1 files changed, 515 insertions, 0 deletions

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
new file mode 100644
index 000000000000..47d7e7b611f7
--- /dev/null
+++ b/fs/ecryptfs/messaging.c
@@ -0,0 +1,515 @@
+/**
+ * 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 "ecryptfs_kernel.h"
+
+static LIST_HEAD(ecryptfs_msg_ctx_free_list);
+static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
+static struct mutex ecryptfs_msg_ctx_lists_mux;
+
+static struct hlist_head *ecryptfs_daemon_id_hash;
+static struct mutex ecryptfs_daemon_id_hash_mux;
+static int ecryptfs_hash_buckets;
+#define ecryptfs_uid_hash(uid) \
+        hash_long((unsigned long)uid, ecryptfs_hash_buckets)
+
+static unsigned int ecryptfs_msg_counter;
+static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
+
+/**
+ * ecryptfs_acquire_free_msg_ctx
+ * @msg_ctx: The context that was acquired from the free list
+ *
+ * Acquires a context element from the free list and locks the mutex
+ * on the context.  Returns zero on success; non-zero on error or upon
+ * failure to acquire a free context element.  Be sure to lock the
+ * list mutex before calling.
+ */
+static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
+{
+        struct list_head *p;
+        int rc;
+
+        if (list_empty(&ecryptfs_msg_ctx_free_list)) {
+                ecryptfs_printk(KERN_WARNING, "The eCryptfs free "
+                                "context list is empty.  It may be helpful to "
+                                "specify the ecryptfs_message_buf_len "
+                                "parameter to be greater than the current "
+                                "value of [%d]\n", ecryptfs_message_buf_len);
+                rc = -ENOMEM;
+                goto out;
+        }
+        list_for_each(p, &ecryptfs_msg_ctx_free_list) {
+                *msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
+                if (mutex_trylock(&(*msg_ctx)->mux)) {
+                        (*msg_ctx)->task = current;
+                        rc = 0;
+                        goto out;
+                }
+        }
+        rc = -ENOMEM;
+out:
+        return rc;
+}
+
+/**
+ * ecryptfs_msg_ctx_free_to_alloc
+ * @msg_ctx: The context to move from the free list to the alloc list
+ *
+ * Be sure to lock the list mutex and the context mutex before
+ * calling.
+ */
+static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
+{
+        list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
+        msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
+        msg_ctx->counter = ++ecryptfs_msg_counter;
+}
+
+/**
+ * ecryptfs_msg_ctx_alloc_to_free
+ * @msg_ctx: The context to move from the alloc list to the free list
+ *
+ * Be sure to lock the list mutex and the context mutex before
+ * calling.
+ */
+static void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
+{
+        list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
+        if (msg_ctx->msg)
+                kfree(msg_ctx->msg);
+        msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
+}
+
+/**
+ * ecryptfs_find_daemon_id
+ * @uid: The user id which maps to the desired daemon id
+ * @id: If return value is zero, points to the desired daemon id
+ *      pointer
+ *
+ * Search the hash list for the given user id.  Returns zero if the
+ * user id exists in the list; non-zero otherwise.  The daemon id hash
+ * mutex should be held before calling this function.
+ */
+static int ecryptfs_find_daemon_id(uid_t uid, struct ecryptfs_daemon_id **id)
+{
+        struct hlist_node *elem;
+        int rc;
+
+        hlist_for_each_entry(*id, elem,
+                             &ecryptfs_daemon_id_hash[ecryptfs_uid_hash(uid)],
+                             id_chain) {
+                if ((*id)->uid == uid) {
+                        rc = 0;
+                        goto out;
+                }
+        }
+        rc = -EINVAL;
+out:
+        return rc;
+}
+
+static int ecryptfs_send_raw_message(unsigned int transport, u16 msg_type,
+                                     pid_t pid)
+{
+        int rc;
+
+        switch(transport) {
+        case ECRYPTFS_TRANSPORT_NETLINK:
+                rc = ecryptfs_send_netlink(NULL, 0, NULL, msg_type, 0, pid);
+                break;
+        case ECRYPTFS_TRANSPORT_CONNECTOR:
+        case ECRYPTFS_TRANSPORT_RELAYFS:
+        default:
+                rc = -ENOSYS;
+        }
+        return rc;
+}
+
+/**
+ * ecryptfs_process_helo
+ * @transport: The underlying transport (netlink, etc.)
