[PATCH bpf-next v6 2/5] af_unix: add unix_stream_proto for sockmap

From: Jiang Wang
Date: Sat Aug 14 2021 - 00:28:28 EST

Previously, sockmap for AF_UNIX protocol only supports
dgram type. This patch add unix stream type support, which
is similar to unix_dgram_proto. To support sockmap, dgram
and stream cannot share the same unix_proto anymore, because
they have different implementations, such as unhash for stream
type (which will remove closed or disconnected sockets from the map),
so rename unix_proto to unix_dgram_proto and add a new
unix_stream_proto.

Also implement stream related sockmap functions.
And add dgram key words to those dgram specific functions.

Signed-off-by: Jiang Wang <jiang.wang@xxxxxxxxxxxxx>
Reviewed-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
---
include/net/af_unix.h | 8 +++-
net/unix/af_unix.c | 83 ++++++++++++++++++++++++++++++++------
net/unix/unix_bpf.c | 93 +++++++++++++++++++++++++++++++++----------
3 files changed, 147 insertions(+), 37 deletions(-)

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 4757d7f53f13..7d142e8a0550 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -87,6 +87,8 @@ long unix_outq_len(struct sock *sk);

int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
int flags);
+int __unix_stream_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
+ int flags);
#ifdef CONFIG_SYSCTL
int unix_sysctl_register(struct net *net);
void unix_sysctl_unregister(struct net *net);
@@ -96,9 +98,11 @@ static inline void unix_sysctl_unregister(struct net *net) {}
#endif

#ifdef CONFIG_BPF_SYSCALL
-extern struct proto unix_proto;
+extern struct proto unix_dgram_proto;
+extern struct proto unix_stream_proto;

-int unix_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
+int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
+int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
void __init unix_bpf_build_proto(void);
#else
static inline void __init unix_bpf_build_proto(void)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 31061304ccf2..e7da96c80c71 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -797,17 +797,35 @@ static void unix_close(struct sock *sk, long timeout)
*/
}

-struct proto unix_proto = {
- .name = "UNIX",
+static void unix_unhash(struct sock *sk)
+{
+ /* Nothing to do here, unix socket does not need a ->unhash().
+ * This is merely for sockmap.
+ */
+}
+
+struct proto unix_dgram_proto = {
+ .name = "UNIX-DGRAM",
+ .owner = THIS_MODULE,
+ .obj_size = sizeof(struct unix_sock),
+ .close = unix_close,
+#ifdef CONFIG_BPF_SYSCALL
+ .psock_update_sk_prot = unix_dgram_bpf_update_proto,
+#endif
+};
+
+struct proto unix_stream_proto = {
+ .name = "UNIX-STREAM",
.owner = THIS_MODULE,
.obj_size = sizeof(struct unix_sock),
.close = unix_close,
+ .unhash = unix_unhash,
#ifdef CONFIG_BPF_SYSCALL
- .psock_update_sk_prot = unix_bpf_update_proto,
+ .psock_update_sk_prot = unix_stream_bpf_update_proto,
#endif
};

-static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
+static struct sock *unix_create1(struct net *net, struct socket *sock, int kern, int type)
{
struct sock *sk = NULL;
struct unix_sock *u;
@@ -816,7 +834,11 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files())
goto out;

- sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto, kern);
+ if (type == SOCK_STREAM)
+ sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_stream_proto, kern);
+ else /*dgram and seqpacket */
+ sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_dgram_proto, kern);
+
if (!sk)
goto out;

@@ -878,7 +900,7 @@ static int unix_create(struct net *net, struct socket *sock, int protocol,
return -ESOCKTNOSUPPORT;
}

- return unix_create1(net, sock, kern) ? 0 : -ENOMEM;
+ return unix_create1(net, sock, kern, sock->type) ? 0 : -ENOMEM;
}

static int unix_release(struct socket *sock)
@@ -1292,7 +1314,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
err = -ENOMEM;

/* create new sock for complete connection */
- newsk = unix_create1(sock_net(sk), NULL, 0);
+ newsk = unix_create1(sock_net(sk), NULL, 0, sock->type);
if (newsk == NULL)
goto out;

@@ -2322,8 +2344,10 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, size_t si
struct sock *sk = sock->sk;

#ifdef CONFIG_BPF_SYSCALL
- if (sk->sk_prot != &unix_proto)
- return sk->sk_prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT,
+ const struct proto *prot = READ_ONCE(sk->sk_prot);
+
+ if (prot != &unix_dgram_proto)
+ return prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT,
flags & ~MSG_DONTWAIT, NULL);
#endif
return __unix_dgram_recvmsg(sk, msg, size, flags);
@@ -2727,6 +2751,20 @@ static int unix_stream_read_actor(struct sk_buff *skb,
return ret ?: chunk;
}

