1 files changed, 480 insertions, 0 deletions
diff --git a/fs/xattr.c b/fs/xattr.c
new file mode 100644
index 000000000000..93dee70a1dbe
--- /dev/null
+++ b/fs/xattr.c
@@ -0,0 +1,480 @@
+/*
+  File: fs/xattr.c
+
+  Extended attribute handling.
+
+  Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
+  Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
+  Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ */
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.h>
+#include <linux/file.h>
+#include <linux/xattr.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/module.h>
+#include <asm/uaccess.h>
+
+/*
+ * Extended attribute SET operations
+ */
+static long
+setxattr(struct dentry *d, char __user *name, void __user *value,
+	 size_t size, int flags)
+{
+	int error;
+	void *kvalue = NULL;
+	char kname[XATTR_NAME_MAX + 1];
+
+	if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
+		return -EINVAL;
+
+	error = strncpy_from_user(kname, name, sizeof(kname));
+	if (error == 0 || error == sizeof(kname))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
+
+	if (size) {
+		if (size > XATTR_SIZE_MAX)
+			return -E2BIG;
+		kvalue = kmalloc(size, GFP_KERNEL);
+		if (!kvalue)
+			return -ENOMEM;
+		if (copy_from_user(kvalue, value, size)) {
+			kfree(kvalue);
+			return -EFAULT;
+		}
+	}
+
+	error = -EOPNOTSUPP;
+	if (d->d_inode->i_op && d->d_inode->i_op->setxattr) {
+		down(&d->d_inode->i_sem);
+		error = security_inode_setxattr(d, kname, kvalue, size, flags);
+		if (error)
+			goto out;
+		error = d->d_inode->i_op->setxattr(d, kname, kvalue, size, flags);
+		if (!error)
+			security_inode_post_setxattr(d, kname, kvalue, size, flags);
+out:
+		up(&d->d_inode->i_sem);
+	}
+	if (kvalue)
+		kfree(kvalue);
+	return error;
+}
+
+asmlinkage long
+sys_setxattr(char __user *path, char __user *name, void __user *value,
+	     size_t size, int flags)
+{
+	struct nameidata nd;
+	int error;
+
+	error = user_path_walk(path, &nd);
+	if (error)
+		return error;
+	error = setxattr(nd.dentry, name, value, size, flags);
+	path_release(&nd);
+	return error;
+}
+
+asmlinkage long
+sys_lsetxattr(char __user *path, char __user *name, void __user *value,
+	      size_t size, int flags)
+{
+	struct nameidata nd;
+	int error;
+
+	error = user_path_walk_link(path, &nd);
+	if (error)
+		return error;
+	error = setxattr(nd.dentry, name, value, size, flags);
+	path_release(&nd);
+	return error;
+}
+
+asmlinkage long
+sys_fsetxattr(int fd, char __user *name, void __user *value,
+	      size_t size, int flags)
+{
+	struct file *f;
+	int error = -EBADF;
+
+	f = fget(fd);
+	if (!f)
+		return error;
+	error = setxattr(f->f_dentry, name, value, size, flags);
+	fput(f);
+	return error;
+}
+
+/*
+ * Extended attribute GET operations
+ */
+static ssize_t
+getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
+{
+	ssize_t error;
+	void *kvalue = NULL;
+	char kname[XATTR_NAME_MAX + 1];
+
+	error = strncpy_from_user(kname, name, sizeof(kname));
+	if (error == 0 || error == sizeof(kname))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
+
+	if (size) {
+		if (size > XATTR_SIZE_MAX)
+			size = XATTR_SIZE_MAX;
+		kvalue = kmalloc(size, GFP_KERNEL);
+		if (!kvalue)
+			return -ENOMEM;
+	}
+
+	error = -EOPNOTSUPP;
+	if (d->d_inode->i_op && d->d_inode->i_op->getxattr) {
+		error = security_inode_getxattr(d, kname);
+		if (error)
+			goto out;
+		error = d->d_inode->i_op->getxattr(d, kname, kvalue, size);
+		if (error > 0) {
+			if (size && copy_to_user(value, kvalue, error))
+				error = -EFAULT;
+		} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
+			/* The file system tried to returned a value bigger
+			   than XATTR_SIZE_MAX bytes. Not possible. */
+			error = -E2BIG;
+		}
+	}
+out:
+	if (kvalue)
+		kfree(kvalue);
+	return error;
+}
+
+asmlinkage ssize_t
+sys_getxattr(char __user *path, char __user *name, void __user *value,
+	     size_t size)
+{
+	struct nameidata nd;
+	ssize_t error;
+
+	error = user_path_walk(path, &nd);
+	if (error)
+		return error;
+	error = getxattr(nd.dentry, name, value, size);
+	path_release(&nd);
+	return error;
+}
+
