From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f42.google.com (mail-ot1-f42.google.com [209.85.210.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6387A48F857 for ; Tue, 25 Aug 2026 22:32:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787697165; cv=none; b=kw6jT+UiEWizHxjtlQRcwN5iCsYCSDwHqr8UY+T1EmRcSQ19NTaWubQ3vHKJAfrOtRGgPAzQX8wQTPU50hUw0tfj8iP6+e6txtuIrMlHS0l5hdm/OXTBe5OIB4Ij2HAQNnEl6Dz3AF4Rgbm0eLFVpw4w34XEwMfKbT97QrdotT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787697165; c=relaxed/simple; bh=4iqJpbtutOm4R3XsSRye/BVM3lSHQyMhCGLpVeYI+dk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GwXi46KoX676bs1EoVg8r7VaGgqnyjzGRa9iZdaHdw/+Zn9Lh6+yJT6iHDokRgp0simhc6unanxlB1pBBtqT+GrirMKCYmQ/nE4f4tpG3bdAiSr2FIHwR1kzE29HdLWOW1DP8y0grsv5qJZgrGjB+DlP2fjFkJMXHb2CDpSrpOA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=ImXdyWx7; arc=none smtp.client-ip=209.85.210.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ImXdyWx7" Received: by mail-ot1-f42.google.com with SMTP id 46e09a7af769-7e9ecb1e13cso528424a34.3 for ; Tue, 25 Aug 2026 15:32:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1787697161; x=1788301961; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=oAPCDDssQLWXyDbqpT5diYKMULhijQjsUnk18J2kiPw=; b=ImXdyWx7hNcruRjnJH+9eAer6ZxupYdZpK5hXn22o/uTqjKdygExOylpiLmiAMKVis E/f2mzl2MJb6y9AJ0LODYCbwkF6hJz/JFrBNVJ3I8bjydJRgOA17V5RBOFtZrGt4/HJM DmsLCLXtuEfrdmlmdUlgXFBsu2NDkz1thF000P0siZj9WyU+hjjlnMvGjcvOKBIYyPH9 pEIJ/YcZZCoIjUu9i6xQDg1Tvb+Gr9hsVSjsMMkkU6QfyoxqEnjVwQ05qmMe2LW+BROB CE4wNoF6U0gupW14NuAS3rjBzvwZjoxYuqYzLdyC0h7q+OQhghRaELTrIHTGwU8cn0wh Ehbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787697161; x=1788301961; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=oAPCDDssQLWXyDbqpT5diYKMULhijQjsUnk18J2kiPw=; b=GJ77HhkTcp2mCnL9kXr17f8Zy5/l0WXnb5ArAAITo9Ex6CLJnXVH/wB40t0B/OBquc 7xiZiC3zbJocaHS1CMg1vj9sqLrG7o5ZNIzpx7CmtT1nkw+ePlF6VEavCZv0EPs89ygZ VsUaZ3iTAev6lt8VPs7aTsyKV8b3Gjaf7BYLsTBncKDTbAyvKmneQSmymPkRibN0+wf2 TYkDIqky7N7WUflGJbx3cZDeACfVFxghPkNLIXZKpz0+BFqadtYXsZgpxFyuarjscueR SsBiKIErUbzEu2GMLhyJoGBDwDbwE84uayF/LfENNRLe9FpOnyu8ajwe227SDdClLVvo 6d9Q== X-Forwarded-Encrypted: i=1; AHgh+Rp1VtCvpbwYqehQFlwDV8FxQK5WpBaqCyMs3eaPLIHWayhPI9f+rIp2/EwhQhYh+jtwyvY=@vger.kernel.org X-Gm-Message-State: AFuF++mLrZQYR01OMYjvnezxXEGqmQSzjLvaROrN2uCxX2XlFEtQAZuG N/VYk/31j6+1g/HnvpcrFlCObrRjXfrA6m8OEy7hLsLBxmI0smLIaj/1 X-Gm-Gg: AR+sD11SUxprElhWBElP8IyXIOVoLoR/fijYRLCJibDziidq3M9FbE/LHg7cj80bKvn WVi52d1LROoj+T4hZu7dveuBGWxXEHiXOmMFRjut4ftLd8EpDFTlPIc01ML+IxvpRP3CTavpXHO iKhMPJ81Qtb2y34392jC8/idjKSTZuLFg+6j0uIgceTv296ok2Dl4ibHvWvtUqRMEMoyD2eEjoL tIItpo7z3jWuNanvB+OQ7q8Xv466T76TplXtVy2/PnMRI1D0oyQMKwZm7SX05j3uW2eoP+v/2Pt RBQMt7O0P52krKRK2ptcWxONfbsVc/OxjOG7HcflARKC3GRK+LmCI9aoXq8ZGt9eel4Y/33lB+a 8OUPjXuSOpPDLQBw2+CU4e/cW4PuIwAwIty+jwlZG81F2RNyaEGdyP0fpButExBwkGk/28Q3dq5 UeHm8PtxJ+PN3BvOPMaMadYihVYFxsdczRrm3njQvLAggmcw+0cA7znt9ARB/RLKV94yLuRPO/0 Kx+K948wQ== X-Received: by 2002:a05:6820:2016:b0:6ac:9729:6710 with SMTP id 006d021491bc7-6b1a049e03bmr2588322eaf.18.1787697160680; Tue, 25 Aug 2026 15:32:40 -0700 (PDT) Received: from devvm29614.prn0.facebook.com ([2a03:2880:ff:4d::]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-6b1a24bdb31sm194474eaf.2.2026.08.25.15.32.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Aug 2026 15:32:40 -0700 (PDT) Date: Tue, 25 Aug 2026 15:32:36 -0700 From: Bobby Eshleman To: Daehyeon Ko <4ncienth@gmail.com> Cc: netdev@vger.kernel.org, sgarzare@redhat.com, stefanha@redhat.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, mst@redhat.com, jasowangio@gmail.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, bryan-bt.tan@broadcom.com, vishnu.dasa@broadcom.com, bcm-kernel-feedback-list@broadcom.com, virtualization@lists.linux.dev, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net v3 1/2] vsock/virtio: validate packet source for connected sockets Message-ID: References: <20260823175858.351431-1-4ncienth@gmail.com> <20260823175858.351431-2-4ncienth@gmail.