Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y

1 files changed, 666 insertions, 0 deletions

diff --git a/fs/xattr.c b/fs/xattr.c
new file mode 100644
index 0000000..086db06
--- /dev/null
+++ b/fs/xattr.c
@@ -0,0 +1,666 @@
+/*
+  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/file.h>
+#include <linux/xattr.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/module.h>
+#include <linux/fsnotify.h>
+#include <linux/audit.h>
+#include <asm/uaccess.h>
+
+
+/*
+ * Check permissions for extended attribute access.  This is a bit complicated
+ * because different namespaces have very different rules.
+ */
+static int
+xattr_permission(struct inode *inode, const char *name, int mask)
+{
+	/*
+	 * We can never set or remove an extended attribute on a read-only
+	 * filesystem  or on an immutable / append-only inode.
+	 */
+	if (mask & MAY_WRITE) {
+		if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+			return -EPERM;
+	}
+
+	/*
+	 * No restriction for security.* and system.* from the VFS.  Decision
+	 * on these is left to the underlying filesystem / security module.
+	 */
+	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
+	    !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return 0;
+
+	/*
+	 * The trusted.* namespace can only be accessed by a privileged user.
+	 */
+	if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
+		return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
+
+	/* In user.* namespace, only regular files and directories can have
+	 * extended attributes. For sticky directories, only the owner and
+	 * privileged user can write attributes.
+	 */
+	if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
+		if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
+			return -EPERM;
+		if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
+		    (mask & MAY_WRITE) && !is_owner_or_cap(inode))
+			return -EPERM;
+	}
+
+	return inode_permission(inode, mask);
+}
+
+int
+vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	mutex_lock(&inode->i_mutex);
+	error = security_inode_setxattr(dentry, name, value, size, flags);
+	if (error)
+		goto out;
+	error = -EOPNOTSUPP;
+	if (inode->i_op->setxattr) {
+		error = inode->i_op->setxattr(dentry, name, value, size, flags);
+		if (!error) {
+			fsnotify_xattr(dentry);
+			security_inode_post_setxattr(dentry, name, value,
+						     size, flags);
+		}
+	} else if (!strncmp(name, XATTR_SECURITY_PREFIX,
+				XATTR_SECURITY_PREFIX_LEN)) {
+		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+		error = security_inode_setsecurity(inode, suffix, value,
+						   size, flags);
+		if (!error)
+			fsnotify_xattr(dentry);
+	}
+out:
+	mutex_unlock(&inode->i_mutex);
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_setxattr);
+
+ssize_t
+xattr_getsecurity(struct inode *inode, const char *name, void *value,
+			size_t size)
+{
+	void *buffer = NULL;
+	ssize_t len;
+
+	if (!value || !size) {
+		len = security_inode_getsecurity(inode, name, &buffer, false);
+		goto out_noalloc;
+	}
+
+	len = security_inode_getsecurity(inode, name, &buffer, true);
+	if (len < 0)
+		return len;
+	if (size < len) {
+		len = -ERANGE;
+		goto out;
+	}
+	memcpy(value, buffer, len);
+out:
+	security_release_secctx(buffer, len);
+out_noalloc:
+	return len;
+}
+EXPORT_SYMBOL_GPL(xattr_getsecurity);
+
+ssize_t
+vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(inode, name, MAY_READ);
+	if (error)
+		return error;
+
+	error = security_inode_getxattr(dentry, name);
+	if (error)
+		return error;
+
+	if (!strncmp(name, XATTR_SECURITY_PREFIX,
+				XATTR_SECURITY_PREFIX_LEN)) {
+		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+		int ret = xattr_getsecurity(inode, suffix, value, size);
+		/*
+		 * Only overwrite the return value if a security module
+		 * is actually active.
