fix: Verify authentication independent of packet msg flags #496
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Signed-off-by: Sven Rebhan <srebhan@influxdata.com>
Signed-off-by: Sven Rebhan <srebhan@influxdata.com>
Signed-off-by: Sven Rebhan <srebhan@influxdata.com>
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@SuperQ is there a chance to get a review on this security related PR? |
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Fixed the remaining test so this should be good to review... Anyone? |
Signed-off-by: Sven Rebhan <srebhan@influxdata.com>
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soniah
approved these changes
Apr 15, 2025
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In the current state, a
TrapListenerconfigured with authentication (e.g.AuthNoPriv) will accept all incoming packets sent without authentication enabled e.g. viaThis is due to the fact that the
isAuthenticfunction will only iterate over the authentication parameters sent by the client, which is empty forNoAuthNoPriv, and therefore completely ignores the authentication settings for theTrapListenerand potentially for other uses of the USM implementation. Furthermore, the username is not validated in case we do not use aTrapSecurityParametersTable.The current behavior therefore is a security issue as a client can simply bypass security of the server by sending unauthenticated messages!
This PR ensures that we always respect the server security settings by fully matching the message signature against the expected digest. The PR here uses cryptographically safe functions with constant time to avoid side-channel attacks.
Additionally, the username is always validated.
Last but not least, exclude discovery messages from authentication handling as they MUST be unauthenticated. Handle this special case.