From 5a20855d6054ebaae590c09262b328d957cc1fc2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jan=20Pokorn=C3=BD?= Date: Thu, 3 Nov 2016 11:16:37 +0100 Subject: [PATCH] High: libcrmcommon: fix CVE-2016-7035 (improper IPC guarding) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It was discovered that at some not so uncommon circumstances, some pacemaker daemons could be talked to, via libqb-facilitated IPC, by unprivileged clients due to flawed authorization decision. Depending on the capabilities of affected daemons, this might equip unauthorized user with local privilege escalation or up to cluster-wide remote execution of possibly arbitrary commands when such user happens to reside at standard or remote/guest cluster node, respectively. The original vulnerability was introduced in an attempt to allow unprivileged IPC clients to clean up the file system materialized leftovers in case the server (otherwise responsible for the lifecycle of these files) crashes. While the intended part of such behavior is now effectively voided (along with the unintended one), a best-effort fix to address this corner case systemically at libqb is coming along (https://github.com/ClusterLabs/libqb/pull/231). Affected versions: 1.1.10-rc1 (2013-04-17) - 1.1.15 (2016-06-21) Impact: Important CVSSv3 ranking: 8.8 : AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H Credits for independent findings, in chronological order: Jan "poki" Pokorný, of Red Hat Alain Moulle, of ATOS/BULL --- lib/common/ipc.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/lib/common/ipc.c b/lib/common/ipc.c index f060fcd..2949837 100644 --- a/lib/common/ipc.c +++ b/lib/common/ipc.c @@ -293,7 +293,6 @@ crm_client_disconnect_all(qb_ipcs_service_t *service) crm_client_t * crm_client_new(qb_ipcs_connection_t * c, uid_t uid_client, gid_t gid_client) { - static uid_t uid_server = 0; static gid_t gid_cluster = 0; crm_client_t *client = NULL; @@ -304,7 +303,6 @@ crm_client_new(qb_ipcs_connection_t * c, uid_t uid_client, gid_t gid_client) } if (gid_cluster == 0) { - uid_server = getuid(); if(crm_user_lookup(CRM_DAEMON_USER, NULL, &gid_cluster) < 0) { static bool have_error = FALSE; if(have_error == FALSE) { @@ -314,16 +312,10 @@ crm_client_new(qb_ipcs_connection_t * c, uid_t uid_client, gid_t gid_client) } } - if(gid_cluster != 0 && gid_client != 0) { - uid_t best_uid = -1; /* Passing -1 to chown(2) means don't change */ - - if(uid_client == 0 || uid_server == 0) { /* Someone is priveliged, but the other may not be */ - best_uid = QB_MAX(uid_client, uid_server); - crm_trace("Allowing user %u to clean up after disconnect", best_uid); - } - + if (uid_client != 0) { crm_trace("Giving access to group %u", gid_cluster); - qb_ipcs_connection_auth_set(c, best_uid, gid_cluster, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP); + /* Passing -1 to chown(2) means don't change */ + qb_ipcs_connection_auth_set(c, -1, gid_cluster, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP); } crm_client_init(); -- 2.4.11