linux-stable.git/net/ipv4, branch v5.4.147 Linux kernel stable tree ipv4: fix endianness issue in inet_rtm_getroute_build_skb() 2021-09-15T07:47:38+00:00 Eric Dumazet edumazet@google.com 2021-08-31T02:02:10+00:00 1c9424a765afa20c023d42018d1f5c3d9158a9c3 [ Upstream commit 92548b0ee220e000d81c27ac9a80e0ede895a881 ] The UDP length field should be in network order. This removes the following sparse error: net/ipv4/route.c:3173:27: warning: incorrect type in assignment (different base types) net/ipv4/route.c:3173:27: expected restricted __be16 [usertype] len net/ipv4/route.c:3173:27: got unsigned long Fixes: 404eb77ea766 ("ipv4: support sport, dport and ip_proto in RTM_GETROUTE") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Roopa Prabhu <roopa@nvidia.com> Cc: David Ahern <dsahern@kernel.org> 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 92548b0ee220e000d81c27ac9a80e0ede895a881 ]

The UDP length field should be in network order.
This removes the following sparse error:

net/ipv4/route.c:3173:27: warning: incorrect type in assignment (different base types)
net/ipv4/route.c:3173:27:    expected restricted __be16 [usertype] len
net/ipv4/route.c:3173:27:    got unsigned long

Fixes: 404eb77ea766 ("ipv4: support sport, dport and ip_proto in RTM_GETROUTE")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: David Ahern <dsahern@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
ipv4: make exception cache less predictible 2021-09-15T07:47:37+00:00 Eric Dumazet edumazet@google.com 2021-08-29T22:16:15+00:00 e46e23c289f62ccd8e2230d9ce652072d777ff30 [ Upstream commit 67d6d681e15b578c1725bad8ad079e05d1c48a8e ] Even after commit 6457378fe796 ("ipv4: use siphash instead of Jenkins in fnhe_hashfun()"), an attacker can still use brute force to learn some secrets from a victim linux host. One way to defeat these attacks is to make the max depth of the hash table bucket a random value. Before this patch, each bucket of the hash table used to store exceptions could contain 6 items under attack. After the patch, each bucket would contains a random number of items, between 6 and 10. The attacker can no longer infer secrets. This is slightly increasing memory size used by the hash table, by 50% in average, we do not expect this to be a problem. This patch is more complex than the prior one (IPv6 equivalent), because IPv4 was reusing the oldest entry. Since we need to be able to evict more than one entry per update_or_create_fnhe() call, I had to replace fnhe_oldest() with fnhe_remove_oldest(). Also note that we will queue extra kfree_rcu() calls under stress, which hopefully wont be a too big issue. Fixes: 4895c771c7f0 ("ipv4: Add FIB nexthop exceptions.") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Keyu Man <kman001@ucr.edu> Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: David S. Miller <davem@davemloft.net> Reviewed-by: David Ahern <dsahern@kernel.org> Tested-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 67d6d681e15b578c1725bad8ad079e05d1c48a8e ]

Even after commit 6457378fe796 ("ipv4: use siphash instead of Jenkins in
fnhe_hashfun()"), an attacker can still use brute force to learn
some secrets from a victim linux host.

One way to defeat these attacks is to make the max depth of the hash
table bucket a random value.

Before this patch, each bucket of the hash table used to store exceptions
could contain 6 items under attack.

After the patch, each bucket would contains a random number of items,
between 6 and 10. The attacker can no longer infer secrets.

This is slightly increasing memory size used by the hash table,
by 50% in average, we do not expect this to be a problem.

This patch is more complex than the prior one (IPv6 equivalent),
because IPv4 was reusing the oldest entry.
Since we need to be able to evict more than one entry per
update_or_create_fnhe() call, I had to replace
fnhe_oldest() with fnhe_remove_oldest().

Also note that we will queue extra kfree_rcu() calls under stress,
which hopefully wont be a too big issue.

