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bus-polkit: allow to auth. a bus call for multiple actions

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In #20155, verify_shutdown_creds() needs to authenticate for both
org.freedesktop.login1.hibernate-multiple-sessions and
org.freedesktop.login1.hibernate-ignore-inhibit . Previously, the second
authentication attempt would fail with -ESTALE.

Fixes #20155.
This commit is contained in:
David Tardon
2023-07-13 16:40:05 +02:00
parent 959301cf9f
commit 2f50a4f38f
1 changed files with 87 additions and 53 deletions
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src/shared/bus-polkit.c
+87 -53
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@@ -170,6 +170,8 @@ int bus_test_polkit(
typedef struct AsyncPolkitQueryAction {
char *action;
char **details;
LIST_FIELDS(struct AsyncPolkitQueryAction, authorized);
} AsyncPolkitQueryAction;
static AsyncPolkitQueryAction *async_polkit_query_action_free(AsyncPolkitQueryAction *a) {
@@ -185,6 +187,8 @@ static AsyncPolkitQueryAction *async_polkit_query_action_free(AsyncPolkitQueryAc
DEFINE_TRIVIAL_CLEANUP_FUNC(AsyncPolkitQueryAction*, async_polkit_query_action_free);
typedef struct AsyncPolkitQuery {
unsigned n_ref;
AsyncPolkitQueryAction *action;
sd_bus_message *request;
@@ -193,13 +197,15 @@ typedef struct AsyncPolkitQuery {
Hashmap *registry;
sd_event_source *defer_event_source;
AsyncPolkitQueryAction *authorized_action;
LIST_HEAD(AsyncPolkitQueryAction, authorized_actions);
AsyncPolkitQueryAction *denied_action;
AsyncPolkitQueryAction *error_action;
sd_bus_error error;
} AsyncPolkitQuery;
static AsyncPolkitQuery *async_polkit_query_free(AsyncPolkitQuery *q) {
AsyncPolkitQueryAction *a;
if (!q)
return NULL;
@@ -214,7 +220,11 @@ static AsyncPolkitQuery *async_polkit_query_free(AsyncPolkitQuery *q) {
sd_event_source_disable_unref(q->defer_event_source);
async_polkit_query_action_free(q->authorized_action);
while ((a = q->authorized_actions)) {
LIST_REMOVE(authorized, q->authorized_actions, a);
async_polkit_query_action_free(a);
}
async_polkit_query_action_free(q->denied_action);
async_polkit_query_action_free(q->error_action);
@@ -223,7 +233,8 @@ static AsyncPolkitQuery *async_polkit_query_free(AsyncPolkitQuery *q) {
return mfree(q);
}
DEFINE_TRIVIAL_CLEANUP_FUNC(AsyncPolkitQuery*, async_polkit_query_free);
DEFINE_PRIVATE_TRIVIAL_REF_UNREF_FUNC(AsyncPolkitQuery, async_polkit_query, async_polkit_query_free);
DEFINE_TRIVIAL_CLEANUP_FUNC(AsyncPolkitQuery*, async_polkit_query_unref);
static int async_polkit_defer(sd_event_source *s, void *userdata) {
AsyncPolkitQuery *q = ASSERT_PTR(userdata);
@@ -233,7 +244,7 @@ static int async_polkit_defer(sd_event_source *s, void *userdata) {
/* This is called as idle event source after we processed the async polkit reply, hopefully after the
* method call we re-enqueued has been properly processed. */
async_polkit_query_free(q);
async_polkit_query_unref(q);
return 0;
}
@@ -271,13 +282,14 @@ static int async_polkit_read_reply(sd_bus_message *reply, AsyncPolkitQuery *q) {
if (r < 0)
return r;
assert(!q->authorized_action);
/* It's currently expected that processing of a DBus message shall be interrupted on the first
* auth. error */
assert(!q->denied_action);
assert(!q->error_action);
assert(!sd_bus_error_is_set(&q->error));
if (authorized)
q->authorized_action = TAKE_PTR(a);
LIST_PREPEND(authorized, q->authorized_actions, TAKE_PTR(a));
else if (challenge) {
q->error_action = TAKE_PTR(a);
return sd_bus_error_set(&q->error, SD_BUS_ERROR_INTERACTIVE_AUTHORIZATION_REQUIRED, "Interactive authentication required.");
@@ -307,14 +319,19 @@ static int async_polkit_process_reply(sd_bus_message *reply, AsyncPolkitQuery *q
* We install an idle event loop event to clean-up the PolicyKit request data when we are idle again,
