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Subject[PATCH 35/35] Unionfs: Extended Attributes support
Date
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

Extended attribute support.

Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: David Quigley <dquigley@fsl.cs.sunysb.edu>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
---
fs/Kconfig | 9 ++++
fs/unionfs/Makefile | 2 +
fs/unionfs/copyup.c | 75 +++++++++++++++++++++++++++++++
fs/unionfs/inode.c | 12 +++++
fs/unionfs/union.h | 15 ++++++
fs/unionfs/xattr.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 236 insertions(+), 0 deletions(-)

diff --git a/fs/Kconfig b/fs/Kconfig
index 4b31ea4..b8b8e45 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -1567,6 +1567,15 @@ config UNION_FS

See <http://www.unionfs.org> for details

+config UNION_FS_XATTR
+ bool "Unionfs extended attributes"
+ depends on UNION_FS
+ help
+ Extended attributes are name:value pairs associated with inodes by
+ the kernel or by users (see the attr(5) manual page).
+
+ If unsure, say N.
+
endmenu

menu "Network File Systems"
diff --git a/fs/unionfs/Makefile b/fs/unionfs/Makefile
index 25dd78f..7c98325 100644
--- a/fs/unionfs/Makefile
+++ b/fs/unionfs/Makefile
@@ -3,3 +3,5 @@ obj-$(CONFIG_UNION_FS) += unionfs.o
unionfs-y := subr.o dentry.o file.o inode.o main.o super.o \
stale_inode.o branchman.o rdstate.o copyup.o dirhelper.o \
rename.o unlink.o lookup.o commonfops.o dirfops.o sioq.o
+
+unionfs-$(CONFIG_UNION_FS_XATTR) += xattr.o
diff --git a/fs/unionfs/copyup.c b/fs/unionfs/copyup.c
index 0557c02..ec1c649 100644
--- a/fs/unionfs/copyup.c
+++ b/fs/unionfs/copyup.c
@@ -18,6 +18,75 @@

#include "union.h"

+#ifdef CONFIG_UNION_FS_XATTR
+/* copyup all extended attrs for a given dentry */
+static int copyup_xattrs(struct dentry *old_hidden_dentry,
+ struct dentry *new_hidden_dentry)
+{
+ int err = 0;
+ ssize_t list_size = -1;
+ char *name_list = NULL;
+ char *attr_value = NULL;
+ char *name_list_orig = NULL;
+
+ list_size = vfs_listxattr(old_hidden_dentry, NULL, 0);
+
+ if (list_size <= 0) {
+ err = list_size;
+ goto out;
+ }
+
+ name_list = xattr_alloc(list_size + 1, XATTR_LIST_MAX);
+ if (!name_list || IS_ERR(name_list)) {
+ err = PTR_ERR(name_list);
+ goto out;
+ }
+ list_size = vfs_listxattr(old_hidden_dentry, name_list, list_size);
+ attr_value = xattr_alloc(XATTR_SIZE_MAX, XATTR_SIZE_MAX);
+ if (!attr_value || IS_ERR(attr_value)) {
+ err = PTR_ERR(name_list);
+ goto out;
+ }
+ name_list_orig = name_list;
+ while (*name_list) {
+ ssize_t size;
+
+ //We need to lock here since vfs_getxattr doesn't lock for us.
+ mutex_lock(&old_hidden_dentry->d_inode->i_mutex);
+ size = vfs_getxattr(old_hidden_dentry, name_list,
+ attr_value, XATTR_SIZE_MAX);
+ mutex_unlock(&old_hidden_dentry->d_inode->i_mutex);
+ if (size < 0) {
+ err = size;
+ goto out;
+ }
+
+ if (size > XATTR_SIZE_MAX) {
+ err = -E2BIG;
+ goto out;
+ }
+ //We don't need to lock here since vfs_setxattr does it for us.
+ err = vfs_setxattr(new_hidden_dentry, name_list, attr_value,
+ size, 0);
+
+ if (err < 0)
+ goto out;
+ name_list += strlen(name_list) + 1;
+ }
+ out:
+ name_list = name_list_orig;
+
+ if (name_list)
+ xattr_free(name_list, list_size + 1);
+ if (attr_value)
+ xattr_free(attr_value, XATTR_SIZE_MAX);
+ /* It is no big deal if this fails, we just roll with the punches. */
+ if (err == -ENOTSUPP || err == -EOPNOTSUPP)
+ err = 0;
+ return err;
+}
+#endif /* CONFIG_UNION_FS_XATTR */
+
/* Determine the mode based on the copyup flags, and the existing dentry. */
static int copyup_permissions(struct super_block *sb,
struct dentry *old_hidden_dentry,
@@ -343,6 +412,12 @@ int copyup_named_dentry(struct inode *di
if ((err = copyup_permissions(sb, old_hidden_dentry, new_hidden_dentry)))
goto out_unlink;

+#ifdef CONFIG_UNION_FS_XATTR
+ /* Selinux uses extended attributes for permissions. */
+ if ((err = copyup_xattrs(old_hidden_dentry, new_hidden_dentry)))
+ goto out_unlink;
+#endif
+
/* do not allow files getting deleted to be reinterposed */
if (!d_deleted(dentry))
unionfs_reinterpose(dentry);
diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index c7806e9..2e45fb0 100644
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -917,10 +917,22 @@ struct inode_operations unionfs_dir_iops
.rename = unionfs_rename,
.permission = unionfs_permission,
.setattr = unionfs_setattr,
+#ifdef CONFIG_UNION_FS_XATTR
+ .setxattr = unionfs_setxattr,
+ .getxattr = unionfs_getxattr,
+ .removexattr = unionfs_removexattr,
+ .listxattr = unionfs_listxattr,
+#endif
};

struct inode_operations unionfs_main_iops = {
.permission = unionfs_permission,
.setattr = unionfs_setattr,
+#ifdef CONFIG_UNION_FS_XATTR
+ .setxattr = unionfs_setxattr,
+ .getxattr = unionfs_getxattr,
+ .removexattr = unionfs_removexattr,
+ .listxattr = unionfs_listxattr,
+#endif
};

diff --git a/fs/unionfs/union.h b/fs/unionfs/union.h
index ff0b814..58e0cfb 100644
--- a/fs/unionfs/union.h
+++ b/fs/unionfs/union.h
@@ -40,6 +40,7 @@
#include <linux/string.h>
#include <linux/vmalloc.h>
#include <linux/writeback.h>
+#include <linux/xattr.h>
#include <linux/fs_stack.h>

