linux.git/net/ipv4, branch v5.4-rc6 Linux kernel source tree inet: stop leaking jiffies on the wire 2019-11-01T21:57:52+00:00 Eric Dumazet edumazet@google.com 2019-11-01T17:32:19+00:00 a904a0693c189691eeee64f6c6b188bd7dc244e9 Historically linux tried to stick to RFC 791, 1122, 2003 for IPv4 ID field generation. RFC 6864 made clear that no matter how hard we try, we can not ensure unicity of IP ID within maximum lifetime for all datagrams with a given source address/destination address/protocol tuple. Linux uses a per socket inet generator (inet_id), initialized at connection startup with a XOR of 'jiffies' and other fields that appear clear on the wire. Thiemo Nagel pointed that this strategy is a privacy concern as this provides 16 bits of entropy to fingerprint devices. Let's switch to a random starting point, this is just as good as far as RFC 6864 is concerned and does not leak anything critical. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Thiemo Nagel <tnagel@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Historically linux tried to stick to RFC 791, 1122, 2003
for IPv4 ID field generation.

RFC 6864 made clear that no matter how hard we try,
we can not ensure unicity of IP ID within maximum
lifetime for all datagrams with a given source
address/destination address/protocol tuple.

Linux uses a per socket inet generator (inet_id), initialized
at connection startup with a XOR of 'jiffies' and other
fields that appear clear on the wire.

Thiemo Nagel pointed that this strategy is a privacy
concern as this provides 16 bits of entropy to fingerprint
devices.

Let's switch to a random starting point, this is just as
good as far as RFC 6864 is concerned and does not leak
anything critical.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Thiemo Nagel <tnagel@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: increase tcp_max_syn_backlog max value 2019-10-31T21:02:01+00:00 Eric Dumazet edumazet@google.com 2019-10-30T17:05:46+00:00 623d0c2db02043e43b698fdd8de1bd398b8e7b37 tcp_max_syn_backlog default value depends on memory size and TCP ehash size. Before this patch, the max value was 2048 [1], which is considered too small nowadays. Increase it to 4096 to match the recent SOMAXCONN change. [1] This is with TCP ehash size being capped to 524288 buckets. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Yue Cao <ycao009@ucr.edu> Signed-off-by: David S. Miller <davem@davemloft.net> 
tcp_max_syn_backlog default value depends on memory size
and TCP ehash size. Before this patch, the max value
was 2048 [1], which is considered too small nowadays.

Increase it to 4096 to match the recent SOMAXCONN change.

[1] This is with TCP ehash size being capped to 524288 buckets.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Yue Cao <ycao009@ucr.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: annotate accesses to sk->sk_incoming_cpu 2019-10-30T20:24:25+00:00 Eric Dumazet edumazet@google.com 2019-10-30T20:00:04+00:00 7170a977743b72cf3eb46ef6ef89885dc7ad3621 This socket field can be read and written by concurrent cpus. Use READ_ONCE() and WRITE_ONCE() annotations to document this, and avoid some compiler 'optimizations'. KCSAN reported : BUG: KCSAN: data-race in tcp_v4_rcv / tcp_v4_rcv write to 0xffff88812220763c of 4 bytes by interrupt on cpu 0: sk_incoming_cpu_update include/net/sock.h:953 [inline] tcp_v4_rcv+0x1b3c/0x1bb0 net/ipv4/tcp_ipv4.c:1934 ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:442 [inline] ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5124 process_backlog+0x1d3/0x420 net/core/dev.c:5955 napi_poll net/core/dev.c:6392 [inline] net_rx_action+0x3ae/0xa90 net/core/dev.c:6460 __do_softirq+0x115/0x33f kernel/softirq.c:292 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1082 do_softirq.part.0+0x6b/0x80 kernel/softirq.c:337 do_softirq kernel/softirq.c:329 [inline] __local_bh_enable_ip+0x76/0x80 kernel/softirq.c:189 read to 0xffff88812220763c of 4 bytes by interrupt on cpu 1: sk_incoming_cpu_update include/net/sock.h:952 [inline] tcp_v4_rcv+0x181a/0x1bb0 net/ipv4/tcp_ipv4.c:1934 ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:442 [inline] ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5124 process_backlog+0x1d3/0x420 net/core/dev.c:5955 napi_poll net/core/dev.c:6392 [inline] net_rx_action+0x3ae/0xa90 net/core/dev.c:6460 __do_softirq+0x115/0x33f kernel/softirq.c:292 run_ksoftirqd+0x46/0x60 kernel/softirq.c:603 smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 16 Comm: ksoftirqd/1 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 <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
This socket field can be read and written by concurrent cpus.

