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Message-Id: <20160721164014.17534-8-ebiederm@xmission.com> Date: Thu, 21 Jul 2016 11:40:12 -0500 From: "Eric W. Biederman" <ebiederm@...ssion.com> To: Linux Containers <containers@...ts.linux-foundation.org> Cc: Andy Lutomirski <luto@...capital.net>, Jann Horn <jann@...jh.net>, Kees Cook <keescook@...omium.org>, Nikolay Borisov <kernel@...p.com>, "Serge E. Hallyn" <serge@...lyn.com>, Seth Forshee <seth.forshee@...onical.com>, linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, linux-api@...r.kernel.org, "Eric W. Biederman" <ebiederm@...ssion.com> Subject: [PATCH v2 08/10] cgroupns: Add a limit on the number of cgroup namespaces Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com> --- 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 367cf08ff63d..1a3a9cb93277 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_COUNTS, }; 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 060d3e099f87..1cf074cb47e2 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
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