From 7a7043c787b61d6bf02733a04ade1947fc4ded2b Mon Sep 17 00:00:00 2001
From: Attilio Rao <attilio@FreeBSD.org>
Date: Wed, 25 Nov 2009 15:12:24 +0000
Subject: [PATCH] Avoid sshd, cron, syslogd and inetd to be killed under
 high-pressure swap environments. Please note that this can't be done while
 such processes run in jails.

Note: in future it would be interesting to find a way to do that
selectively for any desired proccess (choosen by user himself), probabilly
via a ptrace interface or whatever.

Obtained from:	Sandvine Incorporated
Reviewed by:	emaste, arch@
Sponsored by:	Sandvine Incorporated
MFC:		1 month
---
 crypto/openssh/sshd.c      | 5 +++++
 usr.sbin/cron/cron/cron.c  | 4 ++++
 usr.sbin/inetd/inetd.c     | 4 ++++
 usr.sbin/syslogd/syslogd.c | 4 ++++
 4 files changed, 17 insertions(+)

diff --git a/crypto/openssh/sshd.c b/crypto/openssh/sshd.c
index 249e20f355c5..422f0cb17a7e 100644
--- a/crypto/openssh/sshd.c
+++ b/crypto/openssh/sshd.c
@@ -47,6 +47,7 @@ __RCSID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/ioctl.h>
+#include <sys/mman.h>
 #include <sys/socket.h>
 #ifdef HAVE_SYS_STAT_H
 # include <sys/stat.h>
@@ -1293,6 +1294,10 @@ main(int ac, char **av)
 	/* Initialize configuration options to their default values. */
 	initialize_server_options(&options);
 
+	/* Avoid killing the process in high-pressure swapping environments. */
+	if (madvise(NULL, 0, MADV_PROTECT) != 0)
+		debug("madvise(): %.200s", strerror(errno));
+
 	/* Parse command-line arguments. */
 	while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
 		switch (opt) {
diff --git a/usr.sbin/cron/cron/cron.c b/usr.sbin/cron/cron/cron.c
index 101989c45d21..52cdcc8612a8 100644
--- a/usr.sbin/cron/cron/cron.c
+++ b/usr.sbin/cron/cron/cron.c
@@ -24,6 +24,7 @@ static const char rcsid[] =
 
 
 #include "cron.h"
+#include <sys/mman.h>
 #include <sys/signal.h>
 #if SYS_TIME_H
 # include <sys/time.h>
@@ -134,6 +135,9 @@ main(argc, argv)
 		}
 	}
 
+	if (madvise(NULL, 0, MADV_PROTECT) != 0)
+		log_it("CRON", getpid(), "WARNING", "madvise() failed");
+
 	pidfile_write(pfh);
 	database.head = NULL;
 	database.tail = NULL;
diff --git a/usr.sbin/inetd/inetd.c b/usr.sbin/inetd/inetd.c
index 6bcbac61badc..e8d34f462835 100644
--- a/usr.sbin/inetd/inetd.c
+++ b/usr.sbin/inetd/inetd.c
@@ -110,6 +110,7 @@ __FBSDID("$FreeBSD$");
  */
 #include <sys/param.h>
 #include <sys/ioctl.h>
+#include <sys/mman.h>
 #include <sys/wait.h>
 #include <sys/time.h>
 #include <sys/resource.h>
@@ -497,6 +498,9 @@ main(int argc, char **argv)
 		}
 	}
 
+	if (madvise(NULL, 0, MADV_PROTECT) != 0)
+		syslog(LOG_WARNING, "madvise() failed: %s", strerror(errno));
+
 	for (i = 0; i < PERIPSIZE; ++i)
 		LIST_INIT(&proctable[i]);
 
diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c
index 3e628a24ed2e..5cb0af9186c3 100644
--- a/usr.sbin/syslogd/syslogd.c
+++ b/usr.sbin/syslogd/syslogd.c
@@ -77,6 +77,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/ioctl.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <sys/socket.h>
@@ -352,6 +353,9 @@ main(int argc, char *argv[])
 	pid_t ppid = 1, spid;
 	socklen_t len;
 
+	if (madvise(NULL, 0, MADV_PROTECT) != 0)
+		dprintf("madvise() failed: %s\n", strerror(errno));
+
 	bindhostname = NULL;
 	while ((ch = getopt(argc, argv, "468Aa:b:cCdf:kl:m:nop:P:sS:Tuv"))
 	    != -1)