[v14][buddy] Truncate AssumeRole session name to API limits

lib/srv/app/cloud.go

@@ -182,7 +182,7 @@ func (c *cloud) getAWSSigninToken(req *AWSSigninRequest, endpoint string, option
 	options = append(options, func(creds *stscreds.AssumeRoleProvider) {
 		// Setting role session name to Teleport username will allow to
 		// associate CloudTrail events with the Teleport user.
-		creds.RoleSessionName = req.Identity.Username
+		creds.RoleSessionName = awsutils.MaybeHashRoleSessionName(req.Identity.Username)
 
 		// Setting web console session duration through AssumeRole call for AWS
 		// sessions with temporary credentials.

lib/utils/aws/aws.go

@@ -19,6 +19,8 @@ package aws
 import (
 	"bytes"
 	"context"
+	"crypto/sha1"
+	"encoding/hex"
 	"fmt"
 	"net/http"
 	"net/textproto"
@@ -66,6 +68,11 @@ const (
 	AmzJSON1_0 = "application/x-amz-json-1.0"
 	// AmzJSON1_1 is an AWS Content-Type header that indicates the media type is JSON.
 	AmzJSON1_1 = "application/x-amz-json-1.1"
+
+	// MaxRoleSessionNameLength is the maximum length of the role session name
+	// used by the AssumeRole call.
+	// https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_iam-quotas.html
+	MaxRoleSessionNameLength = 64
 )
 
 // SigV4 contains parsed content of the AWS Authorization header.
@@ -479,3 +486,30 @@ func iamResourceARN(partition, accountID, resourceType, resourceName string) str
 		Resource:  fmt.Sprintf("%s/%s", resourceType, resourceName),
 	}.String()
 }
+
+// MaybeHashRoleSessionName truncates the role session name and adds a hash
+// when the original role session name is greater than AWS character limit
+// (64).
+func MaybeHashRoleSessionName(roleSessionName string) (ret string) {
+	if len(roleSessionName) <= MaxRoleSessionNameLength {
+		return roleSessionName
+	}
+
+	const hashLen = 16
+	hash := sha1.New()
+	hash.Write([]byte(roleSessionName))
+	hex := hex.EncodeToString(hash.Sum(nil))[:hashLen]
+
+	// "1" for the delimiter.
+	keepPrefixIndex := MaxRoleSessionNameLength - len(hex) - 1
+
+	// Sanity check. This should never happen since hash length and
+	// MaxRoleSessionNameLength are both constant.
+	if keepPrefixIndex < 0 {
+		keepPrefixIndex = 0
+	}
+
+	ret = fmt.Sprintf("%s-%s", roleSessionName[:keepPrefixIndex], hex)
+	logrus.Debugf("AWS role session name %q is too long. Using a hash %q instead.", roleSessionName, ret)
+	return ret
+}

lib/utils/aws/aws_test.go

@@ -487,3 +487,33 @@ func TestResourceARN(t *testing.T) {
 		})
 	}
 }
+
+func TestMaybeHashRoleSessionName(t *testing.T) {
+	for _, tt := range []struct {
+		name     string
+		role     string
+		expected string
+	}{
+		{
+			name:     "role session name not hashed, less than 64 characters",
+			role:     "MyRole",
+			expected: "MyRole",
+		},
+		{
+			name:     "role session name not hashed, exactly 64 characters",
+			role:     "Role123456789012345678901234567890123456789012345678901234567890",
+			expected: "Role123456789012345678901234567890123456789012345678901234567890",
+		},
+		{
+			name:     "role session name hashed, longer than 64 characters",
+			role:     "remote-raimundo.oliveira@abigcompany.com-teleport.abigcompany.com",
+			expected: "[email protected]",
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			actual := MaybeHashRoleSessionName(tt.role)
+			require.Equal(t, tt.expected, actual)
+			require.LessOrEqual(t, len(actual), MaxRoleSessionNameLength)
+		})
+	}
+}

lib/utils/aws/credentials.go

@@ -66,7 +66,7 @@ func (g *credentialsGetter) Get(_ context.Context, request GetCredentialsRequest
 	logrus.Debugf("Creating STS session %q for %q.", request.SessionName, request.RoleARN)
 	return stscreds.NewCredentials(request.Provider, request.RoleARN,
 		func(cred *stscreds.AssumeRoleProvider) {
-			cred.RoleSessionName = request.SessionName
+			cred.RoleSessionName = MaybeHashRoleSessionName(request.SessionName)
 			cred.Expiry.SetExpiration(request.Expiry, 0)
 
 			if request.ExternalID != "" {