Re: [kvm-unit-tests PATCH v3 5/5] s390x: uv-guest: Add attestation tests

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Tue, 22 Feb 2022 14:54:56 +0000
Steffen Eiden <seiden@linux.ibm.com> wrote:

> Adds several tests to verify correct error paths of attestation.
> 
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

in general looks good but I have several nits regarding the strings
used to report the tests

> ---
>  lib/s390x/asm/uv.h |   5 +-
>  s390x/uv-guest.c   | 193 ++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 196 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/s390x/asm/uv.h b/lib/s390x/asm/uv.h
> index c330c0f8..e5f7aa72 100644
> --- a/lib/s390x/asm/uv.h
> +++ b/lib/s390x/asm/uv.h
> @@ -108,7 +108,10 @@ struct uv_cb_qui {
>  	u8  reserved88[158 - 136];	/* 0x0088 */
>  	uint16_t max_guest_cpus;	/* 0x009e */
>  	u64 uv_feature_indications;	/* 0x00a0 */
> -	u8  reserveda8[200 - 168];	/* 0x00a8 */
> +	uint8_t  reserveda8[224 - 168];	/* 0x00a8 */
> +	uint64_t supp_att_hdr_ver;	/* 0x00e0 */
> +	uint64_t supp_paf;		/* 0x00e8 */
> +	uint8_t  reservedf0[256 - 240];	/* 0x00f0 */
>  }  __attribute__((packed))  __attribute__((aligned(8)));
>  
>  struct uv_cb_cgc {
> diff --git a/s390x/uv-guest.c b/s390x/uv-guest.c
> index 77057bd2..77edbba2 100644
> --- a/s390x/uv-guest.c
> +++ b/s390x/uv-guest.c
> @@ -2,10 +2,11 @@
>  /*
>   * Guest Ultravisor Call tests
>   *
> - * Copyright (c) 2020 IBM Corp
> + * Copyright IBM Corp. 2020, 2022
>   *
>   * Authors:
>   *  Janosch Frank <frankja@linux.ibm.com>
> + *  Steffen Eiden <seiden@linux.ibm.com>
>   */
>  
>  #include <libcflat.h>
> @@ -53,6 +54,15 @@ static void test_priv(void)
>  	check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION);
>  	report_prefix_pop();
>  
> +	report_prefix_push("attest");
> +	uvcb.cmd = UVC_CMD_ATTESTATION;
> +	uvcb.len = sizeof(struct uv_cb_attest);
> +	expect_pgm_int();
> +	enter_pstate();
> +	uv_call_once(0, (uint64_t)&uvcb);
> +	check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION);
> +	report_prefix_pop();
> +
>  	report_prefix_pop();
>  }
>  
> @@ -111,7 +121,187 @@ static void test_sharing(void)
>  	cc = uv_call(0, (u64)&uvcb);
>  	report(cc == 0 && uvcb.header.rc == UVC_RC_EXECUTED, "unshare");
>  	report_prefix_pop();
> +}
> +
> +#define ARCB_VERSION_NONE 0
> +#define ARCB_VERSION_1 0x0100
> +#define ARCB_MEAS_NONE 0
> +#define ARCB_MEAS_HMAC_SHA512 1
> +#define MEASUREMENT_SIZE_HMAC_SHA512 64
> +#define PAF_PHKH_ATT (1ULL << 61)
> +#define ADDITIONAL_SIZE_PAF_PHKH_ATT 32
> +/* arcb with one key slot and no nonce */
> +struct uv_arcb_v1 {
> +	uint64_t reserved0;		/* 0x0000 */
> +	uint32_t req_ver;		/* 0x0008 */
> +	uint32_t req_len;		/* 0x000c */
> +	uint8_t  iv[12];		/* 0x0010 */
> +	uint32_t reserved1c;		/* 0x001c */
> +	uint8_t  reserved20[7];		/* 0x0020 */
> +	uint8_t  nks;			/* 0x0027 */
> +	uint32_t reserved28;		/* 0x0028 */
> +	uint32_t sea;			/* 0x002c */
> +	uint64_t plaint_att_flags;	/* 0x0030 */
> +	uint32_t meas_alg_id;		/* 0x0038 */
> +	uint32_t reserved3c;		/* 0x003c */
> +	uint8_t  cpk[160];		/* 0x0040 */
> +	uint8_t  key_slot[80];		/* 0x00e0 */
> +	uint8_t  meas_key[64];		/* 0x0130 */
> +	uint8_t  tag[16];		/* 0x0170 */
> +} __attribute__((packed));
> +
> +struct attest_request_v1 {
> +	struct uv_arcb_v1 arcb;
> +	uint8_t measurement[MEASUREMENT_SIZE_HMAC_SHA512];
> +	uint8_t additional[ADDITIONAL_SIZE_PAF_PHKH_ATT];
> +};
> +
> +static void test_attest_v1(u64 supported_paf)
> +{
> +	struct uv_cb_attest uvcb = {
> +		.header.cmd = UVC_CMD_ATTESTATION,
> +		.header.len = sizeof(uvcb),
> +	};
> +	struct attest_request_v1 *attest_req = (void *)page;
> +	struct uv_arcb_v1 *arcb = &attest_req->arcb;
> +	int cc;
> +
> +	memset((void *)page, 0, PAGE_SIZE);
> +
> +	/*
> +	 * Create a minimal arcb/uvcb such that FW has everything to start
> +	 * unsealing the request. However, this unsealing will fail as the
> +	 * kvm-unit-test framework provides no cryptography functions that
> +	 * would be needed to seal such requests.
> +	 */
> +	arcb->req_ver = ARCB_VERSION_1;
> +	arcb->req_len = sizeof(*arcb);
> +	arcb->nks = 1;
> +	arcb->sea = sizeof(arcb->meas_key);
> +	arcb->plaint_att_flags = PAF_PHKH_ATT;
> +	arcb->meas_alg_id = ARCB_MEAS_HMAC_SHA512;
> +	uvcb.arcb_addr = (uint64_t)&attest_req->arcb;
> +	uvcb.measurement_address = (uint64_t)attest_req->measurement;
> +	uvcb.measurement_length = sizeof(attest_req->measurement);
> +	uvcb.add_data_address = (uint64_t)attest_req->additional;
> +	uvcb.add_data_length = sizeof(attest_req->additional);
> +
> +	uvcb.continuation_token = 0xff;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0101, "invalid continuation token");
> +	uvcb.continuation_token = 0;
> +
> +	uvcb.user_data_length = sizeof(uvcb.user_data) + 1;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0102, "invalid user data size");
> +	uvcb.user_data_length = 0;
> +
> +	uvcb.arcb_addr = get_ram_size() + PAGE_SIZE;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0103, "invalid address arcb");
> +	uvcb.arcb_addr = page;
> +
> +	/* 0104 - 0105 need an unseal-able request */
> +
> +	arcb->req_ver = ARCB_VERSION_NONE;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0106, "unsupported version");
> +	arcb->req_ver = ARCB_VERSION_1;
> +
> +	arcb->req_len += 1;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0107, "invalid arcb size 1");

