Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1411 insertions, 0 deletions

diff --git a/fs/xattr.c b/fs/xattr.c
new file mode 100644
index 0000000000..efd4736bc9
--- /dev/null
+++ b/fs/xattr.c
@@ -0,0 +1,1411 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+  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/filelock.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/evm.h>
+#include <linux/syscalls.h>
+#include <linux/export.h>
+#include <linux/fsnotify.h>
+#include <linux/audit.h>
+#include <linux/vmalloc.h>
+#include <linux/posix_acl_xattr.h>
+
+#include <linux/uaccess.h>
+
+#include "internal.h"
+
+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, 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.
+ */
+#define for_each_xattr_handler(handlers, handler)		\
+	if (handlers)						\
+		for ((handler) = *(handlers)++;			\
+			(handler) != NULL;			\
+			(handler) = *(handlers)++)
+
+/*
+ * Find the xattr_handler with the matching prefix.
+ */
+static const struct xattr_handler *
+xattr_resolve_name(struct inode *inode, const char **name)
+{
+	const struct xattr_handler **handlers = inode->i_sb->s_xattr;
+	const struct xattr_handler *handler;
+
+	if (!(inode->i_opflags & IOP_XATTR)) {
+		if (unlikely(is_bad_inode(inode)))
+			return ERR_PTR(-EIO);
+		return ERR_PTR(-EOPNOTSUPP);
+	}
+	for_each_xattr_handler(handlers, handler) {
+		const char *n;
+
+		n = strcmp_prefix(*name, xattr_prefix(handler));
+		if (n) {
+			if (!handler->prefix ^ !*n) {
+				if (*n)
+					continue;
+				return ERR_PTR(-EINVAL);
+			}
+			*name = n;
+			return handler;
+		}
+	}
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+/**
+ * may_write_xattr - check whether inode allows writing xattr
+ * @idmap: idmap of the mount the inode was found from
+ * @inode: the inode on which to set an xattr
+ *
+ * Check whether the inode allows writing xattrs. Specifically, we can never
+ * set or remove an extended attribute on a read-only filesystem  or on an
+ * immutable / append-only inode.
+ *
+ * We also need to ensure that the inode has a mapping in the mount to
+ * not risk writing back invalid i_{g,u}id values.
+ *
+ * Return: On success zero is returned. On error a negative errno is returned.
+ */
+int may_write_xattr(struct mnt_idmap *idmap, struct inode *inode)
+{
+	if (IS_IMMUTABLE(inode))
+		return -EPERM;
+	if (IS_APPEND(inode))
+		return -EPERM;
+	if (HAS_UNMAPPED_ID(idmap, inode))
+		return -EPERM;
+	return 0;
+}
+
+/*
+ * Check permissions for extended attribute access.  This is a bit complicated
+ * because different namespaces have very different rules.
+ */
+static int
+xattr_permission(struct mnt_idmap *idmap, struct inode *inode,
+		 const char *name, int mask)
+{
+	if (mask & MAY_WRITE) {
+		int ret;
+
+		ret = may_write_xattr(idmap, inode);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * 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 privileged users.
+	 */
+	if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
+		if (!capable(CAP_SYS_ADMIN))
+			return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
+		return 0;
+	}
+
+	/*
+	 * In the user.* namespace, only regular files and directories can have
+	 * extended attributes. For sticky directories, only the owner and
+	 * privileged users 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 (mask & MAY_WRITE) ? -EPERM : -ENODATA;
+		if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
+		    (mask & MAY_WRITE) &&
+		    !inode_owner_or_capable(idmap, inode))
+			return -EPERM;
+	}
+
+	return inode_permission(idmap, inode, mask);
+}
+
+/*
+ * Look for any handler that deals with the specified namespace.
+ */
+int
+xattr_supports_user_prefix(struct inode *inode)
+{
+	const struct xattr_handler **handlers = inode->i_sb->s_xattr;
+	const struct xattr_handler *handler;
+
+	if (!(inode->i_opflags & IOP_XATTR)) {
+		if (unlikely(is_bad_inode(inode)))
+			return -EIO;
+		return -EOPNOTSUPP;
+	}
+
+	for_each_xattr_handler(handlers, handler) {
+		if (!strncmp(xattr_prefix(handler), XATTR_USER_PREFIX,
+			     XATTR_USER_PREFIX_LEN))
+			return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL(xattr_supports_user_prefix);
+
+int
+__vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
+	       struct inode *inode, const char *name, const void *value,
+	       size_t size, int flags)
+{
+	const struct xattr_handler *handler;
+
+	if (is_posix_acl_xattr(name))
+		return -EOPNOTSUPP;
+
+	handler = xattr_resolve_name(inode, &name);
+	if (IS_ERR(handler))
+		return PTR_ERR(handler);
+	if (!handler->set)
+		return -EOPNOTSUPP;
+	if (size == 0)
+		value = "";  /* empty EA, do not remove */
+	return handler->set(handler, idmap, dentry, inode, name, value,
+			    size, flags);
+}
+EXPORT_SYMBOL(__vfs_setxattr);
+
+/**
+ *  __vfs_setxattr_noperm - perform setxattr operation without performing
+ *  permission checks.