Use READ_ONCE() and WRITE_ONCE() annotations to document this,
and avoid some compiler 'optimizations'.

KCSAN reported :

BUG: KCSAN: data-race in tcp_v4_rcv / tcp_v4_rcv

write to 0xffff88812220763c of 4 bytes by interrupt on cpu 0:
 sk_incoming_cpu_update include/net/sock.h:953 [inline]
 tcp_v4_rcv+0x1b3c/0x1bb0 net/ipv4/tcp_ipv4.c:1934
 ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010
 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5124
 process_backlog+0x1d3/0x420 net/core/dev.c:5955
 napi_poll net/core/dev.c:6392 [inline]
 net_rx_action+0x3ae/0xa90 net/core/dev.c:6460
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1082
 do_softirq.part.0+0x6b/0x80 kernel/softirq.c:337
 do_softirq kernel/softirq.c:329 [inline]
 __local_bh_enable_ip+0x76/0x80 kernel/softirq.c:189

read to 0xffff88812220763c of 4 bytes by interrupt on cpu 1:
 sk_incoming_cpu_update include/net/sock.h:952 [inline]
 tcp_v4_rcv+0x181a/0x1bb0 net/ipv4/tcp_ipv4.c:1934
 ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010
 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5124
 process_backlog+0x1d3/0x420 net/core/dev.c:5955
 napi_poll net/core/dev.c:6392 [inline]
 net_rx_action+0x3ae/0xa90 net/core/dev.c:6460
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
 smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16 Comm: ksoftirqd/1 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 <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
erspan: fix the tun_info options_len check for erspan 2019-10-30T00:36:42+00:00 Xin Long lucien.xin@gmail.com 2019-10-28T15:19:35+00:00 2eb8d6d2910cfe3dc67dc056f26f3dd9c63d47cd The check for !md doens't really work for ip_tunnel_info_opts(info) which only does info + 1. Also to avoid out-of-bounds access on info, it should ensure options_len is not less than erspan_metadata in both erspan_xmit() and ip6erspan_tunnel_xmit(). Fixes: 1a66a836da ("gre: add collect_md mode to ERSPAN tunnel") Signed-off-by: Xin Long <lucien.xin@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The check for !md doens't really work for ip_tunnel_info_opts(info) which
only does info + 1. Also to avoid out-of-bounds access on info, it should
ensure options_len is not less than erspan_metadata in both erspan_xmit()
and ip6erspan_tunnel_xmit().

