[PATCH -V2 13/16] richacl: xattr mapping functions

Aneesh Kumar K.V
2010-07-02T18:45:19Z

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

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
fs/Makefile | 2 +-
fs/richacl_xattr.c | 156 +++++++++++++++++++++++++++++++++++++++++
include/linux/richacl_xattr.h | 47 ++++++++++++
3 files changed, 204 insertions(+), 1 deletions(-)
create mode 100644 fs/richacl_xattr.c
create mode 100644 include/linux/richacl_xattr.h

diff --git a/fs/Makefile b/fs/Makefile
index b38cfc7..35ac29d 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -52,7 +52,7 @@ obj-$(CONFIG_NFS_COMMON) += nfs_common/
obj-$(CONFIG_GENERIC_ACL) += generic_acl.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..1f6e3f2
--- /dev/null
+++ b/fs/richacl_xattr.c
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2006, 2010 Novell, Inc.
+ * Written by Andreas Gruenbacher <agruen@suse.de>
+ *
+ * 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;
+
+ richacl_for_each_entry(ace, acl) {
+ const char *who = (void *)(xattr_ace + 1), *end;
+ ssize_t used = (void *)who - value;
+
+ if (used > size)
+ goto fail_einval;
+ end = memchr(who, 0, size - used);
+ if (!end)
+ goto fail_einval;
+
+ 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->u.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;
+
+ if (who == end) {
+ if (ace->u.e_id == -1)
+ goto fail_einval; /* uid/gid needed */
+ } else if (richace_set_who(ace, who))
+ goto fail_einval;
+
+ xattr_ace = (void *)who + ALIGN(end - who + 1, 4);
+ }
+
+ 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);
+ const struct richace *ace;
+
+ richacl_for_each_entry(ace, acl) {
+ size += sizeof(struct richace_xattr) +
+ (richace_is_unix_id(ace) ? 4 :
+ ALIGN(strlen(ace->u.e_who) + 1, 4));
+ }
+ 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);
+ if (richace_is_unix_id(ace)) {
+ xattr_ace->e_id = cpu_to_le32(ace->u.e_id);
+ memset(xattr_ace->e_who, 0, 4);
+ xattr_ace = (void *)xattr_ace->e_who + 4;
+ } else {
+ int sz = ALIGN(strlen(ace->u.e_who) + 1, 4);
+
+ xattr_ace->e_id = cpu_to_le32(-1);
+ memset(xattr_ace->e_who + sz - 4, 0, 4);
+ strcpy(xattr_ace->e_who, ace->u.e_who);
+ xattr_ace = (void *)xattr_ace->e_who + sz;
+ }
+ }
+}
+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..e038a7c
--- /dev/null
+++ b/include/linux/richacl_xattr.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2006, 2010 Novell, Inc.
+ * Written by Andreas Gruenbacher <agruen@suse.de>
+ *
+ * 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;
+ char e_who[0];
+};
+
+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 */
--
1.7.2.rc1