Fixes: 4895c771c7f0 ("ipv4: Add FIB nexthop exceptions.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Keyu Man <kman001@ucr.edu>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Tested-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: seq_file: Avoid skipping sk during tcp_seek_last_pos 2021-09-15T07:47:32+00:00 Martin KaFai Lau kafai@fb.com 2021-07-01T20:05:41+00:00 37ed461b52e97591fb83449640929a4b2ad4a0c9 [ Upstream commit 525e2f9fd0229eb10cb460a9e6d978257f24804e ] st->bucket stores the current bucket number. st->offset stores the offset within this bucket that is the sk to be seq_show(). Thus, st->offset only makes sense within the same st->bucket. These two variables are an optimization for the common no-lseek case. When resuming the seq_file iteration (i.e. seq_start()), tcp_seek_last_pos() tries to continue from the st->offset at bucket st->bucket. However, it is possible that the bucket pointed by st->bucket has changed and st->offset may end up skipping the whole st->bucket without finding a sk. In this case, tcp_seek_last_pos() currently continues to satisfy the offset condition in the next (and incorrect) bucket. Instead, regardless of the offset value, the first sk of the next bucket should be returned. Thus, "bucket == st->bucket" check is added to tcp_seek_last_pos(). The chance of hitting this is small and the issue is a decade old, so targeting for the next tree. Fixes: a8b690f98baf ("tcp: Fix slowness in read /proc/net/tcp") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210701200541.1033917-1-kafai@fb.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 525e2f9fd0229eb10cb460a9e6d978257f24804e ]

st->bucket stores the current bucket number.
st->offset stores the offset within this bucket that is the sk to be
seq_show().  Thus, st->offset only makes sense within the same
st->bucket.

These two variables are an optimization for the common no-lseek case.
When resuming the seq_file iteration (i.e. seq_start()),
tcp_seek_last_pos() tries to continue from the st->offset
at bucket st->bucket.

However, it is possible that the bucket pointed by st->bucket
has changed and st->offset may end up skipping the whole st->bucket
without finding a sk.  In this case, tcp_seek_last_pos() currently
continues to satisfy the offset condition in the next (and incorrect)
bucket.  Instead, regardless of the offset value, the first sk of the
next bucket should be returned.  Thus, "bucket == st->bucket" check is
added to tcp_seek_last_pos().

The chance of hitting this is small and the issue is a decade old,
so targeting for the next tree.

Fixes: a8b690f98baf ("tcp: Fix slowness in read /proc/net/tcp")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200541.1033917-1-kafai@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
ipv4/icmp: l3mdev: Perform icmp error route lookup on source device routing table (v2) 2021-09-12T06:56:40+00:00 Mathieu Desnoyers mathieu.desnoyers@efficios.com 2020-10-12T14:50:14+00:00 295501c77c4cf0a89cecf6b0301640935c75c949 commit e1e84eb58eb494b77c8389fc6308b5042dcce791 upstream. As per RFC792, ICMP errors should be sent to the source host. However, in configurations with Virtual Routing and Forwarding tables, looking up which routing table to use is currently done by using the destination net_device. commit 9d1a6c4ea43e ("net: icmp_route_lookup should use rt dev to determine L3 domain") changes the interface passed to l3mdev_master_ifindex() and inet_addr_type_dev_table() from skb_in->dev to skb_dst(skb_in)->dev. This effectively uses the destination device rather than the source device for choosing which routing table should be used to lookup where to send the ICMP error. Therefore, if the source and destination interfaces are within separate VRFs, or one in the global routing table and the other in a VRF, looking up the source host in the destination interface's routing table will fail if the destination interface's routing table contains no route to the source host. One observable effect of this issue is that traceroute does not work in the following cases: - Route leaking between global routing table and VRF - Route leaking between VRFs Preferably use the source device routing table when sending ICMP error messages. If no source device is set, fall-back on the destination device routing table. Else, use the main routing table (index 0). [ It has been pointed out that a similar issue may exist with ICMP errors triggered when forwarding between network namespaces. It would be worthwhile to investigate, but is outside of the scope of this investigation. ] [ It has also been pointed out that a similar issue exists with unreachable / fragmentation needed messages, which can be triggered by changing the MTU of eth1 in r1 to 1400 and running: ip netns exec h1 ping -s 1450 -Mdo -c1 172.16.2.2 Some investigation points to raw_icmp_error() and raw_err() as being involved in this last scenario. The focus of this patch is TTL expired ICMP messages, which go through icmp_route_lookup. Investigation of failure modes related to raw_icmp_error() is beyond this investigation's scope. ] Fixes: 9d1a6c4ea43e ("net: icmp_route_lookup should use rt dev to determine L3 domain") Link: https://tools.ietf.org/html/rfc792 Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: David Ahern <dsahern@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e1e84eb58eb494b77c8389fc6308b5042dcce791 upstream.

As per RFC792, ICMP errors should be sent to the source host.

