[PATCH net v5 1/3] net: replace calls to sock->ops->connect() with kernel_connect()

[PATCH net v5 1/3] net: replace calls to sock->ops->connect() with kernel_connect()

[Jordan Rife]

commit 0bdf399342c5 ("net: Avoid address overwrite in kernel_connect")
ensured that kernel_connect() will not overwrite the address parameter
in cases where BPF connect hooks perform an address rewrite. This change
replaces direct calls to sock->ops->connect() in net with kernel_connect()
to make these call safe.

Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
Fixes: d74bad4e74ee ("bpf: Hooks for sys_connect")
Cc: stable@vger.kernel.org
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jordan Rife <jrife@google.com>
---
v4->v5: Remove non-net changes.
v3->v4: Remove precondition check for addrlen.
v2->v3: Add "Fixes" tag. Check for positivity in addrlen sanity check.
v1->v2: Split up original patch into patch series. Insulate calls with
        kernel_connect() instead of pushing address copy deeper into
        sock->ops->connect().

 net/netfilter/ipvs/ip_vs_sync.c | 4 ++--
 net/rds/tcp_connect.c           | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
index da5af28ff57b5..6e4ed1e11a3b7 100644
--- a/net/netfilter/ipvs/ip_vs_sync.c
+++ b/net/netfilter/ipvs/ip_vs_sync.c
@@ -1505,8 +1505,8 @@ static int make_send_sock(struct netns_ipvs *ipvs, int id,
 	}
 
 	get_mcast_sockaddr(&mcast_addr, &salen, &ipvs->mcfg, id);
-	result = sock->ops->connect(sock, (struct sockaddr *) &mcast_addr,
-				    salen, 0);
+	result = kernel_connect(sock, (struct sockaddr *)&mcast_addr,
+				salen, 0);
 	if (result < 0) {
 		pr_err("Error connecting to the multicast addr\n");
 		goto error;
diff --git a/net/rds/tcp_connect.c b/net/rds/tcp_connect.c
index f0c477c5d1db4..d788c6d28986f 100644
--- a/net/rds/tcp_connect.c
+++ b/net/rds/tcp_connect.c
@@ -173,7 +173,7 @@ int rds_tcp_conn_path_connect(struct rds_conn_path *cp)
 	 * own the socket
 	 */
 	rds_tcp_set_callbacks(sock, cp);
-	ret = sock->ops->connect(sock, addr, addrlen, O_NONBLOCK);
+	ret = kernel_connect(sock, addr, addrlen, O_NONBLOCK);
 
 	rdsdebug("connect to address %pI6c returned %d\n", &conn->c_faddr, ret);
 	if (ret == -EINPROGRESS)
-- 
2.42.0.515.g380fc7ccd1-goog

[PATCH net v5 2/3] net: prevent rewrite of msg_name in sock_sendmsg()

[Jordan Rife]

Callers of sock_sendmsg(), and similarly kernel_sendmsg(), in kernel
space may observe their value of msg_name change in cases where BPF
sendmsg hooks rewrite the send address. This has been confirmed to break
NFS mounts running in UDP mode and has the potential to break other
systems.

This patch:

1) Creates a new function called __sock_sendmsg() with same logic as the
   old sock_sendmsg() function.
2) Replaces calls to sock_sendmsg() made by __sys_sendto() and
   __sys_sendmsg() with __sock_sendmsg() to avoid an unnecessary copy,
   as these system calls are already protected.
3) Modifies sock_sendmsg() so that it makes a copy of msg_name if
   present before passing it down the stack to insulate callers from
   changes to the send address.

Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
Fixes: 1cedee13d25a ("bpf: Hooks for sys_sendmsg")
Cc: stable@vger.kernel.org
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jordan Rife <jrife@google.com>
---
v4->v5: Remove non-net changes.
v3->v4: Maintain reverse xmas tree order for variable declarations.
	Remove precondition check for msg_namelen.
v2->v3: Add "Fixes" tag.
v1->v2: Split up original patch into patch series. Perform address copy
        in sock_sendmsg() instead of sock->ops->sendmsg().

 net/socket.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index c8b08b32f097e..a39ec136f5cff 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -737,6 +737,14 @@ static inline int sock_sendmsg_nosec(struct socket *sock, struct msghdr *msg)
 	return ret;
 }
 
+static int __sock_sendmsg(struct socket *sock, struct msghdr *msg)
+{
+	int err = security_socket_sendmsg(sock, msg,
+					  msg_data_left(msg));
+
+	return err ?: sock_sendmsg_nosec(sock, msg);
+}
+
 /**
  *	sock_sendmsg - send a message through @sock
  *	@sock: socket
@@ -747,10 +755,19 @@ static inline int sock_sendmsg_nosec(struct socket *sock, struct msghdr *msg)
  */
 int sock_sendmsg(struct socket *sock, struct msghdr *msg)
 {
-	int err = security_socket_sendmsg(sock, msg,
-					  msg_data_left(msg));
+	struct sockaddr_storage *save_addr = (struct sockaddr_storage *)msg->msg_name;
+	struct sockaddr_storage address;
+	int ret;
 
-	return err ?: sock_sendmsg_nosec(sock, msg);
+	if (msg->msg_name) {
+		memcpy(&address, msg->msg_name, msg->msg_namelen);
+		msg->msg_name = &address;
+	}
+
+	ret = __sock_sendmsg(sock, msg);
+	msg->msg_name = save_addr;
+
+	return ret;
 }
 EXPORT_SYMBOL(sock_sendmsg);
 
@@ -1138,7 +1155,7 @@ static ssize_t sock_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (sock->type == SOCK_SEQPACKET)
 		msg.msg_flags |= MSG_EOR;
 
-	res = sock_sendmsg(sock, &msg);
+	res = __sock_sendmsg(sock, &msg);
 	*from = msg.msg_iter;
 	return res;
 }
@@ -2174,7 +2191,7 @@ int __sys_sendto(int fd, void __user *buff, size_t len, unsigned int flags,
 	if (sock->file->f_flags & O_NONBLOCK)
 		flags |= MSG_DONTWAIT;
 	msg.msg_flags = flags;
-	err = sock_sendmsg(sock, &msg);
+	err = __sock_sendmsg(sock, &msg);
 
 out_put:
 	fput_light(sock->file, fput_needed);
@@ -2538,7 +2555,7 @@ static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys,
 		err = sock_sendmsg_nosec(sock, msg_sys);
 		goto out_freectl;
 	}
-	err = sock_sendmsg(sock, msg_sys);
+	err = __sock_sendmsg(sock, msg_sys);
 	/*
 	 * If this is sendmmsg() and sending to current destination address was
 	 * successful, remember it.
-- 
2.42.0.515.g380fc7ccd1-goog

[PATCH net v5 3/3] net: prevent address rewrite in kernel_bind()

[Jordan Rife]

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() in net with kernel_bind()

Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
Fixes: 4fbac77d2d09 ("bpf: Hooks for sys_bind")
Cc: stable@vger.kernel.org
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jordan Rife <jrife@google.com>
---
v4->v5: Remove non-net changes.
v3->v4: Remove precondition check for addrlen. Pass address copy to
        bind() instead of original address.
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().

 net/netfilter/ipvs/ip_vs_sync.c | 4 ++--
 net/rds/tcp_connect.c           | 2 +-
 net/rds/tcp_listen.c            | 2 +-
 net/socket.c                    | 7 ++++++-
 4 files changed, 10 insertions(+), 5 deletions(-)

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 a39ec136f5cff..c4a6f55329552 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -3516,7 +3516,12 @@ static long compat_sock_ioctl(struct file *file, unsigned int cmd,
 
 int kernel_bind(struct socket *sock, struct sockaddr *addr, int addrlen)
 {
-	return READ_ONCE(sock->ops)->bind(sock, addr, addrlen);
+	struct sockaddr_storage address;
+
+	memcpy(&address, addr, addrlen);
+
+	return READ_ONCE(sock->ops)->bind(sock, (struct sockaddr *)&address,
+					  addrlen);
 }
 EXPORT_SYMBOL(kernel_bind);
 
