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Fix name constraint bypasses for empty dNSName and quoted mailboxes #11948

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Fix name constraint bypasses for empty dNSName and quoted mailboxes #11948

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14 changes: 11 additions & 3 deletions src/x509.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6070,7 +6070,8 @@ static int MatchIpName(const char* name, int nameSz, WOLFSSL_GENERAL_NAME* gn)
/* Helper to check if name string matches a single GENERAL_NAME constraint.
* permitted selects subtree semantics for wildcard DNS names: containment
* for permitted subtrees, intersection for excluded subtrees.
* Returns 1 if matches, 0 if not. */
* Returns 1 if matches, 0 if not, and a negative error if the name cannot be
* compared, which the caller must treat as failing the constraint. */
static int MatchNameConstraint(int type, const char* name, int nameSz,
WOLFSSL_GENERAL_NAME* gn, int permitted)
{
Expand All @@ -6093,6 +6094,11 @@ static int MatchNameConstraint(int type, const char* name, int nameSz,
}
baseStr = (const char*)wolfSSL_ASN1_STRING_get0_data(gn->d.ia5);
baseLen = wolfSSL_ASN1_STRING_length(gn->d.ia5);
if (type == WOLFSSL_GEN_DNS && baseLen == 0) {
/* RFC 5280 4.2.1.10: an empty dNSName base covers every DNS
* name. */
return 1;
}
if (baseStr == NULL || baseLen <= 0) {
return 0;
}
Expand Down Expand Up @@ -6194,7 +6200,8 @@ int wolfSSL_NAME_CONSTRAINTS_check_name(WOLFSSL_NAME_CONSTRAINTS* nc,
}
hasPermittedType = 1;

if (MatchNameConstraint(type, name, nameSz, gn, 1)) {
/* A name that cannot be compared is not shown to be permitted. */
if (MatchNameConstraint(type, name, nameSz, gn, 1) == 1) {
matchedPermitted = 1;
break;
}
Expand All @@ -6221,7 +6228,8 @@ int wolfSSL_NAME_CONSTRAINTS_check_name(WOLFSSL_NAME_CONSTRAINTS* nc,
continue;
}

if (MatchNameConstraint(type, name, nameSz, gn, 0)) {
/* A name that cannot be compared is not shown to be outside. */
if (MatchNameConstraint(type, name, nameSz, gn, 0) != 0) {
WOLFSSL_MSG("Name in excluded subtrees");
return 0;
}
Expand Down
56 changes: 47 additions & 9 deletions tests/api/test_asn.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,14 @@
#include <wolfssl/wolfcrypt/asn_public.h>
#include <wolfssl/wolfcrypt/random.h>
#include <wolfssl/wolfcrypt/rsa.h>

