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[82.53.3.95]) by smtp.gmail.com with ESMTPSA id z21-20020a170906435500b006e8669fae36sm5644685ejm.189.2022.04.19.05.23.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Apr 2022 05:23:55 -0700 (PDT) From: "Andrea Parri (Microsoft)" To: KY Srinivasan , Haiyang Zhang , Stephen Hemminger , Wei Liu , Dexuan Cui , Michael Kelley , Wei Hu , Lorenzo Pieralisi , Rob Herring , Krzysztof Wilczynski , Bjorn Helgaas Cc: linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, "Andrea Parri (Microsoft)" Subject: [PATCH v2 2/6] PCI: hv: Use vmbus_requestor to generate transaction IDs for VMbus hardening Date: Tue, 19 Apr 2022 14:23:21 +0200 Message-Id: <20220419122325.10078-3-parri.andrea@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220419122325.10078-1-parri.andrea@gmail.com> References: <20220419122325.10078-1-parri.andrea@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, pointers to guest memory are passed to Hyper-V as transaction IDs in hv_pci. In the face of errors or malicious behavior in Hyper-V, hv_pci should not expose or trust the transaction IDs returned by Hyper-V to be valid guest memory addresses. Instead, use small integers generated by vmbus_requestor as request (transaction) IDs. Suggested-by: Michael Kelley Signed-off-by: Andrea Parri (Microsoft) --- drivers/pci/controller/pci-hyperv.c | 39 +++++++++++++++++++++-------- 1 file changed, 29 insertions(+), 10 deletions(-) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index 88b3b56d05228..0252b4bbc8d15 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -91,6 +91,13 @@ static enum pci_protocol_version_t pci_protocol_versions[] = { /* space for 32bit serial number as string */ #define SLOT_NAME_SIZE 11 +/* + * Size of requestor for VMbus; the value is based on the observation + * that having more than one request outstanding is 'rare', and so 64 + * should be generous in ensuring that we don't ever run out. + */ +#define HV_PCI_RQSTOR_SIZE 64 + /* * Message Types */ @@ -1407,7 +1414,7 @@ static void hv_int_desc_free(struct hv_pci_dev *hpdev, int_pkt->wslot.slot = hpdev->desc.win_slot.slot; int_pkt->int_desc = *int_desc; vmbus_sendpacket(hpdev->hbus->hdev->channel, int_pkt, sizeof(*int_pkt), - (unsigned long)&ctxt.pkt, VM_PKT_DATA_INBAND, 0); + 0, VM_PKT_DATA_INBAND, 0); kfree(int_desc); } @@ -2649,7 +2656,7 @@ static void hv_eject_device_work(struct work_struct *work) ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE; ejct_pkt->wslot.slot = hpdev->desc.win_slot.slot; vmbus_sendpacket(hbus->hdev->channel, ejct_pkt, - sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt, + sizeof(*ejct_pkt), 0, VM_PKT_DATA_INBAND, 0); /* For the get_pcichild() in hv_pci_eject_device() */ @@ -2696,8 +2703,9 @@ static void hv_pci_onchannelcallback(void *context) const int packet_size = 0x100; int ret; struct hv_pcibus_device *hbus = context; + struct vmbus_channel *chan = hbus->hdev->channel; u32 bytes_recvd; - u64 req_id; + u64 req_id, req_addr; struct vmpacket_descriptor *desc; unsigned char *buffer; int bufferlen = packet_size; @@ -2715,8 +2723,8 @@ static void hv_pci_onchannelcallback(void *context) return; while (1) { - ret = vmbus_recvpacket_raw(hbus->hdev->channel, buffer, - bufferlen, &bytes_recvd, &req_id); + ret = vmbus_recvpacket_raw(chan, buffer, bufferlen, + &bytes_recvd, &req_id); if (ret == -ENOBUFS) { kfree(buffer); @@ -2743,11 +2751,14 @@ static void hv_pci_onchannelcallback(void *context) switch (desc->type) { case VM_PKT_COMP: - /* - * The host is trusted, and thus it's safe to interpret - * this transaction ID as a pointer. - */ - comp_packet = (struct pci_packet *)req_id; + req_addr = chan->request_addr_callback(chan, req_id); + if (req_addr == VMBUS_RQST_ERROR) { + dev_err(&hbus->hdev->device, + "Invalid transaction ID %llx\n", + req_id); + break; + } + comp_packet = (struct pci_packet *)req_addr; response = (struct pci_response *)buffer; comp_packet->completion_func(comp_packet->compl_ctxt, response, @@ -3428,6 +3439,10 @@ static int hv_pci_probe(struct hv_device *hdev, goto free_dom; } + hdev->channel->next_request_id_callback = vmbus_next_request_id; + hdev->channel->request_addr_callback = vmbus_request_addr; + hdev->channel->rqstor_size = HV_PCI_RQSTOR_SIZE; + ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0, hv_pci_onchannelcallback, hbus); if (ret) @@ -3758,6 +3773,10 @@ static int hv_pci_resume(struct hv_device *hdev) hbus->state = hv_pcibus_init; + hdev->channel->next_request_id_callback = vmbus_next_request_id; + hdev->channel->request_addr_callback = vmbus_request_addr; + hdev->channel->rqstor_size = HV_PCI_RQSTOR_SIZE; + ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0, hv_pci_onchannelcallback, hbus); if (ret) -- 2.25.1