When IPv6 module gets initialized but hits an error in the middle,
kenel panic with:
KASAN: null-ptr-deref in range [0x0000000000000598-0x000000000000059f]
CPU: 1 PID: 361 Comm: insmod
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:__neigh_ifdown.isra.0+0x24b/0x370
RSP: 0018:ffff888012677908 EFLAGS: 00000202
...
Call Trace:
<TASK>
neigh_table_clear+0x94/0x2d0
ndisc_cleanup+0x27/0x40 [ipv6]
inet6_init+0x21c/0x2cb [ipv6]
do_one_initcall+0xd3/0x4d0
do_init_module+0x1ae/0x670
...
Kernel panic - not syncing: Fatal exception
When ipv6 initialization fails, it will try to cleanup and calls:
neigh_table_clear()
neigh_ifdown(tbl, NULL)
pneigh_queue_purge(&tbl->proxy_queue, dev_net(dev == NULL))
# dev_net(NULL) triggers null-ptr-deref.
Fix it by passing NULL to pneigh_queue_purge() in neigh_ifdown() if dev
is NULL, to make kernel not panic immediately.
Fixes: 66ba215cb5 ("neigh: fix possible DoS due to net iface start/stop loop")
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Link: https://lore.kernel.org/r/20221101121552.21890-1-chenzhongjin@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:
@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)
@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@
- RAND = get_random_u32();
... when != RAND
- RAND %= (E);
+ RAND = prandom_u32_max(E);
// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@
((T)get_random_u32()@p & (LITERAL))
// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@
value = None
if literal.startswith('0x'):
value = int(literal, 16)
elif literal[0] in '123456789':
value = int(literal, 10)
if value is None:
print("I don't know how to handle %s" % (literal))
cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
print("Skipping 0x%x for cleanup elsewhere" % (value))
cocci.include_match(False)
elif value & (value + 1) != 0:
print("Skipping 0x%x because it's not a power of two minus one" % (value))
cocci.include_match(False)
elif literal.startswith('0x'):
coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))
// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@
- (FUNC()@p & (LITERAL))
+ prandom_u32_max(RESULT)
@collapse_ret@
type T;
identifier VAR;
expression E;
@@
{
- T VAR;
- VAR = (E);
- return VAR;
+ return E;
}
@drop_var@
type T;
identifier VAR;
@@
{
- T VAR;
... when != VAR
}
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
It is not allowed to call kfree_skb() from hardware interrupt
context or with interrupts being disabled. So add all skb to
a tmp list, then free them after spin_unlock_irqrestore() at
once.
Fixes: 66ba215cb5 ("neigh: fix possible DoS due to net iface start/stop loop")
Suggested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
DECnet is an obsolete network protocol that receives more attention
from kernel janitors than users. It belongs in computer protocol
history museum not in Linux kernel.
It has been "Orphaned" in kernel since 2010. The iproute2 support
for DECnet was dropped in 5.0 release. The documentation link on
Sourceforge says it is abandoned there as well.
Leave the UAPI alone to keep userspace programs compiling.
This means that there is still an empty neighbour table
for AF_DECNET.
The table of /proc/sys/net entries was updated to match
current directories and reformatted to be alphabetical.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: David Ahern <dsahern@kernel.org>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Right now we have a neigh_param PROXY_QLEN which specifies maximum length
of neigh_table->proxy_queue. But in fact, this limitation doesn't work well
because check condition looks like:
tbl->proxy_queue.qlen > NEIGH_VAR(p, PROXY_QLEN)
The problem is that p (struct neigh_parms) is a per-device thing,
but tbl (struct neigh_table) is a system-wide global thing.
It seems reasonable to make proxy_queue limit per-device based.
v2:
- nothing changed in this patch
v3:
- rebase to net tree
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@kernel.org>
Cc: Yajun Deng <yajun.deng@linux.dev>
Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: kernel@openvz.org
Cc: devel@openvz.org
Suggested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Normal processing of ARP request (usually this is Ethernet broadcast
packet) coming to the host is looking like the following:
* the packet comes to arp_process() call and is passed through routing
procedure
* the request is put into the queue using pneigh_enqueue() if
corresponding ARP record is not local (common case for container
records on the host)
* the request is processed by timer (within 80 jiffies by default) and
ARP reply is sent from the same arp_process() using
NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED condition (flag is set inside
pneigh_enqueue())
And here the problem comes. Linux kernel calls pneigh_queue_purge()
which destroys the whole queue of ARP requests on ANY network interface
start/stop event through __neigh_ifdown().