I would like a more descriptive string for the report message.
something like "arcb too big"

> +	arcb->req_len -= 1;
> +
> +	/*
> +	 * The arcb needs to grow as well if number of key slots (nks)
> +	 * is increased. However, this is not the case and there is no explicit
> +	 * 'too many/less nks for that arcb size' error code -> expect 0x0107
> +	 */
> +	arcb->nks = 2;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0107, "invalid arcb size 2");

and here maybe something like "arcb too small for nks" or "too many nks
for arcb"

> +	arcb->nks = 1;
> +
> +	arcb->nks = 0;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0108, "invalid num key slots");
> +	arcb->nks = 1;
> +
> +	/*
> +	 * Possible valid size (when using nonce).
> +	 * However, req_len too small to host a nonce
> +	 */
> +	arcb->sea = 80;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0109, "invalid encrypted size 1");

"encrypted size too big" (if I understand correctly)

> +	arcb->sea = 17;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x0109, "invalid encrypted size 2");

"encrypted size too small" (if I understand correctly)

> +	arcb->sea = 64;
> +
> +	arcb->plaint_att_flags = supported_paf ^ GENMASK_ULL(63, 0);
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x010a, "invalid flag");
> +	arcb->plaint_att_flags = PAF_PHKH_ATT;
> +
> +	arcb->meas_alg_id = ARCB_MEAS_NONE;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x010b, "invalid measurement algorithm");
> +	arcb->meas_alg_id = ARCB_MEAS_HMAC_SHA512;
>  
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x010c, "unable unseal");
> +
> +	uvcb.measurement_length = 0;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x010d, "invalid measurement size");
> +	uvcb.measurement_length = sizeof(attest_req->measurement);
> +
> +	uvcb.add_data_length = 0;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc == 1 && uvcb.header.rc == 0x010e, "invalid additional size");
> +	uvcb.add_data_length = sizeof(attest_req->additional);
> +}
> +
> +static void test_attest(void)
> +{
> +	struct uv_cb_attest uvcb = {
> +		.header.cmd = UVC_CMD_ATTESTATION,
> +		.header.len = sizeof(uvcb),
> +	};
> +	const struct uv_cb_qui *uvcb_qui = uv_get_query_data();
> +	int cc;
> +
> +	report_prefix_push("attest");
> +
> +	if (!uv_query_test_call(BIT_UVC_CMD_ATTESTATION)) {
> +		report_skip("Attestation not supported.");
> +		goto done;
> +	}
> +
> +	/* Verify that the UV supports at least one header version */
> +	report(uvcb_qui->supp_att_hdr_ver, "has hdr support");
> +
> +	memset((void *)page, 0, PAGE_SIZE);
> +
> +	uvcb.header.len -= 1;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc && uvcb.header.rc == UVC_RC_INV_LEN, "invalid uvcb size 1");

"uvcb too small"

> +	uvcb.header.len += 1;
> +
> +	uvcb.header.len += 1;
> +	cc = uv_call(0, (uint64_t)&uvcb);
> +	report(cc && uvcb.header.rc == UVC_RC_INV_LEN, "invalid uvcb size 2");

"uvcb too large"

> +	uvcb.header.len -= 1;
> +
> +	report_prefix_push("v1");
> +	if (test_bit_inv(0, &uvcb_qui->supp_att_hdr_ver))
> +		test_attest_v1(uvcb_qui->supp_paf);
> +	else
> +		report_skip("Attestation version 1 not supported");
> +	report_prefix_pop();
> +done:
>  	report_prefix_pop();
>  }
>  
> @@ -193,6 +383,7 @@ int main(void)
>  	test_invalid();
>  	test_query();
>  	test_sharing();
> +	test_attest();
>  	free_page((void *)page);
>  done:
>  	report_prefix_pop();