It has recently turned up that we have a number of long standing bugs
in the network stack cleanup code with use of the loopback device
after it has been freed that have not turned up because in most cases
the storage allocated to the loopback device is not reused, when those
accesses happen.
Set looback_dev to NULL to trigger oopses instead of silent data corrupt
when we hit this class of bug.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Ben Greear reported crashes in ip_rcv_finish() on a stress
test involving many macvlans.
We tracked the bug to a dst use after free. ip_rcv_finish()
was calling dst->input() and got garbage for dst->input value.
It appears the bug is in loopback driver, lacking
a skb_dst_force() before calling netif_rx().
As a result, a non refcounted dst, normally protected by a
RCU read_lock section, was escaping this section and could
be freed before the packet being processed.
[<ffffffff813a3c4d>] loopback_xmit+0x64/0x83
[<ffffffff81477364>] dev_hard_start_xmit+0x26c/0x35e
[<ffffffff8147771a>] dev_queue_xmit+0x2c4/0x37c
[<ffffffff81477456>] ? dev_hard_start_xmit+0x35e/0x35e
[<ffffffff8148cfa6>] ? eth_header+0x28/0xb6
[<ffffffff81480f09>] neigh_resolve_output+0x176/0x1a7
[<ffffffff814ad835>] ip_finish_output2+0x297/0x30d
[<ffffffff814ad6d5>] ? ip_finish_output2+0x137/0x30d
[<ffffffff814ad90e>] ip_finish_output+0x63/0x68
[<ffffffff814ae412>] ip_output+0x61/0x67
[<ffffffff814ab904>] dst_output+0x17/0x1b
[<ffffffff814adb6d>] ip_local_out+0x1e/0x23
[<ffffffff814ae1c4>] ip_queue_xmit+0x315/0x353
[<ffffffff814adeaf>] ? ip_send_unicast_reply+0x2cc/0x2cc
[<ffffffff814c018f>] tcp_transmit_skb+0x7ca/0x80b
[<ffffffff814c3571>] tcp_connect+0x53c/0x587
[<ffffffff810c2f0c>] ? getnstimeofday+0x44/0x7d
[<ffffffff810c2f56>] ? ktime_get_real+0x11/0x3e
[<ffffffff814c6f9b>] tcp_v4_connect+0x3c2/0x431
[<ffffffff814d6913>] __inet_stream_connect+0x84/0x287
[<ffffffff814d6b38>] ? inet_stream_connect+0x22/0x49
[<ffffffff8108d695>] ? _local_bh_enable_ip+0x84/0x9f
[<ffffffff8108d6c8>] ? local_bh_enable+0xd/0x11
[<ffffffff8146763c>] ? lock_sock_nested+0x6e/0x79
[<ffffffff814d6b38>] ? inet_stream_connect+0x22/0x49
[<ffffffff814d6b49>] inet_stream_connect+0x33/0x49
[<ffffffff814632c6>] sys_connect+0x75/0x98
This bug was introduced in linux-2.6.35, in commit
7fee226ad2 (net: add a noref bit on skb dst)
skb_dst_force() is enforced in dev_queue_xmit() for devices having a
qdisc.
Reported-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
loopback current mtu of 16436 bytes allows no more than 3 MSS TCP
segments per frame, or 48 Kbytes. Changing mtu to 64K allows TCP
stack to build large frames and significantly reduces stack overhead.
Performance boost on bulk TCP transferts can be up to 30 %, partly
because we now have one ACK message for two 64KB segments, and a lower
probability of hitting /proc/sys/net/ipv4/tcp_reordering default limit.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As pointed out, there are places, that access net->loopback_dev->ifindex
and after ifindex generation is made per-net this value becomes constant
equals 1. So go ahead and introduce the LOOPBACK_IFINDEX constant and use
it where appropriate.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix race condition in several network drivers when reading stats on 32bit
UP architectures. These drivers update their stats in a BH context and
therefore should use u64_stats_fetch_begin_bh/u64_stats_fetch_retry_bh
instead of u64_stats_fetch_begin/u64_stats_fetch_retry when reading the
stats.
