1 files changed, 59 insertions, 1 deletions

diff --git a/sys/fs/devfs/devfs_vnops.c b/sys/fs/devfs/devfs_vnops.c
index 09a978a..dbce518 100644
--- a/sys/fs/devfs/devfs_vnops.c
+++ b/sys/fs/devfs/devfs_vnops.c
@@ -61,6 +61,7 @@
 #include <sys/proc.h>
 #include <sys/stat.h>
 #include <sys/sx.h>
+#include <sys/sysctl.h>
 #include <sys/time.h>
 #include <sys/ttycom.h>
 #include <sys/unistd.h>
@@ -113,6 +114,25 @@ static vop_symlink_t	devfs_symlink;
 extern struct vop_vector devfs_vnodeops;
 extern struct vop_vector devfs_specops;
 
+static u_int
+devfs_random(void)
+{
+	static u_int devfs_seed;
+
+	while (devfs_seed == 0) {
+		/*
+		 * Make sure people don't make stupid assumptions
+		 * about device major/minor numbers in userspace.
+		 * We do this late to get entropy and for the same
+		 * reason we force a reseed, but it may not be
+		 * late enough for entropy to be available.
+		 */
+		arc4rand(&devfs_seed, sizeof devfs_seed, 1);
+		devfs_seed &= 0xf0f;
+	}
+	return (devfs_seed);
+}
+
 static int
 devfs_fp_check(struct file *fp, struct cdev **devp, struct cdevsw **dswp)
 {
@@ -441,7 +461,8 @@ devfs_getattr(ap)
 		vap->va_mtime = dev->si_mtime;
 		fix(dev->si_ctime);
 		vap->va_ctime = dev->si_ctime;
-		vap->va_rdev = dev->si_udev;
+
+		vap->va_rdev = de->de_inode ^ devfs_random();
 	}
 	vap->va_gen = 0;
 	vap->va_flags = 0;
@@ -1432,6 +1453,43 @@ static struct vop_vector devfs_specops = {
 	.vop_write =		VOP_PANIC,
 };
 
+dev_t
+dev2udev(struct cdev *x)
+{
+	if (x == NULL)
+		return (NODEV);
+	return (x->si_inode ^ devfs_random());
+}
+
+/*
+ * Helper sysctl for devname(3).  We're given a struct cdev * and return
+ * the name, if any, registered by the device driver.
+ */
+static int
+sysctl_devname(SYSCTL_HANDLER_ARGS)
+{
+	int error;
+	dev_t ud;
+	struct cdev *dev, **dp;
+
+	error = SYSCTL_IN(req, &ud, sizeof (ud));
+	if (error)
+		return (error);
+	if (ud == NODEV)
+		return(EINVAL);
+	dp = devfs_itod(ud ^ devfs_random());
+	if (dp == NULL)
+		return(ENOENT);
+	dev = *dp;
+	if (dev == NULL)
+		return(ENOENT);
+	return(SYSCTL_OUT(req, dev->si_name, strlen(dev->si_name) + 1));
+	return (error);
+}
+
+SYSCTL_PROC(_kern, OID_AUTO, devname, CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY,
+	NULL, 0, sysctl_devname, "", "devname(3) handler");
+
 /*
  * Our calling convention to the device drivers used to be that we passed
  * vnode.h IO_* flags to read()/write(), but we're moving to fcntl.h O_