+int __unix_stream_recvmsg(struct sock *sk, struct msghdr *msg,
+ size_t size, int flags)
+{
+ struct unix_stream_read_state state = {
+ .recv_actor = unix_stream_read_actor,
+ .socket = sk->sk_socket,
+ .msg = msg,
+ .size = size,
+ .flags = flags
+ };
+
+ return unix_stream_read_generic(&state, true);
+}
+
static int unix_stream_recvmsg(struct socket *sock, struct msghdr *msg,
size_t size, int flags)
{
@@ -2738,6 +2776,14 @@ static int unix_stream_recvmsg(struct socket *sock, struct msghdr *msg,
.flags = flags
};

+#ifdef CONFIG_BPF_SYSCALL
+ struct sock *sk = sock->sk;
+ const struct proto *prot = READ_ONCE(sk->sk_prot);
+
+ if (prot != &unix_stream_proto)
+ return prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT,
+ flags & ~MSG_DONTWAIT, NULL);
+#endif
return unix_stream_read_generic(&state, true);
}

@@ -2798,7 +2844,9 @@ static int unix_shutdown(struct socket *sock, int mode)
(sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)) {

int peer_mode = 0;
+ const struct proto *prot = READ_ONCE(other->sk_prot);

+ prot->unhash(other);
if (mode&RCV_SHUTDOWN)
peer_mode |= SEND_SHUTDOWN;
if (mode&SEND_SHUTDOWN)
@@ -2807,10 +2855,12 @@ static int unix_shutdown(struct socket *sock, int mode)
other->sk_shutdown |= peer_mode;
unix_state_unlock(other);
other->sk_state_change(other);
- if (peer_mode == SHUTDOWN_MASK)
+ if (peer_mode == SHUTDOWN_MASK) {
sk_wake_async(other, SOCK_WAKE_WAITD, POLL_HUP);
- else if (peer_mode & RCV_SHUTDOWN)
+ other->sk_state = TCP_CLOSE;
+ } else if (peer_mode & RCV_SHUTDOWN) {
sk_wake_async(other, SOCK_WAKE_WAITD, POLL_IN);
+ }
}
if (other)
sock_put(other);
@@ -3201,7 +3251,13 @@ static int __init af_unix_init(void)

BUILD_BUG_ON(sizeof(struct unix_skb_parms) > sizeof_field(struct sk_buff, cb));

- rc = proto_register(&unix_proto, 1);
+ rc = proto_register(&unix_dgram_proto, 1);
+ if (rc != 0) {
+ pr_crit("%s: Cannot create unix_sock SLAB cache!\n", __func__);
+ goto out;
+ }
+
+ rc = proto_register(&unix_stream_proto, 1);
if (rc != 0) {
pr_crit("%s: Cannot create unix_sock SLAB cache!\n", __func__);
goto out;
@@ -3217,7 +3273,8 @@ static int __init af_unix_init(void)
static void __exit af_unix_exit(void)
{
sock_unregister(PF_UNIX);
- proto_unregister(&unix_proto);
+ proto_unregister(&unix_dgram_proto);
+ proto_unregister(&unix_stream_proto);
unregister_pernet_subsys(&unix_net_ops);
}

diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
index 20f53575b5c9..b927e2baae50 100644
--- a/net/unix/unix_bpf.c
+++ b/net/unix/unix_bpf.c
@@ -38,9 +38,18 @@ static int unix_msg_wait_data(struct sock *sk, struct sk_psock *psock,
return ret;
}

-static int unix_dgram_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
- size_t len, int nonblock, int flags,
- int *addr_len)
+static int __unix_recvmsg(struct sock *sk, struct msghdr *msg,
+ size_t len, int flags)
+{
+ if (sk->sk_type == SOCK_DGRAM)
+ return __unix_dgram_recvmsg(sk, msg, len, flags);
+ else
+ return __unix_stream_recvmsg(sk, msg, len, flags);
+}
+
+static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
+ size_t len, int nonblock, int flags,
+ int *addr_len)
{
struct unix_sock *u = unix_sk(sk);
struct sk_psock *psock;
@@ -48,14 +57,14 @@ static int unix_dgram_bpf_recvmsg(struct sock *sk, struct msghdr *msg,

psock = sk_psock_get(sk);
if (unlikely(!psock))
- return __unix_dgram_recvmsg(sk, msg, len, flags);
+ return __unix_recvmsg(sk, msg, len, flags);