Fixes: 1a66a836da ("gre: add collect_md mode to ERSPAN tunnel")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
udp: fix data-race in udp_set_dev_scratch() 2019-10-28T20:53:40+00:00 Eric Dumazet edumazet@google.com 2019-10-24T18:43:31+00:00 a793183caa9afae907a0d7ddd2ffd57329369bf5 KCSAN reported a data-race in udp_set_dev_scratch() [1] The issue here is that we must not write over skb fields if skb is shared. A similar issue has been fixed in commit 89c22d8c3b27 ("net: Fix skb csum races when peeking") While we are at it, use a helper only dealing with udp_skb_scratch(skb)->csum_unnecessary, as this allows udp_set_dev_scratch() to be called once and thus inlined. [1] BUG: KCSAN: data-race in udp_set_dev_scratch / udpv6_recvmsg write to 0xffff888120278317 of 1 bytes by task 10411 on cpu 1: udp_set_dev_scratch+0xea/0x200 net/ipv4/udp.c:1308 __first_packet_length+0x147/0x420 net/ipv4/udp.c:1556 first_packet_length+0x68/0x2a0 net/ipv4/udp.c:1579 udp_poll+0xea/0x110 net/ipv4/udp.c:2720 sock_poll+0xed/0x250 net/socket.c:1256 vfs_poll include/linux/poll.h:90 [inline] do_select+0x7d0/0x1020 fs/select.c:534 core_sys_select+0x381/0x550 fs/select.c:677 do_pselect.constprop.0+0x11d/0x160 fs/select.c:759 __do_sys_pselect6 fs/select.c:784 [inline] __se_sys_pselect6 fs/select.c:769 [inline] __x64_sys_pselect6+0x12e/0x170 fs/select.c:769 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 read to 0xffff888120278317 of 1 bytes by task 10413 on cpu 0: udp_skb_csum_unnecessary include/net/udp.h:358 [inline] udpv6_recvmsg+0x43e/0xe90 net/ipv6/udp.c:310 inet6_recvmsg+0xbb/0x240 net/ipv6/af_inet6.c:592 sock_recvmsg_nosec+0x5c/0x70 net/socket.c:871 ___sys_recvmsg+0x1a0/0x3e0 net/socket.c:2480 do_recvmmsg+0x19a/0x5c0 net/socket.c:2601 __sys_recvmmsg+0x1ef/0x200 net/socket.c:2680 __do_sys_recvmmsg net/socket.c:2703 [inline] __se_sys_recvmmsg net/socket.c:2696 [inline] __x64_sys_recvmmsg+0x89/0xb0 net/socket.c:2696 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 10413 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: 2276f58ac589 ("udp: use a separate rx queue for packet reception") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Cc: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
KCSAN reported a data-race in udp_set_dev_scratch() [1]

The issue here is that we must not write over skb fields
if skb is shared. A similar issue has been fixed in commit
89c22d8c3b27 ("net: Fix skb csum races when peeking")

While we are at it, use a helper only dealing with
udp_skb_scratch(skb)->csum_unnecessary, as this allows
udp_set_dev_scratch() to be called once and thus inlined.

[1]
BUG: KCSAN: data-race in udp_set_dev_scratch / udpv6_recvmsg

write to 0xffff888120278317 of 1 bytes by task 10411 on cpu 1:
 udp_set_dev_scratch+0xea/0x200 net/ipv4/udp.c:1308
 __first_packet_length+0x147/0x420 net/ipv4/udp.c:1556
 first_packet_length+0x68/0x2a0 net/ipv4/udp.c:1579
 udp_poll+0xea/0x110 net/ipv4/udp.c:2720
 sock_poll+0xed/0x250 net/socket.c:1256
 vfs_poll include/linux/poll.h:90 [inline]
 do_select+0x7d0/0x1020 fs/select.c:534
 core_sys_select+0x381/0x550 fs/select.c:677
 do_pselect.constprop.0+0x11d/0x160 fs/select.c:759
 __do_sys_pselect6 fs/select.c:784 [inline]
 __se_sys_pselect6 fs/select.c:769 [inline]
 __x64_sys_pselect6+0x12e/0x170 fs/select.c:769
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120278317 of 1 bytes by task 10413 on cpu 0:
 udp_skb_csum_unnecessary include/net/udp.h:358 [inline]
 udpv6_recvmsg+0x43e/0xe90 net/ipv6/udp.c:310
 inet6_recvmsg+0xbb/0x240 net/ipv6/af_inet6.c:592
 sock_recvmsg_nosec+0x5c/0x70 net/socket.c:871
 ___sys_recvmsg+0x1a0/0x3e0 net/socket.c:2480
 do_recvmmsg+0x19a/0x5c0 net/socket.c:2601
 __sys_recvmmsg+0x1ef/0x200 net/socket.c:2680
 __do_sys_recvmmsg net/socket.c:2703 [inline]
 __se_sys_recvmmsg net/socket.c:2696 [inline]
 __x64_sys_recvmmsg+0x89/0xb0 net/socket.c:2696
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10413 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Fixes: 2276f58ac589 ("udp: use a separate rx queue for packet reception")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: use skb_queue_empty_lockless() in busy poll contexts 2019-10-28T20:33:41+00:00 Eric Dumazet edumazet@google.com 2019-10-24T05:44:51+00:00 3f926af3f4d688e2e11e7f8ed04e277a14d4d4a4 Busy polling usually runs without locks. Let's use skb_queue_empty_lockless() instead of skb_queue_empty() Also uses READ_ONCE() in __skb_try_recv_datagram() to address a similar potential problem. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Busy polling usually runs without locks.
Let's use skb_queue_empty_lockless() instead of skb_queue_empty()

