linux-kernel - Re: [PATCH RFC net-next v4 4/8] vsock: make vsock bind reusable

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Message-ID: <ZJTTx0XJ2LeITNh0@bullseye>
Date:   Thu, 22 Jun 2023 23:05:43 +0000
From:   Bobby Eshleman <bobbyeshleman@...il.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
Cc:     Bobby Eshleman <bobby.eshleman@...edance.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Bryan Tan <bryantan@...are.com>,
        Vishnu Dasa <vdasa@...are.com>,
        VMware PV-Drivers Reviewers <pv-drivers@...are.com>,
        Dan Carpenter <dan.carpenter@...aro.org>,
        Simon Horman <simon.horman@...igine.com>,
        Krasnov Arseniy <oxffffaa@...il.com>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH RFC net-next v4 4/8] vsock: make vsock bind reusable

On Thu, Jun 22, 2023 at 05:25:55PM +0200, Stefano Garzarella wrote:
> On Sat, Jun 10, 2023 at 12:58:31AM +0000, Bobby Eshleman wrote:
> > This commit makes the bind table management functions in vsock usable
> > for different bind tables. For use by datagrams in a future patch.
> > 
> > Signed-off-by: Bobby Eshleman <bobby.eshleman@...edance.com>
> > ---
> > net/vmw_vsock/af_vsock.c | 33 ++++++++++++++++++++++++++-------
> > 1 file changed, 26 insertions(+), 7 deletions(-)
> > 
> > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > index ef86765f3765..7a3ca4270446 100644
> > --- a/net/vmw_vsock/af_vsock.c
> > +++ b/net/vmw_vsock/af_vsock.c
> > @@ -230,11 +230,12 @@ static void __vsock_remove_connected(struct vsock_sock *vsk)
> > 	sock_put(&vsk->sk);
> > }
> > 
> > -static struct sock *__vsock_find_bound_socket(struct sockaddr_vm *addr)
> > +struct sock *vsock_find_bound_socket_common(struct sockaddr_vm *addr,
> > +					    struct list_head *bind_table)
> > {
> > 	struct vsock_sock *vsk;
> > 
> > -	list_for_each_entry(vsk, vsock_bound_sockets(addr), bound_table) {
> > +	list_for_each_entry(vsk, bind_table, bound_table) {
> > 		if (vsock_addr_equals_addr(addr, &vsk->local_addr))
> > 			return sk_vsock(vsk);
> > 
> > @@ -247,6 +248,11 @@ static struct sock *__vsock_find_bound_socket(struct sockaddr_vm *addr)
> > 	return NULL;
> > }
> > 
> > +static struct sock *__vsock_find_bound_socket(struct sockaddr_vm *addr)
> > +{
> > +	return vsock_find_bound_socket_common(addr, vsock_bound_sockets(addr));
> > +}
> > +
> > static struct sock *__vsock_find_connected_socket(struct sockaddr_vm *src,
> > 						  struct sockaddr_vm *dst)
> > {
> > @@ -646,12 +652,17 @@ static void vsock_pending_work(struct work_struct *work)
> > 
> > /**** SOCKET OPERATIONS ****/
> > 
> > -static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > -				    struct sockaddr_vm *addr)
> > +static int vsock_bind_common(struct vsock_sock *vsk,
> > +			     struct sockaddr_vm *addr,
> > +			     struct list_head *bind_table,
> > +			     size_t table_size)
> > {
> > 	static u32 port;
> > 	struct sockaddr_vm new_addr;
> > 
> > +	if (table_size < VSOCK_HASH_SIZE)
> > +		return -1;
> 
> Why we need this check now?
> 

If the table_size is not at least VSOCK_HASH_SIZE then the
VSOCK_HASH(addr) used later could overflow the table.

Maybe this really deserves a WARN() and a comment?

> > +
> > 	if (!port)
> > 		port = get_random_u32_above(LAST_RESERVED_PORT);
> > 
> > @@ -667,7 +678,8 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > 
> > 			new_addr.svm_port = port++;
> > 
> > -			if (!__vsock_find_bound_socket(&new_addr)) {
> > +			if (!vsock_find_bound_socket_common(&new_addr,
> > +							    &bind_table[VSOCK_HASH(addr)])) {
> > 				found = true;
> > 				break;
> > 			}
> > @@ -684,7 +696,8 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > 			return -EACCES;
> > 		}
> > 
> > -		if (__vsock_find_bound_socket(&new_addr))
> > +		if (vsock_find_bound_socket_common(&new_addr,
> > +						   &bind_table[VSOCK_HASH(addr)]))
> > 			return -EADDRINUSE;
> > 	}
> > 
> > @@ -696,11 +709,17 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > 	 * by AF_UNIX.
> > 	 */
> > 	__vsock_remove_bound(vsk);
> > -	__vsock_insert_bound(vsock_bound_sockets(&vsk->local_addr), vsk);
> > +	__vsock_insert_bound(&bind_table[VSOCK_HASH(&vsk->local_addr)], vsk);
> > 
> > 	return 0;
> > }
> > 
> > +static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > +				    struct sockaddr_vm *addr)
> > +{
> > +	return vsock_bind_common(vsk, addr, vsock_bind_table, VSOCK_HASH_SIZE + 1);
> > +}
> > +
> > static int __vsock_bind_dgram(struct vsock_sock *vsk,
> > 			      struct sockaddr_vm *addr)
> > {
> > 
> > -- 
> > 2.30.2
> > 
> 
> The rest seems okay to me, but I agree with Simon's suggestion.
> 
> Stefano
> 

Thanks,
Bobby