From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Eric W. Biederman" Subject: [PATCH 08/10] cgroupns: Add a limit on the number of cgroup namespaces Date: Tue, 19 Jul 2016 20:21:36 -0500 Message-ID: <20160720012138.7894-8-ebiederm@xmission.com> References: <8737n5dscy.fsf@x220.int.ebiederm.org> <20160720012138.7894-1-ebiederm@xmission.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160720012138.7894-1-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Linux Containers Cc: Kees Cook , Andy Lutomirski , Seth Forshee , Nikolay Borisov , "Eric W. Biederman" , Jann Horn List-Id: containers.vger.kernel.org Signed-off-by: "Eric W. Biederman" --- include/linux/user_namespace.h | 1 + kernel/cgroup.c | 15 +++++++++++++++ kernel/user_namespace.c | 1 + 3 files changed, 17 insertions(+) diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 19f9ee590062..3ad3cb505781 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -27,6 +27,7 @@ enum ucounts { UCOUNT_PID_NAMESPACES, UCOUNT_UTS_NAMESPACES, UCOUNT_IPC_NAMESPACES, + UCOUNT_CGROUP_NAMESPACES, UCOUNT_MAX, }; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 86cb5c6e8932..240eec43390b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -6260,6 +6260,16 @@ void cgroup_sk_free(struct sock_cgroup_data *skcd) /* cgroup namespaces */ +static bool inc_cgroup_namespaces(struct user_namespace *ns) +{ + return inc_ucount(ns, UCOUNT_CGROUP_NAMESPACES); +} + +static void dec_cgroup_namespaces(struct user_namespace *ns) +{ + dec_ucount(ns, UCOUNT_CGROUP_NAMESPACES); +} + static struct cgroup_namespace *alloc_cgroup_ns(void) { struct cgroup_namespace *new_ns; @@ -6281,6 +6291,7 @@ static struct cgroup_namespace *alloc_cgroup_ns(void) void free_cgroup_ns(struct cgroup_namespace *ns) { put_css_set(ns->root_cset); + dec_cgroup_namespaces(ns->user_ns); put_user_ns(ns->user_ns); ns_free_inum(&ns->ns); kfree(ns); @@ -6305,6 +6316,9 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, if (!ns_capable(user_ns, CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); + if (!inc_cgroup_namespaces(user_ns)) + return ERR_PTR(-ENFILE); + mutex_lock(&cgroup_mutex); spin_lock_bh(&css_set_lock); @@ -6317,6 +6331,7 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, new_ns = alloc_cgroup_ns(); if (IS_ERR(new_ns)) { put_css_set(cset); + dec_cgroup_namespaces(user_ns); return new_ns; } diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 8c3a6e351b3e..c150765c328e 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -80,6 +80,7 @@ static struct ctl_table userns_table[] = { UCOUNT_ENTRY("max_pid_namespaces"), UCOUNT_ENTRY("max_uts_namespaces"), UCOUNT_ENTRY("max_ipc_namespaces"), + UCOUNT_ENTRY("max_cgroup_namespaces"), { } }; #endif /* CONFIG_SYSCTL */ -- 2.8.3