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Diffstat (limited to 'vendor/github.com/aws/aws-sdk-go/aws/credentials/stscreds/assume_role_provider.go')
| -rw-r--r-- | vendor/github.com/aws/aws-sdk-go/aws/credentials/stscreds/assume_role_provider.go | 298 |
1 files changed, 298 insertions, 0 deletions
diff --git a/vendor/github.com/aws/aws-sdk-go/aws/credentials/stscreds/assume_role_provider.go b/vendor/github.com/aws/aws-sdk-go/aws/credentials/stscreds/assume_role_provider.go new file mode 100644 index 00000000..4108e433 --- /dev/null +++ b/vendor/github.com/aws/aws-sdk-go/aws/credentials/stscreds/assume_role_provider.go @@ -0,0 +1,298 @@ +/* +Package stscreds are credential Providers to retrieve STS AWS credentials. + +STS provides multiple ways to retrieve credentials which can be used when making +future AWS service API operation calls. + +The SDK will ensure that per instance of credentials.Credentials all requests +to refresh the credentials will be synchronized. But, the SDK is unable to +ensure synchronous usage of the AssumeRoleProvider if the value is shared +between multiple Credentials, Sessions or service clients. + +Assume Role + +To assume an IAM role using STS with the SDK you can create a new Credentials +with the SDKs's stscreds package. + + // Initial credentials loaded from SDK's default credential chain. Such as + // the environment, shared credentials (~/.aws/credentials), or EC2 Instance + // Role. These credentials will be used to to make the STS Assume Role API. + sess := session.Must(session.NewSession()) + + // Create the credentials from AssumeRoleProvider to assume the role + // referenced by the "myRoleARN" ARN. + creds := stscreds.NewCredentials(sess, "myRoleArn") + + // Create service client value configured for credentials + // from assumed role. + svc := s3.New(sess, &aws.Config{Credentials: creds}) + +Assume Role with static MFA Token + +To assume an IAM role with a MFA token you can either specify a MFA token code +directly or provide a function to prompt the user each time the credentials +need to refresh the role's credentials. Specifying the TokenCode should be used +for short lived operations that will not need to be refreshed, and when you do +not want to have direct control over the user provides their MFA token. + +With TokenCode the AssumeRoleProvider will be not be able to refresh the role's +credentials. + + // Create the credentials from AssumeRoleProvider to assume the role + // referenced by the "myRoleARN" ARN using the MFA token code provided. + creds := stscreds.NewCredentials(sess, "myRoleArn", func(p *stscreds.AssumeRoleProvider) { + p.SerialNumber = aws.String("myTokenSerialNumber") + p.TokenCode = aws.String("00000000") + }) + + // Create service client value configured for credentials + // from assumed role. + svc := s3.New(sess, &aws.Config{Credentials: creds}) + +Assume Role with MFA Token Provider + +To assume an IAM role with MFA for longer running tasks where the credentials +may need to be refreshed setting the TokenProvider field of AssumeRoleProvider +will allow the credential provider to prompt for new MFA token code when the +role's credentials need to be refreshed. + +The StdinTokenProvider function is available to prompt on stdin to retrieve +the MFA token code from the user. You can also implement custom prompts by +satisfing the TokenProvider function signature. + +Using StdinTokenProvider with multiple AssumeRoleProviders, or Credentials will +have undesirable results as the StdinTokenProvider will not be synchronized. A +single Credentials with an AssumeRoleProvider can be shared safely. + + // Create the credentials from AssumeRoleProvider to assume the role + // referenced by the "myRoleARN" ARN. Prompting for MFA token from stdin. + creds := stscreds.NewCredentials(sess, "myRoleArn", func(p *stscreds.AssumeRoleProvider) { + p.SerialNumber = aws.String("myTokenSerialNumber") + p.TokenProvider = stscreds.StdinTokenProvider + }) + + // Create service client value configured for credentials + // from assumed role. + svc := s3.New(sess, &aws.Config{Credentials: creds}) + +*/ +package stscreds + +import ( + "fmt" + "time" + + "github.com/aws/aws-sdk-go/aws" + "github.com/aws/aws-sdk-go/aws/awserr" + "github.com/aws/aws-sdk-go/aws/client" + "github.com/aws/aws-sdk-go/aws/credentials" + "github.com/aws/aws-sdk-go/service/sts" +) + +// StdinTokenProvider will prompt on stdout and read from stdin for a string value. +// An error is returned if reading from stdin fails. +// +// Use this function go read MFA tokens from stdin. The function makes no attempt +// to make atomic prompts from stdin across multiple gorouties. +// +// Using StdinTokenProvider with multiple AssumeRoleProviders, or Credentials will +// have undesirable results as the StdinTokenProvider will not be synchronized. A +// single Credentials with an AssumeRoleProvider can be shared safely +// +// Will wait forever until something is provided on the stdin. +func StdinTokenProvider() (string, error) { + var v string + fmt.Printf("Assume Role MFA token code: ") + _, err := fmt.Scanln(&v) + + return v, err +} + +// ProviderName provides a name of AssumeRole provider +const ProviderName = "AssumeRoleProvider" + +// AssumeRoler represents the minimal subset of the STS client API used by this provider. +type AssumeRoler interface { + AssumeRole(input *sts.AssumeRoleInput) (*sts.AssumeRoleOutput, error) +} + +// DefaultDuration is the default amount of time in minutes that the credentials +// will be valid for. +var DefaultDuration = time.Duration(15) * time.Minute + +// AssumeRoleProvider retrieves temporary credentials from the STS service, and +// keeps track of their expiration time. +// +// This credential provider will be used by the SDKs default credential change +// when shared configuration is enabled, and the shared config or shared credentials +// file configure assume role. See Session docs for how to do this. +// +// AssumeRoleProvider does not provide any synchronization and it is not safe +// to share this value across multiple Credentials, Sessions, or service clients +// without also sharing the same Credentials instance. +type AssumeRoleProvider struct { + credentials.Expiry + + // STS client to make assume role request with. + Client AssumeRoler + + // Role to be assumed. + RoleARN string + + // Session name, if you wish to reuse the credentials elsewhere. + RoleSessionName string + + // Expiry duration of the STS credentials. Defaults to 15 minutes if not set. + Duration time.Duration + + // Optional ExternalID to pass along, defaults to nil if not set. + ExternalID *string + + // The policy plain text must be 2048 bytes or shorter. However, an internal + // conversion compresses it into a packed binary format with a separate limit. + // The PackedPolicySize response element indicates by percentage how close to + // the upper size limit the policy is, with 100% equaling the maximum allowed + // size. + Policy *string + + // The identification number of the MFA device that is associated with the user + // who is making the AssumeRole call. Specify this value if the trust policy + // of the role being assumed includes a condition that requires MFA authentication. + // The value is either the serial number for a hardware device (such as GAHT12345678) + // or an Amazon Resource Name (ARN) for a virtual device (such as arn:aws:iam::123456789012:mfa/user). + SerialNumber *string + + // The value provided by the MFA device, if the trust policy of the role being + // assumed requires MFA (that is, if the policy includes a condition that tests + // for MFA). If the role being assumed requires MFA and if the TokenCode value + // is missing or expired, the AssumeRole call returns an "access denied" error. + // + // If SerialNumber is set and neither TokenCode nor TokenProvider are also + // set an error will be returned. + TokenCode *string + + // Async method of providing MFA token code for assuming an IAM role with MFA. + // The value returned by the function will be used as the TokenCode in the Retrieve + // call. See StdinTokenProvider for a provider that prompts and reads from stdin. + // + // This token provider will be called when ever the assumed role's + // credentials need to be refreshed when SerialNumber is