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Subject[RFC PATCH v3] akcipher: Introduce verify_rsa/verify for public key algorithms
Date
Previous akcipher .verify() just `decrypts' (using RSA encrypt which is
using public key) signature to uncover message hash, which was then
compared in upper level public_key_verify_signature() with the expected
hash value, which itself was never passed into verify().

This approach was incompatible with EC-DSA family of algorithms,
because, to verify a signature EC-DSA algorithm also needs a hash value
as input; then it's used (together with a signature divided into halves
`r||s') to produce a witness value, which is then compared with `r' to
determine if the signature is correct. Thus, for EC-DSA, nor
requirements of .verify() itself, nor its output expectations in
public_key_verify_signature() wasn't sufficient.

Make improved .verify() call which gets hash value as parameter and
produce complete signature check without any output besides status.

RSA-centric drivers have replaced verify() with verify_rsa() which
have old semantic and which they still should implement (if they want
pkcs1pad to work). If akcipher have .verify_rsa() callback, it will be
used for a partial verification, which then is finished in
crypto_akcipher_verify().

Now for the top level verification only crypto_akcipher_verify() needs
to be called.

For pkcs1pad crypto_akcipher_verify_rsa() is introduced which directly
calls .verify_rsa() for its backend. Without this api PKCS1 can not be
implemented.

Tested on x86_64.

Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
---

This should be applied over cryptodev tree.

Changes since v2:
- `output` is factored out from public_key_verify_signature() into
crypto_akcipher_verify().
- in crypto_akcipher_verify_rsa() -ENOSYS error is added for robustness (if,
in the future, some RSA driver will not implement this api).
- api descriptions are updated to be more clear.

Changes since v1:
- complete rework to the different approach and should be treated as
a new patch.

crypto/akcipher.c | 60 +++++++++++++++++++++++++++
crypto/asymmetric_keys/public_key.c | 32 ++------------
crypto/rsa-pkcs1pad.c | 4 +-
crypto/rsa.c | 2 +-
crypto/testmgr.c | 43 ++++++++++---------
drivers/crypto/caam/caampkc.c | 2 +-
drivers/crypto/ccp/ccp-crypto-rsa.c | 2 +-
drivers/crypto/qat/qat_common/qat_asym_algs.c | 2 +-
include/crypto/akcipher.h | 34 ++++++++++-----
9 files changed, 117 insertions(+), 64 deletions(-)

diff --git a/crypto/akcipher.c b/crypto/akcipher.c
index 0cbeae137e0a..95f207b2eb12 100644
--- a/crypto/akcipher.c
+++ b/crypto/akcipher.c
@@ -25,6 +25,66 @@
#include <crypto/internal/akcipher.h>
#include "internal.h"

+/**
+ * crypto_akcipher_verify() - Invoke public key signature verification
+ *
+ * Function invokes the specific public key signature verification operation
+ * for a given public key algorithm.
+ *
+ * @req: asymmetric key request
+ * @digest: expected hash value
+ * @digest_len: hash length
+ *
+ * Return: zero on verification success; error code in case of error.
+ */
+int crypto_akcipher_verify(struct akcipher_request *req,
+ const unsigned char *digest, unsigned int digest_len)
+{
+ struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
+ struct akcipher_alg *alg = crypto_akcipher_alg(tfm);
+ struct crypto_alg *calg = tfm->base.__crt_alg;
+ int ret;
+
+ if (WARN_ON(!digest || !digest_len) ||
+ WARN_ON(req->dst || req->dst_len))
+ return -EINVAL;
+
+ crypto_stats_get(calg);
+ if (alg->verify_rsa) {
+ struct scatterlist output_sg;
+ void *output;
+ unsigned int outlen;
+
+ outlen = crypto_akcipher_maxsize(tfm);
+ ret = -EKEYREJECTED;
+ if (WARN_ON(outlen < digest_len))
+ goto out;
+ ret = -ENOMEM;
+ output = kmalloc(outlen, GFP_KERNEL);
+ if (!output)
+ goto out;
+ sg_init_one(&output_sg, output, outlen);
+ akcipher_request_set_crypt(req, req->src, &output_sg,
+ req->src_len, outlen);
+
+ /* Perform the verification calculation. This doesn't actually
+ * do the verification, but rather calculates the hash expected
+ * by the signature and returns that to us.
+ */
+ ret = crypto_akcipher_verify_rsa(req);
+ if (!ret &&
+ (req->dst_len != digest_len ||
+ memcmp(digest, output, digest_len)))
+ ret = -EKEYREJECTED;
+ kfree(output);
+ } else
+ ret = alg->verify(req, digest, digest_len);
+out:
+ crypto_stats_akcipher_verify(ret, calg);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(crypto_akcipher_verify);
+
#ifdef CONFIG_NET
static int crypto_akcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index f5d85b47fcc6..73724f74d124 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -227,10 +227,8 @@ int public_key_verify_signature(const struct public_key *pkey,
struct crypto_wait cwait;
struct crypto_akcipher *tfm;
struct akcipher_request *req;
- struct scatterlist sig_sg, digest_sg;
+ struct scatterlist sig_sg;
char alg_name[CRYPTO_MAX_ALG_NAME];
- void *output;
- unsigned int outlen;
int ret;