-- 
2.42.0.515.g380fc7ccd1-goog

Re: [PATCH net v5 1/3] net: replace calls to sock->ops->connect() with kernel_connect()

[Simon Horman]

On Thu, Sep 21, 2023 at 06:46:40PM -0500, Jordan Rife wrote:
> commit 0bdf399342c5 ("net: Avoid address overwrite in kernel_connect")
> ensured that kernel_connect() will not overwrite the address parameter
> in cases where BPF connect hooks perform an address rewrite. This change
> replaces direct calls to sock->ops->connect() in net with kernel_connect()
> to make these call safe.
> 
> Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
> Fixes: d74bad4e74ee ("bpf: Hooks for sys_connect")
> Cc: stable@vger.kernel.org
> Reviewed-by: Willem de Bruijn <willemb@google.com>
> Signed-off-by: Jordan Rife <jrife@google.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net v5 2/3] net: prevent rewrite of msg_name in sock_sendmsg()

[Simon Horman]

On Thu, Sep 21, 2023 at 06:46:41PM -0500, Jordan Rife wrote:
> Callers of sock_sendmsg(), and similarly kernel_sendmsg(), in kernel
> space may observe their value of msg_name change in cases where BPF
> sendmsg hooks rewrite the send address. This has been confirmed to break
> NFS mounts running in UDP mode and has the potential to break other
> systems.
> 
> This patch:
> 
> 1) Creates a new function called __sock_sendmsg() with same logic as the
>    old sock_sendmsg() function.
> 2) Replaces calls to sock_sendmsg() made by __sys_sendto() and
>    __sys_sendmsg() with __sock_sendmsg() to avoid an unnecessary copy,
>    as these system calls are already protected.
> 3) Modifies sock_sendmsg() so that it makes a copy of msg_name if
>    present before passing it down the stack to insulate callers from
>    changes to the send address.
> 
> Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
> Fixes: 1cedee13d25a ("bpf: Hooks for sys_sendmsg")
> Cc: stable@vger.kernel.org
> Reviewed-by: Willem de Bruijn <willemb@google.com>
> Signed-off-by: Jordan Rife <jrife@google.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net v5 3/3] net: prevent address rewrite in kernel_bind()

[Simon Horman]

On Thu, Sep 21, 2023 at 06:46:42PM -0500, 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() in net with kernel_bind()
> 
> Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
> Fixes: 4fbac77d2d09 ("bpf: Hooks for sys_bind")
> Cc: stable@vger.kernel.org
> Reviewed-by: Willem de Bruijn <willemb@google.com>
> Signed-off-by: Jordan Rife <jrife@google.com>

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net v5 1/3] net: replace calls to sock->ops->connect() with kernel_connect()

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Thu, 21 Sep 2023 18:46:40 -0500 you wrote:
> commit 0bdf399342c5 ("net: Avoid address overwrite in kernel_connect")
> ensured that kernel_connect() will not overwrite the address parameter
> in cases where BPF connect hooks perform an address rewrite. This change
> replaces direct calls to sock->ops->connect() in net with kernel_connect()
> to make these call safe.
> 
> Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
> Fixes: d74bad4e74ee ("bpf: Hooks for sys_connect")
> Cc: stable@vger.kernel.org
> Reviewed-by: Willem de Bruijn <willemb@google.com>
> Signed-off-by: Jordan Rife <jrife@google.com>
> 
> [...]

Here is the summary with links:
  - [net,v5,1/3] net: replace calls to sock->ops->connect() with kernel_connect()
    https://git.kernel.org/netdev/net/c/26297b4ce1ce
  - [net,v5,2/3] net: prevent rewrite of msg_name in sock_sendmsg()
    https://git.kernel.org/netdev/net/c/86a7e0b69bd5
  - [net,v5,3/3] net: prevent address rewrite in kernel_bind()
    https://git.kernel.org/netdev/net/c/c889a99a21bf

You are awesome, thank you!
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