When initializing builtin chains, fetch only the chain to add from
kernel to reduce overhead in case kernel ruleset contains many chains.
Given the flexibility of nft_chain_list_get() this is not a problem, but
care has to be taken when updating the table's chain list: Since a
command like 'iptables-nft -F INPUT' causes two invocations of
nft_chain_list_get() with same arguments, the same chain will be fetched
from kernel twice. To handle this, simply clearing chain list from
fetch_chain_cache() is not an option as list elements might be
referenced by pending batch jobs. Instead abort in nftnl_chain_list_cb()
if a chain with same name already exists in the list. Also, the call to
fetch_table_cache() must happen conditionally to avoid leaking existing
table list.
Signed-off-by: Phil Sutter <p...@nwl.cc>
---
iptables/nft.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff --git a/iptables/nft.c b/iptables/nft.c
index 5eb129461dab2..66011a8066ed9 100644
--- a/iptables/nft.c
+++ b/iptables/nft.c
@@ -750,15 +750,15 @@ nft_chain_builtin_find(const struct builtin_table *t,
const char *chain)
static void nft_chain_builtin_init(struct nft_handle *h,
const struct builtin_table *table)
{
- struct nftnl_chain_list *list = nft_chain_list_get(h, table->name,
NULL);
+ struct nftnl_chain_list *list;
struct nftnl_chain *c;
int i;
- if (!list)
- return;
-
/* Initialize built-in chains if they don't exist yet */
for (i=0; i < NF_INET_NUMHOOKS && table->chains[i].name != NULL; i++) {
+ list = nft_chain_list_get(h, table->name,
table->chains[i].name);
+ if (!list)
+ continue;
c = nftnl_chain_list_lookup_byname(list, table->chains[i].name);
if (c != NULL)
@@ -1374,7 +1374,8 @@ static int nftnl_chain_list_cb(const struct nlmsghdr
*nlh, void *data)
{
struct nft_handle *h = data;
const struct builtin_table *t;
- struct nftnl_chain *c;
+ struct nftnl_chain *c, *c2;
+ const char *tname, *cname;
c = nftnl_chain_alloc();
if (c == NULL)
@@ -1383,11 +1384,17 @@ static int nftnl_chain_list_cb(const struct nlmsghdr
*nlh, void *data)
if (nftnl_chain_nlmsg_parse(nlh, c) < 0)
goto out;
- t = nft_table_builtin_find(h,
- nftnl_chain_get_str(c, NFTNL_CHAIN_TABLE));
+ tname = nftnl_chain_get_str(c, NFTNL_CHAIN_TABLE);
+ t = nft_table_builtin_find(h, tname);
if (!t)
goto out;
+ cname = nftnl_chain_get_str(c, NFTNL_CHAIN_NAME);
+ c2 = nftnl_chain_list_lookup_byname(h->cache->table[t->type].chains,
+ cname);
+ if (c2)
+ goto out;
+
nftnl_chain_list_add_tail(c, h->cache->table[t->type].chains);
return MNL_CB_OK;
@@ -1447,7 +1454,8 @@ static int fetch_chain_cache(struct nft_handle *h, const
char *table, const char
struct nlmsghdr *nlh;
int i, ret;
- fetch_table_cache(h);
+ if (!h->cache->tables)
+ fetch_table_cache(h);
for (i = 0; i < NFT_TABLE_MAX; i++) {
enum nft_table_type type = h->tables[i].type;
@@ -1462,10 +1470,9 @@ static int fetch_chain_cache(struct nft_handle *h, const
char *table, const char
if (chain && table && strcmp(table, h->tables[i].name))
continue;
- if (h->cache->table[type].chains)
- nftnl_chain_list_free(h->cache->table[type].chains);
+ if (!h->cache->table[type].chains)
+ h->cache->table[type].chains = nftnl_chain_list_alloc();
- h->cache->table[type].chains = nftnl_chain_list_alloc();
if (!h->cache->table[type].chains)
return -1;
}
--
2.23.0