This is actually not a problem within the original world as network
interface start/stop was accessible to the host 'root' only, which
could do more destructive things. But the world is changed and there
are Linux containers available. Here container 'root' has an access
to this API and could be considered as untrusted user in the hosting
(container's) world.
Thus there is an attack vector to other containers on node when
container's root will endlessly start/stop interfaces. We have observed
similar situation on a real production node when docker container was
doing such activity and thus other containers on the node become not
accessible.
The patch proposed doing very simple thing. It drops only packets from
the same namespace in the pneigh_queue_purge() where network interface
state change is detected. This is enough to prevent the problem for the
whole node preserving original semantics of the code.
v2:
- do del_timer_sync() if queue is empty after pneigh_queue_purge()
v3:
- rebase to net tree
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@kernel.org>
Cc: Yajun Deng <yajun.deng@linux.dev>
Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: kernel@openvz.org
Cc: devel@openvz.org
Investigated-by: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
commit ed6cd6a178 ("net, neigh: Set lower cap for neigh_managed_work rearming")
fixed a case when DELAY_PROBE_TIME is configured to 0, the processing of the
system work queue hog CPU to 100%, and further more we should introduce
a new option used by periodic probe
Signed-off-by: Yuwei Wang <wangyuweihx@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Netdev reference helpers have a dev_ prefix for historic
reasons. Renaming the old helpers would be too much churn
but we can rename the tracking ones which are relatively
recent and should be the default for new code.
Rename:
dev_hold_track() -> netdev_hold()
dev_put_track() -> netdev_put()
dev_replace_track() -> netdev_ref_replace()
Link: https://lore.kernel.org/r/20220608043955.919359-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Yuwei reported that plain reuse of DELAY_PROBE_TIME to rearm work queue
in neigh_managed_work is problematic if user explicitly configures the
DELAY_PROBE_TIME to 0 for a neighbor table. Such misconfig can then hog
CPU to 100% processing the system work queue. Instead, set lower interval
bound to HZ which is totally sufficient. Yuwei is additionally looking
into making the interval separately configurable from DELAY_PROBE_TIME.
Reported-by: Yuwei Wang <wangyuweihx@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/netdev/797c3c53-ce1b-9f60-e253-cda615788f4a@iogearbox.net
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://lore.kernel.org/r/3b8c5aa906c52c3a8c995d1b2e8ccf650ea7c716.1653432794.git.daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Creating a new netdevice allocates at least ~50Kb of memory for various
kernel objects, but only ~5Kb of them are accounted to memcg. As a result,
creating an unlimited number of netdevice inside a memcg-limited container
does not fall within memcg restrictions, consumes a significant part
of the host's memory, can cause global OOM and lead to random kills of
host processes.
The main consumers of non-accounted memory are:
~10Kb 80+ kernfs nodes
~6Kb ipv6_add_dev() allocations
6Kb __register_sysctl_table() allocations
4Kb neigh_sysctl_register() allocations
4Kb __devinet_sysctl_register() allocations
4Kb __addrconf_sysctl_register() allocations
Accounting of these objects allows to increase the share of memcg-related
memory up to 60-70% (~38Kb accounted vs ~54Kb total for dummy netdevice
on typical VM with default Fedora 35 kernel) and this should be enough
to somehow protect the host from misuse inside container.
Other related objects are quite small and may not be taken into account
to minimize the expected performance degradation.
It should be separately mentonied ~300 bytes of percpu allocation
of struct ipstats_mib in snmp6_alloc_dev(), on huge multi-cpu nodes
it can become the main consumer of memory.
This patch does not enables kernfs accounting as it affects
other parts of the kernel and should be discussed separately.
However, even without kernfs, this patch significantly improves the
current situation and allows to take into account more than half
of all netdevice allocations.
