From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen Gang Subject: Re: [PATCH] ipv4: netfilter: always let NUL terminated string ended by '\0' Date: Thu, 23 May 2013 19:59:19 +0800 Message-ID: <519E0497.5000002@asianux.com> References: <5195ECB3.5000006@asianux.com> <20130523110832.GB22553@localhost> <519DFFFB.40104@asianux.com> <20130523114950.GA4972@localhost> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130523114950.GA4972@localhost> Sender: netfilter-devel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Pablo Neira Ayuso Cc: kaber@trash.net, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, David Miller , netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org, coreteam@netfilter.org, netdev On 05/23/2013 07:49 PM, Pablo Neira Ayuso wrote: > On Thu, May 23, 2013 at 07:39:39PM +0800, Chen Gang wrote: >> > On 05/23/2013 07:08 PM, Pablo Neira Ayuso wrote: >>> > > On Fri, May 17, 2013 at 04:39:15PM +0800, Chen Gang wrote: >>>>> > >> > >>>>> > >> > For NUL terminated string, better always be sure of ended by '\0'. >>>>> > >> > >>>>> > >> > 'pm' is 'struct ulog_packet_msg_t' which may be copied to user mode >>>>> > >> > (defined in "include/uapi/..."), so can not use strlcpy() instead of. >>> > > loginfo->prefix is always nul-terminated, as this is validated in >>> > > checkentry. I don't think the kernel will take a non nul-terminated >>> > > device name either. >> > >> > Really it is. >> > >> > And 'prefix' max length is 128 (NF_LOG_PREFIXLEN), and 'pm->prefix' max >> > length is 32 (ULOG_PREFIX_LEN), so we still need this patch, but need >> > improved. > Both are ULOG_PREFIX_LEN long. > >>>From include/uapi/linux/netfilter_ipv4/ipt_ULOG.h: > > /* private data structure for each rule with a ULOG target */ > struct ipt_ulog_info { > unsigned int nl_group; > size_t copy_range; > size_t qthreshold; > char prefix[ULOG_PREFIX_LEN]; > }; > > /* Format of the ULOG packets passed through netlink */ > typedef struct ulog_packet_msg { > unsigned long mark; > long timestamp_sec; > long timestamp_usec; > unsigned int hook; > char indev_name[IFNAMSIZ]; > char outdev_name[IFNAMSIZ]; > size_t data_len; > char prefix[ULOG_PREFIX_LEN]; > unsigned char mac_len; > unsigned char mac[ULOG_MAC_LEN; > unsigned char payload[0]; > } ulog_packet_msg_t; > > Yes, for 'loginfo->prefix', really it is. But for 'prefix', it is 128. the call work flow is: nf_log_packet() -> "char prefix[NF_LOG_PREFIXLEN];" logger->logfn() -> "prefix as last parameter" ipt_logfn() -> "prefix as last parameter" ipt_ulog_packet() "prefix as last parameter" netfilter/nf_log.c:16:#define NF_LOG_PREFIXLEN 128 Thanks. -- Chen Gang Asianux Corporation