fs/ecryptfs/netlink.c

   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, u8 msg_type,
  48                           u16 msg_flags, struct pid *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, pid_nr(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, pid_nr(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 {
 100         struct nlmsghdr *nlh = nlmsg_hdr(skb);
 101         struct ecryptfs_message *msg = NLMSG_DATA(nlh);
 102         struct pid *pid;
 103         int rc;
 104
 105         if (skb->len - NLMSG_HDRLEN - sizeof(*msg) != msg->data_len) {
 106                 rc = -EINVAL;
 107                 ecryptfs_printk(KERN_ERR, "Received netlink message with "
 108                                 "incorrectly specified data length\n");
 109                 goto out;
 110         }
 111         pid = find_get_pid(NETLINK_CREDS(skb)->pid);
 112         rc = ecryptfs_process_response(msg, NETLINK_CREDS(skb)->uid, NULL,
 113                                        pid, nlh->nlmsg_seq);
 114         put_pid(pid);
 115         if (rc)
 116                 printk(KERN_ERR
 117                        "Error processing response message; rc = [%d]\n", rc);
 118 out:
 119         return rc;
 120 }
 121
 122 /**
 123  * ecryptfs_process_nl_helo
 124  * @skb: The socket buffer containing the nlmsghdr in HELO state
 125  *
 126  * Gets uid and pid of the skb and adds the values to the daemon id
 127  * hash. Returns zero after adding a new daemon id to the hash list;
 128  * non-zero otherwise.
 129  */
 130 static int ecryptfs_process_nl_helo(struct sk_buff *skb)
 131 {
 132         struct pid *pid;
 133         int rc;
 134
 135         pid = find_get_pid(NETLINK_CREDS(skb)->pid);
 136         rc = ecryptfs_process_helo(ECRYPTFS_TRANSPORT_NETLINK,
 137                                    NETLINK_CREDS(skb)->uid, NULL, pid);
 138         put_pid(pid);
 139         if (rc)
 140                 printk(KERN_WARNING "Error processing HELO; rc = [%d]\n", rc);
 141         return rc;
 142 }
 143
 144 /**
 145  * ecryptfs_process_nl_quit
 146  * @skb: The socket buffer containing the nlmsghdr in QUIT state
 147  *
 148  * Gets uid and pid of the skb and deletes the corresponding daemon
 149  * id, if it is the registered that is requesting the
 150  * deletion. Returns zero after deleting the desired daemon id;
 151  * non-zero otherwise.
 152  */
 153 static int ecryptfs_process_nl_quit(struct sk_buff *skb)
 154 {
 155         struct pid *pid;
 156         int rc;
 157
 158         pid = find_get_pid(NETLINK_CREDS(skb)->pid);
 159         rc = ecryptfs_process_quit(NETLINK_CREDS(skb)->uid, NULL, pid);
 160         put_pid(pid);
 161         if (rc)
 162                 printk(KERN_WARNING
 163                        "Error processing QUIT message; rc = [%d]\n", rc);
 164         return rc;
 165 }
 166
 167 /**
 168  * ecryptfs_receive_nl_message
 169  *
 170  * Callback function called by netlink system when a message arrives.
 171  * If the message looks to be valid, then an attempt is made to assign
 172  * it to its desired netlink context element and wake up the process
 173  * that is waiting for a response.
 174  */
 175 static void ecryptfs_receive_nl_message(struct sk_buff *skb)
 176 {
 177         struct nlmsghdr *nlh;
 178
 179         nlh = nlmsg_hdr(skb);
 180         if (!NLMSG_OK(nlh, skb->len)) {
 181                 ecryptfs_printk(KERN_ERR, "Received corrupt netlink "
 182                                 "message\n");
 183                 goto free;
 184         }
 185         switch (nlh->nlmsg_type) {
 186                 case ECRYPTFS_MSG_RESPONSE:
 187                         if (ecryptfs_process_nl_response(skb)) {
 188                                 ecryptfs_printk(KERN_WARNING, "Failed to "
 189                                                 "deliver netlink response to "
 190                                                 "requesting operation\n");
 191                         }
 192                         break;
 193                 case ECRYPTFS_MSG_HELO:
 194                         if (ecryptfs_process_nl_helo(skb)) {
 195                                 ecryptfs_printk(KERN_WARNING, "Failed to "
 196                                                 "fulfill HELO request\n");
 197                         }
 198                         break;
 199                 case ECRYPTFS_MSG_QUIT:
 200                         if (ecryptfs_process_nl_quit(skb)) {
 201                                 ecryptfs_printk(KERN_WARNING, "Failed to "
 202                                                 "fulfill QUIT request\n");
 203                         }
 204                         break;
 205                 default:
 206                         ecryptfs_printk(KERN_WARNING, "Dropping netlink "
 207                                         "message of unrecognized type [%d]\n",
 208                                         nlh->nlmsg_type);
 209                         break;
 210         }
 211 free:
 212         kfree_skb(skb);
 213 }
 214
 215 /**
 216  * ecryptfs_init_netlink
 217  *
 218  * Initializes the daemon id hash list, netlink context array, and
 219  * necessary locks.  Returns zero upon success; non-zero upon error.
 220  */
 221 int ecryptfs_init_netlink(void)
 222 {
 223         int rc;
 224
 225         ecryptfs_nl_sock = netlink_kernel_create(&init_net, NETLINK_ECRYPTFS, 0,
 226                                                  ecryptfs_receive_nl_message,
 227                                                  NULL, THIS_MODULE);
 228         if (!ecryptfs_nl_sock) {
 229                 rc = -EIO;
 230                 ecryptfs_printk(KERN_ERR, "Failed to create netlink socket\n");
 231                 goto out;
 232         }
 233         ecryptfs_nl_sock->sk_sndtimeo = ECRYPTFS_DEFAULT_SEND_TIMEOUT;
 234         rc = 0;
 235 out:
 236         return rc;
 237 }
 238
 239 /**
 240  * ecryptfs_release_netlink
 241  *
 242  * Frees all memory used by the netlink context array and releases the
 243  * netlink socket.
 244  */
 245 void ecryptfs_release_netlink(void)
 246 {
 247         netlink_kernel_release(ecryptfs_nl_sock);
 248         ecryptfs_nl_sock = NULL;
 249 }