linux-stable.git/drivers/net/tun.c, branch v5.15.78 Linux kernel stable tree net: tun: fix bugs for oversize packet when napi frags enabled 2022-11-10T17:15:28+00:00 Ziyang Xuan william.xuanziyang@huawei.com 2022-10-29T09:41:01+00:00 dcc79cf735b8ec4bedaa82c53bed8c62721c042b [ Upstream commit 363a5328f4b0517e59572118ccfb7c626d81dca9 ] Recently, we got two syzkaller problems because of oversize packet when napi frags enabled. One of the problems is because the first seg size of the iov_iter from user space is very big, it is 2147479538 which is bigger than the threshold value for bail out early in __alloc_pages(). And skb->pfmemalloc is true, __kmalloc_reserve() would use pfmemalloc reserves without __GFP_NOWARN flag. Thus we got a warning as following: ======================================================== WARNING: CPU: 1 PID: 17965 at mm/page_alloc.c:5295 __alloc_pages+0x1308/0x16c4 mm/page_alloc.c:5295 ... Call trace: __alloc_pages+0x1308/0x16c4 mm/page_alloc.c:5295 __alloc_pages_node include/linux/gfp.h:550 [inline] alloc_pages_node include/linux/gfp.h:564 [inline] kmalloc_large_node+0x94/0x350 mm/slub.c:4038 __kmalloc_node_track_caller+0x620/0x8e4 mm/slub.c:4545 __kmalloc_reserve.constprop.0+0x1e4/0x2b0 net/core/skbuff.c:151 pskb_expand_head+0x130/0x8b0 net/core/skbuff.c:1654 __skb_grow include/linux/skbuff.h:2779 [inline] tun_napi_alloc_frags+0x144/0x610 drivers/net/tun.c:1477 tun_get_user+0x31c/0x2010 drivers/net/tun.c:1835 tun_chr_write_iter+0x98/0x100 drivers/net/tun.c:2036 The other problem is because odd IPv6 packets without NEXTHDR_NONE extension header and have big packet length, it is 2127925 which is bigger than ETH_MAX_MTU(65535). After ipv6_gso_pull_exthdrs() in ipv6_gro_receive(), network_header offset and transport_header offset are all bigger than U16_MAX. That would trigger skb->network_header and skb->transport_header overflow error, because they are all '__u16' type. Eventually, it would affect the value for __skb_push(skb, value), and make it be a big value. After __skb_push() in ipv6_gro_receive(), skb->data would less than skb->head, an out of bounds memory bug occurred. That would trigger the problem as following: ================================================================== BUG: KASAN: use-after-free in eth_type_trans+0x100/0x260 ... Call trace: dump_backtrace+0xd8/0x130 show_stack+0x1c/0x50 dump_stack_lvl+0x64/0x7c print_address_description.constprop.0+0xbc/0x2e8 print_report+0x100/0x1e4 kasan_report+0x80/0x120 __asan_load8+0x78/0xa0 eth_type_trans+0x100/0x260 napi_gro_frags+0x164/0x550 tun_get_user+0xda4/0x1270 tun_chr_write_iter+0x74/0x130 do_iter_readv_writev+0x130/0x1ec do_iter_write+0xbc/0x1e0 vfs_writev+0x13c/0x26c To fix the problems, restrict the packet size less than (ETH_MAX_MTU - NET_SKB_PAD - NET_IP_ALIGN) which has considered reserved skb space in napi_alloc_skb() because transport_header is an offset from skb->head. Add len check in tun_napi_alloc_frags() simply. Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver") Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20221029094101.1653855-1-william.xuanziyang@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 363a5328f4b0517e59572118ccfb7c626d81dca9 ]

Recently, we got two syzkaller problems because of oversize packet
when napi frags enabled.

One of the problems is because the first seg size of the iov_iter
from user space is very big, it is 2147479538 which is bigger than
the threshold value for bail out early in __alloc_pages(). And
skb->pfmemalloc is true, __kmalloc_reserve() would use pfmemalloc
reserves without __GFP_NOWARN flag. Thus we got a warning as following:

========================================================
WARNING: CPU: 1 PID: 17965 at mm/page_alloc.c:5295 __alloc_pages+0x1308/0x16c4 mm/page_alloc.c:5295
...
Call trace:
 __alloc_pages+0x1308/0x16c4 mm/page_alloc.c:5295
 __alloc_pages_node include/linux/gfp.h:550 [inline]
 alloc_pages_node include/linux/gfp.h:564 [inline]
 kmalloc_large_node+0x94/0x350 mm/slub.c:4038
 __kmalloc_node_track_caller+0x620/0x8e4 mm/slub.c:4545
 __kmalloc_reserve.constprop.0+0x1e4/0x2b0 net/core/skbuff.c:151
 pskb_expand_head+0x130/0x8b0 net/core/skbuff.c:1654
 __skb_grow include/linux/skbuff.h:2779 [inline]
 tun_napi_alloc_frags+0x144/0x610 drivers/net/tun.c:1477
 tun_get_user+0x31c/0x2010 drivers/net/tun.c:1835
 tun_chr_write_iter+0x98/0x100 drivers/net/tun.c:2036

