KEYS: Provide key type operations for asymmetric key ops [ver #2]

Provide five new operations in the key_type struct that can be used to
provide access to asymmetric key operations.  These will be implemented for
the asymmetric key type in a later patch and may refer to a key retained in
RAM by the kernel or a key retained in crypto hardware.

     int (*asym_query)(const struct kernel_pkey_params *params,
		       struct kernel_pkey_query *info);
     int (*asym_eds_op)(struct kernel_pkey_params *params,
			const void *in, void *out);
     int (*asym_verify_signature)(struct kernel_pkey_params *params,
			          const void *in, const void *in2);

Since encrypt, decrypt and sign are identical in their interfaces, they're
rolled together in the asym_eds_op() operation and there's an operation ID
in the params argument to distinguish them.

Verify is different in that we supply the data and the signature instead
and get an error value (or 0) as the only result on the expectation that
this may well be how a hardware crypto device may work.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Denis Kenzior <denkenz@gmail.com>
Tested-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

3 files changed, 62 insertions, 0 deletions

diff --git a/include/linux/key-type.h b/include/linux/key-type.h
index 05d8fb5a06c4..bc9af551fc83 100644
--- a/include/linux/key-type.h
+++ b/include/linux/key-type.h
@@ -17,6 +17,9 @@
 
 #ifdef CONFIG_KEYS
 
+struct kernel_pkey_query;
+struct kernel_pkey_params;
+
 /*
  * key under-construction record
  * - passed to the request_key actor if supplied
@@ -155,6 +158,14 @@ struct key_type {
 	 */
 	struct key_restriction *(*lookup_restriction)(const char *params);
 
+	/* Asymmetric key accessor functions. */
+	int (*asym_query)(const struct kernel_pkey_params *params,
+			  struct kernel_pkey_query *info);
+	int (*asym_eds_op)(struct kernel_pkey_params *params,
+			   const void *in, void *out);
+	int (*asym_verify_signature)(struct kernel_pkey_params *params,
+				     const void *in, const void *in2);
+
 	/* internal fields */
 	struct list_head	link;		/* link in types list */
 	struct lock_class_key	lock_class;	/* key->sem lock class */
diff --git a/include/linux/keyctl.h b/include/linux/keyctl.h
new file mode 100644
index 000000000000..c7c48c79ce0e
--- /dev/null
+++ b/include/linux/keyctl.h
@@ -0,0 +1,46 @@
+/* keyctl kernel bits
+ *
+ * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef __LINUX_KEYCTL_H
+#define __LINUX_KEYCTL_H
+
+#include <uapi/linux/keyctl.h>
+
+struct kernel_pkey_query {
+	__u32		supported_ops;	/* Which ops are supported */
+	__u32		key_size;	/* Size of the key in bits */
+	__u16		max_data_size;	/* Maximum size of raw data to sign in bytes */
+	__u16		max_sig_size;	/* Maximum size of signature in bytes */
+	__u16		max_enc_size;	/* Maximum size of encrypted blob in bytes */
+	__u16		max_dec_size;	/* Maximum size of decrypted blob in bytes */
+};
+
+enum kernel_pkey_operation {
+	kernel_pkey_encrypt,
+	kernel_pkey_decrypt,
+	kernel_pkey_sign,
+	kernel_pkey_verify,
+};
+
+struct kernel_pkey_params {
+	struct key	*key;
+	const char	*encoding;	/* Encoding (eg. "oaep" or "raw" for none) */
+	const char	*hash_algo;	/* Digest algorithm used (eg. "sha1") or NULL if N/A */
+	char		*info;		/* Modified info string to be released later */
+	__u32		in_len;		/* Input data size */
+	union {
+		__u32	out_len;	/* Output buffer size (enc/dec/sign) */
+		__u32	in2_len;	/* 2nd input data size (verify) */
+	};
+	enum kernel_pkey_operation op : 8;
+};
+
+#endif /* __LINUX_KEYCTL_H */
diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
index 0f3cb13db8e9..1d1e9f2877af 100644
--- a/include/uapi/linux/keyctl.h
+++ b/include/uapi/linux/keyctl.h
@@ -82,4 +82,9 @@ struct keyctl_kdf_params {
 	__u32 __spare[8];
 };
 
+#define KEYCTL_SUPPORTS_ENCRYPT		0x01
+#define KEYCTL_SUPPORTS_DECRYPT		0x02
+#define KEYCTL_SUPPORTS_SIGN		0x04
+#define KEYCTL_SUPPORTS_VERIFY		0x08
+
 #endif /*  _LINUX_KEYCTL_H */