mirror of https://github.com/hashicorp/consul
222 lines
11 KiB
Go
222 lines
11 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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package ca
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import (
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"crypto/x509"
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"errors"
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)
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//go:generate mockery --name Provider --inpackage
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// ErrRateLimited is a sentinel error value Providers may return from any method
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// to indicate that the operation can't complete due to a temporary rate limit.
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// In the case of signing new certificates, Consul clients will respect this and
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// intelligently backoff to optimize rotation rollout time while reducing load
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// on servers and CA provider.
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var ErrRateLimited = errors.New("operation rate limited by CA provider")
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// PrimaryUsesIntermediate is an optional interface that CA providers may implement
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// to indicate that they use an intermediate cert in the primary datacenter as
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// well as the secondary. This is used when determining whether to run the
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// intermediate renewal routine in the primary.
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type PrimaryUsesIntermediate interface {
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// GenerateLeafSigningCert returns a new intermediate signing cert and sets it to
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// the active intermediate. If multiple intermediates are needed to complete
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// the chain from the signing certificate back to the active root, they should
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// all by bundled here.
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GenerateLeafSigningCert() (string, error)
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}
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// ProviderConfig encapsulates all the data Consul passes to `Configure` on a
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// new provider instance. The provider must treat this as read-only and make
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// copies of any map or slice if it might modify them internally.
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type ProviderConfig struct {
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// ClusterID is the current Consul cluster ID.
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ClusterID string
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// Datacenter is the current Consul datacenter.
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Datacenter string
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// IsPrimary is true when the CA instance is in the primary DC typically it
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// may choose to act as a root in this case while secondaries are typically
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// intermediate CAs. In some case the primary DC in Consul is an intermediate
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// signed by some external CA along with that CA's public cert so the old name
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// of `IsRoot` was misleading.
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IsPrimary bool
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// RawConfig is the user configuration for the provider and is
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// provider-specific to be interpreted as the provider wishes.
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RawConfig map[string]interface{}
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// State contains the State the same provider last persisted. It is provided
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// after a restart or reconfiguration, or on a leader election on a new server
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// to maintain operation. It MUST NOT be used for secret storage since it is
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// visible in the API to operators. It's intended use is to store small bits
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// of state like UUIDs of external resources that the provider has created and
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// needs to continue to manage.
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State map[string]string
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}
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// Provider is the interface for Consul to interact with
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// an external CA that provides leaf certificate signing for
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// given SpiffeIDServices.
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type Provider interface {
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// Configure initializes the provider based on the given cluster ID, root
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// status and configuration values. rawConfig contains the user-provided
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// Config. State contains a the State the same provider last persisted on a
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// restart or reconfiguration. The provider must not modify `rawConfig` or
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// `state` maps directly as it may be being read from other goroutines.
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Configure(cfg ProviderConfig) error
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// State returns the current provider state. If the provider doesn't need to
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// store anything other than what the user configured this can return nil. It
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// is called after any config change before the new active config is stored in
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// the state store and the most recent value returned by the provider is given
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// in subsequent `Configure` calls provided that the current provider is the
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// same type as the new provider instance being configured. This provides a
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// simple way for providers to persist information like UUIDs of resources
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// they manage. This state is visible to anyone with operator:read via the API
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// so it's not intended for storing secrets like root private keys. Only
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// strings are permitted since this has to pass through msgpack and so
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// interface values will end up mangled in many cases which is ugly for all
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// provider code to have to remember to reason about.
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//
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// Note that the map returned will be accessed (read-only) in other goroutines
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// - for example passed to Configure in the Connect CA Config RPC endpoint -
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// so it must not just be a pointer to a map that may internally be modified.
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// If the Provider only writes to it during Configure it's safe to return
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// as-is, but otherwise it's assumed the map returned is a copy of the state
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// in the Provider struct so it won't change after being returned.
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State() (map[string]string, error)
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// ActiveLeafSigningCert returns the current signing cert used by this provider
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// for generating SPIFFE leaf certs. Note that this must not change except
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// when Consul requests the change via GenerateLeafSigningCert. Changing the
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// signing cert will break Consul's assumptions about which validation paths
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// are active.
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ActiveLeafSigningCert() (string, error)
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// Sign signs a leaf certificate used by Connect proxies from a CSR. The PEM
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// returned should include only the leaf certificate as all Intermediates
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// needed to validate it will be added by Consul based on the active
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// intermediate and any cross-signed intermediates managed by Consul. Note that
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// providers should return ErrRateLimited if they are unable to complete the
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// operation due to upstream rate limiting so that clients can intelligently
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// backoff.
