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 acc_mode, requesting credential cred, and an optional call-by-reference
.Vt 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.
vaccess_acl_posix1e will return 0 on success, or a non-zero error value on failure.