Bring in functions used by stunnel and exim from BoringSSL - this brings

in X509_check_host, X509_check_email, X509_check_ip, and X509_check_ip_asc,
with some cleanup on the way in by myself and jsing@
ok bcook@

2 files changed, 452 insertions, 2 deletions

diff --git a/src/lib/libcrypto/x509v3/v3_utl.c b/src/lib/libcrypto/x509v3/v3_utl.c
index ee135a0b52..7516cd3c20 100644
--- a/src/lib/libcrypto/x509v3/v3_utl.c
+++ b/src/lib/libcrypto/x509v3/v3_utl.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: v3_utl.c,v 1.24 2015/02/07 13:19:15 doug Exp $ */
+/* $OpenBSD: v3_utl.c,v 1.25 2016/09/03 11:56:33 beck Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project.
  */
@@ -638,6 +638,429 @@ X509_email_free(STACK_OF(OPENSSL_STRING) *sk)
         sk_OPENSSL_STRING_pop_free(sk, str_free);
 }
 
+typedef int (*equal_fn) (const unsigned char *pattern, size_t pattern_len,
+    const unsigned char *subject, size_t subject_len, unsigned int flags);
+
+/* Skip pattern prefix to match "wildcard" subject */
+static void skip_prefix(const unsigned char **p, size_t *plen,
+    const unsigned char *subject, size_t subject_len, unsigned int flags)
+{
+        const unsigned char *pattern = *p;
+        size_t pattern_len = *plen;
+
+        /*
+         * If subject starts with a leading '.' followed by more octets, and
+         * pattern is longer, compare just an equal-length suffix with the
+         * full subject (starting at the '.'), provided the prefix contains
+         * no NULs.
+         */
+        if ((flags & _X509_CHECK_FLAG_DOT_SUBDOMAINS) == 0)
+                return;
+
+        while (pattern_len > subject_len && *pattern) {
+                if ((flags & X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS) &&
+                    *pattern == '.')
+                        break;
+                ++pattern;
+                --pattern_len;
+        }
+
+        /* Skip if entire prefix acceptable */
+        if (pattern_len == subject_len) {
+                *p = pattern;
+                *plen = pattern_len;
+        }
+}
+
+/*
+ * Open/BoringSSL uses memcmp for "equal_case" while their
+ * "equal_nocase" function is a hand-rolled strncasecmp that does not
+ * allow \0 in the pattern. Since an embedded \0 is likely a sign of
+ * problems, we simply don't allow it in either case, and then we use
+ * standard libc funcitons.
+ */
+
+/* Compare using strncasecmp */
+static int equal_nocase(const unsigned char *pattern, size_t pattern_len,
+    const unsigned char *subject, size_t subject_len,
+    unsigned int flags)
+{
+        if (memchr(pattern, '\0', pattern_len) != NULL)
+                return 0;
+        if (memchr(subject, '\0', subject_len) != NULL)
+                return 0;
+        skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
+        if (pattern_len != subject_len)
+                return 0;
+        return (strncasecmp(pattern, subject, pattern_len) == 0);
+}
+
+/* Compare using strncmp. */
+static int equal_case(const unsigned char *pattern, size_t pattern_len,
+    const unsigned char *subject, size_t subject_len,
+    unsigned int flags)
+{
+        if (memchr(pattern, 0, pattern_len) != NULL)
+                return 0;
+        if (memchr(subject, 0, subject_len) != NULL)
+                return 0;
+        skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
+        if (pattern_len != subject_len)
+                return 0;
+        return (strncmp(pattern, subject, pattern_len) == 0);
+}
+
+/*
+ * RFC 5280, section 7.5, requires that only the domain is compared in a
+ * case-insensitive manner.
+ */
+static int equal_email(const unsigned char *a, size_t a_len,
+    const unsigned char *b, size_t b_len,
+    unsigned int unused_flags)
+{
+        size_t pos = a_len;
+        if (a_len != b_len)
+                return 0;
+        /*
+         * We search backwards for the '@' character, so that we do not have to
+         * deal with quoted local-parts.  The domain part is compared in a
+         * case-insensitive manner.
+         */
+        while (pos > 0) {
+                pos--;
+                if (a[pos] == '@' || b[pos] == '@') {
+                        if (!equal_nocase(a + pos, a_len - pos, b + pos, a_len - pos, 0))
+                                return 0;
+                        break;
+                }
+        }
+        if (pos == 0)
+                pos = a_len;
+        return equal_case(a, pos, b, pos, 0);
+}
+
+/*
+ * Compare the prefix and suffix with the subject, and check that the
+ * characters in-between are valid.
