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-rw-r--r--net/sched/cls_api.c96
1 files changed, 71 insertions, 25 deletions
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 869ae44d7631..8e2ac785f6fd 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -883,28 +883,62 @@ static struct tcf_block *tcf_block_refcnt_get(struct net *net, u32 block_index)
return block;
}
-static void tcf_block_flush_all_chains(struct tcf_block *block)
+static struct tcf_chain *
+__tcf_get_next_chain(struct tcf_block *block, struct tcf_chain *chain)
{
- struct tcf_chain *chain;
+ mutex_lock(&block->lock);
+ if (chain)
+ chain = list_is_last(&chain->list, &block->chain_list) ?
+ NULL : list_next_entry(chain, list);
+ else
+ chain = list_first_entry_or_null(&block->chain_list,
+ struct tcf_chain, list);
- /* Hold a refcnt for all chains, so that they don't disappear
- * while we are iterating.
- */
- list_for_each_entry(chain, &block->chain_list, list)
+ /* skip all action-only chains */
+ while (chain && tcf_chain_held_by_acts_only(chain))
+ chain = list_is_last(&chain->list, &block->chain_list) ?
+ NULL : list_next_entry(chain, list);
+
+ if (chain)
tcf_chain_hold(chain);
+ mutex_unlock(&block->lock);
- list_for_each_entry(chain, &block->chain_list, list)
- tcf_chain_flush(chain);
+ return chain;
}
-static void tcf_block_put_all_chains(struct tcf_block *block)
+/* Function to be used by all clients that want to iterate over all chains on
+ * block. It properly obtains block->lock and takes reference to chain before
+ * returning it. Users of this function must be tolerant to concurrent chain
+ * insertion/deletion or ensure that no concurrent chain modification is
+ * possible. Note that all netlink dump callbacks cannot guarantee to provide
+ * consistent dump because rtnl lock is released each time skb is filled with
+ * data and sent to user-space.
+ */
+
+struct tcf_chain *
+tcf_get_next_chain(struct tcf_block *block, struct tcf_chain *chain)
{
- struct tcf_chain *chain, *tmp;
+ struct tcf_chain *chain_next = __tcf_get_next_chain(block, chain);
- /* At this point, all the chains should have refcnt >= 1. */
- list_for_each_entry_safe(chain, tmp, &block->chain_list, list) {
- tcf_chain_put_explicitly_created(chain);
+ if (chain)
tcf_chain_put(chain);
+
+ return chain_next;
+}
+EXPORT_SYMBOL(tcf_get_next_chain);
+
+static void tcf_block_flush_all_chains(struct tcf_block *block)
+{
+ struct tcf_chain *chain;
+
+ /* Last reference to block. At this point chains cannot be added or
+ * removed concurrently.
+ */
+ for (chain = tcf_get_next_chain(block, NULL);
+ chain;
+ chain = tcf_get_next_chain(block, chain)) {
+ tcf_chain_put_explicitly_created(chain);
+ tcf_chain_flush(chain);
}
}
@@ -923,8 +957,6 @@ static void __tcf_block_put(struct tcf_block *block, struct Qdisc *q,
mutex_unlock(&block->lock);
if (tcf_block_shared(block))
tcf_block_remove(block, block->net);
- if (!free_block)
- tcf_block_flush_all_chains(block);
if (q)
tcf_block_offload_unbind(block, q, ei);
@@ -932,7 +964,7 @@ static void __tcf_block_put(struct tcf_block *block, struct Qdisc *q,
if (free_block)
tcf_block_destroy(block);
else
- tcf_block_put_all_chains(block);
+ tcf_block_flush_all_chains(block);
} else if (q) {
tcf_block_offload_unbind(block, q, ei);
}
@@ -1266,11 +1298,15 @@ tcf_block_playback_offloads(struct tcf_block *block, tc_setup_cb_t *cb,
void *cb_priv, bool add, bool offload_in_use,
struct netlink_ext_ack *extack)
{
- struct tcf_chain *chain;
+ struct tcf_chain *chain, *chain_prev;
struct tcf_proto *tp;
int err;
- list_for_each_entry(chain, &block->chain_list, list) {
+ for (chain = __tcf_get_next_chain(block, NULL);
+ chain;
+ chain_prev = chain,
+ chain = __tcf_get_next_chain(block, chain),
+ tcf_chain_put(chain_prev)) {
for (tp = rtnl_dereference(chain->filter_chain); tp;
tp = rtnl_dereference(tp->next)) {
if (tp->ops->reoffload) {
@@ -1289,6 +1325,7 @@ tcf_block_playback_offloads(struct tcf_block *block, tc_setup_cb_t *cb,
return 0;
err_playback_remove:
+ tcf_chain_put(chain);
tcf_block_playback_offloads(block, cb, cb_priv, false, offload_in_use,
extack);
return err;
@@ -2023,11 +2060,11 @@ static bool tcf_chain_dump(struct tcf_chain *chain, struct Qdisc *q, u32 parent,
/* called with RTNL */
static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
{
+ struct tcf_chain *chain, *chain_prev;
struct net *net = sock_net(skb->sk);
struct nlattr *tca[TCA_MAX + 1];
struct Qdisc *q = NULL;
struct tcf_block *block;
- struct tcf_chain *chain;
struct tcmsg *tcm = nlmsg_data(cb->nlh);
long index_start;
long index;
@@ -2091,12 +2128,17 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
index_start = cb->args[0];
index = 0;
- list_for_each_entry(chain, &block->chain_list, list) {
+ for (chain = __tcf_get_next_chain(block, NULL);
+ chain;
+ chain_prev = chain,
+ chain = __tcf_get_next_chain(block, chain),
+ tcf_chain_put(chain_prev)) {
if (tca[TCA_CHAIN] &&
nla_get_u32(tca[TCA_CHAIN]) != chain->index)
continue;
if (!tcf_chain_dump(chain, q, parent, skb, cb,
index_start, &index)) {
+ tcf_chain_put(chain);
err = -EMSGSIZE;
break;
}
@@ -2364,11 +2406,11 @@ errout_block_locked:
/* called with RTNL */
static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb)
{
+ struct tcf_chain *chain, *chain_prev;
struct net *net = sock_net(skb->sk);
struct nlattr *tca[TCA_MAX + 1];
struct Qdisc *q = NULL;
struct tcf_block *block;
- struct tcf_chain *chain;
struct tcmsg *tcm = nlmsg_data(cb->nlh);
long index_start;
long index;
@@ -2432,7 +2474,11 @@ static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb)
index_start = cb->args[0];
index = 0;
- list_for_each_entry(chain, &block->chain_list, list) {
+ for (chain = __tcf_get_next_chain(block, NULL);
+ chain;
+ chain_prev = chain,
+ chain = __tcf_get_next_chain(block, chain),
+ tcf_chain_put(chain_prev)) {
if ((tca[TCA_CHAIN] &&
nla_get_u32(tca[TCA_CHAIN]) != chain->index))
continue;
@@ -2440,14 +2486,14 @@ static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb)
index++;
continue;
}
- if (tcf_chain_held_by_acts_only(chain))
- continue;
err = tc_chain_fill_node(chain, net, skb, block,
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, NLM_F_MULTI,
RTM_NEWCHAIN);
- if (err <= 0)
+ if (err <= 0) {
+ tcf_chain_put(chain);
break;
+ }
index++;
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.