From e8b7db38449ac5b950a3f00519171c4be3e226ff Mon Sep 17 00:00:00 2001 From: Andres Beltran Date: Mon, 9 Nov 2020 11:04:00 +0100 Subject: Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening Currently, VMbus drivers use pointers into guest memory as request IDs for interactions with Hyper-V. To be more robust in the face of errors or malicious behavior from a compromised Hyper-V, avoid exposing guest memory addresses to Hyper-V. Also avoid Hyper-V giving back a bad request ID that is then treated as the address of a guest data structure with no validation. Instead, encapsulate these memory addresses and provide small integers as request IDs. Signed-off-by: Andres Beltran Co-developed-by: Andrea Parri (Microsoft) Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Reviewed-by: Wei Liu Link: https://lore.kernel.org/r/20201109100402.8946-2-parri.andrea@gmail.com Signed-off-by: Wei Liu --- include/linux/hyperv.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'include/linux') diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index 1ce131f29f3b..5b6d5c4e3711 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -764,6 +764,22 @@ enum vmbus_device_type { HV_UNKNOWN, }; +/* + * Provides request ids for VMBus. Encapsulates guest memory + * addresses and stores the next available slot in req_arr + * to generate new ids in constant time. + */ +struct vmbus_requestor { + u64 *req_arr; + unsigned long *req_bitmap; /* is a given slot available? */ + u32 size; + u64 next_request_id; + spinlock_t req_lock; /* provides atomicity */ +}; + +#define VMBUS_NO_RQSTOR U64_MAX +#define VMBUS_RQST_ERROR (U64_MAX - 1) + struct vmbus_device { u16 dev_type; guid_t guid; @@ -988,8 +1004,14 @@ struct vmbus_channel { u32 fuzz_testing_interrupt_delay; u32 fuzz_testing_message_delay; + /* request/transaction ids for VMBus */ + struct vmbus_requestor requestor; + u32 rqstor_size; }; +u64 vmbus_next_request_id(struct vmbus_requestor *rqstor, u64 rqst_addr); +u64 vmbus_request_addr(struct vmbus_requestor *rqstor, u64 trans_id); + static inline bool is_hvsock_channel(const struct vmbus_channel *c) { return !!(c->offermsg.offer.chn_flags & -- cgit v1.2.3 From 4d18fcc95f50950a99bd940d4e61a983f91d267a Mon Sep 17 00:00:00 2001 From: Andres Beltran Date: Mon, 9 Nov 2020 11:04:02 +0100 Subject: hv_netvsc: Use vmbus_requestor to generate transaction IDs for VMBus hardening Currently, pointers to guest memory are passed to Hyper-V as transaction IDs in netvsc. In the face of errors or malicious behavior in Hyper-V, netvsc 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 requests (transaction) IDs. Signed-off-by: Andres Beltran Co-developed-by: Andrea Parri (Microsoft) Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Acked-by: Jakub Kicinski Reviewed-by: Wei Liu Cc: "David S. Miller" Cc: Jakub Kicinski Cc: netdev@vger.kernel.org Link: https://lore.kernel.org/r/20201109100402.8946-4-parri.andrea@gmail.com Signed-off-by: Wei Liu --- drivers/net/hyperv/hyperv_net.h | 13 +++++++++++++ drivers/net/hyperv/netvsc.c | 22 ++++++++++++++++------ drivers/net/hyperv/rndis_filter.c | 1 + include/linux/hyperv.h | 1 + 4 files changed, 31 insertions(+), 6 deletions(-) (limited to 'include/linux') diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h index a0f338cf1424..2a87cfa27ac0 100644 --- a/drivers/net/hyperv/hyperv_net.h +++ b/drivers/net/hyperv/hyperv_net.h @@ -847,6 +847,19 @@ struct nvsp_message { #define NETVSC_XDP_HDRM 256 +#define NETVSC_MIN_OUT_MSG_SIZE (sizeof(struct vmpacket_descriptor) + \ + sizeof(struct nvsp_message)) +#define NETVSC_MIN_IN_MSG_SIZE sizeof(struct vmpacket_descriptor) + +/* Estimated requestor size: + * out_ring_size/min_out_msg_size + in_ring_size/min_in_msg_size + */ +static inline u32 netvsc_rqstor_size(unsigned long ringbytes) +{ + return ringbytes / NETVSC_MIN_OUT_MSG_SIZE + + ringbytes / NETVSC_MIN_IN_MSG_SIZE; +} + #define NETVSC_XFER_HEADER_SIZE(rng_cnt) \ (offsetof(struct vmtransfer_page_packet_header, ranges) + \ (rng_cnt) * sizeof(struct vmtransfer_page_range)) diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index 0c3de94b5178..4dbc0055aed0 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -50,7 +50,7 @@ void netvsc_switch_datapath(struct net_device *ndev, bool vf) vmbus_sendpacket(dev->channel, init_pkt, sizeof(struct nvsp_message), - (unsigned long)init_pkt, + VMBUS_RQST_ID_NO_RESPONSE, VM_PKT_DATA_INBAND, 0); } @@ -163,7 +163,7 @@ static void netvsc_revoke_recv_buf(struct hv_device *device, ret = vmbus_sendpacket(device->channel, revoke_packet, sizeof(struct nvsp_message), - (unsigned long)revoke_packet, + VMBUS_RQST_ID_NO_RESPONSE, VM_PKT_DATA_INBAND, 0); /* If the failure is because the channel is rescinded; * ignore the failure since we cannot send on a rescinded @@ -213,7 +213,7 @@ static void netvsc_revoke_send_buf(struct hv_device *device, ret = vmbus_sendpacket(device->channel, revoke_packet, sizeof(struct nvsp_message), - (unsigned long)revoke_packet, + VMBUS_RQST_ID_NO_RESPONSE, VM_PKT_DATA_INBAND, 0); /* If the failure is because the channel is rescinded; @@ -557,7 +557,7 @@ static int negotiate_nvsp_ver(struct hv_device *device, ret = vmbus_sendpacket(device->channel, init_packet, sizeof(struct nvsp_message), - (unsigned long)init_packet, + VMBUS_RQST_ID_NO_RESPONSE, VM_PKT_DATA_INBAND, 0); return ret; @@ -614,7 +614,7 @@ static int netvsc_connect_vsp(struct hv_device *device, /* Send the init request */ ret = vmbus_sendpacket(device->channel, init_packet, sizeof(struct nvsp_message), - (unsigned long)init_packet, + VMBUS_RQST_ID_NO_RESPONSE, VM_PKT_DATA_INBAND, 0); if (ret != 0) goto cleanup; @@ -695,10 +695,19 @@ static void netvsc_send_tx_complete(struct net_device *ndev, const struct vmpacket_descriptor *desc, int budget) { - struct sk_buff *skb = (struct sk_buff *)(unsigned long)desc->trans_id; struct net_device_context *ndev_ctx = netdev_priv(ndev); + struct sk_buff *skb; u16 q_idx = 0; int queue_sends; + u64 cmd_rqst; + + cmd_rqst = vmbus_request_addr(&channel->requestor, (u64)desc->trans_id); + if (cmd_rqst == VMBUS_RQST_ERROR) { + netdev_err(ndev, "Incorrect transaction id\n"); + return; + } + + skb = (struct sk_buff *)(unsigned long)cmd_rqst; /* Notify the layer above us */ if (likely(skb)) { @@ -1520,6 +1529,7 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device, netvsc_poll, NAPI_POLL_WEIGHT); /* Open the channel */ + device->channel->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes); ret = vmbus_open(device->channel, netvsc_ring_bytes, netvsc_ring_bytes, NULL, 0, netvsc_channel_cb, net_device->chan_table); diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c index b22e47bcfeca..6ae43319ece6 100644 --- a/drivers/net/hyperv/rndis_filter.c +++ b/drivers/net/hyperv/rndis_filter.c @@ -1172,6 +1172,7 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc) /* Set the channel before opening.*/ nvchan->channel = new_sc; + new_sc->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes); ret = vmbus_open(new_sc, netvsc_ring_bytes, netvsc_ring_bytes, NULL, 0, netvsc_channel_cb, nvchan); diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index 5b6d5c4e3711..5ddb479c4d4c 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -779,6 +779,7 @@ struct vmbus_requestor { #define VMBUS_NO_RQSTOR U64_MAX #define VMBUS_RQST_ERROR (U64_MAX - 1) +#define VMBUS_RQST_ID_NO_RESPONSE (U64_MAX - 2) struct vmbus_device { u16 dev_type; -- cgit v1.2.3