+ * @uid: The user ID owner of the message
+ * @pid: The process ID for the userspace program that sent the
+ *       message
+ *
+ * Adds the uid and pid values to the daemon id hash.  If a uid
+ * already has a daemon pid registered, the daemon will be
+ * unregistered before the new daemon id is put into the hash list.
+ * Returns zero after adding a new daemon id to the hash list;
+ * non-zero otherwise.
+ */
+int ecryptfs_process_helo(unsigned int transport, uid_t uid, pid_t pid)
+{
+        struct ecryptfs_daemon_id *new_id;
+        struct ecryptfs_daemon_id *old_id;
+        int rc;
+
+        mutex_lock(&ecryptfs_daemon_id_hash_mux);
+        new_id = kmalloc(sizeof(*new_id), GFP_KERNEL);
+        if (!new_id) {
+                rc = -ENOMEM;
+                ecryptfs_printk(KERN_ERR, "Failed to allocate memory; unable "
+                                "to register daemon [%d] for user\n", pid, uid);
+                goto unlock;
+        }
+        if (!ecryptfs_find_daemon_id(uid, &old_id)) {
+                printk(KERN_WARNING "Received request from user [%d] "
+                       "to register daemon [%d]; unregistering daemon "
+                       "[%d]\n", uid, pid, old_id->pid);
+                hlist_del(&old_id->id_chain);
+                rc = ecryptfs_send_raw_message(transport, ECRYPTFS_NLMSG_QUIT,
+                                               old_id->pid);
+                if (rc)
+                        printk(KERN_WARNING "Failed to send QUIT "
+                               "message to daemon [%d]; rc = [%d]\n",
+                               old_id->pid, rc);
+                kfree(old_id);
+        }
+        new_id->uid = uid;
+        new_id->pid = pid;
+        hlist_add_head(&new_id->id_chain,
+                       &ecryptfs_daemon_id_hash[ecryptfs_uid_hash(uid)]);
+        rc = 0;
+unlock:
+        mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+        return rc;
+}
+
+/**
+ * ecryptfs_process_quit
+ * @uid: The user ID owner of the message
+ * @pid: The process ID for the userspace program that sent the
+ *       message
+ *
+ * Deletes the corresponding daemon id for the given uid and pid, if
+ * it is the registered that is requesting the deletion. Returns zero
+ * after deleting the desired daemon id; non-zero otherwise.
+ */
+int ecryptfs_process_quit(uid_t uid, pid_t pid)
+{
+        struct ecryptfs_daemon_id *id;
+        int rc;
+
+        mutex_lock(&ecryptfs_daemon_id_hash_mux);
+        if (ecryptfs_find_daemon_id(uid, &id)) {
+                rc = -EINVAL;
+                ecryptfs_printk(KERN_ERR, "Received request from user [%d] to "
+                                "unregister unrecognized daemon [%d]\n", uid,
+                                pid);
+                goto unlock;
+        }
+        if (id->pid != pid) {
+                rc = -EINVAL;
+                ecryptfs_printk(KERN_WARNING, "Received request from user [%d] "
+                                "with pid [%d] to unregister daemon [%d]\n",
+                                uid, pid, id->pid);
+                goto unlock;
+        }
+        hlist_del(&id->id_chain);
+        kfree(id);
+        rc = 0;
+unlock:
+        mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+        return rc;
+}
+
+/**
+ * ecryptfs_process_reponse
+ * @msg: The ecryptfs message received; the caller should sanity check
+ *       msg->data_len
+ * @pid: The process ID of the userspace application that sent the
+ *       message
+ * @seq: The sequence number of the message
+ *
+ * Processes a response message after sending a operation request to
+ * userspace. Returns zero upon delivery to desired context element;
+ * non-zero upon delivery failure or error.