+ *
+ *  @idmap: idmap of the mount the inode was found from
+ *  @dentry: object to perform setxattr on
+ *  @name: xattr name to set
+ *  @value: value to set @name to
+ *  @size: size of @value
+ *  @flags: flags to pass into filesystem operations
+ *
+ *  returns the result of the internal setxattr or setsecurity operations.
+ *
+ *  This function requires the caller to lock the inode's i_mutex before it
+ *  is executed. It also assumes that the caller will make the appropriate
+ *  permission checks.
+ */
+int __vfs_setxattr_noperm(struct mnt_idmap *idmap,
+			  struct dentry *dentry, const char *name,
+			  const void *value, size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	int error = -EAGAIN;
+	int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
+				   XATTR_SECURITY_PREFIX_LEN);
+
+	if (issec)
+		inode->i_flags &= ~S_NOSEC;
+	if (inode->i_opflags & IOP_XATTR) {
+		error = __vfs_setxattr(idmap, dentry, inode, name, value,
+				       size, flags);
+		if (!error) {
+			fsnotify_xattr(dentry);
+			security_inode_post_setxattr(dentry, name, value,
+						     size, flags);
+		}
+	} else {
+		if (unlikely(is_bad_inode(inode)))
+			return -EIO;
+	}
+	if (error == -EAGAIN) {
+		error = -EOPNOTSUPP;
+
+		if (issec) {
+			const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+
+			error = security_inode_setsecurity(inode, suffix, value,
+							   size, flags);
+			if (!error)
+				fsnotify_xattr(dentry);
+		}
+	}
+
+	return error;
+}
+
+/**
+ * __vfs_setxattr_locked - set an extended attribute while holding the inode
+ * lock
+ *
+ *  @idmap: idmap of the mount of the target inode
+ *  @dentry: object to perform setxattr on
+ *  @name: xattr name to set
+ *  @value: value to set @name to
+ *  @size: size of @value
+ *  @flags: flags to pass into filesystem operations
+ *  @delegated_inode: on return, will contain an inode pointer that
+ *  a delegation was broken on, NULL if none.
+ */
+int
+__vfs_setxattr_locked(struct mnt_idmap *idmap, struct dentry *dentry,
+		      const char *name, const void *value, size_t size,
+		      int flags, struct inode **delegated_inode)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(idmap, inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	error = security_inode_setxattr(idmap, dentry, name, value, size,
+					flags);
+	if (error)
+		goto out;
+
+	error = try_break_deleg(inode, delegated_inode);
+	if (error)
+		goto out;
+
+	error = __vfs_setxattr_noperm(idmap, dentry, name, value,
+				      size, flags);
+
+out:
+	return error;
+}
+EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
+
+int
+vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
+	     const char *name, const void *value, size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+	const void  *orig_value = value;
+	int error;
+
+	if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
+		error = cap_convert_nscap(idmap, dentry, &value, size);
+		if (error < 0)
+			return error;
+		size = error;
+	}
+
+retry_deleg:
+	inode_lock(inode);
+	error = __vfs_setxattr_locked(idmap, dentry, name, value, size,
+				      flags, &delegated_inode);
+	inode_unlock(inode);
+
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
+	if (value != orig_value)
+		kfree(value);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_setxattr);
+
+static ssize_t
+xattr_getsecurity(struct mnt_idmap *idmap, struct inode *inode,
+		  const char *name, void *value, size_t size)
+{
+	void *buffer = NULL;
+	ssize_t len;
+
+	if (!value || !size) {
+		len = security_inode_getsecurity(idmap, inode, name,
+						 &buffer, false);
+		goto out_noalloc;
+	}
+
+	len = security_inode_getsecurity(idmap, inode, name, &buffer,
+					 true);
+	if (len < 0)
+		return len;
+	if (size < len) {
+		len = -ERANGE;
+		goto out;
+	}
+	memcpy(value, buffer, len);
+out:
+	kfree(buffer);
+out_noalloc:
+	return len;
+}
+
+/*
+ * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
+ *
+ * Allocate memory, if not already allocated, or re-allocate correct size,
+ * before retrieving the extended attribute.  The xattr value buffer should
+ * always be freed by the caller, even on error.
+ *
+ * Returns the result of alloc, if failed, or the getxattr operation.
