Hi Florian,

El 19 de agosto de 2019 13:55:27 CEST, Florian Westphal <f...@strlen.de> 
escribió:
>Fernando Fernandez Mancera <ffmanc...@riseup.net> wrote:
>> This is a WIP patch version. I still having some issues in userspace
>but I
>> would like to get feedback about the kernel-side patch. Thanks!
>> 
>> Signed-off-by: Fernando Fernandez Mancera <ffmanc...@riseup.net>
>> ---
>>  include/net/netfilter/nf_tables.h |  6 +++
>>  net/netfilter/nf_tables_api.c     | 73
>++++++++++++++++++++++++++++---
>>  2 files changed, 72 insertions(+), 7 deletions(-)
>> 
>> diff --git a/include/net/netfilter/nf_tables.h
>b/include/net/netfilter/nf_tables.h
>> index dc301e3d6739..dc4e32040ea9 100644
>> --- a/include/net/netfilter/nf_tables.h
>> +++ b/include/net/netfilter/nf_tables.h
>> @@ -1123,6 +1123,9 @@ struct nft_object_ops {
>>      int                             (*dump)(struct sk_buff *skb,
>>                                              struct nft_object *obj,
>>                                              bool reset);
>> +    int                             (*update)(const struct nft_ctx *ctx,
>> +                                              const struct nlattr *const 
>> tb[],
>> +                                              struct nft_object *obj);
>>      const struct nft_object_type    *type;
>>  };
>>  
>> @@ -1405,10 +1408,13 @@ struct nft_trans_elem {
>>  
>>  struct nft_trans_obj {
>>      struct nft_object               *obj;
>> +    bool                            update;
>>  };
>>  
>>  #define nft_trans_obj(trans)        \
>>      (((struct nft_trans_obj *)trans->data)->obj)
>> +#define nft_trans_obj_update(trans) \
>> +    (((struct nft_trans_obj *)trans->data)->update)
>>  
>>  struct nft_trans_flowtable {
>>      struct nft_flowtable            *flowtable;
>> diff --git a/net/netfilter/nf_tables_api.c
>b/net/netfilter/nf_tables_api.c
>> index fe3b7b0c6c66..d7b94904599c 100644
>> --- a/net/netfilter/nf_tables_api.c
>> +++ b/net/netfilter/nf_tables_api.c
>> @@ -5122,6 +5122,48 @@ nft_obj_type_get(struct net *net, u32 objtype)
>>      return ERR_PTR(-ENOENT);
>>  }
>>  
>> +static int nf_tables_updobj(const struct nft_ctx *ctx,
>> +                        const struct nft_object_type *type,
>> +                        const struct nlattr *attr,
>> +                        struct nft_object *obj)
>> +{
>> +    struct nft_trans *trans;
>> +    struct nlattr **tb;
>> +    int err = -ENOMEM;
>> +
>> +    trans = nft_trans_alloc(ctx, NFT_MSG_NEWOBJ,
>> +                            sizeof(struct nft_trans_obj));
>> +    if (!trans)
>> +            return -ENOMEM;
>> +
>> +    tb = kmalloc_array(type->maxattr + 1, sizeof(*tb), GFP_KERNEL);
>
>You can use kcalloc here and then remove the memset().
>p
>> +    err = obj->ops->update(ctx, (const struct nlattr * const *)tb,
>obj);
>> +    if (err < 0)
>> +            goto err;
>
>This looks wrong, see below.
>
>> @@ -5161,7 +5203,13 @@ static int nf_tables_newobj(struct net *net,
>struct sock *nlsk,
>>                      NL_SET_BAD_ATTR(extack, nla[NFTA_OBJ_NAME]);
>>                      return -EEXIST;
>>              }
>> -            return 0;
>> +            if (nlh->nlmsg_flags & NLM_F_REPLACE)
>> +                    return -EOPNOTSUPP;
>> +
>> +            type = nft_obj_type_get(net, objtype);
>> +            nft_ctx_init(&ctx, net, skb, nlh, family, table, NULL, nla);
>> +
>> +            return nf_tables_updobj(&ctx, type, nla[NFTA_OBJ_DATA], obj);
>>      }
>>  
>>              case NFT_MSG_NEWOBJ:
>> -                    nft_clear(net, nft_trans_obj(trans));
>> -                    nf_tables_obj_notify(&trans->ctx, nft_trans_obj(trans),
>> -                                         NFT_MSG_NEWOBJ);
>> -                    nft_trans_destroy(trans);
>> +                    if (nft_trans_obj_update(trans)) {
>> +                            nf_tables_obj_notify(&trans->ctx,
>> +                                                 nft_trans_obj(trans),
>> +                                                 NFT_MSG_NEWOBJ);
>
>I would have expected the ->update() here, when committing the batch.
>Under what conditions can an update() fail?

It depends on the object type. In the quota case it can fail if the quota have 
invalid values.

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