+ */
+static int wildcard_match(const unsigned char *prefix, size_t prefix_len,
+    const unsigned char *suffix, size_t suffix_len,
+    const unsigned char *subject, size_t subject_len, unsigned int flags)
+{
+        const unsigned char *wildcard_start;
+        const unsigned char *wildcard_end;
+        const unsigned char *p;
+        int allow_multi = 0;
+        int allow_idna = 0;
+
+        if (subject_len < prefix_len + suffix_len)
+                return 0;
+        if (!equal_nocase(prefix, prefix_len, subject, prefix_len, flags))
+                return 0;
+        wildcard_start = subject + prefix_len;
+        wildcard_end = subject + (subject_len - suffix_len);
+        if (!equal_nocase(wildcard_end, suffix_len, suffix, suffix_len, flags))
+                return 0;
+        /*
+         * If the wildcard makes up the entire first label, it must match at
+         * least one character.
+         */
+        if (prefix_len == 0 && *suffix == '.') {
+                if (wildcard_start == wildcard_end)
+                        return 0;
+                allow_idna = 1;
+                if (flags & X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS)
+                        allow_multi = 1;
+        }
+        /* IDNA labels cannot match partial wildcards */
+        if (!allow_idna &&
+            subject_len >= 4
+            && strncasecmp((char *)subject, "xn--", 4) == 0)
+                return 0;
+        /* The wildcard may match a literal '*' */
+        if (wildcard_end == wildcard_start + 1 && *wildcard_start == '*')
+                return 1;
+        /*
+         * Check that the part matched by the wildcard contains only
+         * permitted characters and only matches a single label unless
+         * allow_multi is set.
+         */
+        for (p = wildcard_start; p != wildcard_end; ++p)
+                if (!(('0' <= *p && *p <= '9') || ('A' <= *p && *p <= 'Z') ||
+                    ('a' <= *p && *p <= 'z') || *p == '-' ||
+                    (allow_multi && *p == '.')))
+                        return 0;
+        return 1;
+}
+
+#define LABEL_START     (1 << 0)
+#define LABEL_END       (1 << 1)
+#define LABEL_HYPHEN    (1 << 2)
+#define LABEL_IDNA      (1 << 3)
+
+static const unsigned char *valid_star(const unsigned char *p, size_t len,
+    unsigned int flags)
+{
+        const unsigned char *star = 0;
+        size_t i;
+        int state = LABEL_START;
+        int dots = 0;
+        for (i = 0; i < len; ++i) {
+                /*
+                 * Locate first and only legal wildcard, either at the start
+                 * or end of a non-IDNA first and not final label.
+                 */
+                if (p[i] == '*') {
+                        int atstart = (state & LABEL_START);
+                        int atend = (i == len - 1 || p[i + 1] == '.');
+                        /*
+                         * At most one wildcard per pattern.
+                         * No wildcards in IDNA labels.
+                         * No wildcards after the first label.
+                         */
+                        if (star != NULL || (state & LABEL_IDNA) != 0 || dots)
+                                return NULL;
+                        /* Only full-label '*.example.com' wildcards? */
+                        if ((flags & X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)
+                            && (!atstart || !atend))
+                                return NULL;
+                        /* No 'foo*bar' wildcards */
+                        if (!atstart && !atend)
+                                return NULL;
+                        star = &p[i];
+                        state &= ~LABEL_START;
+                } else if ((state & LABEL_START) != 0) {
+                        /*
+                         * At the start of a label, skip any "xn--" and
+                         * remain in the LABEL_START state, but set the
+                         * IDNA label state
+                         */
+                        if ((state & LABEL_IDNA) == 0 && len - i >= 4
+                            && strncasecmp((char *)&p[i], "xn--", 4) == 0) {
+                                i += 3;
+                                state |= LABEL_IDNA;
+                                continue;
+                        }
+                        /* Labels must start with a letter or digit */
+                        state &= ~LABEL_START;
+                        if (('a' <= p[i] && p[i] <= 'z')
+                            || ('A' <= p[i] && p[i] <= 'Z')
+                            || ('0' <= p[i] && p[i] <= '9'))
+                                continue;
+                        return NULL;
+                } else if (('a' <= p[i] && p[i] <= 'z')
+                    || ('A' <= p[i] && p[i] <= 'Z')
+                    || ('0' <= p[i] && p[i] <= '9')) {
+                        state &= LABEL_IDNA;
+                        continue;
+                } else if (p[i] == '.') {
+                        if (state & (LABEL_HYPHEN | LABEL_START))
+                                return NULL;
+                        state = LABEL_START;
+                        ++dots;
+                } else if (p[i] == '-') {
+                        /* no domain/subdomain starts with '-' */
+                        if ((state & LABEL_START) != 0)
+                                return NULL;
+                        state |= LABEL_HYPHEN;
+                } else
+                        return NULL;
+        }
+
+        /*
+         * The final label must not end in a hyphen or ".", and
+         * there must be at least two dots after the star.
