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Add service-context login policy enforcement

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Services send service_name and tags in POST /v1/auth/login.
MCIAS evaluates auth:login policy with these as the resource
context after credentials are verified, enabling rules like:
  deny guest/viewer human accounts from env:restricted services
  deny guest accounts from specific named services

- loginRequest: add ServiceName and Tags fields
- handleLogin: evaluate policy after credential+TOTP check;
  policy deny returns 403 (not 401) to distinguish access
  restriction from bad credentials
- Go client: Options.ServiceName/Tags stored on Client,
  sent automatically in every Login() call
- Python client: service_name/tags on __init__, sent in login()
- Rust client: ClientOptions.service_name/tags, LoginRequest
  fields, Client stores and sends them in login()
- openapi.yaml: document service_name/tags request fields
  and 403 response for policy-denied logins
- engineering-standards.md: document service_name/tags in
  [mcias] config section with policy examples

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Kyle Isom
2026-03-16 21:09:38 -07:00
parent b0afe3b993
commit 39d9ffb79a
5 changed files with 136 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
clients/go/client.go
View File

@@ -185,6 +185,16 @@ type Options struct {
CACertPath string
// Token is an optional pre-existing bearer token.
Token string
// ServiceName is the name of this service as registered in MCIAS. It is
// sent with every Login call so MCIAS can evaluate service-context policy
// rules (e.g. deny guest users from logging into this service).
// Populate from [mcias] service_name in the service's config file.
ServiceName string
// Tags are the service-level tags sent with every Login call. MCIAS
// evaluates auth:login policy against these tags, enabling rules such as
// "deny guest accounts from services tagged env:restricted".
// Populate from [mcias] tags in the service's config file.
Tags []string
}
// Client is a thread-safe MCIAS REST API client.
@@ -193,6 +203,8 @@ type Options struct {
type Client struct {
baseURL string
http *http.Client
serviceName string
tags []string
mu sync.RWMutex
token string
}
@@ -227,6 +239,8 @@ func New(serverURL string, opts Options) (*Client, error) {
baseURL: serverURL,
http: &http.Client{Transport: transport},
token: opts.Token,
serviceName: opts.ServiceName,
tags: opts.Tags,
}
return c, nil
}
@@ -343,16 +357,28 @@ func (c *Client) GetPublicKey() (*PublicKey, error) {
// Login authenticates with username and password. On success the token is
// stored in the Client and returned along with the expiry timestamp.
// totpCode may be empty for accounts without TOTP.
//
// The client's ServiceName and Tags (from Options) are included in the
// request so MCIAS can evaluate service-context policy rules.
func (c *Client) Login(username, password, totpCode string) (token, expiresAt string, err error) {
req := map[string]string{"username": username, "password": password}
body := map[string]interface{}{
"username": username,
"password": password,
}
if totpCode != "" {
req["totp_code"] = totpCode
body["totp_code"] = totpCode
}
if c.serviceName != "" {
body["service_name"] = c.serviceName
}
if len(c.tags) > 0 {
body["tags"] = c.tags
}
var resp struct {
Token string `json:"token"`
ExpiresAt string `json:"expires_at"`
}
if err := c.do(http.MethodPost, "/v1/auth/login", req, &resp); err != nil {
if err := c.do(http.MethodPost, "/v1/auth/login", body, &resp); err != nil {
return "", "", err
}
c.setToken(resp.Token)

11
clients/python/mcias_client/_client.py
View File

@@ -20,9 +20,13 @@ class Client:
ca_cert_path: str | None = None,
token: str | None = None,
timeout: float = 30.0,
service_name: str | None = None,
tags: list[str] | None = None,
) -> None:
self._base_url = server_url.rstrip("/")
self.token = token
self._service_name = service_name
self._tags = tags or []
ssl_context: ssl.SSLContext | bool
if ca_cert_path is not None:
ssl_context = ssl.create_default_context(cafile=ca_cert_path)
@@ -115,6 +119,9 @@ class Client:
) -> tuple[str, str]:
"""POST /v1/auth/login — authenticate and obtain a JWT.
Returns (token, expires_at). Stores the token on self.token.
The client's service_name and tags are included so MCIAS can evaluate
service-context policy rules (e.g. deny guests from restricted services).
"""
payload: dict[str, Any] = {
"username": username,
@@ -122,6 +129,10 @@ class Client:
}
if totp_code is not None:
payload["totp_code"] = totp_code
if self._service_name is not None:
payload["service_name"] = self._service_name
if self._tags:
payload["tags"] = self._tags
data = self._request("POST", "/v1/auth/login", json=payload)
assert data is not None
token = str(data["token"])

