2
0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-24 05:04:00 +08:00

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 <lkmlabelt@gmail.com>
Co-developed-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20201109100402.8946-2-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Andres Beltran 2020-11-09 11:04:00 +01:00 committed by Wei Liu
parent 09162bc32c
commit e8b7db3844
4 changed files with 219 additions and 9 deletions

View File

@ -503,6 +503,70 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
}
EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
/**
* request_arr_init - Allocates memory for the requestor array. Each slot
* keeps track of the next available slot in the array. Initially, each
* slot points to the next one (as in a Linked List). The last slot
* does not point to anything, so its value is U64_MAX by default.
* @size The size of the array
*/
static u64 *request_arr_init(u32 size)
{
int i;
u64 *req_arr;
req_arr = kcalloc(size, sizeof(u64), GFP_KERNEL);
if (!req_arr)
return NULL;
for (i = 0; i < size - 1; i++)
req_arr[i] = i + 1;
/* Last slot (no more available slots) */
req_arr[i] = U64_MAX;
return req_arr;
}
/*
* vmbus_alloc_requestor - Initializes @rqstor's fields.
* Index 0 is the first free slot
* @size: Size of the requestor array
*/
static int vmbus_alloc_requestor(struct vmbus_requestor *rqstor, u32 size)
{
u64 *rqst_arr;
unsigned long *bitmap;
rqst_arr = request_arr_init(size);
if (!rqst_arr)
return -ENOMEM;
bitmap = bitmap_zalloc(size, GFP_KERNEL);
if (!bitmap) {
kfree(rqst_arr);
return -ENOMEM;
}
rqstor->req_arr = rqst_arr;
rqstor->req_bitmap = bitmap;
rqstor->size = size;
rqstor->next_request_id = 0;
spin_lock_init(&rqstor->req_lock);
return 0;
}
/*
* vmbus_free_requestor - Frees memory allocated for @rqstor
* @rqstor: Pointer to the requestor struct
*/
static void vmbus_free_requestor(struct vmbus_requestor *rqstor)
{
kfree(rqstor->req_arr);
bitmap_free(rqstor->req_bitmap);
}
static int __vmbus_open(struct vmbus_channel *newchannel,
void *userdata, u32 userdatalen,
void (*onchannelcallback)(void *context), void *context)
@ -523,6 +587,12 @@ static int __vmbus_open(struct vmbus_channel *newchannel,
if (newchannel->state != CHANNEL_OPEN_STATE)
return -EINVAL;
/* Create and init requestor */
if (newchannel->rqstor_size) {
if (vmbus_alloc_requestor(&newchannel->requestor, newchannel->rqstor_size))
return -ENOMEM;
}
newchannel->state = CHANNEL_OPENING_STATE;
newchannel->onchannel_callback = onchannelcallback;
newchannel->channel_callback_context = context;
@ -626,6 +696,7 @@ error_free_gpadl:
error_clean_ring:
hv_ringbuffer_cleanup(&newchannel->outbound);
hv_ringbuffer_cleanup(&newchannel->inbound);
vmbus_free_requestor(&newchannel->requestor);
newchannel->state = CHANNEL_OPEN_STATE;
return err;
}
@ -808,6 +879,9 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
channel->ringbuffer_gpadlhandle = 0;
}
if (!ret)
vmbus_free_requestor(&channel->requestor);
return ret;
}
@ -888,7 +962,7 @@ int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
/* in 8-bytes granularity */
desc.offset8 = sizeof(struct vmpacket_descriptor) >> 3;
desc.len8 = (u16)(packetlen_aligned >> 3);
desc.trans_id = requestid;
desc.trans_id = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
bufferlist[0].iov_base = &desc;
bufferlist[0].iov_len = sizeof(struct vmpacket_descriptor);
@ -897,7 +971,7 @@ int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
bufferlist[2].iov_base = &aligned_data;
bufferlist[2].iov_len = (packetlen_aligned - packetlen);
return hv_ringbuffer_write(channel, bufferlist, num_vecs);
return hv_ringbuffer_write(channel, bufferlist, num_vecs, requestid);
}
EXPORT_SYMBOL(vmbus_sendpacket);
@ -939,7 +1013,7 @@ int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
desc.flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
desc.dataoffset8 = descsize >> 3; /* in 8-bytes granularity */
desc.length8 = (u16)(packetlen_aligned >> 3);
desc.transactionid = requestid;
desc.transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
desc.reserved = 0;
desc.rangecount = pagecount;
@ -956,7 +1030,7 @@ int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
bufferlist[2].iov_base = &aligned_data;
bufferlist[2].iov_len = (packetlen_aligned - packetlen);
return hv_ringbuffer_write(channel, bufferlist, 3);
return hv_ringbuffer_write(channel, bufferlist, 3, requestid);
}
EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
@ -983,7 +1057,7 @@ int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
desc->flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
desc->dataoffset8 = desc_size >> 3; /* in 8-bytes granularity */
desc->length8 = (u16)(packetlen_aligned >> 3);
desc->transactionid = requestid;
desc->transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
desc->reserved = 0;
desc->rangecount = 1;
@ -994,7 +1068,7 @@ int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
bufferlist[2].iov_base = &aligned_data;
bufferlist[2].iov_len = (packetlen_aligned - packetlen);
return hv_ringbuffer_write(channel, bufferlist, 3);
return hv_ringbuffer_write(channel, bufferlist, 3, requestid);
}
EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
@ -1042,3 +1116,91 @@ int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer,
buffer_actual_len, requestid, true);
}
EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);
/*
* vmbus_next_request_id - Returns a new request id. It is also
* the index at which the guest memory address is stored.
* Uses a spin lock to avoid race conditions.
* @rqstor: Pointer to the requestor struct
* @rqst_add: Guest memory address to be stored in the array
*/
u64 vmbus_next_request_id(struct vmbus_requestor *rqstor, u64 rqst_addr)
{
unsigned long flags;
u64 current_id;
const struct vmbus_channel *channel =
container_of(rqstor, const struct vmbus_channel, requestor);
/* Check rqstor has been initialized */
if (!channel->rqstor_size)
return VMBUS_NO_RQSTOR;
spin_lock_irqsave(&rqstor->req_lock, flags);
current_id = rqstor->next_request_id;
/* Requestor array is full */
if (current_id >= rqstor->size) {
spin_unlock_irqrestore(&rqstor->req_lock, flags);
return VMBUS_RQST_ERROR;
}
rqstor->next_request_id = rqstor->req_arr[current_id];
rqstor->req_arr[current_id] = rqst_addr;
/* The already held spin lock provides atomicity */
bitmap_set(rqstor->req_bitmap, current_id, 1);
spin_unlock_irqrestore(&rqstor->req_lock, flags);
/*
* Cannot return an ID of 0, which is reserved for an unsolicited
* message from Hyper-V.
*/
return current_id + 1;
}
EXPORT_SYMBOL_GPL(vmbus_next_request_id);
/*
* vmbus_request_addr - Returns the memory address stored at @trans_id
* in @rqstor. Uses a spin lock to avoid race conditions.
* @rqstor: Pointer to the requestor struct
* @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
* next request id.
*/
u64 vmbus_request_addr(struct vmbus_requestor *rqstor, u64 trans_id)
{
unsigned long flags;
u64 req_addr;
const struct vmbus_channel *channel =
container_of(rqstor, const struct vmbus_channel, requestor);
/* Check rqstor has been initialized */
if (!channel->rqstor_size)
return VMBUS_NO_RQSTOR;
/* Hyper-V can send an unsolicited message with ID of 0 */
if (!trans_id)
return trans_id;
spin_lock_irqsave(&rqstor->req_lock, flags);
/* Data corresponding to trans_id is stored at trans_id - 1 */
trans_id--;
/* Invalid trans_id */
if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {
spin_unlock_irqrestore(&rqstor->req_lock, flags);
return VMBUS_RQST_ERROR;
}
req_addr = rqstor->req_arr[trans_id];
rqstor->req_arr[trans_id] = rqstor->next_request_id;
rqstor->next_request_id = trans_id;
/* The already held spin lock provides atomicity */
bitmap_clear(rqstor->req_bitmap, trans_id, 1);
spin_unlock_irqrestore(&rqstor->req_lock, flags);
return req_addr;
}
EXPORT_SYMBOL_GPL(vmbus_request_addr);

