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     vaccess_acl_nfs4 — generate a NFSv4 ACL access control decision using vnode parameters


     #include <sys/param.h>
     #include <sys/vnode.h>
     #include <sys/acl.h>

     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);


     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


     vaccess_acl_nfs4() will return 0 on success, or a non-zero error value on failure.


     [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.


     vaccess(9), vnode(9), VOP_ACCESS(9)


     Current implementation of vaccess_acl_nfs4() was written by Edward Tomasz Napierala


     This manual page should include a full description of the NFSv4 ACL evaluation algorithm, or
     cross reference another page that does.