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Remove BASIC_CONSTRAINTS_STRING_FALSE_CASE2 #3422

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Remove BASIC_CONSTRAINTS_STRING_FALSE_CASE2 #3422

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49 changes: 16 additions & 33 deletions library/spdm_crypt_lib/libspdm_crypt_cert.c
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Original file line number Diff line number Diff line change
Expand Up @@ -156,14 +156,13 @@
#define ALGO_SLHDSA_SHAKE_256F_OID {0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x03, 0x1F}
#endif

/*leaf cert basic_constraints false case1: CA: false and CA object is excluded */
#define BASIC_CONSTRAINTS_STRING_FALSE_CASE1 {0x30, 0x00}
/* Leaf certificate basic constraints with cA field set to false. According to RFC5280, false is the
* default value, and according to DER encoding a sequence item with a default value must not be
* encoded. */
#define BASIC_CONSTRAINTS_CA_FALSE {0x30, 0x00}

/*leaf cert basic_constraints false case2: CA: false */
#define BASIC_CONSTRAINTS_STRING_FALSE_CASE2 {0x30, 0x03, 0x01, 0x01, 0x00}

/*leaf cert basic_constraints true case: CA: true */
#define BASIC_CONSTRAINTS_STRING_TRUE_CASE {0x30, 0x03, 0x01, 0x01, 0xFF}
/* Leaf certificate basic constraints with cA field set to true. */
#define BASIC_CONSTRAINTS_CA_TRUE {0x30, 0x03, 0x01, 0x01, 0xFF}

/**
* Retrieve the asymmetric public key from one DER-encoded X509 certificate.
Expand Down Expand Up @@ -1129,8 +1128,7 @@ static bool libspdm_verify_leaf_cert_basic_constraints(const uint8_t *cert, size
uint8_t cert_basic_constraints[LIBSPDM_MAX_BASIC_CONSTRAINTS_CA_LEN];
size_t len;

uint8_t basic_constraints_false_case1[] = BASIC_CONSTRAINTS_STRING_FALSE_CASE1;
uint8_t basic_constraints_false_case2[] = BASIC_CONSTRAINTS_STRING_FALSE_CASE2;
uint8_t basic_constraints_false_case[] = BASIC_CONSTRAINTS_CA_FALSE;

len = LIBSPDM_MAX_BASIC_CONSTRAINTS_CA_LEN;

Expand All @@ -1147,17 +1145,10 @@ static bool libspdm_verify_leaf_cert_basic_constraints(const uint8_t *cert, size
}
}

if ((len == sizeof(basic_constraints_false_case1)) &&
(libspdm_consttime_is_mem_equal(cert_basic_constraints,
basic_constraints_false_case1,
sizeof(basic_constraints_false_case1)))) {
return true;
}

if ((len == sizeof(basic_constraints_false_case2)) &&
if ((len == sizeof(basic_constraints_false_case)) &&
(libspdm_consttime_is_mem_equal(cert_basic_constraints,
basic_constraints_false_case2,
sizeof(basic_constraints_false_case2)))) {
basic_constraints_false_case,
sizeof(basic_constraints_false_case)))) {
return true;
}

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@jcahill0 jcahill0 Dec 9, 2025

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If I'm reading commit a9e42b0 correctly, then it appears this would trigger a "false"/failure of any existing/previous deployed leaf certificate with the Basic Constraints OID's CA:FALSE (len!=sizeof(basic_constraints_false_case fallout case), which libspdm_verify_leaf_cert_basic_constraints() used to pass.

Could the empty CA:FALSE check be made optional for SPDM Requesters that choose to handle this case?

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@steven-bellock steven-bellock Dec 9, 2025

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Could the empty CA:FALSE check be made optional for SPDM Requesters that choose to handle this case?

#3164 (comment) proposes to let the Integrator selectively disable specific checks, so when/if that gets implemented then they would be able to disable the Basic Constraints check if they so desire.

Expand Down Expand Up @@ -1193,9 +1184,8 @@ static bool libspdm_verify_set_cert_leaf_cert_basic_constraints(
uint8_t cert_basic_constraints[LIBSPDM_MAX_BASIC_CONSTRAINTS_CA_LEN];
size_t len;

const uint8_t basic_constraints_false_case1[] = BASIC_CONSTRAINTS_STRING_FALSE_CASE1;
const uint8_t basic_constraints_false_case2[] = BASIC_CONSTRAINTS_STRING_FALSE_CASE2;
const uint8_t basic_constraints_true_case[] = BASIC_CONSTRAINTS_STRING_TRUE_CASE;
const uint8_t basic_constraints_false_case[] = BASIC_CONSTRAINTS_CA_FALSE;
const uint8_t basic_constraints_true_case[] = BASIC_CONSTRAINTS_CA_TRUE;

len = LIBSPDM_MAX_BASIC_CONSTRAINTS_CA_LEN;

Expand All @@ -1210,17 +1200,10 @@ static bool libspdm_verify_set_cert_leaf_cert_basic_constraints(
if ((cert_model == SPDM_CERTIFICATE_INFO_CERT_MODEL_DEVICE_CERT) ||
(cert_model == SPDM_CERTIFICATE_INFO_CERT_MODEL_GENERIC_CERT)) {
if (need_basic_constraints || (len != 0)) {
if ((len == sizeof(basic_constraints_false_case1)) &&
(libspdm_consttime_is_mem_equal(cert_basic_constraints,
basic_constraints_false_case1,
sizeof(basic_constraints_false_case1)))) {
return true;
}

if ((len == sizeof(basic_constraints_false_case2)) &&
if ((len == sizeof(basic_constraints_false_case)) &&
(libspdm_consttime_is_mem_equal(cert_basic_constraints,
basic_constraints_false_case2,
sizeof(basic_constraints_false_case2)))) {
basic_constraints_false_case,
sizeof(basic_constraints_false_case)))) {
return true;
}
}
Expand Down Expand Up @@ -1815,7 +1798,7 @@ bool libspdm_is_root_certificate(const uint8_t *cert, size_t cert_size)
bool result;
uint8_t cert_basic_constraints[LIBSPDM_MAX_BASIC_CONSTRAINTS_CA_LEN];
size_t cert_basic_constraints_len;
const uint8_t basic_constraints_true_case[] = BASIC_CONSTRAINTS_STRING_TRUE_CASE;
const uint8_t basic_constraints_true_case[] = BASIC_CONSTRAINTS_CA_TRUE;

if (cert == NULL || cert_size == 0) {
return false;
Expand Down