On Mon, Oct 12, 2020 at 02:02:31PM +0200, Pablo Neira Ayuso wrote:
> On Wed, Sep 23, 2020 at 07:48:42PM +0200, Phil Sutter wrote:
> > This is a convenience function for adding a chain to cache, for now just
> > a simple wrapper around nftnl_chain_list_add_tail().
> >
> > Signed-off-by: Phil Sutter <phil@xxxxxx>
> > ---
> > Changes since v1:
> > - Use the function in nft_chain_builtin_add() as well.
> > ---
> > iptables/nft-cache.c | 12 +++++++++---
> > iptables/nft-cache.h | 3 +++
> > iptables/nft.c | 16 +++++++---------
> > 3 files changed, 19 insertions(+), 12 deletions(-)
> >
> > diff --git a/iptables/nft-cache.c b/iptables/nft-cache.c
> > index b94766a751db4..a22e693320451 100644
> > --- a/iptables/nft-cache.c
> > +++ b/iptables/nft-cache.c
> > @@ -165,6 +165,13 @@ static int fetch_table_cache(struct nft_handle *h)
> > return 1;
> > }
> >
> > +int nft_cache_add_chain(struct nft_handle *h, const struct builtin_table *t,
> > + struct nftnl_chain *c)
> > +{
> > + nftnl_chain_list_add_tail(c, h->cache->table[t->type].chains);
> > + return 0;
> > +}
>
> This wrapper LGTM.
>
> > struct nftnl_chain_list_cb_data {
> > struct nft_handle *h;
> > const struct builtin_table *t;
> > @@ -174,7 +181,6 @@ static int nftnl_chain_list_cb(const struct nlmsghdr *nlh, void *data)
> > {
> > struct nftnl_chain_list_cb_data *d = data;
> > const struct builtin_table *t = d->t;
> > - struct nftnl_chain_list *list;
> > struct nft_handle *h = d->h;
> > struct nftnl_chain *c;
> > const char *tname;
> > @@ -196,8 +202,8 @@ static int nftnl_chain_list_cb(const struct nlmsghdr *nlh, void *data)
> > goto out;
> > }
> >
> > - list = h->cache->table[t->type].chains;
> > - nftnl_chain_list_add_tail(c, list);
> > + if (nft_cache_add_chain(h, t, c))
> > + goto out;
> >
> > return MNL_CB_OK;
> > out:
> > diff --git a/iptables/nft-cache.h b/iptables/nft-cache.h
> > index 76f9fbb6c8ccc..d97f8de255f02 100644
> > --- a/iptables/nft-cache.h
> > +++ b/iptables/nft-cache.h
> > @@ -3,6 +3,7 @@
> >
> > struct nft_handle;
> > struct nft_cmd;
> > +struct builtin_table;
> >
> > void nft_cache_level_set(struct nft_handle *h, int level,
> > const struct nft_cmd *cmd);
> > @@ -12,6 +13,8 @@ void flush_chain_cache(struct nft_handle *h, const char *tablename);
> > int flush_rule_cache(struct nft_handle *h, const char *table,
> > struct nftnl_chain *c);
> > void nft_cache_build(struct nft_handle *h);
> > +int nft_cache_add_chain(struct nft_handle *h, const struct builtin_table *t,
> > + struct nftnl_chain *c);
> >
> > struct nftnl_chain_list *
> > nft_chain_list_get(struct nft_handle *h, const char *table, const char *chain);
> > diff --git a/iptables/nft.c b/iptables/nft.c
> > index 4f40be2e60252..8e1a33ba69bf1 100644
> > --- a/iptables/nft.c
> > +++ b/iptables/nft.c
> > @@ -695,7 +695,7 @@ static void nft_chain_builtin_add(struct nft_handle *h,
> > return;
> >
> > batch_chain_add(h, NFT_COMPAT_CHAIN_ADD, c);
> > - nftnl_chain_list_add_tail(c, h->cache->table[table->type].chains);
> > + nft_cache_add_chain(h, table, c);
> > }
> >
> > /* find if built-in table already exists */
> > @@ -1696,7 +1696,7 @@ int nft_rule_flush(struct nft_handle *h, const char *chain, const char *table,
> >
> > int nft_chain_user_add(struct nft_handle *h, const char *chain, const char *table)
> > {
> > - struct nftnl_chain_list *list;
> > + const struct builtin_table *t;
> > struct nftnl_chain *c;
> > int ret;
> >
> > @@ -1720,9 +1720,8 @@ int nft_chain_user_add(struct nft_handle *h, const char *chain, const char *tabl
> >
> > ret = batch_chain_add(h, NFT_COMPAT_CHAIN_USER_ADD, c);
> >
> > - list = nft_chain_list_get(h, table, chain);
> > - if (list)
> > - nftnl_chain_list_add(c, list);
> > + t = nft_table_builtin_find(h, table);
>
> I'd add here:
>
> assert(t);
>
> just in case this is ever crashing here, let's make it nice.
It is not needed: In nft_chain_user_add(), there is a call to
nft_chain_exists() earlier which implicitly checks that
nft_table_builtin_find() succeeds with given table name.
The other two places the wrapper is used are fine, too:
In nft_chain_builtin_add(), the builtin_table pointer was passed via
parameters from nft_xt_builtin_init() which itself does a NULL-pointer
check.
In nft_chain_restore(), the table's name is passed from state->curtable
pointer in xtables_restore_parse_line() which in turn was acquired via
nft_table_builtin_find(). (I actually plan to pass this builtin_table
pointer around instead of the table name at some point.)
Cheers, Phil
