[RFC v3 10/45] richacl: In-memory representation and helper functions

[Andreas Gruenbacher <andreas.gruenbacher@gmail.com>]

A richacl consists of an NFSv4 acl and an owner, group, and other mask.
These three masks correspond to the owner, group, and other file
permission bits, but they contain NFSv4 permissions instead of POSIX
permissions.

Each entry in the NFSv4 acl applies to the file owner (OWNER@), the owning
group (GROUP@), everyone (EVERYONE@), or to a specific uid or gid.

As in the standard POSIX file permission model, each process is the
owner, group, or other file class.  A richacl grants a requested access
only if the NFSv4 acl in the richacl grants the access (according to the
NFSv4 permission check algorithm), and the file mask that applies to the
process includes the requested permissions.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/Makefile             |   2 +
 fs/richacl_base.c       |  58 ++++++++++++
 include/linux/richacl.h | 247 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 307 insertions(+)
 create mode 100644 fs/richacl_base.c
 create mode 100644 include/linux/richacl.h

diff --git a/fs/Makefile b/fs/Makefile
index a88ac48..8f0a59c 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -47,6 +47,8 @@ obj-$(CONFIG_COREDUMP)		+= coredump.o
 obj-$(CONFIG_SYSCTL)		+= drop_caches.o
 
 obj-$(CONFIG_FHANDLE)		+= fhandle.o
+obj-$(CONFIG_FS_RICHACL)	+= richacl.o
+richacl-y			:= richacl_base.o
 