+ */
+int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t uid,
+                              pid_t pid, u32 seq)
+{
+        struct ecryptfs_daemon_id *id;
+        struct ecryptfs_msg_ctx *msg_ctx;
+        int msg_size;
+        int rc;
+
+        if (msg->index >= ecryptfs_message_buf_len) {
+                rc = -EINVAL;
+                ecryptfs_printk(KERN_ERR, "Attempt to reference "
+                                "context buffer at index [%d]; maximum "
+                                "allowable is [%d]\n", msg->index,
+                                (ecryptfs_message_buf_len - 1));
+                goto out;
+        }
+        msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
+        mutex_lock(&msg_ctx->mux);
+        if (ecryptfs_find_daemon_id(msg_ctx->task->euid, &id)) {
+                rc = -EBADMSG;
+                ecryptfs_printk(KERN_WARNING, "User [%d] received a "
+                                "message response from process [%d] but does "
+                                "not have a registered daemon\n",
+                                msg_ctx->task->euid, pid);
+                goto wake_up;
+        }
+        if (msg_ctx->task->euid != uid) {
+                rc = -EBADMSG;
+                ecryptfs_printk(KERN_WARNING, "Received message from user "
+                                "[%d]; expected message from user [%d]\n",
+                                uid, msg_ctx->task->euid);
+                goto unlock;
+        }
+        if (id->pid != pid) {
+                rc = -EBADMSG;
+                ecryptfs_printk(KERN_ERR, "User [%d] received a "
+                                "message response from an unrecognized "
+                                "process [%d]\n", msg_ctx->task->euid, pid);
+                goto unlock;
+        }
+        if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
+                rc = -EINVAL;
+                ecryptfs_printk(KERN_WARNING, "Desired context element is not "
+                                "pending a response\n");
+                goto unlock;
+        } else if (msg_ctx->counter != seq) {
+                rc = -EINVAL;
+                ecryptfs_printk(KERN_WARNING, "Invalid message sequence; "
+                                "expected [%d]; received [%d]\n",
+                                msg_ctx->counter, seq);
+                goto unlock;
+        }
+        msg_size = sizeof(*msg) + msg->data_len;
+        msg_ctx->msg = kmalloc(msg_size, GFP_KERNEL);
+        if (!msg_ctx->msg) {
+                rc = -ENOMEM;
+                ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
+                goto unlock;
+        }
+        memcpy(msg_ctx->msg, msg, msg_size);
+        msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
+        rc = 0;
+wake_up:
+        wake_up_process(msg_ctx->task);
+unlock:
+        mutex_unlock(&msg_ctx->mux);
+out:
+        return rc;
+}
+
+/**
+ * ecryptfs_send_message
+ * @transport: The transport over which to send the message (i.e.,
+ *             netlink)
+ * @data: The data to send
+ * @data_len: The length of data
+ * @msg_ctx: The message context allocated for the send
+ */
+int ecryptfs_send_message(unsigned int transport, char *data, int data_len,
+                          struct ecryptfs_msg_ctx **msg_ctx)
+{
+        struct ecryptfs_daemon_id *id;
+        int rc;
+
+        mutex_lock(&ecryptfs_daemon_id_hash_mux);
+        if (ecryptfs_find_daemon_id(current->euid, &id)) {
+                mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+                rc = -ENOTCONN;
+                ecryptfs_printk(KERN_ERR, "User [%d] does not have a daemon "
+                                "registered\n", current->euid);
+                goto out;
+        }
+        mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+        mutex_lock(&ecryptfs_msg_ctx_lists_mux);
+        rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
+        if (rc) {
+                mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
+                ecryptfs_printk(KERN_WARNING, "Could not claim a free "
+                                "context element\n");
+                goto out;
+        }
+        ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
+        mutex_unlock(&(*msg_ctx)->mux);
+        mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
+        switch (transport) {
+        case ECRYPTFS_TRANSPORT_NETLINK:
+                rc = ecryptfs_send_netlink(data, data_len, *msg_ctx,
+                                           ECRYPTFS_NLMSG_REQUEST, 0, id->pid);
+                break;
+        case ECRYPTFS_TRANSPORT_CONNECTOR:
+        case ECRYPTFS_TRANSPORT_RELAYFS:
+        default:
+                rc = -ENOSYS;
+        }
+        if (rc) {
+                printk(KERN_ERR "Error attempting to send message to userspace "
+                       "daemon; rc = [%d]\n", rc);
+        }
+out:
+        return rc;
+}
+
+/**
+ * ecryptfs_wait_for_response
+ * @msg_ctx: The context that was assigned when sending a message
+ * @msg: The incoming message from userspace; not set if rc != 0
+ *
+ * Sleeps until awaken by ecryptfs_receive_message or until the amount
+ * of time exceeds ecryptfs_message_wait_timeout.  If zero is
+ * returned, msg will point to a valid message from userspace; a
+ * non-zero value is returned upon failure to receive a message or an
+ * error occurs.
