fs/ecryptfs/netlink.c - maze/linux - Git at Google

 /**
  * eCryptfs: Linux filesystem encryption layer
  *
  * Copyright (C) 2004-2006 International Business Machines Corp.
  *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
  *		Tyler Hicks <tyhicks@ou.edu>
  *
  * 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.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  * 02111-1307, USA.
  */

 #include <net/sock.h>
 #include <linux/hash.h>
 #include <linux/random.h>
 #include "ecryptfs_kernel.h"

 static struct sock *ecryptfs_nl_sock;

 /**
  * ecryptfs_send_netlink
  * @data: The data to include as the payload
  * @data_len: The byte count of the data
  * @msg_ctx: The netlink context that will be used to handle the
  *          response message
  * @msg_type: The type of netlink message to send
  * @msg_flags: The flags to include in the netlink header
  * @daemon_pid: The process id of the daemon to send the message to
  *
  * Sends the data to the specified daemon pid and uses the netlink
  * context element to store the data needed for validation upon
  * receiving the response.  The data and the netlink context can be
  * null if just sending a netlink header is sufficient.  Returns zero
  * upon sending the message; non-zero upon error.
  */
 int ecryptfs_send_netlink(char *data, int data_len,
 			  struct ecryptfs_msg_ctx *msg_ctx, u16 msg_type,
 			  u16 msg_flags, pid_t daemon_pid)
 {
 	struct sk_buff *skb;
 	struct nlmsghdr *nlh;
 	struct ecryptfs_message *msg;
 	size_t payload_len;
 	int rc;

 	payload_len = ((data && data_len) ? (sizeof(*msg) + data_len) : 0);
 	skb = alloc_skb(NLMSG_SPACE(payload_len), GFP_KERNEL);
 	if (!skb) {
 		rc = -ENOMEM;
 		ecryptfs_printk(KERN_ERR, "Failed to allocate socket buffer\n");
 		goto out;
 	}
 	nlh = NLMSG_PUT(skb, daemon_pid, msg_ctx ? msg_ctx->counter : 0,
 			msg_type, payload_len);
 	nlh->nlmsg_flags = msg_flags;
 	if (msg_ctx && payload_len) {
 		msg = (struct ecryptfs_message *)NLMSG_DATA(nlh);
 		msg->index = msg_ctx->index;
 		msg->data_len = data_len;
 		memcpy(msg->data, data, data_len);
 	}
 	rc = netlink_unicast(ecryptfs_nl_sock, skb, daemon_pid, 0);
 	if (rc < 0) {
 		ecryptfs_printk(KERN_ERR, "Failed to send eCryptfs netlink "
 				"message; rc = [%d]\n", rc);
 		goto out;
 	}
 	rc = 0;
 	goto out;
 nlmsg_failure:
 	rc = -EMSGSIZE;
 	kfree_skb(skb);
 out:
 	return rc;
 }

 /**
  * ecryptfs_process_nl_reponse
  * @skb: The socket buffer containing the netlink message of state
  *       RESPONSE
  *
  * Processes a response message after sending a operation request to
  * userspace.  Attempts to assign the msg to a netlink context element
  * at the index specified in the msg.  The sk_buff and nlmsghdr must
  * be validated before this function. Returns zero upon delivery to
  * desired context element; non-zero upon delivery failure or error.
  */
 static int ecryptfs_process_nl_response(struct sk_buff *skb)
 {
 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
 	struct ecryptfs_message *msg = NLMSG_DATA(nlh);
 	int rc;

 	if (skb->len - NLMSG_HDRLEN - sizeof(*msg) != msg->data_len) {
 		rc = -EINVAL;
 		ecryptfs_printk(KERN_ERR, "Received netlink message with "
 				"incorrectly specified data length\n");
 		goto out;
 	}
 	rc = ecryptfs_process_response(msg, NETLINK_CREDS(skb)->uid,
 				       NETLINK_CREDS(skb)->pid, nlh->nlmsg_seq);
 	if (rc)
 		printk(KERN_ERR
 		       "Error processing response message; rc = [%d]\n", rc);
 out:
 	return rc;
 }

