Re: [PATCH RFC net-next v2 3/4] vsock: Add lockless sendmsg() support
From: Bobby Eshleman
Date: Fri Apr 28 2023 - 14:20:16 EST
On Fri, Apr 28, 2023 at 12:29:50PM +0200, Stefano Garzarella wrote:
> On Sat, Apr 15, 2023 at 10:30:55AM +0000, Bobby Eshleman wrote:
> > On Wed, Apr 19, 2023 at 11:30:53AM +0200, Stefano Garzarella wrote:
> > > On Fri, Apr 14, 2023 at 12:25:59AM +0000, Bobby Eshleman wrote:
> > > > Because the dgram sendmsg() path for AF_VSOCK acquires the socket lock
> > > > it does not scale when many senders share a socket.
> > > >
> > > > Prior to this patch the socket lock is used to protect the local_addr,
> > > > remote_addr, transport, and buffer size variables. What follows are the
> > > > new protection schemes for the various protected fields that ensure a
> > > > race-free multi-sender sendmsg() path for vsock dgrams.
> > > >
> > > > - local_addr
> > > > local_addr changes as a result of binding a socket. The write path
> > > > for local_addr is bind() and various vsock_auto_bind() call sites.
> > > > After a socket has been bound via vsock_auto_bind() or bind(), subsequent
> > > > calls to bind()/vsock_auto_bind() do not write to local_addr again. bind()
> > > > rejects the user request and vsock_auto_bind() early exits.
> > > > Therefore, the local addr can not change while a parallel thread is
> > > > in sendmsg() and lock-free reads of local addr in sendmsg() are safe.
> > > > Change: only acquire lock for auto-binding as-needed in sendmsg().
> > > >
> > > > - vsk->transport
> > > > Updated upon socket creation and it doesn't change again until the
> > >
> > > This is true only for dgram, right?
> > >
> >
> > Yes.
> >
> > > How do we decide which transport to assign for dgram?
> > >
> >
> > The transport is assigned in proto->create() [vsock_create()]. It is
> > assigned there *only* for dgrams, whereas for streams/seqpackets it is
> > assigned in connect(). vsock_create() sets transport to
> > 'transport_dgram' if sock->type == SOCK_DGRAM.
> >
> > vsock_sk_destruct() then eventually sets vsk->transport to NULL.
> >
> > Neither destruct nor create can occur in parallel with sendmsg().
> > create() hasn't yet returned the sockfd for the user to call upon it
> > sendmsg(), and AFAICT destruct is only called after the final socket
> > reference is released, which only happens after the socket no longer
> > exists in the fd lookup table and so sendmsg() will fail before it ever
> > has the chance to race.
>
> This is okay if a socket can be assigned to a single transport, but with
> dgrams I'm not sure we can do that.
>
> Since it is not connected, a socket can send or receive packets from
> different transports, so maybe we can't assign it to a specific one,
> but do a lookup for every packets to understand which transport to use.
>
Yes this is true, this lookup needs to be implemented... currently
sendmsg() doesn't do this at all. It grabs the remote_addr when passed
in from sendto(), but then just uses the same old transport from vsk.
You are right that sendto() should be a per-packet lookup, not a
vsk->transport read. Perhaps I should add that as another patch in this
series, and make it precede this one?
For the send() / sendto(NULL) case where vsk->transport is being read, I
do believe this is still race-free, but...
If we later support dynamic transports for datagram, such that
connect(VMADDR_LOCAL_CID) sets vsk->transport to transport_loopback,
connect(VMADDR_CID_HOST) sets vsk->transport to something like
transport_datagram_g2h, etc..., then vsk->transport will need to be
bundled into the RCU-protected pointer too, since it may change when
remote_addr changes.
> >
> > > > socket is destroyed, which only happens after the socket refcnt reaches
> > > > zero. This prevents any sendmsg() call from being entered because the
> > > > sockfd lookup fails beforehand. That is, sendmsg() and vsk->transport
> > > > writes cannot execute in parallel. Additionally, connect() doesn't
> > > > update vsk->transport for dgrams as it does for streams. Therefore
> > > > vsk->transport is also safe to access lock-free in the sendmsg() path.
> > > > No change.
> > > >
> > > > - buffer size variables
> > > > Not used by dgram, so they do not need protection. No change.
> > >
> > > Is this true because for dgram we use the socket buffer?
> > > Is it the same for VMCI?
> >
> > Yes. The buf_alloc derived from buffer_size is also always ignored after
> > being initialized once since credits aren't used.
> >
> > My reading of the VMCI code is that the buffer_size and
> > buffer_{min,max}_size variables are used only in connectible calls (like
> > connect and recv_listen), but not for datagrams.
>
> Okay, thanks for checking!
>
> >
> > >
> > > >
> > > > - remote_addr
> > > > Needs additional protection because before this patch the
> > > > remote_addr (consisting of several fields such as cid, port, and flags)
> > > > only changed atomically under socket lock context. By acquiring the
> > > > socket lock to read the structure, the changes made by connect() were
> > > > always made visible to sendmsg() atomically. Consequently, to retain
> > > > atomicity of updates but offer lock-free access, this patch
> > > > redesigns this field as an RCU-protected pointer.
> > > >
> > > > Writers are still synchronized using the socket lock, but readers
> > > > only read inside RCU read-side critical sections.
> > > >
> > > > Helpers are introduced for accessing and updating the new pointer.
> > > >
> > > > The remote_addr structure is wrapped together with an rcu_head into a
> > > > sockaddr_vm_rcu structure so that kfree_rcu() can be used. This removes
> > > > the need of writers to use synchronize_rcu() after freeing old structures
> > > > which is simply more efficient and reduces code churn where remote_addr
> > > > is already being updated inside read-side sections.
