From cff8cdcc8f33c1c3fec5a213f17f49b492be2216 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Tue, 10 Sep 2024 21:24:25 -0700 Subject: [PATCH] mptcp: initialize sock lock with its own lockdep keys In mptcp_pm_nl_create_listen_socket(), we already initialize mptcp sock lock with mptcp_slock_keys and mptcp_keys. But that is not sufficient, at least mptcp_init_sock() and mptcp_sk_clone_init() still miss it. As reported by syzbot, mptcp_sk_clone_init() is challenging due to that sk_clone_lock() immediately locks the new sock after preliminary initialization. To amend that, introduce ->init_clone() for struct proto and call it right after the sock_lock_init(), so now mptcp sock could initialize the sock lock again with its own lockdep keys. This patch does not fix any real deadlock, it only makes lockdep happy. Fixes: 58b09919626b ("mptcp: create msk early") Reported-by: syzbot+f4aacdfef2c6a6529c3e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f4aacdfef2c6a6529c3e Cc: Matthieu Baerts Cc: Mat Martineau Cc: Geliang Tang Signed-off-by: Cong Wang Message-Id: <20240911042425.978665-1-xiyou.wangcong@gmail.com> --- include/net/sock.h | 1 + net/core/sock.c | 2 ++ net/mptcp/pm_netlink.c | 16 +--------------- net/mptcp/protocol.c | 22 ++++++++++++++++++++++ net/mptcp/protocol.h | 1 + 5 files changed, 27 insertions(+), 15 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index f51d61fab059..2e06e720071a 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1226,6 +1226,7 @@ struct proto { int (*ioctl)(struct sock *sk, int cmd, int *karg); int (*init)(struct sock *sk); + void (*init_clone)(struct sock *sk); void (*destroy)(struct sock *sk); void (*shutdown)(struct sock *sk, int how); int (*setsockopt)(struct sock *sk, int level, diff --git a/net/core/sock.c b/net/core/sock.c index 468b1239606c..d37e6efc7f91 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2325,6 +2325,8 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) } sk_node_init(&newsk->sk_node); sock_lock_init(newsk); + if (prot->init_clone) + prot->init_clone(newsk); bh_lock_sock(newsk); newsk->sk_backlog.head = newsk->sk_backlog.tail = NULL; newsk->sk_backlog.len = 0; diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index fe34297ea6dc..a82b68cc1faf 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -1067,13 +1067,9 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet, return ret; } -static struct lock_class_key mptcp_slock_keys[2]; -static struct lock_class_key mptcp_keys[2]; - static int mptcp_pm_nl_create_listen_socket(struct sock *sk, struct mptcp_pm_addr_entry *entry) { - bool is_ipv6 = sk->sk_family == AF_INET6; int addrlen = sizeof(struct sockaddr_in); struct sockaddr_storage addr; struct sock *newsk, *ssk; @@ -1089,17 +1085,7 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk, if (!newsk) return -EINVAL; - /* The subflow socket lock is acquired in a nested to the msk one - * in several places, even by the TCP stack, and this msk is a kernel - * socket: lockdep complains. Instead of propagating the _nested - * modifiers in several places, re-init the lock class for the msk - * socket to an mptcp specific one. - */ - sock_lock_init_class_and_name(newsk, - is_ipv6 ? "mlock-AF_INET6" : "mlock-AF_INET", - &mptcp_slock_keys[is_ipv6], - is_ipv6 ? "msk_lock-AF_INET6" : "msk_lock-AF_INET", - &mptcp_keys[is_ipv6]); + mptcp_sock_lock_init(newsk); lock_sock(newsk); ssk = __mptcp_nmpc_sk(mptcp_sk(newsk)); diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 3b837765c84b..7ecaa83794b2 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2839,6 +2839,7 @@ static int mptcp_init_sock(struct sock *sk) int ret; __mptcp_init_sock(sk); + mptcp_sock_lock_init(sk); if (!mptcp_is_enabled(net)) return -ENOPROTOOPT; @@ -2865,6 +2866,26 @@ static int mptcp_init_sock(struct sock *sk) return 0; } +static struct lock_class_key mptcp_slock_keys[2]; +static struct lock_class_key mptcp_keys[2]; + +void mptcp_sock_lock_init(struct sock *sk) +{ + bool is_ipv6 = sk->sk_family == AF_INET6; + + /* The subflow socket lock is acquired in a nested to the msk one + * in several places, even by the TCP stack, and this msk is a kernel + * socket: lockdep complains. Instead of propagating the _nested + * modifiers in several places, re-init the lock class for the msk + * socket to an mptcp specific one. + */ + sock_lock_init_class_and_name(sk, + is_ipv6 ? "mlock-AF_INET6" : "mlock-AF_INET", + &mptcp_slock_keys[is_ipv6], + is_ipv6 ? "msk_lock-AF_INET6" : "msk_lock-AF_INET", + &mptcp_keys[is_ipv6]); +} + static void __mptcp_clear_xmit(struct sock *sk) { struct mptcp_sock *msk = mptcp_sk(sk); @@ -3797,6 +3818,7 @@ static struct proto mptcp_prot = { .name = "MPTCP", .owner = THIS_MODULE, .init = mptcp_init_sock, + .init_clone = mptcp_sock_lock_init, .connect = mptcp_connect, .disconnect = mptcp_disconnect, .close = mptcp_close, diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index c3942416fa3a..819a193c0d88 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -812,6 +812,7 @@ void __init mptcp_proto_init(void); int __init mptcp_proto_v6_init(void); #endif +void mptcp_sock_lock_init(struct sock *sk); struct sock *mptcp_sk_clone_init(const struct sock *sk, const struct mptcp_options_received *mp_opt, struct sock *ssk,