Also uses READ_ONCE() in __skb_try_recv_datagram() to address
a similar potential problem.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: use skb_queue_empty_lockless() in poll() handlers 2019-10-28T20:33:41+00:00 Eric Dumazet edumazet@google.com 2019-10-24T05:44:50+00:00 3ef7cf57c72f32f61e97f8fa401bc39ea1f1a5d4 Many poll() handlers are lockless. Using skb_queue_empty_lockless() instead of skb_queue_empty() is more appropriate. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Many poll() handlers are lockless. Using skb_queue_empty_lockless()
instead of skb_queue_empty() is more appropriate.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
udp: use skb_queue_empty_lockless() 2019-10-28T20:33:41+00:00 Eric Dumazet edumazet@google.com 2019-10-24T05:44:49+00:00 137a0dbe3426fd7bcfe3f8117b36a87b3590e4eb syzbot reported a data-race [1]. We should use skb_queue_empty_lockless() to document that we are not ensuring a mutual exclusion and silence KCSAN. [1] BUG: KCSAN: data-race in __skb_recv_udp / __udp_enqueue_schedule_skb write to 0xffff888122474b50 of 8 bytes by interrupt on cpu 0: __skb_insert include/linux/skbuff.h:1852 [inline] __skb_queue_before include/linux/skbuff.h:1958 [inline] __skb_queue_tail include/linux/skbuff.h:1991 [inline] __udp_enqueue_schedule_skb+0x2c1/0x410 net/ipv4/udp.c:1470 __udp_queue_rcv_skb net/ipv4/udp.c:1940 [inline] udp_queue_rcv_one_skb+0x7bd/0xc70 net/ipv4/udp.c:2057 udp_queue_rcv_skb+0xb5/0x400 net/ipv4/udp.c:2074 udp_unicast_rcv_skb.isra.0+0x7e/0x1c0 net/ipv4/udp.c:2233 __udp4_lib_rcv+0xa44/0x17c0 net/ipv4/udp.c:2300 udp_rcv+0x2b/0x40 net/ipv4/udp.c:2470 ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:442 [inline] ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5124 process_backlog+0x1d3/0x420 net/core/dev.c:5955 read to 0xffff888122474b50 of 8 bytes by task 8921 on cpu 1: skb_queue_empty include/linux/skbuff.h:1494 [inline] __skb_recv_udp+0x18d/0x500 net/ipv4/udp.c:1653 udp_recvmsg+0xe1/0xb10 net/ipv4/udp.c:1712 inet_recvmsg+0xbb/0x250 net/ipv4/af_inet.c:838 sock_recvmsg_nosec+0x5c/0x70 net/socket.c:871 ___sys_recvmsg+0x1a0/0x3e0 net/socket.c:2480 do_recvmmsg+0x19a/0x5c0 net/socket.c:2601 __sys_recvmmsg+0x1ef/0x200 net/socket.c:2680 __do_sys_recvmmsg net/socket.c:2703 [inline] __se_sys_recvmmsg net/socket.c:2696 [inline] __x64_sys_recvmmsg+0x89/0xb0 net/socket.c:2696 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 8921 Comm: syz-executor.4 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 <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
syzbot reported a data-race [1].

