Date: Tue, 19 Sep 2023 10:13:07 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Jordan Rife <jrife@...gle.com>, 
 davem@...emloft.net, 
 edumazet@...gle.com, 
 kuba@...nel.org, 
 pabeni@...hat.com, 
 willemdebruijn.kernel@...il.com, 
 netdev@...r.kernel.org
Cc: dborkman@...nel.org, 
 philipp.reisner@...bit.com, 
 lars.ellenberg@...bit.com, 
 christoph.boehmwalder@...bit.com, 
 axboe@...nel.dk, 
 airlied@...hat.com, 
 chengyou@...ux.alibaba.com, 
 kaishen@...ux.alibaba.com, 
 jgg@...pe.ca, 
 leon@...nel.org, 
 bmt@...ich.ibm.com, 
 isdn@...ux-pingi.de, 
 ccaulfie@...hat.com, 
 teigland@...hat.com, 
 mark@...heh.com, 
 jlbec@...lplan.org, 
 joseph.qi@...ux.alibaba.com, 
 sfrench@...ba.org, 
 pc@...guebit.com, 
 lsahlber@...hat.com, 
 sprasad@...rosoft.com, 
 tom@...pey.com, 
 horms@...ge.net.au, 
 ja@....bg, 
 pablo@...filter.org, 
 kadlec@...filter.org, 
 fw@...len.de, 
 santosh.shilimkar@...cle.com, 
 Jordan Rife <jrife@...gle.com>
Subject: Re: [PATCH net v3 3/3] net: prevent address rewrite in kernel_bind()

