svn commit: r194586 - in head/sys: cddl/compat/opensolaris/kern cddl/compat/opensolaris/sys cddl/contrib/opensolaris/uts/common/fs/zfs kern sys

[Bruce Evans]

On Sun, 21 Jun 2009, Konstantin Belousov wrote:

> Log:
>  Add another flags argument to vn_open_cred. Use it to specify that some
>  vn_open_cred invocations shall not audit namei path.

> Modified: head/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
> ==============================================================================
> --- head/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c	Sun Jun 21 13:15:56 2009	(r194585)
> +++ head/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c	Sun Jun 21 13:41:32 2009	(r194586)
> @@ -85,7 +85,8 @@ kobj_open_file_vnode(const char *file)
>
> 	flags = FREAD;
> 	NDINIT(&nd, LOOKUP, MPSAFE, UIO_SYSSPACE, file, td);
> -	error = vn_open_cred(&nd, &flags, O_NOFOLLOW, curthread->td_ucred, NULL);
> +	error = vn_open_cred(&nd, &flags, O_NOFOLLOW, 0, curthread->td_ucred,
> +	    NULL);

I was going to ask "why not put the flag in the existing flags arg,
like O_NOFOLLOW here?", but it seems that there is no existing flags
arg and the above O_NOFOLLOW is garbage.  O_NOFOLLOW happens to be
0x100, so I think the above asks for mode S_IRUSR.

Now I will ask "why not put O_NOFOLLOW here and the new flag in the
existing pointer-to-flags arg?".

> Modified: head/sys/cddl/compat/opensolaris/sys/vnode.h
> ==============================================================================
> --- head/sys/cddl/compat/opensolaris/sys/vnode.h	Sun Jun 21 13:15:56 2009	(r194585)
> +++ head/sys/cddl/compat/opensolaris/sys/vnode.h	Sun Jun 21 13:41:32 2009	(r194586)
> @@ -182,7 +182,7 @@ vn_openat(char *pnamep, enum uio_seg seg
> 		vref(startvp);
> 	NDINIT_ATVP(&nd, operation, MPSAFE, UIO_SYSSPACE, pnamep, startvp, td);
> 	filemode |= O_NOFOLLOW;
> -	error = vn_open_cred(&nd, &filemode, createmode, td->td_ucred, NULL);
> +	error = vn_open_cred(&nd, &filemode, createmode, 0, td->td_ucred, NULL);

Here it does put O_NOFOLLOW in the existing pointer-to-flags arg.  It
obfuscates the open-flags variable by naming it filemode.

> Modified: head/sys/kern/vfs_vnops.c
> ==============================================================================
> --- head/sys/kern/vfs_vnops.c	Sun Jun 21 13:15:56 2009	(r194585)
> +++ head/sys/kern/vfs_vnops.c	Sun Jun 21 13:41:32 2009	(r194586)
> @@ -102,11 +102,8 @@ vn_open(ndp, flagp, cmode, fp)
>  * due to the NDINIT being done elsewhere.
>  */
> int
> -vn_open_cred(ndp, flagp, cmode, cred, fp)
> -	struct nameidata *ndp;
> -	int *flagp, cmode;
> -	struct ucred *cred;
> -	struct file *fp;
> +vn_open_cred(struct nameidata *ndp, int *flagp, int cmode, u_int vn_open_flags,
> +    struct ucred *cred, struct file *fp)
> {
> 	struct vnode *vp;
> 	struct mount *mp;
> @@ -124,9 +121,11 @@ restart:
> 	if (fmode & O_CREAT) {

Internally, flags are obfuscated by copying *flagp to the misnamed local
variable fmode.

The pointer-to-flags variable has about 12 spare bits in it.  It already
has just 1 kernel-only flag (O_HASLOCK, misnamed FHASLOCK and misassigned
in the middle of the user flags).  fcntl.h's list of open flags has
been obfuscated by putting AT_ flags in the middle of the list.

Bruce