> > > >
> > > > Only virtio has been tested, but updates were necessary to the VMCI and
> > > > hyperv code. Unfortunately the author does not have access to
> > > > VMCI/hyperv systems so those changes are untested.
> > > >
> > > > Perf Tests
> > > > vCPUS: 16
> > > > Threads: 16
> > > > Payload: 4KB
> > > > Test Runs: 5
> > > > Type: SOCK_DGRAM
> > > >
> > > > Before: 245.2 MB/s
> > > > After: 509.2 MB/s (+107%)
> > > >
> > > > Notably, on the same test system, vsock dgram even outperforms
> > > > multi-threaded UDP over virtio-net with vhost and MQ support enabled.
> > >
> > > Cool!
> > >
> > > This patch is quite large, so I need to review it carefully in future
> > > versions, but in general it makes sense to me.
> > >
> > > Thanks,
> > > Stefano
> > >
> >
> > Thanks for the initial comments!
> >
> > Best,
> > Bobby
> >
> > > >
> > > > Throughput metrics for single-threaded SOCK_DGRAM and
> > > > single/multi-threaded SOCK_STREAM showed no statistically signficant
> > > > throughput changes (lowest p-value reaching 0.27), with the range of the
> > > > mean difference ranging between -5% to +1%.
> > > >
> > > > Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
> > > > ---
> > > > drivers/vhost/vsock.c | 12 +-
> > > > include/net/af_vsock.h | 19 ++-
> > > > net/vmw_vsock/af_vsock.c | 261 ++++++++++++++++++++++++++++----
> > > > net/vmw_vsock/diag.c | 10 +-
> > > > net/vmw_vsock/hyperv_transport.c | 15 +-
> > > > net/vmw_vsock/virtio_transport_common.c | 22 ++-
> > > > net/vmw_vsock/vmci_transport.c | 70 ++++++---
> > > > 7 files changed, 344 insertions(+), 65 deletions(-)
> > > >
> > > > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > > > index 028cf079225e..da105cb856ac 100644
> > > > --- a/drivers/vhost/vsock.c
> > > > +++ b/drivers/vhost/vsock.c
> > > > @@ -296,13 +296,17 @@ static int
> > > > vhost_transport_cancel_pkt(struct vsock_sock *vsk)
> > > > {
> > > > struct vhost_vsock *vsock;
> > > > + unsigned int cid;
> > > > int cnt = 0;
> > > > int ret = -ENODEV;
> > > >
> > > > rcu_read_lock();
> > > > + ret = vsock_remote_addr_cid(vsk, &cid);
> > > > + if (ret < 0)
> > > > + goto out;
> > > >
> > > > /* Find the vhost_vsock according to guest context id */
> > > > - vsock = vhost_vsock_get(vsk->remote_addr.svm_cid);
> > > > + vsock = vhost_vsock_get(cid);
> > > > if (!vsock)
> > > > goto out;
> > > >
> > > > @@ -686,6 +690,10 @@ static void vhost_vsock_flush(struct vhost_vsock *vsock)
> > > > static void vhost_vsock_reset_orphans(struct sock *sk)
> > > > {
> > > > struct vsock_sock *vsk = vsock_sk(sk);
> > > > + unsigned int cid;
> > > > +
> > > > + if (vsock_remote_addr_cid(vsk, &cid) < 0)
> > > > + return;
> > > >
> > > > /* vmci_transport.c doesn't take sk_lock here either. At least we're
> > > > * under vsock_table_lock so the sock cannot disappear while we're
> > > > @@ -693,7 +701,7 @@ static void vhost_vsock_reset_orphans(struct sock *sk)
> > > > */
> > > >
> > > > /* If the peer is still valid, no need to reset connection */
> > > > - if (vhost_vsock_get(vsk->remote_addr.svm_cid))
> > > > + if (vhost_vsock_get(cid))
> > > > return;
> > > >
> > > > /* If the close timeout is pending, let it expire. This avoids races
> > > > diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
> > > > index 57af28fede19..c02fd6ad0047 100644
> > > > --- a/include/net/af_vsock.h
> > > > +++ b/include/net/af_vsock.h
> > > > @@ -25,12 +25,17 @@ extern spinlock_t vsock_table_lock;
> > > > #define vsock_sk(__sk) ((struct vsock_sock *)__sk)
> > > > #define sk_vsock(__vsk) (&(__vsk)->sk)
> > > >
> > > > +struct sockaddr_vm_rcu {
> > > > + struct sockaddr_vm addr;
> > > > + struct rcu_head rcu;
> > > > +};
> > > > +
> > > > struct vsock_sock {
> > > > /* sk must be the first member. */
> > > > struct sock sk;
> > > > const struct vsock_transport *transport;
> > > > struct sockaddr_vm local_addr;
> > > > - struct sockaddr_vm remote_addr;
> > > > + struct sockaddr_vm_rcu * __rcu remote_addr;
> > > > /* Links for the global tables of bound and connected sockets. */
> > > > struct list_head bound_table;
> > > > struct list_head connected_table;
> > > > @@ -206,7 +211,7 @@ void vsock_release_pending(struct sock *pending);
> > > > void vsock_add_pending(struct sock *listener, struct sock *pending);
> > > > void vsock_remove_pending(struct sock *listener, struct sock *pending);
> > > > void vsock_enqueue_accept(struct sock *listener, struct sock *connected);
> > > > -void vsock_insert_connected(struct vsock_sock *vsk);
> > > > +int vsock_insert_connected(struct vsock_sock *vsk);
> > > > void vsock_remove_bound(struct vsock_sock *vsk);
> > > > void vsock_remove_connected(struct vsock_sock *vsk);
> > > > struct sock *vsock_find_bound_socket(struct sockaddr_vm *addr);
> > > > @@ -244,4 +249,14 @@ static inline void __init vsock_bpf_build_proto(void)
> > > > {}
> > > > #endif
> > > >
> > > > +/* RCU-protected remote addr helpers */
> > > > +int vsock_remote_addr_cid(struct vsock_sock *vsk, unsigned int *cid);
> > > > +int vsock_remote_addr_port(struct vsock_sock *vsk, unsigned int *port);
> > > > +int vsock_remote_addr_cid_port(struct vsock_sock *vsk, unsigned int *cid,
