This is a note to let you know that I've just added the patch titled
netfilter: nf_tables: Add locking for NFT_MSG_GETOBJ_RESET requests
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-nf_tables-add-locking-for-nft_msg_getobj_r.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit fd171f72b640cf8201c3dcb6554051a0c9e8cddf
Author: Phil Sutter <phil@xxxxxx>
Date: Fri Aug 9 15:07:32 2024 +0200
netfilter: nf_tables: Add locking for NFT_MSG_GETOBJ_RESET requests
[ Upstream commit bd662c4218f9648e888bebde9468146965f3f8a0 ]
Objects' dump callbacks are not concurrency-safe per-se with reset bit
set. If two CPUs perform a reset at the same time, at least counter and
quota objects suffer from value underrun.
Prevent this by introducing dedicated locking callbacks for nfnetlink
and the asynchronous dump handling to serialize access.
Fixes: 43da04a593d8 ("netfilter: nf_tables: atomic dump and reset for stateful objects")
Signed-off-by: Phil Sutter <phil@xxxxxx>
Reviewed-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 88eacfe746810..63b7be0a95d04 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -7482,6 +7482,19 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
return skb->len;
}
+static int nf_tables_dumpreset_obj(struct sk_buff *skb,
+ struct netlink_callback *cb)
+{
+ struct nftables_pernet *nft_net = nft_pernet(sock_net(skb->sk));
+ int ret;
+
+ mutex_lock(&nft_net->commit_mutex);
+ ret = nf_tables_dump_obj(skb, cb);
+ mutex_unlock(&nft_net->commit_mutex);
+
+ return ret;
+}
+
static int nf_tables_dump_obj_start(struct netlink_callback *cb)
{
struct nft_obj_dump_ctx *ctx = (void *)cb->ctx;
@@ -7498,12 +7511,18 @@ static int nf_tables_dump_obj_start(struct netlink_callback *cb)
if (nla[NFTA_OBJ_TYPE])
ctx->type = ntohl(nla_get_be32(nla[NFTA_OBJ_TYPE]));
- if (NFNL_MSG_TYPE(cb->nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET)
- ctx->reset = true;
-
return 0;
}
+static int nf_tables_dumpreset_obj_start(struct netlink_callback *cb)
+{
+ struct nft_obj_dump_ctx *ctx = (void *)cb->ctx;
+
+ ctx->reset = true;
+
+ return nf_tables_dump_obj_start(cb);
+}
+
static int nf_tables_dump_obj_done(struct netlink_callback *cb)
{
struct nft_obj_dump_ctx *ctx = (void *)cb->ctx;
@@ -7562,18 +7581,43 @@ nf_tables_getobj_single(u32 portid, const struct nfnl_info *info,
static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info,
const struct nlattr * const nla[])
+{
+ u32 portid = NETLINK_CB(skb).portid;
+ struct sk_buff *skb2;
+
+ if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
+ struct netlink_dump_control c = {
+ .start = nf_tables_dump_obj_start,
+ .dump = nf_tables_dump_obj,
+ .done = nf_tables_dump_obj_done,
+ .module = THIS_MODULE,
+ .data = (void *)nla,
+ };
+
+ return nft_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c);
+ }
+
+ skb2 = nf_tables_getobj_single(portid, info, nla, false);
+ if (IS_ERR(skb2))
+ return PTR_ERR(skb2);
+
+ return nfnetlink_unicast(skb2, info->net, portid);
+}
+
+static int nf_tables_getobj_reset(struct sk_buff *skb,
+ const struct nfnl_info *info,
+ const struct nlattr * const nla[])
{
struct nftables_pernet *nft_net = nft_pernet(info->net);
u32 portid = NETLINK_CB(skb).portid;
struct net *net = info->net;
struct sk_buff *skb2;
- bool reset = false;
char *buf;
if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
struct netlink_dump_control c = {
- .start = nf_tables_dump_obj_start,
- .dump = nf_tables_dump_obj,
+ .start = nf_tables_dumpreset_obj_start,
+ .dump = nf_tables_dumpreset_obj,
.done = nf_tables_dump_obj_done,
.module = THIS_MODULE,
.data = (void *)nla,
@@ -7582,16 +7626,18 @@ static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info,
return nft_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c);
}
- if (NFNL_MSG_TYPE(info->nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET)
- reset = true;
+ if (!try_module_get(THIS_MODULE))
+ return -EINVAL;
+ rcu_read_unlock();
+ mutex_lock(&nft_net->commit_mutex);
+ skb2 = nf_tables_getobj_single(portid, info, nla, true);
+ mutex_unlock(&nft_net->commit_mutex);
+ rcu_read_lock();
+ module_put(THIS_MODULE);
- skb2 = nf_tables_getobj_single(portid, info, nla, reset);
if (IS_ERR(skb2))
return PTR_ERR(skb2);
- if (!reset)
- return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
-
buf = kasprintf(GFP_ATOMIC, "%.*s:%u",
nla_len(nla[NFTA_OBJ_TABLE]),
(char *)nla_data(nla[NFTA_OBJ_TABLE]),
@@ -8807,7 +8853,7 @@ static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {
.policy = nft_obj_policy,
},
[NFT_MSG_GETOBJ_RESET] = {
- .call = nf_tables_getobj,
+ .call = nf_tables_getobj_reset,
.type = NFNL_CB_RCU,
.attr_count = NFTA_OBJ_MAX,
.policy = nft_obj_policy,
