fs/9p: Implement POSIX ACL permission checking function
The ACL value is fetched as a part of inode initialization
from the server and the permission checking function use the
cached value of the ACL
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/fs/9p/acl.c b/fs/9p/acl.c
new file mode 100644
index 0000000..a8c0136
--- /dev/null
+++ b/fs/9p/acl.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright IBM Corporation, 2010
+ * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <net/9p/9p.h>
+#include <net/9p/client.h>
+#include <linux/slab.h>
+#include <linux/posix_acl_xattr.h>
+#include "xattr.h"
+#include "acl.h"
+
+static struct posix_acl *__v9fs_get_acl(struct p9_fid *fid, char *name)
+{
+ ssize_t size;
+ void *value = NULL;
+ struct posix_acl *acl = NULL;;
+
+ size = v9fs_fid_xattr_get(fid, name, NULL, 0);
+ if (size > 0) {
+ value = kzalloc(size, GFP_NOFS);
+ if (!value)
+ return ERR_PTR(-ENOMEM);
+ size = v9fs_fid_xattr_get(fid, name, value, size);
+ if (size > 0) {
+ acl = posix_acl_from_xattr(value, size);
+ if (IS_ERR(acl))
+ goto err_out;
+ }
+ } else if (size == -ENODATA || size == 0 ||
+ size == -ENOSYS || size == -EOPNOTSUPP) {
+ acl = NULL;
+ } else
+ acl = ERR_PTR(-EIO);
+
+err_out:
+ kfree(value);
+ return acl;
+}
+
+int v9fs_get_acl(struct inode *inode, struct p9_fid *fid)
+{
+ int retval = 0;
+ struct posix_acl *pacl, *dacl;
+
+ /* get the default/access acl values and cache them */
+ dacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_DEFAULT);
+ pacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_ACCESS);
+
+ if (!IS_ERR(dacl) && !IS_ERR(pacl)) {
+ set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
+ set_cached_acl(inode, ACL_TYPE_ACCESS, pacl);
+ posix_acl_release(dacl);
+ posix_acl_release(pacl);
+ } else
+ retval = -EIO;
+
+ return retval;
+}
+
+static struct posix_acl *v9fs_get_cached_acl(struct inode *inode, int type)
+{
+ struct posix_acl *acl;
+ /*
+ * 9p Always cache the acl value when
+ * instantiating the inode (v9fs_inode_from_fid)
+ */
+ acl = get_cached_acl(inode, type);
+ BUG_ON(acl == ACL_NOT_CACHED);
+ return acl;
+}
+
+int v9fs_check_acl(struct inode *inode, int mask)
+{
+ struct posix_acl *acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
+
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ if (acl) {
+ int error = posix_acl_permission(inode, acl, mask);
+ posix_acl_release(acl);
+ return error;
+ }
+ return -EAGAIN;
+}