEncryption:
+		ctx->cert->sig_hash_algo = PKEY_HASH_SHA224;
+		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
+		break;
+	}
+
+	ctx->algo_oid = ctx->last_oid;
+	return 0;
+}
+
+/*
+ * Note the whereabouts and type of the signature.
+ */
+int x509_note_signature(void *context, size_t hdrlen,
+			unsigned char tag,
+			const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
+
+	if (ctx->last_oid != ctx->algo_oid) {
+		pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
+			ctx->algo_oid, ctx->last_oid);
+		return -EINVAL;
+	}
+
+	ctx->cert->sig = value;
+	ctx->cert->sig_size = vlen;
+	return 0;
+}
+
+/*
+ * Note some of the name segments from which we'll fabricate a name.
+ */
+int x509_extract_name_segment(void *context, size_t hdrlen,
+			      unsigned char tag,
+			      const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	switch (ctx->last_oid) {
+	case OID_commonName:
+		ctx->cn_size = vlen;
+		ctx->cn_offset = (unsigned long)value - ctx->data;
+		break;
+	case OID_organizationName:
+		ctx->o_size = vlen;
+		ctx->o_offset = (unsigned long)value - ctx->data;
+		break;
+	case OID_email_address:
+		ctx->email_size = vlen;
+		ctx->email_offset = (unsigned long)value - ctx->data;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+/*
+ * Fabricate and save the issuer and subject names
+ */
+static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
+			       unsigned char tag,
+			       char **_name, size_t vlen)
+{
+	const void *name, *data = (const void *)ctx->data;
+	size_t namesize;
+	char *buffer;
+
+	if (*_name)
+		return -EINVAL;
+
+	/* Empty name string if no material */
+	if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
+		buffer = kmalloc(1, GFP_KERNEL);
+		if (!buffer)
+			return -ENOMEM;
+		buffer[0] = 0;
+		goto done;
+	}
+
+	if (ctx->cn_size && ctx->o_size) {
+		/* Consider combining O and CN, but use only the CN if it is
+		 * prefixed by the O, or a significant portion thereof.
+		 */
+		namesize = ctx->cn_size;
+		name = data + ctx->cn_offset;
+		if (ctx->cn_size >= ctx->o_size &&
+		    memcmp(data + ctx->cn_offset, data + ctx->o_offset,
+			   ctx->o_size) == 0)
+			goto single_component;
+		if (ctx->cn_size >= 7 &&
+		    ctx->o_size >= 7 &&
+		    memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
+			goto single_component;
+
+		buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
+				 GFP_KERNEL);
+		if (!buffer)
+			return -ENOMEM;
+
+		memcpy(buffer,
+		       data + ctx->o_offset, ctx->o_size);
+		buffer[ctx->o_size + 0] = ':';
+		buffer[ctx->o_size + 1] = ' ';
+		memcpy(buffer + ctx->o_size + 2,
+		       data + ctx->cn_offset, ctx->cn_size);
+		buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
+		goto done;
+
+	} else if (ctx->cn_size) {
+		namesize = ctx->cn_size;
+		name = data + ctx->cn_offset;
+	} else if (ctx->o_size) {
+		namesize = ctx->o_size;
+		name = data + ctx->o_offset;
+	} else {
+		namesize = ctx->email_size;
+		name = data + ctx->email_offset;
+	}
+
+single_component:
+	buffer = kmalloc(namesize + 1, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+	memcpy(buffer, name, namesize);
+	buffer[namesize] = 0;
+
+done:
+	*_name = buffer;
+	ctx->cn_size = 0;
+	ctx->o_size = 0;
+	ctx->email_size = 0;
+	return 0;
+}
+
+int x509_note_issuer(void *context, size_t hdrlen,
+		     unsigned char tag,
+		     const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
+}
+
+int x509_note_subject(void *context, size_t hdrlen,
+		      unsigned char tag,
+		      const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
+}
+
+/*
+ * Extract the data for the public key algorithm
+ */
+int x509_extract_key_data(void *context, size_t hdrlen,
+			  unsigned char tag,
+			  const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	if (ctx->last_oid != OID_rsaEncryption)
+		return -ENOPKG;
+
+	/* There seems to be an extraneous 0 byte on the front of the data */
+	ctx->cert->pkey_algo = PKEY_ALGO_RSA;
+	ctx->key = value + 1;
+	ctx->key_size = vlen - 1;
+	return 0;
+}
+
+/*
+ * Extract a RSA public key value
+ */
+int rsa_extract_mpi(void *context, size_t hdrlen,
+		    unsigned char tag,
+		    const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	MPI mpi;
+
+	if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
+		pr_err("Too many public key MPIs in certificate\n");
+		return -EBADMSG;
+	}
+
+	mpi = mpi_read_raw_data(value, vlen);
+	if (!mpi)
+		return -ENOMEM;
+
+	ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
+	return 0;
+}
+
+/*
+ * Process certificate extensions that are used to qualify the certificate.