Jordan Rife wrote:
> Similar to the change in commit 0bdf399342c5("net: Avoid address
> overwrite in kernel_connect"), BPF hooks run on bind may rewrite the
> address passed to kernel_bind(). This change
> 
> 1) Makes a copy of the bind address in kernel_bind() to insulate
>    callers.
> 2) Replaces direct calls to sock->ops->bind() with kernel_bind()
> 
> Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
> Fixes: 4fbac77d2d09 ("bpf: Hooks for sys_bind")
> Signed-off-by: Jordan Rife <jrife@...gle.com>
> ---
> v2->v3: Add "Fixes" tag. Check for positivity in addrlen sanity check.
> v1->v2: Split up original patch into patch series. Insulate
> 	sock->ops->bind() calls with kernel_bind().
> 
>  drivers/block/drbd/drbd_receiver.c     |  4 ++--
>  drivers/char/agp/alpha-agp.c           |  2 +-
>  drivers/infiniband/hw/erdma/erdma_cm.c |  6 +++---
>  drivers/infiniband/sw/siw/siw_cm.c     | 10 +++++-----
>  drivers/isdn/mISDN/l1oip_core.c        |  4 ++--
>  fs/dlm/lowcomms.c                      |  7 +++----
>  fs/ocfs2/cluster/tcp.c                 |  6 +++---
>  fs/smb/client/connect.c                |  6 +++---
>  net/netfilter/ipvs/ip_vs_sync.c        |  4 ++--
>  net/rds/tcp_connect.c                  |  2 +-
>  net/rds/tcp_listen.c                   |  2 +-
>  net/socket.c                           |  7 +++++++
>  12 files changed, 33 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
> index 9b2660e990a98..752759ed22b8c 100644
> --- a/drivers/block/drbd/drbd_receiver.c
> +++ b/drivers/block/drbd/drbd_receiver.c
> @@ -638,7 +638,7 @@ static struct socket *drbd_try_connect(struct drbd_connection *connection)
>  	*  a free one dynamically.
>  	*/
>  	what = "bind before connect";
> -	err = sock->ops->bind(sock, (struct sockaddr *) &src_in6, my_addr_len);
> +	err = kernel_bind(sock, (struct sockaddr *)&src_in6, my_addr_len);
>  	if (err < 0)
>  		goto out;
>  
> @@ -725,7 +725,7 @@ static int prepare_listen_socket(struct drbd_connection *connection, struct acce
>  	drbd_setbufsize(s_listen, sndbuf_size, rcvbuf_size);
>  
>  	what = "bind before listen";
> -	err = s_listen->ops->bind(s_listen, (struct sockaddr *)&my_addr, my_addr_len);
> +	err = kernel_bind(s_listen, (struct sockaddr *)&my_addr, my_addr_len);
>  	if (err < 0)
>  		goto out;
>  
> diff --git a/drivers/char/agp/alpha-agp.c b/drivers/char/agp/alpha-agp.c
> index c9bf2c2198418..f251fedfb4840 100644
> --- a/drivers/char/agp/alpha-agp.c
> +++ b/drivers/char/agp/alpha-agp.c
> @@ -96,7 +96,7 @@ static int alpha_core_agp_insert_memory(struct agp_memory *mem, off_t pg_start,
>  	if ((pg_start + mem->page_count) > num_entries)
>  		return -EINVAL;
>  
> -	status = agp->ops->bind(agp, pg_start, mem);
> +	status = kernel_bind(agp, pg_start, mem);
>  	mb();
>  	alpha_core_agp_tlbflush(mem);
>  
> diff --git a/drivers/infiniband/hw/erdma/erdma_cm.c b/drivers/infiniband/hw/erdma/erdma_cm.c
> index e2b89e7bbe2b8..674702d159c29 100644
> --- a/drivers/infiniband/hw/erdma/erdma_cm.c
> +++ b/drivers/infiniband/hw/erdma/erdma_cm.c
> @@ -990,7 +990,7 @@ static int kernel_bindconnect(struct socket *s, struct sockaddr *laddr,
>  	int ret;
>  
>  	sock_set_reuseaddr(s->sk);
> -	ret = s->ops->bind(s, laddr, laddrlen);
> +	ret = kernel_bind(s, laddr, laddrlen);
>  	if (ret)
>  		return ret;
>  	ret = kernel_connect(s, raddr, raddrlen, flags);
> @@ -1309,8 +1309,8 @@ int erdma_create_listen(struct iw_cm_id *id, int backlog)
>  	if (ipv4_is_zeronet(laddr->sin_addr.s_addr))
>  		s->sk->sk_bound_dev_if = dev->netdev->ifindex;
>  
> -	ret = s->ops->bind(s, (struct sockaddr *)laddr,
> -			   sizeof(struct sockaddr_in));
> +	ret = kernel_bind(s, (struct sockaddr *)laddr,
> +			  sizeof(struct sockaddr_in));
>  	if (ret)
>  		goto error;
>  
> diff --git a/drivers/infiniband/sw/siw/siw_cm.c b/drivers/infiniband/sw/siw/siw_cm.c
