Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932611AbbKQTly (ORCPT ); Tue, 17 Nov 2015 14:41:54 -0500 Received: from mail-yk0-f182.google.com ([209.85.160.182]:34700 "EHLO mail-yk0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932462AbbKQTk5 (ORCPT ); Tue, 17 Nov 2015 14:40:57 -0500 From: Tejun Heo To: davem@davemloft.net, pablo@netfilter.org, kaber@trash.net, kadlec@blackhole.kfki.hu, lizefan@huawei.com, hannes@cmpxchg.org Cc: netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, daniel@iogearbox.net, daniel.wagner@bmw-carit.de, nhorman@tuxdriver.com, Tejun Heo Subject: [PATCH 4/5] sock, cgroup: add sock->sk_cgroup Date: Tue, 17 Nov 2015 14:40:39 -0500 Message-Id: <1447789240-29394-5-git-send-email-tj@kernel.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1447789240-29394-1-git-send-email-tj@kernel.org> References: <1447789240-29394-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6244 Lines: 181 In cgroup v1, dealing with cgroup membership was difficult because the number of membership associations was unbound. As a result, cgroup v1 grew several controllers whose primary purpose is either tagging membership or pull in configuration knobs from other subsystems so that cgroup membership test can be avoided. net_cls and net_prio controllers are examples of the latter. They allow configuring network-specific attributes from cgroup side so that network subsystem can avoid testing cgroup membership; unfortunately, these are not only cumbersome but also problematic. Both net_cls and net_prio aren't properly hierarchical. Both inherit configuration from the parent on creation but there's no interaction afterwards. An ancestor doesn't restrict the behavior in its subtree in anyway and configuration changes aren't propagated downwards. Especially when combined with cgroup delegation, this is problematic because delegatees can mess up whatever network configuration implemented at the system level. net_prio would allow the delegatees to set whatever priority value regardless of CAP_NET_ADMIN and net_cls the same for classid. While it is possible to solve these issues from controller side by implementing hierarchical allowable ranges in both controllers, it would involve quite a bit of complexity in the controllers and further obfuscate network configuration as it becomes even more difficult to tell what's actually being configured looking from the network side. While not much can be done for v1 at this point, as membership handling is sane on cgroup v2, it'd be better to make cgroup matching behave like other network matches and classifiers than introducing further complications. In preparation, this patch adds sock->sk_cgroup which points to the associated cgroup. A sock is associated on creation and stays associated to the same cgroup until freed; unfortunately, this ends up adding another cgroup field to struct sock on top of sk_cgrp_prioidx and sk_classid. I tried to think of a way to somehow overload the existing fields but couldn't come up with a reasonable one. For the longer term, the fields can be rearranged so that disabling prio and cls controllers reduce the size of the struct. This patch doesn't make use of the added field yet. The following patch will implement netfilter match for cgroup2 membership. Signed-off-by: Tejun Heo Cc: Daniel Borkmann Cc: Daniel Wagner CC: Neil Horman --- include/linux/cgroup.h | 8 ++++++++ include/net/sock.h | 4 ++++ kernel/cgroup.c | 25 ++++++++++++++++++++++++- net/core/sock.c | 2 ++ 4 files changed, 38 insertions(+), 1 deletion(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 4c3ffab..2a6d7c4 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -20,6 +20,8 @@ #include +struct sock; + #ifdef CONFIG_CGROUPS /* @@ -108,6 +110,9 @@ void cgroup_free(struct task_struct *p); int cgroup_init_early(void); int cgroup_init(void); +void cgroup_sk_alloc(struct sock *sk); +void cgroup_sk_free(struct sock *sk); + /* * Iteration helpers and macros. */ @@ -576,6 +581,9 @@ static inline void cgroup_free(struct task_struct *p) {} static inline int cgroup_init_early(void) { return 0; } static inline int cgroup_init(void) { return 0; } +static inline void cgroup_sk_alloc(struct sock *sk) {} +static inline void cgroup_sk_free(struct sock *sk) {} + #endif /* !CONFIG_CGROUPS */ #endif /* _LINUX_CGROUP_H */ diff --git a/include/net/sock.h b/include/net/sock.h index bbf7c2c..6c5d195 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -310,6 +310,7 @@ struct cg_proto; * @sk_security: used by security modules * @sk_mark: generic packet mark * @sk_classid: this socket's cgroup classid + * @sk_cgroup: the v2 cgroup this socket is associated with * @sk_cgrp: this socket's cgroup-specific proto data * @sk_write_pending: a write to stream socket waits to start * @sk_state_change: callback to indicate change in the state of the sock @@ -447,6 +448,9 @@ struct sock { #ifdef CONFIG_CGROUP_NET_CLASSID u32 sk_classid; #endif +#ifdef CONFIG_CGROUPS + struct cgroup *sk_cgroup; +#endif struct cg_proto *sk_cgrp; void (*sk_state_change)(struct sock *sk); void (*sk_data_ready)(struct sock *sk); diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 49947c1..f26533b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -57,8 +57,8 @@ #include /* TODO: replace with more sophisticated array */ #include #include - #include +#include /* * pidlists linger the following amount before being destroyed. The goal @@ -5781,6 +5781,29 @@ struct cgroup *cgroup_get_from_path(const char *path) return cgrp; } +void cgroup_sk_alloc(struct sock *sk) +{ + rcu_read_lock(); + + while (true) { + struct css_set *cset; + + cset = task_css_set(current); + if (likely(cgroup_tryget(cset->dfl_cgrp))) { + sk->sk_cgroup = cset->dfl_cgrp; + break; + } + cpu_relax(); + } + + rcu_read_unlock(); +} + +void cgroup_sk_free(struct sock *sk) +{ + cgroup_put(sk->sk_cgroup); +} + #ifdef CONFIG_CGROUP_DEBUG static struct cgroup_subsys_state * debug_css_alloc(struct cgroup_subsys_state *parent_css) diff --git a/net/core/sock.c b/net/core/sock.c index 1e4dd54..7c34bba 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1363,6 +1363,7 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority, if (!try_module_get(prot->owner)) goto out_free_sec; sk_tx_queue_clear(sk); + cgroup_sk_alloc(sk); } return sk; @@ -1385,6 +1386,7 @@ static void sk_prot_free(struct proto *prot, struct sock *sk) owner = prot->owner; slab = prot->slab; + cgroup_sk_free(sk); security_sk_free(sk); if (slab != NULL) kmem_cache_free(slab, sk); -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/