[net-next-2.6.git] / fs / ecryptfs / netlink.c

/**
 * 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;
}
Commit	Line	Data
88b4a07e MH	1	/**
	2	* eCryptfs: Linux filesystem encryption layer
	3	*
	4	* Copyright (C) 2004-2006 International Business Machines Corp.
	5	* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
	6	* Tyler Hicks <tyhicks@ou.edu>
	7	*
	8	* This program is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU General Public License version
	10	* 2 as published by the Free Software Foundation.
	11	*
	12	* This program is distributed in the hope that it will be useful, but
	13	* WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	15	* General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	20	* 02111-1307, USA.
	21	*/
	22
	23	#include <net/sock.h>
	24	#include <linux/hash.h>
	25	#include <linux/random.h>
	26	#include "ecryptfs_kernel.h"
	27
	28	static struct sock *ecryptfs_nl_sock;
	29
	30	/**
	31	* ecryptfs_send_netlink
	32	* @data: The data to include as the payload
	33	* @data_len: The byte count of the data
	34	* @msg_ctx: The netlink context that will be used to handle the
	35	* response message
	36	* @msg_type: The type of netlink message to send
	37	* @msg_flags: The flags to include in the netlink header
	38	* @daemon_pid: The process id of the daemon to send the message to
	39	*
	40	* Sends the data to the specified daemon pid and uses the netlink
	41	* context element to store the data needed for validation upon
	42	* receiving the response. The data and the netlink context can be
	43	* null if just sending a netlink header is sufficient. Returns zero
	44	* upon sending the message; non-zero upon error.
	45	*/
	46	int ecryptfs_send_netlink(char *data, int data_len,
	47	struct ecryptfs_msg_ctx *msg_ctx, u16 msg_type,
	48	u16 msg_flags, pid_t daemon_pid)
	49	{
	50	struct sk_buff *skb;
	51	struct nlmsghdr *nlh;
	52	struct ecryptfs_message *msg;
	53	size_t payload_len;
	54	int rc;
	55
	56	payload_len = ((data && data_len) ? (sizeof(*msg) + data_len) : 0);
	57	skb = alloc_skb(NLMSG_SPACE(payload_len), GFP_KERNEL);
	58	if (!skb) {
	59	rc = -ENOMEM;
	60	ecryptfs_printk(KERN_ERR, "Failed to allocate socket buffer\n");
	61	goto out;
	62	}
	63	nlh = NLMSG_PUT(skb, daemon_pid, msg_ctx ? msg_ctx->counter : 0,
	64	msg_type, payload_len);
65	nlh->nlmsg_flags = msg_flags;
66	if (msg_ctx && payload_len) {
67	msg = (struct ecryptfs_message *)NLMSG_DATA(nlh);
68	msg->index = msg_ctx->index;
69	msg->data_len = data_len;
70	memcpy(msg->data, data, data_len);
71	}
72	rc = netlink_unicast(ecryptfs_nl_sock, skb, daemon_pid, 0);
73	if (rc < 0) {
74	ecryptfs_printk(KERN_ERR, "Failed to send eCryptfs netlink "
75	"message; rc = [%d]\n", rc);
76	goto out;
77	}
78	rc = 0;
79	goto out;
80	nlmsg_failure:
81	rc = -EMSGSIZE;
82	kfree_skb(skb);
83	out:
84	return rc;
85	}
86
87	/**
88	* ecryptfs_process_nl_reponse
89	* @skb: The socket buffer containing the netlink message of state
90	* RESPONSE
91	*
92	* Processes a response message after sending a operation request to
93	* userspace. Attempts to assign the msg to a netlink context element
94	* at the index specified in the msg. The sk_buff and nlmsghdr must
95	* be validated before this function. Returns zero upon delivery to
96	* desired context element; non-zero upon delivery failure or error.
97	*/
98	static int ecryptfs_process_nl_response(struct sk_buff *skb)
99	{
b529ccf2	100	struct nlmsghdr *nlh = nlmsg_hdr(skb);
88b4a07e MH	101	struct ecryptfs_message *msg = NLMSG_DATA(nlh);
	102	int rc;
	103
	104	if (skb->len - NLMSG_HDRLEN - sizeof(*msg) != msg->data_len) {
	105	rc = -EINVAL;
	106	ecryptfs_printk(KERN_ERR, "Received netlink message with "
	107	"incorrectly specified data length\n");
	108	goto out;
	109	}
dddfa461 MH	110	rc = ecryptfs_process_response(msg, NETLINK_CREDS(skb)->uid,
dddfa461 MH	111	NETLINK_CREDS(skb)->pid, nlh->nlmsg_seq);
88b4a07e MH	112	if (rc)
	113	printk(KERN_ERR
	114	"Error processing response message; rc = [%d]\n", rc);
	115	out:
	116	return rc;
	117	}
	118
	119	/**
	120	* ecryptfs_process_nl_helo
	121	* @skb: The socket buffer containing the nlmsghdr in HELO state
	122	*
	123	* Gets uid and pid of the skb and adds the values to the daemon id
	124	* hash. Returns zero after adding a new daemon id to the hash list;
	125	* non-zero otherwise.