However, in configurations with Virtual Routing and Forwarding tables,
looking up which routing table to use is currently done by using the
destination net_device.

commit 9d1a6c4ea43e ("net: icmp_route_lookup should use rt dev to
determine L3 domain") changes the interface passed to
l3mdev_master_ifindex() and inet_addr_type_dev_table() from skb_in->dev
to skb_dst(skb_in)->dev. This effectively uses the destination device
rather than the source device for choosing which routing table should be
used to lookup where to send the ICMP error.

Therefore, if the source and destination interfaces are within separate
VRFs, or one in the global routing table and the other in a VRF, looking
up the source host in the destination interface's routing table will
fail if the destination interface's routing table contains no route to
the source host.

One observable effect of this issue is that traceroute does not work in
the following cases:

- Route leaking between global routing table and VRF
- Route leaking between VRFs

Preferably use the source device routing table when sending ICMP error
messages. If no source device is set, fall-back on the destination
device routing table. Else, use the main routing table (index 0).

[ It has been pointed out that a similar issue may exist with ICMP
  errors triggered when forwarding between network namespaces. It would
  be worthwhile to investigate, but is outside of the scope of this
  investigation. ]

[ It has also been pointed out that a similar issue exists with
  unreachable / fragmentation needed messages, which can be triggered by
  changing the MTU of eth1 in r1 to 1400 and running:

  ip netns exec h1 ping -s 1450 -Mdo -c1 172.16.2.2

  Some investigation points to raw_icmp_error() and raw_err() as being
  involved in this last scenario. The focus of this patch is TTL expired
  ICMP messages, which go through icmp_route_lookup.
  Investigation of failure modes related to raw_icmp_error() is beyond
  this investigation's scope. ]

Fixes: 9d1a6c4ea43e ("net: icmp_route_lookup should use rt dev to determine L3 domain")
Link: https://tools.ietf.org/html/rfc792
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
igmp: Add ip_mc_list lock in ip_check_mc_rcu 2021-09-12T06:56:40+00:00 Liu Jian liujian56@huawei.com 2021-07-16T04:06:17+00:00 d84708451d9041dff8a81e3718f821f12d2eb6c5 commit 23d2b94043ca8835bd1e67749020e839f396a1c2 upstream. I got below panic when doing fuzz test: Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 4056 Comm: syz-executor.3 Tainted: G B 5.14.0-rc1-00195-gcff5c4254439-dirty #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x7a/0x9b panic+0x2cd/0x5af end_report.cold+0x5a/0x5a kasan_report+0xec/0x110 ip_check_mc_rcu+0x556/0x5d0 __mkroute_output+0x895/0x1740 ip_route_output_key_hash_rcu+0x2d0/0x1050 ip_route_output_key_hash+0x182/0x2e0 ip_route_output_flow+0x28/0x130 udp_sendmsg+0x165d/0x2280 udpv6_sendmsg+0x121e/0x24f0 inet6_sendmsg+0xf7/0x140 sock_sendmsg+0xe9/0x180 ____sys_sendmsg+0x2b8/0x7a0 ___sys_sendmsg+0xf0/0x160 __sys_sendmmsg+0x17e/0x3c0 __x64_sys_sendmmsg+0x9e/0x100 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x462eb9 Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3df5af1c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462eb9 RDX: 0000000000000312 RSI: 0000000020001700 RDI: 0000000000000007 RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3df5af26bc R13: 00000000004c372d R14: 0000000000700b10 R15: 00000000ffffffff It is one use-after-free in ip_check_mc_rcu. In ip_mc_del_src, the ip_sf_list of pmc has been freed under pmc->lock protection. But access to ip_sf_list in ip_check_mc_rcu is not protected by the lock. Signed-off-by: Liu Jian <liujian56@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Lee Jones <lee.jones@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 23d2b94043ca8835bd1e67749020e839f396a1c2 upstream.