+ */
+int
+vfs_getxattr_alloc(struct mnt_idmap *idmap, struct dentry *dentry,
+		   const char *name, char **xattr_value, size_t xattr_size,
+		   gfp_t flags)
+{
+	const struct xattr_handler *handler;
+	struct inode *inode = dentry->d_inode;
+	char *value = *xattr_value;
+	int error;
+
+	error = xattr_permission(idmap, inode, name, MAY_READ);
+	if (error)
+		return error;
+
+	handler = xattr_resolve_name(inode, &name);
+	if (IS_ERR(handler))
+		return PTR_ERR(handler);
+	if (!handler->get)
+		return -EOPNOTSUPP;
+	error = handler->get(handler, dentry, inode, name, NULL, 0);
+	if (error < 0)
+		return error;
+
+	if (!value || (error > xattr_size)) {
+		value = krealloc(*xattr_value, error + 1, flags);
+		if (!value)
+			return -ENOMEM;
+		memset(value, 0, error + 1);
+	}
+
+	error = handler->get(handler, dentry, inode, name, value, error);
+	*xattr_value = value;
+	return error;
+}
+
+ssize_t
+__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
+	       void *value, size_t size)
+{
+	const struct xattr_handler *handler;
+
+	if (is_posix_acl_xattr(name))
+		return -EOPNOTSUPP;
+
+	handler = xattr_resolve_name(inode, &name);
+	if (IS_ERR(handler))
+		return PTR_ERR(handler);
+	if (!handler->get)
+		return -EOPNOTSUPP;
+	return handler->get(handler, dentry, inode, name, value, size);
+}
+EXPORT_SYMBOL(__vfs_getxattr);
+
+ssize_t
+vfs_getxattr(struct mnt_idmap *idmap, struct dentry *dentry,
+	     const char *name, void *value, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(idmap, 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(idmap, inode, suffix, value,
+					    size);
+		/*
+		 * Only overwrite the return value if a security module
+		 * is actually active.
+		 */
+		if (ret == -EOPNOTSUPP)
+			goto nolsm;
+		return ret;
+	}
+nolsm:
+	return __vfs_getxattr(dentry, inode, name, value, size);
+}
+EXPORT_SYMBOL_GPL(vfs_getxattr);
+
+/**
+ * vfs_listxattr - retrieve \0 separated list of xattr names
+ * @dentry: the dentry from whose inode the xattr names are retrieved
+ * @list: buffer to store xattr names into
+ * @size: size of the buffer
+ *
+ * This function returns the names of all xattrs associated with the
+ * inode of @dentry.
+ *
+ * Note, for legacy reasons the vfs_listxattr() function lists POSIX
+ * ACLs as well. Since POSIX ACLs are decoupled from IOP_XATTR the
+ * vfs_listxattr() function doesn't check for this flag since a
+ * filesystem could implement POSIX ACLs without implementing any other
+ * xattrs.
+ *
+ * However, since all codepaths that remove IOP_XATTR also assign of
+ * inode operations that either don't implement or implement a stub
+ * ->listxattr() operation.
+ *
+ * Return: On success, the size of the buffer that was used. On error a
+ *         negative error code.
+ */
+ssize_t
+vfs_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+	struct inode *inode = d_inode(dentry);
+	ssize_t error;
+
+	error = security_inode_listxattr(dentry);
+	if (error)
+		return error;
+
+	if (inode->i_op->listxattr) {
+		error = inode->i_op->listxattr(dentry, list, size);
+	} else {
+		error = security_inode_listsecurity(inode, list, size);
+		if (size && error > size)
+			error = -ERANGE;
+	}
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_listxattr);
+
+int
+__vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
+		  const char *name)
+{
+	struct inode *inode = d_inode(dentry);
+	const struct xattr_handler *handler;
+
+	if (is_posix_acl_xattr(name))
+		return -EOPNOTSUPP;
+
+	handler = xattr_resolve_name(inode, &name);
+	if (IS_ERR(handler))
+		return PTR_ERR(handler);
+	if (!handler->set)
+		return -EOPNOTSUPP;
+	return handler->set(handler, idmap, dentry, inode, name, NULL, 0,
+			    XATTR_REPLACE);
+}
+EXPORT_SYMBOL(__vfs_removexattr);
+
+/**
+ * __vfs_removexattr_locked - set an extended attribute while holding the inode
+ * lock
+ *
+ *  @idmap: idmap of the mount of the target inode
+ *  @dentry: object to perform setxattr on
+ *  @name: name of xattr to remove
+ *  @delegated_inode: on return, will contain an inode pointer that
+ *  a delegation was broken on, NULL if none.
