linux/net/ipv4/udp_bpf.c
Cong Wang 51e0158a54 skmsg: Pass psock pointer to ->psock_update_sk_prot()
Using sk_psock() to retrieve psock pointer from sock requires
RCU read lock, but we already get psock pointer before calling
->psock_update_sk_prot() in both cases, so we can just pass it
without bothering sk_psock().

Fixes: 8a59f9d1e3 ("sock: Introduce sk->sk_prot->psock_update_sk_prot()")
Reported-by: syzbot+320a3bc8d80f478c37e4@syzkaller.appspotmail.com
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+320a3bc8d80f478c37e4@syzkaller.appspotmail.com
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210407032111.33398-1-xiyou.wangcong@gmail.com
2021-04-12 17:34:27 +02:00

123 lines
2.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020 Cloudflare Ltd https://cloudflare.com */
#include <linux/skmsg.h>
#include <net/sock.h>
#include <net/udp.h>
#include <net/inet_common.h>
#include "udp_impl.h"
static struct proto *udpv6_prot_saved __read_mostly;
static int sk_udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
int noblock, int flags, int *addr_len)
{
#if IS_ENABLED(CONFIG_IPV6)
if (sk->sk_family == AF_INET6)
return udpv6_prot_saved->recvmsg(sk, msg, len, noblock, flags,
addr_len);
#endif
return udp_prot.recvmsg(sk, msg, len, noblock, flags, addr_len);
}
static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
int nonblock, int flags, int *addr_len)
{
struct sk_psock *psock;
int copied, ret;
if (unlikely(flags & MSG_ERRQUEUE))
return inet_recv_error(sk, msg, len, addr_len);
psock = sk_psock_get(sk);
if (unlikely(!psock))
return sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
lock_sock(sk);
if (sk_psock_queue_empty(psock)) {
ret = sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
goto out;
}
msg_bytes_ready:
copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
if (!copied) {
int data, err = 0;
long timeo;
timeo = sock_rcvtimeo(sk, nonblock);
data = sk_msg_wait_data(sk, psock, flags, timeo, &err);
if (data) {
if (!sk_psock_queue_empty(psock))
goto msg_bytes_ready;
ret = sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
goto out;
}
if (err) {
ret = err;
goto out;
}
copied = -EAGAIN;
}
ret = copied;
out:
release_sock(sk);
sk_psock_put(sk, psock);
return ret;
}
enum {
UDP_BPF_IPV4,
UDP_BPF_IPV6,
UDP_BPF_NUM_PROTS,
};
static DEFINE_SPINLOCK(udpv6_prot_lock);
static struct proto udp_bpf_prots[UDP_BPF_NUM_PROTS];
static void udp_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
{
*prot = *base;
prot->unhash = sock_map_unhash;
prot->close = sock_map_close;
prot->recvmsg = udp_bpf_recvmsg;
}
static void udp_bpf_check_v6_needs_rebuild(struct proto *ops)
{
if (unlikely(ops != smp_load_acquire(&udpv6_prot_saved))) {
spin_lock_bh(&udpv6_prot_lock);
if (likely(ops != udpv6_prot_saved)) {
udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV6], ops);
smp_store_release(&udpv6_prot_saved, ops);
}
spin_unlock_bh(&udpv6_prot_lock);
}
}
static int __init udp_bpf_v4_build_proto(void)
{
udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV4], &udp_prot);
return 0;
}
core_initcall(udp_bpf_v4_build_proto);
int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
{
int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
if (restore) {
sk->sk_write_space = psock->saved_write_space;
WRITE_ONCE(sk->sk_prot, psock->sk_proto);
return 0;
}
if (sk->sk_family == AF_INET6)
udp_bpf_check_v6_needs_rebuild(psock->sk_proto);
WRITE_ONCE(sk->sk_prot, &udp_bpf_prots[family]);
return 0;
}
EXPORT_SYMBOL_GPL(udp_bpf_update_proto);