api: improve api string safety

- Remove vl_api_from_api_string
  to prevent use of not nul-terminated strings.
- Rename vl_api_from_api_to_vec -> vl_api_from_api_to_new_vec
  to imply a new vector is created. NOT nul terminated.
- Add vl_api_from_api_to_new_c_string. Returns
  nul terminated string in a new vector.
- Add vl_api_c_string_to_api_string. Convert nul terminated
  string to vl_api_string_t
- Add vl_api_vec_to_api_string. Convert NON nul terminated
  vector to vl_api_string_t

Type: fix

Signed-off-by: Jakub Grajciar <jgrajcia@cisco.com>
Change-Id: Iadd59b612c0d960a34ad0dd07a9d17f56435c6ea
Signed-off-by: Jakub Grajciar <jgrajcia@cisco.com>

2 files changed, 34 insertions, 13 deletions

diff --git a/src/vlibapi/api_shared.c b/src/vlibapi/api_shared.c
index aba853dc997..28e9f481650 100644
--- a/src/vlibapi/api_shared.c
+++ b/src/vlibapi/api_shared.c
@@ -1091,15 +1091,19 @@ vl_msg_pop_heap (void *oldheap)
   vl_msg_pop_heap_w_region (am->vlib_rp, oldheap);
 }
 
+/* Must be nul terminated */
 int
-vl_api_to_api_string (u32 len, const char *buf, vl_api_string_t * str)
+vl_api_c_string_to_api_string (const char *buf, vl_api_string_t * str)
 {
-  if (len)
+  /* copy without nul terminator */
+  u32 len = strlen (buf);
+  if (len > 0)
     clib_memcpy_fast (str->buf, buf, len);
   str->length = htonl (len);
   return len + sizeof (u32);
 }
 
+/* Must NOT be nul terminated */
 int
 vl_api_vec_to_api_string (const u8 * vec, vl_api_string_t * str)
 {
@@ -1109,13 +1113,6 @@ vl_api_vec_to_api_string (const u8 * vec, vl_api_string_t * str)
   return len + sizeof (u32);
 }
 
-/* Return a pointer to the API string (not nul terminated */
-u8 *
-vl_api_from_api_string (vl_api_string_t * astr)
-{
-  return astr->buf;
-}
-
 u32
 vl_api_string_len (vl_api_string_t * astr)
 {
@@ -1132,15 +1129,32 @@ vl_api_format_string (u8 * s, va_list * args)
 
 /*
  * Returns a new vector. Remember to free it after use.
+ * NOT nul terminated.
  */
 u8 *
-vl_api_from_api_to_vec (vl_api_string_t * astr)
+vl_api_from_api_to_new_vec (vl_api_string_t * astr)
 {
   u8 *v = 0;
   vec_add (v, astr->buf, clib_net_to_host_u32 (astr->length));
   return v;
 }
 
+/*
+ * Returns a new vector. Remember to free it after use.
+ * Nul terminated.
+ */
+char *
+vl_api_from_api_to_new_c_string (vl_api_string_t * astr)
+{
+  char *v = 0;
+  if (clib_net_to_host_u32 (astr->length) > 0)
+    {
+      vec_add (v, astr->buf, clib_net_to_host_u32 (astr->length));
+      vec_add1 (v, 0);
+    }
+  return v;
+}
+
 void
 vl_api_set_elog_main (elog_main_t * m)
 {
diff --git a/src/vlibapi/api_types.h b/src/vlibapi/api_types.h
index 8cd47bb770f..21fcde53b0e 100644
--- a/src/vlibapi/api_types.h
+++ b/src/vlibapi/api_types.h
@@ -38,11 +38,18 @@ typedef struct
   u8 buf[0];
 } __attribute__ ((packed)) vl_api_string_t;
 
-extern int vl_api_to_api_string (u32 len, const char *buf, vl_api_string_t * str);
+/* Nul terminated string to vl_api_string_t */
+extern int vl_api_c_string_to_api_string (const char *buf, vl_api_string_t * str);
+/* NON nul terminated vector to vl_api_string_t */
 extern int vl_api_vec_to_api_string (const u8 *vec, vl_api_string_t * str);
-extern u8 * vl_api_from_api_string (vl_api_string_t * astr);
+
 extern u32 vl_api_string_len (vl_api_string_t * astr);
-extern u8 * vl_api_from_api_to_vec (vl_api_string_t *astr);
+
+/* Returns new vector. NON nul terminated */
+extern u8 * vl_api_from_api_to_new_vec (vl_api_string_t *astr);
+/* Returns new vector. Nul terminated */
+extern char * vl_api_from_api_to_new_c_string (vl_api_string_t *astr);
+
 extern u8 *vl_api_format_string (u8 *s, va_list *args);
 
 #ifdef __cplusplus