From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-44.mimecast.com (us-smtp-delivery-44.mimecast.com [207.211.30.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0064748E for ; Tue, 20 Sep 2022 18:09:20 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-315-DWruCP5jNLe8nJwirNOEOA-1; Tue, 20 Sep 2022 14:09:16 -0400 X-MC-Unique: DWruCP5jNLe8nJwirNOEOA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A8DD18001B8; Tue, 20 Sep 2022 18:09:14 +0000 (UTC) Received: from comp-core-i7-2640m-0182e6.redhat.com (unknown [10.40.208.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id 384462166B26; Tue, 20 Sep 2022 18:09:13 +0000 (UTC) From: Alexey Gladkov To: LKML , Linux Containers Cc: Andrew Morton , Christian Brauner , "Eric W . Biederman" , Kees Cook , Manfred Spraul Subject: [PATCH v2 2/3] sysctl: Allow to change limits for posix messages queues Date: Tue, 20 Sep 2022 20:08:21 +0200 Message-Id: <207698b81c7e55b3d00d2476b081a8fee5d369f6.1663696560.git.legion@kernel.org> In-Reply-To: References: Precedence: bulk X-Mailing-List: containers@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 All parameters of posix messages queues (queues_max/msg_max/msgsize_max) end up being limited by RLIMIT_MSGQUEUE. The code in mqueue_get_inode is where that limiting happens. The RLIMIT_MSGQUEUE is bound to the user namespace and is counted hierarchically. We can allow root in the user namespace to modify the posix messages queues parameters. Signed-off-by: Alexey Gladkov --- ipc/mq_sysctl.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/ipc/mq_sysctl.c b/ipc/mq_sysctl.c index fbf6a8b93a26..5e573c657775 100644 --- a/ipc/mq_sysctl.c +++ b/ipc/mq_sysctl.c @@ -12,6 +12,7 @@ #include #include #include +#include static int msg_max_limit_min = MIN_MSGMAX; static int msg_max_limit_max = HARD_MSGMAX; @@ -76,8 +77,45 @@ static int set_is_seen(struct ctl_table_set *set) return ¤t->nsproxy->ipc_ns->mq_set == set; } +static void mq_set_ownership(struct ctl_table_header *head, + struct ctl_table *table, + kuid_t *uid, kgid_t *gid) +{ + struct ipc_namespace *ns = + container_of(head->set, struct ipc_namespace, mq_set); + + kuid_t ns_root_uid = make_kuid(ns->user_ns, 0); + kgid_t ns_root_gid = make_kgid(ns->user_ns, 0); + + *uid = uid_valid(ns_root_uid) ? ns_root_uid : GLOBAL_ROOT_UID; + *gid = gid_valid(ns_root_gid) ? ns_root_gid : GLOBAL_ROOT_GID; +} + +static int mq_permissions(struct ctl_table_header *head, struct ctl_table *table) +{ + struct ipc_namespace *ns = + container_of(head->set, struct ipc_namespace, mq_set); + int mode = table->mode; + kuid_t ns_root_uid; + kgid_t ns_root_gid; + + mq_set_ownership(head, table, &ns_root_uid, &ns_root_gid); + + if (uid_eq(current_euid(), ns_root_uid)) + mode >>= 6; + + if (in_egroup_p(ns_root_gid)) + mode >>= 3; + + mode &= 7; + + return (mode << 6) | (mode << 3) | mode; +} + static struct ctl_table_root set_root = { .lookup = set_lookup, + .permissions = mq_permissions, + .set_ownership = mq_set_ownership, }; bool setup_mq_sysctls(struct ipc_namespace *ns) -- 2.33.4