From 3fe65eb8fe59a17f65ff667b8aa30d543d62b221 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Tue, 12 May 2009 09:28:45 +0000
Subject: [PATCH] Report all fdescfs vnodes as VCHR for stat(2). Fake the
 unique major/minor numbers of the devices.

Pretending that the vnodes are character devices prevents file tree
walkers from descending into the directories opened by current process.
Also, not doing stat on the filedescriptors prevents the recursive entry
into the VFS.

Requested by:	kientzle
Discussed with:	Jilles Tjoelker <jilles stack nl>
---
 sys/fs/fdescfs/fdesc_vnops.c | 85 +++++++++---------------------------
 1 file changed, 20 insertions(+), 65 deletions(-)

diff --git a/sys/fs/fdescfs/fdesc_vnops.c b/sys/fs/fdescfs/fdesc_vnops.c
index 4474b176577..07b2547b175 100644
--- a/sys/fs/fdescfs/fdesc_vnops.c
+++ b/sys/fs/fdescfs/fdesc_vnops.c
@@ -389,78 +389,34 @@ fdesc_getattr(ap)
 {
 	struct vnode *vp = ap->a_vp;
 	struct vattr *vap = ap->a_vap;
-	struct thread *td = curthread;
-	struct file *fp;
-	struct stat stb;
-	u_int fd;
-	int error = 0;
+
+	vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
+	vap->va_fileid = VTOFDESC(vp)->fd_ix;
+	vap->va_uid = 0;
+	vap->va_gid = 0;
+	vap->va_blocksize = DEV_BSIZE;
+	vap->va_atime.tv_sec = boottime.tv_sec;
+	vap->va_atime.tv_nsec = 0;
+	vap->va_mtime = vap->va_atime;
+	vap->va_ctime = vap->va_mtime;
+	vap->va_gen = 0;
+	vap->va_flags = 0;
+	vap->va_bytes = 0;
+	vap->va_filerev = 0;
 
 	switch (VTOFDESC(vp)->fd_type) {
 	case Froot:
-		vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
 		vap->va_type = VDIR;
 		vap->va_nlink = 2;
 		vap->va_size = DEV_BSIZE;
-		vap->va_fileid = VTOFDESC(vp)->fd_ix;
-		vap->va_uid = 0;
-		vap->va_gid = 0;
-		vap->va_blocksize = DEV_BSIZE;
-		vap->va_atime.tv_sec = boottime.tv_sec;
-		vap->va_atime.tv_nsec = 0;
-		vap->va_mtime = vap->va_atime;
-		vap->va_ctime = vap->va_mtime;
-		vap->va_gen = 0;
-		vap->va_flags = 0;
 		vap->va_rdev = NODEV;
-		vap->va_bytes = 0;
-		vap->va_filerev = 0;
 		break;
 
 	case Fdesc:
-		fd = VTOFDESC(vp)->fd_fd;
-
-		if ((error = fget(td, fd, &fp)) != 0)
-			return (error);
-
-		bzero(&stb, sizeof(stb));
-		error = fo_stat(fp, &stb, td->td_ucred, td);
-		fdrop(fp, td);
-		if (error == 0) {
-			vap->va_type = IFTOVT(stb.st_mode);
-			vap->va_mode = stb.st_mode;
-			if (vap->va_type == VDIR)
-				vap->va_mode &= ~(S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
-			vap->va_nlink = 1;
-			vap->va_flags = 0;
-			vap->va_bytes = stb.st_blocks * stb.st_blksize;
-			vap->va_fileid = VTOFDESC(vp)->fd_ix;
-			vap->va_size = stb.st_size;
-			vap->va_blocksize = stb.st_blksize;
-			vap->va_rdev = stb.st_rdev;
-
-			/*
-			 * If no time data is provided, use the current time.
-			 */
-			if (stb.st_atimespec.tv_sec == 0 &&
-			    stb.st_atimespec.tv_nsec == 0)
-				nanotime(&stb.st_atimespec);
-
-			if (stb.st_ctimespec.tv_sec == 0 &&
-			    stb.st_ctimespec.tv_nsec == 0)
-				nanotime(&stb.st_ctimespec);
-
-			if (stb.st_mtimespec.tv_sec == 0 &&
-			    stb.st_mtimespec.tv_nsec == 0)
-				nanotime(&stb.st_mtimespec);
-
-			vap->va_atime = stb.st_atimespec;
-			vap->va_mtime = stb.st_mtimespec;
-			vap->va_ctime = stb.st_ctimespec;
-			vap->va_uid = stb.st_uid;
-			vap->va_gid = stb.st_gid;
-			vap->va_gen = 0;
-			vap->va_filerev = 0;
-		}
+		vap->va_type = VCHR;
+		vap->va_nlink = 1;
+		vap->va_size = 0;
+		vap->va_rdev = makedev(0, vap->va_fileid);
 		break;
 
 	default:
@@ -468,9 +424,8 @@ fdesc_getattr(ap)
 		break;
 	}
 
-	if (error == 0)
-		vp->v_type = vap->va_type;
-	return (error);
+	vp->v_type = vap->va_type;
+	return (0);
 }
 
 static int