akr	2014-09-04 23:56:03 +0900 (Thu, 04 Sep 2014)

  New Revision: 47386

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=47386

  Log:
    * process.c (has_privilege): New function.
      (retry_fork_async_signal_safe): Don't use vfork() for privileged
      process.
    
    * configure.in (getresuid): Check function.
      (getresgid): Ditto.

  Modified files:
    trunk/ChangeLog
    trunk/configure.in
    trunk/process.c
Index: configure.in
===================================================================
--- configure.in	(revision 47385)
+++ configure.in	(revision 47386)
@@ -1996,6 +1996,8 @@ AC_CHECK_FUNCS(getpgid) https://github.com/ruby/ruby/blob/trunk/configure.in#L1996
 AC_CHECK_FUNCS(getpgrp)
 AC_CHECK_FUNCS(getpriority)
 AC_CHECK_FUNCS(getpwnam_r)
+AC_CHECK_FUNCS(getresgid)
+AC_CHECK_FUNCS(getresuid)
 AC_CHECK_FUNCS(getrlimit)
 AC_CHECK_FUNCS(getsid)
 AC_CHECK_FUNCS(gettimeofday)		# for making ac_cv_func_gettimeofday
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 47385)
+++ ChangeLog	(revision 47386)
@@ -1,3 +1,12 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Thu Sep  4 23:39:52 2014  Tanaka Akira  <akr@f...>
+
+	* process.c (has_privilege): New function.
+	  (retry_fork_async_signal_safe): Don't use vfork() for privileged
+	  process.
+
+	* configure.in (getresuid): Check function.
+	  (getresgid): Ditto.
+
 Thu Sep  4 20:22:14 2014  Laurent Arnoud  <laurent@s...>
 
 	* test/pathname/test_pathname.rb: added testcase for Pathname#mountpoint.
Index: process.c
===================================================================
--- process.c	(revision 47385)
+++ process.c	(revision 47386)
@@ -3277,6 +3277,72 @@ recv_child_error(int fd, int *errp, char https://github.com/ruby/ruby/blob/trunk/process.c#L3277
     return size != 0;
 }
 
+static int
+has_privilege(void)
+{
+    /*
+     * has_privilege() is used to choose vfork() or fork().
+     *
+     * If the process has privilege, the parent process or
+     * the child process can change UID/GID.
+     * If vfork() is used to create the child process and
+     * the parent or child process change effective UID/GID,
+     * different privileged processes shares memory.
+     * It is a bad situation.
+     * So, fork() should be used.
+     */
+
+    rb_uid_t ruid, euid;
+    rb_gid_t rgid, egid;
+
+#if defined HAVE_ISSETUGID
+    if (issetugid())
+	return 1;
+#endif
+
+#ifdef HAVE_GETRESUID
+    {
+        int ret;
+        rb_uid_t suid;
+        ret = getresuid(&ruid, &euid, &suid);
+        if (ret == -1)
+            rb_sys_fail("getresuid(2)");
+        if (ruid != suid)
+            return 1;
+    }
+#else
+    {
+        rb_uid_t ruid = getuid();
+        rb_uid_t euid = geteuid();
+    }
+#endif
+
+    if (ruid == 0 || ruid != euid)
+        return 1;
+
+#ifdef HAVE_GETRESGID
+    {
+        int ret;
+        rb_gid_t sgid;
+        ret = getresgid(&rgid, &egid, &sgid);
+        if (ret == -1)
+            rb_sys_fail("getresgid(2)");
+        if (rgid != sgid)
+            return 0;
+    }
+#else
+    {
+        rb_gid_t rgid = getgid();
+        rb_gid_t egid = getegid();
+    }
+#endif
+
+    if (rgid == 0 || rgid != egid)
+        return 1;
+
+    return 0;
+}
+
 static rb_pid_t
 retry_fork_async_signal_safe(int *status, int *ep,
         int (*chfunc)(void*, char *, size_t), void *charg,
@@ -3289,7 +3355,10 @@ retry_fork_async_signal_safe(int *status https://github.com/ruby/ruby/blob/trunk/process.c#L3355
     while (1) {
         prefork();
 #ifdef HAVE_WORKING_VFORK
-        pid = vfork();
+        if (!has_privilege())
+            pid = vfork();
+        else
+            pid = fork();
 #else
         pid = fork();
 #endif

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