[PATCH] lib/crypto: Enable more algorithms in cert verification

[Ilias Apalodimas]

Right now the code explicitly limits us to sha1,256 hashes with RSA2048
encryption.  But the limitation is artificial since U-Boot supports
a wider range of algorithms.

The internal image_get_[checksum|crypto]_algo() functions expect an
argument in the format of <checksum>,<crypto>.  So let's remove the size
checking and create the needed string on the fly in order to support
more hash/signing combinations.

Signed-off-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
---
 lib/crypto/public_key.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/lib/crypto/public_key.c b/lib/crypto/public_key.c
index df6033cdb499..b783c63f5a51 100644
--- a/lib/crypto/public_key.c
+++ b/lib/crypto/public_key.c
@@ -97,6 +97,7 @@ int public_key_verify_signature(const struct public_key *pkey,
                                const struct public_key_signature *sig)
 {
        struct image_sign_info info;
+       char algo[256];
        int ret;
 
        pr_devel("==>%s()\n", __func__);
@@ -108,29 +109,27 @@ int public_key_verify_signature(const struct public_key 
*pkey,
                return -EINVAL;
 
        memset(&info, '\0', sizeof(info));
+       memset(algo, 0, sizeof(algo));
        info.padding = image_get_padding_algo("pkcs-1.5");
        /*
         * Note: image_get_[checksum|crypto]_algo takes a string
         * argument like "<checksum>,<crypto>"
         * TODO: support other hash algorithms
         */
-       if (strcmp(sig->pkey_algo, "rsa") || (sig->s_size * 8) != 2048) {
-               pr_warn("Encryption is not RSA2048: %s%d\n",
-                       sig->pkey_algo, sig->s_size * 8);
-               return -ENOPKG;
-       }
-       if (!strcmp(sig->hash_algo, "sha1")) {
-               info.checksum = image_get_checksum_algo("sha1,rsa2048");
-               info.name = "sha1,rsa2048";
-       } else if (!strcmp(sig->hash_algo, "sha256")) {
-               info.checksum = image_get_checksum_algo("sha256,rsa2048");
-               info.name = "sha256,rsa2048";
-       } else {
-               pr_warn("unknown msg digest algo: %s\n", sig->hash_algo);
+       if (strcmp(sig->pkey_algo, "rsa")) {
+               pr_err("Encryption is not RSA: %s\n", sig->pkey_algo);
                return -ENOPKG;
        }
+       ret = snprintf(algo, sizeof(algo), "%s,%s%d", sig->hash_algo,
+                      sig->pkey_algo, sig->s_size * 8);
+
+       if (ret >= sizeof(algo))
+               return -EINVAL;
+
+       info.checksum = image_get_checksum_algo((const char *)algo);
+       info.name = (const char *)algo;
        info.crypto = image_get_crypto_algo(info.name);
-       if (IS_ERR(info.checksum) || IS_ERR(info.crypto))
+       if (!info.checksum || !info.crypto)
                return -ENOPKG;
 
        info.key = pkey->key;
-- 
2.30.2