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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.