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260823175858.351431-2-4ncienth@gmail.com> On Mon, Aug 24, 2026 at 02:58:57AM +0900, Daehyeon Ko wrote: > virtio_transport_recv_pkt() looks up sockets first by the full source and > destination tuple, then by destination only in the bound table. The > fallback is needed for listening and connecting sockets, but sockets remain > in the bound table after connect(), so it can also return a non-listening > socket. > > The fallback does not validate the source address. In TCP_SYN_SENT, a > RESPONSE from an unrelated source can transition the victim socket to > TCP_ESTABLISHED while its stored remote address remains unchanged. > Subsequent RW packets from that source are delivered through the same > destination-only fallback. > > This was reproduced with capability-empty processes under different UIDs. > The attacker discovered the target tuple through unprivileged AF_VSOCK > sock_diag and caused the victim socket to read 16 attacker-chosen bytes; > the intended peer-side socket read 0 of those 16 bytes. > > Add vsock_check_source() to validate the transport, source port and source > CID against the peer stored in a non-listening socket. The local transport > is the CID exception because its packets are generated internally with > VMADDR_CID_LOCAL as their source, including connections using CID aliases. > > Use the helper after lock_sock() in the virtio receive path. > > Fixes: 06a8fc78367d ("VSOCK: Introduce virtio_vsock_common.ko") > Closes: https://lore.kernel.org/netdev/20260813121236.2328599-1-4ncienth@gmail.com/ > Cc: stable@vger.kernel.org > Suggested-by: Stefano Garzarella > Assisted-by: Codex:gpt-5.6-sol > Signed-off-by: Daehyeon Ko <4ncienth@gmail.com> > --- > include/net/af_vsock.h | 3 +++ > net/vmw_vsock/af_vsock.c | 32 +++++++++++++++++++++++++ > net/vmw_vsock/virtio_transport_common.c | 3 ++- > 3 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h > index 3357ee62d..5549298c1 100644 > --- a/include/net/af_vsock.h > +++ b/include/net/af_vsock.h > @@ -229,6 +229,9 @@ struct sock *vsock_find_bound_socket_net(struct sockaddr_vm *addr, > struct sock *vsock_find_connected_socket_net(struct sockaddr_vm *src, > struct sockaddr_vm *dst, > struct net *net); > +bool vsock_check_source(const struct vsock_sock *vsk, > + const struct vsock_transport *transport, > + const struct sockaddr_vm *src); > void vsock_remove_sock(struct vsock_sock *vsk); > void vsock_for_each_connected_socket(struct vsock_transport *transport, > void (*fn)(struct sock *sk)); > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c > index a33b2a2d3..f840498b5 100644 > --- a/net/vmw_vsock/af_vsock.c > +++ b/net/vmw_vsock/af_vsock.c > @@ -438,6 +438,38 @@ struct sock *vsock_find_connected_socket(struct sockaddr_vm *src, > } > EXPORT_SYMBOL_GPL(vsock_find_connected_socket); > > +/** > + * vsock_check_source - validate a packet source against a socket peer > + * @vsk: socket receiving the packet > + * @transport: transport receiving the packet > + * @src: source address from the packet > + * > + * Return: true if the packet arrived on the socket's assigned transport and > + * its source matches the stored peer. Loopback packets are generated > + * internally and always use the local CID as their source, including > + * connections using a valid CID alias. > + * > + * The caller must hold the socket lock and must not call this for listening > + * sockets, which accept packets from any source and have no assigned > + * transport. > + */ > +bool vsock_check_source(const struct vsock_sock *vsk, > + const struct vsock_transport *transport, > + const struct sockaddr_vm *src) > +{ > + if (vsk->transport != transport) > + return false; > + > + if (src->svm_port != vsk->remote_addr.svm_port) > + return false; > + > + if (src->svm_cid == vsk->remote_addr.svm_cid) > + return true; > + > + return transport->get_local_cid() == VMADDR_CID_LOCAL; > +} > +EXPORT_SYMBOL_GPL(vsock_check_source); > + > void vsock_remove_sock(struct vsock_sock *vsk) > { > /* Transport reassignment must not remove the binding. */ > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > index e4ebaa70f..6301c108a 100644 > --- a/net/vmw_vsock/virtio_transport_common.c > +++ b/net/vmw_vsock/virtio_transport_common.c > @@ -1823,7 +1823,8 @@ void virtio_transport_recv_pkt(struct virtio_transport *t, > * lock_sock (note: listener sockets are not assigned to any transport) > */ > if (sock_flag(sk, SOCK_DONE) || > - (sk->sk_state != TCP_LISTEN && vsk->transport != &t->transport)) { > + (sk->sk_state != TCP_LISTEN && > + !vsock_check_source(vsk, &t->transport, &src))) { > (void)virtio_transport_reset_no_sock(t, skb, net); > release_sock(sk); > sock_put(sk); > -- > 2.54.0 > Reviewed-by: Bobby Eshleman