[openssl-commits] [openssl] OpenSSL_1_0_2-stable update

[Matt Caswell]

The branch OpenSSL_1_0_2-stable has been updated
       via  44cbf6a9fe7db112ae2ed189412ab9e5205028b1 (commit)
      from  1aa0fcfb0a2bae287c2f26fe82d5b792fcc0cf3f (commit)


- Log -----------------------------------------------------------------
commit 44cbf6a9fe7db112ae2ed189412ab9e5205028b1
Author: Matt Caswell <matt at openssl.org>
Date:   Fri Oct 20 17:11:03 2017 +0100

    Don't use strcasecmp and strncasecmp for IA5 strings
    
    The functions strcasecmp() and strncasecmp() will use locale specific rules
    when performing comparison. This could cause some problems in certain
    locales. For example in the Turkish locale an 'I' character is not the
    uppercase version of 'i'. However IA5 strings should not use locale specific
    rules, i.e. for an IA5 string 'I' is uppercase 'i' even if using the
    Turkish locale.
    
    This fixes a bug in name constraints checking reported by Thomas Pornin
    (NCCGroup).
    
    This is not considered a security issue because it would require both a
    Turkish locale (or other locale with similar issues) and malfeasance by
    a trusted name-constrained CA for a certificate to pass name constraints
    in error. The constraints also have to be for excluded sub-trees which are
    extremely rare. Failure to match permitted subtrees is a bug, not a
    vulnerability.
    
    Reviewed-by: Richard Levitte <levitte at openssl.org>
    (Merged from https://github.com/openssl/openssl/pull/4570)

-----------------------------------------------------------------------

Summary of changes:
 crypto/x509v3/v3_ncons.c | 51 +++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 46 insertions(+), 5 deletions(-)

diff --git a/crypto/x509v3/v3_ncons.c b/crypto/x509v3/v3_ncons.c
index 2855269..1184091 100644
--- a/crypto/x509v3/v3_ncons.c
+++ b/crypto/x509v3/v3_ncons.c
@@ -107,6 +107,47 @@ ASN1_SEQUENCE(NAME_CONSTRAINTS) = {
 IMPLEMENT_ASN1_ALLOC_FUNCTIONS(GENERAL_SUBTREE)
 IMPLEMENT_ASN1_ALLOC_FUNCTIONS(NAME_CONSTRAINTS)
 
+/*
+ * We cannot use strncasecmp here because that applies locale specific rules.
+ * 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).
+ */
+static int ia5ncasecmp(const char *s1, const char *s2, size_t n)
+{
+    for (; n > 0; n--, s1++, s2++) {
+        if (*s1 != *s2) {
+            unsigned char c1 = (unsigned char)*s1, c2 = (unsigned char)*s2;
+
+            /* Convert to lower case */
+            if (c1 >= 0x41 /* A */ && c1 <= 0x5A /* Z */)
+                c1 += 0x20;
+            if (c2 >= 0x41 /* A */ && c2 <= 0x5A /* Z */)
+                c2 += 0x20;
+
+            if (c1 == c2)
+                continue;
+
+            if (c1 < c2)
+                return -1;
+
+            /* 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)
+{
+    /* No portable definition of SIZE_MAX, so we use (size_t)(-1) instead */
+    return ia5ncasecmp(s1, s2, (size_t)(-1));
+}
+
 static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
                                   X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval)
 {
@@ -384,7 +425,7 @@ static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)
             return X509_V_ERR_PERMITTED_VIOLATION;
     }
 
-    if (strcasecmp(baseptr, dnsptr))
+    if (ia5casecmp(baseptr, dnsptr))
         return X509_V_ERR_PERMITTED_VIOLATION;
 
     return X509_V_OK;
@@ -404,7 +445,7 @@ static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
     if (!baseat && (*baseptr == '.')) {
         if (eml->length > base->length) {
             emlptr += eml->length - base->length;
-            if (!strcasecmp(baseptr, emlptr))
+            if (ia5casecmp(baseptr, emlptr) == 0)
                 return X509_V_OK;
         }
         return X509_V_ERR_PERMITTED_VIOLATION;
@@ -425,7 +466,7 @@ static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
     }
     emlptr = emlat + 1;
     /* Just have hostname left to match: case insensitive */
-    if (strcasecmp(baseptr, emlptr))
+    if (ia5casecmp(baseptr, emlptr))
         return X509_V_ERR_PERMITTED_VIOLATION;
 
     return X509_V_OK;
@@ -464,14 +505,14 @@ static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
     if (*baseptr == '.') {
         if (hostlen > base->length) {
             p = hostptr + hostlen - base->length;
-            if (!strncasecmp(p, baseptr, base->length))
+            if (ia5ncasecmp(p, baseptr, base->length) == 0)
                 return X509_V_OK;
         }
         return X509_V_ERR_PERMITTED_VIOLATION;
     }
 
     if ((base->length != (int)hostlen)
-        || strncasecmp(hostptr, baseptr, hostlen))
+        || ia5ncasecmp(hostptr, baseptr, hostlen))
         return X509_V_ERR_PERMITTED_VIOLATION;
 
     return X509_V_OK;