+ */
+int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
+                               struct ecryptfs_message **msg)
+{
+        signed long timeout = ecryptfs_message_wait_timeout * HZ;
+        int rc = 0;
+
+sleep:
+        timeout = schedule_timeout_interruptible(timeout);
+        mutex_lock(&ecryptfs_msg_ctx_lists_mux);
+        mutex_lock(&msg_ctx->mux);
+        if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
+                if (timeout) {
+                        mutex_unlock(&msg_ctx->mux);
+                        mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
+                        goto sleep;
+                }
+                rc = -ENOMSG;
+        } else {
+                *msg = msg_ctx->msg;
+                msg_ctx->msg = NULL;
+        }
+        ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
+        mutex_unlock(&msg_ctx->mux);
+        mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
+        return rc;
+}
+
+int ecryptfs_init_messaging(unsigned int transport)
+{
+        int i;
+        int rc = 0;
+
+        if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
+                ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
+                ecryptfs_printk(KERN_WARNING, "Specified number of users is "
+                                "too large, defaulting to [%d] users\n",
+                                ecryptfs_number_of_users);
+        }
+        mutex_init(&ecryptfs_daemon_id_hash_mux);
+        mutex_lock(&ecryptfs_daemon_id_hash_mux);
+        ecryptfs_hash_buckets = 0;
+        while (ecryptfs_number_of_users >> ++ecryptfs_hash_buckets);
+        ecryptfs_daemon_id_hash = kmalloc(sizeof(struct hlist_head)
+                                          * ecryptfs_hash_buckets, GFP_KERNEL);
+        if (!ecryptfs_daemon_id_hash) {
+                rc = -ENOMEM;
+                ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
+                goto out;
+        }
+        for (i = 0; i < ecryptfs_hash_buckets; i++)
+                INIT_HLIST_HEAD(&ecryptfs_daemon_id_hash[i]);
+        mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+
+        ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
+                                      * ecryptfs_message_buf_len), GFP_KERNEL);
+        if (!ecryptfs_msg_ctx_arr) {
+                rc = -ENOMEM;
+                ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
+                goto out;
+        }
+        mutex_init(&ecryptfs_msg_ctx_lists_mux);
+        mutex_lock(&ecryptfs_msg_ctx_lists_mux);
+        ecryptfs_msg_counter = 0;
+        for (i = 0; i < ecryptfs_message_buf_len; i++) {
+                INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
+                mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
+                mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
+                ecryptfs_msg_ctx_arr[i].index = i;
+                ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
+                ecryptfs_msg_ctx_arr[i].counter = 0;
+                ecryptfs_msg_ctx_arr[i].task = NULL;
+                ecryptfs_msg_ctx_arr[i].msg = NULL;
+                list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
+                              &ecryptfs_msg_ctx_free_list);
+                mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
+        }
+        mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
+        switch(transport) {
+        case ECRYPTFS_TRANSPORT_NETLINK:
+                rc = ecryptfs_init_netlink();
+                if (rc)
+                        ecryptfs_release_messaging(transport);
+                break;
+        case ECRYPTFS_TRANSPORT_CONNECTOR:
+        case ECRYPTFS_TRANSPORT_RELAYFS:
+        default:
+                rc = -ENOSYS;
+        }
+out:
+        return rc;
+}
+
+void ecryptfs_release_messaging(unsigned int transport)
+{
+        if (ecryptfs_msg_ctx_arr) {
+                int i;
+
+                mutex_lock(&ecryptfs_msg_ctx_lists_mux);
+                for (i = 0; i < ecryptfs_message_buf_len; i++) {
+                        mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
+                        if (ecryptfs_msg_ctx_arr[i].msg)
+                                kfree(ecryptfs_msg_ctx_arr[i].msg);
+                        mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
+                }
+                kfree(ecryptfs_msg_ctx_arr);
+                mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
+        }
+        if (ecryptfs_daemon_id_hash) {
+                struct hlist_node *elem;
+                struct ecryptfs_daemon_id *id;
+                int i;
+
+                mutex_lock(&ecryptfs_daemon_id_hash_mux);
+                for (i = 0; i < ecryptfs_hash_buckets; i++) {
+                        hlist_for_each_entry(id, elem,
+                                             &ecryptfs_daemon_id_hash[i],
+                                             id_chain) {
+                                hlist_del(elem);
+                                kfree(id);
+                        }
+                }
+                kfree(ecryptfs_daemon_id_hash);
+                mutex_unlock(&ecryptfs_daemon_id_hash_mux);
+        }
+        switch(transport) {
+        case ECRYPTFS_TRANSPORT_NETLINK:
+                ecryptfs_release_netlink();
+                break;
+        case ECRYPTFS_TRANSPORT_CONNECTOR:
+        case ECRYPTFS_TRANSPORT_RELAYFS:
+        default:
+                break;
+        }
+        return;
+}