+ */
+int
+__vfs_removexattr_locked(struct mnt_idmap *idmap,
+			 struct dentry *dentry, const char *name,
+			 struct inode **delegated_inode)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(idmap, inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	error = security_inode_removexattr(idmap, dentry, name);
+	if (error)
+		goto out;
+
+	error = try_break_deleg(inode, delegated_inode);
+	if (error)
+		goto out;
+
+	error = __vfs_removexattr(idmap, dentry, name);
+
+	if (!error) {
+		fsnotify_xattr(dentry);
+		evm_inode_post_removexattr(dentry, name);
+	}
+
+out:
+	return error;
+}
+EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
+
+int
+vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
+		const char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	struct inode *delegated_inode = NULL;
+	int error;
+
+retry_deleg:
+	inode_lock(inode);
+	error = __vfs_removexattr_locked(idmap, dentry,
+					 name, &delegated_inode);
+	inode_unlock(inode);
+
+	if (delegated_inode) {
+		error = break_deleg_wait(&delegated_inode);
+		if (!error)
+			goto retry_deleg;
+	}
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_removexattr);
+
+/*
+ * Extended attribute SET operations
+ */
+
+int setxattr_copy(const char __user *name, struct xattr_ctx *ctx)
+{
+	int error;
+
+	if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
+		return -EINVAL;
+
+	error = strncpy_from_user(ctx->kname->name, name,
+				sizeof(ctx->kname->name));
+	if (error == 0 || error == sizeof(ctx->kname->name))
+		return  -ERANGE;
+	if (error < 0)
+		return error;
+
+	error = 0;
+	if (ctx->size) {
+		if (ctx->size > XATTR_SIZE_MAX)
+			return -E2BIG;
+
+		ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size);
+		if (IS_ERR(ctx->kvalue)) {
+			error = PTR_ERR(ctx->kvalue);
+			ctx->kvalue = NULL;
+		}
+	}
+
+	return error;
+}
+
+int do_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
+		struct xattr_ctx *ctx)
+{
+	if (is_posix_acl_xattr(ctx->kname->name))
+		return do_set_acl(idmap, dentry, ctx->kname->name,
+				  ctx->kvalue, ctx->size);
+
+	return vfs_setxattr(idmap, dentry, ctx->kname->name,
+			ctx->kvalue, ctx->size, ctx->flags);
+}
+
+static long
+setxattr(struct mnt_idmap *idmap, struct dentry *d,
+	const char __user *name, const void __user *value, size_t size,
+	int flags)
+{
+	struct xattr_name kname;
+	struct xattr_ctx ctx = {
+		.cvalue   = value,
+		.kvalue   = NULL,
+		.size     = size,
+		.kname    = &kname,
+		.flags    = flags,
+	};
+	int error;
+
+	error = setxattr_copy(name, &ctx);
+	if (error)
+		return error;
+
+	error = do_setxattr(idmap, d, &ctx);
+
+	kvfree(ctx.kvalue);
+	return error;
+}
+
+static int path_setxattr(const char __user *pathname,
+			 const char __user *name, const void __user *value,
+			 size_t size, int flags, unsigned int lookup_flags)
+{
+	struct path path;
+	int error;
+
+retry:
+	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+	if (error)
+		return error;
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = setxattr(mnt_idmap(path.mnt), path.dentry, name,
+				 value, size, flags);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+	return error;
+}
+
+SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
+		const char __user *, name, const void __user *, value,
+		size_t, size, int, flags)
+{
+	return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
+}
+
+SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
+		const char __user *, name, const void __user *, value,
+		size_t, size, int, flags)
+{
+	return path_setxattr(pathname, name, value, size, flags, 0);
+}
+
+SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
+		const void __user *,value, size_t, size, int, flags)
+{
+	struct fd f = fdget(fd);
+	int error = -EBADF;
+
+	if (!f.file)
+		return error;
+	audit_file(f.file);
+	error = mnt_want_write_file(f.file);
+	if (!error) {
+		error = setxattr(file_mnt_idmap(f.file),
+				 f.file->f_path.dentry, name,
+				 value, size, flags);
+		mnt_drop_write_file(f.file);
+	}
+	fdput(f);
+	return error;
+}
+
+/*
+ * Extended attribute GET operations
+ */
+ssize_t
+do_getxattr(struct mnt_idmap *idmap, struct dentry *d,
+	struct xattr_ctx *ctx)
+{
+	ssize_t error;
+	char *kname = ctx->kname->name;
+
+	if (ctx->size) {
+		if (ctx->size > XATTR_SIZE_MAX)
+			ctx->size = XATTR_SIZE_MAX;
+		ctx->kvalue = kvzalloc(ctx->size, GFP_KERNEL);
+		if (!ctx->kvalue)
+			return -ENOMEM;
+	}
+
+	if (is_posix_acl_xattr(ctx->kname->name))
+		error = do_get_acl(idmap, d, kname, ctx->kvalue, ctx->size);
+	else
+		error = vfs_getxattr(idmap, d, kname, ctx->kvalue, ctx->size);
+	if (error > 0) {
+		if (ctx->size && copy_to_user(ctx->value, ctx->kvalue, error))
+			error = -EFAULT;
+	} else if (error == -ERANGE && ctx->size >= XATTR_SIZE_MAX) {
+		/* The file system tried to returned a value bigger
+		   than XATTR_SIZE_MAX bytes. Not possible. */
+		error = -E2BIG;