Signed-off-by: Vasily Averin <vvs@openvz.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/354a0a5f-9ec3-a25c-3215-304eab2157bc@openvz.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Replace kfree_skb() used in __neigh_event_send() with
kfree_skb_reason(). Following drop reasons are added:
SKB_DROP_REASON_NEIGH_FAILED
SKB_DROP_REASON_NEIGH_QUEUEFULL
SKB_DROP_REASON_NEIGH_DEAD
The first two reasons above should be the hot path that skb drops
in neighbour subsystem.
Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
syzkaller was able to trigger a deadlock for NTF_MANAGED entries [0]:
kworker/0:16/14617 is trying to acquire lock:
ffffffff8d4dd370 (&tbl->lock){++-.}-{2:2}, at: ___neigh_create+0x9e1/0x2990 net/core/neighbour.c:652
[...]
but task is already holding lock:
ffffffff8d4dd370 (&tbl->lock){++-.}-{2:2}, at: neigh_managed_work+0x35/0x250 net/core/neighbour.c:1572
The neighbor entry turned to NUD_FAILED state, where __neigh_event_send()
triggered an immediate probe as per commit cd28ca0a3d ("neigh: reduce
arp latency") via neigh_probe() given table lock was held.
One option to fix this situation is to defer the neigh_probe() back to
the neigh_timer_handler() similarly as pre cd28ca0a3d. For the case
of NTF_MANAGED, this deferral is acceptable given this only happens on
actual failure state and regular / expected state is NUD_VALID with the
entry already present.
The fix adds a parameter to __neigh_event_send() in order to communicate
whether immediate probe is allowed or disallowed. Existing call-sites
of neigh_event_send() default as-is to immediate probe. However, the
neigh_managed_work() disables it via use of neigh_event_send_probe().
[0] <TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_deadlock_bug kernel/locking/lockdep.c:2956 [inline]
check_deadlock kernel/locking/lockdep.c:2999 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5027
lock_acquire kernel/locking/lockdep.c:5639 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
__raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
_raw_write_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:334
___neigh_create+0x9e1/0x2990 net/core/neighbour.c:652
ip6_finish_output2+0x1070/0x14f0 net/ipv6/ip6_output.c:123
__ip6_finish_output net/ipv6/ip6_output.c:191 [inline]
__ip6_finish_output+0x61e/0xe90 net/ipv6/ip6_output.c:170
ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224
dst_output include/net/dst.h:451 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
ndisc_send_skb+0xa99/0x17f0 net/ipv6/ndisc.c:508
ndisc_send_ns+0x3a9/0x840 net/ipv6/ndisc.c:650
ndisc_solicit+0x2cd/0x4f0 net/ipv6/ndisc.c:742
neigh_probe+0xc2/0x110 net/core/neighbour.c:1040
__neigh_event_send+0x37d/0x1570 net/core/neighbour.c:1201
neigh_event_send include/net/neighbour.h:470 [inline]
neigh_managed_work+0x162/0x250 net/core/neighbour.c:1574
process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
worker_thread+0x657/0x1110 kernel/workqueue.c:2454
kthread+0x2e9/0x3a0 kernel/kthread.c:377
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Fixes: 7482e3841d ("net, neigh: Add NTF_MANAGED flag for managed neighbor entries")
Reported-by: syzbot+5239d0e1778a500d477a@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Roopa Prabhu <roopa@nvidia.com>
Tested-by: syzbot+5239d0e1778a500d477a@syzkaller.appspotmail.com
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220201193942.5055-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Remove PDE_DATA() completely and replace it with pde_data().
[akpm@linux-foundation.org: fix naming clash in drivers/nubus/proc.c]
[akpm@linux-foundation.org: now fix it properly]
Link: https://lkml.kernel.org/r/20211124081956.87711-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Inside netns owned by non-init userns, sysctls about ARP/neighbor is
currently not visible and configurable.
For the attributes these sysctls correspond to, any modifications make
effects on the performance of networking(ARP, especilly) only in the
scope of netns, which does not affect other netns.
