# HG changeset patch
# User Christian Brabandt <cb@256bit.org>
# Date 1698352203 -7200
# Node ID 06b59278bfcfb635004809db9e7a489ed6324638
# Parent  e14a179650d8a02c914c86525880a50adc1aff9f
patch 9.0.2070: [security] disallow setting env in restricted mode

Commit: https://github.com/vim/vim/commit/6b89dd6a7257a1e2e9c7ea070b407bc4674a5118
Author: Christian Brabandt <cb@256bit.org>
Date:   Thu Oct 26 22:14:17 2023 +0200

    patch 9.0.2070: [security] disallow setting env in restricted mode

    Problem:  [security] disallow setting env in restricted mode
    Solution: Setting environment variables in restricted mode could
              potentially be used to execute shell commands. Disallow this.

    restricted mode: disable allow setting of environment variables

    Setting environment variables in restricted mode, may have some unwanted
    consequences. So, for example by setting $GCONV_PATH in restricted mode
    and then calling the iconv() function, one may be able to execute some
    unwanted payload, because the `iconv_open()` function internally uses
    the `$GCONV_PATH` variable to find its conversion data.

    So let's disable setting environment variables, even so this is no
    complete protection, since we are not clearing the existing environment.
    I tried a few ways but wasn't successful :(

    One could also argue to disable the iconv() function completely in
    restricted mode, but who knows what other API functions can be
    influenced by setting some other unrelated environment variables.
    So let's leave it as it is currently.

    closes: #13394
    See: https://huntr.com/bounties/b0a2eda1-459c-4e36-98e6-0cc7d7faccfe/

    Signed-off-by: Christian Brabandt <cb@256bit.org>

diff --git a/runtime/doc/starting.txt b/runtime/doc/starting.txt
--- a/runtime/doc/starting.txt
+++ b/runtime/doc/starting.txt
@@ -1,4 +1,4 @@
-*starting.txt*  For Vim version 9.0.  Last change: 2023 Oct 17
+*starting.txt*  For Vim version 9.0.  Last change: 2023 Oct 20
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -249,10 +249,10 @@ a slash.  Thus "-R" means recovery and "
 					*-Z* *restricted-mode* *E145* *E981*
 -Z		Restricted mode.  All commands that make use of an external
 		shell are disabled.  This includes suspending with CTRL-Z,
-		":sh", filtering, the system() function, backtick expansion
+		":sh", filtering, the |system()| function, backtick expansion
 		and libcall().
-		Also disallowed are delete(), rename(), mkdir(), job_start(),
-		etc.
+		Also disallowed are |delete()|, |rename()|, |mkdir()|,
+		|job_start()|, |setenv()| etc.
 		Interfaces, such as Python, Ruby and Lua, are also disabled,
 		since they could be used to execute shell commands.  Perl uses
 		the Safe module.
diff --git a/src/evalfunc.c b/src/evalfunc.c
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -9723,6 +9723,12 @@ f_setenv(typval_T *argvars, typval_T *re
     if (in_vim9script() && check_for_string_arg(argvars, 0) == FAIL)
 	return;
 
+    // seting an environment variable may be dangerous, e.g. you could
+    // setenv GCONV_PATH=/tmp and then have iconv() unexpectedly call
+    // a shell command using some shared library:
+    if (check_restricted() || check_secure())
+	return;
+
     name = tv_get_string_buf(&argvars[0], namebuf);
     if (argvars[1].v_type == VAR_SPECIAL
 				      && argvars[1].vval.v_number == VVAL_NULL)
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2070,
+/**/
     2069,
 /**/
     2068,