 obj-y				+= quota/
 
diff --git a/fs/richacl_base.c b/fs/richacl_base.c
new file mode 100644
index 0000000..164b902
--- /dev/null
+++ b/fs/richacl_base.c
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2006, 2010  Novell, Inc.
+ * Copyright (C) 2015  Red Hat, Inc.
+ * Written by Andreas Gruenbacher <agruen@kernel.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/richacl.h>
+
+MODULE_LICENSE("GPL");
+
+/**
+ * richacl_alloc  -  allocate a richacl
+ * @count:	number of entries
+ */
+struct richacl *
+richacl_alloc(int count, gfp_t gfp)
+{
+	size_t size = sizeof(struct richacl) + count * sizeof(struct richace);
+	struct richacl *acl = kzalloc(size, gfp);
+
+	if (acl) {
+		atomic_set(&acl->a_refcount, 1);
+		acl->a_count = count;
+	}
+	return acl;
+}
+EXPORT_SYMBOL_GPL(richacl_alloc);
+
+/**
+ * richacl_clone  -  create a copy of a richacl
+ */
+struct richacl *
+richacl_clone(const struct richacl *acl, gfp_t gfp)
+{
+	int count = acl->a_count;
+	size_t size = sizeof(struct richacl) + count * sizeof(struct richace);
+	struct richacl *dup = kmalloc(size, gfp);
+
+	if (dup) {
+		memcpy(dup, acl, size);
+		atomic_set(&dup->a_refcount, 1);
+	}
+	return dup;
+}
diff --git a/include/linux/richacl.h b/include/linux/richacl.h
new file mode 100644
index 0000000..1499e7d
--- /dev/null
+++ b/include/linux/richacl.h
@@ -0,0 +1,247 @@
+/*
+ * Copyright (C) 2006, 2010  Novell, Inc.
+ * Copyright (C) 2015  Red Hat, Inc.
+ * Written by Andreas Gruenbacher <agruen@kernel.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#ifndef __RICHACL_H
+#define __RICHACL_H
+
+#define RICHACE_OWNER_SPECIAL_ID	0
+#define RICHACE_GROUP_SPECIAL_ID	1
+#define RICHACE_EVERYONE_SPECIAL_ID	2
+
+struct richace {
+	unsigned short	e_type;
+	unsigned short	e_flags;
+	unsigned int	e_mask;
+	union {
+		kuid_t		uid;
+		kgid_t		gid;
+		unsigned int	special;
+	} e_id;
+};
+
+struct richacl {
+	atomic_t	a_refcount;
+	unsigned int	a_owner_mask;
+	unsigned int	a_group_mask;
+	unsigned int	a_other_mask;
+	unsigned short	a_count;
+	unsigned short	a_flags;
+	struct richace	a_entries[0];
+};
+
+#define richacl_for_each_entry(_ace, _acl) \
+	for (_ace = (_acl)->a_entries; \
+	     _ace != (_acl)->a_entries + (_acl)->a_count; \
+	     _ace++)
+
+#define richacl_for_each_entry_reverse(_ace, _acl) \
+	for (_ace = (_acl)->a_entries + (_acl)->a_count - 1; \
+	     _ace != (_acl)->a_entries - 1; \
+	     _ace--)
+
+/* a_flag values */
+#define RICHACL_MASKED				0x80
+
+#define RICHACL_VALID_FLAGS (					\
+		RICHACL_MASKED)
+
+/* e_type values */
+#define RICHACE_ACCESS_ALLOWED_ACE_TYPE		0x0000
+#define RICHACE_ACCESS_DENIED_ACE_TYPE		0x0001
+
+/* e_flags bitflags */
+#define RICHACE_FILE_INHERIT_ACE		0x0001
+#define RICHACE_DIRECTORY_INHERIT_ACE		0x0002
+#define RICHACE_NO_PROPAGATE_INHERIT_ACE	0x0004
+#define RICHACE_INHERIT_ONLY_ACE		0x0008
+#define RICHACE_IDENTIFIER_GROUP		0x0040
+#define RICHACE_SPECIAL_WHO			0x4000
+
+#define RICHACE_VALID_FLAGS (					\
+	RICHACE_FILE_INHERIT_ACE |				\
+	RICHACE_DIRECTORY_INHERIT_ACE |				\
+	RICHACE_NO_PROPAGATE_INHERIT_ACE |			\
+	RICHACE_INHERIT_ONLY_ACE |				\
+	RICHACE_IDENTIFIER_GROUP |				\
+	RICHACE_SPECIAL_WHO)
+
+/* e_mask bitflags */
+#define RICHACE_READ_DATA			0x00000001
+#define RICHACE_LIST_DIRECTORY			0x00000001
+#define RICHACE_WRITE_DATA			0x00000002
+#define RICHACE_ADD_FILE			0x00000002
+#define RICHACE_APPEND_DATA			0x00000004
+#define RICHACE_ADD_SUBDIRECTORY		0x00000004
+#define RICHACE_READ_NAMED_ATTRS		0x00000008
+#define RICHACE_WRITE_NAMED_ATTRS		0x00000010
+#define RICHACE_EXECUTE				0x00000020
+#define RICHACE_DELETE_CHILD			0x00000040
+#define RICHACE_READ_ATTRIBUTES			0x00000080
+#define RICHACE_WRITE_ATTRIBUTES		0x00000100
+#define RICHACE_WRITE_RETENTION			0x00000200
+#define RICHACE_WRITE_RETENTION_HOLD		0x00000400
+#define RICHACE_DELETE				0x00010000
+#define RICHACE_READ_ACL			0x00020000