Actually, some tools via netlink can modify these attribute. iproute2 is
an example. see as follows:
$ unshare -ur -n
$ cat /proc/sys/net/ipv4/neigh/lo/retrans_time
cat: can't open '/proc/sys/net/ipv4/neigh/lo/retrans_time': No such file
or directory
$ ip ntable show dev lo
inet arp_cache
dev lo
refcnt 1 reachable 19494 base_reachable 30000 retrans 1000
gc_stale 60000 delay_probe 5000 queue 101
app_probes 0 ucast_probes 3 mcast_probes 3
anycast_delay 1000 proxy_delay 800 proxy_queue 64 locktime 1000
inet6 ndisc_cache
dev lo
refcnt 1 reachable 42394 base_reachable 30000 retrans 1000
gc_stale 60000 delay_probe 5000 queue 101
app_probes 0 ucast_probes 3 mcast_probes 3
anycast_delay 1000 proxy_delay 800 proxy_queue 64 locktime 0
$ ip ntable change name arp_cache dev <if> retrans 2000
inet arp_cache
dev lo
refcnt 1 reachable 22917 base_reachable 30000 retrans 2000
gc_stale 60000 delay_probe 5000 queue 101
app_probes 0 ucast_probes 3 mcast_probes 3
anycast_delay 1000 proxy_delay 800 proxy_queue 64 locktime 1000
inet6 ndisc_cache
dev lo
refcnt 1 reachable 35524 base_reachable 30000 retrans 1000
gc_stale 60000 delay_probe 5000 queue 101
app_probes 0 ucast_probes 3 mcast_probes 3
anycast_delay 1000 proxy_delay 800 proxy_queue 64 locktime 0
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Acked-by: Joanne Koong <joannekoong@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When IPv6 module gets initialized, but it's hitting an error in inet6_init()
where it then needs to undo all the prior initialization work, it also might
do a call to ndisc_cleanup() which then calls neigh_table_clear(). In there
is a missing timer cancellation of the table's managed_work item.
The kernel test robot explicitly triggered this error path and caused a UAF
crash similar to the below:
[...]
[ 28.833183][ C0] BUG: unable to handle page fault for address: f7a43288
[ 28.833973][ C0] #PF: supervisor write access in kernel mode
[ 28.834660][ C0] #PF: error_code(0x0002) - not-present page
[ 28.835319][ C0] *pde = 06b2c067 *pte = 00000000
[ 28.835853][ C0] Oops: 0002 [#1] PREEMPT
[ 28.836367][ C0] CPU: 0 PID: 303 Comm: sed Not tainted 5.16.0-rc1-00233-g83ff5faa0d3b #7
[ 28.837293][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1 04/01/2014
[ 28.838338][ C0] EIP: __run_timers.constprop.0+0x82/0x440
[...]
[ 28.845607][ C0] Call Trace:
[ 28.845942][ C0] <SOFTIRQ>
[ 28.846333][ C0] ? check_preemption_disabled.isra.0+0x2a/0x80
[ 28.846975][ C0] ? __this_cpu_preempt_check+0x8/0xa
[ 28.847570][ C0] run_timer_softirq+0xd/0x40
[ 28.848050][ C0] __do_softirq+0xf5/0x576
[ 28.848547][ C0] ? __softirqentry_text_start+0x10/0x10
[ 28.849127][ C0] do_softirq_own_stack+0x2b/0x40
[ 28.849749][ C0] </SOFTIRQ>
[ 28.850087][ C0] irq_exit_rcu+0x7d/0xc0
[ 28.850587][ C0] common_interrupt+0x2a/0x40
[ 28.851068][ C0] asm_common_interrupt+0x119/0x120
[...]
Note that IPv6 module cannot be unloaded as per 8ce4406103 ("ipv6: do not
allow ipv6 module to be removed") hence this can only be seen during module
initialization error. Tested with kernel test robot's reproducer.
Fixes: 7482e3841d ("net, neigh: Add NTF_MANAGED flag for managed neighbor entries")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Li Zhijian <zhijianx.li@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The combination of NUD_PERMANENT + NTF_MANAGED is not supported and does
not make sense either given the former indicates a static/fixed neighbor
entry whereas the latter a dynamically resolved one. While it is possible
to transition from one over to the other, we should however reject such
creation attempts.
