Merge pull request #63 from Sea-Haven-Industries/fix/deploy-substrate-deny-self-mutation

fix(iam): port DenySelfMutation into the prod/dev deploy substrate

lib/deploy-substrate/deploy-substrate.template.yaml

@@ -30,18 +30,21 @@ Description: >-
 #     first deploy failed with ServiceLimitExceeded (2026-07-27). Effective
 #     permissions are unchanged — verified by comparing the full 27-statement
 #     set before and after the move (identical), since identity policies are
-#     unioned and an explicit Deny still wins. NOTE for the mgmt remediation:
-#     mgmt needs this same restructure before its Deny statements can be added,
-#   - SECURITY FIX, deliberate divergence: iam:DeleteRolePermissionsBoundary
+#     unioned and an explicit Deny still wins. mgmt received this same
+#     restructure in Phase B (.github PR #98), so this is no longer a
+#     divergence,
+#   - SECURITY FIX (now in BOTH copies): iam:DeleteRolePermissionsBoundary
 #     removed from Sid IAMPutPermissionsBoundary and explicit Deny statements
-#     (DenyBoundaryTampering / DenyBoundaryPolicyEdit) added. The mgmt copy
-#     still carries the hole — verified live 2026-07-27 via
-#     simulate-principal-policy on the deployed mgmt role
-#     (iam:DeleteRolePermissionsBoundary = ALLOWED). New accounts must not be
-#     born with it. Remediating mgmt means changing a role that is actively
-#     executing production deploys, so it is tracked as a separate change
-#     with its own review gates rather than folded in here. Reconcile the two
-#     copies when that lands.
+#     (DenyBoundaryTampering / DenyBoundaryPolicyEdit / DenySelfMutation)
+#     added. The mgmt copy was remediated 2026-07-27 (.github PRs #95 Phase A
+#     + #98 Phase B); DenySelfMutation and the widened policy/seahaven-*
+#     DenyBoundaryPolicyEdit scope were then ported back here, so the two
+#     copies' statement sets are reconciled as of that date — every IAM
+#     statement in LambdaExecutionBoundary, SamCfnIamManagementPolicy and
+#     SamCfnExecutionRole is byte-identical across the two files; the only
+#     remaining delta is the DependsOn line above, which is ordering, not
+#     permission. If a substrate statement changes again, change BOTH files
+#     in the same piece of work.
 #
 # This template is deployed via lib/deploy-substrate-stack.ts
 # (cloudformation-include) as stack seahaven-deploy-substrate, once per
@@ -527,6 +530,12 @@ Resources:
                   - logs:DescribeDestinations
                   - logs:AssociateKmsKey
                   - logs:DisassociateKmsKey
+                  # Ported from the mgmt copy (Phase A): afterhours-shift-manager
+                  # creates an AWS::Logs::MetricFilter through this role, so a
+                  # SAM stack migrating here fails mid-deploy without these.
+                  - logs:PutMetricFilter
+                  - logs:DeleteMetricFilter
+                  - logs:DescribeMetricFilters
                 Resource: "*"
 
         # ── EventBridge / CloudWatch Events (scheduled Lambdas) ───────────
@@ -880,6 +889,12 @@ Resources:
               - !Sub "arn:aws:iam::${AWS::AccountId}:role/*"
               - !Sub "arn:aws:iam::${AWS::AccountId}:user/*"
 
+          # Scoped to the whole seahaven-* policy family, not just the boundary:
+          # this policy carries the Deny statements, so it is now a
+          # higher-value target than the boundary it protects. Safe to scope
+          # broadly — the role holds no iam:CreatePolicy anywhere and no SAM
+          # stack manages a managed policy through it (both verified
+          # 2026-07-27), so nothing legitimate writes policy versions here.
           - Sid: DenyBoundaryPolicyEdit
             Effect: Deny
             Action:
@@ -888,7 +903,50 @@ Resources:
               - iam:DeletePolicyVersion
               - iam:DeletePolicy
             Resource:
-              - !Sub "arn:aws:iam::${AWS::AccountId}:policy/seahaven-lambda-execution-boundary"
+              - !Sub "arn:aws:iam::${AWS::AccountId}:policy/seahaven-*"
+
+          # Self-protection. Without this the whole control is one API call
+          # from being undone: IAMRoleReadAndDelete below grants
+          # iam:DetachRolePolicy on Resource "*" with no condition, so this
+          # role could detach the very policy carrying these Denies from
+          # itself and reinstate the escalation. Verified live 2026-07-27:
+          # simulate-principal-policy returned "allowed" for DetachRolePolicy,
+          # DeleteRolePolicy and DeleteRole against this role's own ARN and
+          # against githubdeploy-* roles.
+          #
+          # Also closes a denial-of-service and a self-elevation precondition:
+          # iam:PutRolePermissionsBoundary is condition-pinned to the Lambda
+          # boundary ARN but NOT scoped by target, so this role could apply
+          # that runtime boundary to itself or to a githubdeploy-* role —
+          # bricking the pipelines, unrecoverable without an admin because
+          # removing a boundary is denied above, and making the otherwise-inert
+          # AttachRolePolicy/PutRolePolicy self-elevation conditions start
+          # matching.
+          #
+          # Costs nothing operationally: this role is only ever passed to
+          # CloudFormation for SAM application stacks. The substrate's own
+          # roles are managed by THIS stack (deployed through the CDK
+          # bootstrap execution role), and per-repo githubdeploy-* roles are
+          # provisioned at onboarding time outside any stack this role
+          # executes — so CloudFormation never exercises these actions
+          # against them as this role. SAM-generated roles are named
+          # <stack>-<Function>Role-<hash> and are unaffected.
+          - Sid: DenySelfMutation
+            Effect: Deny
+            Action:
+              - iam:AttachRolePolicy
+              - iam:DeleteRole
+              - iam:DeleteRolePolicy
+              - iam:DeleteRolePermissionsBoundary
+              - iam:DetachRolePolicy
+              - iam:PutRolePolicy
+              - iam:PutRolePermissionsBoundary
+              - iam:UpdateAssumeRolePolicy
+              - iam:UpdateRole
+              - iam:UpdateRoleDescription
+            Resource:
+              - !Sub "arn:aws:iam::${AWS::AccountId}:role/github-cfn-execution-role"
+              - !Sub "arn:aws:iam::${AWS::AccountId}:role/githubdeploy-*"
 
           # Read / tag / delete role and policy — no boundary condition needed
           - Sid: IAMRoleReadAndDelete