* i.e. after the second time the message is processed is complete. */
assert(!q->defer_event_source);
r = sd_event_add_defer(sd_bus_get_event(sd_bus_message_get_bus(reply)), &q->defer_event_source, async_polkit_defer, q);
if (r < 0)
return r;
if (!q->defer_event_source) {
r = sd_event_add_defer(
sd_bus_get_event(sd_bus_message_get_bus(reply)),
&q->defer_event_source,
async_polkit_defer,
q);
if (r < 0)
return r;
r = sd_event_source_set_priority(q->defer_event_source, SD_EVENT_PRIORITY_IDLE);
if (r < 0)
return r;
r = sd_event_source_set_priority(q->defer_event_source, SD_EVENT_PRIORITY_IDLE);
if (r < 0)
return r;
}
r = sd_event_source_set_enabled(q->defer_event_source, SD_EVENT_ONESHOT);
if (r < 0)
@@ -341,7 +358,7 @@ static int async_polkit_callback(sd_bus_message *reply, void *userdata, sd_bus_e
if (r < 0) {
log_debug_errno(r, "Processing asynchronous PolicyKit reply failed, ignoring: %m");
(void) sd_bus_reply_method_errno(q->request, r, NULL);
async_polkit_query_free(q);
async_polkit_query_unref(q);
}
return r;
}
@@ -356,17 +373,17 @@ _pure_ static int async_polkit_query_check_action(
assert(action);
assert(ret_error);
if (q->authorized_action)
/* If the operation we want to authenticate changed between the first and the second time,
* let's not use this authentication, it might be out of date as the object and context we
* operate on might have changed. */
return streq(q->authorized_action->action, action) && strv_equal(q->action->details, (char**) details) ? 1 : -ESTALE;
LIST_FOREACH(authorized, a, q->authorized_actions)
if (streq(a->action, action) && strv_equal(a->details, (char**) details))
return 1;
if (q->error_action)
if (q->error_action && streq(q->error_action->action, action))
return sd_bus_error_copy(ret_error, &q->error);
assert(q->denied_action);
return -EACCES;
if (q->denied_action && streq(q->denied_action->action, action))
return -EACCES;
return 0;
}
#endif
@@ -396,21 +413,26 @@ _pure_ static int async_polkit_query_check_action(
*
* A step-by-step description of how it works:
*
* 1. A D-Bus method handler calls bus_verify_polkit_async(), passing it the D-Bus message being
* processed and the polkit action to verify.
* 2. bus_verify_polkit_async() checks the registry for the message and action combination. Let's
* assume this is the first call, so it finds nothing.
* 3. A new AsyncPolkitQuery object is created and an async. D-Bus call to polkit is made. The
* function then returns 0. The method handler returns 1 to tell sd-bus that the processing of
* 1. A D-Bus method handler calls bus_verify_polkit_async(), passing it the D-Bus message being
* processed and the polkit action to verify.
* 2. bus_verify_polkit_async() checks the registry for an existing query object associated with the
* message. Let's assume this is the first call, so it finds nothing.
* 3. A new AsyncPolkitQuery object is created and an async. D-Bus call to polkit is made. The
* function then returns 0. The method handler returns 1 to tell sd-bus that the processing of
* the message has been interrupted.
* 4. (Later) A reply from polkit is received and async_polkit_callback() is called.
* 5. async_polkit_callback() reads the reply and stores result into the passed query.
* 6. async_polkit_callback() enqueues the original message again.
* 7. (Later) The same D-Bus method handler is called for the same message. It calls
* bus_verify_polkit_async() again.
* 8. bus_verify_polkit_async() checks the registry for the message and action combination. It finds
* an existing query and returns its result.
* 9. The method handler continues processing of the message.
* 4. (Later) A reply from polkit is received and async_polkit_callback() is called.
* 5. async_polkit_callback() reads the reply and stores its result in the passed query.
* 6. async_polkit_callback() enqueues the original message again.
