s390/pkey: Introduce new API for random protected key verification

Introduce a new ioctl API and in-kernel API to verify if a
random protected key is still valid. A protected key is
invalid when its wrapping key verification pattern does not
match the verification pattern of the LPAR. Each time an LPAR
is activated, a new LPAR wrapping key is generated and the
wrapping key verification pattern is updated.
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: Ingo Franzki <ifranzki@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/pkey.h

@@ -117,4 +117,12 @@ int pkey_verifykey(const struct pkey_seckey *seckey,
  */
 int pkey_genprotkey(__u32 keytype, struct pkey_protkey *protkey);
 
+/*
+ * In-kernel API: Verify an (AES) protected key.
+ * @param protkey pointer to buffer containing the protected key to verify
+ * @return 0 on success, negative errno value on failure. In case the protected
+ * key is not valid -EKEYREJECTED is returned
+ */
+int pkey_verifyprotkey(const struct pkey_protkey *protkey);
+
 #endif /* _KAPI_PKEY_H */

arch/s390/include/uapi/asm/pkey.h

@@ -139,4 +139,13 @@ struct pkey_genprotk {
 
 #define PKEY_GENPROTK _IOWR(PKEY_IOCTL_MAGIC, 0x08, struct pkey_genprotk)
 
+/*
+ * Verify an (AES) protected key.
+ */
+struct pkey_verifyprotk {
+	struct pkey_protkey protkey;	/* in: the protected key to verify */
+};
+
+#define PKEY_VERIFYPROTK _IOW(PKEY_IOCTL_MAGIC, 0x09, struct pkey_verifyprotk)
+
 #endif /* _UAPI_PKEY_H */

drivers/s390/crypto/pkey_api.c

@@ -20,6 +20,7 @@
 #include <asm/zcrypt.h>
 #include <asm/cpacf.h>
 #include <asm/pkey.h>
+#include <crypto/aes.h>
 
 #include "zcrypt_api.h"
 
@@ -1113,6 +1114,52 @@ int pkey_genprotkey(__u32 keytype, struct pkey_protkey *protkey)
 }
 EXPORT_SYMBOL(pkey_genprotkey);
 
+/*
+ * Verify if a protected key is still valid
+ */
+int pkey_verifyprotkey(const struct pkey_protkey *protkey)
+{
+	unsigned long fc;
+	struct {
+		u8 iv[AES_BLOCK_SIZE];
+		u8 key[MAXPROTKEYSIZE];
+	} param;
+	u8 null_msg[AES_BLOCK_SIZE];
+	u8 dest_buf[AES_BLOCK_SIZE];
+	unsigned int k;
+
+	switch (protkey->type) {
+	case PKEY_KEYTYPE_AES_128:
+		fc = CPACF_KMC_PAES_128;
+		break;
+	case PKEY_KEYTYPE_AES_192:
+		fc = CPACF_KMC_PAES_192;
+		break;
+	case PKEY_KEYTYPE_AES_256:
+		fc = CPACF_KMC_PAES_256;
+		break;
+	default:
+		DEBUG_ERR("%s unknown/unsupported keytype %d\n", __func__,
+			  protkey->type);
+		return -EINVAL;
+	}
+
+	memset(null_msg, 0, sizeof(null_msg));
+
+	memset(param.iv, 0, sizeof(param.iv));
+	memcpy(param.key, protkey->protkey, sizeof(param.key));
+
+	k = cpacf_kmc(fc | CPACF_ENCRYPT, &param, null_msg, dest_buf,
+		      sizeof(null_msg));
+	if (k != sizeof(null_msg)) {
+		DEBUG_ERR("%s protected key is not valid\n", __func__);
+		return -EKEYREJECTED;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(pkey_verifyprotkey);
+
 /*
  * File io functions
  */
@@ -1243,6 +1290,16 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 			return -EFAULT;
 		break;
 	}
+	case PKEY_VERIFYPROTK: {
+		struct pkey_verifyprotk __user *uvp = (void __user *) arg;
+		struct pkey_verifyprotk kvp;
+
+		if (copy_from_user(&kvp, uvp, sizeof(kvp)))
+			return -EFAULT;
+		rc = pkey_verifyprotkey(&kvp.protkey);
+		DEBUG_DBG("%s pkey_verifyprotkey()=%d\n", __func__, rc);
+		break;
+	}
 	default:
 		/* unknown/unsupported ioctl cmd */
 		return -ENOTTY;
@@ -1504,7 +1561,7 @@ static struct miscdevice pkey_dev = {
  */
 static int __init pkey_init(void)
 {
-	cpacf_mask_t pckmo_functions;
+	cpacf_mask_t pckmo_functions, kmc_functions;
 
 	/* check for pckmo instructions available */
 	if (!cpacf_query(CPACF_PCKMO, &pckmo_functions))
@@ -1514,6 +1571,14 @@ static int __init pkey_init(void)
 	    !cpacf_test_func(&pckmo_functions, CPACF_PCKMO_ENC_AES_256_KEY))
 		return -EOPNOTSUPP;
 
+	/* check for kmc instructions available */
+	if (!cpacf_query(CPACF_KMC, &kmc_functions))
+		return -EOPNOTSUPP;
+	if (!cpacf_test_func(&kmc_functions, CPACF_KMC_PAES_128) ||
+	    !cpacf_test_func(&kmc_functions, CPACF_KMC_PAES_192) ||
+	    !cpacf_test_func(&kmc_functions, CPACF_KMC_PAES_256))
+		return -EOPNOTSUPP;
+
 	pkey_debug_init();
 
 	return misc_register(&pkey_dev);