fix(dashboard-auth): propagate next= through login page + PKCE cookie
The gate's _unauth_response set next=<path> on the /login redirect URL,
but nothing downstream read it: render_login_html ignored next=,
auth_login dropped it, and auth_callback read next= from its own query
string — which an IDP never sets on the callback URL (real IDPs only
echo back code+state). The _validate_post_login_target plumbing in the
callback was unreachable on the happy path, so users always landed on
"/" regardless of what they originally requested.
Worse: reading next= from the callback URL was a latent open-redirect
sink, since an attacker could craft /auth/callback?...&next=/admin and
have the server honour it post-auth.
Fix carries next= through the round trip on a server-controlled channel:
1. login_page reads request.query_params['next'] and passes it (post-
validation) to render_login_html.
2. render_login_html threads next= URL-encoded into each provider
button's href, with HTML-attribute escaping as defence in depth.
3. auth_login accepts ?next= as a query param, re-validates, and
appends it as a fourth segment (next=<urlquoted>) in the PKCE
cookie payload alongside provider/state/verifier.
4. auth_callback no longer accepts a next: str = "" query param. It
parses next= out of the PKCE cookie and validates that with the
same same-origin rules. Any attacker-supplied ?next= on the
callback URL is silently ignored — server-only carrier.
Test coverage adds three classes:
- TestAuthCallbackNext drives /login → /auth/login → IDP-bounce →
/auth/callback end-to-end without smuggling next= onto the callback
URL (which is what the previous tests did and why they didn't
catch the bug). Includes test_attacker_callback_next_param_is_ignored
to pin the security property that the URL value is never read.
- TestRenderLoginHtmlNext covers the rendering function at the
unit boundary so a regression that drops next_path is caught
without spinning up the full app.
- TestAuthLoginPkceCookieNext inspects the Set-Cookie header on
/auth/login responses so a regression in cookie encoding is caught
without driving the full round trip.
Mutation-tested: reverting auth_callback to read next= from the URL
trips 3 of 6 TestAuthCallbackNext tests (the safe-path and attacker-
hardening ones), confirming the suite discriminates between the cookie
read and the URL read.
This commit is contained in:
Ben
@@ -255,46 +255,229 @@ class TestNextSameOriginValidation:
|
||||
|
||||
|
||||
class TestAuthCallbackNext:
|
||||
def _drive_oauth(self, gated_app, *, next_path: str = ""):
|
||||
next_qs = f"&next={quote(next_path, safe='')}" if next_path else ""
|
||||
r1 = gated_app.get(
|
||||
f"/auth/login?provider=stub{next_qs}", follow_redirects=False
|
||||
)
|
||||
state = r1.headers["location"].split("state=")[1]
|
||||
# next is preserved by the route (it's in the original URL — but the
|
||||
# stub IDP returns to /auth/callback. We need to pass next as a
|
||||
# separate query param on the callback URL to simulate what a real
|
||||
# IDP would do via state-bound storage. For this test, the
|
||||
# /auth/callback handler reads `next` directly from its own query
|
||||
# string, so just append it.
|
||||
"""End-to-end next= propagation through a full OAuth round trip.
|
||||
|
||||
These tests drive the real flow exactly as the gate produces it:
|
||||
|
||||
1. unauth GET /sessions → 302 /login?next=%2Fsessions
|
||||
2. GET /login?next=%2Fsessions → HTML with provider buttons that
|
||||
carry next=%2Fsessions in their hrefs
|
||||
3. GET /auth/login?provider=stub&next=%2Fsessions → 302 to IDP +
|
||||
PKCE cookie carrying provider/state/verifier/next
|
||||
4. IDP returns to /auth/callback?code=...&state=... (NO next on
|
||||
the callback URL — real IDPs only echo back code+state)
|
||||
5. /auth/callback reads next from the PKCE cookie, validates it,
|
||||
and redirects there.
|
||||
|
||||
Discrimination: each test drives the flow without smuggling
|
||||
``next=`` onto the callback URL. Under the pre-fix code paths
|
||||
(/login ignored next=, /auth/login dropped it, /auth/callback read
|
||||
it from the wrong place), the callback always lands on ``/``. Only
|
||||
PKCE-cookie carriage produces the correct landing.
|
||||
"""
|
||||
|
||||
def _drive_oauth_via_login(
|
||||
self, gated_app, *, next_path: str = "",
|
||||
expect_next_in_button: bool = True,
|
||||
):
|
||||
"""Walk /login → /auth/login → IDP-bounce → /auth/callback like
|
||||
a real browser. ``next_path`` is the path the gate would have
|
||||
encoded for the user; nothing about the callback URL is
|
||||
smuggled. ``expect_next_in_button`` controls whether the
|
||||
rendered /login page is expected to thread next= into the
|
||||
provider button — False for cases where the same-origin
|
||||
validator drops the value (e.g. //evil.com, /login)."""
