svn commit: r257123 - in stable/10/sys: kern sys

[Konstantin Belousov]

Author: kib
Date: Fri Oct 25 16:36:16 2013
New Revision: 257123
URL: http://svnweb.freebsd.org/changeset/base/257123

Log:
  MFC r256504:
  Add a sysctl kern.disallow_high_osrel which disables executing the
  images compiled on the world with higher major version number than the
  high version number of the booted kernel.  Default to disable.
  
  Approved by:	re (glebius)

Modified:
  stable/10/sys/kern/kern_exec.c
  stable/10/sys/sys/param.h
Directory Properties:
  stable/10/sys/   (props changed)

Modified: stable/10/sys/kern/kern_exec.c
==============================================================================
--- stable/10/sys/kern/kern_exec.c	Fri Oct 25 16:33:24 2013	(r257122)
+++ stable/10/sys/kern/kern_exec.c	Fri Oct 25 16:36:16 2013	(r257123)
@@ -123,6 +123,11 @@ u_long ps_arg_cache_limit = PAGE_SIZE / 
 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 
     &ps_arg_cache_limit, 0, "");
 
+static int disallow_high_osrel;
+SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW,
+    &disallow_high_osrel, 0,
+    "Disallow execution of binaries built for higher version of the world");
+
 static int map_at_zero = 0;
 TUNABLE_INT("security.bsd.map_at_zero", &map_at_zero);
 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RW, &map_at_zero, 0,
@@ -552,6 +557,15 @@ interpret:
 	     vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0))
 		imgp->execpath = args->fname;
 
+	if (disallow_high_osrel &&
+	    P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) {
+		error = ENOEXEC;
+		uprintf("Osrel %d for image %s too high\n", p->p_osrel,
+		    imgp->execpath != NULL ? imgp->execpath : "<unresolved>");
+		vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
+		goto exec_fail_dealloc;
+	}
+
 	/*
 	 * Copy out strings (args and env) and initialize stack base
 	 */

Modified: stable/10/sys/sys/param.h
==============================================================================
--- stable/10/sys/sys/param.h	Fri Oct 25 16:33:24 2013	(r257122)
+++ stable/10/sys/sys/param.h	Fri Oct 25 16:36:16 2013	(r257123)
@@ -80,6 +80,8 @@
 #define	P_OSREL_SIGWAIT		700000
 #define	P_OSREL_SIGSEGV		700004
 #define	P_OSREL_MAP_ANON	800104
+
+#define	P_OSREL_MAJOR(x)	((x) / 100000)
 #endif
 
 #ifndef LOCORE