forked from mirrors/linux
83f3153556
As of now, only AF_UNIX datagram socket supports sockmap. But
unix_proto is shared for all kinds of AF_UNIX sockets, so we
have to check the socket type in unix_bpf_update_proto() to
explicitly reject other types, otherwise they could be added
into sockmap, too.
Fixes: c63829182c ("af_unix: Implement ->psock_update_sk_prot()")
Reported-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210731195038.8084-1-xiyou.wangcong@gmail.com
125 lines
3.1 KiB
C
125 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Cong Wang <cong.wang@bytedance.com> */
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#include <linux/skmsg.h>
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#include <linux/bpf.h>
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#include <net/sock.h>
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#include <net/af_unix.h>
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#define unix_sk_has_data(__sk, __psock) \
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({ !skb_queue_empty(&__sk->sk_receive_queue) || \
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!skb_queue_empty(&__psock->ingress_skb) || \
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!list_empty(&__psock->ingress_msg); \
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})
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static int unix_msg_wait_data(struct sock *sk, struct sk_psock *psock,
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long timeo)
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{
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DEFINE_WAIT_FUNC(wait, woken_wake_function);
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struct unix_sock *u = unix_sk(sk);
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int ret = 0;
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if (sk->sk_shutdown & RCV_SHUTDOWN)
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return 1;
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if (!timeo)
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return ret;
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add_wait_queue(sk_sleep(sk), &wait);
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sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
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if (!unix_sk_has_data(sk, psock)) {
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mutex_unlock(&u->iolock);
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wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
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mutex_lock(&u->iolock);
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ret = unix_sk_has_data(sk, psock);
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}
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sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
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remove_wait_queue(sk_sleep(sk), &wait);
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return ret;
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}
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static int unix_dgram_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
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size_t len, int nonblock, int flags,
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int *addr_len)
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{
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struct unix_sock *u = unix_sk(sk);
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struct sk_psock *psock;
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int copied;
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psock = sk_psock_get(sk);
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if (unlikely(!psock))
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return __unix_dgram_recvmsg(sk, msg, len, flags);
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mutex_lock(&u->iolock);
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if (!skb_queue_empty(&sk->sk_receive_queue) &&
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sk_psock_queue_empty(psock)) {
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mutex_unlock(&u->iolock);
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sk_psock_put(sk, psock);
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return __unix_dgram_recvmsg(sk, msg, len, flags);
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}
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msg_bytes_ready:
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copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
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if (!copied) {
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long timeo;
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int data;
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timeo = sock_rcvtimeo(sk, nonblock);
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data = unix_msg_wait_data(sk, psock, timeo);
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if (data) {
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if (!sk_psock_queue_empty(psock))
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goto msg_bytes_ready;
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mutex_unlock(&u->iolock);
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sk_psock_put(sk, psock);
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return __unix_dgram_recvmsg(sk, msg, len, flags);
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}
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copied = -EAGAIN;
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}
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mutex_unlock(&u->iolock);
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sk_psock_put(sk, psock);
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return copied;
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}
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static struct proto *unix_prot_saved __read_mostly;
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static DEFINE_SPINLOCK(unix_prot_lock);
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static struct proto unix_bpf_prot;
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static void unix_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
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{
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*prot = *base;
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prot->close = sock_map_close;
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prot->recvmsg = unix_dgram_bpf_recvmsg;
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}
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static void unix_bpf_check_needs_rebuild(struct proto *ops)
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{
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if (unlikely(ops != smp_load_acquire(&unix_prot_saved))) {
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spin_lock_bh(&unix_prot_lock);
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if (likely(ops != unix_prot_saved)) {
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unix_bpf_rebuild_protos(&unix_bpf_prot, ops);
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smp_store_release(&unix_prot_saved, ops);
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}
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spin_unlock_bh(&unix_prot_lock);
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}
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}
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int unix_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
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{
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if (sk->sk_type != SOCK_DGRAM)
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return -EOPNOTSUPP;
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if (restore) {
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sk->sk_write_space = psock->saved_write_space;
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WRITE_ONCE(sk->sk_prot, psock->sk_proto);
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return 0;
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}
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unix_bpf_check_needs_rebuild(psock->sk_proto);
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WRITE_ONCE(sk->sk_prot, &unix_bpf_prot);
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return 0;
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}
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void __init unix_bpf_build_proto(void)
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{
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unix_bpf_rebuild_protos(&unix_bpf_prot, &unix_proto);
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}
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