+         */
+        if ((state & (LABEL_START | LABEL_HYPHEN)) != 0 || dots < 2)
+                return NULL;
+        return star;
+}
+
+/* Compare using wildcards. */
+static int equal_wildcard(const unsigned char *pattern, size_t pattern_len,
+    const unsigned char *subject, size_t subject_len, unsigned int flags)
+{
+        const unsigned char *star = NULL;
+
+        /*
+         * Subject names starting with '.' can only match a wildcard pattern
+         * via a subject sub-domain pattern suffix match.
+         */
+        if (!(subject_len > 1 && subject[0] == '.'))
+                star = valid_star(pattern, pattern_len, flags);
+        if (star == NULL)
+                return equal_nocase(pattern, pattern_len,
+                    subject, subject_len, flags);
+        return wildcard_match(pattern, star - pattern,
+            star + 1, (pattern + pattern_len) - star - 1,
+            subject, subject_len, flags);
+}
+
+/*
+ * Compare an ASN1_STRING to a supplied string. If they match return 1. If
+ * cmp_type > 0 only compare if string matches the type, otherwise convert it
+ * to UTF8.
+ */
+
+static int
+do_check_string(ASN1_STRING *a, int cmp_type, equal_fn equal,
+    unsigned int flags, const char *b, size_t blen, char **peername)
+{
+        int rv = 0;
+
+        if (!a->data || !a->length)
+                return 0;
+        if (cmp_type > 0) {
+                if (cmp_type != a->type)
+                        return 0;
+                if (cmp_type == V_ASN1_IA5STRING)
+                        rv = equal(a->data, a->length, (unsigned char *)b,
+                            blen, flags);
+                else if (a->length == (int)blen && !memcmp(a->data, b, blen))
+                        rv = 1;
+                if (rv > 0 && peername &&
+                    (*peername = strndup((char *)a->data, a->length)) == NULL)
+                        rv = -1;
+        } else {
+                int astrlen;
+                unsigned char *astr;
+                astrlen = ASN1_STRING_to_UTF8(&astr, a);
+                if (astrlen < 0)
+                        return -1;
+                rv = equal(astr, astrlen, (unsigned char *)b, blen, flags);
+                if (rv > 0 && peername &&
+                    (*peername = strndup((char *)astr, astrlen)) == NULL)
+                        rv = -1;
+                free(astr);
+        }
+        return rv;
+}
+
+static int do_x509_check(X509 *x, const char *chk, size_t chklen,
+    unsigned int flags, int check_type, char **peername)
+{
+        GENERAL_NAMES *gens = NULL;
+        X509_NAME *name = NULL;
+        size_t i;
+        int j;
+        int cnid = NID_undef;
+        int alt_type;
+        int san_present = 0;
+        int rv = 0;
+        equal_fn equal;
+
+        /* See below, this flag is internal-only */
+        flags &= ~_X509_CHECK_FLAG_DOT_SUBDOMAINS;
+        if (check_type == GEN_EMAIL) {
+                cnid = NID_pkcs9_emailAddress;
+                alt_type = V_ASN1_IA5STRING;
+                equal = equal_email;
+        } else if (check_type == GEN_DNS) {
+                cnid = NID_commonName;
+                /* Implicit client-side DNS sub-domain pattern */
+                if (chklen > 1 && chk[0] == '.')