pr_devel("==>%s()\n", __func__);
@@ -263,36 +261,14 @@ int public_key_verify_signature(const struct public_key *pkey,
if (ret)
goto error_free_req;

- ret = -ENOMEM;
- outlen = crypto_akcipher_maxsize(tfm);
- output = kmalloc(outlen, GFP_KERNEL);
- if (!output)
- goto error_free_req;
-
sg_init_one(&sig_sg, sig->s, sig->s_size);
- sg_init_one(&digest_sg, output, outlen);
- akcipher_request_set_crypt(req, &sig_sg, &digest_sg, sig->s_size,
- outlen);
+ akcipher_request_set_crypt(req, &sig_sg, NULL, sig->s_size, 0);
crypto_init_wait(&cwait);
akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
CRYPTO_TFM_REQ_MAY_SLEEP,
crypto_req_done, &cwait);
-
- /* Perform the verification calculation. This doesn't actually do the
- * verification, but rather calculates the hash expected by the
- * signature and returns that to us.
- */
- ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
- if (ret)
- goto out_free_output;
-
- /* Do the actual verification step. */
- if (req->dst_len != sig->digest_size ||
- memcmp(sig->digest, output, sig->digest_size) != 0)
- ret = -EKEYREJECTED;
-
-out_free_output:
- kfree(output);
+ ret = crypto_wait_req(crypto_akcipher_verify(req, sig->digest,
+ sig->digest_size), &cwait);
error_free_req:
akcipher_request_free(req);
error_free_tfm:
diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c
index 0a6680ca8cb6..88728ffb6b69 100644
--- a/crypto/rsa-pkcs1pad.c
+++ b/crypto/rsa-pkcs1pad.c
@@ -551,7 +551,7 @@ static int pkcs1pad_verify(struct akcipher_request *req)
req_ctx->out_sg, req->src_len,
ctx->key_size);

- err = crypto_akcipher_verify(&req_ctx->child_req);
+ err = crypto_akcipher_verify_rsa(&req_ctx->child_req);
if (err != -EINPROGRESS && err != -EBUSY)
return pkcs1pad_verify_complete(req, err);

@@ -675,7 +675,7 @@ static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
inst->alg.encrypt = pkcs1pad_encrypt;
inst->alg.decrypt = pkcs1pad_decrypt;
inst->alg.sign = pkcs1pad_sign;
- inst->alg.verify = pkcs1pad_verify;
+ inst->alg.verify_rsa = pkcs1pad_verify;
inst->alg.set_pub_key = pkcs1pad_set_pub_key;
inst->alg.set_priv_key = pkcs1pad_set_priv_key;
inst->alg.max_size = pkcs1pad_get_max_size;
diff --git a/crypto/rsa.c b/crypto/rsa.c
index 4167980c243d..42df7d0c915c 100644
--- a/crypto/rsa.c
+++ b/crypto/rsa.c
@@ -354,7 +354,7 @@ static struct akcipher_alg rsa = {
.encrypt = rsa_enc,
.decrypt = rsa_dec,
.sign = rsa_sign,
- .verify = rsa_verify,
+ .verify_rsa = rsa_verify,
.set_priv_key = rsa_set_priv_key,
.set_pub_key = rsa_set_pub_key,
.max_size = rsa_max_size,
diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index e4f3f5f688e7..eb2adcf606d2 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -2275,13 +2275,12 @@ static int test_akcipher_one(struct crypto_akcipher *tfm,
if (err)
goto free_req;

