X.509 matching split out; disallow TLD wildcards.

5 files changed, 92 insertions, 37 deletions

diff --git a/Makefile.am b/Makefile.am
index 0e597d05..6a12786b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -38,7 +38,7 @@ libfm_a_SOURCES=	xmalloc.c base64.c rfc822.c report.c rfc2047e.c \
 			smbencrypt.h smbdes.c smbencrypt.c smbmd4.c smbutil.c \
 			libesmtp/gethostbyname.h libesmtp/gethostbyname.c \
 			smbtypes.h fm_getaddrinfo.c tls.c rfc822valid.c \
-			xmalloc.h sdump.h sdump.c
+			xmalloc.h sdump.h sdump.c x509_name_match.c
 libfm_a_LIBADD=		$(EXTRAOBJ)
 libfm_a_DEPENDENCIES=	$(EXTRAOBJ)
 LDADD	=		libfm.a @LIBINTL@ $(LIBOBJS)
diff --git a/NEWS b/NEWS
index a63a3d9c..06e3f855 100644
--- a/NEWS
+++ b/NEWS
@@ -63,6 +63,7 @@ fetchmail-6.3.18 (not yet released):
   The test is overly picky and triggers if the pattern (after skipping the
   initial wildcard "*") or domain consist solely of digits and dots and matches
   more than needed.
+* Fetchmail now disallows wildcarding top-level domains.
 
 # BUG FIXES
 * Fetchmail would warn about insecure SSL/TLS connections even if a matching
diff --git a/fetchmail.h b/fetchmail.h
index 0315a9da..9502d1e3 100644
--- a/fetchmail.h
+++ b/fetchmail.h
@@ -772,6 +772,9 @@ int must_tls(struct query *ctl);
 /* prototype from rfc822valid.c */
 int rfc822_valid_msgid(const unsigned char *);
 
+/* prototype from x509_name_match.c */
+int name_match(const char *p1, const char *p2);
+
 /* macro to determine if we want to spam progress to stdout */
 #define want_progress() \
 	((outlevel >= O_VERBOSE || (outlevel > O_SILENT && run.showdots)) \
diff --git a/socket.c b/socket.c
index d3cf90d7..2a3e1ba1 100644
--- a/socket.c
+++ b/socket.c
@@ -593,42 +593,6 @@ SSL *SSLGetContext( int sock )
 	return _ssl_context[sock];
 }
 
-/** A picky certificate name check:
- * check if the pattern or string in s1 (from a certificate) matches the
- * hostname (in s2), returns true if matched.
- *
- * The only place where a wildcard is allowed is in the leftmost
- * position of p1. */
-static int name_match(const char *p1, const char *p2) {
-    const char *const dom = "0123456789.";
-    int wildcard_ok = 1;
-
-    /* blank patterns never match */
-    if (p1[0] == '\0')
-	return 0;
-
-    /* disallow wildcards in certificates for domain literals
-     * (10.9.8.7-like) */
-    if (strspn(p1+(*p1 == '*' ? 1 : 0), dom) == strlen(p1))
-	wildcard_ok = 0;
-
-    /* disallow wildcards for domain literals */
-    if (strspn(p2, dom) == strlen(p2))
-	wildcard_ok = 0;
-
-    if (wildcard_ok && p1[0] == '*' && p1[1] == '.') {
-	size_t l1, l2;
-
-	++p1;
-	l1 = strlen(p1);
-	l2 = strlen(p2);
-	if (l2 > l1)
-	    p2 += l2 - l1;
-    }
-
-    return (0 == strcasecmp(p1, p2));
-}
-
 /* ok_return (preverify_ok) is 1 if this stage of certificate verification
    passed, or 0 if it failed. This callback lets us display informative
    errors, and perform additional validation (e.g. CN matches) */
diff --git a/x509_name_match.c b/x509_name_match.c
new file mode 100644
index 00000000..ddfee3eb
--- /dev/null
+++ b/x509_name_match.c
@@ -0,0 +1,87 @@
+#include "fetchmail.h"
+
+#include <string.h>
+#include <strings.h>
+
+/** A picky certificate name check:
+ * check if the pattern or string in s1 (from a certificate) matches the
+ * hostname (in s2), returns true if matched.
+ *
+ * The only place where a wildcard is allowed is in the leftmost
+ * position of p1. */
+int name_match(const char *p1, const char *p2) {
+    const char *const dom = "0123456789.";
+    int wildcard_ok = 1;
+
+    /* blank patterns never match */
+    if (p1[0] == '\0')
+	return 0;
+
+    /* disallow wildcards in certificates for domain literals
+     * (10.9.8.7-like) */
+    if (strspn(p1+(*p1 == '*' ? 1 : 0), dom) == strlen(p1))
+	wildcard_ok = 0;
+
+    /* disallow wildcards for domain literals */
+    if (strspn(p2, dom) == strlen(p2))
+	wildcard_ok = 0;
+
+    if (wildcard_ok && p1[0] == '*' && p1[1] == '.') {
+	size_t l1, l2;
+	int number_dots = 0;
+	const char *tmp;
+
+	++p1;
+	/* make sure CAs don't wildcard top-level domains by requiring there
+	 * are at least two dots in wildcarded X.509 CN/SANs */
+
+	for(tmp = p1; *tmp; tmp += strcspn(tmp, ".")) {
+	    if (*tmp == '.') {
+		++number_dots;
+		++tmp;
+	    }
+	}
+
+	if (number_dots >= 2) {
+	    l1 = strlen(p1);
+	    l2 = strlen(p2);
+	    if (l2 > l1)
+		p2 += l2 - l1;
+	}
+    }
+
+    return (0 == strcasecmp(p1, p2));
+}
+
+#ifdef TEST
+#include <stdlib.h>
+#include <stdio.h>
+
+static int verbose;
+
+/* print test and return true on failure */
+static int test(const char *p1, const char *p2, int expect) {
+    int match = name_match(p1, p2);
+    if (verbose)
+	printf("name_match(\"%s\", \"%s\") == %d (%d expected)\n", p1, p2, match, expect);
+    return expect != match;
+}
+
+int main(int argc, const char **argv) {
+    int rc = 0;
+
+    if (argc > 1 && 0 == strcmp(argv[1], "-v"))
+	verbose = 1;
+
+    rc |= test("example.org", "example.org", 1);
+    rc |= test("*example.org", "foo.example.org", 0);
+    rc |= test("*.example.org", "foo.example.org", 1);
+    rc |= test("*.168.23.23", "192.168.23.23", 0);
+    rc |= test("*.com", "example.com", 0);
+    if (verbose) {
+	printf("x509_name_match: ");
+	puts(rc ? "FAIL" : "PASS");
+    }
+    return rc;
+}
+#endif