|
||||
login_path = "/login"
|
||||
if next_path:
|
||||
login_path = f"/login?next={quote(next_path, safe='')}"
|
||||
r_login = gated_app.get(login_path, follow_redirects=False)
|
||||
assert r_login.status_code == 200
|
||||
# Click the stub provider button. Real browsers parse the HTML;
|
||||
# we extract the href the page emitted, so a regression that
|
||||
# forgets to thread next= through the button will surface here.
|
||||
body = r_login.text
|
||||
# Each provider button is emitted as an <a class="provider-btn"
|
||||
# href="/auth/login?provider=stub..."> line.
|
||||
marker = 'href="'
|
||||
i = body.find('class="provider-btn"')
|
||||
assert i != -1, "no provider button in /login HTML"
|
||||
h = body.find(marker, i) + len(marker)
|
||||
j = body.find('"', h)
|
||||
href = body[h:j]
|
||||
# Critical: the href must carry next= when /login was given
|
||||
# next= AND the validator accepted it. (This is the property the
|
||||
# pre-fix render_login_html didn't satisfy.) For rejected
|
||||
# next= values, the validator drops them at the /login boundary
|
||||
# and the button href must NOT carry the rogue value.
|
||||
if next_path and expect_next_in_button:
|
||||
assert "next=" in href, (
|
||||
f"login button dropped next= (href={href!r})"
|
||||
)
|
||||
if next_path and not expect_next_in_button:
|
||||
assert "next=" not in href, (
|
||||
f"login button leaked rejected next= "
|
||||
f"(next_path={next_path!r}, href={href!r})"
|
||||
)
|
||||
|
||||
r_to_idp = gated_app.get(href, follow_redirects=False)
|
||||
assert r_to_idp.status_code == 302
|
||||
# Stub IDP "returns" code+state on the callback URL — same shape
|
||||
# as a real IDP. Critical: we do NOT append next= here.
|
||||
state = r_to_idp.headers["location"].split("state=")[1]
|
||||
return gated_app.get(
|
||||
f"/auth/callback?code=stub_code&state={state}{next_qs}",
|
||||
f"/auth/callback?code=stub_code&state={state}",
|
||||
follow_redirects=False,
|
||||
)
|
||||
|
||||
def test_callback_without_next_lands_at_root(self, gated_app):
|
||||
r = self._drive_oauth(gated_app)
|
||||
r = self._drive_oauth_via_login(gated_app)
|
||||
assert r.status_code == 302
|
||||
assert r.headers["location"] == "/"
|
||||
|
||||
def test_callback_with_safe_next_lands_there(self, gated_app):
|
||||
r = self._drive_oauth(gated_app, next_path="/sessions")
|
||||
r = self._drive_oauth_via_login(gated_app, next_path="/sessions")
|
||||
assert r.status_code == 302
|
||||
assert r.headers["location"] == "/sessions"
|
||||
|
||||
def test_callback_with_query_string_in_next(self, gated_app):
|
||||
r = self._drive_oauth(gated_app, next_path="/sessions?page=2")
|
||||
r = self._drive_oauth_via_login(
|
||||
gated_app, next_path="/sessions?page=2"
|
||||
)
|
||||
assert r.status_code == 302
|
||||
assert r.headers["location"] == "/sessions?page=2"
|
||||
|
||||
def test_callback_rejects_open_redirect(self, gated_app):
|
||||
# Attacker provides ``next=//evil.com`` hoping for an open redirect
|
||||
# after successful auth. Validator drops it; user lands at "/".
|
||||
r = self._drive_oauth(gated_app, next_path="//evil.com/steal")
|
||||
# Attacker tries to inject ``next=//evil.com`` at the /login
|
||||
# boundary, hoping it survives to the callback redirect. The
|
||||
# /login validator drops it before it reaches the button href
|
||||
# (and therefore the cookie), so the callback never sees it and
|
||||
# the user lands at "/".
|
||||
r = self._drive_oauth_via_login(
|
||||
gated_app, next_path="//evil.com/steal",
|
||||
expect_next_in_button=False,
|
||||
)
|
||||
assert r.status_code == 302
|
||||
assert r.headers["location"] == "/"
|
||||
|
||||
def test_callback_rejects_login_loop(self, gated_app):
|
||||
r = self._drive_oauth(gated_app, next_path="/login")
|
||||
r = self._drive_oauth_via_login(
|
||||
gated_app, next_path="/login",
|
||||
expect_next_in_button=False,
|
||||
)
|
||||
assert r.status_code == 302
|
||||
assert r.headers["location"] == "/"
|
||||
|
||||
def test_attacker_callback_next_param_is_ignored(self, gated_app):
|
||||
"""Hardening: even if an attacker crafts a callback URL with a
|
||||
rogue ``next=`` query parameter, the server reads from the PKCE
|
||||
cookie (server-set) and ignores the URL value. This pins the
|
||||
fix against a regression that re-introduces the URL read."""
