svn commit: r221012 - head/bin/sh

[Jilles Tjoelker]

Author: jilles
Date: Mon Apr 25 10:14:29 2011
New Revision: 221012
URL: http://svn.freebsd.org/changeset/base/221012

Log:
  sh: Check setuid()/setgid() return values.
  
  If the -p option is turned off, privileges from a setuid or setgid binary
  are dropped. Make sure to check if this succeeds. If it fails, this is an
  error which will cause the shell to abort except in interactive mode or if
  'command' was used to make 'set' or an outer 'eval' or '.' non-special.
  
  Note that taking advantage of this feature and writing setuid shell scripts
  seems unwise.
  
  MFC after:	1 week

Modified:
  head/bin/sh/options.c

Modified: head/bin/sh/options.c
==============================================================================
--- head/bin/sh/options.c	Mon Apr 25 10:08:34 2011	(r221011)
+++ head/bin/sh/options.c	Mon Apr 25 10:14:29 2011	(r221012)
@@ -280,8 +280,10 @@ setoption(int flag, int val)
 	int i;
 
 	if (flag == 'p' && !val && privileged) {
-		(void) setuid(getuid());
-		(void) setgid(getgid());
+		if (setgid(getgid()) == -1)
+			error("setgid");
+		if (setuid(getuid()) == -1)
+			error("setuid");
 	}
 	for (i = 0; i < NOPTS; i++)
 		if (optlist[i].letter == flag) {