+	}
+
+	return error;
+}
+
+static ssize_t
+getxattr(struct mnt_idmap *idmap, struct dentry *d,
+	 const char __user *name, void __user *value, size_t size)
+{
+	ssize_t error;
+	struct xattr_name kname;
+	struct xattr_ctx ctx = {
+		.value    = value,
+		.kvalue   = NULL,
+		.size     = size,
+		.kname    = &kname,
+		.flags    = 0,
+	};
+
+	error = strncpy_from_user(kname.name, name, sizeof(kname.name));
+	if (error == 0 || error == sizeof(kname.name))
+		error = -ERANGE;
+	if (error < 0)
+		return error;
+
+	error =  do_getxattr(idmap, d, &ctx);
+
+	kvfree(ctx.kvalue);
+	return error;
+}
+
+static ssize_t path_getxattr(const char __user *pathname,
+			     const char __user *name, void __user *value,
+			     size_t size, unsigned int lookup_flags)
+{
+	struct path path;
+	ssize_t error;
+retry:
+	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+	if (error)
+		return error;
+	error = getxattr(mnt_idmap(path.mnt), path.dentry, name, value, size);
+	path_put(&path);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+	return error;
+}
+
+SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
+		const char __user *, name, void __user *, value, size_t, size)
+{
+	return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
+}
+
+SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
+		const char __user *, name, void __user *, value, size_t, size)
+{
+	return path_getxattr(pathname, name, value, size, 0);
+}
+
+SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
+		void __user *, value, size_t, size)
+{
+	struct fd f = fdget(fd);
+	ssize_t error = -EBADF;
+
+	if (!f.file)
+		return error;
+	audit_file(f.file);
+	error = getxattr(file_mnt_idmap(f.file), f.file->f_path.dentry,
+			 name, value, size);
+	fdput(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 = kvmalloc(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;
+	}
+
+	kvfree(klist);
+
+	return error;
+}
+
+static ssize_t path_listxattr(const char __user *pathname, char __user *list,
+			      size_t size, unsigned int lookup_flags)
+{
+	struct path path;
+	ssize_t error;
+retry:
+	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+	if (error)
+		return error;
+	error = listxattr(path.dentry, list, size);
+	path_put(&path);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+	return error;
+}
+
+SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
+		size_t, size)
+{
+	return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
+}
+
+SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
+		size_t, size)
+{
+	return path_listxattr(pathname, list, size, 0);
+}
+
+SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
+{
+	struct fd f = fdget(fd);
+	ssize_t error = -EBADF;
+
+	if (!f.file)
+		return error;
+	audit_file(f.file);
+	error = listxattr(f.file->f_path.dentry, list, size);
+	fdput(f);
+	return error;
+}
+
+/*
+ * Extended attribute REMOVE operations
+ */
+static long
+removexattr(struct mnt_idmap *idmap, 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;
+
+	if (is_posix_acl_xattr(kname))
+		return vfs_remove_acl(idmap, d, kname);
+
+	return vfs_removexattr(idmap, d, kname);
+}
+
+static int path_removexattr(const char __user *pathname,
+			    const char __user *name, unsigned int lookup_flags)
+{
+	struct path path;
+	int error;
+retry:
+	error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
+	if (error)
+		return error;
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = removexattr(mnt_idmap(path.mnt), path.dentry, name);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+	return error;
+}
+
+SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
+		const char __user *, name)
+{
+	return path_removexattr(pathname, name, LOOKUP_FOLLOW);
+}
+
+SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
+		const char __user *, name)
+{
+	return path_removexattr(pathname, name, 0);
+}
+
+SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
+{
+	struct fd f = fdget(fd);
+	int error = -EBADF;
+
+	if (!f.file)
+		return error;
+	audit_file(f.file);
+	error = mnt_want_write_file(f.file);
+	if (!error) {
+		error = removexattr(file_mnt_idmap(f.file),
+				    f.file->f_path.dentry, name);
+		mnt_drop_write_file(f.file);
+	}
+	fdput(f);
+	return error;
+}
+
+int xattr_list_one(char **buffer, ssize_t *remaining_size, const char *name)
+{
+	size_t len;
+
+	len = strlen(name) + 1;
+	if (*buffer) {
+		if (*remaining_size < len)
+			return -ERANGE;
+		memcpy(*buffer, name, len);
+		*buffer += len;
+	}
+	*remaining_size -= len;
+	return 0;
+}
+
+/**
+ * generic_listxattr - run through a dentry's xattr list() operations
+ * @dentry: dentry to list the xattrs
+ * @buffer: result buffer
+ * @buffer_size: size of @buffer
+ *
+ * Combine the results of the list() operation from every xattr_handler in the
+ * xattr_handler stack.
+ *
+ * Note that this will not include the entries for POSIX ACLs.
