russell@unturf.com
decacb5dbd
systemd-0004: seccomp_load_syscall_filter_set() in src/shared/seccomp-util.c uses strv_contains(added, name) — O(|added|) linear scan — inside NULSTR_FOREACH over ~537 KNOWN syscalls. On x86_64 (3 arches): ~484,000 string comparisons per service start with SeccompFilter=. Sibling function seccomp_load_syscall_filter_set_raw() already uses hashmap_contains for O(1); this function was left behind. Fix: build Set* from added strv before the NULSTR_FOREACH loop. MEDIUM severity. dbus-0001: bus_client_policy_optimize() in bus/policy.c iterates R rules and for each blanket deny/allow calls remove_rules_by_type_up_to() which scans backward from current position to head — O(R^2) total per new connection creation. At R=100 rules (realistic system bus): ~10,000 comparisons per connect. Fix: single O(R) reverse pass tracking last-seen blanket per rule type. MEDIUM. dbus 5-MOAD summary: MOAD-0001: dbus-0001 DEFECT (policy optimize O(R^2)) MOAD-0002: CLEAN (BusContext is standard daemon context, not a god object) MOAD-0003: CLEAN (single-threaded event loop, no thread-local state) MOAD-0004: CLEAN (_dbus_verbose is no-op in production builds) MOAD-0005: CLEAN (pending_activations hash table coalesces duplicate requests)
110 lines
4 KiB
Diff
110 lines
4 KiB
Diff
# UNDF: UNDF-PENDING
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--- a/bus/policy.c
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+++ b/bus/policy.c
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@@ -780,38 +780,58 @@ remove_rules_by_type_up_to (BusClientPolicy *policy,
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void
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bus_client_policy_optimize (BusClientPolicy *policy)
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{
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- DBusList *link;
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+ /* Replace O(R^2) backward-scan optimization with a single O(R) reverse pass.
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+ *
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+ * Original approach: for each blanket rule, call remove_rules_by_type_up_to()
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+ * which walks from head to the current position — O(R) inner loop, O(R^2) total.
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+ *
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+ * Fixed approach: iterate from tail to head. The first (rightmost) blanket rule
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+ * of each type supersedes all earlier rules of the same type. Track the last
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+ * seen blanket per type and remove all preceding same-type rules in one pass.
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+ */
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+ DBusList *link;
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+ dbus_bool_t seen_send_blanket = FALSE;
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+ dbus_bool_t seen_receive_blanket = FALSE;
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+ dbus_bool_t seen_own_blanket = FALSE;
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_dbus_verbose ("Optimizing policy with %d rules\n",
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_dbus_list_get_length (&policy->rules));
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-
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- link = _dbus_list_get_first_link (&policy->rules);
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+
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+ /* Walk from tail to head. Remove any rule that is shadowed by a later
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+ * blanket rule of the same type. */
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+ link = _dbus_list_get_last_link (&policy->rules);
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while (link != NULL)
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{
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BusPolicyRule *rule;
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- DBusList *next;
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- dbus_bool_t remove_preceding;
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+ DBusList *prev;
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+ dbus_bool_t is_blanket;
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+ dbus_bool_t already_shadowed;
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- next = _dbus_list_get_next_link (&policy->rules, link);
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+ prev = _dbus_list_get_prev_link (&policy->rules, link);
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rule = link->data;
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-
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- remove_preceding = FALSE;
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- _dbus_assert (rule != NULL);
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-
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+ is_blanket = FALSE;
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+ already_shadowed = FALSE;
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+
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switch (rule->type)
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{
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case BUS_POLICY_RULE_SEND:
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- remove_preceding =
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- rule->d.send.message_type == DBUS_MESSAGE_TYPE_INVALID &&
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+ is_blanket = (rule->d.send.message_type == DBUS_MESSAGE_TYPE_INVALID &&
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rule->d.send.path == NULL &&
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rule->d.send.interface == NULL &&
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rule->d.send.member == NULL &&
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rule->d.send.error == NULL &&
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- rule->d.send.destination == NULL;
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+ rule->d.send.destination == NULL);
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+ already_shadowed = seen_send_blanket && !is_blanket;
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+ if (is_blanket) seen_send_blanket = TRUE;
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break;
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case BUS_POLICY_RULE_RECEIVE:
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- remove_preceding =
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- rule->d.receive.message_type == DBUS_MESSAGE_TYPE_INVALID &&
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+ is_blanket = (rule->d.receive.message_type == DBUS_MESSAGE_TYPE_INVALID &&
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rule->d.receive.path == NULL &&
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rule->d.receive.interface == NULL &&
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rule->d.receive.member == NULL &&
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rule->d.receive.error == NULL &&
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- rule->d.receive.origin == NULL;
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+ rule->d.receive.origin == NULL);
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+ already_shadowed = seen_receive_blanket && !is_blanket;
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+ if (is_blanket) seen_receive_blanket = TRUE;
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break;
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case BUS_POLICY_RULE_OWN:
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- remove_preceding =
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- rule->d.own.service_name == NULL;
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+ is_blanket = (rule->d.own.service_name == NULL);
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+ already_shadowed = seen_own_blanket && !is_blanket;
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+ if (is_blanket) seen_own_blanket = TRUE;
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break;
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- /* The other rule types don't appear in this list */
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case BUS_POLICY_RULE_USER:
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case BUS_POLICY_RULE_GROUP:
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default:
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_dbus_assert_not_reached ("invalid rule");
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break;
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}
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- if (remove_preceding)
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- remove_rules_by_type_up_to (policy, rule->type,
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- link);
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-
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- link = next;
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+ if (already_shadowed)
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+ {
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+ /* This specific rule can never fire — remove it in O(1). */
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+ _dbus_list_remove_link (&policy->rules, link);
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+ bus_policy_rule_unref (rule);
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+ }
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+
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+ link = prev;
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}
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_dbus_verbose ("After optimization, policy has %d rules\n",
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