mutex_lock(&u->iolock);
if (!skb_queue_empty(&sk->sk_receive_queue) &&
sk_psock_queue_empty(psock)) {
mutex_unlock(&u->iolock);
sk_psock_put(sk, psock);
- return __unix_dgram_recvmsg(sk, msg, len, flags);
+ return __unix_recvmsg(sk, msg, len, flags);
}

msg_bytes_ready:
@@ -71,7 +80,7 @@ static int unix_dgram_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
goto msg_bytes_ready;
mutex_unlock(&u->iolock);
sk_psock_put(sk, psock);
- return __unix_dgram_recvmsg(sk, msg, len, flags);
+ return __unix_recvmsg(sk, msg, len, flags);
}
copied = -EAGAIN;
}
@@ -80,30 +89,55 @@ static int unix_dgram_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
return copied;
}

-static struct proto *unix_prot_saved __read_mostly;
-static DEFINE_SPINLOCK(unix_prot_lock);
-static struct proto unix_bpf_prot;
+static struct proto *unix_dgram_prot_saved __read_mostly;
+static DEFINE_SPINLOCK(unix_dgram_prot_lock);
+static struct proto unix_dgram_bpf_prot;
+
+static struct proto *unix_stream_prot_saved __read_mostly;
+static DEFINE_SPINLOCK(unix_stream_prot_lock);
+static struct proto unix_stream_bpf_prot;

-static void unix_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
+static void unix_dgram_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
{
*prot = *base;
prot->close = sock_map_close;
- prot->recvmsg = unix_dgram_bpf_recvmsg;
+ prot->recvmsg = unix_bpf_recvmsg;
+}
+
+static void unix_stream_bpf_rebuild_protos(struct proto *prot,
+ const struct proto *base)
+{
+ *prot = *base;
+ prot->close = sock_map_close;
+ prot->recvmsg = unix_bpf_recvmsg;
+ prot->unhash = sock_map_unhash;
+}
+
+static void unix_dgram_bpf_check_needs_rebuild(struct proto *ops)
+{
+ if (unlikely(ops != smp_load_acquire(&unix_dgram_prot_saved))) {
+ spin_lock_bh(&unix_dgram_prot_lock);
+ if (likely(ops != unix_dgram_prot_saved)) {
+ unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, ops);
+ smp_store_release(&unix_dgram_prot_saved, ops);
+ }
+ spin_unlock_bh(&unix_dgram_prot_lock);
+ }
}

-static void unix_bpf_check_needs_rebuild(struct proto *ops)
+static void unix_stream_bpf_check_needs_rebuild(struct proto *ops)
{
- if (unlikely(ops != smp_load_acquire(&unix_prot_saved))) {
- spin_lock_bh(&unix_prot_lock);
- if (likely(ops != unix_prot_saved)) {
- unix_bpf_rebuild_protos(&unix_bpf_prot, ops);
- smp_store_release(&unix_prot_saved, ops);
+ if (unlikely(ops != smp_load_acquire(&unix_stream_prot_saved))) {
+ spin_lock_bh(&unix_stream_prot_lock);
+ if (likely(ops != unix_stream_prot_saved)) {
+ unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, ops);
+ smp_store_release(&unix_stream_prot_saved, ops);
}
- spin_unlock_bh(&unix_prot_lock);
+ spin_unlock_bh(&unix_stream_prot_lock);
}
}

-int unix_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
+int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
{
if (sk->sk_type != SOCK_DGRAM)
return -EOPNOTSUPP;
@@ -114,12 +148,27 @@ int unix_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
return 0;
}

- unix_bpf_check_needs_rebuild(psock->sk_proto);
- WRITE_ONCE(sk->sk_prot, &unix_bpf_prot);
+ unix_dgram_bpf_check_needs_rebuild(psock->sk_proto);
+ WRITE_ONCE(sk->sk_prot, &unix_dgram_bpf_prot);
+ return 0;
+}
+
+int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
+{
+ if (restore) {
+ sk->sk_write_space = psock->saved_write_space;
+ WRITE_ONCE(sk->sk_prot, psock->sk_proto);
+ return 0;
+ }
+
+ unix_stream_bpf_check_needs_rebuild(psock->sk_proto);
+ WRITE_ONCE(sk->sk_prot, &unix_stream_bpf_prot);
return 0;
}

void __init unix_bpf_build_proto(void)
{
- unix_bpf_rebuild_protos(&unix_bpf_prot, &unix_proto);
+ unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, &unix_dgram_proto);
+ unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, &unix_stream_proto);
+
}
--
2.20.1