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From ac9c51b72213bcea3dc9cea330d4c5fce9c4470e Mon Sep 17 00:00:00 2001
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From: Riccardo Schirone <rschiron@redhat.com>
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Date: Mon, 4 Feb 2019 14:29:09 +0100
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Subject: [PATCH] Refuse dbus message paths longer than BUS_PATH_SIZE_MAX
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limit.
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Even though the dbus specification does not enforce any length limit on the
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path of a dbus message, having to analyze too long strings in PID1 may be
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time-consuming and it may have security impacts.
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In any case, the limit is set so high that real-life applications should not
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have a problem with it.
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(cherry-picked from commit 61397a60d98e368a5720b37e83f3169e3eb511c4)
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Related: #1678641
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---
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src/libsystemd/sd-bus/bus-internal.c | 2 +-
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src/libsystemd/sd-bus/bus-internal.h | 4 ++++
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2 files changed, 5 insertions(+), 1 deletion(-)
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diff --git a/src/libsystemd/sd-bus/bus-internal.c b/src/libsystemd/sd-bus/bus-internal.c
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index 7bb653338d..35e0b668ee 100644
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--- a/src/libsystemd/sd-bus/bus-internal.c
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+++ b/src/libsystemd/sd-bus/bus-internal.c
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@@ -45,7 +45,7 @@ bool object_path_is_valid(const char *p) {
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if (slash)
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return false;
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- return true;
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+ return (q - p) <= BUS_PATH_SIZE_MAX;
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}
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char* object_path_startswith(const char *a, const char *b) {
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diff --git a/src/libsystemd/sd-bus/bus-internal.h b/src/libsystemd/sd-bus/bus-internal.h
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index 2087ef8eeb..90e6028983 100644
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--- a/src/libsystemd/sd-bus/bus-internal.h
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+++ b/src/libsystemd/sd-bus/bus-internal.h
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@@ -333,6 +333,10 @@ struct sd_bus {
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#define BUS_MESSAGE_SIZE_MAX (128*1024*1024)
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#define BUS_AUTH_SIZE_MAX (64*1024)
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+/* Note that the D-Bus specification states that bus paths shall have no size limit. We enforce here one
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+ * anyway, since truly unbounded strings are a security problem. The limit we pick is relatively large however,
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+ * to not clash unnecessarily with real-life applications. */
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+#define BUS_PATH_SIZE_MAX (64*1024)
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#define BUS_CONTAINER_DEPTH 128
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