- err = -ENOMEM;
- out_len_max = crypto_akcipher_maxsize(tfm);
-
/*
* First run test which do not require a private key, such as
* encrypt or verify.
*/
+ err = -ENOMEM;
+ out_len_max = crypto_akcipher_maxsize(tfm);
outbuf_enc = kzalloc(out_len_max, GFP_KERNEL);
if (!outbuf_enc)
goto free_req;
@@ -2310,33 +2309,39 @@ static int test_akcipher_one(struct crypto_akcipher *tfm,
sg_init_table(src_tab, 2);
sg_set_buf(&src_tab[0], xbuf[0], 8);
sg_set_buf(&src_tab[1], xbuf[0] + 8, m_size - 8);
- sg_init_one(&dst, outbuf_enc, out_len_max);
- akcipher_request_set_crypt(req, src_tab, &dst, m_size,
- out_len_max);
+ if (vecs->siggen_sigver_test)
+ akcipher_request_set_crypt(req, src_tab, NULL, m_size, 0);
+ else {
+ sg_init_one(&dst, outbuf_enc, out_len_max);
+ akcipher_request_set_crypt(req, src_tab, &dst, m_size,
+ out_len_max);
+ }
akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &wait);

err = crypto_wait_req(vecs->siggen_sigver_test ?
/* Run asymmetric signature verification */
- crypto_akcipher_verify(req) :
+ crypto_akcipher_verify(req, c, c_size) :
/* Run asymmetric encrypt */
crypto_akcipher_encrypt(req), &wait);
if (err) {
pr_err("alg: akcipher: %s test failed. err %d\n", op, err);
goto free_all;
}
- if (req->dst_len != c_size) {
- pr_err("alg: akcipher: %s test failed. Invalid output len\n",
- op);
- err = -EINVAL;
- goto free_all;
- }
- /* verify that encrypted message is equal to expected */
- if (memcmp(c, outbuf_enc, c_size)) {
- pr_err("alg: akcipher: %s test failed. Invalid output\n", op);
- hexdump(outbuf_enc, c_size);
- err = -EINVAL;
- goto free_all;
+ if (!vecs->siggen_sigver_test) {
+ if (req->dst_len != c_size) {
+ pr_err("alg: akcipher: %s test failed. Invalid output len\n",
+ op);
+ err = -EINVAL;
+ goto free_all;
+ }
+ /* verify that encrypted message is equal to expected */
+ if (memcmp(c, outbuf_enc, c_size)) {
+ pr_err("alg: akcipher: %s test failed. Invalid output\n", op);
+ hexdump(outbuf_enc, c_size);
+ err = -EINVAL;
+ goto free_all;
+ }
}

