netdev - Re: [PATCH v3 09/12] l2tp: Add netlink control API for L2TP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4BB30F03.7090806@trash.net>
Date:	Wed, 31 Mar 2010 10:59:47 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	James Chapman <jchapman@...alix.com>
CC:	netdev@...r.kernel.org
Subject: Re: [PATCH v3 09/12] l2tp: Add netlink control API for L2TP

James Chapman wrote:
> +static struct nla_policy l2tp_nl_policy[L2TP_ATTR_MAX + 1] = {
> +	[L2TP_ATTR_NONE]		= { .type = NLA_UNSPEC, },
> +	[L2TP_ATTR_PW_TYPE]		= { .type = NLA_U16, },
> +	[L2TP_ATTR_ENCAP_TYPE]		= { .type = NLA_U16, },
> +	[L2TP_ATTR_OFFSET]		= { .type = NLA_U16, },
> +	[L2TP_ATTR_DATA_SEQ]		= { .type = NLA_U8, },
> +	[L2TP_ATTR_L2SPEC_TYPE]		= { .type = NLA_U8, },
> +	[L2TP_ATTR_L2SPEC_LEN]		= { .type = NLA_U8, },
> +	[L2TP_ATTR_PROTO_VERSION]	= { .type = NLA_U8, },
> +	[L2TP_ATTR_CONN_ID]		= { .type = NLA_U32, },
> +	[L2TP_ATTR_PEER_CONN_ID]	= { .type = NLA_U32, },
> +	[L2TP_ATTR_SESSION_ID]		= { .type = NLA_U32, },
> +	[L2TP_ATTR_PEER_SESSION_ID]	= { .type = NLA_U32, },
> +	[L2TP_ATTR_UDP_CSUM]		= { .type = NLA_FLAG, },
> +	[L2TP_ATTR_VLAN_ID]		= { .type = NLA_U16, },
> +	[L2TP_ATTR_DEBUG]		= { .type = NLA_U32, },
> +	[L2TP_ATTR_RECV_SEQ]		= { .type = NLA_FLAG, },
> +	[L2TP_ATTR_SEND_SEQ]		= { .type = NLA_FLAG, },
> +	[L2TP_ATTR_LNS_MODE]		= { .type = NLA_FLAG, },
> +	[L2TP_ATTR_USING_IPSEC]		= { .type = NLA_FLAG, },

Please don't use NLA_FLAG, it diverges from the usual netlink
attribute semantics since you either can't unset the flag in
case you check for the presence of the attribute (the attribute
can only encode "flag set") or you'll have to send the current
value in every message even if you don't intend to change it.
In this case it can't be unset.

A better way is to use something like this:

struct l2tp_flags {
	__u32	value;
	__u32	mask;
};

and set mask to the bits you intend to change.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html