Plumb connect_session call into sesman and sesexec

sesman/scp_process.c

@@ -31,6 +31,7 @@
 #include "trans.h"
 #include "os_calls.h"
 #include "eicp.h"
+#include "ercp.h"
 #include "scp.h"
 
 #include "display_utils.h"
@@ -301,9 +302,12 @@ logout_scp_list_item(struct scp_list_item *sli)
 {
     if (sli->login_state != E_SLI_LOGIN_NOT_LOGGED_IN)
     {
-        (void)eicp_send_logout_request(sli->sesexec_trans);
+        if (sli->sesexec_trans != NULL)
-        trans_delete(sli->sesexec_trans);
+        {
-        sli->sesexec_trans = NULL;
+            (void)eicp_send_logout_request(sli->sesexec_trans);
+            trans_delete(sli->sesexec_trans);
+            sli->sesexec_trans = NULL;
+        }
         sli->uid = (uid_t) -1;
         g_free(sli->username);
         sli->username = NULL;
@@ -469,6 +473,9 @@ process_create_session_request(struct scp_list_item *sli)
             if (s_item != NULL)
             {
                 // Found an existing session
+                LOG(LOG_LEVEL_INFO,
+                    "A suitable session on display :%d is already active",
+                    s_item->display);
                 display = s_item->display;
                 guid = s_item->guid;
             }
@@ -476,15 +483,22 @@ process_create_session_request(struct scp_list_item *sli)
             else if (g_cfg->sess.max_sessions > 0 &&
                      session_list_get_count() >= g_cfg->sess.max_sessions)
             {
+                LOG(LOG_LEVEL_ERROR,
+                    "The maximum number of sessions has been reached");
                 status = E_SCP_SCREATE_MAX_REACHED;
             }
             else if ((display = get_free_display()) < 0)
             {
+                LOG(LOG_LEVEL_ERROR,
+                    "No free display can be found for a new session");
                 status = E_SCP_SCREATE_NO_DISPLAY;
             }
             // Create a socket dir for this user
             else if (create_xrdp_socket_path(sli->uid) != 0)
             {
+                LOG(LOG_LEVEL_ERROR,
+                    "Can't create a socket directory for UID %d",
+                    (int)sli->uid);
                 status = E_SCP_SCREATE_GENERAL_ERROR;
             }
             // Create a sesexec process if we don't have one (UDS login)
@@ -511,6 +525,8 @@ process_create_session_request(struct scp_list_item *sli)
             else
             {
                 // Pass the session create request to sesexec
+                LOG(LOG_LEVEL_INFO,
+                    "Passing session creation request to sesexec");
                 int eicp_stat;
                 eicp_stat = eicp_send_create_session_request(
                                 sli->sesexec_trans,
@@ -554,6 +570,86 @@ process_create_session_request(struct scp_list_item *sli)
 