Fixes: 7482e3841d ("net, neigh: Add NTF_MANAGED flag for managed neighbor entries")
Suggested-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Instead of open-coding a check for invalid bits in NTF_EXT_MASK, we can just
use the NLA_POLICY_MASK() helper instead, and simplify NDA_FLAGS_EXT sanity
check this way.
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Currently, NDA_FLAGS_EXT flags allow a maximum of 24 bits to be used for
extended neighbor flags. These are eventually fed into neigh->flags by
shifting with NTF_EXT_SHIFT as per commit 2c611ad97a ("net, neigh:
Extend neigh->flags to 32 bit to allow for extensions").
If really ever needed in future, the full 32 bits from NDA_FLAGS_EXT can
be used, it would only require to move neigh->flags from u32 to u64 inside
the kernel.
Add a build-time assertion such that when extending the NTF_EXT_MASK with
new bits, we'll trigger an error once we surpass the 24th bit. This assumes
that no bit holes in new NTF_EXT_* flags will slip in from UAPI, but I
think this is reasonable to assume.
Suggested-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Allow a user space control plane to insert entries with a new NTF_EXT_MANAGED
flag. The flag then indicates to the kernel that the neighbor entry should be
periodically probed for keeping the entry in NUD_REACHABLE state iff possible.
The use case for this is targeting XDP or tc BPF load-balancers which use
the bpf_fib_lookup() BPF helper in order to piggyback on neighbor resolution
for their backends. Given they cannot be resolved in fast-path, a control
plane inserts the L3 (without L2) entries manually into the neighbor table
and lets the kernel do the neighbor resolution either on the gateway or on
the backend directly in case the latter resides in the same L2. This avoids
to deal with L2 in the control plane and to rebuild what the kernel already
does best anyway.
NTF_EXT_MANAGED can be combined with NTF_EXT_LEARNED in order to avoid GC
eviction. The kernel then adds NTF_MANAGED flagged entries to a per-neighbor
table which gets triggered by the system work queue to periodically call
neigh_event_send() for performing the resolution. The implementation allows
migration from/to NTF_MANAGED neighbor entries, so that already existing
entries can be converted by the control plane if needed. Potentially, we could
make the interval for periodically calling neigh_event_send() configurable;
right now it's set to DELAY_PROBE_TIME which is also in line with mlxsw which
has similar driver-internal infrastructure c723c735fa ("mlxsw: spectrum_router:
Periodically update the kernel's neigh table"). In future, the latter could
possibly reuse the NTF_MANAGED neighbors as well.
Example:
# ./ip/ip n replace 192.168.178.30 dev enp5s0 managed extern_learn
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a managed extern_learn REACHABLE
[...]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Roopa Prabhu <roopa@nvidia.com>
Link: https://linuxplumbersconf.org/event/11/contributions/953/
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, all bits in struct ndmsg's ndm_flags are used up with the most
recent addition of 435f2e7cc0 ("net: bridge: add support for sticky fdb
entries"). This makes it impossible to extend the neighboring subsystem
with new NTF_* flags:
struct ndmsg {
__u8 ndm_family;
__u8 ndm_pad1;
__u16 ndm_pad2;
__s32 ndm_ifindex;
__u16 ndm_state;
__u8 ndm_flags;
__u8 ndm_type;
};
There are ndm_pad{1,2} attributes which are not used. However, due to
uncareful design, the kernel does not enforce them to be zero upon new
neighbor entry addition, and given they've been around forever, it is
not possible to reuse them today due to risk of breakage. One option to
overcome this limitation is to add a new NDA_FLAGS_EXT attribute for
extended flags.
In struct neighbour, there is a 3 byte hole between protocol and ha_lock,
which allows neigh->flags to be extended from 8 to 32 bits while still
being on the same cacheline as before. This also allows for all future
NTF_* flags being in neigh->flags rather than yet another flags field.
Unknown flags in NDA_FLAGS_EXT will be rejected by the kernel.