> > > > + unsigned int *port);
> > > > +int vsock_remote_addr_copy(struct vsock_sock *vsk, struct sockaddr_vm *dest);
> > > > +bool vsock_remote_addr_bound(struct vsock_sock *vsk);
> > > > +bool vsock_remote_addr_equals(struct vsock_sock *vsk, struct sockaddr_vm *other);
> > > > +int vsock_remote_addr_update_cid_port(struct vsock_sock *vsk, u32 cid, u32 port);
> > > > +
> > > > #endif /* __AF_VSOCK_H__ */
> > > > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > > > index 46b3f35e3adc..93b4abbf20b4 100644
> > > > --- a/net/vmw_vsock/af_vsock.c
> > > > +++ b/net/vmw_vsock/af_vsock.c
> > > > @@ -145,6 +145,139 @@ static const struct vsock_transport *transport_local;
> > > > static DEFINE_MUTEX(vsock_register_mutex);
> > > >
> > > > /**** UTILS ****/
> > > > +bool vsock_remote_addr_bound(struct vsock_sock *vsk)
> > > > +{
> > > > + struct sockaddr_vm_rcu *remote_addr;
> > > > + bool ret;
> > > > +
> > > > + rcu_read_lock();
> > > > + remote_addr = rcu_dereference(vsk->remote_addr);
> > > > + if (!remote_addr) {
> > > > + rcu_read_unlock();
> > > > + return false;
> > > > + }
> > > > +
> > > > + ret = vsock_addr_bound(&remote_addr->addr);
> > > > + rcu_read_unlock();
> > > > +
> > > > + return ret;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(vsock_remote_addr_bound);
> > > > +
> > > > +int vsock_remote_addr_copy(struct vsock_sock *vsk, struct sockaddr_vm *dest)
> > > > +{
> > > > + struct sockaddr_vm_rcu *remote_addr;
> > > > +
> > > > + rcu_read_lock();
> > > > + remote_addr = rcu_dereference(vsk->remote_addr);
> > > > + if (!remote_addr) {
> > > > + rcu_read_unlock();
> > > > + return -EINVAL;
> > > > + }
> > > > + memcpy(dest, &remote_addr->addr, sizeof(*dest));
> > > > + rcu_read_unlock();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(vsock_remote_addr_copy);
> > > > +
> > > > +int vsock_remote_addr_cid(struct vsock_sock *vsk, unsigned int *cid)
> > > > +{
> > > > + return vsock_remote_addr_cid_port(vsk, cid, NULL);
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(vsock_remote_addr_cid);
> > > > +
> > > > +int vsock_remote_addr_port(struct vsock_sock *vsk, unsigned int *port)
> > > > +{
> > > > + return vsock_remote_addr_cid_port(vsk, NULL, port);
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(vsock_remote_addr_port);
> > > > +
> > > > +int vsock_remote_addr_cid_port(struct vsock_sock *vsk, unsigned int *cid,
> > > > + unsigned int *port)
> > > > +{
> > > > + struct sockaddr_vm_rcu *remote_addr;
> > > > +
> > > > + rcu_read_lock();
> > > > + remote_addr = rcu_dereference(vsk->remote_addr);
> > > > + if (!remote_addr) {
> > > > + rcu_read_unlock();
> > > > + return -EINVAL;
> > > > + }
> > > > +
> > > > + if (cid)
> > > > + *cid = remote_addr->addr.svm_cid;
> > > > + if (port)
> > > > + *port = remote_addr->addr.svm_port;
> > > > +
> > > > + rcu_read_unlock();
> > > > + return 0;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(vsock_remote_addr_cid_port);
> > > > +
> > > > +/* The socket lock must be held by the caller */
> > > > +int vsock_remote_addr_update_cid_port(struct vsock_sock *vsk, u32 cid, u32 port)
> > > > +{
> > > > + struct sockaddr_vm_rcu *old, *new;
> > > > +
> > > > + new = kmalloc(sizeof(*new), GFP_KERNEL);
> > > > + if (!new)
> > > > + return -ENOMEM;
> > > > +
> > > > + rcu_read_lock();
> > > > + old = rcu_dereference(vsk->remote_addr);
> > > > + if (!old) {
> > > > + kfree(new);
> > > > + return -EINVAL;
> > > > + }
> > > > + memcpy(&new->addr, &old->addr, sizeof(new->addr));
> > > > + rcu_read_unlock();
> > > > +
> > > > + new->addr.svm_cid = cid;
> > > > + new->addr.svm_port = port;
> > > > +
> > > > + old = rcu_replace_pointer(vsk->remote_addr, new, lockdep_sock_is_held(sk_vsock(vsk)));
> > > > + kfree_rcu(old, rcu);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(vsock_remote_addr_update_cid_port);
> > > > +
> > > > +/* The socket lock must be held by the caller */
> > > > +int vsock_remote_addr_update(struct vsock_sock *vsk, struct sockaddr_vm *src)
> > > > +{
> > > > + struct sockaddr_vm_rcu *old, *new;
> > > > +
> > > > + new = kmalloc(sizeof(*new), GFP_KERNEL);
> > > > + if (!new)
> > > > + return -ENOMEM;
> > > > +
> > > > + memcpy(&new->addr, src, sizeof(new->addr));
> > > > + old = rcu_replace_pointer(vsk->remote_addr, new, lockdep_sock_is_held(sk_vsock(vsk)));
> > > > + kfree_rcu(old, rcu);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +bool vsock_remote_addr_equals(struct vsock_sock *vsk,
> > > > + struct sockaddr_vm *other)
> > > > +{
> > > > + struct sockaddr_vm_rcu *remote_addr;
> > > > + bool equals;
> > > > +
> > > > + rcu_read_lock();
> > > > + remote_addr = rcu_dereference(vsk->remote_addr);
> > > > + if (!remote_addr) {
> > > > + rcu_read_unlock();
> > > > + return false;
> > > > + }
> > > > +
> > > > + equals = vsock_addr_equals_addr(&remote_addr->addr, other);
> > > > + rcu_read_unlock();
> > > > +
> > > > + return equals;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(vsock_remote_addr_equals);
> > > >
> > > > /* Each bound VSocket is stored in the bind hash table and each connected
> > > > * VSocket is stored in the connected hash table.
