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>

1 files changed, 41 insertions, 18 deletions

diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c
index 812476e46821..cfc04e15fd97 100644
--- 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;