Daniel, thanks for your comments.
bpf_get_netns_cookie_sock really sounds better.
But I still have another question that is how can I get the netns cookie when I invoke the function “msg_redirect_hash" because its parameter "struct sk_msg_md” does not have any netns information, and there is no "struct sock * ctx” to be used for the helper function “bpf_get_netns_cookie_sock" too. Add a field for sk_msg_md ? And just like I did for bpf_sock_ops ?
> 在 2020年6月5日，下午11:22，Daniel Borkmann <daniel@xxxxxxxxxxxxx> 写道：
>
> On 6/5/20 4:53 PM, Jakub Sitnicki wrote:
>> On Fri, Jun 05, 2020 at 02:40 PM CEST, Wang Li wrote:
>>> Sometimes we need net namespace as part of the key for BPF_MAP_TYPE_SOCKHASH to
>>> distinguish the connections with same five-tuples, for example when we do the
>>> sock_map acceleration for the proxy that uses 127.0.0.1 to 127.0.0.1 connections
>>> in different containers on same node.
>>> And we export the netns inum instead of the real pointer of struct net to avoid
>>> the potential security issue.
>>>
>>> Signed-off-by: Wang Li <wangli09@xxxxxxxxxxxx>
>>> Signed-off-by: huangxuesen <huangxuesen@xxxxxxxxxxxx>
>>> Signed-off-by: yangxingwu <yangxingwu@xxxxxxxxxxxx>
>>> ---
>>> include/uapi/linux/bpf.h | 2 ++
>>> net/core/filter.c | 17 +++++++++++++++++
>>> tools/include/uapi/linux/bpf.h | 2 ++
>>> 3 files changed, 21 insertions(+)
>>>
>>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
>>> index c65b374a5090..0fe7e459f023 100644
>>> --- a/include/uapi/linux/bpf.h
>>> +++ b/include/uapi/linux/bpf.h
>>> @@ -3947,6 +3947,8 @@ struct bpf_sock_ops {
>>> * there is a full socket. If not, the
>>> * fields read as zero.
>>> */
>>> + __u32 netns_inum; /* The net namespace this sock belongs to */
>>> +
>> In uapi/linux/bpf.h we have a field `netns_ino` for storing net
>> namespace inode number in a couple structs (bpf_prog_info,
>> bpf_map_info). Would be nice to keep the naming constent.
>
> Adding in the middle will break programs. Also, currently we have the
> merge window open and as such bpf-next is closed. Check status here [0].
>
> Regarding above, we recently added bpf_get_netns_cookie() helper, have
> you tried to enable this one instead?
>
> [0] http://vger.kernel.org/~davem/net-next.html
>
>>> diff --git a/net/core/filter.c b/net/core/filter.c
>>> index d01a244b5087..bfe448ace25f 100644
>>> --- a/net/core/filter.c
>>> +++ b/net/core/filter.c
>>> @@ -8450,6 +8450,23 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type,
>>> is_fullsock));
>>> break;
>>>
>>> + case offsetof(struct bpf_sock_ops, netns_inum):
>>> +#ifdef CONFIG_NET_NS
>>> + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
>>> + struct bpf_sock_ops_kern, sk),
>>> + si->dst_reg, si->src_reg,
>>> + offsetof(struct bpf_sock_ops_kern, sk));
>>> + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
>>> + struct sock_common, skc_net),
>>> + si->dst_reg, si->dst_reg,
>>> + offsetof(struct sock_common, skc_net));
>>> + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
>>> + offsetof(struct net, ns.inum));
>>> +#else
>>> + *insn++ = BPF_MOV32_IMM(si->dst_reg, 0);
>>> +#endif
>>> + break;
>>> +
>>> case offsetof(struct bpf_sock_ops, state):
>>> BUILD_BUG_ON(sizeof_field(struct sock_common, skc_state) != 1);
>>>
>>> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
>>> index c65b374a5090..0fe7e459f023 100644
>>> --- a/tools/include/uapi/linux/bpf.h
>>> +++ b/tools/include/uapi/linux/bpf.h
>>> @@ -3947,6 +3947,8 @@ struct bpf_sock_ops {
>>> * there is a full socket. If not, the
>>> * fields read as zero.
>>> */
>>> + __u32 netns_inum; /* The net namespace this sock belongs to */
>>> +
>>> __u32 snd_cwnd;
>>> __u32 srtt_us; /* Averaged RTT << 3 in usecs */
>>> __u32 bpf_sock_ops_cb_flags; /* flags defined in uapi/linux/tcp.h */
>
