linux/drivers/net/loopback.c, branch v3.12.14

net loopback: Set loopback_dev to NULL when freed

2013-09-17T23:05:13Z

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" Acked-by: Eric Dumazet Signed-off-by: David S. Miller

net: loopback: fix a dst refcounting issue

2013-01-27T06:30:35Z

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. [] loopback_xmit+0x64/0x83 [] dev_hard_start_xmit+0x26c/0x35e [] dev_queue_xmit+0x2c4/0x37c [] ? dev_hard_start_xmit+0x35e/0x35e [] ? eth_header+0x28/0xb6 [] neigh_resolve_output+0x176/0x1a7 [] ip_finish_output2+0x297/0x30d [] ? ip_finish_output2+0x137/0x30d [] ip_finish_output+0x63/0x68 [] ip_output+0x61/0x67 [] dst_output+0x17/0x1b [] ip_local_out+0x1e/0x23 [] ip_queue_xmit+0x315/0x353 [] ? ip_send_unicast_reply+0x2cc/0x2cc [] tcp_transmit_skb+0x7ca/0x80b [] tcp_connect+0x53c/0x587 [] ? getnstimeofday+0x44/0x7d [] ? ktime_get_real+0x11/0x3e [] tcp_v4_connect+0x3c2/0x431 [] __inet_stream_connect+0x84/0x287 [] ? inet_stream_connect+0x22/0x49 [] ? _local_bh_enable_ip+0x84/0x9f [] ? local_bh_enable+0xd/0x11 [] ? lock_sock_nested+0x6e/0x79 [] ? inet_stream_connect+0x22/0x49 [] inet_stream_connect+0x33/0x49 [] sys_connect+0x75/0x98 This bug was introduced in linux-2.6.35, in commit 7fee226ad2397b (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 Signed-off-by: Eric Dumazet Tested-by: Ben Greear Signed-off-by: David S. Miller

net: loopback: set default mtu to 64K

2012-09-24T20:23:53Z

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 Signed-off-by: David S. Miller

net: Loopback ifindex is constant now

2012-08-09T23:18:07Z

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 Acked-by: Eric Dumazet Signed-off-by: David S. Miller

net: fix race condition in several drivers when reading stats

2012-07-22T19:12:32Z

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 Signed-off-by: David S. Miller

Remove all #inclusions of asm/system.h

2012-03-28T17:30:03Z

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*.*\n!!' `grep -Irl '^#\s*include\s*' *` Signed-off-by: David Howells

net: remove NETIF_F_NO_CSUM feature bit

2011-11-16T22:43:12Z

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 Signed-off-by: David S. Miller

net: Allow ethtool to set interface in loopback mode.

2011-05-08T22:59:12Z

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 Acked-by: Ben Hutchings Signed-off-by: David S. Miller

ip6_pol_route panic: Do not allow VLAN on loopback

2011-04-18T06:27:16Z

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 Signed-off-by: David S. Miller

loopback: convert to hw_features

2011-02-17T22:16:35Z

This also enables TSOv6, TSO-ECN, and UFO as loopback clearly can handle them. Signed-off-by: Michał Mirosław Signed-off-by: David S. Miller