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author | Simon Kelley <simon@thekelleys.org.uk> | 2006-05-12 14:56:08 -0700 |
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committer | David S. Miller <davem@davemloft.net> | 2006-05-12 14:56:08 -0700 |
commit | bd89efc532fe41f867f848144cc8b42054ddf6f9 (patch) | |
tree | fcf90049cb5a15bf6689cdbc6038c3fe22079009 /net | |
parent | ef34814426862c41c061520d4ac833be5914b5ba (diff) | |
download | linux-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')
-rw-r--r-- | net/atm/clip.c | 2 | ||||
-rw-r--r-- | net/core/neighbour.c | 21 |
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 = { 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); 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) kfree(parms); } - -void neigh_table_init(struct neigh_table *tbl) +void neigh_table_init_no_netlink(struct neigh_table *tbl) { unsigned long now = jiffies; unsigned long phsize; @@ -1383,10 +1382,27 @@ void neigh_table_init(struct neigh_table *tbl) tbl->last_flush = now; tbl->last_rand = now + tbl->parms.reachable_time * 20; +} + +void neigh_table_init(struct neigh_table *tbl) +{ + struct neigh_table *tmp; + + neigh_table_init_no_netlink(tbl); write_lock(&neigh_tbl_lock); + for (tmp = neigh_tables; tmp; tmp = tmp->next) { + if (tmp->family == tbl->family) + break; + } tbl->next = neigh_tables; neigh_tables = tbl; write_unlock(&neigh_tbl_lock); + + if (unlikely(tmp)) { + printk(KERN_ERR "NEIGH: Registering multiple tables for " + "family %d\n", tbl->family); + dump_stack(); + } } int neigh_table_clear(struct neigh_table *tbl) @@ -2657,6 +2673,7 @@ EXPORT_SYMBOL(neigh_rand_reach_time); EXPORT_SYMBOL(neigh_resolve_output); EXPORT_SYMBOL(neigh_table_clear); EXPORT_SYMBOL(neigh_table_init); +EXPORT_SYMBOL(neigh_table_init_no_netlink); EXPORT_SYMBOL(neigh_update); EXPORT_SYMBOL(neigh_update_hhs); EXPORT_SYMBOL(pneigh_enqueue); |