 /**
  * ecryptfs_process_nl_helo
  * @skb: The socket buffer containing the nlmsghdr in HELO state
  *
  * Gets uid and pid of the skb and adds the values to the daemon id
  * hash. Returns zero after adding a new daemon id to the hash list;
  * non-zero otherwise.
  */
 static int ecryptfs_process_nl_helo(struct sk_buff *skb)
 {
 	int rc;

 	rc = ecryptfs_process_helo(ECRYPTFS_TRANSPORT_NETLINK,
 				   NETLINK_CREDS(skb)->uid,
 				   NETLINK_CREDS(skb)->pid);
 	if (rc)
 		printk(KERN_WARNING "Error processing HELO; rc = [%d]\n", rc);
 	return rc;
 }

 /**
  * ecryptfs_process_nl_quit
  * @skb: The socket buffer containing the nlmsghdr in QUIT state
  *
  * Gets uid and pid of the skb and deletes the corresponding daemon
  * id, if it is the registered that is requesting the
  * deletion. Returns zero after deleting the desired daemon id;
  * non-zero otherwise.
  */
 static int ecryptfs_process_nl_quit(struct sk_buff *skb)
 {
 	int rc;

 	rc = ecryptfs_process_quit(NETLINK_CREDS(skb)->uid,
 				   NETLINK_CREDS(skb)->pid);
 	if (rc)
 		printk(KERN_WARNING
 		       "Error processing QUIT message; rc = [%d]\n", rc);
 	return rc;
 }

 /**
  * ecryptfs_receive_nl_message
  *
  * Callback function called by netlink system when a message arrives.
  * If the message looks to be valid, then an attempt is made to assign
  * it to its desired netlink context element and wake up the process
  * that is waiting for a response.
  */
 static void ecryptfs_receive_nl_message(struct sock *sk, int len)
 {
 	struct sk_buff *skb;
 	struct nlmsghdr *nlh;
 	int rc = 0;	/* skb_recv_datagram requires this */

 receive:
 	skb = skb_recv_datagram(sk, 0, 0, &rc);
 	if (rc == -EINTR)
 		goto receive;
 	else if (rc < 0) {
 		ecryptfs_printk(KERN_ERR, "Error occurred while "
 				"receiving eCryptfs netlink message; "
 				"rc = [%d]\n", rc);
 		return;
 	}
 	nlh = nlmsg_hdr(skb);
 	if (!NLMSG_OK(nlh, skb->len)) {
 		ecryptfs_printk(KERN_ERR, "Received corrupt netlink "
 				"message\n");
 		goto free;
 	}
 	switch (nlh->nlmsg_type) {
 		case ECRYPTFS_NLMSG_RESPONSE:
 			if (ecryptfs_process_nl_response(skb)) {
 				ecryptfs_printk(KERN_WARNING, "Failed to "
 						"deliver netlink response to "
 						"requesting operation\n");
 			}
 			break;
 		case ECRYPTFS_NLMSG_HELO:
 			if (ecryptfs_process_nl_helo(skb)) {
 				ecryptfs_printk(KERN_WARNING, "Failed to "
 						"fulfill HELO request\n");
 			}
 			break;
 		case ECRYPTFS_NLMSG_QUIT:
 			if (ecryptfs_process_nl_quit(skb)) {
 				ecryptfs_printk(KERN_WARNING, "Failed to "
 						"fulfill QUIT request\n");
 			}
 			break;
 		default:
 			ecryptfs_printk(KERN_WARNING, "Dropping netlink "
 					"message of unrecognized type [%d]\n",
 					nlh->nlmsg_type);
 			break;
 	}
 free:
 	kfree_skb(skb);
 }

 /**
  * ecryptfs_init_netlink
  *
  * Initializes the daemon id hash list, netlink context array, and
  * necessary locks.  Returns zero upon success; non-zero upon error.
  */
 int ecryptfs_init_netlink(void)
 {
 	int rc;

 	ecryptfs_nl_sock = netlink_kernel_create(NETLINK_ECRYPTFS, 0,
 						 ecryptfs_receive_nl_message,
 						 THIS_MODULE);
 	if (!ecryptfs_nl_sock) {
 		rc = -EIO;
 		ecryptfs_printk(KERN_ERR, "Failed to create netlink socket\n");
 		goto out;
 	}
 	ecryptfs_nl_sock->sk_sndtimeo = ECRYPTFS_DEFAULT_SEND_TIMEOUT;
 	rc = 0;
 out:
 	return rc;
 }

