linux-stable.git/net/ipv4/fib_semantics.c, branch linux-4.2.y

ipv4: update RTNH_F_LINKDOWN flag on UP event

2015-12-09T19:31:05+00:00

[ Upstream commit c9b3292eeb52c6834e972eb5b8fe38914771ed12 ]

When nexthop is part of multipath route we should clear the
LINKDOWN flag when link goes UP or when first address is added.
This is needed because we always set LINKDOWN flag when DEAD flag
was set but now on UP the nexthop is not dead anymore. Examples when
LINKDOWN bit can be forgotten when no NETDEV_CHANGE is delivered:

- link goes down (LINKDOWN is set), then link goes UP and device
shows carrier OK but LINKDOWN remains set

- last address is deleted (LINKDOWN is set), then address is
added and device shows carrier OK but LINKDOWN remains set

Steps to reproduce:
modprobe dummy
ifconfig dummy0 192.168.168.1 up

here add a multipath route where one nexthop is for dummy0:

ip route add 1.2.3.4 nexthop dummy0 nexthop SOME_OTHER_DEVICE
ifconfig dummy0 down
ifconfig dummy0 up

now ip route shows nexthop that is not dead. Now set the sysctl var:

echo 1 > /proc/sys/net/ipv4/conf/dummy0/ignore_routes_with_linkdown

now ip route will show a dead nexthop because the forgotten
RTNH_F_LINKDOWN is propagated as RTNH_F_DEAD.

Fixes: 8a3d03166f19 ("net: track link-status of ipv4 nexthops")
Signed-off-by: Julian Anastasov 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: fix to not remove local route on link down

2015-12-09T19:31:05+00:00

[ Upstream commit 4f823defdd5b106a5e89745ee8b163c71855de1e ]

When fib_netdev_event calls fib_disable_ip on NETDEV_DOWN event
we should not delete the local routes if the local address
is still present. The confusion comes from the fact that both
fib_netdev_event and fib_inetaddr_event use the NETDEV_DOWN
constant. Fix it by returning back the variable 'force'.

Steps to reproduce:
modprobe dummy
ifconfig dummy0 192.168.168.1 up
ifconfig dummy0 down
ip route list table local | grep dummy | grep host
local 192.168.168.1 dev dummy0  proto kernel  scope host  src 192.168.168.1

Fixes: 8a3d03166f19 ("net: track link-status of ipv4 nexthops")
Signed-off-by: Julian Anastasov 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: consider TOS in fib_select_default

2015-07-25T05:46:11+00:00

fib_select_default considers alternative routes only when
res->fi is for the first alias in res->fa_head. In the
common case this can happen only when the initial lookup
matches the first alias with highest TOS value. This
prevents the alternative routes to require specific TOS.

This patch solves the problem as follows:

- routes that require specific TOS should be returned by
fib_select_default only when TOS matches, as already done
in fib_table_lookup. This rule implies that depending on the
TOS we can have many different lists of alternative gateways
and we have to keep the last used gateway (fa_default) in first
alias for the TOS instead of using single tb_default value.

- as the aliases are ordered by many keys (TOS desc,
fib_priority asc), we restrict the possible results to
routes with matching TOS and lowest metric (fib_priority)
and routes that match any TOS, again with lowest metric.

For example, packet with TOS 8 can not use gw3 (not lowest
metric), gw4 (different TOS) and gw6 (not lowest metric),
all other gateways can be used:

tos 8 via gw1 metric 2 <--- res->fa_head and res->fi
tos 8 via gw2 metric 2
tos 8 via gw3 metric 3
tos 4 via gw4
tos 0 via gw5
tos 0 via gw6 metric 1

Reported-by: Hagen Paul Pfeifer 
Signed-off-by: Julian Anastasov 
Signed-off-by: David S. Miller

ipv4: fib_select_default should match the prefix

2015-07-25T05:46:09+00:00

fib_trie starting from 4.1 can link fib aliases from
different prefixes in same list. Make sure the alternative
gateways are in same table and for same prefix (0) by
checking tb_id and fa_slen.

