1.\" Copyright 2019 The FreeBSD Foundation. 2.\" 3.\" This software was developed by Bora Ozarslan under sponsorship from 4.\" the FreeBSD Foundation. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' 16.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.Dd October 5, 2023 28.Dt ELFCTL 1 29.Os 30.Sh NAME 31.Nm elfctl 32.Nd change an ELF binary's feature control note 33.Sh SYNOPSIS 34.Nm 35.Op Fl h | Fl -help 36.Op Fl i 37.Op Fl l 38.Op Fl e Ar featurelist 39.Ar 40.Sh DESCRIPTION 41The 42.Nm 43utility modifies feature flags in the feature control note in an ELF binary. 44.Pp 45The options are as follows: 46.Bl -tag -width indent 47.It Fl h | Fl -help 48Print a usage message and exit. 49.It Fl i 50Ignore unknown feature flags in 51.Ar featurelist . 52.It Fl l 53List known ELF feature flags. 54.It Fl e Ar featurelist 55Edit features from the given comma separated list 56.Ar featurelist . 57.Ar featurelist 58starts with one of the three operations: 59.Dq Li + 60to turn on the features, 61.Dq Li - 62to turn off the features, 63.Dq Li = 64to only turn on the given features. 65A comma separated list of feature names or numeric values follows the 66operation. 67.El 68.Pp 69If 70.Fl e 71is not specified 72.Nm 73displays the status of each feature in the ELF note in each 74.Ar . 75.Sh EXIT STATUS 76Exit status is 0 on success, and 1 if the command 77fails if a file does not exist, is too short, 78or fails to find or edit features note. 79.Sh EXAMPLES 80The following is an example of a typical usage 81of the 82.Nm 83command: 84.Bd -literal -offset indent 85elfctl file 86elfctl -e +noaslr file 87.Ed 88.Pp 89Features may be specified as numerical values: 90.Bd -literal -offset -indent 91elfctl -e =0x0001,0x0004 file 92.Ed 93.Pp 94Features may also be specified as a single combined value: 95.Bd -literal -offset -indent 96elfctl -e =0x5 file 97.Ed 98.Sh SEE ALSO 99.Xr mitigations 7 100.Sh HISTORY 101.Nm 102first appeared in 103.Fx 12.2 . 104.Sh AUTHORS 105.Nm 106was written by 107.An Bora Ozarslan Mt borako.ozarslan@gmail.com 108under sponsorship from the 109.Fx Foundation. 110