* 7. (Later) The same D-Bus method handler is called for the same message. It calls
* bus_verify_polkit_async() again.
* 8. bus_verify_polkit_async() checks the registry for an existing query object associated with the
* message. It finds one and returns the result for the action.
* 9. The method handler continues processing of the message. If there's another action that needs
* to be verified:
* 10. bus_verify_polkit_async() is called again for the new action. The registry already contains a
* query for the message, but the new action hasn't been seen yet, hence steps 4-8 are repeated.
* 11. (In the method handler again.) bus_verify_polkit_async() returns query results for both
* actions and the processing continues as in step 9.
*
* Memory handling:
*
@@ -425,6 +447,7 @@ _pure_ static int async_polkit_query_check_action(
*
* -> foo_method(m)
* -> bus_verify_polkit_async(m, a)
* -> async_polkit_query_ref(q)
* -> bus_call_method_async(q)
* <- bus_verify_polkit_async(m, a) = 0
* <- foo_method(m) = 1
@@ -438,10 +461,11 @@ _pure_ static int async_polkit_query_check_action(
* -> bus_verify_polkit_async(m, a)
* <- bus_verify_polkit_async(m, a) = 1/-EACCES/error
* ...
* // possibly another call to bus_verify_polkit_async with action a2
* <- foo_method(m)
* ...
* -> async_polkit_defer(q)
* -> async_polkit_query_free(q)
* -> async_polkit_query_unref(q)
* <- async_polkit_defer(q)
*/
@@ -467,10 +491,13 @@ int bus_verify_polkit_async(
#if ENABLE_POLKIT
AsyncPolkitQuery *q = hashmap_get(*registry, call);
/* This is the second invocation of this function, and there's already a response from
* polkit, let's process it */
if (q)
return async_polkit_query_check_action(q, action, details, ret_error);
/* This is a repeated invocation of this function, hence let's check if we've already got
* a response from polkit for this action */
if (q) {
r = async_polkit_query_check_action(q, action, details, ret_error);
if (r != 0)
return r;
}
#endif
r = sd_bus_query_sender_privilege(call, capability);
@@ -481,7 +508,7 @@ int bus_verify_polkit_async(
#if ENABLE_POLKIT
_cleanup_(sd_bus_message_unrefp) sd_bus_message *pk = NULL;
_cleanup_(async_polkit_query_freep) AsyncPolkitQuery *q_new = NULL;
_cleanup_(async_polkit_query_unrefp) AsyncPolkitQuery *q_new = NULL;
int c = sd_bus_message_get_allow_interactive_authorization(call);
if (c < 0)
@@ -497,14 +524,19 @@ int bus_verify_polkit_async(
if (r < 0)
return r;
q = q_new = new(AsyncPolkitQuery, 1);
if (!q)
return -ENOMEM;
if (!q) {
q = q_new = new(AsyncPolkitQuery, 1);
if (!q)
return -ENOMEM;
*q = (AsyncPolkitQuery) {
.request = sd_bus_message_ref(call),
};
*q = (AsyncPolkitQuery) {
.n_ref = 1,
.request = sd_bus_message_ref(call),
};
} else
async_polkit_query_ref(q);
assert(!q->action);
q->action = new(AsyncPolkitQueryAction, 1);
if (!q->action)
return -ENOMEM;
@@ -516,11 +548,13 @@ int bus_verify_polkit_async(
if (!q->action->action || !q->action->details)
return -ENOMEM;
r = hashmap_put(*registry, call, q);
if (r < 0)
return r;
if (!q->registry) {
r = hashmap_put(*registry, call, q);
if (r < 0)
return r;
q->registry = *registry;
q->registry = *registry;
}
r = sd_bus_call_async(call->bus, &q->slot, pk, async_polkit_callback, q, 0);
if (r < 0)
@@ -536,7 +570,7 @@ int bus_verify_polkit_async(
Hashmap *bus_verify_polkit_async_registry_free(Hashmap *registry) {
#if ENABLE_POLKIT
return hashmap_free_with_destructor(registry, async_polkit_query_free);
return hashmap_free_with_destructor(registry, async_polkit_query_unref);
#else
assert(hashmap_isempty(registry));
return hashmap_free(registry);