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From 29de632674473729d1e9497b6fe47e7c88682ed9 Mon Sep 17 00:00:00 2001
From: Riccardo Schirone <rschiron@redhat.com>
Date: Mon, 4 Feb 2019 14:29:09 +0100
Subject: [PATCH 1/3] Refuse dbus message paths longer than BUS_PATH_SIZE_MAX
limit.
Even though the dbus specification does not enforce any length limit on the
path of a dbus message, having to analyze too long strings in PID1 may be
time-consuming and it may have security impacts.
In any case, the limit is set so high that real-life applications should not
have a problem with it.
---
src/libsystemd/sd-bus/bus-internal.c | 2 +-
src/libsystemd/sd-bus/bus-internal.h | 4 ++++
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/libsystemd/sd-bus/bus-internal.c b/src/libsystemd/sd-bus/bus-internal.c
index 40acae2133..598b7f110c 100644
--- a/src/libsystemd/sd-bus/bus-internal.c
+++ b/src/libsystemd/sd-bus/bus-internal.c
@@ -43,7 +43,7 @@ bool object_path_is_valid(const char *p) {
if (slash)
return false;
- return true;
+ return (q - p) <= BUS_PATH_SIZE_MAX;
}
char* object_path_startswith(const char *a, const char *b) {
diff --git a/src/libsystemd/sd-bus/bus-internal.h b/src/libsystemd/sd-bus/bus-internal.h
index f208b294d8..a8d61bf72a 100644
--- a/src/libsystemd/sd-bus/bus-internal.h
+++ b/src/libsystemd/sd-bus/bus-internal.h
@@ -332,6 +332,10 @@ struct sd_bus {
#define BUS_MESSAGE_SIZE_MAX (128*1024*1024)
#define BUS_AUTH_SIZE_MAX (64*1024)
+/* Note that the D-Bus specification states that bus paths shall have no size limit. We enforce here one
+ * anyway, since truly unbounded strings are a security problem. The limit we pick is relatively large however,
+ * to not clash unnecessarily with real-life applications. */
+#define BUS_PATH_SIZE_MAX (64*1024)
#define BUS_CONTAINER_DEPTH 128
--
2.20.1
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