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NameConstraints: support wildcard SAN

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This commit is contained in:
Marco Oliverio
2026-05-28 09:57:01 +02:00
parent 2dd7947d27
commit c4b4e6cd14
5 changed files with 623 additions and 8 deletions
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tests/api.c
+167
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@@ -24480,6 +24480,172 @@ static int test_NameConstraints_OtherName(void)
return EXPECT_RESULT();
}
#if defined(WOLFSSL_ASN_TEMPLATE) && \
defined(WOLFSSL_CERT_REQ) && !defined(NO_ASN_TIME) && \
defined(WOLFSSL_CERT_GEN) && defined(HAVE_ECC) && \
defined(WOLFSSL_CERT_EXT) && !defined(NO_CERTS) && \
defined(WOLFSSL_ALT_NAMES) && defined(WOLFSSL_CUSTOM_OID) && \
defined(HAVE_OID_ENCODING) && !defined(IGNORE_NAME_CONSTRAINTS)
/* Build a SubjectAltName extension value with a single GeneralName of the
* given context tag (0x82 dnsName, 0x86 URI) carrying `val`. */
static word32 build_simple_san(byte* out, word32 outSz, byte gnTag,
const char* val)
{
word32 vlen = (word32)XSTRLEN(val);
if (vlen > 0x7F || outSz < vlen + 4)
return 0;
out[0] = 0x30; /* SEQUENCE */
out[1] = (byte)(vlen + 2);
out[2] = gnTag; /* [tag] GeneralName */
out[3] = (byte)vlen;
XMEMCPY(out + 4, val, vlen);
return vlen + 4;
}
/* Build a NameConstraints extension value with a single subtree ([0]
* permitted or [1] excluded) carrying a GeneralName of context tag `gnTag`
* with value `val`. */
static word32 build_simple_nameConstraints(byte* out, word32 outSz,
int excluded, byte gnTag, const char* val)
{
word32 vlen = (word32)XSTRLEN(val);
word32 n3 = vlen + 2; /* GeneralSubtree content: the base GN */
word32 n2 = n3 + 2; /* subtrees list content: one GeneralSubtree */
word32 n1 = n2 + 2; /* SEQUENCE content: the subtrees list */
if (vlen > 0x7F || outSz < n1 + 2)
return 0;
out[0] = 0x30; /* SEQUENCE */
out[1] = (byte)n1;
out[2] = excluded ? 0xA1 : 0xA0; /* [1] excluded / [0] permitted */
out[3] = (byte)n2;
out[4] = 0x30; /* GeneralSubtree */
out[5] = (byte)n3;
out[6] = gnTag; /* base GeneralName */
out[7] = (byte)vlen;
XMEMCPY(out + 8, val, vlen);
return n1 + 2;
}
#endif
/* End-to-end enforcement of DNS and URI nameConstraints against wildcard and
* sub-host leaf SANs, exercised through the real chain-verification path.
*
* DNS subtree semantics (RFC 5280 4.2.1.10) plus wildcard reasoning:
* - excluded DNS:foo.example.com must reject a leaf SAN *.example.com,
* because the wildcard can expand to the excluded host (security gap).
* - permitted DNS:example.com must accept *.example.com (contained), while
* permitted DNS:foo.example.com must reject it (the wildcard can escape).
* URI semantics: a constraint without a leading dot is an EXACT host match,
* not a subtree, so permitted URI:host.com must reject https://www.host.com/.