/* A lone "." dNSName constraint base covers every DNS name, except with
* OPENSSL_COMPATIBLE_DEFAULTS where it matches no name. */
#ifdef OPENSSL_COMPATIBLE_DEFAULTS
#define NC_DNS_DOT_BASE_MATCH 0
#else
#define NC_DNS_DOT_BASE_MATCH 1
#endif
#ifdef HAVE_ED25519
#include <wolfssl/wolfcrypt/ed25519.h>
#endif
Expand Down Expand Up @@ -1054,12 +1062,24 @@ int test_wolfssl_local_MatchBaseName(void)
/* @ at end is invalid */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"user@", 5, ".domain.com", 11), 0);
/* double @ is invalid */
/* An '@' outside a quoted local-part cannot be compared */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"user@@domain.com", 16, ".domain.com", 11),
WC_NO_ERR_TRACE(ASN_PARSE_E));
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"user@domain@extra.com", 21, ".domain.com", 11),
WC_NO_ERR_TRACE(ASN_PARSE_E));
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"user@@domain.com", 16, ".domain.com", 11), 0);
/* multiple @ is invalid */
"user@domain@extra.com", 21, "extra.com", 9),
WC_NO_ERR_TRACE(ASN_PARSE_E));
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"user@domain@extra.com", 21, ".domain.com", 11), 0);
"x@evil.com@good.com", 19, "good.com", 8),
WC_NO_ERR_TRACE(ASN_PARSE_E));
/* RFC 5322 quoted local-part containing @ */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"\"x@y\"@evil.com", 14, "evil.com", 8), 1);
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"\"x@y\"@good.com", 14, "evil.com", 8), 0);
/* No @ in email name */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"userdomain.com", 14, ".domain.com", 11), 0);
Expand Down Expand Up @@ -1725,14 +1745,26 @@ int test_wolfssl_local_MatchBaseName(void)
/* Empty/zero size */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_DNS_TYPE,
"", 0, "domain.com", 10), 0);
/* RFC 5280 4.2.1.10: an empty dNSName base covers every DNS name. */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_DNS_TYPE,
"domain.com", 10, "", 0), 1);
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_DNS_TYPE,
"domain.com", 10, "", 0), 0);
"domain.com", 10, ".", 1), NC_DNS_DOT_BASE_MATCH);
ExpectIntEQ(wolfssl_local_MatchDnsConstraintWildcard(
"*.domain.com", 12, "", 0, 0), 1);
ExpectIntEQ(wolfssl_local_MatchDnsConstraintWildcard(
"*.domain.com", 12, ".", 1, 1), NC_DNS_DOT_BASE_MATCH);
/* An empty rfc822Name base names no host. */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_RFC822_TYPE,
"user@domain.com", 15, "", 0), 0);
/* Invalid type */
ExpectIntEQ(wolfssl_local_MatchBaseName(0xFF,
"domain.com", 10, "domain.com", 10), 0);
/* Name starting with dot */
/* Name starting with dot, whatever the base */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_DNS_TYPE,
".", 1, ".", 1), 0);
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_DNS_TYPE,
".domain.com", 11, "", 0), 0);
/* Name shorter than base */
ExpectIntEQ(wolfssl_local_MatchBaseName(ASN_DNS_TYPE,
"a.com", 5, "domain.com", 10), 0);
Expand Down Expand Up @@ -1858,13 +1890,16 @@ int test_wolfssl_local_MatchDnsConstraintWildcard(void)
NULL, 3, 1), 0);
ExpectIntEQ(wolfssl_local_MatchDnsConstraintWildcard("*.com", 0,
"com", 3, 1), 0);
/* A zero-length base covers every DNS name (RFC 5280 4.2.1.10). */
ExpectIntEQ(wolfssl_local_MatchDnsConstraintWildcard("*.com", 5,
"com", 0, 1), 0);
"com", 0, 1), 1);
/* Name beginning with a dot is invalid. */
ExpectIntEQ(dnsWildPermitted(".x.com", "com"), 0);
ExpectIntEQ(dnsWildExcluded(".x.com", "com"), 0);
/* Base that is only dots collapses to nothing. */
ExpectIntEQ(dnsWildExcluded("*.example.com", "."), 0);
/* A lone dot is the empty base unless OpenSSL compatible. */
ExpectIntEQ(dnsWildExcluded("*.example.com", "."),
NC_DNS_DOT_BASE_MATCH);
/* A base of more than one dot has an empty label. */
ExpectIntEQ(dnsWildExcluded("*.example.com", ".."), 0);
/* SAN has an empty interior label ("*..com"), but only the right-most
* "com" label overlaps the base "com" -- the empty label sits outside the
Expand Down Expand Up @@ -1892,6 +1927,9 @@ int test_wolfssl_local_MatchUriNameConstraint(void)
* Exact host match (no leading dot in the constraint).
*/
ExpectIntEQ(uriNC("https://host.com/path", "host.com"), 1);
/* A lone "." base is a leading-dot base with no labels. */
ExpectIntEQ(uriNC("https://host.com/path", "."),
NC_DNS_DOT_BASE_MATCH);
ExpectIntEQ(uriNC("https://host.com", "host.com"), 1);
ExpectIntEQ(uriNC("https://host.com:8443/x", "host.com"), 1);
ExpectIntEQ(uriNC("ftp://user@host.com/x", "host.com"), 1);
Expand Down
51 changes: 51 additions & 0 deletions tests/api/test_ossl_x509_ext.c
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,13 @@
#include <tests/api/api.h>
#include <tests/api/test_ossl_x509_ext.h>

