File _service:tar_scm_kernel_repo:backport-fix-ARP-p... of Package iputils

File _service:tar_scm_kernel_repo:backport-fix-ARP-protocol-field-for-AX.25-and-NETROM.patch of Package iputils

From 4646703f6d8eb46355752ec033945405ca482d4e Mon Sep 17 00:00:00 2001
From: Ralf Baechle <ralf@linux-mips.org>
Date: Tue, 7 Feb 2017 22:10:51 +0100
Subject: [PATCH] arping: Fix ARP protocol field for AX.25 and NETROM

Conflict:NA
Reference:https://github.com/iputils/iputils/commit/4646703f6d8eb46355752ec033945405ca482d4e.patch

AX.25 and NETROM differ from other, more ethernet-like protocols in that
they are not using a DIX protocol number but the AX.25 PID.  The arping code
doesn't handle this special case resulting in invalid ARP packets being sent.

The interface bpq0 is an AX.25-over-ethernet interface.  Without this
fix:

# arping -c 1 -I bpq0 172.20.1.3
 ARPING 172.20.1.3 from 172.20.1.2 bpq0
 Sent 1 probes (1 broadcast(s))
 Received 0 response(s)

With this fix:

# arping -c 1 -I bpq0 172.20.1.3
 ARPING 172.20.1.3 from 172.20.1.2 bpq0
 Unicast reply from 172.20.1.3 [88:98:60:A0:92:40:02]  1.402ms
 Sent 1 probes (1 broadcast(s))
 Received 1 response(s)

Closes: https://github.com/iputils/iputils/pull/360

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
[ pvorel: add new lines for readability ]
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 arping.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/arping.c b/arping.c
index 53fdbb48..5df6d9f0 100644
--- a/arping.c
+++ b/arping.c
@@ -37,6 +37,14 @@
 
 #include "iputils_common.h"
 
+/*
+ * As of July 2021 AX.25 PID values are not currently defined in any
+ * userspace headers.
+ */
+#ifndef AX25_P_IP
+# define AX25_P_IP		0xcc	/* ARPA Internet Protocol     */
+#endif
+
 #ifdef DEFAULT_DEVICE
 # define DEFAULT_DEVICE_STR	DEFAULT_DEVICE
 #else
@@ -248,7 +256,17 @@ static int send_pack(struct run_state *ctl)
 	ah->ar_hrd = htons(ME->sll_hatype);
 	if (ah->ar_hrd == htons(ARPHRD_FDDI))
 		ah->ar_hrd = htons(ARPHRD_ETHER);
-	ah->ar_pro = htons(ETH_P_IP);
+
+	/*
+	 * Exceptions everywhere. AX.25 uses the AX.25 PID value not the
+	 * DIX code for the protocol. Make these device structure fields.
+	 */
+	if (ah->ar_hrd == htons(ARPHRD_AX25) ||
+	    ah->ar_hrd == htons(ARPHRD_NETROM))
+		ah->ar_pro = htons(AX25_P_IP);
+	else
+		ah->ar_pro = htons(ETH_P_IP);
+
 	ah->ar_hln = ME->sll_halen;
 	ah->ar_pln = 4;
 	ah->ar_op  = ctl->advert ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
@@ -341,9 +359,17 @@ static int recv_pack(struct run_state *ctl, unsigned char *buf, ssize_t len,
 	    (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))
 		return 0;
 
-	/* Protocol must be IP. */
-	if (ah->ar_pro != htons(ETH_P_IP))
+	/*
+	 * Protocol must be IP - but exceptions everywhere. AX.25 and NETROM
+	 * use the AX.25 PID value not the DIX code for the protocol.
+	 */
+	if (ah->ar_hrd == htons(ARPHRD_AX25) ||
+	    ah->ar_hrd == htons(ARPHRD_NETROM)) {
+		if (ah->ar_pro != htons(AX25_P_IP))
+			return 0;
+	} else if (ah->ar_pro != htons(ETH_P_IP))
 		return 0;
+
 	if (ah->ar_pln != 4)
 		return 0;
 	if (ah->ar_hln != ((struct sockaddr_ll *)&ctl->me)->sll_halen)