*/
static int test_NameConstraints_DnsUriWildcard(void)
{
EXPECT_DECLS;
#if defined(WOLFSSL_ASN_TEMPLATE) && \
defined(WOLFSSL_CERT_REQ) && !defined(NO_ASN_TIME) && \
defined(WOLFSSL_CERT_GEN) && defined(HAVE_ECC) && \
defined(WOLFSSL_CERT_EXT) && !defined(NO_CERTS) && \
defined(WOLFSSL_ALT_NAMES) && defined(WOLFSSL_CUSTOM_OID) && \
defined(HAVE_OID_ENCODING) && !defined(IGNORE_NAME_CONSTRAINTS)
byte nc[64];
byte san[64];
word32 ncSz, sanSz;
const byte DNS = 0x82; /* [2] dnsName */
const byte URI = 0x86; /* [6] uniformResourceIdentifier */
/* --- DNS, excluded subtree --- */
/* (1) Excluded foo.example.com vs wildcard SAN that can reach it: the
* pre-fix byte-length guard let this through. Must reject. */
ncSz = build_simple_nameConstraints(nc, sizeof(nc), 1, DNS,
"foo.example.com");
sanSz = build_simple_san(san, sizeof(san), DNS, "*.example.com");
ExpectIntGT((int)ncSz, 0);
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz),
WC_NO_ERR_TRACE(ASN_NAME_INVALID_E));
/* (2) Positive control: same exclusion, wildcard in a different domain
* cannot reach foo.example.com -> accept. */
sanSz = build_simple_san(san, sizeof(san), DNS, "*.other.com");
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz), 0);
/* (3) Regression: literal SAN inside the excluded subtree still rejects. */
sanSz = build_simple_san(san, sizeof(san), DNS, "foo.example.com");
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz),
WC_NO_ERR_TRACE(ASN_NAME_INVALID_E));
/* (4) Regression: literal SAN outside the excluded subtree accepts. */
sanSz = build_simple_san(san, sizeof(san), DNS, "bar.other.com");
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz), 0);
/* --- DNS, permitted subtree --- */
/* (5) Permitted example.com accepts *.example.com (fully contained). */
ncSz = build_simple_nameConstraints(nc, sizeof(nc), 0, DNS, "example.com");
sanSz = build_simple_san(san, sizeof(san), DNS, "*.example.com");
ExpectIntGT((int)ncSz, 0);
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz), 0);
/* (6) Permitted foo.example.com rejects *.example.com (the wildcard can
* expand outside the permitted subtree). */
ncSz = build_simple_nameConstraints(nc, sizeof(nc), 0, DNS,
"foo.example.com");
sanSz = build_simple_san(san, sizeof(san), DNS, "*.example.com");
ExpectIntGT((int)ncSz, 0);
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz),
WC_NO_ERR_TRACE(ASN_NAME_INVALID_E));
/* --- URI, exact-host vs subtree semantics --- */
/* (7) Permitted URI host.com (no leading dot) is an EXACT host match:
* a sub-host URI is NOT contained -> reject. Pre-fix this wrongly
* subtree-matched and accepted. */
ncSz = build_simple_nameConstraints(nc, sizeof(nc), 0, URI, "host.com");
sanSz = build_simple_san(san, sizeof(san), URI, "https://www.host.com/");
ExpectIntGT((int)ncSz, 0);
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz),
WC_NO_ERR_TRACE(ASN_NAME_INVALID_E));
/* (8) Permitted URI host.com accepts the exact host. */
sanSz = build_simple_san(san, sizeof(san), URI, "https://host.com/path");
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz), 0);
/* (9) Permitted URI .host.com (leading dot) is a subtree: the sub-host is
* accepted but the bare host is not. */
ncSz = build_simple_nameConstraints(nc, sizeof(nc), 0, URI, ".host.com");
sanSz = build_simple_san(san, sizeof(san), URI, "https://www.host.com/");
ExpectIntGT((int)ncSz, 0);
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz), 0);
sanSz = build_simple_san(san, sizeof(san), URI, "https://host.com/");
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz),
WC_NO_ERR_TRACE(ASN_NAME_INVALID_E));
/* (10) Excluded URI host.com (exact): bare host excluded, sub-host not. */
ncSz = build_simple_nameConstraints(nc, sizeof(nc), 1, URI, "host.com");
sanSz = build_simple_san(san, sizeof(san), URI, "https://host.com/");
ExpectIntGT((int)ncSz, 0);
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz),
WC_NO_ERR_TRACE(ASN_NAME_INVALID_E));
sanSz = build_simple_san(san, sizeof(san), URI, "https://www.host.com/");
ExpectIntGT((int)sanSz, 0);
ExpectIntEQ(verify_with_otherName_chain(nc, ncSz, 1, san, sanSz), 0);
#endif
return EXPECT_RESULT();
}
static int test_MakeCertWithCaFalse(void)
{
EXPECT_DECLS;
@@ -40240,6 +40406,7 @@ TEST_CASE testCases[] = {
TEST_DECL(test_PathLenSelfIssuedAllowed),
TEST_DECL(test_PathLenNoKeyUsage),
TEST_DECL(test_NameConstraints_OtherName),
TEST_DECL(test_NameConstraints_DnsUriWildcard),
TEST_DECL(test_ParseSerial0FixtureMatrix),
TEST_DECL(test_MakeCertWithCaFalse),
#ifdef WOLFSSL_CERT_SIGN_CB