We should use skb_queue_empty_lockless() to document that we are
not ensuring a mutual exclusion and silence KCSAN.

[1]
BUG: KCSAN: data-race in __skb_recv_udp / __udp_enqueue_schedule_skb

write to 0xffff888122474b50 of 8 bytes by interrupt on cpu 0:
 __skb_insert include/linux/skbuff.h:1852 [inline]
 __skb_queue_before include/linux/skbuff.h:1958 [inline]
 __skb_queue_tail include/linux/skbuff.h:1991 [inline]
 __udp_enqueue_schedule_skb+0x2c1/0x410 net/ipv4/udp.c:1470
 __udp_queue_rcv_skb net/ipv4/udp.c:1940 [inline]
 udp_queue_rcv_one_skb+0x7bd/0xc70 net/ipv4/udp.c:2057
 udp_queue_rcv_skb+0xb5/0x400 net/ipv4/udp.c:2074
 udp_unicast_rcv_skb.isra.0+0x7e/0x1c0 net/ipv4/udp.c:2233
 __udp4_lib_rcv+0xa44/0x17c0 net/ipv4/udp.c:2300
 udp_rcv+0x2b/0x40 net/ipv4/udp.c:2470
 ip_protocol_deliver_rcu+0x4d/0x420 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010
 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5124
 process_backlog+0x1d3/0x420 net/core/dev.c:5955

read to 0xffff888122474b50 of 8 bytes by task 8921 on cpu 1:
 skb_queue_empty include/linux/skbuff.h:1494 [inline]
 __skb_recv_udp+0x18d/0x500 net/ipv4/udp.c:1653
 udp_recvmsg+0xe1/0xb10 net/ipv4/udp.c:1712
 inet_recvmsg+0xbb/0x250 net/ipv4/af_inet.c:838
 sock_recvmsg_nosec+0x5c/0x70 net/socket.c:871
 ___sys_recvmsg+0x1a0/0x3e0 net/socket.c:2480
 do_recvmmsg+0x19a/0x5c0 net/socket.c:2601
 __sys_recvmmsg+0x1ef/0x200 net/socket.c:2680
 __do_sys_recvmmsg net/socket.c:2703 [inline]
 __se_sys_recvmmsg net/socket.c:2696 [inline]
 __x64_sys_recvmmsg+0x89/0xb0 net/socket.c:2696
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8921 Comm: syz-executor.4 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 <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: fix route update on metric change. 2019-10-26T18:25:53+00:00 Paolo Abeni pabeni@redhat.com 2019-10-26T09:53:39+00:00 0b834ba00ab5337e938c727e216e1f5249794717 Since commit af4d768ad28c ("net/ipv4: Add support for specifying metric of connected routes"), when updating an IP address with a different metric, the associated connected route is updated, too. Still, the mentioned commit doesn't handle properly some corner cases: $ ip addr add dev eth0 192.168.1.0/24 $ ip addr add dev eth0 192.168.2.1/32 peer 192.168.2.2 $ ip addr add dev eth0 192.168.3.1/24 $ ip addr change dev eth0 192.168.1.0/24 metric 10 $ ip addr change dev eth0 192.168.2.1/32 peer 192.168.2.2 metric 10 $ ip addr change dev eth0 192.168.3.1/24 metric 10 $ ip -4 route 192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.0 192.168.2.2 dev eth0 proto kernel scope link src 192.168.2.1 192.168.3.0/24 dev eth0 proto kernel scope link src 192.168.2.1 metric 10 Only the last route is correctly updated. The problem is the current test in fib_modify_prefix_metric(): if (!(dev->flags & IFF_UP) || ifa->ifa_flags & (IFA_F_SECONDARY | IFA_F_NOPREFIXROUTE) || ipv4_is_zeronet(prefix) || prefix == ifa->ifa_local || ifa->ifa_prefixlen == 32) Which should be the logical 'not' of the pre-existing test in fib_add_ifaddr(): if (!ipv4_is_zeronet(prefix) && !(ifa->ifa_flags & IFA_F_SECONDARY) && (prefix != addr || ifa->ifa_prefixlen < 32)) To properly negate the original expression, we need to change the last logical 'or' to a logical 'and'. Fixes: af4d768ad28c ("net/ipv4: Add support for specifying metric of connected routes") Reported-and-suggested-by: Beniamino Galvani <bgalvani@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Since commit af4d768ad28c ("net/ipv4: Add support for specifying metric
of connected routes"), when updating an IP address with a different metric,
the associated connected route is updated, too.

