[RFC 1/3] abi_spec: basic definitions of constraints, args and syscalls

[alexander . levin]

This is a very simple definition of the syscall ABI we can build on. The idea
is to have a generic description of syscalls, their arguments and return
values we can use to audit the kernel's implementation vs the specs.

Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
 include/uapi/linux/abi_spec.h | 58 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 include/uapi/linux/abi_spec.h

diff --git a/include/uapi/linux/abi_spec.h b/include/uapi/linux/abi_spec.h
new file mode 100644
index 0000000..ad1a992
--- /dev/null
+++ b/include/uapi/linux/abi_spec.h
@@ -0,0 +1,58 @@
+#ifndef ABI_SPEC_H_
+#define ABI_SPEC_H_
+
+#include <linux/fcntl.h>
+#include <linux/stat.h>
+#define MAX_CONSTRAINTS 10
+#define MAX_ARGS 10
+
+#define	TYPE_FD		1
+#define TYPE_INT	2
+#define TYPE_PTR	3
+#define TYPE_STRING	4
+/* ... */
+
+#define CONSTRAINT_NON_NULL	(1<<0)
+#define CONSTRAINT_RANGE	(1<<1)
+#define CONSTRAINT_ADDRESS_TYPE	(1<<2)
+#define CONSTRAINT_FD_TYPE	(1<<3)
+#define CONSTRAINT_ERRNO	(1<<4)
+#define CONSTRAINT_BITMASK	(1<<5)
+#define CONSTRAINT_PATH		(1<<6)
+/* ... */
+/* A generic constraint on an argument or a return value */
+struct constraint {
+	unsigned int flags;		/* bitmask of applied constraints */
+	union {
+		struct {		/* int range */
+			int int_min;
+			int int_max;
+		};
+		unsigned long bitmask;	/* allowed flags bitmask */
+		unsigned long address_flags;	/* Type of allowed addr */
+		unsigned long fd_flags;	/* Type of allowed fd */
+	};
+};
+
+/* A generic argument (or return value) */
+struct argument {
+	const char *name;
+	int type;			/* should be a nicer way to do this */
+
+	unsigned int nconstraints;	/* can there be more than 1-2? */
+	struct constraint constraints[MAX_CONSTRAINTS];
+};
+
+/* A generic syscall */
+struct syscall_spec {
+	const char *name;
+	struct argument retval;
+
+	unsigned int nargs;
+	struct argument args[MAX_ARGS];
+};
+
+void abispec_check_pre(const struct syscall_spec *s, ...);
+void abispec_check_post(const struct syscall_spec *s, long retval, ...);
+
+#endif
-- 
2.7.4