|
||||
# Drive a clean login with no next=.
|
||||
r_login = gated_app.get("/login", follow_redirects=False)
|
||||
assert r_login.status_code == 200
|
||||
r_to_idp = gated_app.get(
|
||||
"/auth/login?provider=stub", follow_redirects=False
|
||||
)
|
||||
state = r_to_idp.headers["location"].split("state=")[1]
|
||||
# Attacker appends next=/internal-admin to the callback URL.
|
||||
r = gated_app.get(
|
||||
f"/auth/callback?code=stub_code&state={state}"
|
||||
f"&next={quote('/internal-admin', safe='')}",
|
||||
follow_redirects=False,
|
||||
)
|
||||
assert r.status_code == 302
|
||||
# No next= was in the PKCE cookie, so landing must be "/" —
|
||||
# NOT /internal-admin.
|
||||
assert r.headers["location"] == "/"
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Unit-level coverage: render_login_html threads next= into provider buttons
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
class TestRenderLoginHtmlNext:
|
||||
"""Cover ``render_login_html`` directly so a regression that drops
|
||||
the ``next_path`` parameter is caught at the function boundary, not
|
||||
only via the full integration walk."""
|
||||
|
||||
def setup_method(self):
|
||||
clear_providers()
|
||||
register_provider(StubAuthProvider())
|
||||
|
||||
def teardown_method(self):
|
||||
clear_providers()
|
||||
|
||||
def test_no_next_emits_plain_button(self):
|
||||
from hermes_cli.dashboard_auth.login_page import render_login_html
|
||||
html_out = render_login_html()
|
||||
assert 'href="/auth/login?provider=stub"' in html_out
|
||||
assert "next=" not in html_out
|
||||
|
||||
def test_next_threaded_url_encoded(self):
|
||||
from hermes_cli.dashboard_auth.login_page import render_login_html
|
||||
html_out = render_login_html(next_path="/sessions?page=2")
|
||||
# next= is URL-encoded — quote(safe='') turns "/" into "%2F",
|
||||
# "?" into "%3F", "=" into "%3D". The encoded value never
|
||||
# contains an "&" so the raw "&" separator in the href is
|
||||
# unambiguous.
|
||||
assert "next=%2Fsessions%3Fpage%3D2" in html_out
|
||||
assert "provider=stub&next=" in html_out
|
||||
|
||||
def test_next_with_html_metacharacters_is_escaped(self):
|
||||
"""Defence in depth: even though the caller validates next_path,
|
||||
we still HTML-escape the rendered value so a regression in the
|
||||
caller can't trivially produce an HTML-injection sink."""
|
||||
from hermes_cli.dashboard_auth.login_page import render_login_html
|
||||
# `"` in a path is already URL-encoded by quote() to %22, so it
|
||||
# never reaches the HTML escaper as a raw quote. This test pins
|
||||
# both layers: quote() does its job AND escape() does its.
|
||||
html_out = render_login_html(next_path='/x"injected')
|
||||
assert '"injected' not in html_out
|
||||
assert "%22injected" in html_out
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Unit-level coverage: /auth/login persists next= into the PKCE cookie
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
class TestAuthLoginPkceCookieNext:
|
||||
"""Cover the ``/auth/login`` route's PKCE cookie payload directly.
|
||||
|
||||
The cookie is the round-trip carrier for ``next=``; if /auth/login
|
||||
forgets to encode it, the callback has no path to honour even when
|
||||
everything else is wired correctly.
|
||||
"""
|
||||
|
||||
def test_no_next_query_omits_next_segment(self, gated_app):
|
||||
r = gated_app.get(
|
||||
"/auth/login?provider=stub", follow_redirects=False
|
||||
)
|
||||
assert r.status_code == 302
|
||||
cookies = r.headers.get_list("set-cookie")
|
||||
pkce = next(c for c in cookies if c.startswith("hermes_session_pkce="))
|
||||
assert "next=" not in pkce
|
||||
|
||||
def test_safe_next_query_encoded_into_cookie(self, gated_app):
|
||||
r = gated_app.get(
|
||||
f"/auth/login?provider=stub&next={quote('/sessions', safe='')}",
|
||||
follow_redirects=False,
|
||||
)
|
||||
cookies = r.headers.get_list("set-cookie")
|
||||
pkce = next(c for c in cookies if c.startswith("hermes_session_pkce="))
|
||||
# ``next=`` segment present, URL-encoded.
|
||||
assert "next=%2Fsessions" in pkce
|
||||
|
||||
def test_unsafe_next_query_dropped_from_cookie(self, gated_app):
|
||||
"""The validator at /auth/login refuses //evil.com BEFORE
|
||||
storing it. Defence in depth: even if a regression leaks next=
|
||||
through /login's button rendering, /auth/login is the second
|
||||
boundary."""
|
||||
r = gated_app.get(
|
||||
f"/auth/login?provider=stub&next={quote('//evil.com/x', safe='')}",
|
||||
follow_redirects=False,
|
||||
)
|
||||
cookies = r.headers.get_list("set-cookie")
|
||||
pkce = next(c for c in cookies if c.startswith("hermes_session_pkce="))
|
||||
assert "next=" not in pkce
|
||||
|
||||
Reference in New Issue
Block a user