1 files changed, 255 insertions, 0 deletions
diff --git a/fs/ecryptfs/netlink.c b/fs/ecryptfs/netlink.c
new file mode 100644
index 0000000..aba061d
--- /dev/null
+++ b/fs/ecryptfs/netlink.c
@@ -0,0 +1,255 @@
+/**
+ * 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 = (struct nlmsghdr*)skb->data;
+	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)->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 = (struct nlmsghdr *)skb->data;
+	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;
+}