Re: [Qemu-devel] [PATCH 1/3] COLO-compare: Add minimum packet size check and some fix

[Zhang Chen <zhangchen.fnst@cn.fujitsu.com>]

On 02/25/2017 02:43 PM, Hailiang Zhang wrote:
> Hi,
>
> On 2017/2/25 11:32, Zhang Chen wrote:
>> Add packet minimum size check in colo_packet_compare_udp()
>> and colo_packet_compare_udp() like colo_packet_compare_icmp(),
>> rename function colo_packet_compare() to colo_packet_compare_common()
>> that we will reuse it later.
>>
>> Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
>> ---
>>   net/colo-compare.c | 30 ++++++++++++++++++++++--------
>>   1 file changed, 22 insertions(+), 8 deletions(-)
>>
>> diff --git a/net/colo-compare.c b/net/colo-compare.c
>> index 300f017..e75f0ae 100644
>> --- a/net/colo-compare.c
>> +++ b/net/colo-compare.c
>> @@ -180,7 +180,7 @@ static int packet_enqueue(CompareState *s, int mode)
>>    * return:    0  means packet same
>>    *            > 0 || < 0 means packet different
>>    */
>> -static int colo_packet_compare(Packet *ppkt, Packet *spkt)
>> +static int colo_packet_compare_common(Packet *ppkt, Packet *spkt)
>>   {
>>       trace_colo_compare_ip_info(ppkt->size, 
>> inet_ntoa(ppkt->ip->ip_src),
>> inet_ntoa(ppkt->ip->ip_dst), spkt->size,
>> @@ -190,6 +190,7 @@ static int colo_packet_compare(Packet *ppkt, 
>> Packet *spkt)
>>       if (ppkt->size == spkt->size) {
>>           return memcmp(ppkt->data, spkt->data, spkt->size);
>>       } else {
>> +        trace_colo_compare_main("Net packet size are not the same");
>>           return -1;
>>       }
>>   }
>> @@ -202,9 +203,10 @@ static int colo_packet_compare(Packet *ppkt, 
>> Packet *spkt)
>>   static int colo_packet_compare_tcp(Packet *spkt, Packet *ppkt)
>>   {
>>       struct tcphdr *ptcp, *stcp;
>> -    int res;
>> +    int res, network_length;
>>
>>       trace_colo_compare_main("compare tcp");
>> +
>>       if (ppkt->size != spkt->size) {
>>           if (trace_event_get_state(TRACE_COLO_COMPARE_MISCOMPARE)) {
>>               trace_colo_compare_main("pkt size not same");
>> @@ -212,6 +214,12 @@ static int colo_packet_compare_tcp(Packet *spkt, 
>> Packet *ppkt)
>>           return -1;
>>       }
>>
>> +    network_length = ppkt->ip->ip_hl * 4;
>> +    if (ppkt->size < network_length + ETH_HLEN) {
>
> I think the check here is useless, because you have such check in
> parse_packet_early() which is been called before these helpers.
> And what check you need to add is, to check if the packet's size
>> = packet's length been record in ip header.
>
> Like:
> +++ b/net/colo.c
> @@ -78,6 +78,12 @@ int parse_packet_early(Packet *pkt)
>          trace_colo_proxy_main("pkt->size < network_header + 
> network_length");
>          return 1;
>      }
> +
> +    if (pkt->size < ETH_HLEN + ntohs(pkt->ip->ip_len)) {
> +        fprintf(stderr, "pkt->size %d < pkt expect total len %ld\n", 
> pkt->size,
> +            pkt_MAChdr_len + ntohs(pkt->ip->ip_len));
> +        return -1;
> +    }

This check we also have done in parse_packet_early()

     network_length = pkt->ip->ip_hl * 4;
     if (pkt->size < l2hdr_len + network_length) {
         trace_colo_proxy_main("pkt->size < network_header + 
network_length");
         return 1;
     }

So, maybe I need remove my before change and the compare_icmp() check.

Thanks
Zhang Chen



>
>
>> +        trace_colo_compare_main("tcp packet size error");
>> +        return -1;
>> +    }
>> +
>>       ptcp = (struct tcphdr *)ppkt->transport_header;
>>       stcp = (struct tcphdr *)spkt->transport_header;
>>
>> @@ -260,10 +268,16 @@ static int colo_packet_compare_tcp(Packet 
>> *spkt, Packet *ppkt)
>>    */
>>   static int colo_packet_compare_udp(Packet *spkt, Packet *ppkt)
>>   {
>> -    int ret;
>> +    int ret, network_length;
>>
>>       trace_colo_compare_main("compare udp");
>> -    ret = colo_packet_compare(ppkt, spkt);
>> +    network_length = ppkt->ip->ip_hl * 4;
>> +    if (ppkt->size < network_length + ETH_HLEN) {
>> +        trace_colo_compare_main("udp packet size error");
>> +        return -1;
>> +    }
>> +
>> +    ret = colo_packet_compare_common(ppkt, spkt);
>>
>>       if (ret) {
>>           trace_colo_compare_udp_miscompare("primary pkt size", 
>> ppkt->size);
>> @@ -285,12 +299,12 @@ static int colo_packet_compare_icmp(Packet 
>> *spkt, Packet *ppkt)
>>
>>       trace_colo_compare_main("compare icmp");
>>       network_length = ppkt->ip->ip_hl * 4;
>> -    if (ppkt->size != spkt->size ||
>> -        ppkt->size < network_length + ETH_HLEN) {
>> +    if (ppkt->size < network_length + ETH_HLEN) {
>> +        trace_colo_compare_main("icmp packet size error");
>>           return -1;
>>       }
>>
>> -    if (colo_packet_compare(ppkt, spkt)) {
>> +    if (colo_packet_compare_common(ppkt, spkt)) {
>>           trace_colo_compare_icmp_miscompare("primary pkt size",
>>                                              ppkt->size);
>>           qemu_hexdump((char *)ppkt->data, stderr, "colo-compare",
>> @@ -316,7 +330,7 @@ static int colo_packet_compare_other(Packet 
>> *spkt, Packet *ppkt)
>> inet_ntoa(ppkt->ip->ip_dst), spkt->size,
>> inet_ntoa(spkt->ip->ip_src),
>> inet_ntoa(spkt->ip->ip_dst));
>> -    return colo_packet_compare(ppkt, spkt);
>> +    return colo_packet_compare_common(ppkt, spkt);
>>   }
>>
>>   static int colo_old_packet_check_one(Packet *pkt, int64_t *check_time)
>>
>
>
>
>
> .
>

-- 
Thanks
Zhang Chen