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Subject[PATCH 05/22] KEYS: Provide software public key query function
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Date
Provide a query function for the software public key implementation.  This
permits information about such a key to be obtained using
query_asymmetric_key() or KEYCTL_PKEY_QUERY.

Signed-off-by: David Howells <dhowells@redhat.com>
---

crypto/asymmetric_keys/public_key.c | 99 +++++++++++++++++++++++++++++------
1 file changed, 82 insertions(+), 17 deletions(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index e929fe1e4106..761bfab352dc 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -59,6 +59,81 @@ static void public_key_destroy(void *payload0, void *payload3)
public_key_signature_free(payload3);
}

+/*
+ * Determine the crypto algorithm name.
+ */
+static
+int software_key_determine_akcipher(const char *encoding,
+ const char *hash_algo,
+ const struct public_key *pkey,
+ char alg_name[CRYPTO_MAX_ALG_NAME])
+{
+ int n;
+
+ if (strcmp(encoding, "pkcs1") == 0) {
+ /* The data wangled by the RSA algorithm is typically padded
+ * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
+ * sec 8.2].
+ */
+ if (!hash_algo)
+ n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
+ "pkcs1pad(%s)",
+ pkey->pkey_algo);
+ else
+ n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
+ "pkcs1pad(%s,%s)",
+ pkey->pkey_algo, hash_algo);
+ return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
+ }
+
+ if (strcmp(encoding, "raw") == 0) {
+ strcpy(alg_name, pkey->pkey_algo);
+ return 0;
+ }
+
+ return -ENOPKG;
+}
+
+/*
+ * Query information about a key.
+ */
+static int software_key_query(const struct kernel_pkey_params *params,
+ struct kernel_pkey_query *info)
+{
+ struct crypto_akcipher *tfm;
+ struct public_key *pkey = params->key->payload.data[asym_crypto];
+ char alg_name[CRYPTO_MAX_ALG_NAME];
+ int ret, len;
+
+ ret = software_key_determine_akcipher(params->encoding,
+ params->hash_algo,
+ pkey, alg_name);
+ if (ret < 0)
+ return ret;
+
+ tfm = crypto_alloc_akcipher(alg_name, 0, 0);
+ if (IS_ERR(tfm))
+ return PTR_ERR(tfm);
+
+ ret = crypto_akcipher_set_pub_key(tfm, pkey->key, pkey->keylen);
+ if (ret < 0)
+ goto error_free_tfm;
+
+ len = crypto_akcipher_maxsize(tfm);
+ info->key_size = len * 8;
+ info->max_data_size = len;
+ info->max_sig_size = len;
+ info->max_enc_size = len;
+ info->max_dec_size = len;
+ info->supported_ops = KEYCTL_SUPPORTS_VERIFY;
+ ret = 0;
+
+error_free_tfm:
+ crypto_free_akcipher(tfm);
+ pr_devel("<==%s() = %d\n", __func__, ret);
+ return ret;
+}
+
/*
* Verify a signature using a public key.
*/
@@ -69,8 +144,7 @@ int public_key_verify_signature(const struct public_key *pkey,
struct crypto_akcipher *tfm;
struct akcipher_request *req;
struct scatterlist sig_sg, digest_sg;
- const char *alg_name;
- char alg_name_buf[CRYPTO_MAX_ALG_NAME];
+ char alg_name[CRYPTO_MAX_ALG_NAME];
void *output;
unsigned int outlen;
int ret;
@@ -81,21 +155,11 @@ int public_key_verify_signature(const struct public_key *pkey,
BUG_ON(!sig);
BUG_ON(!sig->s);

- if (!sig->digest)
- return -ENOPKG;
-
- alg_name = sig->pkey_algo;
- if (strcmp(sig->pkey_algo, "rsa") == 0) {
- /* The data wangled by the RSA algorithm is typically padded
- * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
- * sec 8.2].
- */
- if (snprintf(alg_name_buf, CRYPTO_MAX_ALG_NAME,
- "pkcs1pad(rsa,%s)", sig->hash_algo
- ) >= CRYPTO_MAX_ALG_NAME)
- return -EINVAL;
- alg_name = alg_name_buf;
- }
+ ret = software_key_determine_akcipher(sig->encoding,
+ sig->hash_algo,
+ pkey, alg_name);
+ if (ret < 0)
+ return ret;

tfm = crypto_alloc_akcipher(alg_name, 0, 0);
if (IS_ERR(tfm))
@@ -167,6 +231,7 @@ struct asymmetric_key_subtype public_key_subtype = {
.name_len = sizeof("public_key") - 1,
.describe = public_key_describe,
.destroy = public_key_destroy,
+ .query = software_key_query,
.verify_signature = public_key_verify_signature_2,
};
EXPORT_SYMBOL_GPL(public_key_subtype);
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