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authorDenis Kenzior <denkenz@gmail.com>2018-10-09 17:49:13 +0100
committerJames Morris <james.morris@microsoft.com>2018-10-26 09:30:47 +0100
commita335974ae0883e045151a2160093a22aa02c3626 (patch)
tree90f9e64662c93ffaea99de3dc9097550ccd6020a /crypto
parentf884fe5a158f750e232b029e1fac0283e388e062 (diff)
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KEYS: asym_tpm: Implement the decrypt operation [ver #2]
This patch implements the pkey_decrypt operation using the private key blob. The blob is first loaded into the TPM via tpm_loadkey2. Once the handle is obtained, tpm_unbind operation is used to decrypt the data on the TPM and the result is returned. The key loaded by tpm_loadkey2 is then evicted via tpm_flushspecific operation. This patch assumes that the SRK authorization is a well known 20-byte of zeros and the same holds for the key authorization of the provided key. 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>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/asymmetric_keys/asym_tpm.c58
1 files changed, 57 insertions, 1 deletions
diff --git a/crypto/asymmetric_keys/asym_tpm.c b/crypto/asymmetric_keys/asym_tpm.c
index e893b5212222..6f5d5cf98910 100644
--- a/crypto/asymmetric_keys/asym_tpm.c
+++ b/crypto/asymmetric_keys/asym_tpm.c
@@ -341,7 +341,8 @@ static int tpm_key_query(const struct kernel_pkey_params *params,
info->max_enc_size = len;
info->max_dec_size = tk->key_len / 8;
- info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT;
+ info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT |
+ KEYCTL_SUPPORTS_DECRYPT;
ret = 0;
error_free_tfm:
@@ -411,6 +412,58 @@ error_free_tfm:
}
/*
+ * Decryption operation is performed with the private key in the TPM.
+ */
+static int tpm_key_decrypt(struct tpm_key *tk,
+ struct kernel_pkey_params *params,
+ const void *in, void *out)
+{
+ struct tpm_buf *tb;
+ uint32_t keyhandle;
+ uint8_t srkauth[SHA1_DIGEST_SIZE];
+ uint8_t keyauth[SHA1_DIGEST_SIZE];
+ int r;
+
+ pr_devel("==>%s()\n", __func__);
+
+ if (params->hash_algo)
+ return -ENOPKG;
+
+ if (strcmp(params->encoding, "pkcs1"))
+ return -ENOPKG;
+
+ tb = kzalloc(sizeof(*tb), GFP_KERNEL);
+ if (!tb)
+ return -ENOMEM;
+
+ /* TODO: Handle a non-all zero SRK authorization */
+ memset(srkauth, 0, sizeof(srkauth));
+
+ r = tpm_loadkey2(tb, SRKHANDLE, srkauth,
+ tk->blob, tk->blob_len, &keyhandle);
+ if (r < 0) {
+ pr_devel("loadkey2 failed (%d)\n", r);
+ goto error;
+ }
+
+ /* TODO: Handle a non-all zero key authorization */
+ memset(keyauth, 0, sizeof(keyauth));
+
+ r = tpm_unbind(tb, keyhandle, keyauth,
+ in, params->in_len, out, params->out_len);
+ if (r < 0)
+ pr_devel("tpm_unbind failed (%d)\n", r);
+
+ if (tpm_flushspecific(tb, keyhandle) < 0)
+ pr_devel("flushspecific failed (%d)\n", r);
+
+error:
+ kzfree(tb);
+ pr_devel("<==%s() = %d\n", __func__, r);
+ return r;
+}
+
+/*
* Do encryption, decryption and signing ops.
*/
static int tpm_key_eds_op(struct kernel_pkey_params *params,
@@ -424,6 +477,9 @@ static int tpm_key_eds_op(struct kernel_pkey_params *params,
case kernel_pkey_encrypt:
ret = tpm_key_encrypt(tk, params, in, out);
break;
+ case kernel_pkey_decrypt:
+ ret = tpm_key_decrypt(tk, params, in, out);
+ break;
default:
BUG();
}