Run NaClEnvCleanser in standalone sel_ldr (in addition to sel_main_chrome). Add a couple of ld.so...

src/trusted/service_runtime/env_cleanser.c

 /*
  * Copyright 2009 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can
  * be found in the LICENSE file.
  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "native_client/src/include/portability.h"
 #include "native_client/src/include/nacl_macros.h"
 
 #include "native_client/src/trusted/service_runtime/env_cleanser.h"
 #include "native_client/src/trusted/service_runtime/env_cleanser_test.h"
 
-void NaClEnvCleanserCtor(struct NaClEnvCleanser *self) {
+/*
+ * Everything that starts with this prefix is allowed (but the prefix is
+ * stripped away).
+*/
+#define NACL_ENV_PREFIX "NACLENV_"
+#define NACL_ENV_PREFIX_LENGTH 8
+
+void NaClEnvCleanserCtor(struct NaClEnvCleanser *self, int with_whitelist) {
+  self->with_whitelist = with_whitelist;
   self->cleansed_environ = (char const **) NULL;
 }
 
 /*
  * Environment variables names are from IEEE Std 1003.1-2001, with
  * additional ones from locale(7) from glibc / linux.  The entries
  * must be sorted, in ASCII order, for the bsearch to run correctly.
  */
 /* static -- not static for testing */
 char const *const kNaClEnvWhitelist[] = {
@@ skipping 30 matching lines @@
          && '\0' != cright) {
     ++left;
     ++right;
   }
   if ('=' == cleft && '\0' == cright) {
     return 0;
   }
   return (0xff & cleft) - (0xff & cright);
 }
 
+int NaClEnvIsPassThroughVar(char const *env_entry) {
+  return strlen(env_entry) > NACL_ENV_PREFIX_LENGTH &&
+      0 == strncmp(env_entry, NACL_ENV_PREFIX,
+          NACL_ENV_PREFIX_LENGTH);
+}
+
 int NaClEnvInWhitelist(char const *env_entry) {
   return NULL != bsearch((void const *) &env_entry,
                          (void const *) kNaClEnvWhitelist,
                          NACL_ARRAY_SIZE(kNaClEnvWhitelist) - 1,  /* NULL */
                          sizeof kNaClEnvWhitelist[0],
                          EnvCmp);
 }
 
 /* PRE: sizeof(char *) is a power of 2 */
 
 /*
  * Initializes the object with a filtered environment.
  *
  * May return false on errors, e.g., out-of-memory.
  */
-int NaClEnvCleanserInit(struct NaClEnvCleanser *self, char const *const *envp) {
+int NaClEnvCleanserInit(struct NaClEnvCleanser *self, char const *const *envp,
+    char const * const *extra_env) {
   char const *const *p;
   size_t num_env = 0;
   size_t ptr_bytes = 0;
   const size_t kMaxSize = ~(size_t) 0;
   const size_t ptr_size_mult_overflow_mask = ~(kMaxSize / sizeof *envp);
   char const **ptr_tbl;
   size_t env;
 
   /*
    * let n be a size_t.  if n & ptr_size_mult_overflow_mask is set,
    * then n*sizeof(void *) will have an arithmetic overflow.
    */
 
   if (NULL == envp || NULL == *envp) {
     self->cleansed_environ = NULL;
     return 1;
   }
   for (p = envp; NULL != *p; ++p) {
-    if (!NaClEnvInWhitelist(*p)) {
+    if (!(self->with_whitelist && NaClEnvInWhitelist(*p)) && !NaClEnvIsPassThroughVar(*p)) {
       continue;
     }
     if (num_env == kMaxSize) {
       /* would overflow */
       return 0;
     }
     ++num_env;
   }
 
+  if (extra_env) {
+    for (p = extra_env; NULL != *p; ++p) {
+      if (num_env == kMaxSize) {
+        /* would overflow */
+        return 0;
+      }
+      ++num_env;
+    }
+  }
+
   /* pointer table -- NULL pointer terminated */
   if (0 != ((1 + num_env) & ptr_size_mult_overflow_mask)) {
     return 0;
   }
   ptr_bytes = (1 + num_env) * sizeof(*envp);
 
   ptr_tbl = (char const **) malloc(ptr_bytes);
   if (NULL == ptr_tbl) {
     return 0;
   }
 
   /* this assumes no other thread is tweaking envp */
   for (env = 0, p = envp; NULL != *p; ++p) {
-    if (!NaClEnvInWhitelist(*p)) {
+    if (NaClEnvIsPassThroughVar(*p)) {
+      ptr_tbl[env] = *p + NACL_ENV_PREFIX_LENGTH;
+    } else if (self->with_whitelist && NaClEnvInWhitelist(*p)) {
+      ptr_tbl[env] = *p;
+    } else {
       continue;
     }
-    ptr_tbl[env] = *p;
     ++env;
   }
+  if (extra_env) {
+    for (p = extra_env; NULL != *p; ++p) {
+      ptr_tbl[env] = *p;
+      ++env;
+    }
+  }
   if (num_env != env) {
     free((void *) ptr_tbl);
     return 0;
   }
   ptr_tbl[env] = NULL;
   self->cleansed_environ = ptr_tbl;
 
   return 1;
 }
 
 char const *const *NaClEnvCleanserEnvironment(struct NaClEnvCleanser *self) {
   return (char const *const *) self->cleansed_environ;
 }
 
 void NaClEnvCleanserDtor(struct NaClEnvCleanser *self) {
   free((void *) self->cleansed_environ);
   self->cleansed_environ = NULL;
 }