Signed-off-by: Kevin Groeneveld <kgroeneveld@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove all #inclusions of asm/system.h preparatory to splitting and killing
it. Performed with the following command:
perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *`
Signed-off-by: David Howells <dhowells@redhat.com>
Only distinct use is checking if NETIF_F_NOCACHE_COPY should be
enabled by default. The check heuristics is altered a bit here,
so it hits other people than before. The default shouldn't be
trusted for performance-critical cases anyway.
For all other uses NETIF_F_NO_CSUM is equivalent to NETIF_F_HW_CSUM.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch enables ethtool to set the loopback mode on a given interface.
By configuring the interface in loopback mode in conjunction with a policy
route / rule, a userland application can stress the egress / ingress path
exposing the flows of the change in progress and potentially help developer(s)
understand the impact of those changes without even sending a packet out
on the network.
Following set of commands illustrates one such example -
a) ip -4 addr add 192.168.1.1/24 dev eth1
b) ip -4 rule add from all iif eth1 lookup 250
c) ip -4 route add local 0/0 dev lo proto kernel scope host table 250
d) arp -Ds 192.168.1.100 eth1
e) arp -Ds 192.168.1.200 eth1
f) sysctl -w net.ipv4.ip_nonlocal_bind=1
g) sysctl -w net.ipv4.conf.all.accept_local=1
# Assuming that the machine has 8 cores
h) taskset 000f netserver -L 192.168.1.200
i) taskset 00f0 netperf -t TCP_CRR -L 192.168.1.100 -H 192.168.1.200 -l 30
Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Acked-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Several tests in the ipv6 routing code check IFF_LOOPBACK, and
allowing stacking such as VLAN'ing on top of loopback results in a
netdevice which reports IFF_LOOPBACK but really isn't the loopback
device.
Instead of spamming the ipv6 routing code with even more special tests,
simply disallow VLAN over loopback.
The result of this patch is:
# modprobe 8021q
# vconfig add lo 43
ERROR: trying to add VLAN #43 to IF -:lo:- error: Operation not supported
Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This also enables TSOv6, TSO-ECN, and UFO as loopback clearly can handle them.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>
In various situations, a device provides a packet to our stack and we
drop it before it enters protocol stack :
- softnet backlog full (accounted in /proc/net/softnet_stat)
- bad vlan tag (not accounted)
- unknown/unregistered protocol (not accounted)
We can handle a per-device counter of such dropped frames at core level,
and automatically adds it to the device provided stats (rx_dropped), so
that standard tools can be used (ifconfig, ip link, cat /proc/net/dev)
This is a generalization of commit 8990f468a (net: rx_dropped
accounting), thus reverting it.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
loopback driver uses dev->ml_priv to store its percpu stats pointer.
It uses ugly casts "(void __percpu __force *)" to shut up sparse
complains.
Define an union to better document we use ml_priv in loopback driver and
define a lstats field with appropriate types.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
There is a small possibility that a reader gets incorrect values on 32
bit arches. SNMP applications could catch incorrect counters when a
32bit high part is changed by another stats consumer/provider.
One way to solve this is to add a rtnl_link_stats64 param to all
ndo_get_stats64() methods, and also add such a parameter to
dev_get_stats().
Rule is that we are not allowed to use dev->stats64 as a temporary
storage for 64bit stats, but a caller provided area (usually on stack)
Old drivers (only providing get_stats() method) need no changes.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 6b10de38f0 (loopback: Implement 64bit stats on 32bit arches)
introduced 64bit stats in loopback driver, using a private seqcount and
private helpers.
David suggested to introduce a generic infrastructure, added in (net:
Introduce u64_stats_sync infrastructure)
This patch reimplements loopback 64bit stats using the u64_stats_sync
infrastructure.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Uses a seqcount_t to synchronize stat producer and consumer, for packets
and bytes counter, now u64 types.
(dropped counter being rarely used, stay a native "unsigned long" type)
No noticeable performance impact on x86, as it only adds two increments
per frame. It might be more expensive on arches where smp_wmb() is not
free.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add __percpu sparse annotations to net drivers.
