VACCESS_ACL_NFS4(9)    FreeBSD Kernel Developer's Manual   VACCESS_ACL_NFS4(9)

NAME
     vaccess_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
     security mechanisms whose results will be composed with the return value.

     The algorithm used by vaccess_acl_nfs4() is based on the NFSv4 ACL
     evaluation 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
     compared 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 VALUES
     vaccess_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
                        permissions.

     [EPERM]            Operation not permitted.  An attempt was made to
                        perform an operation limited to processes with
                        appropriate privileges or to the owner of a file or
                        other resource.

SEE ALSO
     vaccess(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
     evaluation algorithm, or cross reference another page that does.

FreeBSD 13.1-RELEASE-p6       September 18, 2009       FreeBSD 13.1-RELEASE-p6