 /******************************************************************************/
 
+static int
+process_connect_session_request(struct scp_list_item *sli)
+{
+    int rv;
+    /* Client parameters describing new session */
+    struct guid guid;
+    unsigned int flags;
+    enum scp_sconnect_status status = E_SCP_SCONNECT_OK;
+
+    rv = scp_get_connect_session_request(sli->client_trans, &guid, &flags);
+
+    if (rv == 0)
+    {
+        if (sli->login_state == E_SLI_LOGIN_NOT_LOGGED_IN)
+        {
+            status = E_SCP_SCONNECT_NOT_LOGGED_IN;
+        }
+        else
+        {
+            struct session_item *s_item = session_list_get_byguid(&guid);
+            if (s_item == NULL)
+            {
+                LOG(LOG_LEVEL_ERROR,
+                    "User %s tried to connect to non-existent session",
+                    sli->username);
+                status = E_SCP_SCONNECT_NO_SUCH_GUID;
+            }
+            else if (s_item->uid != sli->uid)
+            {
+                LOG(LOG_LEVEL_ERROR,
+                    "User %s (UID %d) denied access to session for UID %d",
+                    sli->username, sli->uid, s_item->uid);
+                status = E_SCP_SCONNECT_NO_SUCH_GUID;
+            }
+            else
+            {
+                // Don't log the GUID
+                LOG(LOG_LEVEL_INFO,
+                    "Forwarding request from %s to connect to a session",
+                    sli->username);
+                // Pass the session create request to sesexec
+                int ercp_stat;
+                ercp_stat = ercp_send_connect_session_request(
+                                s_item->sesexec_trans,
+                                sli->client_trans->sck,
+                                flags);
+
+                if (ercp_stat != 0)
+                {
+                    // The sesexec transport is broken. That's dealt with
+                    // elsewhere.
+                    LOG(LOG_LEVEL_ERROR,
+                        "Can't ask sesexec to connect to a session");
+                    status = E_SCP_SCONNECT_GENERAL_ERROR;
+                }
+                else
+                {
+                    status = E_SCP_SCONNECT_OK;
+                }
+            }
+        }
+
+        // Send anything other than a successful connection request
+        // back to the client
+        if (status != E_SCP_SCONNECT_OK)
+        {
+            rv = scp_send_connect_session_response(sli->client_trans,
+                                                   status, -1, -1);
+        }
+    }
+
+    // This call is always the last thing on the SCP connection.
+    logout_scp_list_item(sli); // Remove any sesexec process used for auth
+    sli->dispatcher_action = E_SLD_TERMINATE_SCP_CONN;
+
+    return rv;
+}
+
+/******************************************************************************/
+
 static int
 process_list_sessions_request(struct scp_list_item *sli)
 {
@@ -639,6 +735,12 @@ process_close_connection_request(struct scp_list_item *sli)
     LOG(LOG_LEVEL_INFO, "Received request to close connection from %s",
         sli->peername);
 
+    /* Make sure we're logged out */
+    if (sli->login_state != E_SLI_LOGIN_NOT_LOGGED_IN)
+    {
+        logout_scp_list_item(sli);
+    }
+
     /* Expecting no more client messages. Close the connection
      * after returning from this callback */
     sli->dispatcher_action = E_SLD_TERMINATE_SCP_CONN;
@@ -674,6 +776,10 @@ scp_process(struct scp_list_item *sli)
             rv = process_create_session_request(sli);
             break;
 
+        case E_SCP_CONNECT_SESSION_REQUEST:
+            rv = process_connect_session_request(sli);
+            break;
+
         case E_SCP_LIST_SESSIONS_REQUEST:
             rv = process_list_sessions_request(sli);
             break;

sesman/sesexec/ercp_server.c

@@ -30,7 +30,10 @@
 
 #include "arch.h"
 
+#include "login_info.h"
+#include "scp.h"
 #include "sesexec.h"
+#include "os_calls.h"
 #include "session.h"
 #include "trans.h"
 
@@ -38,11 +41,99 @@
 #include "ercp_server.h"
 