View File

@ -179,7 +179,8 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
int hv_ringbuffer_write(struct vmbus_channel *channel,
const struct kvec *kv_list, u32 kv_count);
const struct kvec *kv_list, u32 kv_count,
u64 requestid);
int hv_ringbuffer_read(struct vmbus_channel *channel,
void *buffer, u32 buflen, u32 *buffer_actual_len,

View File

@ -248,7 +248,8 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
/* Write to the ring buffer. */
int hv_ringbuffer_write(struct vmbus_channel *channel,
const struct kvec *kv_list, u32 kv_count)
const struct kvec *kv_list, u32 kv_count,
u64 requestid)
{
int i;
u32 bytes_avail_towrite;
@ -258,6 +259,8 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
u64 prev_indices;
unsigned long flags;
struct hv_ring_buffer_info *outring_info = &channel->outbound;
struct vmpacket_descriptor *desc = kv_list[0].iov_base;
u64 rqst_id = VMBUS_NO_RQSTOR;
if (channel->rescind)
return -ENODEV;
@ -300,6 +303,23 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
kv_list[i].iov_len);
}
/*
* Allocate the request ID after the data has been copied into the
* ring buffer. Once this request ID is allocated, the completion
* path could find the data and free it.
*/
if (desc->flags == VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED) {
rqst_id = vmbus_next_request_id(&channel->requestor, requestid);
if (rqst_id == VMBUS_RQST_ERROR) {
spin_unlock_irqrestore(&outring_info->ring_lock, flags);
pr_err("No request id available\n");
return -EAGAIN;
}
}
desc = hv_get_ring_buffer(outring_info) + old_write;
desc->trans_id = (rqst_id == VMBUS_NO_RQSTOR) ? requestid : rqst_id;
/* Set previous packet start */
prev_indices = hv_get_ring_bufferindices(outring_info);
@ -319,8 +339,13 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
hv_signal_on_write(old_write, channel);
if (channel->rescind)
if (channel->rescind) {
if (rqst_id != VMBUS_NO_RQSTOR) {
/* Reclaim request ID to avoid leak of IDs */
vmbus_request_addr(&channel->requestor, rqst_id);
}
return -ENODEV;
}
return 0;
}

View File

@ -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 &