410 lines
14 KiB
Go
410 lines
14 KiB
Go
package awsauth
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import (
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"context"
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"fmt"
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"strings"
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"sync"
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"time"
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"github.com/aws/aws-sdk-go/aws/endpoints"
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"github.com/aws/aws-sdk-go/service/ec2"
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"github.com/aws/aws-sdk-go/service/iam"
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"github.com/hashicorp/vault/sdk/framework"
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"github.com/hashicorp/vault/sdk/helper/awsutil"
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"github.com/hashicorp/vault/sdk/helper/consts"
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"github.com/hashicorp/vault/sdk/logical"
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cache "github.com/patrickmn/go-cache"
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)
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const amzHeaderPrefix = "X-Amz-"
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var defaultAllowedSTSRequestHeaders = []string{
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"X-Amz-Algorithm",
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"X-Amz-Content-Sha256",
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"X-Amz-Credential",
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"X-Amz-Date",
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"X-Amz-Security-Token",
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"X-Amz-Signature",
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"X-Amz-SignedHeaders",
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}
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func Factory(ctx context.Context, conf *logical.BackendConfig) (logical.Backend, error) {
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b, err := Backend(conf)
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if err != nil {
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return nil, err
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}
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if err := b.Setup(ctx, conf); err != nil {
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return nil, err
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}
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return b, nil
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}
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type backend struct {
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*framework.Backend
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// Lock to make changes to any of the backend's configuration endpoints.
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configMutex sync.RWMutex
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// Lock to make changes to role entries
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roleMutex sync.Mutex
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// Lock to make changes to the deny list entries
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denyListMutex sync.RWMutex
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// Guards the deny list/access list tidy functions
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tidyDenyListCASGuard *uint32
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tidyAccessListCASGuard *uint32
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// Duration after which the periodic function of the backend needs to
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// tidy the deny list and access list entries.
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tidyCooldownPeriod time.Duration
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// nextTidyTime holds the time at which the periodic func should initiate
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// the tidy operations. This is set by the periodicFunc based on the value
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// of tidyCooldownPeriod.
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nextTidyTime time.Time
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// Map to hold the EC2 client objects indexed by region and STS role.
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// This avoids the overhead of creating a client object for every login request.
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// When the credentials are modified or deleted, all the cached client objects
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// will be flushed. The empty STS role signifies the master account
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EC2ClientsMap map[string]map[string]*ec2.EC2
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// Map to hold the IAM client objects indexed by region and STS role.
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// This avoids the overhead of creating a client object for every login request.
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// When the credentials are modified or deleted, all the cached client objects
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// will be flushed. The empty STS role signifies the master account
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IAMClientsMap map[string]map[string]*iam.IAM
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// Map to associate a partition to a random region in that partition. Users of
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// this don't care what region in the partition they use, but there is some client
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// cache efficiency gain if we keep the mapping stable, hence caching a single copy.
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partitionToRegionMap map[string]*endpoints.Region
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// Map of AWS unique IDs to the full ARN corresponding to that unique ID
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// This avoids the overhead of an AWS API hit for every login request
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// using the IAM auth method when bound_iam_principal_arn contains a wildcard
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iamUserIdToArnCache *cache.Cache
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// AWS Account ID of the "default" AWS credentials
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// This cache avoids the need to call GetCallerIdentity repeatedly to learn it
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// We can't store this because, in certain pathological cases, it could change
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// out from under us, such as a standby and active Vault server in different AWS
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// accounts using their IAM instance profile to get their credentials.
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defaultAWSAccountID string
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// roleCache caches role entries to avoid locking headaches
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roleCache *cache.Cache
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resolveArnToUniqueIDFunc func(context.Context, logical.Storage, string) (string, error)
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// upgradeCancelFunc is used to cancel the context used in the upgrade
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// function
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upgradeCancelFunc context.CancelFunc
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// deprecatedTerms is used to downgrade preferred terminology (e.g. accesslist)
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// to the legacy term. This allows for consolidated aliasing of the affected
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// endpoints until the legacy terms are removed.