+asmlinkage ssize_t
+sys_lgetxattr(char __user *path, char __user *name, void __user *value,
+	      size_t size)
+{
+	struct nameidata nd;
+	ssize_t error;
+
+	error = user_path_walk_link(path, &nd);
+	if (error)
+		return error;
+	error = getxattr(nd.dentry, name, value, size);
+	path_release(&nd);
+	return error;
+}
+
+asmlinkage ssize_t
+sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size)
+{
+	struct file *f;
+	ssize_t error = -EBADF;
+
+	f = fget(fd);
+	if (!f)
+		return error;
+	error = getxattr(f->f_dentry, name, value, size);
+	fput(f);
+	return error;
+}
+
+/*
+ * Extended attribute LIST operations
+ */
+static ssize_t
+listxattr(struct dentry *d, char __user *list, size_t size)
+{
+	ssize_t error;
+	char *klist = NULL;
+
+	if (size) {
+		if (size > XATTR_LIST_MAX)
+			size = XATTR_LIST_MAX;
+		klist = kmalloc(size, GFP_KERNEL);
+		if (!klist)
+			return -ENOMEM;
+	}
+
+	error = -EOPNOTSUPP;
+	if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
+		error = security_inode_listxattr(d);
+		if (error)
+			goto out;
+		error = d->d_inode->i_op->listxattr(d, klist, size);
+		if (error > 0) {
+			if (size && copy_to_user(list, klist, error))
+				error = -EFAULT;
+		} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
+			/* The file system tried to returned a list bigger
+			   than XATTR_LIST_MAX bytes. Not possible. */
+			error = -E2BIG;
+		}
+	}
+out:
+	if (klist)
+		kfree(klist);
+	return error;
+}
+
+asmlinkage ssize_t
+sys_listxattr(char __user *path, char __user *list, size_t size)
+{
+	struct nameidata nd;
+	ssize_t error;
+
+	error = user_path_walk(path, &nd);
+	if (error)
+		return error;
+	error = listxattr(nd.dentry, list, size);
+	path_release(&nd);
+	return error;
+}
+
+asmlinkage ssize_t
+sys_llistxattr(char __user *path, char __user *list, size_t size)
+{
+	struct nameidata nd;
+	ssize_t error;
+
+	error = user_path_walk_link(path, &nd);
+	if (error)
+		return error;
+	error = listxattr(nd.dentry, list, size);
+	path_release(&nd);
+	return error;
+}
+
+asmlinkage ssize_t
+sys_flistxattr(int fd, char __user *list, size_t size)
+{
+	struct file *f;
+	ssize_t error = -EBADF;
+
+	f = fget(fd);
+	if (!f)
+		return error;
+	error = listxattr(f->f_dentry, list, size);
+	fput(f);
+	return error;
+}
+
+/*
+ * Extended attribute REMOVE operations
+ */
+static long
+removexattr(struct dentry *d, char __user *name)
+{
+	int error;
+	char kname[XATTR_NAME_MAX + 1];
+
+	error = strncpy_from_user(kname, name, sizeof(kname));
+	if (error == 0 || error == sizeof(kname))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
+
+	error = -EOPNOTSUPP;
+	if (d->d_inode->i_op && d->d_inode->i_op->removexattr) {
+		error = security_inode_removexattr(d, kname);
+		if (error)
+			goto out;
+		down(&d->d_inode->i_sem);
+		error = d->d_inode->i_op->removexattr(d, kname);
+		up(&d->d_inode->i_sem);
+	}
+out:
+	return error;
+}
+
+asmlinkage long
+sys_removexattr(char __user *path, char __user *name)
+{
+	struct nameidata nd;
+	int error;
+
+	error = user_path_walk(path, &nd);
+	if (error)
+		return error;
+	error = removexattr(nd.dentry, name);
+	path_release(&nd);
+	return error;
+}
+
+asmlinkage long
+sys_lremovexattr(char __user *path, char __user *name)
+{
+	struct nameidata nd;
+	int error;
+
+	error = user_path_walk_link(path, &nd);
+	if (error)
+		return error;
+	error = removexattr(nd.dentry, name);
+	path_release(&nd);
+	return error;
+}
+
+asmlinkage long
+sys_fremovexattr(int fd, char __user *name)
+{
+	struct file *f;
+	int error = -EBADF;
+
+	f = fget(fd);
+	if (!f)
+		return error;
+	error = removexattr(f->f_dentry, name);
+	fput(f);
+	return error;
+}
+
+
+static const char *
+strcmp_prefix(const char *a, const char *a_prefix)
+{
+	while (*a_prefix && *a == *a_prefix) {
+		a++;
+		a_prefix++;
+	}
+	return *a_prefix ? NULL : a;
+}
+
+/*
+ * In order to implement different sets of xattr operations for each xattr
+ * prefix with the generic xattr API, a filesystem should create a
+ * null-terminated array of struct xattr_handler (one for each prefix) and
+ * hang a pointer to it off of the s_xattr field of the superblock.
