VACCESS_ACL_NFS4(9) BSD Kernel Developer's Manual VACCESS_ACL_NFS4(9)NAMEvaccess_acl_nfs4 — generate a NFSv4 ACL access control decision using
vnode parameters
SYNOPSIS
#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/acl.h>
int
vaccess_acl_nfs4(enum vtype type, uid_t file_uid, gid_t file_gid,
struct acl *acl, accmode_t accmode, struct ucred *cred,
int *privused);
DESCRIPTION
This call implements the logic for the UNIX discretionary file security
model with NFSv4 ACL extensions. It accepts the vnodes type type, owning
UID file_uid, owning GID file_gid, access ACL for the file acl, desired
access mode accmode, requesting credential cred, and an optional call-by-
reference int pointer returning whether or not privilege was required for
successful evaluation of the call; the privused pointer may be set to
NULL by the caller in order not to be informed of privilege information,
or it may point to an integer that will be set to 1 if privilege is used,
and 0 otherwise.
This call is intended to support implementations of VOP_ACCESS(9), which
will use their own access methods to retrieve the vnode properties, and
then invoke vaccess_acl_nfs4() in order to perform the actual check.
Implementations of VOP_ACCESS(9) may choose to implement additional secu‐
rity mechanisms whose results will be composed with the return value.
The algorithm used by vaccess_acl_nfs4() is based on the NFSv4 ACL evalu‐
ation algorithm, as described in NFSv4 Minor Version 1, draft-ietf-
nfsv4-minorversion1-21.txt. The algorithm selects a matching entry from
the access ACL, which may then be composed with an available ACL mask
entry, providing UNIX security compatibility.
Once appropriate protections are selected for the current credential, the
requested access mode, in combination with the vnode type, will be com‐
pared with the discretionary rights available for the credential. If the
rights granted by discretionary protections are insufficient, then super-
user privilege, if available for the credential, will also be considered.
RETURN VALUESvaccess_acl_nfs4() will return 0 on success, or a non-zero error value on
failure.
ERRORS
[EACCES] Permission denied. An attempt was made to access a
file in a way forbidden by its file access permis‐
sions.
[EPERM] Operation not permitted. An attempt was made to per‐
form an operation limited to processes with appropri‐
ate privileges or to the owner of a file or other
resource.
SEE ALSOvaccess(9), vnode(9), VOP_ACCESS(9)AUTHORS
Current implementation of vaccess_acl_nfs4() was written by Edward Tomasz
Napierala ⟨trasz@FreeBSD.org⟩.
BUGS
This manual page should include a full description of the NFSv4 ACL eval‐
uation algorithm, or cross reference another page that does.
BSD September 18, 2009 BSD
