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authorSimon Kelley <simon@thekelleys.org.uk>2006-05-12 14:56:08 -0700
committerDavid S. Miller <davem@davemloft.net>2006-05-12 14:56:08 -0700
commitbd89efc532fe41f867f848144cc8b42054ddf6f9 (patch)
treefcf90049cb5a15bf6689cdbc6038c3fe22079009 /net/atm
parentef34814426862c41c061520d4ac833be5914b5ba (diff)
downloadlinux-bd89efc532fe41f867f848144cc8b42054ddf6f9.tar.gz
[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/atm')
-rw-r--r--net/atm/clip.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/atm/clip.c b/net/atm/clip.c
index 1a786bfaa41..72d85298266 100644
--- a/net/atm/clip.c
+++ b/net/atm/clip.c
@@ -963,7 +963,7 @@ static struct file_operations arp_seq_fops = {
static int __init atm_clip_init(void)
{
struct proc_dir_entry *p;
- neigh_table_init(&clip_tbl);
+ neigh_table_init_no_netlink(&clip_tbl);
clip_tbl_hook = &clip_tbl;
register_atm_ioctl(&clip_ioctl_ops);