On 29/12/2023 15:07, Chang, Abner via groups.io wrote:
To locate TLS protocol from the HTTP handle and configure TLS configuration
data at the return from EfiHttpRequest during that short window of non-blocking
request is not reliable. It also doesn't make sense to ask upper layer
application to do this when it first time invokes EfiHttpRequest.
I already refactored TlsCreateChild to install TLS protocol on HTTP handle. I
also implemented the corresponding code in Redfish REST EX to listen the
installation of TLS protocol and hook the SetSessionData. It works fine on the
system, however I really don’t like having the upper layer application to do
this much just for overriding TLS configuration data. The code looked a
specific implementation to hack the TLS protocol interface. Plus I still have
to add few code in TlsConfigCertificate to skip configure certificate with
checking TlsVerifyMethod.
We should sit back to consider introducing a new protocol for upper layer
application to provide their own TLS configuration data, as the root cause is
that hard coded TLS configuration data in HttpSupport.c. We shouldn't have the
code like that and add the burdens to application.
What my thought is as below and maybe more elegant than the patch a sent,
- Still install TLS on HTTP handle, then upper layer application can listen to
the installation of EFI TLS protocol to find the correct HTTP handle.
- Move TLS_CONFIG_DATA in a public header file.
- Introduce a new protocol called EDKII_HTTP_TLS_CONFIGURATION_DATA
- Upper layer application installs this protocol with their own TLS_CONFIG_DATA.
- TlsConfigureSession locates EDKII_HTTP_TLS_CONFIGURATION_DATA to replace the
default TLS_CONFIG_DATA.
This way we can remove that hardcoded code and fix the root cause, also the
upper layer application do not have to take the burden.
What do you think?
Firstly, thank you very much for taking the time to dig through this and
work towards a cleaner design - I, for one, really appreciate it.
I think we're completely agreed that installing the TLS protocols on the
HTTP handle is the right thing to do - that seems to be a clear
improvement over the status quo where there's no introspectable
relationship between the two handles.
I'm torn on the use of TLS_CONFIG_DATA. For better or worse, the
existing and standardised EFI_TLS_CONFIGURATION_PROTOCOL is verb-based,
using SetData() and GetData() methods. Adding a noun-based protocol for
TLS configuration seems to cut across this, with the potential to look
confusing: a new reader of the code could legitimately wonder why the
codebase contains two competing solutions to what is essentially the
same problem.
Given that the verb-based approach of EFI_TLS_CONFIGURATION_PROTOCOL has
made it as far as being standardised and included in the UEFI
specification, I think we probably need to accept that this is the
"correct" way to perform TLS configuration within UEFI code. The
problem with HttpsSupport.c then becomes that there is no good
opportunity for a consumer to call SetData(), since (a)
EFI_TLS_CONFIGURATION_PROTOCOL comes into existence only halfway through
the call to EFI_HTTP_PROTOCOL.Request() and (b) the call to
TlsConfigureSession() will overwrite the configuration anyway.
Is there a way that TlsConfigureSession() could sensibly provide an
opportunity for the consumer to make calls to SetData(), so that the
consumer could cleanly override any default configuration?
Looking through the code, TlsConfigureSession() is called only from
HttpInitSession(), which in turn is called only from EfiHttpRequest().
This call is followed immediately by the line:
HttpNotify (HttpEventInitSession, Status);
which seems to already use an existing EDKII_HTTP_CALLBACK_PROTOCOL to
notify an arbitrary list of interested consumers that an event has taken
place (in this case, that a session has just been initialised).
What do you think about:
- installing TLS on HTTP handle (as you have already implemented)
- using EDKII_HTTP_CALLBACK_PROTOCOL to catch the HttpEventInitSession
and perform whatever calls are needed to SetData() to modify the TLS
configuration?
Thanks,
Michael
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