tpm2: Add initial Connection.ResetDictionaryAttackLock APIs#512
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chrisccoulson wants to merge 1 commit intocanonical:masterfrom
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tpm2: Add initial Connection.ResetDictionaryAttackLock APIs#512chrisccoulson wants to merge 1 commit intocanonical:masterfrom
chrisccoulson wants to merge 1 commit intocanonical:masterfrom
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This adds initial APIs for resetting the TPM's dictionary attack counter to replace the direct use of go-tpm2's TPMContext.DictionaryAttackLockReset API. This doesn't yet include the changes to Connection.EnsureProvisioned which will create the authorization data that will be persisted by snapd and passed to this new API - this is coming in a follow-up PR. This is split into 2 APIs: - Connection.ResetDictionaryAttackLock which will be supplied with data that will be provided by an updated EnsureProvisioned API. - Connection.ResetDictionaryAttackLockWithAuthValue which will be supplied with a plain authorization value, previously chosen by snapd and provided to the current EnsureProvisioned API. I did think about having this as 1 API, and handling the case where decoding of the authorization data fails and treating it as an authorization value if the length is 32 bytes. But as this value is chosen by snapd and nothing in secboot enforces a size of 32 bytes, I thought it was safer to have this as 2 APIs so that snapd can be explicit about the format of the supplied data. Fixes: FR-10809
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pedronis
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Mar 4, 2026
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| _, err := params.AuthPolicy.Execute( | ||
| policyutil.NewPolicyExecuteSession(t.TPMContext, session), | ||
| policyutil.WithSessionUsageCommandConstraint(tpm2.CommandDictionaryAttackLockReset, []policyutil.NamedHandle{t.LockoutHandleContext()}), |
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can you comment on this bit of setup?
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This adds initial APIs for resetting the TPM's dictionary attack counter
to replace the direct use of go-tpm2's
TPMContext.DictionaryAttackLockResetAPI.This doesn't yet include the changes to
Connection.EnsureProvisionedwhich will create the authorization data that will be persisted by
snapd and passed to this new API - this is coming in a follow-up PR.
This is split into 2 APIs:
Connection.ResetDictionaryAttackLockwhich will be supplied with datathat will be provided by an updated
EnsureProvisionedAPI.Connection.ResetDictionaryAttackLockWithAuthValuewhich will besupplied with a plain authorization value, previously chosen by snapd
and provided to the current
EnsureProvisionedAPI.I did think about having this as 1 API, and handling the case where
decoding of the authorization data fails and treating it as an
authorization value if the length is 32 bytes. But as this value is
chosen by snapd and nothing in secboot enforces a size of 32 bytes, I
thought it was safer to have this as 2 APIs so that snapd can be
explicit about the format of the supplied data.
Fixes: FR-10809