> > > > @@ -254,10 +387,16 @@ static struct sock *__vsock_find_connected_socket(struct sockaddr_vm *src,
> > > >
> > > > list_for_each_entry(vsk, vsock_connected_sockets(src, dst),
> > > > connected_table) {
> > > > - if (vsock_addr_equals_addr(src, &vsk->remote_addr) &&
> > > > + struct sockaddr_vm_rcu *remote_addr;
> > > > +
> > > > + rcu_read_lock();
> > > > + remote_addr = rcu_dereference(vsk->remote_addr);
> > > > + if (vsock_addr_equals_addr(src, &remote_addr->addr) &&
> > > > dst->svm_port == vsk->local_addr.svm_port) {
> > > > + rcu_read_unlock();
> > > > return sk_vsock(vsk);
> > > > }
> > > > + rcu_read_unlock();
> > > > }
> > > >
> > > > return NULL;
> > > > @@ -270,14 +409,25 @@ static void vsock_insert_unbound(struct vsock_sock *vsk)
> > > > spin_unlock_bh(&vsock_table_lock);
> > > > }
> > > >
> > > > -void vsock_insert_connected(struct vsock_sock *vsk)
> > > > +int vsock_insert_connected(struct vsock_sock *vsk)
> > > > {
> > > > - struct list_head *list = vsock_connected_sockets(
> > > > - &vsk->remote_addr, &vsk->local_addr);
> > > > + struct list_head *list;
> > > > + struct sockaddr_vm_rcu *remote_addr;
> > > > +
> > > > + rcu_read_lock();
> > > > + remote_addr = rcu_dereference(vsk->remote_addr);
> > > > + if (!remote_addr) {
> > > > + rcu_read_unlock();
> > > > + return -EINVAL;
> > > > + }
> > > > + list = vsock_connected_sockets(&remote_addr->addr, &vsk->local_addr);
> > > > + rcu_read_unlock();
> > > >
> > > > spin_lock_bh(&vsock_table_lock);
> > > > __vsock_insert_connected(list, vsk);
> > > > spin_unlock_bh(&vsock_table_lock);
> > > > +
> > > > + return 0;
> > > > }
> > > > EXPORT_SYMBOL_GPL(vsock_insert_connected);
> > > >
> > > > @@ -438,10 +588,17 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
> > > > {
> > > > const struct vsock_transport *new_transport;
> > > > struct sock *sk = sk_vsock(vsk);
> > > > - unsigned int remote_cid = vsk->remote_addr.svm_cid;
> > > > + struct sockaddr_vm remote_addr;
> > > > + unsigned int remote_cid;
> > > > __u8 remote_flags;
> > > > int ret;
> > > >
> > > > + ret = vsock_remote_addr_copy(vsk, &remote_addr);
> > > > + if (ret < 0)
> > > > + return ret;
> > > > +
> > > > + remote_cid = remote_addr.svm_cid;
> > > > +
> > > > /* If the packet is coming with the source and destination CIDs higher
> > > > * than VMADDR_CID_HOST, then a vsock channel where all the packets are
> > > > * forwarded to the host should be established. Then the host will
> > > > @@ -451,10 +608,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
> > > > * the connect path the flag can be set by the user space application.
> > > > */
> > > > if (psk && vsk->local_addr.svm_cid > VMADDR_CID_HOST &&
> > > > - vsk->remote_addr.svm_cid > VMADDR_CID_HOST)
> > > > - vsk->remote_addr.svm_flags |= VMADDR_FLAG_TO_HOST;
> > > > + remote_addr.svm_cid > VMADDR_CID_HOST) {
> > > > + remote_addr.svm_flags |= VMADDR_CID_HOST;
> > > > +
> > > > + ret = vsock_remote_addr_update(vsk, &remote_addr);
> > > > + if (ret < 0)
> > > > + return ret;
> > > > + }
> > > >
> > > > - remote_flags = vsk->remote_addr.svm_flags;
> > > > + remote_flags = remote_addr.svm_flags;
> > > >
> > > > switch (sk->sk_type) {
> > > > case SOCK_DGRAM:
> > > > @@ -742,6 +904,7 @@ static struct sock *__vsock_create(struct net *net,
> > > > unsigned short type,
> > > > int kern)
> > > > {
> > > > + struct sockaddr_vm *remote_addr;
> > > > struct sock *sk;
> > > > struct vsock_sock *psk;
> > > > struct vsock_sock *vsk;
> > > > @@ -761,7 +924,14 @@ static struct sock *__vsock_create(struct net *net,
> > > >
> > > > vsk = vsock_sk(sk);
> > > > vsock_addr_init(&vsk->local_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
> > > > - vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
> > > > +
> > > > + remote_addr = kmalloc(sizeof(*remote_addr), GFP_KERNEL);
> > > > + if (!remote_addr) {
> > > > + sk_free(sk);
> > > > + return NULL;
> > > > + }
> > > > + vsock_addr_init(remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
> > > > + rcu_assign_pointer(vsk->remote_addr, remote_addr);
> > > >
> > > > sk->sk_destruct = vsock_sk_destruct;
> > > > sk->sk_backlog_rcv = vsock_queue_rcv_skb;
> > > > @@ -845,6 +1015,7 @@ static void __vsock_release(struct sock *sk, int level)
> > > > static void vsock_sk_destruct(struct sock *sk)
> > > > {
> > > > struct vsock_sock *vsk = vsock_sk(sk);
> > > > + struct sockaddr_vm_rcu *remote_addr;
> > > >
> > > > vsock_deassign_transport(vsk);
> > > >
> > > > @@ -852,8 +1023,8 @@ static void vsock_sk_destruct(struct sock *sk)
> > > > * possibly register the address family with the kernel.