+#define RICHACE_WRITE_ACL			0x00040000
+#define RICHACE_WRITE_OWNER			0x00080000
+#define RICHACE_SYNCHRONIZE			0x00100000
+
+/* Valid RICHACE_* flags for directories and non-directories */
+#define RICHACE_VALID_MASK (					\
+	RICHACE_READ_DATA | RICHACE_LIST_DIRECTORY |		\
+	RICHACE_WRITE_DATA | RICHACE_ADD_FILE |			\
+	RICHACE_APPEND_DATA | RICHACE_ADD_SUBDIRECTORY |	\
+	RICHACE_READ_NAMED_ATTRS |				\
+	RICHACE_WRITE_NAMED_ATTRS |				\
+	RICHACE_EXECUTE |					\
+	RICHACE_DELETE_CHILD |					\
+	RICHACE_READ_ATTRIBUTES |				\
+	RICHACE_WRITE_ATTRIBUTES |				\
+	RICHACE_WRITE_RETENTION |				\
+	RICHACE_WRITE_RETENTION_HOLD |				\
+	RICHACE_DELETE |					\
+	RICHACE_READ_ACL |					\
+	RICHACE_WRITE_ACL |					\
+	RICHACE_WRITE_OWNER |					\
+	RICHACE_SYNCHRONIZE)
+
+/**
+ * richacl_get  -  grab another reference to a richacl handle
+ */
+static inline struct richacl *
+richacl_get(struct richacl *acl)
+{
+	if (acl)
+		atomic_inc(&acl->a_refcount);
+	return acl;
+}
+
+/**
+ * richacl_put  -  free a richacl handle
+ */
+static inline void
+richacl_put(struct richacl *acl)
+{
+	if (acl && atomic_dec_and_test(&acl->a_refcount))
+		kfree(acl);
+}
+
+/**
+ * richace_is_owner  -  check if @ace is an OWNER@ entry
+ */
+static inline bool
+richace_is_owner(const struct richace *ace)
+{
+	return (ace->e_flags & RICHACE_SPECIAL_WHO) &&
+	       ace->e_id.special == RICHACE_OWNER_SPECIAL_ID;
+}
+
+/**
+ * richace_is_group  -  check if @ace is a GROUP@ entry
+ */
+static inline bool
+richace_is_group(const struct richace *ace)
+{
+	return (ace->e_flags & RICHACE_SPECIAL_WHO) &&
+	       ace->e_id.special == RICHACE_GROUP_SPECIAL_ID;
+}
+
+/**
+ * richace_is_everyone  -  check if @ace is an EVERYONE@ entry
+ */
+static inline bool
+richace_is_everyone(const struct richace *ace)
+{
+	return (ace->e_flags & RICHACE_SPECIAL_WHO) &&
+	       ace->e_id.special == RICHACE_EVERYONE_SPECIAL_ID;
+}
+
+/**
+ * richace_is_unix_id  -  check if @ace applies to a specific uid or gid
+ */
+static inline bool
+richace_is_unix_id(const struct richace *ace)
+{
+	return !(ace->e_flags & RICHACE_SPECIAL_WHO);
+}
+
+/**
+ * richace_is_inherit_only  -  check if @ace is for inheritance only
+ *
+ * ACEs with the %RICHACE_INHERIT_ONLY_ACE flag set have no effect during
+ * permission checking.
+ */
+static inline bool
+richace_is_inherit_only(const struct richace *ace)
+{
+	return ace->e_flags & RICHACE_INHERIT_ONLY_ACE;
+}
+
+/**
+ * richace_is_inheritable  -  check if @ace is inheritable
+ */
+static inline bool
+richace_is_inheritable(const struct richace *ace)
+{
+	return ace->e_flags & (RICHACE_FILE_INHERIT_ACE |
+			       RICHACE_DIRECTORY_INHERIT_ACE);
+}
+
+/**
+ * richace_clear_inheritance_flags  - clear all inheritance flags in @ace
+ */
+static inline void
+richace_clear_inheritance_flags(struct richace *ace)
+{
+	ace->e_flags &= ~(RICHACE_FILE_INHERIT_ACE |
+			  RICHACE_DIRECTORY_INHERIT_ACE |
+			  RICHACE_NO_PROPAGATE_INHERIT_ACE |
+			  RICHACE_INHERIT_ONLY_ACE);
+}
+
+/**
+ * richace_is_allow  -  check if @ace is an %ALLOW type entry
+ */
+static inline bool
+richace_is_allow(const struct richace *ace)
+{
+	return ace->e_type == RICHACE_ACCESS_ALLOWED_ACE_TYPE;
+}
+
+/**
+ * richace_is_deny  -  check if @ace is a %DENY type entry
+ */
+static inline bool
+richace_is_deny(const struct richace *ace)
+{
+	return ace->e_type == RICHACE_ACCESS_DENIED_ACE_TYPE;
+}
+
+/**
+ * richace_is_same_identifier  -  are both identifiers the same?
+ */
+static inline bool
+richace_is_same_identifier(const struct richace *a, const struct richace *b)
+{
+	return !((a->e_flags ^ b->e_flags) &
+		 (RICHACE_SPECIAL_WHO | RICHACE_IDENTIFIER_GROUP)) &&
+	       !memcmp(&a->e_id, &b->e_id, sizeof(a->e_id));
+}
+
+extern struct richacl *richacl_alloc(int, gfp_t);
+extern struct richacl *richacl_clone(const struct richacl *, gfp_t);
+
+#endif /* __RICHACL_H */
-- 
2.1.0