kernel/include/net/neighbour.h, branch linux-5.11.y

net: Exempt multicast addresses from five-second neighbor lifetime

2020-11-13T22:24:39Z

Commit 58956317c8de ("neighbor: Improve garbage collection") guarantees neighbour table entries a five-second lifetime. Processes which make heavy use of multicast can fill the neighour table with multicast addresses in five seconds. At that point, neighbour entries can't be GC-ed because they aren't five seconds old yet, the kernel log starts to fill up with "neighbor table overflow!" messages, and sends start to fail. This patch allows multicast addresses to be thrown out before they've lived out their five seconds. This makes room for non-multicast addresses and makes messages to all addresses more reliable in these circumstances. Fixes: 58956317c8de ("neighbor: Improve garbage collection") Signed-off-by: Jeff Dike Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20201113015815.31397-1-jdike@akamai.com Signed-off-by: Jakub Kicinski

net/sysctl: remove leftover __user annotations on neigh_proc_dointvec*

2020-06-08T14:13:56Z

Remove the leftover __user annotation on the prototypes for neigh_proc_dointvec*. The implementations already got this right, but the headers kept the __user tags around. Fixes: 32927393dc1c ("sysctl: pass kernel pointers to ->proc_handler") Reported-by: build test robot Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro

neighbour: Replace zero-length array with flexible-array member

2020-03-01T05:52:20Z

The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller

neighbour: remove neigh_cleanup() method

2019-12-09T17:48:47Z

neigh_cleanup() has not been used for seven years, and was a wrong design. Messing with shared pointer in bond_neigh_init() without proper memory barriers would at least trigger syzbot complains eventually. It is time to remove this stuff. Fixes: b63b70d87741 ("IPoIB: Use a private hash table for path lookup in xmit path") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2019-11-09T19:04:37Z

One conflict in the BPF samples Makefile, some fixes in 'net' whilst we were converting over to Makefile.target rules in 'net-next'. Signed-off-by: David S. Miller

net: fix data-race in neigh_event_send()

2019-11-08T21:59:53Z

KCSAN reported the following data-race [1] The fix will also prevent the compiler from optimizing out the condition. [1] BUG: KCSAN: data-race in neigh_resolve_output / neigh_resolve_output write to 0xffff8880a41dba78 of 8 bytes by interrupt on cpu 1: neigh_event_send include/net/neighbour.h:443 [inline] neigh_resolve_output+0x78/0x480 net/core/neighbour.c:1474 neigh_output include/net/neighbour.h:511 [inline] ip_finish_output2+0x4af/0xe40 net/ipv4/ip_output.c:228 __ip_finish_output net/ipv4/ip_output.c:308 [inline] __ip_finish_output+0x23a/0x490 net/ipv4/ip_output.c:290 ip_finish_output+0x41/0x160 net/ipv4/ip_output.c:318 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip_output+0xdf/0x210 net/ipv4/ip_output.c:432 dst_output include/net/dst.h:436 [inline] ip_local_out+0x74/0x90 net/ipv4/ip_output.c:125 __ip_queue_xmit+0x3a8/0xa40 net/ipv4/ip_output.c:532 ip_queue_xmit+0x45/0x60 include/net/ip.h:237 __tcp_transmit_skb+0xe81/0x1d60 net/ipv4/tcp_output.c:1169 tcp_transmit_skb net/ipv4/tcp_output.c:1185 [inline] __tcp_retransmit_skb+0x4bd/0x15f0 net/ipv4/tcp_output.c:2976 tcp_retransmit_skb+0x36/0x1a0 net/ipv4/tcp_output.c:2999 tcp_retransmit_timer+0x719/0x16d0 net/ipv4/tcp_timer.c:515 tcp_write_timer_handler+0x42d/0x510 net/ipv4/tcp_timer.c:598 tcp_write_timer+0xd1/0xf0 net/ipv4/tcp_timer.c:618 read to 0xffff8880a41dba78 of 8 bytes by interrupt on cpu 0: neigh_event_send include/net/neighbour.h:442 [inline] neigh_resolve_output+0x57/0x480 net/core/neighbour.c:1474 neigh_output include/net/neighbour.h:511 [inline] ip_finish_output2+0x4af/0xe40 net/ipv4/ip_output.c:228 __ip_finish_output net/ipv4/ip_output.c:308 [inline] __ip_finish_output+0x23a/0x490 net/ipv4/ip_output.c:290 ip_finish_output+0x41/0x160 net/ipv4/ip_output.c:318 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip_output+0xdf/0x210 net/ipv4/ip_output.c:432 dst_output include/net/dst.h:436 [inline] ip_local_out+0x74/0x90 net/ipv4/ip_output.c:125 __ip_queue_xmit+0x3a8/0xa40 net/ipv4/ip_output.c:532 ip_queue_xmit+0x45/0x60 include/net/ip.h:237 __tcp_transmit_skb+0xe81/0x1d60 net/ipv4/tcp_output.c:1169 tcp_transmit_skb net/ipv4/tcp_output.c:1185 [inline] __tcp_retransmit_skb+0x4bd/0x15f0 net/ipv4/tcp_output.c:2976 tcp_retransmit_skb+0x36/0x1a0 net/ipv4/tcp_output.c:2999 tcp_retransmit_timer+0x719/0x16d0 net/ipv4/tcp_timer.c:515 tcp_write_timer_handler+0x42d/0x510 net/ipv4/tcp_timer.c:598 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc3+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller

net: add annotations on hh->hh_len lockless accesses

2019-11-08T04:07:30Z

KCSAN reported a data-race [1] While we can use READ_ONCE() on the read sides, we need to make sure hh->hh_len is written last. [1] BUG: KCSAN: data-race in eth_header_cache / neigh_resolve_output write to 0xffff8880b9dedcb8 of 4 bytes by task 29760 on cpu 0: eth_header_cache+0xa9/0xd0 net/ethernet/eth.c:247 neigh_hh_init net/core/neighbour.c:1463 [inline] neigh_resolve_output net/core/neighbour.c:1480 [inline] neigh_resolve_output+0x415/0x470 net/core/neighbour.c:1470 neigh_output include/net/neighbour.h:511 [inline] ip6_finish_output2+0x7a2/0xec0 net/ipv6/ip6_output.c:116 __ip6_finish_output net/ipv6/ip6_output.c:142 [inline] __ip6_finish_output+0x2d7/0x330 net/ipv6/ip6_output.c:127 ip6_finish_output+0x41/0x160 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip6_output+0xf2/0x280 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:436 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] ndisc_send_skb+0x459/0x5f0 net/ipv6/ndisc.c:505 ndisc_send_ns+0x207/0x430 net/ipv6/ndisc.c:647 rt6_probe_deferred+0x98/0xf0 net/ipv6/route.c:615 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 worker_thread+0xa0/0x800 kernel/workqueue.c:2415 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 read to 0xffff8880b9dedcb8 of 4 bytes by task 29572 on cpu 1: neigh_resolve_output net/core/neighbour.c:1479 [inline] neigh_resolve_output+0x113/0x470 net/core/neighbour.c:1470 neigh_output include/net/neighbour.h:511 [inline] ip6_finish_output2+0x7a2/0xec0 net/ipv6/ip6_output.c:116 __ip6_finish_output net/ipv6/ip6_output.c:142 [inline] __ip6_finish_output+0x2d7/0x330 net/ipv6/ip6_output.c:127 ip6_finish_output+0x41/0x160 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip6_output+0xf2/0x280 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:436 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] ndisc_send_skb+0x459/0x5f0 net/ipv6/ndisc.c:505 ndisc_send_ns+0x207/0x430 net/ipv6/ndisc.c:647 rt6_probe_deferred+0x98/0xf0 net/ipv6/route.c:615 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 worker_thread+0xa0/0x800 kernel/workqueue.c:2415 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 29572 Comm: kworker/1:4 Not tainted 5.4.0-rc6+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events rt6_probe_deferred Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller

net ipv6: Prevent neighbor add if protocol is disabled on device

2019-04-18T06:19:07Z

Disabling IPv6 on an interface removes existing entries but nothing prevents new entries from being manually added. To that end, add a new neigh_table operation, allow_add, that is called on RTM_NEWNEIGH to see if neighbor entries are allowed on a given device. If IPv6 is disabled on the device, allow_add returns false and passes a message back to the user via extack. $ echo 1 > /proc/sys/net/ipv6/conf/eth1/disable_ipv6 $ ip -6 neigh add fe80::4c88:bff:fe21:2704 dev eth1 lladdr de:ad:be:ef:01:01 Error: IPv6 is disabled on this device. Signed-off-by: David Ahern Signed-off-by: David S. Miller

neighbor: Add skip_cache argument to neigh_output

2019-04-08T22:22:41Z

A later patch allows an IPv6 gateway with an IPv4 route. The neighbor entry will exist in the v6 ndisc table and the cached header will contain the ipv6 protocol which is wrong for an IPv4 packet. For an IPv4 packet to use the v6 neighbor entry, neigh_output needs to skip the cached header and just use the output callback for the neigh entry. A future patchset can look at expanding the hh_cache to handle 2 protocols. For now, IPv6 gateways with an IPv4 route will take the extra overhead of generating the header. Signed-off-by: David Ahern Signed-off-by: David S. Miller

neighbour: register rtnl doit handler

2018-12-19T21:37:34Z

this patch registers neigh doit handler. The doit handler returns a neigh entry given dst and dev. This is similar to route and fdb doit (get) handlers. Also moves nda_policy declaration from rtnetlink.c to neighbour.c Signed-off-by: Roopa Prabhu Reviewed-by: David Ahern Signed-off-by: David S. Miller