+		 */
+		if (ret == -EOPNOTSUPP)
+			goto nolsm;
+		return ret;
+	}
+nolsm:
+	if (inode->i_op->getxattr)
+		error = inode->i_op->getxattr(dentry, name, value, size);
+	else
+		error = -EOPNOTSUPP;
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_getxattr);
+
+ssize_t
+vfs_listxattr(struct dentry *d, char *list, size_t size)
+{
+	ssize_t error;
+
+	error = security_inode_listxattr(d);
+	if (error)
+		return error;
+	error = -EOPNOTSUPP;
+	if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
+		error = d->d_inode->i_op->listxattr(d, list, size);
+	} else {
+		error = security_inode_listsecurity(d->d_inode, list, size);
+		if (size && error > size)
+			error = -ERANGE;
+	}
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_listxattr);
+
+int
+vfs_removexattr(struct dentry *dentry, const char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	if (!inode->i_op->removexattr)
+		return -EOPNOTSUPP;
+
+	error = xattr_permission(inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	error = security_inode_removexattr(dentry, name);
+	if (error)
+		return error;
+
+	mutex_lock(&inode->i_mutex);
+	error = inode->i_op->removexattr(dentry, name);
+	mutex_unlock(&inode->i_mutex);
+
+	if (!error)
+		fsnotify_xattr(dentry);
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_removexattr);
+
+
+/*
+ * Extended attribute SET operations
+ */
+static long
+setxattr(struct dentry *d, const char __user *name, const 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 = vfs_setxattr(d, kname, kvalue, size, flags);
+	kfree(kvalue);
+	return error;
+}
+
+SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
+		const char __user *, name, const void __user *, value,
+		size_t, size, int, flags)
+{
+	struct path path;
+	int error;
+
+	error = user_path(pathname, &path);
+	if (error)
+		return error;
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = setxattr(path.dentry, name, value, size, flags);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
+	return error;
+}
+
+SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
+		const char __user *, name, const void __user *, value,
+		size_t, size, int, flags)
+{
+	struct path path;
+	int error;
+
+	error = user_lpath(pathname, &path);
+	if (error)
+		return error;
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = setxattr(path.dentry, name, value, size, flags);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
+	return error;
+}
+
+SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
+		const void __user *,value, size_t, size, int, flags)
+{
+	struct file *f;
+	struct dentry *dentry;
+	int error = -EBADF;
+
+	f = fget(fd);
+	if (!f)
+		return error;
+	dentry = f->f_path.dentry;
+	audit_inode(NULL, dentry);
+	error = mnt_want_write(f->f_path.mnt);
+	if (!error) {
+		error = setxattr(dentry, name, value, size, flags);
+		mnt_drop_write(f->f_path.mnt);
+	}
+	fput(f);
+	return error;
+}
+
+/*
+ * Extended attribute GET operations
+ */
+static ssize_t
+getxattr(struct dentry *d, const 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 = kzalloc(size, GFP_KERNEL);
+		if (!kvalue)
+			return -ENOMEM;
+	}
+
+	error = vfs_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;
+	}
+	kfree(kvalue);
+	return error;
+}
+
+SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
+		const char __user *, name, void __user *, value, size_t, size)
+{
+	struct path path;
+	ssize_t error;
+
+	error = user_path(pathname, &path);
+	if (error)
+		return error;
+	error = getxattr(path.dentry, name, value, size);
+	path_put(&path);
+	return error;
+}
+
+SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
+		const char __user *, name, void __user *, value, size_t, size)
+{
+	struct path path;
+	ssize_t error;
+
+	error = user_lpath(pathname, &path);
+	if (error)
+		return error;
+	error = getxattr(path.dentry, name, value, size);
+	path_put(&path);
+	return error;
+}
+
+SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
+		void __user *, value, size_t, size)
+{
+	struct file *f;
+	ssize_t error = -EBADF;
+
+	f = fget(fd);
+	if (!f)
+		return error;
+	audit_inode(NULL, f->f_path.dentry);
+	error = getxattr(f->f_path.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 = vfs_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;
+	}
+	kfree(klist);
+	return error;
+}
+
+SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
+		size_t, size)
+{
+	struct path path;
+	ssize_t error;
+
+	error = user_path(pathname, &path);
+	if (error)
+		return error;
+	error = listxattr(path.dentry, list, size);
+	path_put(&path);
+	return error;
+}
+
+SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
+		size_t, size)
+{
+	struct path path;
+	ssize_t error;
+
+	error = user_lpath(pathname, &path);
+	if (error)
+		return error;
+	error = listxattr(path.dentry, list, size);
+	path_put(&path);
+	return error;
+}
+
+SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
+{
+	struct file *f;
+	ssize_t error = -EBADF;
+
+	f = fget(fd);
+	if (!f)
+		return error;
+	audit_inode(NULL, f->f_path.dentry);
+	error = listxattr(f->f_path.dentry, list, size);
+	fput(f);
+	return error;
+}
+
+/*
+ * Extended attribute REMOVE operations
+ */
+static long
+removexattr(struct dentry *d, const 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;
+
+	return vfs_removexattr(d, kname);
+}
+
+SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
+		const char __user *, name)
+{
+	struct path path;
+	int error;
+
+	error = user_path(pathname, &path);
+	if (error)
+		return error;
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = removexattr(path.dentry, name);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
+	return error;
+}
+
+SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
+		const char __user *, name)
+{
+	struct path path;
+	int error;
+
+	error = user_lpath(pathname, &path);
+	if (error)
+		return error;
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = removexattr(path.dentry, name);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
+	return error;
+}
+
+SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
+{
+	struct file *f;
+	struct dentry *dentry;
+	int error = -EBADF;
+
+	f = fget(fd);
+	if (!f)
+		return error;
+	dentry = f->f_path.dentry;
+	audit_inode(NULL, dentry);
+	error = mnt_want_write(f->f_path.mnt);
+	if (!error) {
+		error = removexattr(dentry, name);
+		mnt_drop_write(f->f_path.mnt);
+	}
+	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);