netdev - Re: [PATCH v2 net-next 23/23] rtnetlink: Update rtnl_fdb

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Date:   Mon, 8 Oct 2018 13:02:21 +0200
From:   Christian Brauner <christian@...uner.io>
To:     David Ahern <dsahern@...nel.org>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, jbenc@...hat.com,
        stephen@...workplumber.org, David Ahern <dsahern@...il.com>
Subject: Re: [PATCH v2 net-next 23/23] rtnetlink: Update rtnl_fdb_dump for
 strict data checking

On Sun, Oct 07, 2018 at 08:16:44PM -0700, David Ahern wrote:
> From: David Ahern <dsahern@...il.com>
> 
> Update rtnl_fdb_dump for strict data checking. If the flag is set,
> the dump request is expected to have an ndmsg struct as the header
> potentially followed by one or more attributes. Any data passed in the
> header or as an attribute is taken as a request to influence the data
> returned. Only values supported by the dump handler are allowed to be
> non-0 or set in the request. At the moment only the NDA_IFINDEX and
> NDA_MASTER attributes are supported.
> 
> Signed-off-by: David Ahern <dsahern@...il.com>

Acked-by: Christian Brauner <christian@...uner.io>

> ---
>  net/core/rtnetlink.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 60 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index c7509c789fb6..c894c4af8981 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -3799,6 +3799,60 @@ int ndo_dflt_fdb_dump(struct sk_buff *skb,
>  }
>  EXPORT_SYMBOL(ndo_dflt_fdb_dump);
>  
> +static int valid_fdb_dump_strict(const struct nlmsghdr *nlh,
> +				 int *br_idx, int *brport_idx,
> +				 struct netlink_ext_ack *extack)
> +{
> +	struct nlattr *tb[NDA_MAX + 1];
> +	struct ndmsg *ndm;
> +	int err, i;
> +
> +	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ndm))) {
> +		NL_SET_ERR_MSG(extack, "Invalid header for fdb dump request");
> +		return -EINVAL;
> +	}
> +
> +	ndm = nlmsg_data(nlh);
> +	if (ndm->ndm_pad1  || ndm->ndm_pad2  || ndm->ndm_state ||
> +	    ndm->ndm_flags || ndm->ndm_type) {
> +		NL_SET_ERR_MSG(extack, "Invalid values in header for fbd dump request");
> +		return -EINVAL;
> +	}
> +
> +	err = nlmsg_parse_strict(nlh, sizeof(struct ndmsg), tb, NDA_MAX,
> +				 NULL, extack);
> +	if (err < 0)
> +		return err;
> +
> +	*brport_idx = ndm->ndm_ifindex;
> +	for (i = 0; i <= NDA_MAX; ++i) {
> +		if (!tb[i])
> +			continue;
> +
> +		switch (i) {
> +		case NDA_IFINDEX:
> +			if (nla_len(tb[i]) != sizeof(u32)) {
> +				NL_SET_ERR_MSG(extack, "Invalid IFINDEX attribute in fdb dump request");
> +				return -EINVAL;
> +			}
> +			*brport_idx = nla_get_u32(tb[NDA_IFINDEX]);
> +			break;
> +		case NDA_MASTER:
> +			if (nla_len(tb[i]) != sizeof(u32)) {
> +				NL_SET_ERR_MSG(extack, "Invalid MASTER attribute in fdb dump request");
> +				return -EINVAL;
> +			}
> +			*br_idx = nla_get_u32(tb[NDA_MASTER]);
> +			break;
> +		default:
> +			NL_SET_ERR_MSG(extack, "Unsupported attribute in fdb dump request");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static int valid_fdb_dump_legacy(const struct nlmsghdr *nlh,
>  				 int *br_idx, int *brport_idx,
>  				 struct netlink_ext_ack *extack)
> @@ -3846,8 +3900,12 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
>  	int err = 0;
>  	int fidx = 0;
>  
> -	err = valid_fdb_dump_legacy(cb->nlh, &br_idx, &brport_idx,
> -				    cb->extack);
> +	if (cb->strict_check)
> +		err = valid_fdb_dump_strict(cb->nlh, &br_idx, &brport_idx,
> +					    cb->extack);
> +	else
> +		err = valid_fdb_dump_legacy(cb->nlh, &br_idx, &brport_idx,
> +					    cb->extack);
>  	if (err < 0)
>  		return err;
>  
> -- 
> 2.11.0
>