> > > > */
> > > > vsock_addr_init(&vsk->local_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
> > > > - vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
> > > > -
> > > > + remote_addr = rcu_replace_pointer(vsk->remote_addr, NULL, 1);
> > > > + kfree_rcu(remote_addr);
> > > > put_cred(vsk->owner);
> > > > }
> > > >
> > > > @@ -943,6 +1114,7 @@ static int vsock_getname(struct socket *sock,
> > > > struct sock *sk;
> > > > struct vsock_sock *vsk;
> > > > struct sockaddr_vm *vm_addr;
> > > > + struct sockaddr_vm_rcu *rcu_ptr;
> > > >
> > > > sk = sock->sk;
> > > > vsk = vsock_sk(sk);
> > > > @@ -951,11 +1123,17 @@ static int vsock_getname(struct socket *sock,
> > > > lock_sock(sk);
> > > >
> > > > if (peer) {
> > > > + rcu_read_lock();
> > > > if (sock->state != SS_CONNECTED) {
> > > > err = -ENOTCONN;
> > > > goto out;
> > > > }
> > > > - vm_addr = &vsk->remote_addr;
> > > > + rcu_ptr = rcu_dereference(vsk->remote_addr);
> > > > + if (!rcu_ptr) {
> > > > + err = -EINVAL;
> > > > + goto out;
> > > > + }
> > > > + vm_addr = &rcu_ptr->addr;
> > > > } else {
> > > > vm_addr = &vsk->local_addr;
> > > > }
> > > > @@ -975,6 +1153,8 @@ static int vsock_getname(struct socket *sock,
> > > > err = sizeof(*vm_addr);
> > > >
> > > > out:
> > > > + if (peer)
> > > > + rcu_read_unlock();
> > > > release_sock(sk);
> > > > return err;
> > > > }
> > > > @@ -1161,7 +1341,7 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
> > > > int err;
> > > > struct sock *sk;
> > > > struct vsock_sock *vsk;
> > > > - struct sockaddr_vm *remote_addr;
> > > > + struct sockaddr_vm stack_addr, *remote_addr;
> > > > const struct vsock_transport *transport;
> > > >
> > > > if (msg->msg_flags & MSG_OOB)
> > > > @@ -1172,15 +1352,26 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
> > > > sk = sock->sk;
> > > > vsk = vsock_sk(sk);
> > > >
> > > > - lock_sock(sk);
> > > > + /* If auto-binding is required, acquire the slock to avoid potential
> > > > + * race conditions. Otherwise, do not acquire the lock.
> > > > + *
> > > > + * We know that the first check of local_addr is racy (indicated by
> > > > + * data_race()). By acquiring the lock and then subsequently checking
> > > > + * again if local_addr is bound (inside vsock_auto_bind()), we can
> > > > + * ensure there are no real data races.
> > > > + *
> > > > + * This technique is borrowed by inet_send_prepare().
> > > > + */
> > > > + if (data_race(!vsock_addr_bound(&vsk->local_addr))) {
> > > > + lock_sock(sk);
> > > > + err = vsock_auto_bind(vsk);
> > > > + release_sock(sk);
> > > > + if (err)
> > > > + return err;
> > > > + }
> > > >
> > > > transport = vsk->transport;
> > > >
> > > > - err = vsock_auto_bind(vsk);
> > > > - if (err)
> > > > - goto out;
> > > > -
> > > > -
> > > > /* If the provided message contains an address, use that. Otherwise
> > > > * fall back on the socket's remote handle (if it has been connected).
> > > > */
> > > > @@ -1199,18 +1390,26 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
> > > > goto out;
> > > > }
> > > > } else if (sock->state == SS_CONNECTED) {
> > > > - remote_addr = &vsk->remote_addr;
> > > > + err = vsock_remote_addr_copy(vsk, &stack_addr);
> > > > + if (err < 0)
> > > > + goto out;
> > > >
> > > > - if (remote_addr->svm_cid == VMADDR_CID_ANY)
> > > > - remote_addr->svm_cid = transport->get_local_cid();
> > > > + if (stack_addr.svm_cid == VMADDR_CID_ANY) {
> > > > + stack_addr.svm_cid = transport->get_local_cid();
> > > > + lock_sock(sk_vsock(vsk));
> > > > + vsock_remote_addr_update(vsk, &stack_addr);
> > > > + release_sock(sk_vsock(vsk));
> > > > + }
> > > >
> > > > /* XXX Should connect() or this function ensure remote_addr is
> > > > * bound?
