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GENFS_CAN_ACCESS_ACL_NFS4(9)                         Kernel Developer's Manual

     genfs_can_access_acl_nfs4 - generate a NFSv4 ACL access control decision
     using vnode parameters

     #include <miscfs/genfs/genfs.h>

          genfs_can_access_acl_nfs4(struct vnode *, kauth_cred_t, uid_t,
              mode_t, struct acl *, accmode_t) struct vnode *vp,
         kath_cred_t cred, uid_t file_uid, gid_t file_gid, mode_t file_mode,
         struct acl *acl, accmode_t accmode);

     This call implements the logic for the UNIX discretionary file security
     model with NFSv4 ACL extensions.  It accepts the vnode vp, requesting
     credential cred, owning UID file_uid, owning GID file_gid, file
     permissions file_mode, access ACL for the file acl, desired access mode

     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 genfs_can_access_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 genfs_can_access_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

     genfs_can_access_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

     [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.

     genfs_can_access(9), vnode(9), VOP_ACCESS(9)

     Current implementation of genfs_can_access_acl_nfs4() was written by
     Edward Tomasz Napierala <trasz@FreeBSD.org>.

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

NetBSD 9.99                   September 18, 2009                   NetBSD 9.99