[PATCH v23 06/22] richacl: In-memory representation and helper functions

Andreas Gruenbacher
2016-06-30T13:56:29Z

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>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
---
fs/Makefile | 1 +
fs/richacl.c | 65 ++++++++++++++++
include/linux/richacl.h | 179 +++++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/Kbuild | 1 +
include/uapi/linux/richacl.h | 99 ++++++++++++++++++++++++
5 files changed, 345 insertions(+)
create mode 100644 fs/richacl.c
create mode 100644 include/linux/richacl.h
create mode 100644 include/uapi/linux/richacl.h

diff --git a/fs/Makefile b/fs/Makefile
index 85b6e13..2b3e6f1 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_COREDUMP) += coredump.o
obj-$(CONFIG_SYSCTL) += drop_caches.o

obj-$(CONFIG_FHANDLE) += fhandle.o
+obj-$(CONFIG_FS_RICHACL) += richacl.o

obj-y += quota/

diff --git a/fs/richacl.c b/fs/richacl.c
new file mode 100644
index 0000000..bcc6591
--- /dev/null
+++ b/fs/richacl.c
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2006, 2010 Novell, Inc.
+ * Copyright (C) 2015 Red Hat, Inc.
+ * Written by Andreas Gruenbacher <agruenba@redhat.com>
+ *
+ * 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>
+
+/**
+ * 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;
+}
+
+/**
+ * richace_copy - copy an acl entry
+ */
+void
+richace_copy(struct richace *to, const struct richace *from)
+{
+ memcpy(to, from, sizeof(struct richace));
+}
diff --git a/include/linux/richacl.h b/include/linux/richacl.h
new file mode 100644
index 0000000..edb8480
--- /dev/null
+++ b/include/linux/richacl.h
@@ -0,0 +1,179 @@
+/*
+ * Copyright (C) 2006, 2010 Novell, Inc.
+ * Copyright (C) 2015 Red Hat, Inc.
+ * Written by Andreas Gruenbacher <agruenba@redhat.com>
+ *
+ * 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
+
+#include <uapi/linux/richacl.h>
+
+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--)
+
+/**
+ * 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_user - check if @ace applies to a specific user
+ */
+static inline bool
+richace_is_unix_user(const struct richace *ace)
+{
+ return !(ace->e_flags & RICHACE_SPECIAL_WHO) &&
+ !(ace->e_flags & RICHACE_IDENTIFIER_GROUP);
+}
+
+/**
+ * richace_is_unix_group - check if @ace applies to a specific group
+ */
+static inline bool
+richace_is_unix_group(const struct richace *ace)
+{
+ return !(ace->e_flags & RICHACE_SPECIAL_WHO) &&
+ (ace->e_flags & RICHACE_IDENTIFIER_GROUP);
+}
+
+/**
+ * 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_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);
+extern void richace_copy(struct richace *, const struct richace *);
+
+#endif /* __RICHACL_H */
diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index 8bdae34..abeaa98 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -355,6 +355,7 @@ header-y += reboot.h
header-y += reiserfs_fs.h
header-y += reiserfs_xattr.h
header-y += resource.h
+header-y += richacl.h
header-y += rfkill.h
header-y += rio_mport_cdev.h
header-y += romfs_fs.h
diff --git a/include/uapi/linux/richacl.h b/include/uapi/linux/richacl.h
new file mode 100644
index 0000000..08856f8
--- /dev/null
+++ b/include/uapi/linux/richacl.h
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2006, 2010 Novell, Inc.
+ * Copyright (C) 2015 Red Hat, Inc.
+ * Written by Andreas Gruenbacher <agruenba@redhat.com>
+ *
+ * This file is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This file 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
+ * Lesser General Public License for more details.
+ */
+
+#ifndef __UAPI_RICHACL_H
+#define __UAPI_RICHACL_H
+
+/* a_flags values */
+#define RICHACL_WRITE_THROUGH 0x40
+#define RICHACL_MASKED 0x80
+
+/* 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
+
+/* 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
+
+/* e_id values */
+#define RICHACE_OWNER_SPECIAL_ID 0
+#define RICHACE_GROUP_SPECIAL_ID 1
+#define RICHACE_EVERYONE_SPECIAL_ID 2
+
+#define RICHACL_VALID_FLAGS ( \
+ RICHACL_WRITE_THROUGH | \
+ RICHACL_MASKED )
+
+#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 )
+
+#define RICHACE_INHERITANCE_FLAGS ( \
+ RICHACE_FILE_INHERIT_ACE | \
+ RICHACE_DIRECTORY_INHERIT_ACE | \
+ RICHACE_NO_PROPAGATE_INHERIT_ACE | \
+ RICHACE_INHERIT_ONLY_ACE )
+
+/* 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 )
+
+#endif /* __UAPI_RICHACL_H */
--
2.5.5