20
clients/rust/src/lib.rs
View File

@@ -227,6 +227,10 @@ struct LoginRequest<'a> {
password: &'a str,
#[serde(skip_serializing_if = "Option::is_none")]
totp_code: Option<&'a str>,
#[serde(skip_serializing_if = "Option::is_none")]
service_name: Option<&'a str>,
#[serde(skip_serializing_if = "Vec::is_empty")]
tags: Vec<String>,
}
#[derive(Deserialize)]
@@ -268,6 +272,16 @@ pub struct ClientOptions {
/// Optional pre-existing bearer token.
pub token: Option<String>,
/// This service's name as registered in MCIAS. Sent with every login
/// request so MCIAS can evaluate service-context policy rules.
/// Populate from `[mcias] service_name` in the service config.
pub service_name: Option<String>,
/// Service-level tags sent with every login request. MCIAS evaluates
/// `auth:login` policy against these tags.
/// Populate from `[mcias] tags` in the service config.
pub tags: Vec<String>,
}
// ---- Client ----
@@ -280,6 +294,8 @@ pub struct ClientOptions {
pub struct Client {
base_url: String,
http: reqwest::Client,
service_name: Option<String>,
tags: Vec<String>,
/// Bearer token storage. `Arc<RwLock<...>>` so clones share the token.
/// Security: the token is never logged or included in error messages.
token: Arc<RwLock<Option<String>>>,
@@ -306,6 +322,8 @@ impl Client {
Ok(Self {
base_url: base_url.trim_end_matches('/').to_owned(),
http,
service_name: opts.service_name,
tags: opts.tags,
token: Arc::new(RwLock::new(opts.token)),
})
}
@@ -336,6 +354,8 @@ impl Client {
username,
password,
totp_code,
service_name: self.service_name.as_deref(),
tags: self.tags.clone(),
};
let resp: TokenResponse = self.post("/v1/auth/login", &body).await?;
*self.token.write().await = Some(resp.token.clone());

39
internal/server/server.go
View File

@@ -436,6 +436,12 @@ type loginRequest struct {
Username string `json:"username"`
Password string `json:"password"`
TOTPCode string `json:"totp_code,omitempty"`
// ServiceName and Tags identify the calling service. MCIAS evaluates the
// auth:login policy with these as the resource context, enabling operators
// to restrict which roles/account-types may log into specific services.
// Clients populate these from their [mcias] config section.
ServiceName string `json:"service_name,omitempty"`
Tags []string `json:"tags,omitempty"`
}
// loginResponse is the response body for a successful login.
@@ -546,13 +552,42 @@ func (s *Server) handleLogin(w http.ResponseWriter, r *http.Request) {
// Login succeeded: clear any outstanding failure counter.
_ = s.db.ClearLoginFailures(acct.ID)
// Determine expiry.
expiry := s.cfg.DefaultExpiry()
// Load roles for expiry decision and policy check.
roles, err := s.db.GetRoles(acct.ID)
if err != nil {
middleware.WriteError(w, http.StatusInternalServerError, "internal error", "internal_error")
return
}
// Policy check: evaluate auth:login with the calling service's context.
// Operator rules can deny login based on role, account type, service name,
// or tags. The built-in default Allow for auth:login is overridden by any
// matching Deny rule (deny-wins semantics).
//
// Security: policy is checked after credential verification so that a
// policy-denied login returns 403 (not 401), distinguishing a service
// access restriction from a wrong password without leaking user existence.
{
input := policy.PolicyInput{
Subject: acct.UUID,
AccountType: string(acct.AccountType),
Roles: roles,
Action: policy.ActionLogin,
Resource: policy.Resource{
ServiceName: req.ServiceName,
Tags: req.Tags,
},
}
if effect, _ := s.polEng.Evaluate(input); effect == policy.Deny {
s.writeAudit(r, model.EventLoginFail, &acct.ID, nil,
audit.JSON("reason", "policy_deny", "service_name", req.ServiceName))
middleware.WriteError(w, http.StatusForbidden, "access denied by policy", "policy_denied")
return
}
}
// Determine expiry.
expiry := s.cfg.DefaultExpiry()
for _, r := range roles {
if r == "admin" {
expiry = s.cfg.AdminExpiry()

32
openapi.yaml
View File

@@ -567,6 +567,12 @@ paths:
If the account has TOTP enrolled, `totp_code` is required.
Omitting it returns HTTP 401 with code `totp_required`.
`service_name` and `tags` identify the calling service. MCIAS
evaluates `auth:login` policy against these values after credentials
are verified. A policy-denied login returns HTTP 403 (not 401) so
callers can distinguish a service access restriction from bad credentials.
Clients should populate these from their `[mcias]` config section.
operationId: login
tags: [Public]
requestBody:
@@ -587,6 +593,21 @@ paths:
type: string
description: Current 6-digit TOTP code. Required if TOTP is enrolled.
example: "123456"
service_name:
type: string
description: >
Name of the calling service. Used by MCIAS to evaluate
auth:login policy rules that target specific services.
example: metatron
tags:
type: array
items:
type: string
description: >
Tags describing the calling service (e.g. "env:restricted").
MCIAS evaluates auth:login policy rules with required_tags
against this list.
example: ["env:restricted"]
responses:
"200":
description: Login successful. Returns JWT and expiry.
@@ -607,6 +628,17 @@ paths:
value: {error: invalid credentials, code: unauthorized}
totp_required:
value: {error: TOTP code required, code: totp_required}
"403":
description: >
Login denied by policy. Credentials were valid but an operator
policy rule blocks this account from accessing the calling service.
content:
application/json:
schema:
$ref: "#/components/schemas/Error"
examples:
policy_denied:
value: {error: access denied by policy, code: policy_denied}
"429":
$ref: "#/components/responses/RateLimited"