Re: [libvirt] [PATCH 1/2] util: Add possibility to call virAuthGetPassword without conn object

On Tue, Nov 27, 2012 at 04:38:49PM +0100, Peter Krempa wrote: > On 11/27/12 15:56, Daniel P. Berrange wrote: >> On Tue, Nov 27, 2012 at 02:55:11PM +0000, Daniel P. Berrange wrote: >>> On Tue, Nov 27, 2012 at 03:39:16PM +0100, Peter Krempa wrote: >>>> To make this function callable from code that doesn't have the conn >>>> object, call the conn-dependant code only if conn was provided. >>>> --- >>>> src/util/virauth.c | 13 ++++++++----- >>>> 1 file changed, 8 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/src/util/virauth.c b/src/util/virauth.c >>>> index 6d9935d..738b3c5 100644 >>>> --- a/src/util/virauth.c >>>> +++ b/src/util/virauth.c >>>> @@ -205,7 +205,8 @@ virAuthGetUsername(virConnectPtr conn, >>>> } >>>> >>>> >>>> - >>>> +/* if this function is called with conn == NULL, the code requesting >>>> + * the password from the config file is skipped */ >>>> char * >>>> virAuthGetPassword(virConnectPtr conn, >>>> virConnectAuthPtr auth, >>>> @@ -218,10 +219,12 @@ virAuthGetPassword(virConnectPtr conn, >>>> char *prompt; >>>> char *ret = NULL; >>>> >>>> - if (virAuthGetCredential(conn, servicename, "password", &ret) < 0) >>>> - return NULL; >>>> - if (ret != NULL) >>>> - return ret; >>>> + if (conn) { >>>> + if (virAuthGetCredential(conn, servicename, "password", &ret) < 0) >>>> + return NULL; >>>> + if (ret != NULL) >>>> + return ret; >>>> + } >>>> >>>> memset(&cred, 0, sizeof(virConnectCredential)); >>> >>> NACK, I don't think this is right. The libssh2 code that is using this >>> must have a virConnectPtr instance somewhere in its callstack. We > > The connection object is available in the doRemoteOpen function in > the remote driver and it might be passed further down through the > virNetClient and virNetSocket objects until it reaches pure libssh2 > transport code. > >>> should fix the code to pass the connection in where needed, not skip >>> this. > > This might be needed but right now the credential storage option is > not desired. The original keyboard-interactive implementation has to > ask the user for various arbitrary challenges that are provided by > the server. The virAuth implementation does not allow this. I'm not sure I agree with you there - the SASL code also has the ability to ask the user for arbitrary challenges, and we support that with the virAuth already. See the method remoteAuthFillFromConfig in remote_driver.c The virNetSSHKbIntCb method could be made to lookup the credentials in the auth config file in a similar manner. > The code provided in patch 2/2 is adding fallback method to do the > authentication with passwords when keyboard interactive is not > available. When the user will be able to store the passwords in the > auth file, this will introduce dual behavior on hosts supporting > keyboard interactive auth where the user won't be able to store the > password as the challenge is provided by the remote server and > virauth does not support getting arbitrary requests from the user. > On hosts that don't support this, the user would be able to save > passwords. > > With that change the fallback behavior wouldn't be desired. We might > change the default authentication method to be password and leave > keyboard-interactive for really special scenarios that wouldn't > support storing the credentials. (This at the cost of polluting > virNetClient and virNetSocket with the connection object (or the > URI) and even more added code). Looking at the code, in the keyboard-interactive method, you call a libssh2 API, which in turn calls virNetSSHKbIntCb() to fill up a libvirt virConnectCredentialPtr struct with prompts. In this new patch, you are using the virAuthGetPassword function as a way to fill a virConnectCredentialPtr with prompts. I'd be inclined to say the new patch should just directly call virNetSSHKbIntCb to do this and avoid touching virAuthGetPassword at all.

Daniel