[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [RFC PATCH 15/19] tools/vhost-user-rpmb: implement VIRTIO_RPMB_REQ_
From: |
Joakim Bech |
Subject: |
Re: [RFC PATCH 15/19] tools/vhost-user-rpmb: implement VIRTIO_RPMB_REQ_DATA_WRITE |
Date: |
Mon, 28 Sep 2020 15:52:01 +0200 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Fri, Sep 25, 2020 at 01:51:43PM +0100, Alex Bennée wrote:
> With this command we are finally updating data to the backing store
> and cycling the write_count and each successful write. We also include
> the write count in all response frames as the spec is a little unclear
> but the example test code expected it.
>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
> tools/vhost-user-rpmb/main.c | 111 +++++++++++++++++++++++++++++++++--
> 1 file changed, 105 insertions(+), 6 deletions(-)
>
> diff --git a/tools/vhost-user-rpmb/main.c b/tools/vhost-user-rpmb/main.c
> index 88747c50fa44..a17c3b4bcc4e 100644
> --- a/tools/vhost-user-rpmb/main.c
> +++ b/tools/vhost-user-rpmb/main.c
> @@ -62,6 +62,7 @@ enum {
> #define KiB (1UL << 10)
> #define MAX_RPMB_SIZE (KiB * 128 * 256)
> #define RPMB_KEY_MAC_SIZE 32
> +#define RPMB_BLOCK_SIZE 256
>
> /* RPMB Request Types */
> #define VIRTIO_RPMB_REQ_PROGRAM_KEY 0x0001
> @@ -100,7 +101,7 @@ struct virtio_rpmb_config {
> struct virtio_rpmb_frame {
> uint8_t stuff[196];
> uint8_t key_mac[RPMB_KEY_MAC_SIZE];
> - uint8_t data[256];
> + uint8_t data[RPMB_BLOCK_SIZE];
> uint8_t nonce[16];
> /* remaining fields are big-endian */
> uint32_t write_counter;
> @@ -124,6 +125,7 @@ typedef struct VuRpmb {
> uint8_t last_nonce[16];
> uint16_t last_result;
> uint16_t last_reqresp;
> + uint16_t last_address;
> uint32_t write_count;
> } VuRpmb;
>
> @@ -239,17 +241,30 @@ vrpmb_set_config(VuDev *dev, const uint8_t *data,
> * which itself uses a 3 clause BSD chunk of code.
> */
>
> +static const int rpmb_frame_dlen = (sizeof(struct virtio_rpmb_frame) -
> + offsetof(struct virtio_rpmb_frame,
> data));
> +
> static void vrpmb_update_mac_in_frame(VuRpmb *r, struct virtio_rpmb_frame
> *frm)
> {
> hmac_sha256_ctx ctx;
> - static const int dlen = (sizeof(struct virtio_rpmb_frame) -
> - offsetof(struct virtio_rpmb_frame, data));
>
> hmac_sha256_init(&ctx, r->key, RPMB_KEY_MAC_SIZE);
> - hmac_sha256_update(&ctx, frm->data, dlen);
> + hmac_sha256_update(&ctx, frm->data, rpmb_frame_dlen);
> hmac_sha256_final(&ctx, &frm->key_mac[0], 32);
> }
>
> +static bool vrpmb_verify_mac_in_frame(VuRpmb *r, struct virtio_rpmb_frame
> *frm)
> +{
> + hmac_sha256_ctx ctx;
> + uint8_t calculated_mac[RPMB_KEY_MAC_SIZE];
> +
> + hmac_sha256_init(&ctx, r->key, RPMB_KEY_MAC_SIZE);
> + hmac_sha256_update(&ctx, frm->data, rpmb_frame_dlen);
> + hmac_sha256_final(&ctx, calculated_mac, RPMB_KEY_MAC_SIZE);
> +
> + return memcmp(calculated_mac, frm->key_mac, RPMB_KEY_MAC_SIZE) == 0;
>
I'd prefer using a constant time comparison function for this one
instead of memcmp (regardless if it's used for simulation or not) to
prevent eventual timing attacks.
