akcipher: Move the RSA DER encoding check to the crypto layer

Move the RSA EMSA-PKCS1-v1_5 encoding from the asymmetric-key public_key
subtype to the rsa crypto module's pkcs1pad template.  This means that the
public_key subtype no longer has any dependencies on public key type.

To make this work, the following changes have been made:

 (1) The rsa pkcs1pad template is now used for RSA keys.  This strips off the
     padding and returns just the message hash.

 (2) In a previous patch, the pkcs1pad template gained an optional second
     parameter that, if given, specifies the hash used.  We now give this,
     and pkcs1pad checks the encoded message E(M) for the EMSA-PKCS1-v1_5
     encoding and verifies that the correct digest OID is present.

 (3) The crypto driver in crypto/asymmetric_keys/rsa.c is now reduced to
     something that doesn't care about what the encryption actually does
     and and has been merged into public_key.c.

 (4) CONFIG_PUBLIC_KEY_ALGO_RSA is gone.  Module signing must set
     CONFIG_CRYPTO_RSA=y instead.

Thoughts:

 (*) Should the encoding style (eg. raw, EMSA-PKCS1-v1_5) also be passed to
     the padding template?  Should there be multiple padding templates
     registered that share most of the code?

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 0 insertions, 224 deletions

diff --git a/crypto/asymmetric_keys/rsa.c b/crypto/asymmetric_keys/rsa.c
deleted file mode 100644
index 51502bca65e7..000000000000
--- a/crypto/asymmetric_keys/rsa.c
+++ /dev/null
@@ -1,224 +0,0 @@
-/* RSA asymmetric public-key algorithm [RFC3447]
- *
- * 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) "RSA: "fmt
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <crypto/akcipher.h>
-#include <crypto/public_key.h>
-#include <crypto/algapi.h>
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("RSA Public Key Algorithm");
-
-#define kenter(FMT, ...) \
-	pr_devel("==> %s("FMT")\n", __func__, ##__VA_ARGS__)
-#define kleave(FMT, ...) \
-	pr_devel("<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
-
-/*
- * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
- */
-static const u8 RSA_digest_info_MD5[] = {
-	0x30, 0x20, 0x30, 0x0C, 0x06, 0x08,
-	0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, /* OID */
-	0x05, 0x00, 0x04, 0x10
-};
-
-static const u8 RSA_digest_info_SHA1[] = {
-	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
-	0x2B, 0x0E, 0x03, 0x02, 0x1A,
-	0x05, 0x00, 0x04, 0x14
-};
-
-static const u8 RSA_digest_info_RIPE_MD_160[] = {
-	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
-	0x2B, 0x24, 0x03, 0x02, 0x01,
-	0x05, 0x00, 0x04, 0x14
-};
-
-static const u8 RSA_digest_info_SHA224[] = {
-	0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
-	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
-	0x05, 0x00, 0x04, 0x1C
-};
-
-static const u8 RSA_digest_info_SHA256[] = {
-	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
-	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
-	0x05, 0x00, 0x04, 0x20
-};
-
-static const u8 RSA_digest_info_SHA384[] = {
-	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
-	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
-	0x05, 0x00, 0x04, 0x30
-};
-
-static const u8 RSA_digest_info_SHA512[] = {
-	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
-	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
-	0x05, 0x00, 0x04, 0x40
-};
-
-static const struct {
-	const u8 *data;
-	size_t size;
-} RSA_ASN1_templates[PKEY_HASH__LAST] = {
-#define _(X) { RSA_digest_info_##X, sizeof(RSA_digest_info_##X) }
-	[HASH_ALGO_MD5]		= _(MD5),
-	[HASH_ALGO_SHA1]	= _(SHA1),
-	[HASH_ALGO_RIPE_MD_160]	= _(RIPE_MD_160),
-	[HASH_ALGO_SHA256]	= _(SHA256),