+ *
+ * The generic_fooxattr() functions will use this list to dispatch xattr
+ * operations to the correct xattr_handler.
+ */
+#define for_each_xattr_handler(handlers, handler)		\
+		for ((handler) = *(handlers)++;			\
+			(handler) != NULL;			\
+			(handler) = *(handlers)++)
+
+/*
+ * Find the xattr_handler with the matching prefix.
+ */
+static struct xattr_handler *
+xattr_resolve_name(struct xattr_handler **handlers, const char **name)
+{
+	struct xattr_handler *handler;
+
+	if (!*name)
+		return NULL;
+
+	for_each_xattr_handler(handlers, handler) {
+		const char *n = strcmp_prefix(*name, handler->prefix);
+		if (n) {
+			*name = n;
+			break;
+		}
+	}
+	return handler;
+}
+
+/*
+ * Find the handler for the prefix and dispatch its get() operation.
+ */
+ssize_t
+generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
+{
+	struct xattr_handler *handler;
+	struct inode *inode = dentry->d_inode;
+
+	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
+	if (!handler)
+		return -EOPNOTSUPP;
+	return handler->get(inode, name, buffer, size);
+}
+
+/*
+ * Combine the results of the list() operation from every xattr_handler in the
+ * list.
+ */
+ssize_t
+generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
+{
+	struct inode *inode = dentry->d_inode;
+	struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr;
+	unsigned int size = 0;
+
+	if (!buffer) {
+		for_each_xattr_handler(handlers, handler)
+			size += handler->list(inode, NULL, 0, NULL, 0);
+	} else {
+		char *buf = buffer;
+
+		for_each_xattr_handler(handlers, handler) {
+			size = handler->list(inode, buf, buffer_size, NULL, 0);
+			if (size > buffer_size)
+				return -ERANGE;
+			buf += size;
+			buffer_size -= size;
+		}
+		size = buf - buffer;
+	}
+	return size;
+}
+
+/*
+ * Find the handler for the prefix and dispatch its set() operation.
+ */
+int
+generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
+{
+	struct xattr_handler *handler;
+	struct inode *inode = dentry->d_inode;
+
+	if (size == 0)
+		value = "";  /* empty EA, do not remove */
+	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
+	if (!handler)
+		return -EOPNOTSUPP;
+	return handler->set(inode, name, value, size, flags);
+}
+
+/*
+ * Find the handler for the prefix and dispatch its set() operation to remove
+ * any associated extended attribute.
+ */
+int
+generic_removexattr(struct dentry *dentry, const char *name)
+{
+	struct xattr_handler *handler;
+	struct inode *inode = dentry->d_inode;
+
+	handler = xattr_resolve_name(inode->i_sb->s_xattr, &name);
+	if (!handler)
+		return -EOPNOTSUPP;
+	return handler->set(inode, name, NULL, 0, XATTR_REPLACE);
+}
+
+EXPORT_SYMBOL(generic_getxattr);
+EXPORT_SYMBOL(generic_listxattr);
+EXPORT_SYMBOL(generic_setxattr);
+EXPORT_SYMBOL(generic_removexattr);