> +}
> +
> /*
> * Handlers for individual control messages
> */
> @@ -324,6 +339,82 @@ vrpmb_handle_get_write_counter(VuDev *dev, struct
> virtio_rpmb_frame *frame)
> return resp;
> }
>
> +/*
> + * vrpmb_handle_write:
> + *
> + * We will report the success/fail on receipt of
> + * VIRTIO_RPMB_REQ_RESULT_READ. Returns the number of extra frames
> + * processed in the request.
> + */
> +static int vrpmb_handle_write(VuDev *dev, struct virtio_rpmb_frame *frame)
> +{
> + VuRpmb *r = container_of(dev, VuRpmb, dev.parent);
> + int extra_frames = 0;
> + uint16_t block_count = be16toh(frame->block_count);
> + uint32_t write_counter = be32toh(frame->write_counter);
> + size_t offset;
> +
> + r->last_reqresp = VIRTIO_RPMB_RESP_DATA_WRITE;
> + r->last_address = be16toh(frame->address);
> + offset = r->last_address * RPMB_BLOCK_SIZE;
> +
> + /*
> + * Run the checks from:
> + * 5.12.6.1.3 Device Requirements: Device Operation: Data Write
> + */
> + if (!r->key) {
> + g_warning("no key programmed");
> + r->last_result = VIRTIO_RPMB_RES_NO_AUTH_KEY;
> + } else if (block_count == 0 ||
> + block_count > r->virtio_config.max_wr_cnt) {
> + r->last_result = VIRTIO_RPMB_RES_GENERAL_FAILURE;
> + } else if (false /* what does an expired write counter mean? */) {
>
IIRC, the counter has room for a 32-bit value and the counter will never
wrap around. So once the counter have reached max for uint32_t, then
there is an additional bit set (permanently) in the operation result.
I.e., writes are no longer possible once that has happened. That is
probably what you're referring to here I suppose.
> + r->last_result = VIRTIO_RPMB_RES_WRITE_COUNTER_EXPIRED;
> + } else if (offset > (r->virtio_config.capacity * (128 * KiB))) {
> + r->last_result = VIRTIO_RPMB_RES_ADDR_FAILURE;
> + } else if (!vrpmb_verify_mac_in_frame(r, frame)) {
> + r->last_result = VIRTIO_RPMB_RES_AUTH_FAILURE;
> + } else if (write_counter != r->write_count) {
> + r->last_result = VIRTIO_RPMB_RES_COUNT_FAILURE;
> + } else {
> + int i;
> + /* At this point we have a valid authenticated write request
> + * so the counter can incremented and we can attempt to
> + * update the backing device.
> + */
> + r->write_count++;
> + for (i = 0; i < block_count; i++) {
> + void *blk = r->flash_map + offset;
> + g_debug("%s: writing block %d", __func__, i);
> + if (mprotect(blk, RPMB_BLOCK_SIZE, PROT_WRITE) != 0) {
> + r->last_result = VIRTIO_RPMB_RES_WRITE_FAILURE;
> + break;
> + }
> + memcpy(blk, frame[i].data, RPMB_BLOCK_SIZE);
> + if (msync(blk, RPMB_BLOCK_SIZE, MS_SYNC) != 0) {
> + g_warning("%s: failed to sync update", __func__);
> + r->last_result = VIRTIO_RPMB_RES_WRITE_FAILURE;
> + break;
> + }
> + if (mprotect(blk, RPMB_BLOCK_SIZE, PROT_READ) != 0) {
> + g_warning("%s: failed to re-apply read protection",
> __func__);
> + r->last_result = VIRTIO_RPMB_RES_GENERAL_FAILURE;
> + break;
> + }
> + offset += RPMB_BLOCK_SIZE;
> + }
> + r->last_result = VIRTIO_RPMB_RES_OK;
> + extra_frames = i - 1;
> + }
> +
> + g_info("%s: %s (%x, %d extra frames processed), write_count=%d",
> __func__,
> + r->last_result == VIRTIO_RPMB_RES_OK ? "successful":"failed",