Fixes: 79e5ad2ceb00 ("fib_trie: Remove leaf_info")
Signed-off-by: Julian Anastasov 
Signed-off-by: David S. Miller

ipv4: fix RCU lockdep warning from linkdown changes

2015-06-28T23:47:12+00:00

The following lockdep splat was seen due to the wrong context for
grabbing in_dev.

===============================
[ INFO: suspicious RCU usage. ]
4.1.0-next-20150626-dbg-00020-g54a6d91-dirty #244 Not tainted
-------------------------------
include/linux/inetdevice.h:205 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
2 locks held by ip/403:
 #0:  (rtnl_mutex){+.+.+.}, at: [] rtnl_lock+0x17/0x19
 #1:  ((inetaddr_chain).rwsem){.+.+.+}, at: [] __blocking_notifier_call_chain+0x35/0x6a

stack backtrace:
CPU: 2 PID: 403 Comm: ip Not tainted 4.1.0-next-20150626-dbg-00020-g54a6d91-dirty #244
 0000000000000001 ffff8800b189b728 ffffffff8150a542 ffffffff8107a8b3
 ffff880037bbea40 ffff8800b189b758 ffffffff8107cb74 ffff8800379dbd00
 ffff8800bec85800 ffff8800bf9e13c0 00000000000000ff ffff8800b189b7d8
Call Trace:
 [] dump_stack+0x4c/0x6e
 [] ? up+0x39/0x3e
 [] lockdep_rcu_suspicious+0xf7/0x100
 [] fib_dump_info+0x227/0x3e2
 [] rtmsg_fib+0xa6/0x116
 [] fib_table_insert+0x316/0x355
 [] fib_magic+0xb7/0xc7
 [] fib_add_ifaddr+0xb1/0x13b
 [] fib_inetaddr_event+0x36/0x90
 [] notifier_call_chain+0x4c/0x71
 [] __blocking_notifier_call_chain+0x4e/0x6a
 [] blocking_notifier_call_chain+0x14/0x16
 [] __inet_insert_ifa+0x1a5/0x1b3
 [] inet_rtm_newaddr+0x350/0x35f
 [] rtnetlink_rcv_msg+0x17b/0x18a
 [] ? trace_hardirqs_on+0xd/0xf
 [] ? netlink_deliver_tap+0x1cb/0x1f7
 [] ? rtnl_newlink+0x72a/0x72a
...

This patch resolves that splat.

Signed-off-by: Andy Gospodarek 
Reported-by: Sergey Senozhatsky 
Signed-off-by: David S. Miller

net: ipv4 sysctl option to ignore routes when nexthop link is down

2015-06-24T09:15:54+00:00

This feature is only enabled with the new per-interface or ipv4 global
sysctls called 'ignore_routes_with_linkdown'.

net.ipv4.conf.all.ignore_routes_with_linkdown = 0
net.ipv4.conf.default.ignore_routes_with_linkdown = 0
net.ipv4.conf.lo.ignore_routes_with_linkdown = 0
...

When the above sysctls are set, will report to userspace that a route is
dead and will no longer resolve to this nexthop when performing a fib
lookup.  This will signal to userspace that the route will not be
selected.  The signalling of a RTNH_F_DEAD is only passed to userspace
if the sysctl is enabled and link is down.  This was done as without it
the netlink listeners would have no idea whether or not a nexthop would
be selected.   The kernel only sets RTNH_F_DEAD internally if the
interface has IFF_UP cleared.

With the new sysctl set, the following behavior can be observed
(interface p8p1 is link-down):

default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1  proto kernel  scope link  src 10.0.5.15
70.0.0.0/24 dev p7p1  proto kernel  scope link  src 70.0.0.1
80.0.0.0/24 dev p8p1  proto kernel  scope link  src 80.0.0.1 dead linkdown
90.0.0.0/24 via 80.0.0.2 dev p8p1  metric 1 dead linkdown
90.0.0.0/24 via 70.0.0.2 dev p7p1  metric 2
90.0.0.1 via 70.0.0.2 dev p7p1  src 70.0.0.1
    cache
local 80.0.0.1 dev lo  src 80.0.0.1
    cache 
80.0.0.2 via 10.0.5.2 dev p9p1  src 10.0.5.15
    cache

