[RFC 16/21] richacl: xattr mapping functions

[Andreas Gruenbacher]

Map between "system.richacl" xattrs and the in-kernel representation.

Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
---
 fs/Makefile                   |   2 +-
 fs/richacl_xattr.c            | 131 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/richacl_xattr.h |  47 +++++++++++++++
 3 files changed, 179 insertions(+), 1 deletion(-)
 create mode 100644 fs/richacl_xattr.c
 create mode 100644 include/linux/richacl_xattr.h

diff --git a/fs/Makefile b/fs/Makefile
index bb96ad7..6155cc4 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -48,7 +48,7 @@ obj-$(CONFIG_SYSCTL)		+= drop_caches.o
 
 obj-$(CONFIG_FHANDLE)		+= fhandle.o
 obj-$(CONFIG_FS_RICHACL)	+= richacl.o
-richacl-y			:= richacl_base.o richacl_inode.o
+richacl-y			:= richacl_base.o richacl_inode.o richacl_xattr.o
 
 obj-y				+= quota/
 
diff --git a/fs/richacl_xattr.c b/fs/richacl_xattr.c
new file mode 100644
index 0000000..05e5e97
--- /dev/null
+++ b/fs/richacl_xattr.c
@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2006, 2010  Novell, Inc.
+ * Copyright (C) 2015  Red Hat, Inc.
+ * Written by Andreas Gruenbacher <agruen@xxxxxxxxxx>
+ *
+ * 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/kernel.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/richacl_xattr.h>
+
+MODULE_LICENSE("GPL");
+
+/**
+ * richacl_from_xattr  -  convert a richacl xattr into the in-memory representation
+ */
+struct richacl *
+richacl_from_xattr(const void *value, size_t size)
+{
+	const struct richacl_xattr *xattr_acl = value;
+	const struct richace_xattr *xattr_ace = (void *)(xattr_acl + 1);
+	struct richacl *acl;
+	struct richace *ace;
+	int count;
+
+	if (size < sizeof(struct richacl_xattr) ||
+	    xattr_acl->a_version != ACL4_XATTR_VERSION ||
+	    (xattr_acl->a_flags & ~ACL4_VALID_FLAGS))
+		return ERR_PTR(-EINVAL);
+
+	count = le16_to_cpu(xattr_acl->a_count);
+	if (count > ACL4_XATTR_MAX_COUNT)
+		return ERR_PTR(-EINVAL);
+
+	acl = richacl_alloc(count);
+	if (!acl)
+		return ERR_PTR(-ENOMEM);
+
+	acl->a_flags = xattr_acl->a_flags;
+	acl->a_owner_mask = le32_to_cpu(xattr_acl->a_owner_mask);
+	if (acl->a_owner_mask & ~ACE4_VALID_MASK)
+		goto fail_einval;
+	acl->a_group_mask = le32_to_cpu(xattr_acl->a_group_mask);
+	if (acl->a_group_mask & ~ACE4_VALID_MASK)
+		goto fail_einval;
+	acl->a_other_mask = le32_to_cpu(xattr_acl->a_other_mask);
+	if (acl->a_other_mask & ~ACE4_VALID_MASK)
+		goto fail_einval;
+
+	if (((void *)xattr_ace + count * sizeof(*xattr_ace)) > (value + size))
+		goto fail_einval;
+
+	richacl_for_each_entry(ace, acl) {
+
+		ace->e_type  = le16_to_cpu(xattr_ace->e_type);
+		ace->e_flags = le16_to_cpu(xattr_ace->e_flags);
+		ace->e_mask  = le32_to_cpu(xattr_ace->e_mask);
+		ace->e_id    = le32_to_cpu(xattr_ace->e_id);
+
+		if (ace->e_flags & ~ACE4_VALID_FLAGS)
+			goto fail_einval;
+		if (ace->e_type > ACE4_ACCESS_DENIED_ACE_TYPE ||
+		    (ace->e_mask & ~ACE4_VALID_MASK))
+			goto fail_einval;
+
+		xattr_ace++;
+	}
+
+	return acl;
+
+fail_einval:
+	richacl_put(acl);
+	return ERR_PTR(-EINVAL);
+}
+EXPORT_SYMBOL_GPL(richacl_from_xattr);
+
+/**
+ * richacl_xattr_size  -  compute the size of the xattr representation of @acl
+ */
+size_t
+richacl_xattr_size(const struct richacl *acl)
+{
+	size_t size = sizeof(struct richacl_xattr);
+
+	size += sizeof(struct richace_xattr) * acl->a_count;
+	return size;
+}
+EXPORT_SYMBOL_GPL(richacl_xattr_size);
+
+/**
+ * richacl_to_xattr  -  convert @acl into its xattr representation
+ * @acl:	the richacl to convert
+ * @buffer:	buffer of size richacl_xattr_size(@acl) for the result
+ */
+void
+richacl_to_xattr(const struct richacl *acl, void *buffer)
+{
+	struct richacl_xattr *xattr_acl = buffer;
+	struct richace_xattr *xattr_ace;
+	const struct richace *ace;
+
+	xattr_acl->a_version = ACL4_XATTR_VERSION;
+	xattr_acl->a_flags = acl->a_flags;
+	xattr_acl->a_count = cpu_to_le16(acl->a_count);
+
+	xattr_acl->a_owner_mask = cpu_to_le32(acl->a_owner_mask);
+	xattr_acl->a_group_mask = cpu_to_le32(acl->a_group_mask);
+	xattr_acl->a_other_mask = cpu_to_le32(acl->a_other_mask);
+
+	xattr_ace = (void *)(xattr_acl + 1);
+	richacl_for_each_entry(ace, acl) {
+		xattr_ace->e_type = cpu_to_le16(ace->e_type);
+		xattr_ace->e_flags = cpu_to_le16(ace->e_flags &
+						 ACE4_VALID_FLAGS);
+		xattr_ace->e_mask = cpu_to_le32(ace->e_mask);
+		xattr_ace->e_id = cpu_to_le32(ace->e_id);
+		xattr_ace++;
+	}
+}
+EXPORT_SYMBOL_GPL(richacl_to_xattr);
diff --git a/include/linux/richacl_xattr.h b/include/linux/richacl_xattr.h
new file mode 100644
index 0000000..32ae512
--- /dev/null
+++ b/include/linux/richacl_xattr.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2006, 2010  Novell, Inc.
+ * Copyright (C) 2015  Red Hat, Inc.
+ * Written by Andreas Gruenbacher <agruen@xxxxxxxxxx>
+ *
+ * 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_XATTR_H
+#define __RICHACL_XATTR_H
+
+#include <linux/richacl.h>
+
+#define RICHACL_XATTR "system.richacl"
+
+struct richace_xattr {
+	__le16		e_type;
+	__le16		e_flags;
+	__le32		e_mask;
+	__le32		e_id;
+};
+
+struct richacl_xattr {
+	unsigned char	a_version;
+	unsigned char	a_flags;
+	__le16		a_count;
+	__le32		a_owner_mask;
+	__le32		a_group_mask;
+	__le32		a_other_mask;
+};
+
+#define ACL4_XATTR_VERSION	0
+#define ACL4_XATTR_MAX_COUNT	1024
+
+extern struct richacl *richacl_from_xattr(const void *, size_t);
+extern size_t richacl_xattr_size(const struct richacl *acl);
+extern void richacl_to_xattr(const struct richacl *, void *);
+
+#endif /* __RICHACL_XATTR_H */
-- 
2.1.0

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