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From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To: Bruce Evans <bde@zeta.org.au>
References: <23727599.post@talk.nabble.com> <86prdvipwe.fsf@ds4.des.no>
	<20090527233110.E4243@delplex.bde.org> <86r5yaijef.fsf@ds4.des.no>
	<20090529210855.V1643@besplex.bde.org> <86vdnju9z1.fsf@ds4.des.no>
Date: Fri, 29 May 2009 18:58:08 +0200
In-Reply-To: <86vdnju9z1.fsf@ds4.des.no> ("Dag-Erling =?utf-8?Q?Sm=C3=B8rg?=
	=?utf-8?Q?rav=22's?= message of "Fri, 29 May 2009 18:53:22 +0200")
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Cc: freebsd-hackers@FreeBSD.org, Jakub Lach <jakub_lach@mailplus.pl>
Subject: Re: FYI Lighttpd 1.4.23 /kernel (trailing '/' on regular file
	symlink) vulnerability
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How's this?

Index: sys/kern/vfs_lookup.c
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
--- sys/kern/vfs_lookup.c	(revision 193028)
+++ sys/kern/vfs_lookup.c	(working copy)
@@ -454,7 +454,6 @@
 	int docache;			/* =3D=3D 0 do not cache last component */
 	int wantparent;			/* 1 =3D> wantparent or lockparent flag */
 	int rdonly;			/* lookup read-only flag bit */
-	int trailing_slash;
 	int error =3D 0;
 	int dpunlocked =3D 0;		/* dp has already been unlocked */
 	struct componentname *cnp =3D &ndp->ni_cnd;
@@ -529,12 +528,10 @@
 	 * trailing slashes to handle symlinks, existing non-directories
 	 * and non-existing files that won't be directories specially later.
 	 */
-	trailing_slash =3D 0;
 	while (*cp =3D=3D '/' && (cp[1] =3D=3D '/' || cp[1] =3D=3D '\0')) {
 		cp++;
 		ndp->ni_pathlen--;
 		if (*cp =3D=3D '\0') {
-			trailing_slash =3D 1;
 			*ndp->ni_next =3D '\0';	/* XXX for direnter() ... */
 			cnp->cn_flags |=3D TRAILINGSLASH;
 		}
@@ -711,7 +708,7 @@
 			error =3D EROFS;
 			goto bad;
 		}
-		if (*cp =3D=3D '\0' && trailing_slash &&
+		if (*cp =3D=3D '\0' && (cnp->cn_flags & TRAILINGSLASH) &&
 		     !(cnp->cn_flags & WILLBEDIR)) {
 			error =3D ENOENT;
 			goto bad;
@@ -788,7 +785,7 @@
 	 * Check for symbolic link
 	 */
 	if ((dp->v_type =3D=3D VLNK) &&
-	    ((cnp->cn_flags & FOLLOW) || trailing_slash ||
+	    ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) ||
 	     *ndp->ni_next =3D=3D '/')) {
 		cnp->cn_flags |=3D ISSYMLINK;
 		if (dp->v_iflag & VI_DOOMED) {

BTW, what does the "XXX for direnter()" comment mean?

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no