> > > > */
> > > > - if (!vsock_addr_bound(&vsk->remote_addr)) {
> > > > + if (!vsock_addr_bound(&stack_addr)) {
> > > > err = -EINVAL;
> > > > goto out;
> > > > }
> > > > +
> > > > + remote_addr = &stack_addr;
> > > > } else {
> > > > err = -EINVAL;
> > > > goto out;
> > > > @@ -1225,7 +1424,6 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
> > > > err = transport->dgram_enqueue(vsk, remote_addr, msg, len);
> > > >
> > > > out:
> > > > - release_sock(sk);
> > > > return err;
> > > > }
> > > >
> > > > @@ -1243,8 +1441,7 @@ static int vsock_dgram_connect(struct socket *sock,
> > > > err = vsock_addr_cast(addr, addr_len, &remote_addr);
> > > > if (err == -EAFNOSUPPORT && remote_addr->svm_family == AF_UNSPEC) {
> > > > lock_sock(sk);
> > > > - vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY,
> > > > - VMADDR_PORT_ANY);
> > > > + vsock_remote_addr_update_cid_port(vsk, VMADDR_CID_ANY, VMADDR_PORT_ANY);
> > > > sock->state = SS_UNCONNECTED;
> > > > release_sock(sk);
> > > > return 0;
> > > > @@ -1263,7 +1460,10 @@ static int vsock_dgram_connect(struct socket *sock,
> > > > goto out;
> > > > }
> > > >
> > > > - memcpy(&vsk->remote_addr, remote_addr, sizeof(vsk->remote_addr));
> > > > + err = vsock_remote_addr_update(vsk, remote_addr);
> > > > + if (err < 0)
> > > > + goto out;
> > > > +
> > > > sock->state = SS_CONNECTED;
> > > >
> > > > /* sock map disallows redirection of non-TCP sockets with sk_state !=
> > > > @@ -1399,8 +1599,9 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr,
> > > > }
> > > >
> > > > /* Set the remote address that we are connecting to. */
> > > > - memcpy(&vsk->remote_addr, remote_addr,
> > > > - sizeof(vsk->remote_addr));
> > > > + err = vsock_remote_addr_update(vsk, remote_addr);
> > > > + if (err)
> > > > + goto out;
> > > >
> > > > err = vsock_assign_transport(vsk, NULL);
> > > > if (err)
> > > > @@ -1831,7 +2032,7 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> > > > goto out;
> > > > }
> > > >
> > > > - if (!vsock_addr_bound(&vsk->remote_addr)) {
> > > > + if (!vsock_remote_addr_bound(vsk)) {
> > > > err = -EDESTADDRREQ;
> > > > goto out;
> > > > }
> > > > diff --git a/net/vmw_vsock/diag.c b/net/vmw_vsock/diag.c
> > > > index a2823b1c5e28..f843bae86b32 100644
> > > > --- a/net/vmw_vsock/diag.c
> > > > +++ b/net/vmw_vsock/diag.c
> > > > @@ -15,8 +15,14 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
> > > > u32 portid, u32 seq, u32 flags)
> > > > {
> > > > struct vsock_sock *vsk = vsock_sk(sk);
> > > > + struct sockaddr_vm remote_addr;
> > > > struct vsock_diag_msg *rep;
> > > > struct nlmsghdr *nlh;
> > > > + int err;
> > > > +
> > > > + err = vsock_remote_addr_copy(vsk, &remote_addr);
> > > > + if (err < 0)
> > > > + return err;
> > > >
> > > > nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
> > > > flags);
> > > > @@ -36,8 +42,8 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
> > > > rep->vdiag_shutdown = sk->sk_shutdown;
> > > > rep->vdiag_src_cid = vsk->local_addr.svm_cid;
> > > > rep->vdiag_src_port = vsk->local_addr.svm_port;
> > > > - rep->vdiag_dst_cid = vsk->remote_addr.svm_cid;
> > > > - rep->vdiag_dst_port = vsk->remote_addr.svm_port;
> > > > + rep->vdiag_dst_cid = remote_addr.svm_cid;
> > > > + rep->vdiag_dst_port = remote_addr.svm_port;
> > > > rep->vdiag_ino = sock_i_ino(sk);
> > > >
> > > > sock_diag_save_cookie(sk, rep->vdiag_cookie);
> > > > diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
> > > > index 7cb1a9d2cdb4..462b2ec3e6e9 100644
> > > > --- a/net/vmw_vsock/hyperv_transport.c
> > > > +++ b/net/vmw_vsock/hyperv_transport.c
> > > > @@ -336,9 +336,11 @@ static void hvs_open_connection(struct vmbus_channel *chan)
> > > > hvs_addr_init(&vnew->local_addr, if_type);
> > > >
> > > > /* Remote peer is always the host */
> > > > - vsock_addr_init(&vnew->remote_addr,
> > > > - VMADDR_CID_HOST, VMADDR_PORT_ANY);
> > > > - vnew->remote_addr.svm_port = get_port_by_srv_id(if_instance);
> > > > + ret = vsock_remote_addr_update_cid_port(vnew, VMADDR_CID_HOST,
> > > > + get_port_by_srv_id(if_instance));
> > > > + if (ret < 0)
> > > > + goto out;
> > > > +
> > > > ret = vsock_assign_transport(vnew, vsock_sk(sk));
> > > > /* Transport assigned (looking at remote_addr) must be the
> > > > * same where we received the request.