The other problem is because odd IPv6 packets without NEXTHDR_NONE
extension header and have big packet length, it is 2127925 which is
bigger than ETH_MAX_MTU(65535). After ipv6_gso_pull_exthdrs() in
ipv6_gro_receive(), network_header offset and transport_header offset
are all bigger than U16_MAX. That would trigger skb->network_header
and skb->transport_header overflow error, because they are all '__u16'
type. Eventually, it would affect the value for __skb_push(skb, value),
and make it be a big value. After __skb_push() in ipv6_gro_receive(),
skb->data would less than skb->head, an out of bounds memory bug occurred.
That would trigger the problem as following:

==================================================================
BUG: KASAN: use-after-free in eth_type_trans+0x100/0x260
...
Call trace:
 dump_backtrace+0xd8/0x130
 show_stack+0x1c/0x50
 dump_stack_lvl+0x64/0x7c
 print_address_description.constprop.0+0xbc/0x2e8
 print_report+0x100/0x1e4
 kasan_report+0x80/0x120
 __asan_load8+0x78/0xa0
 eth_type_trans+0x100/0x260
 napi_gro_frags+0x164/0x550
 tun_get_user+0xda4/0x1270
 tun_chr_write_iter+0x74/0x130
 do_iter_readv_writev+0x130/0x1ec
 do_iter_write+0xbc/0x1e0
 vfs_writev+0x13c/0x26c

To fix the problems, restrict the packet size less than
(ETH_MAX_MTU - NET_SKB_PAD - NET_IP_ALIGN) which has considered reserved
skb space in napi_alloc_skb() because transport_header is an offset from
skb->head. Add len check in tun_napi_alloc_frags() simply.

Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20221029094101.1653855-1-william.xuanziyang@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: tun: split run_ebpf_filter() and pskb_trim() into different "if statement" 2022-07-29T15:25:11+00:00 Dongli Zhang dongli.zhang@oracle.com 2022-03-04T14:55:06+00:00 d2dba226acb9baed97a714e0f7f81a89b2feb63b [ Upstream commit 45a15d89fbcd280571eba8e5ca309e14ba6afa8f ] No functional change. Just to split the if statement into different conditions to use kfree_skb_reason() to trace the reason later. Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joe Jin <joe.jin@oracle.com> Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 45a15d89fbcd280571eba8e5ca309e14ba6afa8f ]

No functional change.

Just to split the if statement into different conditions to use
kfree_skb_reason() to trace the reason later.

Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: tun: avoid disabling NAPI twice 2022-07-07T15:53:29+00:00 Jakub Kicinski kuba@kernel.org 2022-06-29T18:19:10+00:00 c28f955155037586132f8aad573e06a41d260038 commit ff1fa2081d173b01cebe2fbf0a2d0f1cee9ce4b5 upstream. Eric reports that syzbot made short work out of my speculative fix. Indeed when queue gets detached its tfile->tun remains, so we would try to stop NAPI twice with a detach(), close() sequence. Alternative fix would be to move tun_napi_disable() to tun_detach_all() and let the NAPI run after the queue has been detached. Fixes: a8fc8cb5692a ("net: tun: stop NAPI when detaching queues") Reported-by: syzbot <syzkaller@googlegroups.com> Reported-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20220629181911.372047-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ff1fa2081d173b01cebe2fbf0a2d0f1cee9ce4b5 upstream.

Eric reports that syzbot made short work out of my speculative
fix. Indeed when queue gets detached its tfile->tun remains,
so we would try to stop NAPI twice with a detach(), close()
sequence.

Alternative fix would be to move tun_napi_disable() to
tun_detach_all() and let the NAPI run after the queue
has been detached.

Fixes: a8fc8cb5692a ("net: tun: stop NAPI when detaching queues")
Reported-by: syzbot <syzkaller@googlegroups.com>
Reported-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220629181911.372047-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: tun: stop NAPI when detaching queues 2022-07-07T15:53:25+00:00 Jakub Kicinski kuba@kernel.org 2022-06-23T04:21:05+00:00 92e4f3ee5831e025a5bcd81782b1d41b27a90c52 commit a8fc8cb5692aebb9c6f7afd4265366d25dcd1d01 upstream. While looking at a syzbot report I noticed the NAPI only gets disabled before it's deleted. I think that user can detach the queue before destroying the device and the NAPI will never be stopped. Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver") Acked-by: Petar Penkov <ppenkov@aviatrix.com> Link: https://lore.kernel.org/r/20220623042105.2274812-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a8fc8cb5692aebb9c6f7afd4265366d25dcd1d01 upstream.

