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rtnetlink: change nlk->cb_mutex role 

[ Upstream commit e39951d965bf58b5aba7f61dc1140dcb8271af22 ]

In commit af65bdfce9 ("[NETLINK]: Switch cb_lock spinlock
to mutex and allow to override it"), Patrick McHardy used
a common mutex to protect both nlk->cb and the dump() operations.

The override is used for rtnl dumps, registered with
rntl_register() and rntl_register_module().

We want to be able to opt-out some dump() operations
to not acquire RTNL, so we need to protect nlk->cb
with a per socket mutex.

This patch renames nlk->cb_def_mutex to nlk->nl_cb_mutex

The optional pointer to the mutex used to protect dump()
call is stored in nlk->dump_cb_mutex

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 5be2062e3080 ("mpls: Handle error of rtnl_register_module().")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet 2024-02-22 10:50:14 +00:00 committed by Greg Kroah-Hartman
parent f4df31a051
commit c8c76f1550
2 changed files with 21 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
net/netlink/af_netlink.c
View File

@ -636,7 +636,7 @@ static struct proto netlink_proto = {
};
static int __netlink_create(struct net *net, struct socket *sock,
struct mutex *cb_mutex, int protocol,
struct mutex *dump_cb_mutex, int protocol,
int kern)
{
struct sock *sk;
@ -651,15 +651,11 @@ static int __netlink_create(struct net *net, struct socket *sock,
sock_init_data(sock, sk);
nlk = nlk_sk(sk);
if (cb_mutex) {
nlk->cb_mutex = cb_mutex;
} else {
nlk->cb_mutex = &nlk->cb_def_mutex;
mutex_init(nlk->cb_mutex);
lockdep_set_class_and_name(nlk->cb_mutex,
mutex_init(&nlk->nl_cb_mutex);
lockdep_set_class_and_name(&nlk->nl_cb_mutex,
nlk_cb_mutex_keys + protocol,
nlk_cb_mutex_key_strings[protocol]);
}
nlk->dump_cb_mutex = dump_cb_mutex;
init_waitqueue_head(&nlk->wait);
sk->sk_destruct = netlink_sock_destruct;
@ -2211,7 +2207,7 @@ static int netlink_dump(struct sock *sk, bool lock_taken)
int alloc_size;
if (!lock_taken)
mutex_lock(nlk->cb_mutex);
mutex_lock(&nlk->nl_cb_mutex);
if (!nlk->cb_running) {
err = -EINVAL;
goto errout_skb;
@ -2263,14 +2259,22 @@ static int netlink_dump(struct sock *sk, bool lock_taken)
netlink_skb_set_owner_r(skb, sk);
if (nlk->dump_done_errno > 0) {
struct mutex *extra_mutex = nlk->dump_cb_mutex;
cb->extack = &extack;
if (extra_mutex)
mutex_lock(extra_mutex);
nlk->dump_done_errno = cb->dump(skb, cb);
if (extra_mutex)
mutex_unlock(extra_mutex);
cb->extack = NULL;
}
if (nlk->dump_done_errno > 0 ||
skb_tailroom(skb) < nlmsg_total_size(sizeof(nlk->dump_done_errno))) {
mutex_unlock(nlk->cb_mutex);
mutex_unlock(&nlk->nl_cb_mutex);
if (sk_filter(sk, skb))
kfree_skb(skb);
@ -2304,13 +2308,13 @@ static int netlink_dump(struct sock *sk, bool lock_taken)
WRITE_ONCE(nlk->cb_running, false);
module = cb->module;
skb = cb->skb;
mutex_unlock(nlk->cb_mutex);
mutex_unlock(&nlk->nl_cb_mutex);
module_put(module);
consume_skb(skb);
return 0;
errout_skb:
mutex_unlock(nlk->cb_mutex);
mutex_unlock(&nlk->nl_cb_mutex);
kfree_skb(skb);
return err;
}
@ -2333,7 +2337,7 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
}
nlk = nlk_sk(sk);
mutex_lock(nlk->cb_mutex);
mutex_lock(&nlk->nl_cb_mutex);
/* A dump is in progress... */
if (nlk->cb_running) {
ret = -EBUSY;
@ -2384,7 +2388,7 @@ error_put:
module_put(control->module);
error_unlock:
sock_put(sk);
mutex_unlock(nlk->cb_mutex);
mutex_unlock(&nlk->nl_cb_mutex);
error_free:
kfree_skb(skb);
return ret;

5
net/netlink/af_netlink.h
View File

@ -39,8 +39,9 @@ struct netlink_sock {
bool cb_running;
int dump_done_errno;
struct netlink_callback cb;
struct mutex *cb_mutex;
struct mutex cb_def_mutex;
struct mutex nl_cb_mutex;
struct mutex *dump_cb_mutex;
void (*netlink_rcv)(struct sk_buff *skb);
int (*netlink_bind)(struct net *net, int group);
void (*netlink_unbind)(struct net *net, int group);