+ */
+ssize_t
+generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
+{
+	const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
+	ssize_t remaining_size = buffer_size;
+	int err = 0;
+
+	for_each_xattr_handler(handlers, handler) {
+		if (!handler->name || (handler->list && !handler->list(dentry)))
+			continue;
+		err = xattr_list_one(&buffer, &remaining_size, handler->name);
+		if (err)
+			return err;
+	}
+
+	return err ? err : buffer_size - remaining_size;
+}
+EXPORT_SYMBOL(generic_listxattr);
+
+/**
+ * xattr_full_name  -  Compute full attribute name from suffix
+ *
+ * @handler:	handler of the xattr_handler operation
+ * @name:	name passed to the xattr_handler operation
+ *
+ * The get and set xattr handler operations are called with the remainder of
+ * the attribute name after skipping the handler's prefix: for example, "foo"
+ * is passed to the get operation of a handler with prefix "user." to get
+ * attribute "user.foo".  The full name is still "there" in the name though.
+ *
+ * Note: the list xattr handler operation when called from the vfs is passed a
+ * NULL name; some file systems use this operation internally, with varying
+ * semantics.
+ */
+const char *xattr_full_name(const struct xattr_handler *handler,
+			    const char *name)
+{
+	size_t prefix_len = strlen(xattr_prefix(handler));
+
+	return name - prefix_len;
+}
+EXPORT_SYMBOL(xattr_full_name);
+
+/**
+ * simple_xattr_space - estimate the memory used by a simple xattr
+ * @name: the full name of the xattr
+ * @size: the size of its value
+ *
+ * This takes no account of how much larger the two slab objects actually are:
+ * that would depend on the slab implementation, when what is required is a
+ * deterministic number, which grows with name length and size and quantity.
+ *
+ * Return: The approximate number of bytes of memory used by such an xattr.
+ */
+size_t simple_xattr_space(const char *name, size_t size)
+{
+	/*
+	 * Use "40" instead of sizeof(struct simple_xattr), to return the
+	 * same result on 32-bit and 64-bit, and even if simple_xattr grows.
+	 */
+	return 40 + size + strlen(name);
+}
+
+/**
+ * simple_xattr_free - free an xattr object
+ * @xattr: the xattr object
+ *
+ * Free the xattr object. Can handle @xattr being NULL.
+ */
+void simple_xattr_free(struct simple_xattr *xattr)
+{
+	if (xattr)
+		kfree(xattr->name);
+	kvfree(xattr);
+}
+
+/**
+ * simple_xattr_alloc - allocate new xattr object
+ * @value: value of the xattr object
+ * @size: size of @value
+ *
+ * Allocate a new xattr object and initialize respective members. The caller is
+ * responsible for handling the name of the xattr.
+ *
+ * Return: On success a new xattr object is returned. On failure NULL is
+ * returned.
+ */
+struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
+{
+	struct simple_xattr *new_xattr;
+	size_t len;
+
+	/* wrap around? */
+	len = sizeof(*new_xattr) + size;
+	if (len < sizeof(*new_xattr))
+		return NULL;
+
+	new_xattr = kvmalloc(len, GFP_KERNEL_ACCOUNT);
+	if (!new_xattr)
+		return NULL;
+
+	new_xattr->size = size;
+	memcpy(new_xattr->value, value, size);
+	return new_xattr;
+}
+
+/**
+ * rbtree_simple_xattr_cmp - compare xattr name with current rbtree xattr entry
+ * @key: xattr name
+ * @node: current node
+ *
+ * Compare the xattr name with the xattr name attached to @node in the rbtree.
+ *
+ * Return: Negative value if continuing left, positive if continuing right, 0
+ * if the xattr attached to @node matches @key.
+ */
+static int rbtree_simple_xattr_cmp(const void *key, const struct rb_node *node)
+{
+	const char *xattr_name = key;
+	const struct simple_xattr *xattr;
+
+	xattr = rb_entry(node, struct simple_xattr, rb_node);
+	return strcmp(xattr->name, xattr_name);
+}
+
+/**
+ * rbtree_simple_xattr_node_cmp - compare two xattr rbtree nodes
+ * @new_node: new node
+ * @node: current node
+ *
+ * Compare the xattr attached to @new_node with the xattr attached to @node.
+ *
+ * Return: Negative value if continuing left, positive if continuing right, 0
+ * if the xattr attached to @new_node matches the xattr attached to @node.
+ */
+static int rbtree_simple_xattr_node_cmp(struct rb_node *new_node,
+					const struct rb_node *node)
+{
+	struct simple_xattr *xattr;
+	xattr = rb_entry(new_node, struct simple_xattr, rb_node);
+	return rbtree_simple_xattr_cmp(xattr->name, node);
+}
+
+/**
+ * simple_xattr_get - get an xattr object
+ * @xattrs: the header of the xattr object
+ * @name: the name of the xattr to retrieve
+ * @buffer: the buffer to store the value into
+ * @size: the size of @buffer
+ *
+ * Try to find and retrieve the xattr object associated with @name.
