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Date: Thu, 4 Nov 2021 11:07:13 +0200
From: Vlad Buslov <vladbu@...dia.com>
To: Baowen Zheng <baowen.zheng@...igine.com>
CC: Simon Horman <simon.horman@...igine.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Jamal Hadi Salim <jhs@...atatu.com>,
Roi Dayan <roid@...dia.com>, Ido Schimmel <idosch@...dia.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>,
Baowen Zheng <notifications@...hub.com>,
Louis Peens <louis.peens@...igine.com>,
oss-drivers <oss-drivers@...igine.com>
Subject: Re: [RFC/PATCH net-next v3 8/8] flow_offload: validate flags of
filter and actions
On Thu 04 Nov 2021 at 07:51, Baowen Zheng <baowen.zheng@...igine.com> wrote:
> Sorry for reply this message again.
> On November 4, 2021 10:31 AM, Baowen Zheng wrote:
>>Thanks for your review and sorry for delay in responding.
>>On October 30, 2021 2:01 AM, Vlad Buslov wrote:
>>>On Thu 28 Oct 2021 at 14:06, Simon Horman <simon.horman@...igine.com>
>>>wrote:
>>>> From: Baowen Zheng <baowen.zheng@...igine.com>
>>>>
>>>> Add process to validate flags of filter and actions when adding a tc
>>>> filter.
>>>>
>>>> We need to prevent adding filter with flags conflicts with its actions.
>>>>
>>>> Signed-off-by: Baowen Zheng <baowen.zheng@...igine.com>
>>>> Signed-off-by: Louis Peens <louis.peens@...igine.com>
>>>> Signed-off-by: Simon Horman <simon.horman@...igine.com>
>>>> ---
>>>> net/sched/cls_api.c | 26 ++++++++++++++++++++++++++
>>>> net/sched/cls_flower.c | 3 ++-
>>>> net/sched/cls_matchall.c | 4 ++--
>>>> net/sched/cls_u32.c | 7 ++++---
>>>> 4 files changed, 34 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index
>>>> 351d93988b8b..80647da9713a 100644
>>>> --- a/net/sched/cls_api.c
>>>> +++ b/net/sched/cls_api.c
>>>> @@ -3025,6 +3025,29 @@ void tcf_exts_destroy(struct tcf_exts *exts)
>>>> } EXPORT_SYMBOL(tcf_exts_destroy);
>>>>
>>>> +static bool tcf_exts_validate_actions(const struct tcf_exts *exts,
>>>> +u32 flags) { #ifdef CONFIG_NET_CLS_ACT
>>>> + bool skip_sw = tc_skip_sw(flags);
>>>> + bool skip_hw = tc_skip_hw(flags);
>>>> + int i;
>>>> +
>>>> + if (!(skip_sw | skip_hw))
>>>> + return true;
>>>> +
>>>> + for (i = 0; i < exts->nr_actions; i++) {
>>>> + struct tc_action *a = exts->actions[i];
>>>> +
>>>> + if ((skip_sw && tc_act_skip_hw(a->tcfa_flags)) ||
>>>> + (skip_hw && tc_act_skip_sw(a->tcfa_flags)))
>>>> + return false;
>>>> + }
>>>> + return true;
>>>> +#else
>>>> + return true;
>>>> +#endif
>>>> +}
>>>> +
>>>
>>>I know Jamal suggested to have skip_sw for actions, but it complicates
>>>the code and I'm still not entirely understand why it is necessary.
>>>After all, action can only get applied to a packet if the packet has
>>>been matched by some filter and filters already have skip sw/hw
>>>controls. Forgoing action skip_sw flag would:
>>>
>>>- Alleviate the need to validate that filter and action flags are compatible.
>>>(trying to offload filter that points to existing skip_hw action would
>>>just fail because the driver wouldn't find the action with provided id
>>>in its tables)
>>>
>>>- Remove the need to add more conditionals into TC software data path
>>>in patch 4.
>>>
>>>WDYT?
>>As we discussed with Jamal, we will keep the flag of skip_sw and we need to
>>make exactly match for the actions with flags and the filter specific action with
>>index.