+                        flags |= _X509_CHECK_FLAG_DOT_SUBDOMAINS;
+                alt_type = V_ASN1_IA5STRING;
+                if (flags & X509_CHECK_FLAG_NO_WILDCARDS)
+                        equal = equal_nocase;
+                else
+                        equal = equal_wildcard;
+        } else {
+                alt_type = V_ASN1_OCTET_STRING;
+                equal = equal_case;
+        }
+
+        gens = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
+        if (gens != NULL) {
+                for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
+                        GENERAL_NAME *gen;
+                        ASN1_STRING *cstr;
+                        gen = sk_GENERAL_NAME_value(gens, i);
+                        if (gen->type != check_type)
+                                continue;
+                        san_present = 1;
+                        if (check_type == GEN_EMAIL)
+                                cstr = gen->d.rfc822Name;
+                        else if (check_type == GEN_DNS)
+                                cstr = gen->d.dNSName;
+                        else
+                                cstr = gen->d.iPAddress;
+                        /* Positive on success, negative on error! */
+                        if ((rv = do_check_string(cstr, alt_type, equal, flags,
+                            chk, chklen, peername)) != 0)
+                                break;
+                }
+                GENERAL_NAMES_free(gens);
+                if (rv != 0)
+                        return rv;
+                if (cnid == NID_undef ||
+                    (san_present &&
+                    !(flags & X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT)))
+                        return 0;
+        }
+
+        /* We're done if CN-ID is not pertinent */
+        if (cnid == NID_undef)
+                return 0;
+
+        j = -1;
+        name = X509_get_subject_name(x);
+        while ((j = X509_NAME_get_index_by_NID(name, cnid, j)) >= 0) {
+                X509_NAME_ENTRY *ne;
+                ASN1_STRING *str;
+                if ((ne = X509_NAME_get_entry(name, j)) == NULL)
+                        return -1;
+                if ((str = X509_NAME_ENTRY_get_data(ne)) == NULL)
+                        return -1;
+                /* Positive on success, negative on error! */
+                if ((rv = do_check_string(str, -1, equal, flags,
+                         chk, chklen, peername)) != 0)
+                        return rv;
+        }
+        return 0;
+}
+
+int X509_check_host(X509 *x, const char *chk, size_t chklen,
+    unsigned int flags, char **peername)
+{
+        if (chk == NULL)
+                return -2;
+        if (memchr(chk, '\0', chklen))
+                return -2;
+        return do_x509_check(x, chk, chklen, flags, GEN_DNS, peername);
+}
+
+int X509_check_email(X509 *x, const char *chk, size_t chklen,
+    unsigned int flags)
+{
+        if (chk == NULL)
+                return -2;
+        if (memchr(chk, '\0', chklen))
+                return -2;
+        return do_x509_check(x, chk, chklen, flags, GEN_EMAIL, NULL);
+}
+
+int X509_check_ip(X509 *x, const unsigned char *chk, size_t chklen,
+    unsigned int flags)
+{
+        if (chk == NULL)
+                return -2;
+        return do_x509_check(x, (char *)chk, chklen, flags, GEN_IPADD, NULL);
+}
+
+int X509_check_ip_asc(X509 *x, const char *ipasc, unsigned int flags)
+{
+        unsigned char ipout[16];
+        size_t iplen;
+
+        if (ipasc == NULL)
+                return -2;
+        iplen = (size_t)a2i_ipadd(ipout, ipasc);
+        if (iplen == 0)
+                return -2;
+        return do_x509_check(x, (char *)ipout, iplen, flags, GEN_IPADD, NULL);
+}
+
 /* Convert IP addresses both IPv4 and IPv6 into an
  * OCTET STRING compatible with RFC3280.
  */
diff --git a/src/lib/libcrypto/x509v3/x509v3.h b/src/lib/libcrypto/x509v3/x509v3.h
index b45626a885..c13342f349 100644
--- a/src/lib/libcrypto/x509v3/x509v3.h
+++ b/src/lib/libcrypto/x509v3/x509v3.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: x509v3.h,v 1.16 2015/02/10 13:28:17 jsing Exp $ */
+/* $OpenBSD: x509v3.h,v 1.17 2016/09/03 11:56:33 beck Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 1999.
  */
@@ -701,6 +701,33 @@ STACK_OF(OPENSSL_STRING) *X509_REQ_get1_email(X509_REQ *x);
 void X509_email_free(STACK_OF(OPENSSL_STRING) *sk);
 STACK_OF(OPENSSL_STRING) *X509_get1_ocsp(X509 *x);
 
+/* Flags for X509_check_* functions */
+/* Always check subject name for host match even if subject alt names present */
+#define X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT    0x1
+/* Disable wildcard matching for dnsName fields and common name. */
+#define X509_CHECK_FLAG_NO_WILDCARDS    0x2
+/* Wildcards must not match a partial label. */
+#define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0x4
+/* Allow (non-partial) wildcards to match multiple labels. */
+#define X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS 0x8
+/* Constraint verifier subdomain patterns to match a single labels. */
+#define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0x10
+
+/*
+ * Match reference identifiers starting with "." to any sub-domain.
+ * This is a non-public flag, turned on implicitly when the subject
+ * reference identity is a DNS name.
+ */
+#define _X509_CHECK_FLAG_DOT_SUBDOMAINS 0x8000
+
+int X509_check_host(X509 *x, const char *chk, size_t chklen,
+    unsigned int flags, char **peername);
+int X509_check_email(X509 *x, const char *chk, size_t chklen,
+    unsigned int flags);
+int X509_check_ip(X509 *x, const unsigned char *chk, size_t chklen,
+    unsigned int flags);
+int X509_check_ip_asc(X509 *x, const char *ipasc, unsigned int flags);
+
 ASN1_OCTET_STRING *a2i_IPADDRESS(const char *ipasc);
 ASN1_OCTET_STRING *a2i_IPADDRESS_NC(const char *ipasc);
 int a2i_ipadd(unsigned char *ipout, const char *ipasc);