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Roopa Prabhu <roopa@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, it is not possible to migrate a neighbor entry between NUD_PERMANENT
state and NTF_USE flag with a dynamic NUD state from a user space control plane.
Similarly, it is not possible to add/remove NTF_EXT_LEARNED flag from an existing
neighbor entry in combination with NTF_USE flag.
This is due to the latter directly calling into neigh_event_send() without any
meta data updates as happening in __neigh_update(). Thus, to enable this use
case, extend the latter with a NEIGH_UPDATE_F_USE flag where we break the
NUD_PERMANENT state in particular so that a latter neigh_event_send() is able
to re-resolve a neighbor entry.
Before fix, NUD_PERMANENT -> NUD_* & NTF_USE:
# ./ip/ip n replace 192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a PERMANENT
[...]
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use extern_learn
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a PERMANENT
[...]
As can be seen, despite the admin-triggered replace, the entry remains in the
NUD_PERMANENT state.
After fix, NUD_PERMANENT -> NUD_* & NTF_USE:
# ./ip/ip n replace 192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a PERMANENT
[...]
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use extern_learn
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a extern_learn REACHABLE
[...]
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a extern_learn STALE
[...]
# ./ip/ip n replace 192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a PERMANENT
[...]
After the fix, the admin-triggered replace switches to a dynamic state from
the NTF_USE flag which triggered a new neighbor resolution. Likewise, we can
transition back from there, if needed, into NUD_PERMANENT.
Similar before/after behavior can be observed for below transitions:
Before fix, NTF_USE -> NTF_USE | NTF_EXT_LEARNED -> NTF_USE:
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a REACHABLE
[...]
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use extern_learn
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a REACHABLE
[...]
After fix, NTF_USE -> NTF_USE | NTF_EXT_LEARNED -> NTF_USE:
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a REACHABLE
[...]
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use extern_learn
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a extern_learn REACHABLE
[...]
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a REACHABLE
[..]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Roopa Prabhu <roopa@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The NTF_EXT_LEARNED neigh flag is usually propagated back to user space
upon dump of the neighbor table. However, when used in combination with
NTF_USE flag this is not the case despite exempting the entry from the
garbage collector. This results in inconsistent state since entries are
typically marked in neigh->flags with NTF_EXT_LEARNED, but here they are
not. Fix it by propagating the creation flag to ___neigh_create().
Before fix:
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use extern_learn
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a REACHABLE
[...]
After fix:
# ./ip/ip n replace 192.168.178.30 dev enp5s0 use extern_learn
# ./ip/ip n
192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a extern_learn REACHABLE
[...]
Fixes: 9ce33e4653 ("neighbour: support for NTF_EXT_LEARNED flag")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Roopa Prabhu <roopa@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently there's support for filtering neighbours/links for interfaces
which have a specific master device (using the IFLA_MASTER/NDA_MASTER
attributes).
This patch adds support for filtering interfaces/neighbours dump for
interfaces that *don't* have a master.
Signed-off-by: Lahav Schlesinger <lschlesinger@drivenets.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20210810090658.2778960-1-lschlesinger@drivenets.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The 'if (dev)' statement already move into dev_{put , hold}, so remove
redundant if statements.
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>
Those files under /proc/net/stat/ don't have vertical alignment, it looks
very difficult. Modify the seq_printf statement, keep vertical alignment.
v2:
- Use seq_puts() and seq_printf() correctly.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>
Trivial conflicts in net/can/isotp.c and
tools/testing/selftests/net/mptcp/mptcp_connect.sh
scaled_ppm_to_ppb() was moved from drivers/ptp/ptp_clock.c
to include/linux/ptp_clock_kernel.h in -next so re-apply
the fix there.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
IFF_POINTOPOINT interfaces use NUD_NOARP entries for IPv6. It's possible to
fill up the neighbour table with enough entries that it will overflow for
valid connections after that.
This behaviour is more prevalent after commit 58956317c8 ("neighbor:
Improve garbage collection") is applied, as it prevents removal from
entries that are not NUD_FAILED, unless they are more than 5s old.