 /**
  * ecryptfs_release_netlink
  *
  * Frees all memory used by the netlink context array and releases the
  * netlink socket.
  */
 void ecryptfs_release_netlink(void)
 {
 	if (ecryptfs_nl_sock && ecryptfs_nl_sock->sk_socket)
 		sock_release(ecryptfs_nl_sock->sk_socket);
 	ecryptfs_nl_sock = NULL;
 }
	/**
	* eCryptfs: Linux filesystem encryption layer
	*
	* Copyright (C) 2004-2006 International Business Machines Corp.
	* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
	* Tyler Hicks <tyhicks@ou.edu>
	*
	* 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.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	* 02111-1307, USA.
	*/

	#include <net/sock.h>
	#include <linux/hash.h>
	#include <linux/random.h>
	#include "ecryptfs_kernel.h"

	static struct sock *ecryptfs_nl_sock;

	/**
	* ecryptfs_send_netlink
	* @data: The data to include as the payload
	* @data_len: The byte count of the data
	* @msg_ctx: The netlink context that will be used to handle the
	* response message
	* @msg_type: The type of netlink message to send
	* @msg_flags: The flags to include in the netlink header
	* @daemon_pid: The process id of the daemon to send the message to
	*
	* Sends the data to the specified daemon pid and uses the netlink
	* context element to store the data needed for validation upon
	* receiving the response. The data and the netlink context can be
	* null if just sending a netlink header is sufficient. Returns zero
	* upon sending the message; non-zero upon error.
	*/
	int ecryptfs_send_netlink(char *data, int data_len,
	struct ecryptfs_msg_ctx *msg_ctx, u16 msg_type,
	u16 msg_flags, pid_t daemon_pid)
	{
	struct sk_buff *skb;
	struct nlmsghdr *nlh;
	struct ecryptfs_message *msg;
	size_t payload_len;
	int rc;

	payload_len = ((data && data_len) ? (sizeof(*msg) + data_len) : 0);
	skb = alloc_skb(NLMSG_SPACE(payload_len), GFP_KERNEL);
	if (!skb) {
	rc = -ENOMEM;
	ecryptfs_printk(KERN_ERR, "Failed to allocate socket buffer\n");
	goto out;
	}
	nlh = NLMSG_PUT(skb, daemon_pid, msg_ctx ? msg_ctx->counter : 0,
	msg_type, payload_len);
	nlh->nlmsg_flags = msg_flags;
	if (msg_ctx && payload_len) {
	msg = (struct ecryptfs_message *)NLMSG_DATA(nlh);
	msg->index = msg_ctx->index;
	msg->data_len = data_len;
	memcpy(msg->data, data, data_len);
	}
	rc = netlink_unicast(ecryptfs_nl_sock, skb, daemon_pid, 0);
	if (rc < 0) {
	ecryptfs_printk(KERN_ERR, "Failed to send eCryptfs netlink "
	"message; rc = [%d]\n", rc);
	goto out;
	}
	rc = 0;
	goto out;
	nlmsg_failure:
	rc = -EMSGSIZE;
	kfree_skb(skb);
	out:
	return rc;
	}

	/**
	* ecryptfs_process_nl_reponse
	* @skb: The socket buffer containing the netlink message of state
	* RESPONSE
	*
	* Processes a response message after sending a operation request to
	* userspace. Attempts to assign the msg to a netlink context element
	* at the index specified in the msg. The sk_buff and nlmsghdr must
	* be validated before this function. Returns zero upon delivery to
	* desired context element; non-zero upon delivery failure or error.
	*/
	static int ecryptfs_process_nl_response(struct sk_buff *skb)
	{
	struct nlmsghdr *nlh = nlmsg_hdr(skb);
	struct ecryptfs_message *msg = NLMSG_DATA(nlh);
	int rc;

	if (skb->len - NLMSG_HDRLEN - sizeof(*msg) != msg->data_len) {
	rc = -EINVAL;
	ecryptfs_printk(KERN_ERR, "Received netlink message with "
	"incorrectly specified data length\n");
	goto out;
	}
	rc = ecryptfs_process_response(msg, NETLINK_CREDS(skb)->uid,
	NETLINK_CREDS(skb)->pid, nlh->nlmsg_seq);
	if (rc)
	printk(KERN_ERR
	"Error processing response message; rc = [%d]\n", rc);
	out:
	return rc;
	}