While looking at a syzbot report I noticed the NAPI only gets
disabled before it's deleted. I think that user can detach
the queue before destroying the device and the NAPI will never
be stopped.

Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver")
Acked-by: Petar Penkov <ppenkov@aviatrix.com>
Link: https://lore.kernel.org/r/20220623042105.2274812-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: tun: unlink NAPI from device on destruction 2022-07-07T15:53:25+00:00 Jakub Kicinski kuba@kernel.org 2022-06-23T04:20:39+00:00 8145f77d38de4f88b8a69e1463f5c09ba189d77c commit 3b9bc84d311104906d2b4995a9a02d7b7ddab2db upstream. Syzbot found a race between tun file and device destruction. NAPIs live in struct tun_file which can get destroyed before the netdev so we have to del them explicitly. The current code is missing deleting the NAPI if the queue was detached first. Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver") Reported-by: syzbot+b75c138e9286ac742647@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/20220623042039.2274708-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3b9bc84d311104906d2b4995a9a02d7b7ddab2db upstream.

Syzbot found a race between tun file and device destruction.
NAPIs live in struct tun_file which can get destroyed before
the netdev so we have to del them explicitly. The current
code is missing deleting the NAPI if the queue was detached
first.

Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver")
Reported-by: syzbot+b75c138e9286ac742647@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20220623042039.2274708-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tuntap: add sanity checks about msg_controllen in sendmsg 2022-04-13T18:59:07+00:00 Harold Huang baymaxhuang@gmail.com 2022-03-03T02:24:40+00:00 bb78c3b11f4d8d8fac4b19b5fd0b1c3b21465cd1 [ Upstream commit 74a335a07a17d131b9263bfdbdcb5e40673ca9ca ] In patch [1], tun_msg_ctl was added to allow pass batched xdp buffers to tun_sendmsg. Although we donot use msg_controllen in this path, we should check msg_controllen to make sure the caller pass a valid msg_ctl. [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe8dd45bb7556246c6b76277b1ba4296c91c2505 Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Suggested-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Harold Huang <baymaxhuang@gmail.com> Acked-by: Jason Wang <jasowang@redhat.com> Link: https://lore.kernel.org/r/20220303022441.383865-1-baymaxhuang@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 74a335a07a17d131b9263bfdbdcb5e40673ca9ca ]

In patch [1], tun_msg_ctl was added to allow pass batched xdp buffers to
tun_sendmsg. Although we donot use msg_controllen in this path, we should
check msg_controllen to make sure the caller pass a valid msg_ctl.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe8dd45bb7556246c6b76277b1ba4296c91c2505

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Harold Huang <baymaxhuang@gmail.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20220303022441.383865-1-baymaxhuang@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tun: avoid double free in tun_free_netdev 2021-12-29T11:29:03+00:00 George Kennedy george.kennedy@oracle.com 2021-12-16T18:25:32+00:00 3cb5ae77799e8ed6ec3fec0b6b4cd07f01650cc5 commit 158b515f703e75e7d68289bf4d98c664e1d632df upstream. Avoid double free in tun_free_netdev() by moving the dev->tstats and tun->security allocs to a new ndo_init routine (tun_net_init()) that will be called by register_netdevice(). ndo_init is paired with the desctructor (tun_free_netdev()), so if there's an error in register_netdevice() the destructor will handle the frees. BUG: KASAN: double-free or invalid-free in selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605 CPU: 0 PID: 25750 Comm: syz-executor416 Not tainted 5.16.0-rc2-syzk #1 Hardware name: Red Hat KVM, BIOS Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x89/0xb5 lib/dump_stack.c:106 print_address_description.constprop.9+0x28/0x160 mm/kasan/report.c:247 kasan_report_invalid_free+0x55/0x80 mm/kasan/report.c:372 ____kasan_slab_free mm/kasan/common.c:346 [inline] __kasan_slab_free+0x107/0x120 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:1723 [inline] slab_free_freelist_hook mm/slub.c:1749 [inline] slab_free mm/slub.c:3513 [inline] kfree+0xac/0x2d0 mm/slub.c:4561 selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605 security_tun_dev_free_security+0x4f/0x90 security/security.c:2342 tun_free_netdev+0xe6/0x150 drivers/net/tun.c:2215 netdev_run_todo+0x4df/0x840 net/core/dev.c:10627 rtnl_unlock+0x13/0x20 net/core/rtnetlink.c:112 __tun_chr_ioctl+0x80c/0x2870 drivers/net/tun.c:3302 tun_chr_ioctl+0x2f/0x40 drivers/net/tun.c:3311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x19d/0x220 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Reported-by: syzkaller <syzkaller@googlegroups.com> Signed-off-by: George Kennedy <george.kennedy@oracle.com> Suggested-by: Jakub Kicinski <kuba@kernel.org> Link: https://lore.kernel.org/r/1639679132-19884-1-git-send-email-george.kennedy@oracle.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 158b515f703e75e7d68289bf4d98c664e1d632df upstream.