+ */
+int x509_process_extension(void *context, size_t hdrlen,
+			   unsigned char tag,
+			   const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	const unsigned char *v = value;
+	char *f;
+	int i;
+
+	pr_debug("Extension: %u\n", ctx->last_oid);
+
+	if (ctx->last_oid == OID_subjectKeyIdentifier) {
+		/* Get hold of the key fingerprint */
+		if (vlen < 3)
+			return -EBADMSG;
+		if (v[0] != ASN1_OTS || v[1] != vlen - 2)
+			return -EBADMSG;
+		v += 2;
+		vlen -= 2;
+
+		f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
+		if (!f)
+			return -ENOMEM;
+		for (i = 0; i < vlen; i++)
+			sprintf(f + i * 2, "%02x", v[i]);
+		pr_debug("fingerprint %s\n", f);
+		ctx->cert->fingerprint = f;
+		return 0;
+	}
+
+	if (ctx->last_oid == OID_authorityKeyIdentifier) {
+		/* Get hold of the CA key fingerprint */
+		if (vlen < 5)
+			return -EBADMSG;
+		if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)) ||
+		    v[1] != vlen - 2 ||
+		    v[2] != (ASN1_CONT << 6) ||
+		    v[3] != vlen - 4)
+			return -EBADMSG;
+		v += 4;
+		vlen -= 4;
+
+		f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
+		if (!f)
+			return -ENOMEM;
+		for (i = 0; i < vlen; i++)
+			sprintf(f + i * 2, "%02x", v[i]);
+		pr_debug("authority   %s\n", f);
+		ctx->cert->authority = f;
+		return 0;
+	}
+
+	return 0;
+}
+
+/*
+ * Record a certificate time.
+ */
+static int x509_note_time(struct tm *tm,  size_t hdrlen,
+			  unsigned char tag,
+			  const unsigned char *value, size_t vlen)
+{
+	const unsigned char *p = value;
+
+#define dec2bin(X) ((X) - '0')
+#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
+
+	if (tag == ASN1_UNITIM) {
+		/* UTCTime: YYMMDDHHMMSSZ */
+		if (vlen != 13)
+			goto unsupported_time;
+		tm->tm_year = DD2bin(p);
+		if (tm->tm_year >= 50)
+			tm->tm_year += 1900;
+		else
+			tm->tm_year += 2000;
+	} else if (tag == ASN1_GENTIM) {
+		/* GenTime: YYYYMMDDHHMMSSZ */
+		if (vlen != 15)
+			goto unsupported_time;
+		tm->tm_year = DD2bin(p) * 100 + DD2bin(p);
+	} else {
+		goto unsupported_time;
+	}
+
+	tm->tm_year -= 1900;
+	tm->tm_mon  = DD2bin(p) - 1;
+	tm->tm_mday = DD2bin(p);
+	tm->tm_hour = DD2bin(p);
+	tm->tm_min  = DD2bin(p);
+	tm->tm_sec  = DD2bin(p);
+
+	if (*p != 'Z')
+		goto unsupported_time;
+
+	return 0;
+
+unsupported_time:
+	pr_debug("Got unsupported time [tag %02x]: '%*.*s'\n",
+		 tag, (int)vlen, (int)vlen, value);
+	return -EBADMSG;
+}
+
+int x509_note_not_before(void *context, size_t hdrlen,
+			 unsigned char tag,
+			 const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	return x509_note_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
+}
+
+int x509_note_not_after(void *context, size_t hdrlen,
+			unsigned char tag,
+			const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
+}