X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/blobdiff_plain/9f7857db2a95d07dfda6ef655e42d72cfd4e740c..8583490d0022d6efbaf5c6bf8abc3a426861e69b:/usr/src/sys/miscfs/union/union_vfsops.c?ds=inline

diff --git a/usr/src/sys/miscfs/union/union_vfsops.c b/usr/src/sys/miscfs/union/union_vfsops.c
index 9346c2391c..8bb8cb0017 100644
--- a/usr/src/sys/miscfs/union/union_vfsops.c
+++ b/usr/src/sys/miscfs/union/union_vfsops.c
@@ -8,7 +8,7 @@
  *
  * %sccs.include.redist.c%
  *
- *	@(#)union_vfsops.c	8.6 (Berkeley) %G%
+ *	@(#)union_vfsops.c	8.14 (Berkeley) %G%
  */
 
 /*
@@ -43,7 +43,7 @@ union_mount(mp, path, data, ndp, p)
 	struct union_args args;
 	struct vnode *lowerrootvp = NULLVP;
 	struct vnode *upperrootvp = NULLVP;
-	struct union_mount *um;
+	struct union_mount *um = 0;
 	struct ucred *cred = 0;
 	struct ucred *scred;
 	struct vattr va;
@@ -68,34 +68,6 @@ union_mount(mp, path, data, ndp, p)
 		goto bad;
 	}
 
-	/*
-	 * Take a copy of the process's credentials.  This isn't
-	 * quite right since the euid will always be zero and we
-	 * want to get the "real" users credentials.  So fix up
-	 * the uid field after taking the copy.
-	 */
-	cred = crdup(p->p_ucred);
-	cred->cr_uid = p->p_cred->p_ruid;
-
-	/*
-	 * Ensure the *real* user has write permission on the
-	 * mounted-on directory.  This allows the mount_union
-	 * command to be made setuid root so allowing anyone
-	 * to do union mounts onto any directory on which they
-	 * have write permission and which they also own.
-	 */
-	error = VOP_GETATTR(mp->mnt_vnodecovered, &va, cred, p);
-	if (error)
-		goto bad;
-	if ((va.va_uid != cred->cr_uid) && 
-	    (cred->cr_uid != 0)) {
-		error = EACCES;
-		goto bad;
-	}
-	error = VOP_ACCESS(mp->mnt_vnodecovered, VWRITE, cred, p);
-	if (error)
-		goto bad;
-
 	/*
 	 * Get argument
 	 */
@@ -106,18 +78,10 @@ union_mount(mp, path, data, ndp, p)
 	VREF(lowerrootvp);
 
 	/*
-	 * Find upper node.  Use the real process credentials,
-	 * not the effective ones since this will have come
-	 * through a setuid process (mount_union).  All this
-	 * messing around with permissions is entirely bogus
-	 * and should be removed by allowing any user straight
-	 * past the mount system call.
+	 * Find upper node.
 	 */
-	scred = p->p_ucred;
-	p->p_ucred = cred;
 	NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT,
 	       UIO_USERSPACE, args.target, p);
-	p->p_ucred = scred;
 
 	if (error = namei(ndp))
 		goto bad;
@@ -167,7 +131,18 @@ union_mount(mp, path, data, ndp, p)
 		goto bad;
 	}
 
-	um->um_cred = cred;
+	/*
+	 * Unless the mount is readonly, ensure that the top layer
+	 * supports whiteout operations
+	 */
+	if ((mp->mnt_flag & MNT_RDONLY) == 0) {
+		error = VOP_WHITEOUT(um->um_uppervp, (struct componentname *) 0, LOOKUP);
+		if (error)
+			goto bad;
+	}
+
+	um->um_cred = p->p_ucred;
+	crhold(um->um_cred);
 	um->um_cmode = UN_DIRMODE &~ p->p_fd->fd_cmask;
 
 	/*
@@ -195,12 +170,6 @@ union_mount(mp, path, data, ndp, p)
 	 */
 	mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY);
 
-	/*
-	 * This is a user mount.  Privilege check for unmount
-	 * will be done in union_unmount.
-	 */
-	mp->mnt_flag |= MNT_USER;
-
 	mp->mnt_data = (qaddr_t) um;
 	getnewfsid(mp, MOUNT_UNION);
 
@@ -209,13 +178,13 @@ union_mount(mp, path, data, ndp, p)
 
 	switch (um->um_op) {
 	case UNMNT_ABOVE:
-		cp = "un-above:";
+		cp = "<above>:";
 		break;
 	case UNMNT_BELOW:
-		cp = "un-below:";
+		cp = "<below>:";
 		break;
 	case UNMNT_REPLACE:
-		cp = "replace:";
+		cp = "";
 		break;
 	}
 	len = strlen(cp);
@@ -234,6 +203,8 @@ union_mount(mp, path, data, ndp, p)
 	return (0);
 
 bad:
+	if (um)
+		free(um, M_UFSMNT);
 	if (cred)
 		crfree(cred);
 	if (upperrootvp)
@@ -270,6 +241,7 @@ union_unmount(mp, mntflags, p)
 	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
 	struct vnode *um_rootvp;
 	int error;
+	int freeing;
 	int flags = 0;
 	extern int doforce;
 