Fixes: 58956317c8 (neighbor: Improve garbage collection)
Reported-by: Kasper Dupont <kasperd@gjkwv.06.feb.2021.kasperd.net>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Integer variable 'bucket' is being initialized however
this value is never read as 'bucket' is assigned zero
in for statement. Remove the redundant assignment.
Cleans up clang warning:
net/core/neighbour.c:3144:6: warning: Value stored to 'bucket' during
its initialization is never read [clang-analyzer-deadcode.DeadStores]
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Following Race Condition was detected:
<CPU A, t0>: Executing: __netif_receive_skb() ->__netif_receive_skb_core()
-> arp_rcv() -> arp_process().arp_process() calls __neigh_lookup() which
takes a reference on neighbour entry 'n'.
Moves further along, arp_process() and calls neigh_update()->
__neigh_update(). Neighbour entry is unlocked just before a call to
neigh_update_gc_list.
This unlocking paves way for another thread that may take a reference on
the same and mark it dead and remove it from gc_list.
<CPU B, t1> - neigh_flush_dev() is under execution and calls
neigh_mark_dead(n) marking the neighbour entry 'n' as dead. Also n will be
removed from gc_list.
Moves further along neigh_flush_dev() and calls
neigh_cleanup_and_release(n), but since reference count increased in t1,
'n' couldn't be destroyed.
<CPU A, t3>- Code hits neigh_update_gc_list, with neighbour entry
set as dead.
<CPU A, t4> - arp_process() finally calls neigh_release(n), destroying
the neighbour entry and we have a destroyed ntry still part of gc_list.
Fixes: eb4e8fac00d1("neighbour: Prevent a dead entry from updating gc_list")
Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
After a short network outage, the dst_entry is timed out and put
in DST_OBSOLETE_DEAD. We are in this code because arp reply comes
from this neighbour after network recovers. There is a potential
race condition that dst_entry is still in DST_OBSOLETE_DEAD.
With that, another neighbour lookup causes more harm than good.
In best case all packets in arp_queue are lost. This is
counterproductive to the original goal of finding a better path
for those packets.
I observed a worst case with 4.x kernel where a dst_entry in
DST_OBSOLETE_DEAD state is associated with loopback net_device.
It leads to an ethernet header with all zero addresses.
A packet with all zero source MAC address is quite deadly with
mac80211, ath9k and 802.11 block ack. It fails
ieee80211_find_sta_by_ifaddr in ath9k (xmit.c). Ath9k flushes tx
queue (ath_tx_complete_aggr). BAW (block ack window) is not
updated. BAW logic is damaged and ath9k transmission is disabled.
Signed-off-by: Tong Zhu <zhutong@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Following race condition was detected:
<CPU A, t0> - neigh_flush_dev() is under execution and calls
neigh_mark_dead(n) marking the neighbour entry 'n' as dead.
<CPU B, t1> - Executing: __netif_receive_skb() ->
__netif_receive_skb_core() -> arp_rcv() -> arp_process().arp_process()
calls __neigh_lookup() which takes a reference on neighbour entry 'n'.
<CPU A, t2> - Moves further along neigh_flush_dev() and calls
neigh_cleanup_and_release(n), but since reference count increased in t2,
'n' couldn't be destroyed.
<CPU B, t3> - Moves further along, arp_process() and calls
neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
the neighbour entry back in gc_list(neigh_mark_dead(), removed it
earlier in t0 from gc_list)
<CPU B, t4> - arp_process() finally calls neigh_release(n), destroying
the neighbour entry.
This leads to 'n' still being part of gc_list, but the actual
neighbour structure has been freed.
The situation can be prevented from happening if we disallow a dead
entry to have any possibility of updating gc_list. This is what the
patch intends to achieve.
Fixes: 9c29a2f55e ("neighbor: Fix locking order for gc_list changes")
Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20210127165453.GA20514@chinagar-linux.qualcomm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
pneigh_enqueue() tries to obtain a random delay by mod
NEIGH_VAR(p, PROXY_DELAY). However, NEIGH_VAR(p, PROXY_DELAY)
migth be zero at that point because someone could write zero
to /proc/sys/net/ipv4/neigh/[device]/proxy_delay after the
callers check it.
This patch uses prandom_u32_max() to get a random delay instead
which avoids potential division by zero.
