On Mon, Feb 06, 2023 at 12:46:10PM +0100, Ales Musil wrote:
> The inner header was not handled properly.
> Simplify the code which allows proper handling
> of the inner headers.
> 
> Reported-at: https://bugzilla.redhat.com/2137754
> Signed-off-by: Ales Musil <[email protected]>

Nice clean-up too :)

Reviewed-by: Simon Horman <[email protected]>

> diff --git a/lib/conntrack.c b/lib/conntrack.c
> index 550b2be9b..3162924ca 100644
> --- a/lib/conntrack.c
> +++ b/lib/conntrack.c

...

>  static void
> -reverse_nat_packet(struct dp_packet *pkt, const struct conn *conn)
> +nat_inner_packet(struct dp_packet *pkt, struct conn_key *key,
> +                 uint16_t nat_action)
>  {
>      char *tail = dp_packet_tail(pkt);
>      uint16_t pad = dp_packet_l2_pad_size(pkt);
> @@ -875,98 +827,77 @@ reverse_nat_packet(struct dp_packet *pkt, const struct 
> conn *conn)
>      uint16_t orig_l3_ofs = pkt->l3_ofs;
>      uint16_t orig_l4_ofs = pkt->l4_ofs;
>  
> -    if (conn->key.dl_type == htons(ETH_TYPE_IP)) {
> -        struct ip_header *nh = dp_packet_l3(pkt);
> -        struct icmp_header *icmp = dp_packet_l4(pkt);
> -        struct ip_header *inner_l3 = (struct ip_header *) (icmp + 1);
> -        /* This call is already verified to succeed during the code path from
> -         * 'conn_key_extract()' which calls 'extract_l4_icmp()'. */
> -        extract_l3_ipv4(&inner_key, inner_l3, tail - ((char *)inner_l3) - 
> pad,
> +    void *l3 = dp_packet_l3(pkt);
> +    void *l4 = dp_packet_l4(pkt);
> +    void *inner_l3;
> +    /* These calls are already verified to succeed during the code path from
> +     * 'conn_key_extract()' which calls
> +     * 'extract_l4_icmp()'/'extract_l4_icmp6()'. */
> +    if (key->dl_type == htons(ETH_TYPE_IP)) {
> +        inner_l3 = (char *) l4 + sizeof(struct icmp_header);
> +        extract_l3_ipv4(&inner_key, inner_l3, tail - ((char *) inner_l3) - 
> pad,
>                          &inner_l4, false);
> -        pkt->l3_ofs += (char *) inner_l3 - (char *) nh;
> -        pkt->l4_ofs += inner_l4 - (char *) icmp;
> +    } else {
> +        inner_l3 = (char *) l4 + sizeof(struct icmp6_data_header);
> +        extract_l3_ipv6(&inner_key, inner_l3, tail - ((char *) inner_l3) - 
> pad,
> +                        &inner_l4);
> +    }
> +    pkt->l3_ofs += (char *) inner_l3 - (char *) l3;
> +    pkt->l4_ofs += inner_l4 - (char *) l4;
>  
> -        if (conn->nat_action & NAT_ACTION_SRC) {
> -            packet_set_ipv4_addr(pkt, &inner_l3->ip_src,
> -                                 conn->key.src.addr.ipv4);
> -        } else if (conn->nat_action & NAT_ACTION_DST) {
> -            packet_set_ipv4_addr(pkt, &inner_l3->ip_dst,
> -                                 conn->key.dst.addr.ipv4);
> -        }
> +    /* Reverse the key for inner packet. */
> +    struct conn_key rev_key = *key;
> +    conn_key_reverse(&rev_key);
> +
> +    pat_packet(pkt, &rev_key);
> +
> +    if (key->dl_type == htons(ETH_TYPE_IP)) {
> +        nat_packet_ipv4(pkt, &rev_key, nat_action);
>  
> -        reverse_pat_packet(pkt, conn);
> +        struct icmp_header *icmp = (struct icmp_header *) l4;
>          icmp->icmp_csum = 0;

nit: not for this patch, but is the above line necessary?

>          icmp->icmp_csum = csum(icmp, tail - (char *) icmp - pad);
>      } else {
> -        struct ovs_16aligned_ip6_hdr *nh6 = dp_packet_l3(pkt);
> -        struct icmp6_data_header *icmp6 = dp_packet_l4(pkt);
> -        struct ovs_16aligned_ip6_hdr *inner_l3_6 =
> -            (struct ovs_16aligned_ip6_hdr *) (icmp6 + 1);
> -        /* This call is already verified to succeed during the code path from
> -         * 'conn_key_extract()' which calls 'extract_l4_icmp6()'. */
> -        extract_l3_ipv6(&inner_key, inner_l3_6,
> -                        tail - ((char *)inner_l3_6) - pad,
> -                        &inner_l4);
> -        pkt->l3_ofs += (char *) inner_l3_6 - (char *) nh6;
> -        pkt->l4_ofs += inner_l4 - (char *) icmp6;
> -
> -        if (conn->nat_action & NAT_ACTION_SRC) {
> -            packet_set_ipv6_addr(pkt, conn->key.nw_proto,
> -                                 inner_l3_6->ip6_src.be32,
> -                                 &conn->key.src.addr.ipv6, true);
> -        } else if (conn->nat_action & NAT_ACTION_DST) {
> -            packet_set_ipv6_addr(pkt, conn->key.nw_proto,
> -                                 inner_l3_6->ip6_dst.be32,
> -                                 &conn->key.dst.addr.ipv6, true);
> -        }
> -        reverse_pat_packet(pkt, conn);
> +        nat_packet_ipv6(pkt, &rev_key, nat_action);
> +
> +        struct icmp6_data_header *icmp6 = (struct icmp6_data_header *) l4;
>          icmp6->icmp6_base.icmp6_cksum = 0;

ditto.

> -        icmp6->icmp6_base.icmp6_cksum = packet_csum_upperlayer6(nh6, icmp6,
> -            IPPROTO_ICMPV6, tail - (char *) icmp6 - pad);
> +        icmp6->icmp6_base.icmp6_cksum =
> +            packet_csum_upperlayer6(l3, icmp6, IPPROTO_ICMPV6,
> +                                    tail - (char *) icmp6 - pad);
>      }
> +
>      pkt->l3_ofs = orig_l3_ofs;
>      pkt->l4_ofs = orig_l4_ofs;
>  }
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