text: // SPDX-License-Identifier: LGPL-2.1
  /*
   * Copyright IBM Corporation, 2010
   * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   */
  
  #include <linux/module.h>
  #include <linux/fs.h>
  #include <linux/sched.h>
  #include <linux/uio.h>
  #include <net/9p/9p.h>
  #include <net/9p/client.h>
  
  #include "fid.h"
  #include "xattr.h"
  
  ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
  			   void *buffer, size_t buffer_size)
  {
  	ssize_t retval;
  	u64 attr_size;
  	struct p9_fid *attr_fid;
  	struct kvec kvec = {.iov_base = buffer, .iov_len = buffer_size};
  	struct iov_iter to;
  	int err;
  
  	iov_iter_kvec(&to, READ, &kvec, 1, buffer_size);
  
  	attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
  	if (IS_ERR(attr_fid)) {
  		retval = PTR_ERR(attr_fid);
  		p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
  			 retval);
  		return retval;
  	}
  	if (attr_size > buffer_size) {
  		if (!buffer_size) /* request to get the attr_size */
  			retval = attr_size;
  		else
  			retval = -ERANGE;
  	} else {
  		iov_iter_truncate(&to, attr_size);
  		retval = p9_client_read(attr_fid, 0, &to, &err);
  		if (err)
  			retval = err;
  	}
  	p9_client_clunk(attr_fid);
  	return retval;
  }
  
  
  /*
   * v9fs_xattr_get()
   *
   * Copy an extended attribute into the buffer
   * provided, or compute the buffer size required.
   * Buffer is NULL to compute the size of the buffer required.
   *
   * Returns a negative error number on failure, or the number of bytes
   * used / required on success.
   */
  ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
  		       void *buffer, size_t buffer_size)
  {
  	struct p9_fid *fid;
  	int ret;
  
  	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
  		 name, buffer_size);
  	fid = v9fs_fid_lookup(dentry);
  	if (IS_ERR(fid))
  		return PTR_ERR(fid);
  	ret = v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
  	p9_client_clunk(fid);
  
  	return ret;
  }
  
  /*
   * v9fs_xattr_set()
   *
   * Create, replace or remove an extended attribute for this inode. Buffer
   * is NULL to remove an existing extended attribute, and non-NULL to
   * either replace an existing extended attribute, or create a new extended
   * attribute. The flags XATTR_REPLACE and XATTR_CREATE
   * specify that an extended attribute must exist and must not exist
   * previous to the call, respectively.
   *
   * Returns 0, or a negative error number on failure.
   */
  int v9fs_xattr_set(struct dentry *dentry, const char *name,
  		   const void *value, size_t value_len, int flags)
  {
  	int ret;
  	struct p9_fid *fid;
  
  	fid  = v9fs_fid_lookup(dentry);
  	if (IS_ERR(fid))
  		return PTR_ERR(fid);
  	ret = v9fs_fid_xattr_set(fid, name, value, value_len, flags);
  	p9_client_clunk(fid);
  	return ret;
  }
  
  int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
  		   const void *value, size_t value_len, int flags)
  {
  	struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
  	struct iov_iter from;
  	int retval, err;
  
  	iov_iter_kvec(&from, WRITE, &kvec, 1, value_len);
  
  	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
  		 name, value_len, flags);
  
  	/* Clone it */
  	fid = clone_fid(fid);
  	if (IS_ERR(fid))
  		return PTR_ERR(fid);
  
  	/*
  	 * On success fid points to xattr
  	 */
  	retval = p9_client_xattrcreate(fid, name, value_len, flags);
  	if (retval < 0)
  		p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
  			 retval);
  	else
  		p9_client_write(fid, 0, &from, &retval);
  	err = p9_client_clunk(fid);
  	if (!retval && err)
  		retval = err;
  	return retval;
  }
  
  ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
  {
  	return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
  }
  
  static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
  				  struct dentry *dentry, struct inode *inode,
  				  const char *name, void *buffer, size_t size)
  {
  	const char *full_name = xattr_full_name(handler, name);
  
  	return v9fs_xattr_get(dentry, full_name, buffer, size);
  }
  
  static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
  				  struct user_namespace *mnt_userns,
  				  struct dentry *dentry, struct inode *inode,
  				  const char *name, const void *value,
  				  size_t size, int flags)
  {
  	const char *full_name = xattr_full_name(handler, name);
  
  	return v9fs_xattr_set(dentry, full_name, value, size, flags);
  }
  
  static struct xattr_handler v9fs_xattr_user_handler = {
  	.prefix	= XATTR_USER_PREFIX,
  	.get	= v9fs_xattr_handler_get,
  	.set	= v9fs_xattr_handler_set,
  };
  
  static struct xattr_handler v9fs_xattr_trusted_handler = {
  	.prefix	= XATTR_TRUSTED_PREFIX,
  	.get	= v9fs_xattr_handler_get,
  	.set	= v9fs_xattr_handler_set,
  };
  
  #ifdef CONFIG_9P_FS_SECURITY
  static struct xattr_handler v9fs_xattr_security_handler = {
  	.prefix	= XATTR_SECURITY_PREFIX,
  	.get	= v9fs_xattr_handler_get,
  	.set	= v9fs_xattr_handler_set,
  };
  #endif
  
  const struct xattr_handler *v9fs_xattr_handlers[] = {
  	&v9fs_xattr_user_handler,
  	&v9fs_xattr_trusted_handler,
  #ifdef CONFIG_9P_FS_POSIX_ACL
  	&v9fs_xattr_acl_access_handler,
  	&v9fs_xattr_acl_default_handler,
  #endif
  #ifdef CONFIG_9P_FS_SECURITY
  	&v9fs_xattr_security_handler,
  #endif
  	NULL
  };
  