> > > > @@ -459,13 +461,18 @@ static int hvs_connect(struct vsock_sock *vsk)
> > > > {
> > > > union hvs_service_id vm, host;
> > > > struct hvsock *h = vsk->trans;
> > > > + int err;
> > > >
> > > > vm.srv_id = srv_id_template;
> > > > vm.svm_port = vsk->local_addr.svm_port;
> > > > h->vm_srv_id = vm.srv_id;
> > > >
> > > > host.srv_id = srv_id_template;
> > > > - host.svm_port = vsk->remote_addr.svm_port;
> > > > +
> > > > + err = vsock_remote_addr_port(vsk, &host.svm_port);
> > > > + if (err < 0)
> > > > + return err;
> > > > +
> > > > h->host_srv_id = host.srv_id;
> > > >
> > > > return vmbus_send_tl_connect_request(&h->vm_srv_id, &h->host_srv_id);
> > > > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> > > > index 925acface893..1b87704e516a 100644
> > > > --- a/net/vmw_vsock/virtio_transport_common.c
> > > > +++ b/net/vmw_vsock/virtio_transport_common.c
> > > > @@ -258,8 +258,9 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
> > > > src_cid = t_ops->transport.get_local_cid();
> > > > src_port = vsk->local_addr.svm_port;
> > > > if (!info->remote_cid) {
> > > > - dst_cid = vsk->remote_addr.svm_cid;
> > > > - dst_port = vsk->remote_addr.svm_port;
> > > > + ret = vsock_remote_addr_cid_port(vsk, &dst_cid, &dst_port);
> > > > + if (ret < 0)
> > > > + return ret;
> > > > } else {
> > > > dst_cid = info->remote_cid;
> > > > dst_port = info->remote_port;
> > > > @@ -1169,7 +1170,9 @@ virtio_transport_recv_connecting(struct sock *sk,
> > > > case VIRTIO_VSOCK_OP_RESPONSE:
> > > > sk->sk_state = TCP_ESTABLISHED;
> > > > sk->sk_socket->state = SS_CONNECTED;
> > > > - vsock_insert_connected(vsk);
> > > > + err = vsock_insert_connected(vsk);
> > > > + if (err)
> > > > + goto destroy;
> > > > sk->sk_state_change(sk);
> > > > break;
> > > > case VIRTIO_VSOCK_OP_INVALID:
> > > > @@ -1403,9 +1406,8 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
> > > > vchild = vsock_sk(child);
> > > > vsock_addr_init(&vchild->local_addr, le64_to_cpu(hdr->dst_cid),
> > > > le32_to_cpu(hdr->dst_port));
> > > > - vsock_addr_init(&vchild->remote_addr, le64_to_cpu(hdr->src_cid),
> > > > - le32_to_cpu(hdr->src_port));
> > > > -
> > > > + vsock_remote_addr_update_cid_port(vchild, le64_to_cpu(hdr->src_cid),
> > > > + le32_to_cpu(hdr->src_port));
> > > > ret = vsock_assign_transport(vchild, vsk);
> > > > /* Transport assigned (looking at remote_addr) must be the same
> > > > * where we received the request.
> > > > @@ -1420,7 +1422,13 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
> > > > if (virtio_transport_space_update(child, skb))
> > > > child->sk_write_space(child);
> > > >
> > > > - vsock_insert_connected(vchild);
> > > > + ret = vsock_insert_connected(vchild);
> > > > + if (ret) {
> > > > + release_sock(child);
> > > > + virtio_transport_reset_no_sock(t, skb);
> > > > + sock_put(child);
> > > > + return ret;
> > > > + }
> > > > vsock_enqueue_accept(sk, child);
> > > > virtio_transport_send_response(vchild, skb);
> > > >
> > > > diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
> > > > index b370070194fa..c0c445e7d925 100644
> > > > --- a/net/vmw_vsock/vmci_transport.c
> > > > +++ b/net/vmw_vsock/vmci_transport.c
> > > > @@ -283,18 +283,25 @@ vmci_transport_send_control_pkt(struct sock *sk,
> > > > u16 proto,
> > > > struct vmci_handle handle)
> > > > {
> > > > + struct sockaddr_vm addr_stack;
> > > > + struct sockaddr_vm *remote_addr = &addr_stack;
> > > > struct vsock_sock *vsk;
> > > > + int err;
> > > >
> > > > vsk = vsock_sk(sk);
> > > >
> > > > if (!vsock_addr_bound(&vsk->local_addr))
> > > > return -EINVAL;
> > > >
> > > > - if (!vsock_addr_bound(&vsk->remote_addr))
> > > > + if (!vsock_remote_addr_bound(vsk))
> > > > return -EINVAL;
> > > >
> > > > + err = vsock_remote_addr_copy(vsk, &addr_stack);
> > > > + if (err < 0)
> > > > + return err;
> > > > +
> > > > return vmci_transport_alloc_send_control_pkt(&vsk->local_addr,
> > > > - &vsk->remote_addr,
> > > > + remote_addr,
> > > > type, size, mode,
> > > > wait, proto, handle);
> > > > }
> > > > @@ -317,6 +324,7 @@ static int vmci_transport_send_reset(struct sock *sk,
> > > > struct sockaddr_vm *dst_ptr;
> > > > struct sockaddr_vm dst;
> > > > struct vsock_sock *vsk;
> > > > + int err;
> > > >
> > > > if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST)
> > > > return 0;
> > > > @@ -326,13 +334,16 @@ static int vmci_transport_send_reset(struct sock *sk,
> > > > if (!vsock_addr_bound(&vsk->local_addr))
> > > > return -EINVAL;
> > > >
> > > > - if (vsock_addr_bound(&vsk->remote_addr)) {
> > > > - dst_ptr = &vsk->remote_addr;
> > > > + if (vsock_remote_addr_bound(vsk)) {
> > > > + err = vsock_remote_addr_copy(vsk, &dst);
> > > > + if (err < 0)
> > > > + return err;
> > > > } else {
> > > > vsock_addr_init(&dst, pkt->dg.src.context,
> > > > pkt->src_port);
> > > > - dst_ptr = &dst;
> > > > }
> > > > + dst_ptr = &dst;
> > > > +
> > > > return vmci_transport_alloc_send_control_pkt(&vsk->local_addr, dst_ptr,
> > > > VMCI_TRANSPORT_PACKET_TYPE_RST,
> > > > 0, 0, NULL, VSOCK_PROTO_INVALID,
> > > > @@ -490,7 +501,7 @@ static struct sock *vmci_transport_get_pending(
> > > >
> > > > list_for_each_entry(vpending, &vlistener->pending_links,
> > > > pending_links) {
> > > > - if (vsock_addr_equals_addr(&src, &vpending->remote_addr) &&
> > > > + if (vsock_remote_addr_equals(vpending, &src) &&
> > > > pkt->dst_port == vpending->local_addr.svm_port) {
> > > > pending = sk_vsock(vpending);
> > > > sock_hold(pending);
> > > > @@ -1015,8 +1026,8 @@ static int vmci_transport_recv_listen(struct sock *sk,
> > > >
> > > > vsock_addr_init(&vpending->local_addr, pkt->dg.dst.context,
> > > > pkt->dst_port);
> > > > - vsock_addr_init(&vpending->remote_addr, pkt->dg.src.context,
> > > > - pkt->src_port);
> > > > + vsock_remote_addr_update_cid_port(vpending, pkt->dg.src.context,
> > > > + pkt->src_port);
> > > >
> > > > err = vsock_assign_transport(vpending, vsock_sk(sk));
> > > > /* Transport assigned (looking at remote_addr) must be the same
> > > > @@ -1133,6 +1144,7 @@ vmci_transport_recv_connecting_server(struct sock *listener,
> > > > {
> > > > struct vsock_sock *vpending;
> > > > struct vmci_handle handle;
> > > > + unsigned int vpending_remote_cid;
> > > > struct vmci_qp *qpair;
> > > > bool is_local;
> > > > u32 flags;
> > > > @@ -1189,8 +1201,13 @@ vmci_transport_recv_connecting_server(struct sock *listener,
> > > > /* vpending->local_addr always has a context id so we do not need to
> > > > * worry about VMADDR_CID_ANY in this case.
