crypto: rsa-pkcs1pad: Allow hash to be optional [ver #2]

The original pkcs1pad implementation allowed to pad/unpad raw RSA
output.  However, this has been taken out in commit:
commit c0d20d22e0ad ("crypto: rsa-pkcs1pad - Require hash to be present")

This patch restored this ability as it is needed by the asymmetric key
implementation.

Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>

diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c
index 812476e..cfc04e1 100644 (file)
--- a/crypto/rsa-pkcs1pad.c
+++ b/crypto/rsa-pkcs1pad.c
@@ -392,7 +392,8 @@ static int pkcs1pad_sign(struct akcipher_request *req)
        if (!ctx->key_size)
                return -EINVAL;
 
-       digest_size = digest_info->size;
+       if (digest_info)
+               digest_size = digest_info->size;
 
        if (req->src_len + digest_size > ctx->key_size - 11)
                return -EOVERFLOW;
@@ -412,8 +413,9 @@ static int pkcs1pad_sign(struct akcipher_request *req)
        memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
        req_ctx->in_buf[ps_end] = 0x00;
 
-       memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
-              digest_info->size);
+       if (digest_info)
+               memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
+                      digest_info->size);
 
        pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
                        ctx->key_size - 1 - req->src_len, req->src);
@@ -475,10 +477,13 @@ static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
                goto done;
        pos++;
 
-       if (crypto_memneq(out_buf + pos, digest_info->data, digest_info->size))
-               goto done;
+       if (digest_info) {
+               if (crypto_memneq(out_buf + pos, digest_info->data,
+                                 digest_info->size))
+                       goto done;
 
-       pos += digest_info->size;
+               pos += digest_info->size;
+       }
 
        err = 0;
 
@@ -608,11 +613,14 @@ static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
 
        hash_name = crypto_attr_alg_name(tb[2]);
        if (IS_ERR(hash_name))
-               return PTR_ERR(hash_name);
+               hash_name = NULL;
 
-       digest_info = rsa_lookup_asn1(hash_name);
-       if (!digest_info)
-               return -EINVAL;
+       if (hash_name) {
+               digest_info = rsa_lookup_asn1(hash_name);
+               if (!digest_info)
+                       return -EINVAL;
+       } else
+               digest_info = NULL;
 
        inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
        if (!inst)
@@ -632,14 +640,29 @@ static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
 
        err = -ENAMETOOLONG;
 
-       if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
-                    "pkcs1pad(%s,%s)", rsa_alg->base.cra_name, hash_name) >=
-           CRYPTO_MAX_ALG_NAME ||
-           snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
-                    "pkcs1pad(%s,%s)",
-                    rsa_alg->base.cra_driver_name, hash_name) >=
-           CRYPTO_MAX_ALG_NAME)
-               goto out_drop_alg;
+       if (!hash_name) {
+               if (snprintf(inst->alg.base.cra_name,
+                            CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
+                            rsa_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
+                       goto out_drop_alg;
+
+               if (snprintf(inst->alg.base.cra_driver_name,
+                            CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
+                            rsa_alg->base.cra_driver_name) >=
+                            CRYPTO_MAX_ALG_NAME)
+                       goto out_drop_alg;
+       } else {
+               if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
+                            "pkcs1pad(%s,%s)", rsa_alg->base.cra_name,
+                            hash_name) >= CRYPTO_MAX_ALG_NAME)
+                       goto out_drop_alg;
+
+               if (snprintf(inst->alg.base.cra_driver_name,
+                            CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s,%s)",
+                            rsa_alg->base.cra_driver_name,
+                            hash_name) >= CRYPTO_MAX_ALG_NAME)
+                       goto out_drop_alg;
+       }
 
        inst->alg.base.cra_flags = rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC;
        inst->alg.base.cra_priority = rsa_alg->base.cra_priority;