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authorSimon Kelley <simon@thekelleys.org.uk>2006-05-12 17:56:08 -0400
committerDavid S. Miller <davem@davemloft.net>2006-05-12 17:56:08 -0400
commitbd89efc532fe41f867f848144cc8b42054ddf6f9 (patch)
treefcf90049cb5a15bf6689cdbc6038c3fe22079009 /net
parentef34814426862c41c061520d4ac833be5914b5ba (diff)
[NEIGH]: Fix IP-over-ATM and ARP interaction.
The classical IP over ATM code maintains its own IPv4 <-> <ATM stuff> ARP table, using the standard neighbour-table code. The neigh_table_init function adds this neighbour table to a linked list of all neighbor tables which is used by the functions neigh_delete() neigh_add() and neightbl_set(), all called by the netlink code. Once the ATM neighbour table is added to the list, there are two tables with family == AF_INET there, and ARP entries sent via netlink go into the first table with matching family. This is indeterminate and often wrong. To see the bug, on a kernel with CLIP enabled, create a standard IPv4 ARP entry by pinging an unused address on a local subnet. Then attempt to complete that entry by doing ip neigh replace <ip address> lladdr <some mac address> nud reachable Looking at the ARP tables by using ip neigh show will reveal two ARP entries for the same address. One of these can be found in /proc/net/arp, and the other in /proc/net/atm/arp. This patch adds a new function, neigh_table_init_no_netlink() which does everything the neigh_table_init() does, except add the table to the netlink all-arp-tables chain. In addition neigh_table_init() has a check that all tables on the chain have a distinct address family. The init call in clip.c is changed to call neigh_table_init_no_netlink(). Since ATM ARP tables are rather more complicated than can currently be handled by the available rtattrs in the netlink protocol, no functionality is lost by this patch, and non-ATM ARP manipulation via netlink is rescued. A more complete solution would involve a rtattr for ATM ARP entries and some way for the netlink code to give neigh_add and friends more information than just address family with which to find the correct ARP table. [ I've changed the assertion checking in neigh_table_init() to not use BUG_ON() while holding neigh_tbl_lock. Instead we remember that we found an existing tbl with the same family, and after dropping the lock we'll give a diagnostic kernel log message and a stack dump. -DaveM ] Signed-off-by: Simon Kelley <simon@thekelleys.org.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/atm/clip.c2
-rw-r--r--net/core/neighbour.c21
2 files changed, 20 insertions, 3 deletions
diff --git a/net/atm/clip.c b/net/atm/clip.c
index 1a786bfaa416..72d852982664 100644
--- a/net/atm/clip.c
+++ b/net/atm/clip.c
@@ -963,7 +963,7 @@ static struct file_operations arp_seq_fops = {
963static int __init atm_clip_init(void) 963static int __init atm_clip_init(void)
964{ 964{
965 struct proc_dir_entry *p; 965 struct proc_dir_entry *p;
966 neigh_table_init(&clip_tbl); 966 neigh_table_init_no_netlink(&clip_tbl);
967 967
968 clip_tbl_hook = &clip_tbl; 968 clip_tbl_hook = &clip_tbl;
969 register_atm_ioctl(&clip_ioctl_ops); 969 register_atm_ioctl(&clip_ioctl_ops);
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 4cf878efdb49..50a8c73caf97 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1326,8 +1326,7 @@ void neigh_parms_destroy(struct neigh_parms *parms)
1326 kfree(parms); 1326 kfree(parms);
1327} 1327}
1328 1328
1329 1329void neigh_table_init_no_netlink(struct neigh_table *tbl)
1330void neigh_table_init(struct neigh_table *tbl)
1331{ 1330{
1332 unsigned long now = jiffies; 1331 unsigned long now = jiffies;
1333 unsigned long phsize; 1332 unsigned long phsize;
@@ -1383,10 +1382,27 @@ void neigh_table_init(struct neigh_table *tbl)
1383 1382
1384 tbl->last_flush = now; 1383 tbl->last_flush = now;
1385 tbl->last_rand = now + tbl->parms.reachable_time * 20; 1384 tbl->last_rand = now + tbl->parms.reachable_time * 20;
1385}
1386
1387void neigh_table_init(struct neigh_table *tbl)
1388{
1389 struct neigh_table *tmp;
1390
1391 neigh_table_init_no_netlink(tbl);
1386 write_lock(&neigh_tbl_lock); 1392 write_lock(&neigh_tbl_lock);
1393 for (tmp = neigh_tables; tmp; tmp = tmp->next) {
1394 if (tmp->family == tbl->family)
1395 break;
1396 }
1387 tbl->next = neigh_tables; 1397 tbl->next = neigh_tables;
1388 neigh_tables = tbl; 1398 neigh_tables = tbl;
1389 write_unlock(&neigh_tbl_lock); 1399 write_unlock(&neigh_tbl_lock);
1400
1401 if (unlikely(tmp)) {
1402 printk(KERN_ERR "NEIGH: Registering multiple tables for "
1403 "family %d\n", tbl->family);
1404 dump_stack();
1405 }
1390} 1406}
1391 1407
1392int neigh_table_clear(struct neigh_table *tbl) 1408int neigh_table_clear(struct neigh_table *tbl)
@@ -2657,6 +2673,7 @@ EXPORT_SYMBOL(neigh_rand_reach_time);
2657EXPORT_SYMBOL(neigh_resolve_output); 2673EXPORT_SYMBOL(neigh_resolve_output);
2658EXPORT_SYMBOL(neigh_table_clear); 2674EXPORT_SYMBOL(neigh_table_clear);
2659EXPORT_SYMBOL(neigh_table_init); 2675EXPORT_SYMBOL(neigh_table_init);
2676EXPORT_SYMBOL(neigh_table_init_no_netlink);
2660EXPORT_SYMBOL(neigh_update); 2677EXPORT_SYMBOL(neigh_update);
2661EXPORT_SYMBOL(neigh_update_hhs); 2678EXPORT_SYMBOL(neigh_update_hhs);
2662EXPORT_SYMBOL(pneigh_enqueue); 2679EXPORT_SYMBOL(pneigh_enqueue);