Avoid double free in tun_free_netdev() by moving the
dev->tstats and tun->security allocs to a new ndo_init routine
(tun_net_init()) that will be called by register_netdevice().
ndo_init is paired with the desctructor (tun_free_netdev()),
so if there's an error in register_netdevice() the destructor
will handle the frees.

BUG: KASAN: double-free or invalid-free in selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605

CPU: 0 PID: 25750 Comm: syz-executor416 Not tainted 5.16.0-rc2-syzk #1
Hardware name: Red Hat KVM, BIOS
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x89/0xb5 lib/dump_stack.c:106
print_address_description.constprop.9+0x28/0x160 mm/kasan/report.c:247
kasan_report_invalid_free+0x55/0x80 mm/kasan/report.c:372
____kasan_slab_free mm/kasan/common.c:346 [inline]
__kasan_slab_free+0x107/0x120 mm/kasan/common.c:374
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:1723 [inline]
slab_free_freelist_hook mm/slub.c:1749 [inline]
slab_free mm/slub.c:3513 [inline]
kfree+0xac/0x2d0 mm/slub.c:4561
selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605
security_tun_dev_free_security+0x4f/0x90 security/security.c:2342
tun_free_netdev+0xe6/0x150 drivers/net/tun.c:2215
netdev_run_todo+0x4df/0x840 net/core/dev.c:10627
rtnl_unlock+0x13/0x20 net/core/rtnetlink.c:112
__tun_chr_ioctl+0x80c/0x2870 drivers/net/tun.c:3302
tun_chr_ioctl+0x2f/0x40 drivers/net/tun.c:3311
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x19d/0x220 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/1639679132-19884-1-git-send-email-george.kennedy@oracle.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tun: fix bonding active backup with arp monitoring 2021-11-25T08:48:42+00:00 Nicolas Dichtel nicolas.dichtel@6wind.com 2021-11-12T07:56:03+00:00 a705254c71fd35191659ab8c69a50b15894dad0d commit a31d27fbed5d518734cb60956303eb15089a7634 upstream. As stated in the bonding doc, trans_start must be set manually for drivers using NETIF_F_LLTX: Drivers that use NETIF_F_LLTX flag must also update netdev_queue->trans_start. If they do not, then the ARP monitor will immediately fail any slaves using that driver, and those slaves will stay down. Link: https://www.kernel.org/doc/html/v5.15/networking/bonding.html#arp-monitor-operation Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a31d27fbed5d518734cb60956303eb15089a7634 upstream.

As stated in the bonding doc, trans_start must be set manually for drivers
using NETIF_F_LLTX:
 Drivers that use NETIF_F_LLTX flag must also update
 netdev_queue->trans_start. If they do not, then the ARP monitor will
 immediately fail any slaves using that driver, and those slaves will stay
 down.

Link: https://www.kernel.org/doc/html/v5.15/networking/bonding.html#arp-monitor-operation
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ethtool: extend coalesce setting uAPI with CQE mode 2021-08-24T14:38:29+00:00 Yufeng Mo moyufeng@huawei.com 2021-08-20T07:35:18+00:00 f3ccfda1931977b80267ba54070a1aeafa18f6ca In order to support more coalesce parameters through netlink, add two new parameter kernel_coal and extack for .set_coalesce and .get_coalesce, then some extra info can return to user with the netlink API. Signed-off-by: Yufeng Mo <moyufeng@huawei.com> Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
In order to support more coalesce parameters through netlink,
add two new parameter kernel_coal and extack for .set_coalesce
and .get_coalesce, then some extra info can return to user with
the netlink API.

Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tun: use DEVICE_ATTR_RO macro 2021-05-19T19:01:44+00:00 YueHaibing yuehaibing@huawei.com 2021-05-19T02:38:50+00:00 bc6d076daa8c66c79bdceda963fa66273103a276 Use DEVICE_ATTR_RO helper instead of plain DEVICE_ATTR, which makes the code a bit shorter and easier to read. Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Use DEVICE_ATTR_RO helper instead of plain DEVICE_ATTR,
which makes the code a bit shorter and easier to read.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>