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openssl/backport-Fix-the-name-constraints-code-to-not-assume-NUL-term.patch
Steven.YGui 36a31cca2d backport upstream patches
2021-12-25 18:00:50 +08:00

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From 8393de42498f8be75cf0353f5c9f906a43a748d2 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Wed, 18 Aug 2021 17:08:58 +0100
Subject: [PATCH] Fix the name constraints code to not assume NUL terminated
strings
ASN.1 strings may not be NUL terminated. Don't assume they are.
CVE-2021-3712
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
---
crypto/x509v3/v3_ncons.c | 77 +++++++++++++++++++++++++++-------------
1 file changed, 52 insertions(+), 25 deletions(-)
diff --git a/crypto/x509v3/v3_ncons.c b/crypto/x509v3/v3_ncons.c
index 2a7b4f0992..cb701c4d84 100644
--- a/crypto/x509v3/v3_ncons.c
+++ b/crypto/x509v3/v3_ncons.c
@@ -63,8 +63,31 @@ ASN1_SEQUENCE(NAME_CONSTRAINTS) = {
IMPLEMENT_ASN1_ALLOC_FUNCTIONS(GENERAL_SUBTREE)
IMPLEMENT_ASN1_ALLOC_FUNCTIONS(NAME_CONSTRAINTS)
+
+#define IA5_OFFSET_LEN(ia5base, offset) \
+ ((ia5base)->length - ((unsigned char *)(offset) - (ia5base)->data))
+
+/* Like memchr but for ASN1_IA5STRING. Additionally you can specify the
+ * starting point to search from
+ */
+# define ia5memchr(str, start, c) memchr(start, c, IA5_OFFSET_LEN(str, start))
+
+/* Like memrrchr but for ASN1_IA5STRING */
+static char *ia5memrchr(ASN1_IA5STRING *str, int c)
+{
+ int i;
+
+ for (i = str->length; i > 0 && str->data[i - 1] != c; i--);
+
+ if (i == 0)
+ return NULL;
+
+ return (char *)&str->data[i - 1];
+}
+
/*
- * We cannot use strncasecmp here because that applies locale specific rules.
+ * We cannot use strncasecmp here because that applies locale specific rules. It
+ * also doesn't work with ASN1_STRINGs that may have embedded NUL characters.
* For example in Turkish 'I' is not the uppercase character for 'i'. We need to
* do a simple ASCII case comparison ignoring the locale (that is why we use
* numeric constants below).
@@ -89,20 +112,12 @@ static int ia5ncasecmp(const char *s1, const char *s2, size_t n)
/* c1 > c2 */
return 1;
- } else if (*s1 == 0) {
- /* If we get here we know that *s2 == 0 too */
- return 0;
}
}
return 0;
}
-static int ia5casecmp(const char *s1, const char *s2)
-{
- return ia5ncasecmp(s1, s2, SIZE_MAX);
-}
-
static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval)
{
@@ -337,7 +352,7 @@ static int cn2dnsid(ASN1_STRING *cn, unsigned char **dnsid, size_t *idlen)
--utf8_length;
/* Reject *embedded* NULs */
- if ((size_t)utf8_length != strlen((char *)utf8_value)) {
+ if (memchr(utf8_value, 0, utf8_length) != NULL) {
OPENSSL_free(utf8_value);
return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
}
@@ -536,9 +551,14 @@ static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)
{
char *baseptr = (char *)base->data;
char *dnsptr = (char *)dns->data;
+
/* Empty matches everything */
- if (!*baseptr)
+ if (base->length == 0)
return X509_V_OK;
+
+ if (dns->length < base->length)
+ return X509_V_ERR_PERMITTED_VIOLATION;
+
/*
* Otherwise can add zero or more components on the left so compare RHS
* and if dns is longer and expect '.' as preceding character.
@@ -549,7 +569,7 @@ static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)
return X509_V_ERR_PERMITTED_VIOLATION;
}
- if (ia5casecmp(baseptr, dnsptr))
+ if (ia5ncasecmp(baseptr, dnsptr, base->length))
return X509_V_ERR_PERMITTED_VIOLATION;
return X509_V_OK;
@@ -560,16 +580,17 @@ static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
{
const char *baseptr = (char *)base->data;
const char *emlptr = (char *)eml->data;
+ const char *baseat = ia5memrchr(base, '@');
+ const char *emlat = ia5memrchr(eml, '@');
+ size_t basehostlen, emlhostlen;
- const char *baseat = strchr(baseptr, '@');
- const char *emlat = strchr(emlptr, '@');
if (!emlat)
return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
/* Special case: initial '.' is RHS match */
- if (!baseat && (*baseptr == '.')) {
+ if (!baseat && base->length > 0 && (*baseptr == '.')) {
if (eml->length > base->length) {
emlptr += eml->length - base->length;
- if (ia5casecmp(baseptr, emlptr) == 0)
+ if (ia5ncasecmp(baseptr, emlptr, base->length) == 0)
return X509_V_OK;
}
return X509_V_ERR_PERMITTED_VIOLATION;
@@ -589,8 +610,10 @@ static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
baseptr = baseat + 1;
}
emlptr = emlat + 1;
+ basehostlen = IA5_OFFSET_LEN(base, baseptr);
+ emlhostlen = IA5_OFFSET_LEN(eml, emlptr);
/* Just have hostname left to match: case insensitive */
- if (ia5casecmp(baseptr, emlptr))
+ if (basehostlen != emlhostlen || ia5ncasecmp(baseptr, emlptr, emlhostlen))
return X509_V_ERR_PERMITTED_VIOLATION;
return X509_V_OK;
@@ -601,10 +624,14 @@ static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
{
const char *baseptr = (char *)base->data;
const char *hostptr = (char *)uri->data;
- const char *p = strchr(hostptr, ':');
+ const char *p = ia5memchr(uri, (char *)uri->data, ':');
int hostlen;
+
/* Check for foo:// and skip past it */
- if (!p || (p[1] != '/') || (p[2] != '/'))
+ if (p == NULL
+ || IA5_OFFSET_LEN(uri, p) < 3
+ || p[1] != '/'
+ || p[2] != '/')
return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
hostptr = p + 3;
@@ -612,13 +639,13 @@ static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
/* Look for a port indicator as end of hostname first */
- p = strchr(hostptr, ':');
+ p = ia5memchr(uri, hostptr, ':');
/* Otherwise look for trailing slash */
- if (!p)
- p = strchr(hostptr, '/');
+ if (p == NULL)
+ p = ia5memchr(uri, hostptr, '/');
- if (!p)
- hostlen = strlen(hostptr);
+ if (p == NULL)
+ hostlen = IA5_OFFSET_LEN(uri, hostptr);
else
hostlen = p - hostptr;
@@ -626,7 +653,7 @@ static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
/* Special case: initial '.' is RHS match */
- if (*baseptr == '.') {
+ if (base->length > 0 && *baseptr == '.') {
if (hostlen > base->length) {
p = hostptr + hostlen - base->length;
if (ia5ncasecmp(p, baseptr, base->length) == 0)
--
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