[crypto] Add block cipher Galois/Counter mode of operation

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/aes.h

@@ -47,6 +47,7 @@ struct aes_context {
 extern struct cipher_algorithm aes_algorithm;
 extern struct cipher_algorithm aes_ecb_algorithm;
 extern struct cipher_algorithm aes_cbc_algorithm;
+extern struct cipher_algorithm aes_gcm_algorithm;
 
 int aes_wrap ( const void *kek, const void *src, void *dest, int nblk );
 int aes_unwrap ( const void *kek, const void *src, void *dest, int nblk );

src/include/ipxe/crypto.h

@@ -11,6 +11,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <stdint.h>
 #include <stddef.h>
+#include <assert.h>
 
 /** A message digest algorithm */
 struct digest_algorithm {

src/include/ipxe/gcm.h

@@ -0,0 +1,132 @@
+#ifndef _IPXE_GCM_H
+#define _IPXE_GCM_H
+
+/** @file
+ *
+ * Galois/Counter Mode (GCM)
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdint.h>
+#include <ipxe/crypto.h>
+
+/** A GCM counter */
+struct gcm_counter {
+	/** Initialisation vector */
+	uint8_t iv[12];
+	/** Counter value */
+	uint32_t value;
+} __attribute__ (( packed ));
+
+/** A GCM length pair */
+struct gcm_lengths {
+	/** Additional data length */
+	uint64_t add;
+	/** Data length */
+	uint64_t data;
+} __attribute__ (( packed ));
+
+/** A GCM block */
+union gcm_block {
+	/** Raw bytes */
+	uint8_t byte[16];
+	/** Raw words */
+	uint16_t word[8];
+	/** Raw dwords */
+	uint32_t dword[4];
+	/** Counter */
+	struct gcm_counter ctr;
+	/** Lengths */
+	struct gcm_lengths len;
+} __attribute__ (( packed ));
+
+/** GCM context */
+struct gcm_context {
+	/** Hash key (H) */
+	union gcm_block key;
+	/** Counter (Y) */
+	union gcm_block ctr;
+	/** Accumulated hash (X) */
+	union gcm_block hash;
+	/** Accumulated lengths */
+	union gcm_block len;
+	/** Underlying block cipher */
+	struct cipher_algorithm *raw_cipher;
+	/** Underlying block cipher context */
+	uint8_t raw_ctx[0];
+};
+
+extern void gcm_tag ( struct gcm_context *context, union gcm_block *tag );
+extern int gcm_setkey ( struct gcm_context *context, const void *key,
+			size_t keylen, struct cipher_algorithm *raw_cipher );
+extern void gcm_setiv ( struct gcm_context *context, const void *iv,
+			size_t ivlen );
+extern void gcm_encrypt ( struct gcm_context *context, const void *src,
+			  void *dst, size_t len );
+extern void gcm_decrypt ( struct gcm_context *context, const void *src,
+			  void *dst, size_t len );
+
+/**
+ * Create a GCM mode of behaviour of an existing cipher
+ *
+ * @v _cbc_name		Name for the new CBC cipher
+ * @v _cbc_cipher	New cipher algorithm
+ * @v _raw_cipher	Underlying cipher algorithm
+ * @v _raw_context	Context structure for the underlying cipher
+ * @v _blocksize	Cipher block size
+ */
+#define GCM_CIPHER( _gcm_name, _gcm_cipher, _raw_cipher, _raw_context,	\
+		    _blocksize )					\
+struct _gcm_name ## _context {						\
+	/** GCM context */						\
+	struct gcm_context gcm;						\
+	/** Underlying block cipher context */				\
+	_raw_context raw;						\
+};									\
+static int _gcm_name ## _setkey ( void *ctx, const void *key,		\
+				  size_t keylen ) {			\
+	struct _gcm_name ## _context *context = ctx;			\
+	linker_assert ( _blocksize == sizeof ( context->gcm.key ),	\
+			_gcm_name ## _unsupported_blocksize );		\
+	linker_assert ( ( ( void * ) &context->gcm ) == ctx,		\
+			_gcm_name ## _context_layout_error );		\
+	linker_assert ( ( ( void * ) &context->raw ) ==			\
+			( ( void * ) context->gcm.raw_ctx ),		\
+			_gcm_name ## _context_layout_error );		\
+	return gcm_setkey ( &context->gcm, key, keylen, &_raw_cipher );	\
+}									\
+static void _gcm_name ## _setiv ( void *ctx, const void *iv,		\
+				  size_t ivlen ) {			\
+	struct _gcm_name ## _context *context = ctx;			\
+	gcm_setiv ( &context->gcm, iv, ivlen );				\
+}									\
+static void _gcm_name ## _encrypt ( void *ctx, const void *src,		\
+				    void *dst, size_t len ) {		\
+	struct _gcm_name ## _context *context = ctx;			\
+	gcm_encrypt ( &context->gcm, src, dst, len );			\
+}									\
+static void _gcm_name ## _decrypt ( void *ctx, const void *src,		\
+				    void *dst, size_t len ) {		\
+	struct _gcm_name ## _context *context = ctx;			\
+	gcm_decrypt ( &context->gcm, src, dst, len );			\
+}									\
+static void _gcm_name ## _auth ( void *ctx, void *auth ) {		\
+	struct _gcm_name ## _context *context = ctx;			\
+	union gcm_block *tag = auth;					\
+	gcm_tag ( &context->gcm, tag );					\
+}									\
+struct cipher_algorithm _gcm_cipher = {					\
+	.name		= #_gcm_name,					\
+	.ctxsize	= sizeof ( struct _gcm_name ## _context ),	\
+	.blocksize	= 1,						\
+	.authsize	= sizeof ( union gcm_block ),			\
+	.setkey		= _gcm_name ## _setkey,				\
+	.setiv		= _gcm_name ## _setiv,				\
+	.encrypt	= _gcm_name ## _encrypt,			\
+	.decrypt	= _gcm_name ## _decrypt,			\
+	.auth		= _gcm_name ## _auth,				\
+};
+
+#endif /* _IPXE_GCM_H */