Still, the mentioned commit doesn't handle properly some corner cases:

$ ip addr add dev eth0 192.168.1.0/24
$ ip addr add dev eth0 192.168.2.1/32 peer 192.168.2.2
$ ip addr add dev eth0 192.168.3.1/24
$ ip addr change dev eth0 192.168.1.0/24 metric 10
$ ip addr change dev eth0 192.168.2.1/32 peer 192.168.2.2 metric 10
$ ip addr change dev eth0 192.168.3.1/24 metric 10
$ ip -4 route
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.0
192.168.2.2 dev eth0 proto kernel scope link src 192.168.2.1
192.168.3.0/24 dev eth0 proto kernel scope link src 192.168.2.1 metric 10

Only the last route is correctly updated.

The problem is the current test in fib_modify_prefix_metric():

	if (!(dev->flags & IFF_UP) ||
	    ifa->ifa_flags & (IFA_F_SECONDARY | IFA_F_NOPREFIXROUTE) ||
	    ipv4_is_zeronet(prefix) ||
	    prefix == ifa->ifa_local || ifa->ifa_prefixlen == 32)

Which should be the logical 'not' of the pre-existing test in
fib_add_ifaddr():

	if (!ipv4_is_zeronet(prefix) && !(ifa->ifa_flags & IFA_F_SECONDARY) &&
	    (prefix != addr || ifa->ifa_prefixlen < 32))

To properly negate the original expression, we need to change the last
logical 'or' to a logical 'and'.

Fixes: af4d768ad28c ("net/ipv4: Add support for specifying metric of connected routes")
Reported-and-suggested-by: Beniamino Galvani <bgalvani@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: fix IPSKB_FRAG_PMTU handling with fragmentation 2019-10-21T17:46:42+00:00 Eric Dumazet edumazet@google.com 2019-10-19T16:26:37+00:00 e7a409c3f46cb0dbc7bfd4f6f9421d53e92614a5 This patch removes the iph field from the state structure, which is not properly initialized. Instead, add a new field to make the "do we want to set DF" be the state bit and move the code to set the DF flag from ip_frag_next(). Joint work with Pablo and Linus. Fixes: 19c3401a917b ("net: ipv4: place control buffer handling away from fragmentation iterators") Reported-by: Patrick Schönthaler <patrick@notvads.ovh> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
This patch removes the iph field from the state structure, which is not
properly initialized. Instead, add a new field to make the "do we want
to set DF" be the state bit and move the code to set the DF flag from
ip_frag_next().

Joint work with Pablo and Linus.

Fixes: 19c3401a917b ("net: ipv4: place control buffer handling away from fragmentation iterators")
Reported-by: Patrick Schönthaler <patrick@notvads.ovh>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>