> + r->last_result, extra_frames, r->write_count);
> +
> + return extra_frames;
> +}
> +
> +
> /*
> * Return the result of the last message. This is only valid if the
> * previous message was VIRTIO_RPMB_REQ_PROGRAM_KEY or
> @@ -339,10 +430,14 @@ static struct virtio_rpmb_frame *
> vrpmb_handle_result_read(VuDev *dev)
> g_info("%s: for request:%x result:%x", __func__,
> r->last_reqresp, r->last_result);
>
> - if (r->last_reqresp == VIRTIO_RPMB_RESP_PROGRAM_KEY ||
> - r->last_reqresp == VIRTIO_RPMB_REQ_DATA_WRITE) {
> + if (r->last_reqresp == VIRTIO_RPMB_RESP_PROGRAM_KEY) {
> resp->result = htobe16(r->last_result);
> resp->req_resp = htobe16(r->last_reqresp);
> + } else if (r->last_reqresp == VIRTIO_RPMB_RESP_DATA_WRITE) {
> + resp->result = htobe16(r->last_result);
> + resp->req_resp = htobe16(r->last_reqresp);
> + resp->write_counter = htobe32(r->write_count);
> + resp->address = htobe16(r->last_address);
> } else {
> resp->result = htobe16(VIRTIO_RPMB_RES_GENERAL_FAILURE);
> }
> @@ -445,6 +540,10 @@ vrpmb_handle_ctrl(VuDev *dev, int qidx)
> __func__);
> }
> break;
> + case VIRTIO_RPMB_REQ_DATA_WRITE:
> + /* we can have multiple blocks handled */
> + n += vrpmb_handle_write(dev, f);
> + break;
> default:
> g_debug("un-handled request: %x", f->req_resp);
> break;
> --
> 2.20.1
>
--
Regards,
Joakim
- [RFC PATCH 03/19] hw/virtio: move virtio-pci.h into shared include space, (continued)
- [RFC PATCH 03/19] hw/virtio: move virtio-pci.h into shared include space, Alex Bennée, 2020/09/25
- [RFC PATCH 06/19] tools/vhost-user-rpmb: add boilerplate and initial main, Alex Bennée, 2020/09/25
- [RFC PATCH 07/19] tools/vhost-user-rpmb: implement --print-capabilities, Alex Bennée, 2020/09/25
- [RFC PATCH 08/19] tools/vhost-user-rpmb: connect to fd and instantiate basic run loop, Alex Bennée, 2020/09/25
- [RFC PATCH 09/19] tools/vhost-user-rpmb: add a --verbose/debug flags for logging, Alex Bennée, 2020/09/25
- [RFC PATCH 11/19] tools/vhost-user-rpmb: add --flash-path for backing store, Alex Bennée, 2020/09/25
- [RFC PATCH 12/19] tools/vhost-user-rpmb: import hmac_sha256 functions, Alex Bennée, 2020/09/25
- [RFC PATCH 10/19] tools/vhost-user-rpmb: handle shutdown and SIGINT/SIGHUP cleanly, Alex Bennée, 2020/09/25
- [RFC PATCH 17/19] tools/vhost-user-rpmb: add key persistence, Alex Bennée, 2020/09/25
- [RFC PATCH 15/19] tools/vhost-user-rpmb: implement VIRTIO_RPMB_REQ_DATA_WRITE, Alex Bennée, 2020/09/25
- Re: [RFC PATCH 15/19] tools/vhost-user-rpmb: implement VIRTIO_RPMB_REQ_DATA_WRITE,
Joakim Bech <=
- [RFC PATCH 16/19] tools/vhost-user-rpmb: implement VIRTIO_RPMB_REQ_DATA_READ, Alex Bennée, 2020/09/25
- [RFC PATCH 18/19] tools/vhost-user-rpmb: allow setting of the write_count, Alex Bennée, 2020/09/25
- [RFC PATCH 13/19] tools/vhost-user-rpmb: implement the PROGRAM_KEY handshake, Alex Bennée, 2020/09/25
- [RFC PATCH 19/19] docs: add a man page for vhost-user-rpmb, Alex Bennée, 2020/09/25
- [RFC PATCH 14/19] tools/vhost-user-rpmb: implement VIRTIO_RPMB_REQ_GET_WRITE_COUNTER, Alex Bennée, 2020/09/25
- Re: [RFC PATCH 00/19] vhost-user-rpmb (Replay Protected Memory Block), no-reply, 2020/09/25