[PATCH 5/6] xattr: add new top level nfsd namespace and implement ext3 support

James Morris
2010-03-08T10:46:31Z

Add a new top-level 'nfsd' xattr namespace for use by the NFSv3 server
when storing xattrs provided by clients using the XATTR
protocol.

Also implement filesystem-level support for the new namespace for the
ext3 filesystem for testing.

Signed-off-by: James Morris <jmorris@namei.org>
---
fs/ext3/Makefile | 2 +-
fs/ext3/xattr.c | 2 +
fs/ext3/xattr.h | 2 +
fs/ext3/xattr_nfsd.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/xattr.c | 6 +++-
include/linux/xattr.h | 3 ++
6 files changed, 70 insertions(+), 3 deletions(-)
create mode 100644 fs/ext3/xattr_nfsd.c

diff --git a/fs/ext3/Makefile b/fs/ext3/Makefile
index e77766a..216ca8a 100644
--- a/fs/ext3/Makefile
+++ b/fs/ext3/Makefile
@@ -7,6 +7,6 @@ obj-$(CONFIG_EXT3_FS) += ext3.o
ext3-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
ioctl.o namei.o super.o symlink.o hash.o resize.o ext3_jbd.o

-ext3-$(CONFIG_EXT3_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o
+ext3-$(CONFIG_EXT3_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o xattr_nfsd.o
ext3-$(CONFIG_EXT3_FS_POSIX_ACL) += acl.o
ext3-$(CONFIG_EXT3_FS_SECURITY) += xattr_security.o
diff --git a/fs/ext3/xattr.c b/fs/ext3/xattr.c
index 66895cc..e05ae22 100644
--- a/fs/ext3/xattr.c
+++ b/fs/ext3/xattr.c
@@ -114,6 +114,7 @@ static struct xattr_handler *ext3_xattr_handler_map[] = {
#ifdef CONFIG_EXT3_FS_SECURITY
[EXT3_XATTR_INDEX_SECURITY] = &ext3_xattr_security_handler,
#endif
+ [EXT3_XATTR_INDEX_NFSD] = &ext3_xattr_nfsd_handler,
};

struct xattr_handler *ext3_xattr_handlers[] = {
@@ -126,6 +127,7 @@ struct xattr_handler *ext3_xattr_handlers[] = {
#ifdef CONFIG_EXT3_FS_SECURITY
&ext3_xattr_security_handler,
#endif
+ &ext3_xattr_nfsd_handler,
NULL
};

diff --git a/fs/ext3/xattr.h b/fs/ext3/xattr.h
index 148a4df..e06e90f 100644
--- a/fs/ext3/xattr.h
+++ b/fs/ext3/xattr.h
@@ -21,6 +21,7 @@
#define EXT3_XATTR_INDEX_TRUSTED 4
#define EXT3_XATTR_INDEX_LUSTRE 5
#define EXT3_XATTR_INDEX_SECURITY 6
+#define EXT3_XATTR_INDEX_NFSD 7

struct ext3_xattr_header {
__le32 h_magic; /* magic number for identification */
@@ -63,6 +64,7 @@ extern struct xattr_handler ext3_xattr_trusted_handler;
extern struct xattr_handler ext3_xattr_acl_access_handler;
extern struct xattr_handler ext3_xattr_acl_default_handler;
extern struct xattr_handler ext3_xattr_security_handler;
+extern struct xattr_handler ext3_xattr_nfsd_handler;

extern ssize_t ext3_listxattr(struct dentry *, char *, size_t);

diff --git a/fs/ext3/xattr_nfsd.c b/fs/ext3/xattr_nfsd.c
new file mode 100644
index 0000000..890ccd9
--- /dev/null
+++ b/fs/ext3/xattr_nfsd.c
@@ -0,0 +1,58 @@
+/*
+ * linux/fs/ext3/xattr_nfsd.c
+ * Handler for nfsd extended attributes.
+ *
+ * Copyright (C) 2003 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
+ * Copyright (C) 2010 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ */
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/capability.h>
+#include <linux/fs.h>
+#include <linux/ext3_jbd.h>
+#include <linux/ext3_fs.h>
+#include "xattr.h"
+
+static size_t ext3_xattr_nfsd_list(struct dentry *dentry, char *list,
+ size_t list_size, const char *name,
+ size_t name_len, int type)
+{
+ const size_t prefix_len = XATTR_NFSD_PREFIX_LEN;
+ const size_t total_len = prefix_len + name_len + 1;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return 0;
+
+ if (list && total_len <= list_size) {
+ memcpy(list, XATTR_NFSD_PREFIX, prefix_len);
+ memcpy(list+prefix_len, name, name_len);
+ list[prefix_len + name_len] = '\0';
+ }
+ return total_len;
+}
+
+static int ext3_xattr_nfsd_get(struct dentry *dentry, const char *name,
+ void *buffer, size_t size, int type)
+{
+ if (strcmp(name, "") == 0)
+ return -EINVAL;
+ return ext3_xattr_get(dentry->d_inode, EXT3_XATTR_INDEX_NFSD,
+ name, buffer, size);
+}
+
+static int ext3_xattr_nfsd_set(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags,
+ int type)
+{
+ if (strcmp(name, "") == 0)
+ return -EINVAL;
+ return ext3_xattr_set(dentry->d_inode, EXT3_XATTR_INDEX_NFSD, name,
+ value, size, flags);
+}
+
+struct xattr_handler ext3_xattr_nfsd_handler = {
+ .prefix = XATTR_NFSD_PREFIX,
+ .list = ext3_xattr_nfsd_list,
+ .get = ext3_xattr_nfsd_get,
+ .set = ext3_xattr_nfsd_set,
+};
diff --git a/fs/xattr.c b/fs/xattr.c
index 46f87e8..87b8c8c 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -46,9 +46,11 @@ xattr_permission(struct inode *inode, const char *name, int mask)
return 0;

/*
- * The trusted.* namespace can only be accessed by a privileged user.
+ * The trusted.* and nfsd.* namespaces can only be accessed by a
+ * privileged user.
*/
- if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
+ if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
+ !strncmp(name, XATTR_NFSD_PREFIX, XATTR_NFSD_PREFIX_LEN))
return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);

/* In user.* namespace, only regular files and directories can have
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index fb9b7e6..5b954a2 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -33,6 +33,9 @@
#define XATTR_USER_PREFIX "user."
#define XATTR_USER_PREFIX_LEN (sizeof (XATTR_USER_PREFIX) - 1)

+#define XATTR_NFSD_PREFIX "nfsd."
+#define XATTR_NFSD_PREFIX_LEN (sizeof (XATTR_NFSD_PREFIX) - 1)
+
struct inode;
struct dentry;

--
1.6.3.3