s390/pkey: Introduce new API for secure key verification

User space needs some information about the secure key(s)
before actually invoking the pkey and/or paes funcionality.
This patch introduces a new ioctl API and in kernel API to
verify the the secure key blob and give back some
information about the key (type, bitsize, old MKVP).
Both APIs are described in detail in the header files
arch/s390/include/asm/pkey.h and arch/s390/include/uapi/asm/pkey.h.

Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 63 insertions, 1 deletions

diff --git a/drivers/s390/crypto/pkey_api.c b/drivers/s390/crypto/pkey_api.c
index 058db724b5a2..ea86da8c75f9 100644
--- a/drivers/s390/crypto/pkey_api.c
+++ b/drivers/s390/crypto/pkey_api.c
@@ -80,7 +80,7 @@ struct secaeskeytoken {
  * token. If keybitsize is given, the bitsize of the key is
  * also checked. Returns 0 on success or errno value on failure.
  */
-static int check_secaeskeytoken(u8 *token, int keybitsize)
+static int check_secaeskeytoken(const u8 *token, int keybitsize)
 {
 	struct secaeskeytoken *t = (struct secaeskeytoken *) token;
 
@@ -1004,6 +1004,53 @@ int pkey_skey2pkey(const struct pkey_seckey *seckey,
 EXPORT_SYMBOL(pkey_skey2pkey);
 
 /*
+ * Verify key and give back some info about the key.
+ */
+int pkey_verifykey(const struct pkey_seckey *seckey,
+		   u16 *pcardnr, u16 *pdomain,
+		   u16 *pkeysize, u32 *pattributes)
+{
+	struct secaeskeytoken *t = (struct secaeskeytoken *) seckey;
+	u16 cardnr, domain;
+	u64 mkvp[2];
+	int rc;
+
+	/* check the secure key for valid AES secure key */
+	rc = check_secaeskeytoken((u8 *) seckey, 0);
+	if (rc)
+		goto out;
+	if (pattributes)
+		*pattributes = PKEY_VERIFY_ATTR_AES;
+	if (pkeysize)
+		*pkeysize = t->bitsize;
+
+	/* try to find a card which can handle this key */
+	rc = pkey_findcard(seckey, &cardnr, &domain, 1);
+	if (rc)
+		goto out;
+
+	/* check mkvp for old mkvp match */
+	rc = mkvp_cache_fetch(cardnr, domain, mkvp);
+	if (rc)
+		goto out;
+	if (t->mkvp == mkvp[1]) {
+		DEBUG_DBG("pkey_verifykey secure key has old mkvp\n");
+		if (pattributes)
+			*pattributes |= PKEY_VERIFY_ATTR_OLD_MKVP;
+	}
+
+	if (pcardnr)
+		*pcardnr = cardnr;
+	if (pdomain)
+		*pdomain = domain;
+
+out:
+	DEBUG_DBG("pkey_verifykey rc=%d\n", rc);
+	return rc;
+}
+EXPORT_SYMBOL(pkey_verifykey);
+
+/*
  * File io functions
  */
 
@@ -1104,6 +1151,21 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 			return -EFAULT;
 		break;
 	}
+	case PKEY_VERIFYKEY: {
+		struct pkey_verifykey __user *uvk = (void __user *) arg;
+		struct pkey_verifykey kvk;
+
+		if (copy_from_user(&kvk, uvk, sizeof(kvk)))
+			return -EFAULT;
+		rc = pkey_verifykey(&kvk.seckey, &kvk.cardnr, &kvk.domain,
+				    &kvk.keysize, &kvk.attributes);
+		DEBUG_DBG("pkey_ioctl pkey_verifykey()=%d\n", rc);
+		if (rc)
+			break;
+		if (copy_to_user(uvk, &kvk, sizeof(kvk)))
+			return -EFAULT;
+		break;
+	}
 	default:
 		/* unknown/unsupported ioctl cmd */
 		return -ENOTTY;