These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors. This patch doesn't affect normal builds.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (34 commits)
m68k: rename global variable vmalloc_end to m68k_vmalloc_end
percpu: add missing per_cpu_ptr_to_phys() definition for UP
percpu: Fix kdump failure if booted with percpu_alloc=page
percpu: make misc percpu symbols unique
percpu: make percpu symbols in ia64 unique
percpu: make percpu symbols in powerpc unique
percpu: make percpu symbols in x86 unique
percpu: make percpu symbols in xen unique
percpu: make percpu symbols in cpufreq unique
percpu: make percpu symbols in oprofile unique
percpu: make percpu symbols in tracer unique
percpu: make percpu symbols under kernel/ and mm/ unique
percpu: remove some sparse warnings
percpu: make alloc_percpu() handle array types
vmalloc: fix use of non-existent percpu variable in put_cpu_var()
this_cpu: Use this_cpu_xx in trace_functions_graph.c
this_cpu: Use this_cpu_xx for ftrace
this_cpu: Use this_cpu_xx in nmi handling
this_cpu: Use this_cpu operations in RCU
this_cpu: Use this_cpu ops for VM statistics
...
Fix up trivial (famous last words) global per-cpu naming conflicts in
arch/x86/kvm/svm.c
mm/slab.c
Defer calling unregister_netdevice_queue to cleanup_net. It's simpler
and it allows the loopback device to land in the same batch as other
network devices.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Generated with the following semantic patch
@@
struct net *n1;
struct net *n2;
@@
- n1 == n2
+ net_eq(n1, n2)
@@
struct net *n1;
struct net *n2;
@@
- n1 != n2
+ !net_eq(n1, n2)
applied over {include,net,drivers/net}.
Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In a couple of cases collapse some extra code like:
int retval = NETDEV_TX_OK;
...
return retval;
into
return NETDEV_TX_OK;
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch is the result of an automatic spatch transformation to convert
all ndo_start_xmit() return values of 0 to NETDEV_TX_OK.
Some occurences are missed by the automatic conversion, those will be
handled in a seperate patch.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
One point of contention in high network loads is the dst_release() performed
when a transmited skb is freed. This is because NIC tx completion calls
dev_kree_skb() long after original call to dev_queue_xmit(skb).
CPU cache is cold and the atomic op in dst_release() stalls. On SMP, this is
quite visible if one CPU is 100% handling softirqs for a network device,
since dst_clone() is done by other cpus, involving cache line ping pongs.
It seems right place to release dst is in dev_hard_start_xmit(), for most
devices but ones that are virtual, and some exceptions.
David Miller suggested to define a new device flag, set in alloc_netdev_mq()
(so that most devices set it at init time), and carefuly unset in devices
which dont want a NULL skb->dst in their ndo_start_xmit().
List of devices that must clear this flag is :
- loopback device, because it calls netif_rx() and quoting Patrick :
"ip_route_input() doesn't accept loopback addresses, so loopback packets
already need to have a dst_entry attached."
- appletalk/ipddp.c : needs skb->dst in its xmit function
- And all devices that call again dev_queue_xmit() from their xmit function
(as some classifiers need skb->dst) : bonding, vlan, macvlan, eql, ifb, hdlc_fr
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We can in some situations drop packets in netif_rx()
loopback driver does not report these (unlikely) drops to its stats,
and incorrectly change packets/bytes counts.
After this patch applied, "ifconfig lo" can reports these drops as in :
# ifconfig lo
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:692562900 errors:3228 dropped:3228 overruns:0 frame:0
TX packets:692562900 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2865674174 (2.6 GiB) TX bytes:2865674174 (2.6 GiB)
I initialy chose to reflect those errors only in tx_dropped/tx_errors, but David
convinced me that it was really RX errors, as loopback_xmit() really starts
a RX process. (calling eth_type_trans() for example, that itself pulls the ethernet header)
These errors are accounted in rx_dropped/rx_errors.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