#include <linux/union_fs.h>
@@ -315,6 +316,20 @@ int unionfs_ioctl_queryfile(struct file
/* Verify that a branch is valid. */
int check_branch(struct nameidata *nd);

+#ifdef CONFIG_UNION_FS_XATTR
+/* Extended attribute functions. */
+extern void *xattr_alloc(size_t size, size_t limit);
+extern void xattr_free(void *ptr, size_t size);
+
+extern ssize_t unionfs_getxattr(struct dentry *dentry, const char *name,
+ void *value, size_t size);
+extern int unionfs_removexattr(struct dentry *dentry, const char *name);
+extern ssize_t unionfs_listxattr(struct dentry *dentry, char *list,
+ size_t size);
+extern int unionfs_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags);
+#endif /* CONFIG_UNION_FS_XATTR */
+
/* The root directory is unhashed, but isn't deleted. */
static inline int d_deleted(struct dentry *d)
{
diff --git a/fs/unionfs/xattr.c b/fs/unionfs/xattr.c
new file mode 100644
index 0000000..9f804bf
--- /dev/null
+++ b/fs/unionfs/xattr.c
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2003-2006 Erez Zadok
+ * Copyright (c) 2003-2006 Charles P. Wright
+ * Copyright (c) 2005-2006 Josef 'Jeff' Sipek
+ * Copyright (c) 2005-2006 Junjiro Okajima
+ * Copyright (c) 2005 Arun M. Krishnakumar
+ * Copyright (c) 2004-2006 David P. Quigley
+ * Copyright (c) 2003-2004 Mohammad Nayyer Zubair
+ * Copyright (c) 2003 Puja Gupta
+ * Copyright (c) 2003 Harikesavan Krishnan
+ * Copyright (c) 2003-2006 Stony Brook University
+ * Copyright (c) 2003-2006 The Research Foundation of State University of New York*
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "union.h"
+
+/* This is lifted from fs/xattr.c */
+void *xattr_alloc(size_t size, size_t limit)
+{
+ void *ptr;
+
+ if (size > limit)
+ return ERR_PTR(-E2BIG);
+
+ if (!size) /* size request, no buffer is needed */
+ return NULL;
+ else if (size <= PAGE_SIZE)
+ ptr = kmalloc(size, GFP_KERNEL);
+ else
+ ptr = vmalloc(size);
+ if (!ptr)
+ return ERR_PTR(-ENOMEM);
+ return ptr;
+}
+
+void xattr_free(void *ptr, size_t size)
+{
+ if (!size) /* size request, no buffer was needed */
+ return;
+ else if (size <= PAGE_SIZE)
+ kfree(ptr);
+ else
+ vfree(ptr);
+}
+
+/* BKL held by caller.
+ * dentry->d_inode->i_mutex locked
+ */
+ssize_t unionfs_getxattr(struct dentry * dentry, const char *name, void *value,
+ size_t size)
+{
+ struct dentry *hidden_dentry = NULL;
+ int err = -EOPNOTSUPP;
+
+ lock_dentry(dentry);
+
+ hidden_dentry = unionfs_lower_dentry(dentry);
+
+ err = vfs_getxattr(hidden_dentry, (char*) name, value, size);
+
+ unlock_dentry(dentry);
+ return err;
+}
+
+/* BKL held by caller.
+ * dentry->d_inode->i_mutex locked
+ */
+int unionfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+ size_t size, int flags)
+{
+ struct dentry *hidden_dentry = NULL;
+ int err = -EOPNOTSUPP;
+
+ lock_dentry(dentry);
+ hidden_dentry = unionfs_lower_dentry(dentry);
+
+ err = vfs_setxattr(hidden_dentry, (char*) name, (void*) value, size, flags);
+
+ unlock_dentry(dentry);
+ return err;
+}
+
+/* BKL held by caller.
+ * dentry->d_inode->i_mutex locked
+ */
+int unionfs_removexattr(struct dentry *dentry, const char *name)
+{
+ struct dentry *hidden_dentry = NULL;
+ int err = -EOPNOTSUPP;
+
+ lock_dentry(dentry);
+ hidden_dentry = unionfs_lower_dentry(dentry);
+
+ err = vfs_removexattr(hidden_dentry, (char*) name);
+
+ unlock_dentry(dentry);
+ return err;
+}
+
+/* BKL held by caller.
+ * dentry->d_inode->i_mutex locked
+ */
+ssize_t unionfs_listxattr(struct dentry * dentry, char *list, size_t size)
+{
+ struct dentry *hidden_dentry = NULL;
+ int err = -EOPNOTSUPP;
+ char *encoded_list = NULL;
+
+ lock_dentry(dentry);
+
+ hidden_dentry = unionfs_lower_dentry(dentry);
+
+ encoded_list = list;
+ err = vfs_listxattr(hidden_dentry, encoded_list, size);
+
+ unlock_dentry(dentry);
+ return err;
+}
+
--
1.4.3.3
-
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