	/**
	* ecryptfs_process_nl_helo
	* @skb: The socket buffer containing the nlmsghdr in HELO state
	*
	* Gets uid and pid of the skb and adds the values to the daemon id
	* hash. Returns zero after adding a new daemon id to the hash list;
	* non-zero otherwise.
	*/
	static int ecryptfs_process_nl_helo(struct sk_buff *skb)
	{
	int rc;

	rc = ecryptfs_process_helo(ECRYPTFS_TRANSPORT_NETLINK,
	NETLINK_CREDS(skb)->uid,
	NETLINK_CREDS(skb)->pid);
	if (rc)
	printk(KERN_WARNING "Error processing HELO; rc = [%d]\n", rc);
	return rc;
	}

	/**
	* ecryptfs_process_nl_quit
	* @skb: The socket buffer containing the nlmsghdr in QUIT state
	*
	* Gets uid and pid of the skb and deletes the corresponding daemon
	* id, if it is the registered that is requesting the
	* deletion. Returns zero after deleting the desired daemon id;
	* non-zero otherwise.
	*/
	static int ecryptfs_process_nl_quit(struct sk_buff *skb)
	{
	int rc;

	rc = ecryptfs_process_quit(NETLINK_CREDS(skb)->uid,
	NETLINK_CREDS(skb)->pid);
	if (rc)
	printk(KERN_WARNING
	"Error processing QUIT message; rc = [%d]\n", rc);
	return rc;
	}

	/**
	* ecryptfs_receive_nl_message
	*
	* Callback function called by netlink system when a message arrives.
	* If the message looks to be valid, then an attempt is made to assign
	* it to its desired netlink context element and wake up the process
	* that is waiting for a response.
	*/
	static void ecryptfs_receive_nl_message(struct sock *sk, int len)
	{
	struct sk_buff *skb;
	struct nlmsghdr *nlh;
	int rc = 0; /* skb_recv_datagram requires this */

	receive:
	skb = skb_recv_datagram(sk, 0, 0, &rc);
	if (rc == -EINTR)
	goto receive;
	else if (rc < 0) {
	ecryptfs_printk(KERN_ERR, "Error occurred while "
	"receiving eCryptfs netlink message; "
	"rc = [%d]\n", rc);
	return;
	}
	nlh = nlmsg_hdr(skb);
	if (!NLMSG_OK(nlh, skb->len)) {
	ecryptfs_printk(KERN_ERR, "Received corrupt netlink "
	"message\n");
	goto free;
	}
	switch (nlh->nlmsg_type) {
	case ECRYPTFS_NLMSG_RESPONSE:
	if (ecryptfs_process_nl_response(skb)) {
	ecryptfs_printk(KERN_WARNING, "Failed to "
	"deliver netlink response to "
	"requesting operation\n");
	}
	break;
	case ECRYPTFS_NLMSG_HELO:
	if (ecryptfs_process_nl_helo(skb)) {
	ecryptfs_printk(KERN_WARNING, "Failed to "
	"fulfill HELO request\n");
	}
	break;
	case ECRYPTFS_NLMSG_QUIT:
	if (ecryptfs_process_nl_quit(skb)) {
	ecryptfs_printk(KERN_WARNING, "Failed to "
	"fulfill QUIT request\n");
	}
	break;
	default:
	ecryptfs_printk(KERN_WARNING, "Dropping netlink "
	"message of unrecognized type [%d]\n",
	nlh->nlmsg_type);
	break;
	}
	free:
	kfree_skb(skb);
	}

	/**
	* ecryptfs_init_netlink
	*
	* Initializes the daemon id hash list, netlink context array, and
	* necessary locks. Returns zero upon success; non-zero upon error.
	*/
	int ecryptfs_init_netlink(void)
	{
	int rc;

	ecryptfs_nl_sock = netlink_kernel_create(NETLINK_ECRYPTFS, 0,
	ecryptfs_receive_nl_message,
	THIS_MODULE);
	if (!ecryptfs_nl_sock) {
	rc = -EIO;
	ecryptfs_printk(KERN_ERR, "Failed to create netlink socket\n");
	goto out;
	}
	ecryptfs_nl_sock->sk_sndtimeo = ECRYPTFS_DEFAULT_SEND_TIMEOUT;
	rc = 0;
	out:
	return rc;
	}

	/**
	* ecryptfs_release_netlink
	*
	* Frees all memory used by the netlink context array and releases the
	* netlink socket.
	*/
	void ecryptfs_release_netlink(void)
	{
	if (ecryptfs_nl_sock && ecryptfs_nl_sock->sk_socket)
	sock_release(ecryptfs_nl_sock->sk_socket);
	ecryptfs_nl_sock = NULL;
	}