Switch IDNA implementation to libidn2 [BZ #19728] [BZ #19729] [BZ #22247]

This provides an implementation of the IDNA2008 standard and fixes
CVE-2016-6261, CVE-2016-6263, CVE-2017-14062.

1 files changed, 182 insertions, 0 deletions

diff --git a/inet/idna.c b/inet/idna.c
new file mode 100644
index 0000000000..c561bf2e9e
--- /dev/null
+++ b/inet/idna.c
@@ -0,0 +1,182 @@
+/* IDNA functions, forwarding to implementations in libidn2.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <allocate_once.h>
+#include <dlfcn.h>
+#include <inet/net-internal.h>
+#include <netdb.h>
+#include <stdbool.h>
+
+/* Use the soname and version to locate libidn2, to ensure a
+   compatible ABI.  */
+#define LIBIDN2_SONAME "libidn2.so.0"
+#define LIBIDN2_VERSION "IDN2_0.0.0"
+
+/* Return codes from libidn2.  */
+enum
+  {
+    IDN2_OK = 0,
+    IDN2_MALLOC = -100,
+  };
+
+/* Functions from libidn2.  */
+struct functions
+{
+  void *handle;
+  int (*lookup_ul) (const char *src, char **result, int flags);
+  int (*to_unicode_lzlz) (const char *name, char **result, int flags);
+};
+
+static void *
+functions_allocate (void *closure)
+{
+  struct functions *result = malloc (sizeof (*result));
+  if (result == NULL)
+    return NULL;
+
+  void *handle = __libc_dlopen (LIBIDN2_SONAME);
+  if (handle == NULL)
+    /* Do not cache open failures.  The library may appear
+       later.  */
+    {
+      free (result);
+      return NULL;
+    }
+
+  void *ptr_lookup_ul
+    = __libc_dlvsym (handle, "idn2_lookup_ul", LIBIDN2_VERSION);
+  void *ptr_to_unicode_lzlz
+    = __libc_dlvsym (handle, "idn2_to_unicode_lzlz", LIBIDN2_VERSION);
+  if (ptr_lookup_ul == NULL || ptr_to_unicode_lzlz == NULL)
+    {
+      __libc_dlclose (handle);
+      free (result);
+      return NULL;
+    }
+
+  result->handle = handle;
+  result->lookup_ul = ptr_lookup_ul;
+  result->to_unicode_lzlz = ptr_to_unicode_lzlz;
+#ifdef PTR_MANGLE
+  PTR_MANGLE (result->lookup_ul);
+  PTR_MANGLE (result->to_unicode_lzlz);
+#endif
+
+  return result;
+}
+
+static void
+functions_deallocate (void *closure, void *ptr)
+{
+  struct functions *functions = ptr;
+  __libc_dlclose (functions->handle);
+  free (functions);
+}
+
+/* Ensure that *functions is initialized and return the value of the
+   pointer.  If the library cannot be loaded, return NULL.  */
+static inline struct functions *
+get_functions (void)
+{
+  static void *functions;
+  return allocate_once (&functions, functions_allocate, functions_deallocate,
+                        NULL);
+}
+
+/* strdup with an EAI_* error code.  */
+static int
+gai_strdup (const char *name, char **result)
+{
+  char *ptr = __strdup (name);
+  if (ptr == NULL)
+    return EAI_MEMORY;
+  *result = ptr;
+  return 0;
+}
+
+int
+__idna_to_dns_encoding (const char *name, char **result)
+{
+  switch (__idna_name_classify (name))
+    {
+    case idna_name_ascii:
+      /* Nothing to convert.  */
+      return gai_strdup (name, result);
+    case idna_name_nonascii:
+      /* Encoding needed.  Handled below.  */
+      break;
+    case idna_name_nonascii_backslash:
+    case idna_name_encoding_error:
+      return EAI_IDN_ENCODE;
+    case idna_name_memory_error:
+      return EAI_MEMORY;
+    case idna_name_error:
+      return EAI_SYSTEM;
+    }
+
+  struct functions *functions = get_functions ();
+  if (functions == NULL)
+    /* We report this as an encoding error (assuming that libidn2 is
+       not installed), although the root cause may be a temporary
+       error condition due to resource shortage.  */
+    return EAI_IDN_ENCODE;
+  char *ptr = NULL;
+  __typeof__ (functions->lookup_ul) fptr = functions->lookup_ul;
+#ifdef PTR_DEMANGLE
+  PTR_DEMANGLE (fptr);
+#endif
+  int ret = fptr (name, &ptr, 0);
+  if (ret == 0)
+    {
+      /* Assume that idn2_free is equivalent to free.  */
+      *result = ptr;
+      return 0;
+    }
+  else if (ret == IDN2_MALLOC)
+    return EAI_MEMORY;
+  else
+    return EAI_IDN_ENCODE;
+}
+libc_hidden_def (__idna_to_dns_encoding)
+
+int
+__idna_from_dns_encoding (const char *name, char **result)
+{
+  struct functions *functions = get_functions ();
+  if (functions == NULL)
+    /* Simply use the encoded name, assuming that it is not punycode
+       (but even a punycode name would be syntactically valid).  */
+    return gai_strdup (name, result);
+  char *ptr = NULL;
+  __typeof__ (functions->to_unicode_lzlz) fptr = functions->to_unicode_lzlz;
+#ifdef PTR_DEMANGLE
+  PTR_DEMANGLE (fptr);
+#endif
+  int ret = fptr (name, &ptr, 0);
+  if (ret == 0)
+    {
+      /* Assume that idn2_free is equivalent to free.  */
+      *result = ptr;
+      return 0;
+    }
+  else if (ret == IDN2_MALLOC)
+    return EAI_MEMORY;
+  else
+    return EAI_IDN_ENCODE;
+}
+libc_hidden_def (__idna_from_dns_encoding)