 /******************************************************************************/
-static int
+static enum scp_sconnect_status
-handle_session_reconnect_event(struct trans *self)
+get_session_fds(struct session_data *sd, unsigned int scp_flags,
+                int *display_fd, int *chan_fd)
 {
-    session_reconnect(g_login_info, g_session_data);
+    enum scp_sconnect_status result = E_SCP_SCONNECT_OK;
-    return 0;
+
+    if ((*display_fd = session_get_display_server_fd(g_login_info, sd)) < 0)
+    {
+        result = E_SCP_SCONNECT_SERVER_FAIL;
+    }
+    else if ((scp_flags & E_SCP_SCONNECT_FLAG_NEED_CHANSRV) == 0)
+    {
+        // Don't need to try to connect to chansrv
+        *chan_fd = -1;
+    }
+    else
+    {
+        // If this fails, it's inconvenient, but not a show-stopper
+        *chan_fd = session_get_chansrv_fd(g_login_info, sd);
+    }
+
+    return result;
+}
+
+/******************************************************************************/
+static int
+handle_connect_session_request(struct trans *self)
+{
+    int scp_fd = -1;
+    unsigned int scp_flags;
+
+    int rv = ercp_get_connect_session_request(self, &scp_fd, &scp_flags);
+    if (rv == 0)
+    {
+        struct trans *scp_trans;
+
+        if ((scp_trans = scp_init_trans_from_fd(scp_fd,
+                                                TRANS_TYPE_SERVER,
+                                                sesexec_is_term)) == NULL)
+        {
+            LOG(LOG_LEVEL_ERROR, "Can't create SCP trans");
+            rv = 1;
+        }
+        else
+        {
+            scp_fd = -1; // Don't close this twice!
+
+            // Now we've got a transport we can send data back to
+            // the SCP client
+            enum scp_sconnect_status scp_status;
+            int display_fd = -1;
+            int chan_fd = -1;
+            scp_status = get_session_fds(g_session_data, scp_flags,
+                                         &display_fd, &chan_fd);
+            rv = scp_send_connect_session_response(scp_trans, scp_status,
+                                                   display_fd, chan_fd);
+
+            if (rv == 0 && scp_status == E_SCP_SCONNECT_OK)
+            {
+                // Don't run the reconnect script on the first connect
+                if (session_increment_connect_count(g_session_data) == 0)
+                {
+                    LOG(LOG_LEVEL_INFO, "User %s has connected to a session",
+                        g_login_info->username);
+                }
+                else
+                {
+                    LOG(LOG_LEVEL_INFO, "User %s has reconnected to a session",
+                        g_login_info->username);
+                    session_run_reconnect_script(g_login_info, g_session_data);
+                }
+            }
+
+            // Regardless of the result of the send, we must close all
+            // our copies of file descriptors.
+            if (display_fd >= 0)
+            {
+                g_file_close(display_fd);
+            }
+            if (chan_fd >= 0)
+            {
+                g_file_close(chan_fd);
+            }
+            trans_delete(scp_trans);
+        }
+    }
+
+    if (scp_fd >= 0)
+    {
+        g_file_close(scp_fd);
+    }
+
+    return rv;
 }
 
 /******************************************************************************/
@@ -54,8 +145,8 @@ ercp_server(struct trans *self)
 
     switch ((msgno = ercp_msg_in_get_msgno(self)))
     {
-        case E_ERCP_SESSION_RECONNECT_EVENT:
+        case E_ERCP_CONNECT_SESSION_REQUEST:
-            rv = handle_session_reconnect_event(self);
+            rv = handle_connect_session_request(self);
             break;
 
         default:

sesman/sesexec/session.c

@@ -33,6 +33,7 @@
 #include "config_ac.h"
 #endif
 
+#include <stdio.h>
 #include <errno.h>
 
 #include "arch.h"
@@ -49,6 +50,7 @@
 #include "sesexec.h"
 #include "sessionrecord.h"
 #include "string_calls.h"
+#include "trans.h"
 #include "xauth.h"
 #include "xwait.h"
 #include "xrdp_sockets.h"
@@ -59,6 +61,7 @@ struct session_data
     pid_t win_mgr; ///< PID of window manager
     pid_t chansrv; //< PID of chansrv
     time_t start_time;
+    unsigned int connect_count;
     struct session_parameters params;
     // Flexible array member used to store strings in params and ip_addr;
 #ifdef __cplusplus
@@ -95,6 +98,7 @@ session_data_new(const struct session_parameters *sp)
         sd->x_server = -1;
         sd->chansrv = -1;
         sd->start_time = 0;
+        sd->connect_count = 0;
 
         /* Copy all the non-string session parameters... */
         sd->params = *sp;
@@ -184,7 +188,7 @@ dumpItemsToString(struct list *self, char *outstr, int len)
 
 /******************************************************************************/
 static void
-start_chansrv(struct login_info *login_info,
+start_chansrv(const struct login_info *login_info,
               const struct session_parameters *s)
 {
     struct list *chansrv_params = list_create();
@@ -222,7 +226,7 @@ start_chansrv(struct login_info *login_info,
 