> index 05624f424153e..d05e0eeee9244 100644
> --- a/drivers/infiniband/sw/siw/siw_cm.c
> +++ b/drivers/infiniband/sw/siw/siw_cm.c
> @@ -1324,7 +1324,7 @@ static int kernel_bindconnect(struct socket *s, struct sockaddr *laddr,
>  			return rv;
>  	}
>  
> -	rv = s->ops->bind(s, laddr, size);
> +	rv = kernel_bind(s, laddr, size);
>  	if (rv < 0)
>  		return rv;
>  
> @@ -1793,8 +1793,8 @@ int siw_create_listen(struct iw_cm_id *id, int backlog)
>  		if (ipv4_is_zeronet(laddr->sin_addr.s_addr))
>  			s->sk->sk_bound_dev_if = sdev->netdev->ifindex;
>  
> -		rv = s->ops->bind(s, (struct sockaddr *)laddr,
> -				  sizeof(struct sockaddr_in));
> +		rv = kernel_bind(s, (struct sockaddr *)laddr,
> +				 sizeof(struct sockaddr_in));
>  	} else {
>  		struct sockaddr_in6 *laddr = &to_sockaddr_in6(id->local_addr);
>  
> @@ -1811,8 +1811,8 @@ int siw_create_listen(struct iw_cm_id *id, int backlog)
>  		if (ipv6_addr_any(&laddr->sin6_addr))
>  			s->sk->sk_bound_dev_if = sdev->netdev->ifindex;
>  
> -		rv = s->ops->bind(s, (struct sockaddr *)laddr,
> -				  sizeof(struct sockaddr_in6));
> +		rv = kernel_bind(s, (struct sockaddr *)laddr,
> +				 sizeof(struct sockaddr_in6));
>  	}
>  	if (rv) {
>  		siw_dbg(id->device, "socket bind error: %d\n", rv);
> diff --git a/drivers/isdn/mISDN/l1oip_core.c b/drivers/isdn/mISDN/l1oip_core.c
> index f010b35a05313..681147e1fc843 100644
> --- a/drivers/isdn/mISDN/l1oip_core.c
> +++ b/drivers/isdn/mISDN/l1oip_core.c
> @@ -675,8 +675,8 @@ l1oip_socket_thread(void *data)
>  	hc->sin_remote.sin_port = htons((unsigned short)hc->remoteport);
>  
>  	/* bind to incoming port */
> -	if (socket->ops->bind(socket, (struct sockaddr *)&hc->sin_local,
> -			      sizeof(hc->sin_local))) {
> +	if (kernel_bind(socket, (struct sockaddr *)&hc->sin_local,
> +			sizeof(hc->sin_local))) {
>  		printk(KERN_ERR "%s: Failed to bind socket to port %d.\n",
>  		       __func__, hc->localport);
>  		ret = -EINVAL;
> diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
> index 1cf796b97eb65..73ab179833fbd 100644
> --- a/fs/dlm/lowcomms.c
> +++ b/fs/dlm/lowcomms.c
> @@ -1805,8 +1805,7 @@ static int dlm_tcp_bind(struct socket *sock)
>  	memcpy(&src_addr, &dlm_local_addr[0], sizeof(src_addr));
>  	make_sockaddr(&src_addr, 0, &addr_len);
>  
> -	result = sock->ops->bind(sock, (struct sockaddr *)&src_addr,
> -				 addr_len);
> +	result = kernel_bind(sock, (struct sockaddr *)&src_addr, addr_len);
>  	if (result < 0) {
>  		/* This *may* not indicate a critical error */
>  		log_print("could not bind for connect: %d", result);
> @@ -1850,8 +1849,8 @@ static int dlm_tcp_listen_bind(struct socket *sock)
>  
>  	/* Bind to our port */
>  	make_sockaddr(&dlm_local_addr[0], dlm_config.ci_tcp_port, &addr_len);
> -	return sock->ops->bind(sock, (struct sockaddr *)&dlm_local_addr[0],
> -			       addr_len);
> +	return kernel_bind(sock, (struct sockaddr *)&dlm_local_addr[0],
> +			   addr_len);
>  }
>  
>  static const struct dlm_proto_ops dlm_tcp_ops = {
> diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
> index ead7c287ff373..3a4a7a521476d 100644
> --- a/fs/ocfs2/cluster/tcp.c
> +++ b/fs/ocfs2/cluster/tcp.c
> @@ -1614,8 +1614,8 @@ static void o2net_start_connect(struct work_struct *work)
>  	myaddr.sin_addr.s_addr = mynode->nd_ipv4_address;
>  	myaddr.sin_port = htons(0); /* any port */
>  
> -	ret = sock->ops->bind(sock, (struct sockaddr *)&myaddr,
> -			      sizeof(myaddr));
> +	ret = kernel_bind(sock, (struct sockaddr *)&myaddr,
> +			  sizeof(myaddr));
>  	if (ret) {
>  		mlog(ML_ERROR, "bind failed with %d at address %pI4\n",
>  		     ret, &mynode->nd_ipv4_address);
> @@ -1998,7 +1998,7 @@ static int o2net_open_listening_sock(__be32 addr, __be16 port)
>  	INIT_WORK(&o2net_listen_work, o2net_accept_many);
>  
>  	sock->sk->sk_reuse = SK_CAN_REUSE;
> -	ret = sock->ops->bind(sock, (struct sockaddr *)&sin, sizeof(sin));
