[dpdk-dev] ACL: BUG: rte_acl_classify_scalar mismatch when use a special rule

[Ananyev, Konstantin]

Hi,

> 
> define a rule as following:
> 
> struct acl_ipv4_rule acl_rule[] = {
> {
>         .data = {.userdata = 103, .category_mask = 1, .priority = 1},
>         /* proto */
>         .field[0] = {.value.u8 = 0, .mask_range.u8 = 0x0,},
>         /* source IPv4 */
>         .field[1] = {.value.u32 = IPv4(0, 0, 0, 0), .mask_range.u32 = 0,},
>         /* destination IPv4 */
>         .field[2] = {.value.u32 = IPv4(192, 168, 2, 4), .mask_range.u32 = 32,},
>         /* source port */
>         .field[3] = {.value.u16 = 0, .mask_range.u16 = 0xffff,},
>         /* destination port */
>         .field[4] = {.value.u16 = 1024, .mask_range.u16 = 0xffff,},
>     },
> };
> 
> build a pkt like this:
> 
> pv4_hdr->next_proto_id = 6;
> ipv4_hdr->src_addr = rte_cpu_to_be_32(IPv4(10, 18, 2, 3));
> ipv4_hdr->dst_addr = rte_cpu_to_be_32(IPv4(192, 168, 2, 4));
> port = (uint16_t*)((unsigned char*)ipv4_hdr + sizeof(struct ipv4_hdr));
> port[0] = rte_cpu_to_be_16(3333);
> port[1] = rte_cpu_to_be_16(4608);
> 
> rte_acl_classify_scalar will mismatch this packet!
> 
> i readed rte_acl_classify_scalar function, and found the reason:
> 
>     while (flows.started > 0) {
> 
>         input0 = GET_NEXT_4BYTES(parms, 0);
>         input1 = GET_NEXT_4BYTES(parms, 1);
> 
>         for (n = 0; n < 4; n++) {
> 
>             transition0 = scalar_transition(flows.trans,
>                 transition0, (uint8_t)input0);
>             input0 >>= CHAR_BIT;
> 
>             transition1 = scalar_transition(flows.trans,
>                 transition1, (uint8_t)input1);
>             input1 >>= CHAR_BIT;
>         }
> 
>         while ((transition0 | transition1) & RTE_ACL_NODE_MATCH) {
>             transition0 = acl_match_check(transition0,
>                 0, ctx, parms, &flows, resolve_priority_scalar);
>             transition1 = acl_match_check(transition1,
>                 1, ctx, parms, &flows, resolve_priority_scalar);
>         }
>     }
> 
> everytime, scalar get 4bytes to transition, and usually it work well, but if we set a acl rule as prior, mismatch will appear.
> this is because field[3] is a 100% wild node, so it was removed as a deactivated field.
> 
> in this situation, when rte_acl_classify_scalar runs, proto/sip/dip match ok, and then it skip sport because it was removed.
> now input0 is a int value(4 bytes) started form dport.
> it will get a match-node after 2 bytes match(dport is a short value), but cycle stoped untill n = 4, finally it translated to another node which is
> not a match-node, the mismatch happened.
> 
> i'm not sure search_sse_8/search_sse_4/search_avx2x16 is Ok.
> 
> how to fix it?
> i think set GET_NEXT_4BYTES to GET_NEXT_BYTE will solve this problem, but it will influence performance.
> another way, don't use acl_rule_stats to remove deactivated field, but code will change a lot.

If you believe there is a problem, could you try to reproduce it with app/testacl,
and provide a rule file and a trace file?
Thanks
Konstantin