While the route does remain in the table (so it can be modified if
needed rather than being wiped away as it would be if IFF_UP was
cleared), the proper next-hop is chosen automatically when the link is
down.  Now interface p8p1 is linked-up:

default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1  proto kernel  scope link  src 10.0.5.15
70.0.0.0/24 dev p7p1  proto kernel  scope link  src 70.0.0.1
80.0.0.0/24 dev p8p1  proto kernel  scope link  src 80.0.0.1
90.0.0.0/24 via 80.0.0.2 dev p8p1  metric 1
90.0.0.0/24 via 70.0.0.2 dev p7p1  metric 2
192.168.56.0/24 dev p2p1  proto kernel  scope link  src 192.168.56.2
90.0.0.1 via 80.0.0.2 dev p8p1  src 80.0.0.1
    cache
local 80.0.0.1 dev lo  src 80.0.0.1
    cache 
80.0.0.2 dev p8p1  src 80.0.0.1
    cache

and the output changes to what one would expect.

If the sysctl is not set, the following output would be expected when
p8p1 is down:

default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1  proto kernel  scope link  src 10.0.5.15
70.0.0.0/24 dev p7p1  proto kernel  scope link  src 70.0.0.1
80.0.0.0/24 dev p8p1  proto kernel  scope link  src 80.0.0.1 linkdown
90.0.0.0/24 via 80.0.0.2 dev p8p1  metric 1 linkdown
90.0.0.0/24 via 70.0.0.2 dev p7p1  metric 2

Since the dead flag does not appear, there should be no expectation that
the kernel would skip using this route due to link being down.

v2: Split kernel changes into 2 patches, this actually makes a
behavioral change if the sysctl is set.  Also took suggestion from Alex
to simplify code by only checking sysctl during fib lookup and
suggestion from Scott to add a per-interface sysctl.

v3: Code clean-ups to make it more readable and efficient as well as a
reverse path check fix.

v4: Drop binary sysctl

v5: Whitespace fixups from Dave

v6: Style changes from Dave and checkpatch suggestions

v7: One more checkpatch fixup

Signed-off-by: Andy Gospodarek 
Signed-off-by: Dinesh Dutt 
Acked-by: Scott Feldman 
Signed-off-by: David S. Miller

net: track link-status of ipv4 nexthops

2015-06-24T09:15:54+00:00

Add a fib flag called RTNH_F_LINKDOWN to any ipv4 nexthops that are
reachable via an interface where carrier is off.  No action is taken,
but additional flags are passed to userspace to indicate carrier status.

This also includes a cleanup to fib_disable_ip to more clearly indicate
what event made the function call to replace the more cryptic force
option previously used.

v2: Split out kernel functionality into 2 patches, this patch simply
sets and clears new nexthop flag RTNH_F_LINKDOWN.

v3: Cleanups suggested by Alex as well as a bug noticed in
fib_sync_down_dev and fib_sync_up when multipath was not enabled.

v5: Whitespace and variable declaration fixups suggested by Dave.

v6: Style fixups noticed by Dave; ran checkpatch to be sure I got them
all.

Signed-off-by: Andy Gospodarek 
Signed-off-by: Dinesh Dutt 
Acked-by: Scott Feldman 
Signed-off-by: David S. Miller

ipv4: remove the unnecessary codes in fib_info_hash_move

2015-05-03T02:17:44+00:00

The whole hlist will be moved, so not need to call hlist_del before
add the hlist_node to other hlist_head.

Signed-off-by: Li RongQing 
Signed-off-by: David S. Miller

ipv4: coding style: comparison for equality with NULL

2015-04-03T16:11:15+00:00

The ipv4 code uses a mixture of coding styles. In some instances check
for NULL pointer is done as x == NULL and sometimes as !x. !x is
preferred according to checkpatch and this patch makes the code
consistent by adopting the latter form.

No changes detected by objdiff.

Signed-off-by: Ian Morris 
Signed-off-by: David S. Miller

netlink: implement nla_get_in_addr and nla_get_in6_addr

2015-03-31T17:58:35+00:00

Those are counterparts to nla_put_in_addr and nla_put_in6_addr.

Signed-off-by: Jiri Benc 
Signed-off-by: David S. Miller