+ * If @buffer is provided store the value of @xattr in @buffer
+ * otherwise just return the length. The size of @buffer is limited
+ * to XATTR_SIZE_MAX which currently is 65536.
+ *
+ * Return: On success the length of the xattr value is returned. On error a
+ * negative error code is returned.
+ */
+int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
+		     void *buffer, size_t size)
+{
+	struct simple_xattr *xattr = NULL;
+	struct rb_node *rbp;
+	int ret = -ENODATA;
+
+	read_lock(&xattrs->lock);
+	rbp = rb_find(name, &xattrs->rb_root, rbtree_simple_xattr_cmp);
+	if (rbp) {
+		xattr = rb_entry(rbp, struct simple_xattr, rb_node);
+		ret = xattr->size;
+		if (buffer) {
+			if (size < xattr->size)
+				ret = -ERANGE;
+			else
+				memcpy(buffer, xattr->value, xattr->size);
+		}
+	}
+	read_unlock(&xattrs->lock);
+	return ret;
+}
+
+/**
+ * simple_xattr_set - set an xattr object
+ * @xattrs: the header of the xattr object
+ * @name: the name of the xattr to retrieve
+ * @value: the value to store along the xattr
+ * @size: the size of @value
+ * @flags: the flags determining how to set the xattr
+ *
+ * Set a new xattr object.
+ * If @value is passed a new xattr object will be allocated. If XATTR_REPLACE
+ * is specified in @flags a matching xattr object for @name must already exist.
+ * If it does it will be replaced with the new xattr object. If it doesn't we
+ * fail. If XATTR_CREATE is specified and a matching xattr does already exist
+ * we fail. If it doesn't we create a new xattr. If @flags is zero we simply
+ * insert the new xattr replacing any existing one.
+ *
+ * If @value is empty and a matching xattr object is found we delete it if
+ * XATTR_REPLACE is specified in @flags or @flags is zero.
+ *
+ * If @value is empty and no matching xattr object for @name is found we do
+ * nothing if XATTR_CREATE is specified in @flags or @flags is zero. For
+ * XATTR_REPLACE we fail as mentioned above.
+ *
+ * Return: On success, the removed or replaced xattr is returned, to be freed
+ * by the caller; or NULL if none. On failure a negative error code is returned.
+ */
+struct simple_xattr *simple_xattr_set(struct simple_xattrs *xattrs,
+				      const char *name, const void *value,
+				      size_t size, int flags)
+{
+	struct simple_xattr *old_xattr = NULL, *new_xattr = NULL;
+	struct rb_node *parent = NULL, **rbp;
+	int err = 0, ret;
+
+	/* value == NULL means remove */
+	if (value) {
+		new_xattr = simple_xattr_alloc(value, size);
+		if (!new_xattr)
+			return ERR_PTR(-ENOMEM);
+
+		new_xattr->name = kstrdup(name, GFP_KERNEL_ACCOUNT);
+		if (!new_xattr->name) {
+			simple_xattr_free(new_xattr);
+			return ERR_PTR(-ENOMEM);
+		}
+	}
+
+	write_lock(&xattrs->lock);
+	rbp = &xattrs->rb_root.rb_node;
+	while (*rbp) {
+		parent = *rbp;
+		ret = rbtree_simple_xattr_cmp(name, *rbp);
+		if (ret < 0)
+			rbp = &(*rbp)->rb_left;
+		else if (ret > 0)
+			rbp = &(*rbp)->rb_right;
+		else
+			old_xattr = rb_entry(*rbp, struct simple_xattr, rb_node);
+		if (old_xattr)
+			break;
+	}
+
+	if (old_xattr) {
+		/* Fail if XATTR_CREATE is requested and the xattr exists. */
+		if (flags & XATTR_CREATE) {
+			err = -EEXIST;
+			goto out_unlock;
+		}
+
+		if (new_xattr)
+			rb_replace_node(&old_xattr->rb_node,
+					&new_xattr->rb_node, &xattrs->rb_root);
+		else
+			rb_erase(&old_xattr->rb_node, &xattrs->rb_root);
+	} else {
+		/* Fail if XATTR_REPLACE is requested but no xattr is found. */
+		if (flags & XATTR_REPLACE) {
+			err = -ENODATA;
+			goto out_unlock;
+		}
+
+		/*
+		 * If XATTR_CREATE or no flags are specified together with a
+		 * new value simply insert it.
+		 */
+		if (new_xattr) {
+			rb_link_node(&new_xattr->rb_node, parent, rbp);
+			rb_insert_color(&new_xattr->rb_node, &xattrs->rb_root);
+		}
+
+		/*
+		 * If XATTR_CREATE or no flags are specified and neither an
+		 * old or new xattr exist then we don't need to do anything.