Signed-off-by: weichenchen <weichen.chen@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 58956317c8 ("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: 58956317c8 ("neighbor: Improve garbage collection")
Signed-off-by: Jeff Dike <jdike@akamai.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20201113015815.31397-1-jdike@akamai.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add an attribute to NDA which will contain all future fdb-specific
attributes in order to avoid polluting the NDA namespace with e.g.
bridge or vxlan specific attributes. The attribute is called
NDA_FDB_EXT_ATTRS and the structure would look like:
[NDA_FDB_EXT_ATTRS] = {
[NFEA_xxx]
}
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
xdp_umem.c had overlapping changes between the 64-bit math fix
for the calculation of npgs and the removal of the zerocopy
memory type which got rid of the chunk_size_nohdr member.
The mlx5 Kconfig conflict is a case where we just take the
net-next copy of the Kconfig entry dependency as it takes on
the ESWITCH dependency by one level of indirection which is
what the 'net' conflicting change is trying to ensure.
Signed-off-by: David S. Miller <davem@davemloft.net>
In commit 19e16d220f ("neigh: support smaller retrans_time settting")
we add more accurate control for ARP and NS. But for ARP I forgot to
update the latest guard in neigh_timer_handler(), then the next
retransmit would be reset to jiffies + HZ/2 if we set the retrans_time
less than 500ms. Fix it by setting the time_before() check to HZ/100.
IPv6 does not have this issue.
Reported-by: Jianwen Ji <jiji@redhat.com>
Fixes: 19e16d220f ("neigh: support smaller retrans_time settting")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Todays vxlan mac fdb entries can point to multiple remote
ips (rdsts) with the sole purpose of replicating
broadcast-multicast and unknown unicast packets to those remote ips.
E-VPN multihoming [1,2,3] requires bridged vxlan traffic to be
load balanced to remote switches (vteps) belonging to the
same multi-homed ethernet segment (E-VPN multihoming is analogous
to multi-homed LAG implementations, but with the inter-switch
peerlink replaced with a vxlan tunnel). In other words it needs
support for mac ecmp. Furthermore, for faster convergence, E-VPN
multihoming needs the ability to update fdb ecmp nexthops independent
of the fdb entries.
New route nexthop API is perfect for this usecase.
This patch extends the vxlan fdb code to take a nexthop id
pointing to an ecmp nexthop group.
Changes include:
- New NDA_NH_ID attribute for fdbs
- Use the newly added fdb nexthop groups
- makes vxlan rdsts and nexthop handling code mutually
exclusive
- since this is a new use-case and the requirement is for ecmp
nexthop groups, the fdb add and update path checks that the
nexthop is really an ecmp nexthop group. This check can be relaxed
in the future, if we want to introduce replication fdb nexthop groups
and allow its use in lieu of current rdst lists.
- fdb update requests with nexthop id's only allowed for existing
fdb's that have nexthop id's
- learning will not override an existing fdb entry with nexthop
group
- I have wrapped the switchdev offload code around the presence of
rdst
[1] E-VPN RFC https://tools.ietf.org/html/rfc7432
[2] E-VPN with vxlan https://tools.ietf.org/html/rfc8365
[3] http://vger.kernel.org/lpc_net2018_talks/scaling_bridge_fdb_database_slidesV3.pdf
Includes a null check fix in vxlan_xmit from Nikolay
v2 - Fixed build issue:
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When a new neighbor entry has been added, event is generated but it does not
include protocol, because its value is assigned after the event notification
routine has run, so move protocol assignment code earlier.
Fixes: df9b0e30d4 ("neighbor: Add protocol attribute")
Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Roman Mashak <mrv@mojatatu.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from userspace in common code. This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.
As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently, we limited the retrans_time to be greater than HZ/2. i.e.
setting retrans_time less than 500ms will not work. This makes the user
unable to achieve a more accurate control for bonding arp fast failover.
Update the sanity check to HZ/100, which is 10ms, to let users have more
ability on the retrans_time control.
v3: sync the behavior with IPv6 and update all the timer handler
v2: use HZ instead of hard code number
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Chen Zhongjin