>>>
>>>> int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr
>>**tb,
>>>> struct nlattr *rate_tlv, struct tcf_exts *exts,
>>>> u32 flags, struct netlink_ext_ack *extack) @@ -3066,6
>>>+3089,9
>>>> @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp,
>>>> struct nlattr
>>>**tb,
>>>> return err;
>>>> exts->nr_actions = err;
>>>> }
>>>> +
>>>> + if (!tcf_exts_validate_actions(exts, flags))
>>>> + return -EINVAL;
>>>> }
>>>> #else
>>>> if ((exts->action && tb[exts->action]) || diff --git
>>>> a/net/sched/cls_flower.c b/net/sched/cls_flower.c index
>>>> eb6345a027e1..55f89f0e393e 100644
>>>> --- a/net/sched/cls_flower.c
>>>> +++ b/net/sched/cls_flower.c
>>>> @@ -2035,7 +2035,8 @@ static int fl_change(struct net *net, struct
>>>> sk_buff
>>>*in_skb,
>>>> }
>>>>
>>>> err = fl_set_parms(net, tp, fnew, mask, base, tb, tca[TCA_RATE],
>>>> - tp->chain->tmplt_priv, flags, extack);
>>>> + tp->chain->tmplt_priv, flags | fnew->flags,
>>>> + extack);
>>>
>>>Aren't you or-ing flags from two different ranges (TCA_CLS_FLAGS_* and
>>>TCA_ACT_FLAGS_*) that map to same bits, or am I missing something? This
>>>isn't explained in commit message so it is hard for me to understand
>>>the idea here.
>>Yes, as you said we use TCA_CLS_FLAGS_* or TCA_ACT_FLAGS_* flags to
>>validate the action flags.
>>As you know, the TCA_ACT_FLAGS_* in flags are system flags(in high 16 bits)
>>and the TCA_CLS_FLAGS_* are user flags(in low 16 bits), so they will not be
>>conflict.
Indeed, currently available TCA_CLS_FLAGS_* fit into first 16 bits, but
the field itself is 32 bits and with addition of more flags in the
future higher bits may start to be used since TCA_CLS_FLAGS_* and
TCA_ACT_FLAGS_* are independent sets.
>>But I think you suggestion also makes sense to us, do you think we need to
>>pass a single filter flag to make the process more clear?
> After consideration, I think it is better to separate CLS flags and ACT flags.
> So we will pass CLS flags as a separate flags, thanks.
Please also validate inside tcf_action_init() instead of creating new
tcf_exts_validate_actions() function, if possible. I think this will
lead to cleaner and more simple code.
>>>
>>>> if (err)
>>>> goto errout;
>>>>
>>>> diff --git a/net/sched/cls_matchall.c b/net/sched/cls_matchall.c
>>>> index 24f0046ce0b3..00b76fbc1dce 100644
>>>> --- a/net/sched/cls_matchall.c
>>>> +++ b/net/sched/cls_matchall.c
>>>> @@ -226,8 +226,8 @@ static int mall_change(struct net *net, struct
>>>> sk_buff
>>>*in_skb,
>>>> goto err_alloc_percpu;
>>>> }
>>>>
>>>> - err = mall_set_parms(net, tp, new, base, tb, tca[TCA_RATE], flags,
>>>> - extack);
>>>> + err = mall_set_parms(net, tp, new, base, tb, tca[TCA_RATE],
>>>> + flags | new->flags, extack);
>>>> if (err)
>>>> goto err_set_parms;
>>>>
>>>> diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index
>>>> 4272814487f0..fc670cc45122 100644
>>>> --- a/net/sched/cls_u32.c
>>>> +++ b/net/sched/cls_u32.c
>>>> @@ -895,7 +895,8 @@ static int u32_change(struct net *net, struct
>>>> sk_buff
>>>*in_skb,
>>>> return -ENOMEM;
>>>>
>>>> err = u32_set_parms(net, tp, base, new, tb,
>>>> - tca[TCA_RATE], flags, extack);
>>>> + tca[TCA_RATE], flags | new->flags,
>>>> + extack);
>>>>
>>>> if (err) {
>>>> u32_destroy_key(new, false);
>>>> @@ -1060,8 +1061,8 @@ static int u32_change(struct net *net, struct
>>>sk_buff *in_skb,
>>>> }
>>>> #endif
>>>>
>>>> - err = u32_set_parms(net, tp, base, n, tb, tca[TCA_RATE], flags,
>>>> - extack);
>>>> + err = u32_set_parms(net, tp, base, n, tb, tca[TCA_RATE],
>>>> + flags | n->flags, extack);
>>>> if (err == 0) {
>>>> struct tc_u_knode __rcu **ins;
>>>> struct tc_u_knode *pins;
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