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deprecatedTerms *strings.Replacer
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}
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func Backend(_ *logical.BackendConfig) (*backend, error) {
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b := &backend{
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// Setting the periodic func to be run once in an hour.
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// If there is a real need, this can be made configurable.
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tidyCooldownPeriod: time.Hour,
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EC2ClientsMap: make(map[string]map[string]*ec2.EC2),
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IAMClientsMap: make(map[string]map[string]*iam.IAM),
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iamUserIdToArnCache: cache.New(7*24*time.Hour, 24*time.Hour),
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tidyDenyListCASGuard: new(uint32),
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tidyAccessListCASGuard: new(uint32),
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roleCache: cache.New(cache.NoExpiration, cache.NoExpiration),
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deprecatedTerms: strings.NewReplacer(
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"accesslist", "whitelist",
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"denylist", "blacklist",
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),
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}
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b.resolveArnToUniqueIDFunc = b.resolveArnToRealUniqueId
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b.Backend = &framework.Backend{
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PeriodicFunc: b.periodicFunc,
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AuthRenew: b.pathLoginRenew,
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Help: backendHelp,
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PathsSpecial: &logical.Paths{
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Unauthenticated: []string{
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"login",
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},
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LocalStorage: []string{
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identityAccessListStorage,
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},
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SealWrapStorage: []string{
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"config/client",
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},
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},
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Paths: []*framework.Path{
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b.pathLogin(),
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b.pathListRole(),
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b.pathListRoles(),
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b.pathRole(),
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b.pathRoleTag(),
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b.pathConfigClient(),
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b.pathConfigCertificate(),
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b.pathConfigIdentity(),
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b.pathConfigRotateRoot(),
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b.pathConfigSts(),
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b.pathListSts(),
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b.pathListCertificates(),
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// The following pairs of functions are path aliases. The first is the
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// primary endpoint, and the second is version using deprecated language,
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// for backwards compatibility. The functionality is identical between the two.
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b.pathConfigTidyRoletagDenyList(),
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b.genDeprecatedPath(b.pathConfigTidyRoletagDenyList()),
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b.pathConfigTidyIdentityAccessList(),
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b.genDeprecatedPath(b.pathConfigTidyIdentityAccessList()),
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b.pathListRoletagDenyList(),
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b.genDeprecatedPath(b.pathListRoletagDenyList()),
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b.pathRoletagDenyList(),
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b.genDeprecatedPath(b.pathRoletagDenyList()),
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b.pathTidyRoletagDenyList(),
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b.genDeprecatedPath(b.pathTidyRoletagDenyList()),
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b.pathListIdentityAccessList(),
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b.genDeprecatedPath(b.pathListIdentityAccessList()),
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b.pathIdentityAccessList(),
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b.genDeprecatedPath(b.pathIdentityAccessList()),
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b.pathTidyIdentityAccessList(),
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b.genDeprecatedPath(b.pathTidyIdentityAccessList()),
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},
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Invalidate: b.invalidate,
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InitializeFunc: b.initialize,
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BackendType: logical.TypeCredential,
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Clean: b.cleanup,
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}
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b.partitionToRegionMap = generatePartitionToRegionMap()
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return b, nil
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}
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// periodicFunc performs the tasks that the backend wishes to do periodically.
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// Currently this will be triggered once in a minute by the RollbackManager.
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//
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// The tasks being done currently by this function are to cleanup the expired
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// entries of both deny list role tags and access list identities. Tidying is done
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// not once in a minute, but once in an hour, controlled by 'tidyCooldownPeriod'.
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// Tidying of deny list and access list are by default enabled. This can be
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// changed using `config/tidy/roletags` and `config/tidy/identities` endpoints.
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func (b *backend) periodicFunc(ctx context.Context, req *logical.Request) error {
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// Run the tidy operations for the first time. Then run it when current
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// time matches the nextTidyTime.