@@ -277,11 +249,6 @@ union_unmount(mp, mntflags, p)
 	printf("union_unmount(mp = %x)\n", mp);
 #endif
 
-	/* only the mounter, or superuser can unmount */
-	if ((p->p_cred->p_ruid != um->um_cred->cr_uid) &&
-	    (error = suser(p->p_ucred, &p->p_acflag)))
-		return (error);
-
 	if (mntflags & MNT_FORCE) {
 		/* union can never be rootfs so don't check for it */
 		if (!doforce)
@@ -291,17 +258,42 @@ union_unmount(mp, mntflags, p)
 
 	if (error = union_root(mp, &um_rootvp))
 		return (error);
+
+	/*
+	 * Keep flushing vnodes from the mount list.
+	 * This is needed because of the un_pvp held
+	 * reference to the parent vnode.
+	 * If more vnodes have been freed on a given pass,
+	 * the try again.  The loop will iterate at most
+	 * (d) times, where (d) is the maximum tree depth
+	 * in the filesystem.
+	 */
+	for (freeing = 0; vflush(mp, um_rootvp, flags) != 0;) {
+		struct vnode *vp;
+		int n;
+
+		/* count #vnodes held on mount list */
+		for (n = 0, vp = mp->mnt_vnodelist.lh_first;
+				vp != NULLVP;
+				vp = vp->v_mntvnodes.le_next)
+			n++;
+
+		/* if this is unchanged then stop */
+		if (n == freeing)
+			break;
+
+		/* otherwise try once more time */
+		freeing = n;
+	}
+
+	/* At this point the root vnode should have a single reference */
 	if (um_rootvp->v_usecount > 1) {
 		vput(um_rootvp);
 		return (EBUSY);
 	}
-	if (error = vflush(mp, um_rootvp, flags)) {
-		vput(um_rootvp);
-		return (error);
-	}
 
 #ifdef UNION_DIAGNOSTIC
-	vprint("alias root of lower", um_rootvp);
+	vprint("union root", um_rootvp);
 #endif	 
 	/*
 	 * Discard references to upper and lower target vnodes.
@@ -335,12 +327,6 @@ union_root(mp, vpp)
 	int error;
 	int loselock;
 
-#ifdef UNION_DIAGNOSTIC
-	printf("union_root(mp = %x, lvp = %x, uvp = %x)\n", mp,
-			um->um_lowervp,
-			um->um_uppervp);
-#endif
-
 	/*
 	 * Return locked reference to root.
 	 */
@@ -359,7 +345,8 @@ union_root(mp, vpp)
 			      (struct vnode *) 0,
 			      (struct componentname *) 0,
 			      um->um_uppervp,
-			      um->um_lowervp);
+			      um->um_lowervp,
+			      1);
 
 	if (error) {
 		if (!loselock)
@@ -368,7 +355,6 @@ union_root(mp, vpp)
 		if (um->um_lowervp)
 			vrele(um->um_lowervp);
 	} else {
-		(*vpp)->v_flag |= VROOT;
 		if (loselock)
 			VTOUNION(*vpp)->un_flags &= ~UN_ULOCK;
 	}
@@ -442,16 +428,20 @@ union_statfs(mp, sbp, p)
 	 * kind of sense.  none of this makes sense though.
 	 */
 
-	if (mstat.f_bsize != lbsize) {
+	if (mstat.f_bsize != lbsize)
 		sbp->f_blocks = sbp->f_blocks * lbsize / mstat.f_bsize;
-		sbp->f_bfree = sbp->f_bfree * lbsize / mstat.f_bsize;
-		sbp->f_bavail = sbp->f_bavail * lbsize / mstat.f_bsize;
-	}
+
+	/*
+	 * The "total" fields count total resources in all layers,
+	 * the "free" fields count only those resources which are
+	 * free in the upper layer (since only the upper layer
+	 * is writeable).
+	 */
 	sbp->f_blocks += mstat.f_blocks;
-	sbp->f_bfree += mstat.f_bfree;
-	sbp->f_bavail += mstat.f_bavail;
+	sbp->f_bfree = mstat.f_bfree;
+	sbp->f_bavail = mstat.f_bavail;
 	sbp->f_files += mstat.f_files;
-	sbp->f_ffree += mstat.f_ffree;
+	sbp->f_ffree = mstat.f_ffree;
 
 	if (sbp != &mp->mnt_stat) {
 		bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));