Don't allow null chars in various strings

Various places that now reject null chars inside strings
- Primitive file operations reject it in filenames.
- Primitive environment variable operations reject it in
  names and values.
- os:cmd() reject it in its input.

Also '=' characters are rejected by primitive environment
variable operations in environment variable names.

Documentation has been updated to document null characters
in these types of data as invalid. Currently these operations
accept null chars at the end of strings, but that will change
in the future.

1 files changed, 53 insertions, 22 deletions

diff --git a/erts/emulator/beam/erl_bif_os.c b/erts/emulator/beam/erl_bif_os.c
index 5cd172c26f..910325a2f4 100644
--- a/erts/emulator/beam/erl_bif_os.c
+++ b/erts/emulator/beam/erl_bif_os.c
@@ -37,6 +37,8 @@
 #include "dist.h"
 #include "erl_version.h"
 
+static int check_env_name(char *name);
+
 /*
  * Return the pid for the Erlang process in the host OS.
  */
@@ -101,8 +103,10 @@ BIF_RETTYPE os_getenv_1(BIF_ALIST_1)
     key_str = erts_convert_filename_to_native(BIF_ARG_1,buf,STATIC_BUF_SIZE,
 					      ERTS_ALC_T_TMP,1,0,&len);
 
-    if (!key_str) {
-	BIF_ERROR(p, BADARG);
+    if (!check_env_name(key_str)) {
+        if (key_str && key_str != &buf[0])
+            erts_free(ERTS_ALC_T_TMP, key_str);
+        BIF_ERROR(p, BADARG);
     }
 
     if (key_str != &buf[0])
@@ -143,25 +147,20 @@ BIF_RETTYPE os_putenv_2(BIF_ALIST_2)
 {
     char def_buf_key[STATIC_BUF_SIZE];
     char def_buf_value[STATIC_BUF_SIZE];
-    char *key_buf, *value_buf;
+    char *key_buf = NULL, *value_buf = NULL;
 
     key_buf = erts_convert_filename_to_native(BIF_ARG_1,def_buf_key,
 					      STATIC_BUF_SIZE,
 					      ERTS_ALC_T_TMP,0,0,NULL);
-    if (!key_buf) {
-	BIF_ERROR(BIF_P, BADARG);
-    }
+    if (!check_env_name(key_buf))
+        goto badarg;
+
     value_buf = erts_convert_filename_to_native(BIF_ARG_2,def_buf_value,
 						STATIC_BUF_SIZE,
 						ERTS_ALC_T_TMP,1,0,
 						NULL);
-    if (!value_buf) {
-	if (key_buf != def_buf_key) {
-	    erts_free(ERTS_ALC_T_TMP, key_buf);
-	}
-	BIF_ERROR(BIF_P, BADARG);
-    }
-	    
+    if (!value_buf)
+        goto badarg;
 
     if (erts_sys_putenv(key_buf, value_buf)) {
 	if (key_buf != def_buf_key) {
@@ -179,6 +178,13 @@ BIF_RETTYPE os_putenv_2(BIF_ALIST_2)
 	erts_free(ERTS_ALC_T_TMP, value_buf);
     }
     BIF_RET(am_true);
+
+badarg:
+    if (key_buf && key_buf != def_buf_key)
+	erts_free(ERTS_ALC_T_TMP, key_buf);
+    if (value_buf && value_buf != def_buf_value)
+	erts_free(ERTS_ALC_T_TMP, value_buf);
+    BIF_ERROR(BIF_P, BADARG);
 }
 
 BIF_RETTYPE os_unsetenv_1(BIF_ALIST_1)
@@ -188,20 +194,21 @@ BIF_RETTYPE os_unsetenv_1(BIF_ALIST_1)
 
     key_buf = erts_convert_filename_to_native(BIF_ARG_1,buf,STATIC_BUF_SIZE,
 					      ERTS_ALC_T_TMP,0,0,NULL);
-    if (!key_buf) {
-	BIF_ERROR(BIF_P, BADARG);
-    }
+    if (!check_env_name(key_buf))
+        goto badarg;
+
+    if (erts_sys_unsetenv(key_buf))
+        goto badarg;
 
-    if (erts_sys_unsetenv(key_buf)) {
-	if (key_buf != buf) {
-	    erts_free(ERTS_ALC_T_TMP, key_buf);
-	}
-	BIF_ERROR(BIF_P, BADARG);
-    }
     if (key_buf != buf) {
 	erts_free(ERTS_ALC_T_TMP, key_buf);
     }
     BIF_RET(am_true);
+
+badarg:
+    if (key_buf && key_buf != buf)
+        erts_free(ERTS_ALC_T_TMP, key_buf);
+    BIF_ERROR(BIF_P, BADARG);    
 }
 
 BIF_RETTYPE os_set_signal_2(BIF_ALIST_2) {
@@ -217,3 +224,27 @@ BIF_RETTYPE os_set_signal_2(BIF_ALIST_2) {
 error:
     BIF_ERROR(BIF_P, BADARG);
 }
+
+static int
+check_env_name(char *raw_name)
+{
+    byte *c = (byte *) raw_name;
+    int encoding;
+
+    if (!c)
+        return 0;
+    
+    encoding = erts_get_native_filename_encoding();
+
+    if (erts_raw_env_char_is_7bit_ascii_char('\0', c, encoding))
+        return 0; /* Do not allow empty name... */
+
+    /* Verify no '=' characters in variable name... */
+    do {
+        if (erts_raw_env_char_is_7bit_ascii_char('=', c, encoding))
+            return 0;
+        c = erts_raw_env_next_char(c, encoding);
+    } while (!erts_raw_env_char_is_7bit_ascii_char('\0', c, encoding));
+
+    return 1; /* Seems ok... */
+}