On Fri, 26 Apr 2024 at 11:27, Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
> On 4/23/24 8:00 PM, Brad Cowie wrote:
> > };
> >
> > static int bpf_nf_ct_tuple_parse(struct bpf_sock_tuple *bpf_tuple,
> > @@ -104,11 +107,13 @@ __bpf_nf_ct_alloc_entry(struct net *net, struct bpf_sock_tuple *bpf_tuple,
> > u32 timeout)
> > {
> > struct nf_conntrack_tuple otuple, rtuple;
> > + struct nf_conntrack_zone ct_zone;
> > struct nf_conn *ct;
> > int err;
> >
> > - if (!opts || !bpf_tuple || opts->reserved[0] || opts->reserved[1] ||
> > - opts_len != NF_BPF_CT_OPTS_SZ)
> > + if (!opts || !bpf_tuple)
> > + return ERR_PTR(-EINVAL);
> > + if (!(opts_len == NF_BPF_CT_OPTS_SZ || opts_len == NF_BPF_CT_OPTS_OLD_SZ))
> > return ERR_PTR(-EINVAL);
> >
> > if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS))
> > @@ -130,7 +135,16 @@ __bpf_nf_ct_alloc_entry(struct net *net, struct bpf_sock_tuple *bpf_tuple,
> > return ERR_PTR(-ENONET);
> > }
> >
> > - ct = nf_conntrack_alloc(net, &nf_ct_zone_dflt, &otuple, &rtuple,
> > + if (opts_len == NF_BPF_CT_OPTS_SZ) {
> > + if (opts->ct_zone_dir == 0)
>
> I don't know the details about the dir in ct_zone, so a question: a 0
> ct_zone_dir is invalid and can be reused to mean NF_CT_DEFAULT_ZONE_DIR?
ct_zone_dir is a bitmask that can have two different bits set,
NF_CT_ZONE_DIR_ORIG (1) and NF_CT_ZONE_DIR_REPL (2).
The comparison function nf_ct_zone_matches_dir() in nf_conntrack_zones.h
checks if ct_zone_dir & (1 << ip_conntrack_dir dir). ip_conntrack_dir
has two possible values IP_CT_DIR_ORIGINAL (0) and IP_CT_DIR_REPLY (1).
If ct_zone_dir has a value of 0, this makes nf_ct_zone_matches_dir()
always return false which makes nf_ct_zone_id() always return
NF_CT_DEFAULT_ZONE_ID instead of the specified ct zone id.
I chose to override ct_zone_dir here and set NF_CT_DEFAULT_ZONE_DIR (3),
to make the behaviour more obvious when a user calls the bpf ct helper
kfuncs while only setting ct_zone_id but not ct_zone_dir.
> > + opts->ct_zone_dir = NF_CT_DEFAULT_ZONE_DIR;
> > + nf_ct_zone_init(&ct_zone,
> > + opts->ct_zone_id, opts->ct_zone_dir, opts->ct_zone_flags);
> > + } else {
>
> Better enforce "ct_zone_id == 0" also instead of ignoring it.
Could I ask for clarification here, do you mean changing this
else statement to:
+ } else if (opts->ct_zone_id == 0) {
Or should I be setting opts->ct_zone_id = 0 inside the else block?