	126	*/
	127	static int ecryptfs_process_nl_helo(struct sk_buff *skb)
	128	{
	129	int rc;
	130
	131	rc = ecryptfs_process_helo(ECRYPTFS_TRANSPORT_NETLINK,
	132	NETLINK_CREDS(skb)->uid,
	133	NETLINK_CREDS(skb)->pid);
	134	if (rc)
	135	printk(KERN_WARNING "Error processing HELO; rc = [%d]\n", rc);
	136	return rc;
	137	}
	138
	139	/**
	140	* ecryptfs_process_nl_quit
	141	* @skb: The socket buffer containing the nlmsghdr in QUIT state
	142	*
	143	* Gets uid and pid of the skb and deletes the corresponding daemon
	144	* id, if it is the registered that is requesting the
	145	* deletion. Returns zero after deleting the desired daemon id;
	146	* non-zero otherwise.
	147	*/
	148	static int ecryptfs_process_nl_quit(struct sk_buff *skb)
	149	{
	150	int rc;
	151
	152	rc = ecryptfs_process_quit(NETLINK_CREDS(skb)->uid,
	153	NETLINK_CREDS(skb)->pid);
	154	if (rc)
	155	printk(KERN_WARNING
	156	"Error processing QUIT message; rc = [%d]\n", rc);
	157	return rc;
	158	}
	159
	160	/**
	161	* ecryptfs_receive_nl_message
	162	*
	163	* Callback function called by netlink system when a message arrives.
	164	* If the message looks to be valid, then an attempt is made to assign
	165	* it to its desired netlink context element and wake up the process
	166	* that is waiting for a response.
	167	*/
	168	static void ecryptfs_receive_nl_message(struct sock *sk, int len)
	169	{
	170	struct sk_buff *skb;
	171	struct nlmsghdr *nlh;
	172	int rc = 0; /* skb_recv_datagram requires this */
	173
	174	receive:
	175	skb = skb_recv_datagram(sk, 0, 0, &rc);
176	if (rc == -EINTR)
177	goto receive;
178	else if (rc < 0) {
179	ecryptfs_printk(KERN_ERR, "Error occurred while "
180	"receiving eCryptfs netlink message; "
181	"rc = [%d]\n", rc);
182	return;
183	}
b529ccf2	184	nlh = nlmsg_hdr(skb);
88b4a07e MH	185	if (!NLMSG_OK(nlh, skb->len)) {
	186	ecryptfs_printk(KERN_ERR, "Received corrupt netlink "
	187	"message\n");
	188	goto free;
	189	}
	190	switch (nlh->nlmsg_type) {
	191	case ECRYPTFS_NLMSG_RESPONSE:
	192	if (ecryptfs_process_nl_response(skb)) {
	193	ecryptfs_printk(KERN_WARNING, "Failed to "
	194	"deliver netlink response to "
	195	"requesting operation\n");
	196	}
	197	break;
	198	case ECRYPTFS_NLMSG_HELO:
	199	if (ecryptfs_process_nl_helo(skb)) {
	200	ecryptfs_printk(KERN_WARNING, "Failed to "
	201	"fulfill HELO request\n");
	202	}
	203	break;
	204	case ECRYPTFS_NLMSG_QUIT:
	205	if (ecryptfs_process_nl_quit(skb)) {
	206	ecryptfs_printk(KERN_WARNING, "Failed to "
	207	"fulfill QUIT request\n");
	208	}
	209	break;
	210	default:
	211	ecryptfs_printk(KERN_WARNING, "Dropping netlink "
	212	"message of unrecognized type [%d]\n",
	213	nlh->nlmsg_type);
	214	break;
	215	}
	216	free:
	217	kfree_skb(skb);
	218	}
	219
	220	/**
	221	* ecryptfs_init_netlink
	222	*
	223	* Initializes the daemon id hash list, netlink context array, and
	224	* necessary locks. Returns zero upon success; non-zero upon error.
	225	*/
	226	int ecryptfs_init_netlink(void)
	227	{
	228	int rc;
	229
	230	ecryptfs_nl_sock = netlink_kernel_create(NETLINK_ECRYPTFS, 0,
	231	ecryptfs_receive_nl_message,
	232	THIS_MODULE);
	233	if (!ecryptfs_nl_sock) {
	234	rc = -EIO;
	235	ecryptfs_printk(KERN_ERR, "Failed to create netlink socket\n");
	236	goto out;
	237	}
	238	ecryptfs_nl_sock->sk_sndtimeo = ECRYPTFS_DEFAULT_SEND_TIMEOUT;
	239	rc = 0;
	240	out:
	241	return rc;
	242	}
	243
	244	/**
	245	* ecryptfs_release_netlink
	246	*
	247	* Frees all memory used by the netlink context array and releases the
	248	* netlink socket.
249	*/
250	void ecryptfs_release_netlink(void)
251	{
252	if (ecryptfs_nl_sock && ecryptfs_nl_sock->sk_socket)
253	sock_release(ecryptfs_nl_sock->sk_socket);
254	ecryptfs_nl_sock = NULL;
255	}