1.\" Copyright (c) 2013 Hudson River Trading LLC 2.\" Written by: John H. Baldwin <jhb@FreeBSD.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.Dd July 12, 2022 27.Dt PROTECT 1 28.Os 29.Sh NAME 30.Nm protect 31.Nd "protect processes from being killed when swap space is exhausted" 32.Sh SYNOPSIS 33.Nm 34.Op Fl i 35.Ar command 36.Nm 37.Op Fl cdi 38.Fl g Ar pgrp 39.Nm 40.Op Fl cdi 41.Fl p Ar pid 42.Sh DESCRIPTION 43The 44.Nm 45command is used to mark processes as protected. 46The kernel does not kill protected processes when swap space is exhausted. 47Note that this protected state is not inherited by child processes by default. 48.Pp 49The options are: 50.Bl -tag -width command 51.It Fl c 52Remove protection from the specified processes. 53.It Fl d 54Apply the operation to all current children of the specified processes. 55.It Fl i 56Apply the operation to all future children of the specified processes. 57.It Fl g Ar pgrp 58Apply the operation to all processes in the specified process group. 59.It Fl p Ar pid 60Apply the operation to the specified process. 61.It Ar command 62Execute 63.Ar command 64as a protected process. 65.El 66.Pp 67Note that only one of the 68.Fl p 69or 70.Fl g 71flags may be specified when adjusting the state of existing processes. 72.Pp 73Daemons can be protected on startup using 74.Ao Ar name Ac Ns Va _oomprotect 75option from 76.Xr rc.conf 5 . 77.Sh EXIT STATUS 78.Ex -std 79.Sh EXAMPLES 80Mark the Xorg server as protected: 81.Pp 82.Dl "pgrep Xorg | xargs protect -p" 83.Pp 84Protect all ssh sessions and their child processes: 85.Pp 86.Dl "pgrep sshd | xargs protect -dip" 87.Pp 88Remove protection from all current and future processes: 89.Pp 90.Dl "protect -cdi -p 1" 91.Pp 92Using 93.Xr ps 1 94to check if the protect flag has been applied to the process: 95.Pp 96.Dl "ps -O flags,flags2 -p 64430" 97.Pp 98.Dl " PID F F2 TT STAT TIME COMMAND" 99.Dl "64430 10104002 00000001 5 S+ 0:00.00 ./main" 100.Dl " ^P ^PI" 101.Pp 102In the above example 103.Nm P 104points at the protected flag and 105.Nm PI 106points at the inheritance flag. 107The process is protected if 108.Nm P 109bit is set to 1. 110All children of this process will also be protected if 111.Nm PI 112bit is set to 1. 113.Sh DIAGNOSTICS 114.Bl -diag 115.It "protect: procctl: Operation not permitted" 116The 117.Nm 118command does not have the required permissions to protect selected processes. 119There are many reasons why this could be the case, e.g.: 120.Bl -dash 121.It 122.Nm 123is not executed by root. 124.It 125.Nm 126is executed inside a 127.Xr jail 8 , 128which is not supported at the moment. 129.El 130.El 131.Sh SEE ALSO 132.Xr ps 1 , 133.Xr procctl 2 , 134.Xr rc.conf 5 135.Sh BUGS 136If you protect a runaway process that allocates all memory the system will 137deadlock. 138