/*
diff --git a/drivers/crypto/caam/caampkc.c b/drivers/crypto/caam/caampkc.c
index 77ab28a2811a..e06b4c9a89e2 100644
--- a/drivers/crypto/caam/caampkc.c
+++ b/drivers/crypto/caam/caampkc.c
@@ -995,7 +995,7 @@ static struct akcipher_alg caam_rsa = {
.encrypt = caam_rsa_enc,
.decrypt = caam_rsa_dec,
.sign = caam_rsa_dec,
- .verify = caam_rsa_enc,
+ .verify_rsa = caam_rsa_enc,
.set_pub_key = caam_rsa_set_pub_key,
.set_priv_key = caam_rsa_set_priv_key,
.max_size = caam_rsa_max_size,
diff --git a/drivers/crypto/ccp/ccp-crypto-rsa.c b/drivers/crypto/ccp/ccp-crypto-rsa.c
index 05850dfd7940..fc669b1bb328 100644
--- a/drivers/crypto/ccp/ccp-crypto-rsa.c
+++ b/drivers/crypto/ccp/ccp-crypto-rsa.c
@@ -215,7 +215,7 @@ static struct akcipher_alg ccp_rsa_defaults = {
.encrypt = ccp_rsa_encrypt,
.decrypt = ccp_rsa_decrypt,
.sign = ccp_rsa_decrypt,
- .verify = ccp_rsa_encrypt,
+ .verify_rsa = ccp_rsa_encrypt,
.set_pub_key = ccp_rsa_setpubkey,
.set_priv_key = ccp_rsa_setprivkey,
.max_size = ccp_rsa_maxsize,
diff --git a/drivers/crypto/qat/qat_common/qat_asym_algs.c b/drivers/crypto/qat/qat_common/qat_asym_algs.c
index 320e7854b4ee..a6c7ff572970 100644
--- a/drivers/crypto/qat/qat_common/qat_asym_algs.c
+++ b/drivers/crypto/qat/qat_common/qat_asym_algs.c
@@ -1301,7 +1301,7 @@ static struct akcipher_alg rsa = {
.encrypt = qat_rsa_enc,
.decrypt = qat_rsa_dec,
.sign = qat_rsa_dec,
- .verify = qat_rsa_enc,
+ .verify_rsa = qat_rsa_enc,
.set_pub_key = qat_rsa_setpubkey,
.set_priv_key = qat_rsa_setprivkey,
.max_size = qat_rsa_max_size,
diff --git a/include/crypto/akcipher.h b/include/crypto/akcipher.h
index 2d690494568c..286f529024ba 100644
--- a/include/crypto/akcipher.h
+++ b/include/crypto/akcipher.h
@@ -55,10 +55,14 @@ struct crypto_akcipher {
* algorithm. In case of error, where the dst_len was insufficient,
* the req->dst_len will be updated to the size required for the
* operation
- * @verify: Function performs a sign operation as defined by public key
- * algorithm. In case of error, where the dst_len was insufficient,
- * the req->dst_len will be updated to the size required for the
- * operation
+ * @verify_rsa: Function performs a partial verify operation as defined by RSA
+ * algorithm producing signature in the output. In case of error,
+ * where the dst_len was insufficient, the req->dst_len will be
+ * updated to the size required for the operation. All RSA
+ * implementations that could be PKCS1 padded should implement that.
+ * @verify: Function performs a complete verify operation as defined by public
+ * key algorithm, returning verification status. Requires digest
+ * value as input parameter.
* @encrypt: Function performs an encrypt operation as defined by public key
* algorithm. In case of error, where the dst_len was insufficient,
* the req->dst_len will be updated to the size required for the
@@ -91,7 +95,9 @@ struct crypto_akcipher {
*/
struct akcipher_alg {
int (*sign)(struct akcipher_request *req);
- int (*verify)(struct akcipher_request *req);
+ int (*verify_rsa)(struct akcipher_request *req);
+ int (*verify)(struct akcipher_request *req, const u8 *digest,
+ unsigned int digest_len);
int (*encrypt)(struct akcipher_request *req);
int (*decrypt)(struct akcipher_request *req);
int (*set_pub_key)(struct crypto_akcipher *tfm, const void *key,
@@ -343,24 +349,26 @@ static inline int crypto_akcipher_sign(struct akcipher_request *req)
}

/**
- * crypto_akcipher_verify() - Invoke public key verify operation
+ * crypto_akcipher_verify_rsa() - Invoke partial RSA verify operation
*
- * Function invokes the specific public key verify operation for a given
- * public key algorithm
+ * Function invokes partial verify operation for a RSA algorithm
*
* @req: asymmetric key request
*
+ * Note: this should only be used by RSA wrappers such as PKCS1.
+ *
* Return: zero on success; error code in case of error
*/
-static inline int crypto_akcipher_verify(struct akcipher_request *req)
+static inline int crypto_akcipher_verify_rsa(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct akcipher_alg *alg = crypto_akcipher_alg(tfm);
struct crypto_alg *calg = tfm->base.__crt_alg;
- int ret;
+ int ret = -ENOSYS;

crypto_stats_get(calg);
- ret = alg->verify(req);
+ if (alg->verify_rsa)
+ ret = alg->verify_rsa(req);
crypto_stats_akcipher_verify(ret, calg);
return ret;
}
@@ -406,4 +414,8 @@ static inline int crypto_akcipher_set_priv_key(struct crypto_akcipher *tfm,

return alg->set_priv_key(tfm, key, keylen);
}
+
+int crypto_akcipher_verify(struct akcipher_request *req,
+ const unsigned char *digest,
+ unsigned int digest_len);
#endif
--
2.11.0
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