> > > > */
> > > > - is_local =
> > > > - vpending->remote_addr.svm_cid == vpending->local_addr.svm_cid;
> > > > + err = vsock_remote_addr_cid(vpending, &vpending_remote_cid);
> > > > + if (err < 0) {
> > > > + skerr = EPROTO;
> > > > + goto destroy;
> > > > + }
> > > > +
> > > > + is_local = vpending_remote_cid == vpending->local_addr.svm_cid;
> > > > flags = VMCI_QPFLAG_ATTACH_ONLY;
> > > > flags |= is_local ? VMCI_QPFLAG_LOCAL : 0;
> > > >
> > > > @@ -1203,7 +1220,7 @@ vmci_transport_recv_connecting_server(struct sock *listener,
> > > > flags,
> > > > vmci_transport_is_trusted(
> > > > vpending,
> > > > - vpending->remote_addr.svm_cid));
> > > > + vpending_remote_cid));
> > > > if (err < 0) {
> > > > vmci_transport_send_reset(pending, pkt);
> > > > skerr = -err;
> > > > @@ -1306,9 +1323,20 @@ vmci_transport_recv_connecting_client(struct sock *sk,
> > > > break;
> > > > case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE:
> > > > case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2:
> > > > + struct sockaddr_vm_rcu *remote_addr;
> > > > +
> > > > + rcu_read_lock();
> > > > + remote_addr = rcu_dereference(vsk->remote_addr);
> > > > + if (!remote_addr) {
> > > > + skerr = EPROTO;
> > > > + err = -EINVAL;
> > > > + rcu_read_unlock();
> > > > + goto destroy;
> > > > + }
> > > > +
> > > > if (pkt->u.size == 0
> > > > - || pkt->dg.src.context != vsk->remote_addr.svm_cid
> > > > - || pkt->src_port != vsk->remote_addr.svm_port
> > > > + || pkt->dg.src.context != remote_addr->addr.svm_cid
> > > > + || pkt->src_port != remote_addr->addr.svm_port
> > > > || !vmci_handle_is_invalid(vmci_trans(vsk)->qp_handle)
> > > > || vmci_trans(vsk)->qpair
> > > > || vmci_trans(vsk)->produce_size != 0
> > > > @@ -1316,9 +1344,10 @@ vmci_transport_recv_connecting_client(struct sock *sk,
> > > > || vmci_trans(vsk)->detach_sub_id != VMCI_INVALID_ID) {
> > > > skerr = EPROTO;
> > > > err = -EINVAL;
> > > > -
> > > > + rcu_read_unlock();
> > > > goto destroy;
> > > > }
> > > > + rcu_read_unlock();
> > > >
> > > > err = vmci_transport_recv_connecting_client_negotiate(sk, pkt);
> > > > if (err) {
> > > > @@ -1379,6 +1408,7 @@ static int vmci_transport_recv_connecting_client_negotiate(
> > > > int err;
> > > > struct vsock_sock *vsk;
> > > > struct vmci_handle handle;
> > > > + unsigned int remote_cid;
> > > > struct vmci_qp *qpair;
> > > > u32 detach_sub_id;
> > > > bool is_local;
> > > > @@ -1449,19 +1479,23 @@ static int vmci_transport_recv_connecting_client_negotiate(
> > > >
> > > > /* Make VMCI select the handle for us. */
> > > > handle = VMCI_INVALID_HANDLE;
> > > > - is_local = vsk->remote_addr.svm_cid == vsk->local_addr.svm_cid;
> > > > +
> > > > + err = vsock_remote_addr_cid(vsk, &remote_cid);
> > > > + if (err < 0)
> > > > + goto destroy;
> > > > +
> > > > + is_local = remote_cid == vsk->local_addr.svm_cid;
> > > > flags = is_local ? VMCI_QPFLAG_LOCAL : 0;
> > > >
> > > > err = vmci_transport_queue_pair_alloc(&qpair,
> > > > &handle,
> > > > pkt->u.size,
> > > > pkt->u.size,
> > > > - vsk->remote_addr.svm_cid,
> > > > + remote_cid,
> > > > flags,
> > > > vmci_transport_is_trusted(
> > > > vsk,
> > > > - vsk->
> > > > - remote_addr.svm_cid));
> > > > + remote_cid));
> > > > if (err < 0)
> > > > goto destroy;
> > > >
> > > >
> > > > --
> > > > 2.30.2
> > > >
> > >
> >
>
>
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