+		 */
+	}
+
+out_unlock:
+	write_unlock(&xattrs->lock);
+	if (!err)
+		return old_xattr;
+	simple_xattr_free(new_xattr);
+	return ERR_PTR(err);
+}
+
+static bool xattr_is_trusted(const char *name)
+{
+	return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
+}
+
+/**
+ * simple_xattr_list - list all xattr objects
+ * @inode: inode from which to get the xattrs
+ * @xattrs: the header of the xattr object
+ * @buffer: the buffer to store all xattrs into
+ * @size: the size of @buffer
+ *
+ * List all xattrs associated with @inode. If @buffer is NULL we returned
+ * the required size of the buffer. If @buffer is provided we store the
+ * xattrs value into it provided it is big enough.
+ *
+ * Note, the number of xattr names that can be listed with listxattr(2) is
+ * limited to XATTR_LIST_MAX aka 65536 bytes. If a larger buffer is passed
+ * then vfs_listxattr() caps it to XATTR_LIST_MAX and if more xattr names
+ * are found it will return -E2BIG.
+ *
+ * Return: On success the required size or the size of the copied xattrs is
+ * returned. On error a negative error code is returned.
+ */
+ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
+			  char *buffer, size_t size)
+{
+	bool trusted = ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
+	struct simple_xattr *xattr;
+	struct rb_node *rbp;
+	ssize_t remaining_size = size;
+	int err = 0;
+
+	err = posix_acl_listxattr(inode, &buffer, &remaining_size);
+	if (err)
+		return err;
+
+	read_lock(&xattrs->lock);
+	for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
+		xattr = rb_entry(rbp, struct simple_xattr, rb_node);
+
+		/* skip "trusted." attributes for unprivileged callers */
+		if (!trusted && xattr_is_trusted(xattr->name))
+			continue;
+
+		err = xattr_list_one(&buffer, &remaining_size, xattr->name);
+		if (err)
+			break;
+	}
+	read_unlock(&xattrs->lock);
+
+	return err ? err : size - remaining_size;
+}
+
+/**
+ * rbtree_simple_xattr_less - compare two xattr rbtree nodes
+ * @new_node: new node
+ * @node: current node
+ *
+ * Compare the xattr attached to @new_node with the xattr attached to @node.
+ * Note that this function technically tolerates duplicate entries.
+ *
+ * Return: True if insertion point in the rbtree is found.
+ */
+static bool rbtree_simple_xattr_less(struct rb_node *new_node,
+				     const struct rb_node *node)
+{
+	return rbtree_simple_xattr_node_cmp(new_node, node) < 0;
+}
+
+/**
+ * simple_xattr_add - add xattr objects
+ * @xattrs: the header of the xattr object
+ * @new_xattr: the xattr object to add
+ *
+ * Add an xattr object to @xattrs. This assumes no replacement or removal
+ * of matching xattrs is wanted. Should only be called during inode
+ * initialization when a few distinct initial xattrs are supposed to be set.
+ */
+void simple_xattr_add(struct simple_xattrs *xattrs,
+		      struct simple_xattr *new_xattr)
+{
+	write_lock(&xattrs->lock);
+	rb_add(&new_xattr->rb_node, &xattrs->rb_root, rbtree_simple_xattr_less);
+	write_unlock(&xattrs->lock);
+}
+
+/**
+ * simple_xattrs_init - initialize new xattr header
+ * @xattrs: header to initialize
+ *
+ * Initialize relevant fields of a an xattr header.
+ */
+void simple_xattrs_init(struct simple_xattrs *xattrs)
+{
+	xattrs->rb_root = RB_ROOT;
+	rwlock_init(&xattrs->lock);
+}
+
+/**
+ * simple_xattrs_free - free xattrs
+ * @xattrs: xattr header whose xattrs to destroy
+ * @freed_space: approximate number of bytes of memory freed from @xattrs
+ *
+ * Destroy all xattrs in @xattr. When this is called no one can hold a
+ * reference to any of the xattrs anymore.
+ */
+void simple_xattrs_free(struct simple_xattrs *xattrs, size_t *freed_space)
+{
+	struct rb_node *rbp;
+
+	if (freed_space)
+		*freed_space = 0;
+	rbp = rb_first(&xattrs->rb_root);
+	while (rbp) {
+		struct simple_xattr *xattr;
+		struct rb_node *rbp_next;
+
+		rbp_next = rb_next(rbp);
+		xattr = rb_entry(rbp, struct simple_xattr, rb_node);
+		rb_erase(&xattr->rb_node, &xattrs->rb_root);
+		if (freed_space)
+			*freed_space += simple_xattr_space(xattr->name,
+							   xattr->size);
+		simple_xattr_free(xattr);
+		rbp = rbp_next;
+	}
+}