crypto: rsa - limit supported key lengths

Introduce constrains for RSA keys lengths.
Only key lengths of 512, 1024, 1536, 2048, 3072, and 4096 bits
will be supported.

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

diff --git a/crypto/rsa.c b/crypto/rsa.c
index 752af06..466003e 100644 (file)
--- a/crypto/rsa.c
+++ b/crypto/rsa.c
@@ -267,12 +267,36 @@ err_free_m:
        return ret;
 }
 
+static int rsa_check_key_length(unsigned int len)
+{
+       switch (len) {
+       case 512:
+       case 1024:
+       case 1536:
+       case 2048:
+       case 3072:
+       case 4096:
+               return 0;
+       }
+
+       return -EINVAL;
+}
+
 static int rsa_setkey(struct crypto_akcipher *tfm, const void *key,
                      unsigned int keylen)
 {
        struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
+       int ret;
 
-       return rsa_parse_key(pkey, key, keylen);
+       ret = rsa_parse_key(pkey, key, keylen);
+       if (ret)
+               return ret;
+
+       if (rsa_check_key_length(mpi_get_size(pkey->n) << 3)) {
+               rsa_free_key(pkey);
+               ret = -EINVAL;
+       }
+       return ret;
 }
 
 static void rsa_exit_tfm(struct crypto_akcipher *tfm)