Linux sandbox: save full list of SUID unsafe environment variables.

sandbox/linux/suid/sandbox.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // http://code.google.com/p/chromium/wiki/LinuxSUIDSandbox
 
 #include <asm/unistd.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <sched.h>
 #include <signal.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/prctl.h>
 #include <sys/resource.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <unistd.h>
 
+#include "sandbox/linux/suid/suid_unsafe_environment_variables.h"
+
 #if !defined(CLONE_NEWPID)
 #define CLONE_NEWPID 0x20000000
 #endif
 
 #if !defined(LINUX_SANDBOX_CHROME_PATH) && \
     !defined(CHROME_DEVEL_SANDBOX)
 #error LINUX_SANDBOX_CHROME_PATH must be defined to be the location of the \
        Chrome binary, or CHROME_DEVEL_SANDBOX must be defined
 #endif
 
@@ skipping 187 matching lines @@
 
   if (setresuid(ruid, ruid, ruid)) {
     perror("setresuid");
     return false;
   }
 
   return true;
 }
 
 static bool SetupChildEnvironment() {
-  // ld.so will have cleared LD_LIBRARY_PATH because we are SUID. However, the
-  // child process might need this so zygote_host_linux.cc saved a copy in
-  // SANDBOX_LD_LIBRARY_PATH. This is safe because we have dropped root by this
+  // ld.so may have cleared several environment variable because we are SUID.

[Evan Martin, 2009/07/17 21:10:57]

variable*s*

[agl, 2009/07/17 21:35:09]

Done.

+  // However, the child process might need them so zygote_host_linux.cc saves a
+  // copy in SANDBOX_$x. This is safe because we have dropped root by this
   // point, so we can only exec a binary with the permissions of the user who
   // ran us in the first place.
-  const char* sandbox_ld_library_path = getenv("SANDBOX_LD_LIBRARY_PATH");
-  if (sandbox_ld_library_path) {
-    setenv("LD_LIBRARY_PATH", sandbox_ld_library_path, 1 /* overwrite */);
-    unsetenv("SANDBOX_LD_LIBRARY_PATH");
+
+  for (unsigned i = 0; kSUIDUnsafeEnvironmentVariables[i]; ++i) {
+    const char* const envvar = kSUIDUnsafeEnvironmentVariables[i];
+    char* const saved_envvar = SandboxSavedEnvironmentVariable(envvar);
+    if (!saved_envvar)
+      return false;
+
+    const char* const value = getenv(saved_envvar);
+    if (value) {
+      setenv(envvar, value, 1 /* overwrite */);
+      unsetenv(saved_envvar);
+    }
+
+    free(saved_envvar);
   }
 
   return true;
 }
 
 int main(int argc, char **argv) {
   if (argc == 1) {
     fprintf(stderr, "Usage: %s <renderer process> <args...>\n", argv[0]);
     return 1;
   }
@@ skipping 56 matching lines @@
   if (!DropRoot())
     return 1;
   if (!SetupChildEnvironment())
     return 1;
 
   execv(argv[1], &argv[1]);
   FatalError("execv failed");
 
   return 1;
 }