 /******************************************************************************/
 static void
-start_window_manager(struct login_info *login_info,
+start_window_manager(const struct login_info *login_info,
                      const struct session_parameters *s)
 {
     char text[256];
@@ -471,7 +475,7 @@ prepare_xvnc_xserver_params(const struct session_parameters *s,
 /******************************************************************************/
 /* Either execs the X server, or returns */
 static void
-start_x_server(struct login_info *login_info,
+start_x_server(const struct login_info *login_info,
                const struct session_parameters *s)
 {
     char authfile[256]; /* The filename for storing xauth information */
@@ -575,8 +579,8 @@ start_x_server(struct login_info *login_info,
  * Simple helper process to fork a child and log errors */
 static int
 fork_child(
-    void (*runproc)(struct login_info *, const struct session_parameters *),
+    void (*runproc)(const struct login_info *, const struct session_parameters *),
-    struct login_info *login_info,
+    const struct login_info *login_info,
     const struct session_parameters *s,
     pid_t group_pid)
 {
@@ -1065,6 +1069,20 @@ session_get_start_time(const struct session_data *sd)
     return (sd == NULL) ? 0 : sd->start_time;
 }
 
+/******************************************************************************/
+unsigned int
+session_get_connect_count(const struct session_data *sd)
+{
+    return (sd == NULL) ? 0 : sd->connect_count;
+}
+
+/******************************************************************************/
+unsigned int
+session_increment_connect_count(struct session_data *sd)
+{
+    return (sd == NULL) ? 0 : sd->connect_count++;
+}
+
 /******************************************************************************/
 const struct session_parameters *
 session_get_parameters(const struct session_data *sd)
@@ -1110,7 +1128,7 @@ session_send_term(struct session_data *sd, int wait_for_all)
 
 /******************************************************************************/
 static void
-start_reconnect_script(struct login_info *login_info,
+start_reconnect_script(const struct login_info *login_info,
                        const struct session_parameters *s)
 {
     env_set_user(login_info->uid, 0, s->display,
@@ -1143,8 +1161,8 @@ start_reconnect_script(struct login_info *login_info,
 
 /******************************************************************************/
 void
-session_reconnect(struct login_info *login_info,
+session_run_reconnect_script(const struct login_info *login_info,
-                  struct session_data *sd)
+                             const struct session_data *sd)
 {
     if (fork_child(start_reconnect_script,
                    login_info, &sd->params, sd->x_server) < 0)
@@ -1152,3 +1170,113 @@ session_reconnect(struct login_info *login_info,
         LOG(LOG_LEVEL_ERROR, "Failed to fork for session reconnection script");
     }
 }
+
+/******************************************************************************/
+int
+session_get_display_server_fd(const struct login_info *login_info,
+                              const struct session_data *sd)
+{
+    char portname[XRDP_SOCKETS_MAXPATH];
+    const char *localhost = "localhost"; // Ignored for TRANS_MODE_UNIX
+    int socket_mode;
+
+    int rv = -1;
+
+    if (sd->x_server <= 0)
+    {
+        LOG(LOG_LEVEL_ERROR,
+            "Request to connect to display server :%u"
+            " which has exited", sd->params.display);
+    }
+    else
+    {
+        switch (sd->params.type)
+        {
+            case SCP_SESSION_TYPE_XVNC:
+                socket_mode = TRANS_MODE_TCP;
+                snprintf(portname, sizeof(portname), "%u",
+                         5900 + sd->params.display);
+                break;
+
+            case SCP_SESSION_TYPE_XVNC_UDS:
+            case SCP_SESSION_TYPE_XORG:
+                socket_mode = TRANS_MODE_UNIX;
+                snprintf(portname, sizeof(portname), XRDP_X11RDP_STR,
+                         login_info->uid, (int)sd->params.display);
+
+                break;
+
+            default:
+                LOG(LOG_LEVEL_ERROR, "Unsupported session type %d for connect",
+                    sd->params.type);
+                portname[0] = '\0';
+        }
+
+        if (portname[0] != '\0')
+        {
+            // Use the transport library to get the fd
+            struct trans *t = trans_create(socket_mode, 8 * 8192, 8192);
+            if (t == NULL)
+            {
+                LOG(LOG_LEVEL_ERROR, "Out of memory creating transport");
+            }
+            else if (trans_connect(t, localhost, portname, 3000) != 0)
+            {
+                LOG(LOG_LEVEL_ERROR, "Can't connect to display server :%u [%s]",
+                    sd->params.display,
+                    g_get_strerror());
+            }
+            else
+            {
+                rv = t->sck;
+                t->sck = -1;
+            }
+            trans_delete(t);
+        }
+    }
+
+    return rv;
+}
+
+/******************************************************************************/
+int
+session_get_chansrv_fd(const struct login_info *login_info,
+                       const struct session_data *sd)
+{
+    char portname[XRDP_SOCKETS_MAXPATH];
+
+    int rv = -1;
+
+    if (sd->chansrv <= 0)
+    {
+        LOG(LOG_LEVEL_ERROR,
+            "Request to connect to chansrv :%u"
+            " which has exited", sd->params.display);
+    }
+    else
+    {
+        snprintf(portname, sizeof(portname),
+                 XRDP_CHANSRV_STR, login_info->uid, (int)sd->params.display);
+
+        // Use the transport library to get the fd
+        struct trans *t = trans_create(TRANS_MODE_UNIX, 8192, 8192);
+        if (t == NULL)
+        {
+            LOG(LOG_LEVEL_ERROR, "Out of memory creating transport");
+        }
+        else if (trans_connect(t, NULL, portname, 10 * 1000) != 0)
+        {
+            LOG(LOG_LEVEL_ERROR, "Can't connect to chansrv :%u [%s]",
+                sd->params.display,
+                g_get_strerror());
+        }
+        else
+        {
+            rv = t->sck;
+            t->sck = -1;
+        }
+        trans_delete(t);
+    }
+
+    return rv;
+}

