From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
We have to implement unix_dgram_bpf_recvmsg() to replace the
original ->recvmsg() to retrieve skmsg from ingress_msg.
AF_UNIX is again special here because the lack of
sk_prot->recvmsg(). I simply add a special case inside
unix_dgram_recvmsg() to call sk->sk_prot->recvmsg() directly.
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Cc: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
---
include/net/af_unix.h | 3 +++
net/unix/af_unix.c | 21 ++++++++++++++++---
net/unix/unix_bpf.c | 49 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 70 insertions(+), 3 deletions(-)
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index fa75f899e88a..f6c43667e995 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -82,6 +82,9 @@ static inline struct unix_sock *unix_sk(const struct sock *sk)
long unix_inq_len(struct sock *sk);
long unix_outq_len(struct sock *sk);
+int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
+ int nonblock, int flags, int *addr_len);
+
#ifdef CONFIG_SYSCTL
int unix_sysctl_register(struct net *net);
void unix_sysctl_unregister(struct net *net);
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 21c4406f879b..eebcd6f7ef88 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2094,11 +2094,11 @@ static void unix_copy_addr(struct msghdr *msg, struct sock *sk)
}
}
-static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
- size_t size, int flags)
+int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
+ int nonblock, int flags, int *addr_len)
{
struct scm_cookie scm;
- struct sock *sk = sock->sk;
+ struct socket *sock = sk->sk_socket;
struct unix_sock *u = unix_sk(sk);
struct sk_buff *skb, *last;
long timeo;
@@ -2201,6 +2201,21 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
return err;
}
+static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
+ int flags)
+{
+ struct sock *sk = sock->sk;
+ int addr_len = 0;
+
+#ifdef CONFIG_BPF_SOCK_MAP
+ if (sk->sk_prot != &unix_proto)
+ return sk->sk_prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT,
+ flags & ~MSG_DONTWAIT, &addr_len);
+#endif
+ return __unix_dgram_recvmsg(sk, msg, size, flags & MSG_DONTWAIT,
+ flags, &addr_len);
+}
+
int unix_read_sock(struct sock *sk, read_descriptor_t *desc,
sk_read_actor_t recv_actor)
{
diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
index 2e6a26ec4958..570261fd18cd 100644
--- a/net/unix/unix_bpf.c
+++ b/net/unix/unix_bpf.c
@@ -5,6 +5,54 @@
#include <net/sock.h>
#include <net/af_unix.h>
+static int unix_dgram_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;
+
+ psock = sk_psock_get(sk);
+ if (unlikely(!psock))
+ return __unix_dgram_recvmsg(sk, msg, len, nonblock, flags,
+ addr_len);
+
+ lock_sock(sk);
+ if (!skb_queue_empty(&sk->sk_receive_queue) &&
+ sk_psock_queue_empty(psock)) {
+ ret = __unix_dgram_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 = __unix_dgram_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;
+}
+
static struct proto *unix_prot_saved __read_mostly;
static DEFINE_SPINLOCK(unix_prot_lock);
static struct proto unix_bpf_prot;
@@ -13,6 +61,7 @@ static void unix_bpf_rebuild_protos(struct proto *prot, const struct proto *base
{
*prot = *base;
prot->close = sock_map_close;
+ prot->recvmsg = unix_dgram_bpf_recvmsg;
}
static void unix_bpf_check_needs_rebuild(struct proto *ops)
--
2.25.1
