X.509: Add simple ASN.1 grammar compiler

Add a simple ASN.1 grammar compiler.  This produces a bytecode output that can
be fed to a decoder to inform the decoder how to interpret the ASN.1 stream it
is trying to parse.

Action functions can be specified in the grammar by interpolating:

	({ foo })

after a type, for example:

	SubjectPublicKeyInfo ::= SEQUENCE {
		algorithm		AlgorithmIdentifier,
		subjectPublicKey	BIT STRING ({ do_key_data })
		}

The decoder is expected to call these after matching this type and parsing the
contents if it is a constructed type.

The grammar compiler does not currently support the SET type (though it does
support SET OF) as I can't see a good way of tracking which members have been
encountered yet without using up extra stack space.

Currently, the grammar compiler will fail if more than 256 bytes of bytecode
would be produced or more than 256 actions have been specified as it uses
8-bit jump values and action indices to keep space usage down.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 67 insertions, 0 deletions

diff --git a/include/linux/asn1.h b/include/linux/asn1.h
new file mode 100644
index 000000000000..5c3f4e4b9a23
--- /dev/null
+++ b/include/linux/asn1.h
@@ -0,0 +1,67 @@
+/* ASN.1 BER/DER/CER encoding definitions
+ *
+ * Copyright (C) 2012 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_ASN1_H
+#define _LINUX_ASN1_H
+
+/* Class */
+enum asn1_class {
+	ASN1_UNIV	= 0,	/* Universal */
+	ASN1_APPL	= 1,	/* Application */
+	ASN1_CONT	= 2,	/* Context */
+	ASN1_PRIV	= 3	/* Private */
+};
+#define ASN1_CLASS_BITS	0xc0
+
+
+enum asn1_method {
+	ASN1_PRIM	= 0,	/* Primitive */
+	ASN1_CONS	= 1	/* Constructed */
+};
+#define ASN1_CONS_BIT	0x20
+
+/* Tag */
+enum asn1_tag {
+	ASN1_EOC	= 0,	/* End Of Contents or N/A */
+	ASN1_BOOL	= 1,	/* Boolean */
+	ASN1_INT	= 2,	/* Integer */
+	ASN1_BTS	= 3,	/* Bit String */
+	ASN1_OTS	= 4,	/* Octet String */
+	ASN1_NULL	= 5,	/* Null */
+	ASN1_OID	= 6,	/* Object Identifier  */
+	ASN1_ODE	= 7,	/* Object Description */
+	ASN1_EXT	= 8,	/* External */
+	ASN1_REAL	= 9,	/* Real float */
+	ASN1_ENUM	= 10,	/* Enumerated */
+	ASN1_EPDV	= 11,	/* Embedded PDV */
+	ASN1_UTF8STR	= 12,	/* UTF8 String */
+	ASN1_RELOID	= 13,	/* Relative OID */
+	/* 14 - Reserved */
+	/* 15 - Reserved */
+	ASN1_SEQ	= 16,	/* Sequence and Sequence of */
+	ASN1_SET	= 17,	/* Set and Set of */
+	ASN1_NUMSTR	= 18,	/* Numerical String */
+	ASN1_PRNSTR	= 19,	/* Printable String */
+	ASN1_TEXSTR	= 20,	/* T61 String / Teletext String */
+	ASN1_VIDSTR	= 21,	/* Videotex String */
+	ASN1_IA5STR	= 22,	/* IA5 String */
+	ASN1_UNITIM	= 23,	/* Universal Time */
+	ASN1_GENTIM	= 24,	/* General Time */
+	ASN1_GRASTR	= 25,	/* Graphic String */
+	ASN1_VISSTR	= 26,	/* Visible String */
+	ASN1_GENSTR	= 27,	/* General String */
+	ASN1_UNISTR	= 28,	/* Universal String */
+	ASN1_CHRSTR	= 29,	/* Character String */
+	ASN1_BMPSTR	= 30,	/* BMP String */
+	ASN1_LONG_TAG	= 31	/* Long form tag */
+};
+
+#endif /* _LINUX_ASN1_H */