netdev - Re: [net-next PATCH v2 1/5] introduce IFE action

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Message-ID: <56CDEA6D.1000908@iogearbox.net>
Date:	Wed, 24 Feb 2016 18:37:49 +0100
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Jamal Hadi Salim <jhs@...atatu.com>, davem@...emloft.net
CC:	netdev@...r.kernel.org, xiyou.wangcong@...il.com,
	alexei.starovoitov@...il.com, john.fastabend@...il.com,
	dj@...izon.com
Subject: Re: [net-next PATCH v2 1/5] introduce IFE action

On 02/23/2016 01:49 PM, Jamal Hadi Salim wrote:
> From: Jamal Hadi Salim <jhs@...atatu.com>
[...]
> +static const struct nla_policy ife_policy[TCA_IFE_MAX + 1] = {
> +	[TCA_IFE_PARMS] = {.len = sizeof(struct tc_ife)},
> +	[TCA_IFE_DMAC] = {.type = NLA_BINARY,.len = ETH_ALEN},
> +	[TCA_IFE_SMAC] = {.type = NLA_BINARY,.len = ETH_ALEN},

This is buggy btw ...

> +	[TCA_IFE_TYPE] = {.type = NLA_U16},
> +};

[...]

> +	if (parm->flags & IFE_ENCODE) {
> +		ife_type = *(u16 *) nla_data(tb[TCA_IFE_TYPE]);

( We have accessors for such things. Please also check coding style
   and white space things in your series, there's couple of things all
   over the place. )

> +		if (tb[TCA_IFE_DMAC] != NULL)
> +			daddr = nla_data(tb[TCA_IFE_DMAC]);
> +		if (tb[TCA_IFE_SMAC] != NULL)
> +			saddr = nla_data(tb[TCA_IFE_SMAC]);

... NLA_BINARY with len means: max length. But there's nothing
that checks a min length on this, so you potentially access out
of bounds since everything <= ETH_ALEN is allowed in your case.

> +	}
> +
> +	spin_lock_bh(&ife->tcf_lock);

Maybe try to make this lockless in the fast path? Otherwise placing
this on ingress / egress (f.e. clsact) doesn't really scale.

> +	ife->tcf_action = parm->action;
> +
> +	if (parm->flags & IFE_ENCODE) {
> +		if (daddr)
> +			ether_addr_copy(ife->eth_dst, daddr);
> +		else
> +			eth_zero_addr(ife->eth_dst);
> +
> +		if (saddr)
> +			ether_addr_copy(ife->eth_src, saddr);
> +		else
> +			eth_zero_addr(ife->eth_src);
> +
> +		ife->eth_type = ife_type;
> +	}