net: Fix routing tables with id > 255 for legacy software

ole2pl · davem330 · commit 709772e6e065 · 2008-06-10T15:44:49.000-07:00
Most legacy software do not like tables &gt; 255 as rtm_table is u8
so tb_id is sent &amp;0xff and it is possible to mismatch for example
table 510 with table 254 (main).

This patch introduces RT_TABLE_COMPAT=252 so the code uses it if
tb_id &gt; 255. It makes such old applications happy, new
ones are still able to use RTA_TABLE to get a proper table id.

Signed-off-by: Krzysztof Piotr Oledzki &lt;ole@ans.pl&gt;
Acked-by: Patrick McHardy &lt;kaber@trash.net&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
@@ -246,6 +246,7 @@ enum rt_class_t
 {
 	RT_TABLE_UNSPEC=0,
 /* User defined values */
+	RT_TABLE_COMPAT=252,
 	RT_TABLE_DEFAULT=253,
 	RT_TABLE_MAIN=254,
 	RT_TABLE_LOCAL=255,
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
@@ -960,7 +960,10 @@ int fib_dump_info(struct sk_buff *skb, u32 pid, u32 seq, int event,
 	rtm->rtm_dst_len = dst_len;
 	rtm->rtm_src_len = 0;
 	rtm->rtm_tos = tos;
-	rtm->rtm_table = tb_id;
+	if (tb_id < 256)
+		rtm->rtm_table = tb_id;
+	else
+		rtm->rtm_table = RT_TABLE_COMPAT;
 	NLA_PUT_U32(skb, RTA_TABLE, tb_id);
 	rtm->rtm_type = type;
 	rtm->rtm_flags = fi->fib_flags;

Original file line number	Diff line number	Diff line change
`@@ -246,6 +246,7 @@ enum rt_class_t`
`246`	`246`	`{`
`247`	`247`	`RT_TABLE_UNSPEC=0,`
`248`	`248`	`/* User defined values */`
	`249`	`+ RT_TABLE_COMPAT=252,`
`249`	`250`	`RT_TABLE_DEFAULT=253,`
`250`	`251`	`RT_TABLE_MAIN=254,`
`251`	`252`	`RT_TABLE_LOCAL=255,`