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if b.nextTidyTime.IsZero() || !time.Now().Before(b.nextTidyTime) {
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if b.System().LocalMount() || !b.System().ReplicationState().HasState(consts.ReplicationPerformanceSecondary|consts.ReplicationPerformanceStandby) {
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// safetyBuffer defaults to 180 days for roletag deny list
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safetyBuffer := 15552000
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tidyBlacklistConfigEntry, err := b.lockedConfigTidyRoleTags(ctx, req.Storage)
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if err != nil {
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return err
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}
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skipBlacklistTidy := false
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// check if tidying of role tags was configured
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if tidyBlacklistConfigEntry != nil {
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// check if periodic tidying of role tags was disabled
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if tidyBlacklistConfigEntry.DisablePeriodicTidy {
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skipBlacklistTidy = true
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}
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// overwrite the default safetyBuffer with the configured value
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safetyBuffer = tidyBlacklistConfigEntry.SafetyBuffer
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}
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// tidy role tags if explicitly not disabled
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if !skipBlacklistTidy {
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b.tidyDenyListRoleTag(ctx, req, safetyBuffer)
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}
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}
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// We don't check for replication state for access list identities as
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// these are locally stored
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safety_buffer := 259200
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tidyWhitelistConfigEntry, err := b.lockedConfigTidyIdentities(ctx, req.Storage)
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if err != nil {
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return err
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}
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skipWhitelistTidy := false
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// check if tidying of identities was configured
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if tidyWhitelistConfigEntry != nil {
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// check if periodic tidying of identities was disabled
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if tidyWhitelistConfigEntry.DisablePeriodicTidy {
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skipWhitelistTidy = true
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}
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// overwrite the default safety_buffer with the configured value
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safety_buffer = tidyWhitelistConfigEntry.SafetyBuffer
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}
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// tidy identities if explicitly not disabled
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if !skipWhitelistTidy {
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b.tidyAccessListIdentity(ctx, req, safety_buffer)
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}
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// Update the time at which to run the tidy functions again.
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b.nextTidyTime = time.Now().Add(b.tidyCooldownPeriod)
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}
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return nil
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}
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func (b *backend) cleanup(ctx context.Context) {
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if b.upgradeCancelFunc != nil {
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b.upgradeCancelFunc()
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}
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}
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func (b *backend) invalidate(ctx context.Context, key string) {
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switch {
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case key == "config/client":
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b.configMutex.Lock()
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defer b.configMutex.Unlock()
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b.flushCachedEC2Clients()
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b.flushCachedIAMClients()
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b.defaultAWSAccountID = ""
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case strings.HasPrefix(key, "role"):
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// TODO: We could make this better
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b.roleCache.Flush()
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}
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}
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// Putting this here so we can inject a fake resolver into the backend for unit testing
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// purposes
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func (b *backend) resolveArnToRealUniqueId(ctx context.Context, s logical.Storage, arn string) (string, error) {
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entity, err := parseIamArn(arn)
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if err != nil {
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return "", err
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}
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// This odd-looking code is here because IAM is an inherently global service. IAM and STS ARNs
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// don't have regions in them, and there is only a single global endpoint for IAM; see
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// http://docs.aws.amazon.com/general/latest/gr/rande.html#iam_region
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// However, the ARNs do have a partition in them, because the GovCloud and China partitions DO
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// have their own separate endpoints, and the partition is encoded in the ARN. If Amazon's Go SDK
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// would allow us to pass a partition back to the IAM client, it would be much simpler. But it
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// doesn't appear that's possible, so in order to properly support GovCloud and China, we do a
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// circular dance of extracting the partition from the ARN, finding any arbitrary region in the
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// partition, and passing that region back back to the SDK, so that the SDK can figure out the
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// proper partition from the arbitrary region we passed in to look up the endpoint.
