From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 24 Jan 2018 17:05:07 +0100
Subject: Revert "net: sysrq via icmp"
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: 7b24dfd580154797f82046ed54cb85c3ed75b733
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

This reverts commit c3be7bd61d19 ("net: sysrq via icmp").
Carsten suggested to remove it from the queue since probably won't reach
mainline.

Cc: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 Documentation/admin-guide/sysrq.rst |   12 ------------
 include/net/netns/ipv4.h            |    1 -
 net/ipv4/icmp.c                     |   30 ------------------------------
 net/ipv4/sysctl_net_ipv4.c          |    7 -------
 4 files changed, 50 deletions(-)

--- a/Documentation/admin-guide/sysrq.rst
+++ b/Documentation/admin-guide/sysrq.rst
@@ -77,18 +77,6 @@ On all
 
 		echo t > /proc/sysrq-trigger
 
-On all
-        Enable network SysRq by writing a cookie to icmp_echo_sysrq, e.g.::
-
-                echo 0x01020304 >/proc/sys/net/ipv4/icmp_echo_sysrq
-
-        Send an ICMP echo request with this pattern plus the particular
-        SysRq command key. Example::
-
-                ping -c1 -s57 -p0102030468
-
-        will trigger the SysRq-H (help) command.
-
 What are the 'command' keys?
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -78,7 +78,6 @@ struct netns_ipv4 {
 
 	int sysctl_icmp_echo_ignore_all;
 	int sysctl_icmp_echo_ignore_broadcasts;
-	int sysctl_icmp_echo_sysrq;
 	int sysctl_icmp_ignore_bogus_error_responses;
 	int sysctl_icmp_ratelimit;
 	int sysctl_icmp_ratemask;
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -69,7 +69,6 @@
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/fcntl.h>
-#include <linux/sysrq.h>
 #include <linux/socket.h>
 #include <linux/in.h>
 #include <linux/inet.h>
@@ -916,30 +915,6 @@ static bool icmp_redirect(struct sk_buff
 }
 
 /*
- * 32bit and 64bit have different timestamp length, so we check for
- * the cookie at offset 20 and verify it is repeated at offset 50
- */
-#define CO_POS0		20
-#define CO_POS1		50
-#define CO_SIZE		sizeof(int)
-#define ICMP_SYSRQ_SIZE	57
-
-/*
- * We got a ICMP_SYSRQ_SIZE sized ping request. Check for the cookie
- * pattern and if it matches send the next byte as a trigger to sysrq.
- */
-static void icmp_check_sysrq(struct net *net, struct sk_buff *skb)
-{
-	int cookie = htonl(net->ipv4.sysctl_icmp_echo_sysrq);
-	char *p = skb->data;
-
-	if (!memcmp(&cookie, p + CO_POS0, CO_SIZE) &&
-	    !memcmp(&cookie, p + CO_POS1, CO_SIZE) &&
-	    p[CO_POS0 + CO_SIZE] == p[CO_POS1 + CO_SIZE])
-		handle_sysrq(p[CO_POS0 + CO_SIZE]);
-}
-
-/*
  *	Handle ICMP_ECHO ("ping") requests.
  *
  *	RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
@@ -966,11 +941,6 @@ static bool icmp_echo(struct sk_buff *sk
 		icmp_param.data_len	   = skb->len;
 		icmp_param.head_len	   = sizeof(struct icmphdr);
 		icmp_reply(&icmp_param, skb);
-
-		if (skb->len == ICMP_SYSRQ_SIZE &&
-		    net->ipv4.sysctl_icmp_echo_sysrq) {
-			icmp_check_sysrq(net, skb);
-		}
 	}
 	/* should there be an ICMP stat for ignored echos? */
 	return true;
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -767,13 +767,6 @@ static struct ctl_table ipv4_net_table[]
 		.proc_handler	= proc_dointvec
 	},
 	{
-		.procname	= "icmp_echo_sysrq",
-		.data		= &init_net.ipv4.sysctl_icmp_echo_sysrq,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec
-	},
-	{
 		.procname	= "icmp_ignore_bogus_error_responses",
 		.data		= &init_net.ipv4.sysctl_icmp_ignore_bogus_error_responses,
 		.maxlen		= sizeof(int),