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Re: [libvirt] [PATCH] remote: Forbid default "/session" connections when using ssh transport



On 06/12/13 21:34, Laine Stump wrote:
On 06/10/2013 08:44 AM, Peter Krempa wrote:


Can you include in the commit log a link to the BZ describing this
problem? It helps *immensely* when trying to trace things months/years
later.


There isn't any publicly available BZ describing this problem so I chose not to put the private link in the commit. I can do it if you insist but having private links in a public repo doesn't seem right to me.


Without the socket path explicitly specified, the remote driver tried to
connect to the "/system" instance socket even if "/session" was
specified in the uri. With this patch this configuration now produces an
error.

It is still possible to initiate a session connection with specifying
the path to the socket manually and also manually starting the session
daemon. This was also possible prior to this patch,

This is a minimal fix. We may decide to support remote session
connections using ssh but this will require changes to the remote driver
code so this fix shouldn't cause regressions in the case we decide to do
that.
---
  src/remote/remote_driver.c | 40 ++++++++++++++++++++++++++++++----------
  1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/src/remote/remote_driver.c b/src/remote/remote_driver.c
index fcf45d3..bd5646a 100644
--- a/src/remote/remote_driver.c
+++ b/src/remote/remote_driver.c
@@ -631,11 +631,21 @@ doRemoteOpen(virConnectPtr conn,
          break;

      case trans_libssh2:
-        if (!sockname &&
-            VIR_STRDUP(sockname,
-                       flags & VIR_DRV_OPEN_REMOTE_RO ?
-                       LIBVIRTD_PRIV_UNIX_SOCKET_RO : LIBVIRTD_PRIV_UNIX_SOCKET) < 0)
-            goto failed;
+        if (!sockname) {
+            /* Right now we don't support default session connections */
+            if (STREQ(conn->uri->path, "/session")) {
+                virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                               _("Connecting to session instance without "
+                                 "socket path is not supported by the libssh2 "
+                                 "connection driver"));
+                goto failed;
+            }

A totally naive question: do we want to only allow "/system"? or
'anything except "/session"'?

We want to forbid only "/session" with the default socket path which won't work right now. A user is able to start a session daemon and successfully connect to it even with this patch. The user has to manually specify a socket path.

Rejecting everything except "/system" would break drivers that use different path. A (stupid) example:

$ virsh -c test+ssh://root localhost/default
Welcome to virsh, the virtualization interactive terminal.

Type:  'help' for help with commands
       'quit' to quit

virsh # list --all
 Id    Name                           State
----------------------------------------------------
 1     test                           running



+
+            if (VIR_STRDUP(sockname,
+                           flags & VIR_DRV_OPEN_REMOTE_RO ?
+                           LIBVIRTD_PRIV_UNIX_SOCKET_RO : LIBVIRTD_PRIV_UNIX_SOCKET) < 0)
+                goto failed;
+        }

          VIR_DEBUG("Starting LibSSH2 session");

@@ -698,11 +708,21 @@ doRemoteOpen(virConnectPtr conn,
          if (!command && VIR_STRDUP(command, "ssh") < 0)
              goto failed;

-        if (!sockname &&
-            VIR_STRDUP(sockname,
-                       flags & VIR_DRV_OPEN_REMOTE_RO ?
-                       LIBVIRTD_PRIV_UNIX_SOCKET_RO : LIBVIRTD_PRIV_UNIX_SOCKET) < 0)
-            goto failed;
+        if (!sockname) {
+            /* Right now we don't support default session connections */
+            if (STREQ(conn->uri->path, "/session")) {
+                virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                               _("Connecting to session instance without "
+                                 "socket path is not supported by the ssh "
+                                 "connection driver"));
+                goto failed;
+            }
+
+            if (VIR_STRDUP(sockname,
+                           flags & VIR_DRV_OPEN_REMOTE_RO ?
+                           LIBVIRTD_PRIV_UNIX_SOCKET_RO : LIBVIRTD_PRIV_UNIX_SOCKET) < 0)
+                goto failed;
+        }

          if (!(priv->client = virNetClientNewSSH(priv->hostname,
                                                  port,

ACK once the BZ link is included in the commit log (and pending my
question about whether we want to check for == "/session" or != "/system").


Peter


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