sesman/sesexec/session.h

@@ -108,6 +108,22 @@ session_active(const struct session_data *sd);
 time_t
 session_get_start_time(const struct session_data *sd);
 
+/**
+ * Returns the connect count for an active session
+ * @param sd session_data for this session
+ * @return connect count
+ */
+unsigned int
+session_get_connect_count(const struct session_data *sd);
+
+/**
+ * Increment the connect count for an active session
+ * @param sd session_data for this session
+ * @return Pre-increment value of the connect count
+ */
+unsigned int
+session_increment_connect_count(struct session_data *sd);
+
 /**
  * Returns the parameters used to start the session
  *
@@ -145,7 +161,21 @@ session_data_free(struct session_data *session_data);
  * Runs the reconnect script for the session
  */
 void
-session_reconnect(struct login_info *login_info,
+session_run_reconnect_script(const struct login_info *login_info,
-                  struct session_data *sd);
+                             const struct session_data *sd);
+
+/**
+ * Connects a file descriptor to the display server
+ */
+int
+session_get_display_server_fd(const struct login_info *login_info,
+                              const struct session_data *sd);
+
+/**
+ * Connects a file descriptor to chansrv
+ */
+int
+session_get_chansrv_fd(const struct login_info *login_info,
+                       const struct session_data *sd);
 
 #endif // SESSION_H

sesman/session_list.c

@@ -361,6 +361,25 @@ session_list_get_byuid(const uid_t *uid, unsigned int *cnt, unsigned int flags)
     return sess;
 }
 
+/******************************************************************************/
+struct session_item *
+session_list_get_byguid(const struct guid *guid)
+{
+    int i;
+
+    for (i = 0 ; i < g_session_list->count ; ++i)
+    {
+        struct session_item *si;
+        si = (struct session_item *)list_get_item(g_session_list, i);
+        if (SESSION_IN_USE(si) && GUID_ARE_EQUAL(guid, &si->guid))
+        {
+            return si;
+        }
+    }
+
+    return NULL;
+}
+
 /******************************************************************************/
 void
 free_session_info_list(struct scp_session_info *sesslist, unsigned int cnt)

sesman/session_list.h

@@ -153,6 +153,17 @@ session_list_get_bydata(uid_t uid,
 struct scp_session_info *
 session_list_get_byuid(const uid_t *uid, unsigned int *cnt, unsigned int flags);
 
+/**
+ * @brief retrieves a session by GUID
+ * @param guid GUID of session
+ * @return Pointer to session, or NULL.
+ *
+ * The caller is responsible for checking the client has
+ * permissions to access the session.
+ */
+struct session_item *
+session_list_get_byguid(const struct guid *guid);
+
 /**
  *
  * @brief Frees the result of session_get_byuser()