-	[HASH_ALGO_SHA384]	= _(SHA384),
-	[HASH_ALGO_SHA512]	= _(SHA512),
-	[HASH_ALGO_SHA224]	= _(SHA224),
-#undef _
-};
-
-struct rsa_completion {
-	struct completion completion;
-	int err;
-};
-
-/*
- * Perform the RSA signature verification.
- * @H: Value of hash of data and metadata
- * @EM: The computed signature value
- * @k: The size of EM (EM[0] is an invalid location but should hold 0x00)
- * @hash_size: The size of H
- * @asn1_template: The DigestInfo ASN.1 template
- * @asn1_size: Size of asm1_template[]
- */
-static int rsa_verify(const u8 *H, const u8 *EM, size_t k, size_t hash_size,
-		      const u8 *asn1_template, size_t asn1_size)
-{
-	unsigned PS_end, T_offset, i;
-
-	kenter(",,%zu,%zu,%zu", k, hash_size, asn1_size);
-
-	if (k < 2 + 1 + asn1_size + hash_size)
-		return -EBADMSG;
-
-	/* Decode the EMSA-PKCS1-v1_5
-	 * note: leading zeros are stripped by the RSA implementation
-	 */
-	if (EM[0] != 0x01) {
-		kleave(" = -EBADMSG [EM[0] == %02u]", EM[0]);
-		return -EBADMSG;
-	}
-
-	T_offset = k - (asn1_size + hash_size);
-	PS_end = T_offset - 1;
-	if (EM[PS_end] != 0x00) {
-		kleave(" = -EBADMSG [EM[T-1] == %02u]", EM[PS_end]);
-		return -EBADMSG;
-	}
-
-	for (i = 1; i < PS_end; i++) {
-		if (EM[i] != 0xff) {
-			kleave(" = -EBADMSG [EM[PS%x] == %02u]", i - 2, EM[i]);
-			return -EBADMSG;
-		}
-	}
-
-	if (crypto_memneq(asn1_template, EM + T_offset, asn1_size) != 0) {
-		kleave(" = -EBADMSG [EM[T] ASN.1 mismatch]");
-		return -EBADMSG;
-	}
-
-	if (crypto_memneq(H, EM + T_offset + asn1_size, hash_size) != 0) {
-		kleave(" = -EKEYREJECTED [EM[T] hash mismatch]");
-		return -EKEYREJECTED;
-	}
-
-	kleave(" = 0");
-	return 0;
-}
-
-static void public_key_verify_done(struct crypto_async_request *req, int err)
-{
-	struct rsa_completion *compl = req->data;
-
-	if (err == -EINPROGRESS)
-		return;
-
-	compl->err = err;
-	complete(&compl->completion);
-}
-
-int rsa_verify_signature(const struct public_key *pkey,
-			 const struct public_key_signature *sig)
-{
-	struct crypto_akcipher *tfm;
-	struct akcipher_request *req;
-	struct rsa_completion compl;
-	struct scatterlist sig_sg, sg_out;
-	void *outbuf = NULL;
-	unsigned int outlen = 0;
-	int ret = -ENOMEM;
-
-	tfm = crypto_alloc_akcipher("rsa", 0, 0);
-	if (IS_ERR(tfm))
-		goto error_out;
-
-	req = akcipher_request_alloc(tfm, GFP_KERNEL);
-	if (!req)
-		goto error_free_tfm;
-
-	ret = crypto_akcipher_set_pub_key(tfm, pkey->key, pkey->keylen);
-	if (ret)
-		goto error_free_req;
-
-	ret = -EINVAL;
-	outlen = crypto_akcipher_maxsize(tfm);
-	if (!outlen)
-		goto error_free_req;
-
-	/* Initialize the output buffer */
-	ret = -ENOMEM;
-	outbuf = kmalloc(outlen, GFP_KERNEL);
-	if (!outbuf)
-		goto error_free_req;
-
-	sg_init_one(&sig_sg, sig->s, sig->s_size);
-	sg_init_one(&sg_out, outbuf, outlen);
-	akcipher_request_set_crypt(req, &sig_sg, &sg_out, sig->s_size, outlen);
-	init_completion(&compl.completion);
-	akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
-				      CRYPTO_TFM_REQ_MAY_SLEEP,
-				      public_key_verify_done, &compl);
-
-	ret = crypto_akcipher_verify(req);
-	if (ret == -EINPROGRESS) {
-		wait_for_completion(&compl.completion);
-		ret = compl.err;
-	}
-
-	if (ret)
-		goto error_free_req;
-
-	/* Output from the operation is an encoded message (EM) of
-	 * length k octets.
-	 */
-	outlen = req->dst_len;
-	ret = rsa_verify(sig->digest, outbuf, outlen, sig->digest_size,
-			 RSA_ASN1_templates[sig->pkey_hash_algo].data,
-			 RSA_ASN1_templates[sig->pkey_hash_algo].size);
-error_free_req:
-	akcipher_request_free(req);
-error_free_tfm:
-	crypto_free_akcipher(tfm);
-error_out:
-	kfree(outbuf);
-	return ret;
-}
-EXPORT_SYMBOL_GPL(rsa_verify_signature);