/* A lone "." dNSName constraint base covers every DNS name, except with
* OPENSSL_COMPATIBLE_DEFAULTS where it matches no name. */
#ifdef OPENSSL_COMPATIBLE_DEFAULTS
#define NC_DNS_DOT_BASE_MATCH 0
#else
#define NC_DNS_DOT_BASE_MATCH 1
#endif

int test_wolfSSL_X509_get_extension_flags(void)
{
Expand Down Expand Up @@ -2367,6 +2374,12 @@ int test_wolfSSL_NAME_CONSTRAINTS_check_name(void)
/* @ at end */
ExpectIntEQ(wolfSSL_NAME_CONSTRAINTS_check_name(nc, GEN_EMAIL,
"user@", 5), 0);
/* An '@' outside a quoted local-part is not permitted */
ExpectIntEQ(wolfSSL_NAME_CONSTRAINTS_check_name(nc, GEN_EMAIL,
"x@evil.com@sub.wolfssl.com", 26), 0);
/* A quoted local-part may hold an '@' */
ExpectIntEQ(wolfSSL_NAME_CONSTRAINTS_check_name(nc, GEN_EMAIL,
"\"x@y\"@sub.wolfssl.com", 21), 1);
}

NAME_CONSTRAINTS_free(nc);
Expand Down Expand Up @@ -2436,6 +2449,44 @@ int test_wolfSSL_NAME_CONSTRAINTS_check_name(void)
"bar.example.com", 15), 1);
}

if (EXPECT_SUCCESS()) {
/* An empty excluded dNSName covers every DNS name (RFC 5280
* 4.2.1.10), as does a lone trailing dot unless OpenSSL
* compatible. */
GENERAL_SUBTREE* subtree = NULL;

ExpectNotNull(subtree =
wolfSSL_sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, 0));
if (EXPECT_SUCCESS()) {
ExpectIntEQ(wolfSSL_ASN1_STRING_set(subtree->base->d.ia5,
"", 0), WOLFSSL_SUCCESS);
}
ExpectIntEQ(wolfSSL_NAME_CONSTRAINTS_check_name(nc, GEN_DNS,
"evil.com", 8), 0);
ExpectIntEQ(wolfSSL_NAME_CONSTRAINTS_check_name(nc, GEN_DNS,
"*.evil.com", 10), 0);
if (EXPECT_SUCCESS()) {
ExpectIntEQ(wolfSSL_ASN1_STRING_set(subtree->base->d.ia5,
".", 1), WOLFSSL_SUCCESS);
}
ExpectIntEQ(wolfSSL_NAME_CONSTRAINTS_check_name(nc, GEN_DNS,
"evil.com", 8), !NC_DNS_DOT_BASE_MATCH);
}

if (EXPECT_SUCCESS()) {
/* Moved to the permitted side, an empty dNSName permits every DNS
* name. */
nc->permittedSubtrees = nc->excludedSubtrees;
nc->excludedSubtrees = NULL;
ExpectIntEQ(wolfSSL_ASN1_STRING_set(
wolfSSL_sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, 0)->
base->d.ia5, "", 0), WOLFSSL_SUCCESS);
ExpectIntEQ(wolfSSL_NAME_CONSTRAINTS_check_name(nc, GEN_DNS,
"any.example.org", 15), 1);
ExpectIntEQ(wolfSSL_NAME_CONSTRAINTS_check_name(nc, GEN_DNS,
"*.example.org", 13), 1);
}

NAME_CONSTRAINTS_free(nc);
nc = NULL;

Expand Down
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