> +	ret = kernel_bind(sock, (struct sockaddr *)&sin, sizeof(sin));
>  	if (ret < 0) {
>  		printk(KERN_ERR "o2net: Error %d while binding socket at "
>  		       "%pI4:%u\n", ret, &addr, ntohs(port)); 
> diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
> index b7764cd57e035..6dcc1cd41b8c5 100644
> --- a/fs/smb/client/connect.c
> +++ b/fs/smb/client/connect.c
> @@ -2891,9 +2891,9 @@ bind_socket(struct TCP_Server_Info *server)
>  	if (server->srcaddr.ss_family != AF_UNSPEC) {
>  		/* Bind to the specified local IP address */
>  		struct socket *socket = server->ssocket;
> -		rc = socket->ops->bind(socket,
> -				       (struct sockaddr *) &server->srcaddr,
> -				       sizeof(server->srcaddr));
> +		rc = kernel_bind(socket,
> +				 (struct sockaddr *)&server->srcaddr,
> +				 sizeof(server->srcaddr));
>  		if (rc < 0) {
>  			struct sockaddr_in *saddr4;
>  			struct sockaddr_in6 *saddr6;
> diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
> index 6e4ed1e11a3b7..4174076c66fa7 100644
> --- a/net/netfilter/ipvs/ip_vs_sync.c
> +++ b/net/netfilter/ipvs/ip_vs_sync.c
> @@ -1439,7 +1439,7 @@ static int bind_mcastif_addr(struct socket *sock, struct net_device *dev)
>  	sin.sin_addr.s_addr  = addr;
>  	sin.sin_port         = 0;
>  
> -	return sock->ops->bind(sock, (struct sockaddr*)&sin, sizeof(sin));
> +	return kernel_bind(sock, (struct sockaddr *)&sin, sizeof(sin));
>  }
>  
>  static void get_mcast_sockaddr(union ipvs_sockaddr *sa, int *salen,
> @@ -1546,7 +1546,7 @@ static int make_receive_sock(struct netns_ipvs *ipvs, int id,
>  
>  	get_mcast_sockaddr(&mcast_addr, &salen, &ipvs->bcfg, id);
>  	sock->sk->sk_bound_dev_if = dev->ifindex;
> -	result = sock->ops->bind(sock, (struct sockaddr *)&mcast_addr, salen);
> +	result = kernel_bind(sock, (struct sockaddr *)&mcast_addr, salen);
>  	if (result < 0) {
>  		pr_err("Error binding to the multicast addr\n");
>  		goto error;
> diff --git a/net/rds/tcp_connect.c b/net/rds/tcp_connect.c
> index d788c6d28986f..a0046e99d6df7 100644
> --- a/net/rds/tcp_connect.c
> +++ b/net/rds/tcp_connect.c
> @@ -145,7 +145,7 @@ int rds_tcp_conn_path_connect(struct rds_conn_path *cp)
>  		addrlen = sizeof(sin);
>  	}
>  
> -	ret = sock->ops->bind(sock, addr, addrlen);
> +	ret = kernel_bind(sock, addr, addrlen);
>  	if (ret) {
>  		rdsdebug("bind failed with %d at address %pI6c\n",
>  			 ret, &conn->c_laddr);
> diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c
> index 014fa24418c12..53b3535a1e4a8 100644
> --- a/net/rds/tcp_listen.c
> +++ b/net/rds/tcp_listen.c
> @@ -306,7 +306,7 @@ struct socket *rds_tcp_listen_init(struct net *net, bool isv6)
>  		addr_len = sizeof(*sin);
>  	}
>  
> -	ret = sock->ops->bind(sock, (struct sockaddr *)&ss, addr_len);
> +	ret = kernel_bind(sock, (struct sockaddr *)&ss, addr_len);
>  	if (ret < 0) {
>  		rdsdebug("could not bind %s listener socket: %d\n",
>  			 isv6 ? "IPv6" : "IPv4", ret);
> diff --git a/net/socket.c b/net/socket.c
> index 2d34a69b84406..9741b408bf5c2 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -3519,6 +3519,13 @@ static long compat_sock_ioctl(struct file *file, unsigned int cmd,
>  
>  int kernel_bind(struct socket *sock, struct sockaddr *addr, int addrlen)
>  {
> +	struct sockaddr_storage address;
> +
> +	if (addrlen < 0 || addrlen > sizeof(address))
> +		return -EINVAL;
> +

Is there any real risk of callers passing these lengths out of bound?

These are in-kernel callers, so they are by necessity trusted code. If
there is a buggy caller, that will be addressed directly, rather than
through these callee precondition checks.

> +	memcpy(&address, addr, addrlen);
> +
>  	return READ_ONCE(sock->ops)->bind(sock, addr, addrlen);

You want to pass &address?

>  }
>  EXPORT_SYMBOL(kernel_bind);
> -- 
> 2.42.0.459.ge4e396fd5e-goog
> 

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