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// Sigh
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region := b.partitionToRegionMap[entity.Partition]
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if region == nil {
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return "", fmt.Errorf("unable to resolve partition %q to a region", entity.Partition)
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}
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iamClient, err := b.clientIAM(ctx, s, region.ID(), entity.AccountNumber)
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if err != nil {
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return "", awsutil.AppendAWSError(err)
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}
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switch entity.Type {
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case "user":
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userInfo, err := iamClient.GetUser(&iam.GetUserInput{UserName: &entity.FriendlyName})
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if err != nil {
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return "", awsutil.AppendAWSError(err)
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}
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if userInfo == nil {
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return "", fmt.Errorf("got nil result from GetUser")
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}
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return *userInfo.User.UserId, nil
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case "role":
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roleInfo, err := iamClient.GetRole(&iam.GetRoleInput{RoleName: &entity.FriendlyName})
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if err != nil {
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return "", awsutil.AppendAWSError(err)
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}
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if roleInfo == nil {
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return "", fmt.Errorf("got nil result from GetRole")
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}
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return *roleInfo.Role.RoleId, nil
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case "instance-profile":
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profileInfo, err := iamClient.GetInstanceProfile(&iam.GetInstanceProfileInput{InstanceProfileName: &entity.FriendlyName})
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if err != nil {
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return "", awsutil.AppendAWSError(err)
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}
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if profileInfo == nil {
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return "", fmt.Errorf("got nil result from GetInstanceProfile")
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}
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return *profileInfo.InstanceProfile.InstanceProfileId, nil
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default:
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return "", fmt.Errorf("unrecognized error type %#v", entity.Type)
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}
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}
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// genDeprecatedPath will return a deprecated version of a framework.Path. The will include
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// using deprecated terms in the path pattern, and marking the path as deprecated.
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func (b *backend) genDeprecatedPath(path *framework.Path) *framework.Path {
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pathDeprecated := *path
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pathDeprecated.Pattern = b.deprecatedTerms.Replace(path.Pattern)
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pathDeprecated.Deprecated = true
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return &pathDeprecated
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}
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// Adapted from https://docs.aws.amazon.com/sdk-for-go/api/aws/endpoints/
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// the "Enumerating Regions and Endpoint Metadata" section
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func generatePartitionToRegionMap() map[string]*endpoints.Region {
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partitionToRegion := make(map[string]*endpoints.Region)
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resolver := endpoints.DefaultResolver()
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partitions := resolver.(endpoints.EnumPartitions).Partitions()
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for _, p := range partitions {
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// For most partitions, it's fine to choose a single region randomly.
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// However, there are a few exceptions:
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//
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// For "aws", choose "us-east-1" because it is always enabled (and
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// enabled for STS) by default.
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//
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// For "aws-us-gov", choose "us-gov-west-1" because it is the only
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// valid region for IAM operations.
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// ref: https://github.com/aws/aws-sdk-go/blob/v1.34.25/aws/endpoints/defaults.go#L8176-L8194
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for _, r := range p.Regions() {
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if p.ID() == "aws" && r.ID() != "us-east-1" {
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continue
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}
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if p.ID() == "aws-us-gov" && r.ID() != "us-gov-west-1" {
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continue
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}
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partitionToRegion[p.ID()] = &r
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break
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}
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}
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return partitionToRegion
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}
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const backendHelp = `
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The aws auth method uses either AWS IAM credentials or AWS-signed EC2 metadata
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to authenticate clients, which are IAM principals or EC2 instances.
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Authentication is backed by a preconfigured role in the backend. The role
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represents the authorization of resources by containing Vault's policies.
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Role can be created using 'role/<role>' endpoint.
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Authentication of IAM principals, either IAM users or roles, is done using a
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specifically signed AWS API request using clients' AWS IAM credentials. IAM
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principals can then be assigned to roles within Vault. This is known as the
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"iam" auth method.
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Authentication of EC2 instances is done using either a signed PKCS#7 document
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or a detached RSA signature of an AWS EC2 instance's identity document along
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with a client-created nonce. This is known as the "ec2" auth method.
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If there is need to further restrict the capabilities of the role on the instance
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that is using the role, 'role_tag' option can be enabled on the role, and a tag
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can be generated using 'role/<role>/tag' endpoint. This tag represents the
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subset of capabilities set on the role. When the 'role_tag' option is enabled on
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the role, the login operation requires that a respective role tag is attached to
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the EC2 instance which performs the login.
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`
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