svn commit: r349320 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Sun Jun 23 18:35:11 2019
New Revision: 349320
URL: https://svnweb.freebsd.org/changeset/base/349320

Log:
  coredump: avoid writing to core files not owned by the real user.
  
  Reported by: blake frantz <trew at hick.org>
  PR:	68905
  admbugs:	358
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/kern/kern_sig.c

Modified: head/sys/kern/kern_sig.c
==============================================================================
--- head/sys/kern/kern_sig.c	Sun Jun 23 17:39:13 2019	(r349319)
+++ head/sys/kern/kern_sig.c	Sun Jun 23 18:35:11 2019	(r349320)
@@ -3597,10 +3597,11 @@ coredump(struct thread *td)
 
 	/*
 	 * Don't dump to non-regular files or files with links.
-	 * Do not dump into system files.
+	 * Do not dump into system files. Real user must own the corefile.
 	 */
 	if (vp->v_type != VREG || VOP_GETATTR(vp, &vattr, cred) != 0 ||
-	    vattr.va_nlink != 1 || (vp->v_vflag & VV_SYSTEM) != 0) {
+	    vattr.va_nlink != 1 || (vp->v_vflag & VV_SYSTEM) != 0 ||
+	    vattr.va_uid != cred->cr_ruid) {
 		VOP_UNLOCK(vp, 0);
 		error = EFAULT;
 		goto out;