| Message ID | 5195ECB3.5000006@asianux.com |
|---|---|
| State | Superseded |
| Headers | show |
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. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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. So I should send patch v2. Thanks.
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; -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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.
diff --git a/net/ipv4/netfilter/ipt_ULOG.c b/net/ipv4/netfilter/ipt_ULOG.c index f8a222cb..4a93382 100644 --- a/net/ipv4/netfilter/ipt_ULOG.c +++ b/net/ipv4/netfilter/ipt_ULOG.c @@ -231,11 +231,13 @@ static void ipt_ulog_packet(unsigned int hooknum, put_unaligned(tv.tv_usec, &pm->timestamp_usec); put_unaligned(skb->mark, &pm->mark); pm->hook = hooknum; - if (prefix != NULL) - strncpy(pm->prefix, prefix, sizeof(pm->prefix)); - else if (loginfo->prefix[0] != '\0') - strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix)); - else + if (prefix != NULL) { + strncpy(pm->prefix, prefix, sizeof(pm->prefix) - 1); + pm->prefix[sizeof(pm->prefix) - 1] = '\0'; + } else if (loginfo->prefix[0] != '\0') { + strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix) - 1); + pm->prefix[sizeof(pm->prefix) - 1] = '\0'; + } else *(pm->prefix) = '\0'; if (in && in->hard_header_len > 0 && @@ -246,14 +248,17 @@ static void ipt_ulog_packet(unsigned int hooknum, } else pm->mac_len = 0; - if (in) - strncpy(pm->indev_name, in->name, sizeof(pm->indev_name)); - else + if (in) { + strncpy(pm->indev_name, in->name, sizeof(pm->indev_name) - 1); + pm->indev_name[sizeof(pm->indev_name) - 1] = '\0'; + } else pm->indev_name[0] = '\0'; - if (out) - strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name)); - else + if (out) { + strncpy(pm->outdev_name, out->name, + sizeof(pm->outdev_name) - 1); + pm->outdev_name[sizeof(pm->outdev_name) - 1] = '\0'; + } else pm->outdev_name[0] = '\0'; /* copy_len <= skb->len, so can't fail. */
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. Signed-off-by: Chen Gang <gang.chen@asianux.com> --- net/ipv4/netfilter/ipt_ULOG.c | 27 ++++++++++++++++----------- 1 files changed, 16 insertions(+), 11 deletions(-)