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Sign(*x509.CertificateRequest) (string, error)
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// Cleanup performs any necessary cleanup that should happen when the provider
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// is shut down permanently, such as removing a temporary PKI backend in Vault
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// created for an intermediate CA. Whether the CA provider type is changing
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// and the other providers raw configuration is passed along so that the provider
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// instance can determine which cleanup steps to perform. For example, when the
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// Vault provider is in use and there is no type change occuring, the Vault
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// provider should check if the intermediate PKI path is changing. If it is not
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// changing then the provider should not remove that path from Vault.
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Cleanup(providerTypeChange bool, otherConfig map[string]interface{}) error
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// TODO: when CAManager has separate types for primary/secondary invert this
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// relationship so that PrimaryProvider/SecondaryProvider embed Provider
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PrimaryProvider
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SecondaryProvider
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}
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type PrimaryProvider interface {
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// GenerateCAChain is called:
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// * to initialize the CA system when a server is elected as a raft leader
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// * when the CA configuration is updated in a way that might require
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// generating a new root certificate.
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//
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// In both cases GenerateCAChain is always called on a newly created provider
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// after calling Provider.Configure, and before any other calls to the
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// provider.
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//
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// Depending on the provider and its configuration, GenerateCAChain may return
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// a single root certificate or a chain of certs.
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// The first certificate must be the primary CA used to sign intermediates for
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// secondary datacenters, and the last certificate must be the trusted CA.
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// The provider should return an existing CA chain if one exists or generate a
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// new one and return it.
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GenerateCAChain() (string, error)
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// SignIntermediate will validate the CSR to ensure the trust domain in the
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// URI SAN matches the local one and that basic constraints for a CA
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// certificate are met. It should return a signed CA certificate with a path
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// length constraint of 0 to ensure that the certificate cannot be used to
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// generate further CA certs. Note that providers should return ErrRateLimited
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// if they are unable to complete the operation due to upstream rate limiting
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// so that clients can intelligently backoff.
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SignIntermediate(*x509.CertificateRequest) (string, error)
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// CrossSignCA must accept a CA certificate from another CA provider and cross
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// sign it exactly as it is such that it forms a chain back the the
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// CAProvider's current root. Specifically, the Distinguished Name, Subject
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// Alternative Name, SubjectKeyID and other relevant extensions must be kept.
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// The resulting certificate must have a distinct Serial Number and the
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// AuthorityKeyID set to the CAProvider's current signing key as well as the
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// Issuer related fields changed as necessary. The resulting certificate is
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// returned as a PEM formatted string.
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//
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// If the CA provider does not support this operation, it may return an error
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// provided `SupportsCrossSigning` also returns false. Note that
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// providers should return ErrRateLimited if they are unable to complete the
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// operation due to upstream rate limiting so that clients can intelligently
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// backoff.
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CrossSignCA(*x509.Certificate) (string, error)
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// SupportsCrossSigning should indicate whether the CA provider supports
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// cross-signing an external root to provide a seamless rotation. If the CA
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// does not support this, the user will have to force an upgrade when that CA
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// provider is the current CA as the upgrade may cause interruptions to
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// connectivity during the rollout.
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SupportsCrossSigning() (bool, error)
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}
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type SecondaryProvider interface {
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// GenerateIntermediateCSR should return a CSR for an intermediate CA
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// certificate. The intermediate CA will be signed by the primary CA and
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// should be used by the provider to sign leaf certificates in the local
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// datacenter.
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//
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// After the certificate is signed, SecondaryProvider.SetIntermediate will
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// be called to store the intermediate CA.
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//
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// The second return value is an opaque string meant to be passed back to
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// the subsequent call to SetIntermediate.
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GenerateIntermediateCSR() (string, string, error)
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// SetIntermediate is called to store a newly signed leaf signing certificate and
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// the chain of certificates back to the root CA certificate.
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//
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// The provider should save the certificates and use them to
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// Provider.Sign leaf certificates.
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SetIntermediate(intermediatePEM, rootPEM, opaque string) error
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}
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// CAChainResult is the result returned by PrimaryProvider.GenerateCAChain.
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type CAChainResult struct {
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// PEM encoded bundle of CA certificates. The first certificate must be the
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// primary CA used to sign intermediates for secondary datacenters, and the
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// last certificate must be the trusted CA.
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//
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// If there is only a single certificate in the bundle then it will be used
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// as both the primary CA and the trusted CA.
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PEM string
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// IntermediatePEM is an encoded bundle of CA certificates used only by
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// providers that use an intermediate CA to sign leaf certificates (e.g.
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// Vault). Its issuer should form a chain leading to the trusted CA in PEM.
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IntermediatePEM string
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}
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// NeedsStop is an optional interface that allows a CA to define a function
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// to be called when the CA instance is no longer in use. This is different
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// from Cleanup(), as only the local provider instance is being shut down
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// such as in the case of a leader change.
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type NeedsStop interface {
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Stop()
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}
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