also set and + // TokenCode is not set. + // + // If both TokenCode and TokenProvider is set, TokenProvider will be used and + // TokenCode is ignored. + TokenProvider func() (string, error) + + // ExpiryWindow will allow the credentials to trigger refreshing prior to + // the credentials actually expiring. This is beneficial so race conditions + // with expiring credentials do not cause request to fail unexpectedly + // due to ExpiredTokenException exceptions. + // + // So a ExpiryWindow of 10s would cause calls to IsExpired() to return true + // 10 seconds before the credentials are actually expired. + // + // If ExpiryWindow is 0 or less it will be ignored. + ExpiryWindow time.Duration +} + +// NewCredentials returns a pointer to a new Credentials object wrapping the +// AssumeRoleProvider. The credentials will expire every 15 minutes and the +// role will be named after a nanosecond timestamp of this operation. +// +// Takes a Config provider to create the STS client. The ConfigProvider is +// satisfied by the session.Session type. +// +// It is safe to share the returned Credentials with multiple Sessions and +// service clients. All access to the credentials and refreshing them +// will be synchronized. +func NewCredentials(c client.ConfigProvider, roleARN string, options ...func(*AssumeRoleProvider)) *credentials.Credentials { + p := &AssumeRoleProvider{ + Client: sts.New(c), + RoleARN: roleARN, + Duration: DefaultDuration, + } + + for _, option := range options { + option(p) + } + + return credentials.NewCredentials(p) +} + +// NewCredentialsWithClient returns a pointer to a new Credentials object wrapping the +// AssumeRoleProvider. The credentials will expire every 15 minutes and the +// role will be named after a nanosecond timestamp of this operation. +// +// Takes an AssumeRoler which can be satisfied by the STS client. +// +// It is safe to share the returned Credentials with multiple Sessions and +// service clients. All access to the credentials and refreshing them +// will be synchronized. +func NewCredentialsWithClient(svc AssumeRoler, roleARN string, options ...func(*AssumeRoleProvider)) *credentials.Credentials { + p := &AssumeRoleProvider{ + Client: svc, + RoleARN: roleARN, + Duration: DefaultDuration, + } + + for _, option := range options { + option(p) + } + + return credentials.NewCredentials(p) +} + +// Retrieve generates a new set of temporary credentials using STS. +func (p *AssumeRoleProvider) Retrieve() (credentials.Value, error) { + + // Apply defaults where parameters are not set. + if p.RoleSessionName == "" { + // Try to work out a role name that will hopefully end up unique. + p.RoleSessionName = fmt.Sprintf("%d", time.Now().UTC().UnixNano()) + } + if p.Duration == 0 { + // Expire as often as AWS permits. + p.Duration = DefaultDuration + } + input := &sts.AssumeRoleInput{ + DurationSeconds: aws.Int64(int64(p.Duration / time.Second)), + RoleArn: aws.String(p.RoleARN), + RoleSessionName: aws.String(p.RoleSessionName), + ExternalId: p.ExternalID, + } + if p.Policy != nil { + input.Policy = p.Policy + } + if p.SerialNumber != nil { + if p.TokenCode != nil { + input.SerialNumber = p.SerialNumber + input.TokenCode = p.TokenCode + } else if p.TokenProvider != nil { + input.SerialNumber = p.SerialNumber + code, err := p.TokenProvider() + if err != nil { + return credentials.Value{ProviderName: ProviderName}, err + } + input.TokenCode = aws.String(code) + } else { + return credentials.Value{ProviderName: ProviderName}, + awserr.New("AssumeRoleTokenNotAvailable", + "assume role with MFA enabled, but neither TokenCode nor TokenProvider are set", nil) + } + } + + roleOutput, err := p.Client.AssumeRole(input) + if err != nil { + return credentials.Value{ProviderName: ProviderName}, err + } + + // We will proactively generate new credentials before they expire. + p.SetExpiration(*roleOutput.Credentials.Expiration, p.ExpiryWindow) + + return credentials.Value{ + AccessKeyID: *roleOutput.Credentials.AccessKeyId, + SecretAccessKey: *roleOutput.Credentials.SecretAccessKey, + SessionToken: *roleOutput.Credentials.SessionToken, + ProviderName: ProviderName, + }, nil +} |