NAME

     vaccess_acl_posix1e — generate a POSIX.1e ACL access control decision using vnode parameters

SYNOPSIS

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

     int
     vaccess_acl_posix1e(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 POSIX.1e
     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_posix1e() 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_posix1e() is based on the POSIX.1e ACL evaluation
     algorithm.  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_posix1e() 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

     This manual page and the current implementation of vaccess_acl_posix1e() were written by
     Robert Watson.

BUGS

     This manual page should include a full description of the POSIX.1e ACL evaluation algorithm,
     or cross reference another page that does.