I got below panic when doing fuzz test:

Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 4056 Comm: syz-executor.3 Tainted: G    B             5.14.0-rc1-00195-gcff5c4254439-dirty #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack_lvl+0x7a/0x9b
panic+0x2cd/0x5af
end_report.cold+0x5a/0x5a
kasan_report+0xec/0x110
ip_check_mc_rcu+0x556/0x5d0
__mkroute_output+0x895/0x1740
ip_route_output_key_hash_rcu+0x2d0/0x1050
ip_route_output_key_hash+0x182/0x2e0
ip_route_output_flow+0x28/0x130
udp_sendmsg+0x165d/0x2280
udpv6_sendmsg+0x121e/0x24f0
inet6_sendmsg+0xf7/0x140
sock_sendmsg+0xe9/0x180
____sys_sendmsg+0x2b8/0x7a0
___sys_sendmsg+0xf0/0x160
__sys_sendmmsg+0x17e/0x3c0
__x64_sys_sendmmsg+0x9e/0x100
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x462eb9
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8
 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48>
 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3df5af1c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462eb9
RDX: 0000000000000312 RSI: 0000000020001700 RDI: 0000000000000007
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3df5af26bc
R13: 00000000004c372d R14: 0000000000700b10 R15: 00000000ffffffff

It is one use-after-free in ip_check_mc_rcu.
In ip_mc_del_src, the ip_sf_list of pmc has been freed under pmc->lock protection.
But access to ip_sf_list in ip_check_mc_rcu is not protected by the lock.

Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ip_gre: add validation for csum_start 2021-09-03T08:08:13+00:00 Shreyansh Chouhan chouhan.shreyansh630@gmail.com 2021-08-21T07:14:24+00:00 53b480e68c1c2c778b620cc7f45a2ba5dff518ca [ Upstream commit 1d011c4803c72f3907eccfc1ec63caefb852fcbf ] Validate csum_start in gre_handle_offloads before we call _gre_xmit so that we do not crash later when the csum_start value is used in the lco_csum function call. This patch deals with ipv4 code. Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.") Reported-by: syzbot+ff8e1b9f2f36481e2efc@syzkaller.appspotmail.com Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 1d011c4803c72f3907eccfc1ec63caefb852fcbf ]

Validate csum_start in gre_handle_offloads before we call _gre_xmit so
that we do not crash later when the csum_start value is used in the
lco_csum function call.

This patch deals with ipv4 code.

Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.")
Reported-by: syzbot+ff8e1b9f2f36481e2efc@syzkaller.appspotmail.com
Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: igmp: increase size of mr_ifc_count 2021-08-18T06:57:01+00:00 Eric Dumazet edumazet@google.com 2021-08-11T19:57:15+00:00 4d3c5c319b197357eb6ba8346a7c82fa287bebc3 [ Upstream commit b69dd5b3780a7298bd893816a09da751bc0636f7 ] Some arches support cmpxchg() on 4-byte and 8-byte only. Increase mr_ifc_count width to 32bit to fix this problem. Fixes: 4a2b285e7e10 ("net: igmp: fix data-race in igmp_ifc_timer_expire()") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20210811195715.3684218-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit b69dd5b3780a7298bd893816a09da751bc0636f7 ]

Some arches support cmpxchg() on 4-byte and 8-byte only.
Increase mr_ifc_count width to 32bit to fix this problem.

Fixes: 4a2b285e7e10 ("net: igmp: fix data-race in igmp_ifc_timer_expire()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210811195715.3684218-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp_bbr: fix u32 wrap bug in round logic if bbr_init() called after 2B packets 2021-08-18T06:57:01+00:00 Neal Cardwell ncardwell@google.com 2021-08-11T02:40:56+00:00 721ff564cc6ab4e78d2b662060ea9c32776ed978 [ Upstream commit 6de035fec045f8ae5ee5f3a02373a18b939e91fb ] Currently if BBR congestion control is initialized after more than 2B packets have been delivered, depending on the phase of the tp->delivered counter the tracking of BBR round trips can get stuck. The bug arises because if tp->delivered is between 2^31 and 2^32 at the time the BBR congestion control module is initialized, then the initialization of bbr->next_rtt_delivered to 0 will cause the logic to believe that the end of the round trip is still billions of packets in the future. More specifically, the following check will fail repeatedly: !before(rs->prior_delivered, bbr->next_rtt_delivered) and thus the connection will take up to 2B packets delivered before that check will pass and the connection will set: bbr->round_start = 1; This could cause many mechanisms in BBR to fail to trigger, for example bbr_check_full_bw_reached() would likely never exit STARTUP. This bug is 5 years old and has not been observed, and as a practical matter this would likely rarely trigger, since it would require transferring at least 2B packets, or likely more than 3 terabytes of data, before switching congestion control algorithms to BBR. This patch is a stable candidate for kernels as far back as v4.9, when tcp_bbr.c was added. Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control") Signed-off-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Kevin Yang <yyd@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20210811024056.235161-1-ncardwell@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 6de035fec045f8ae5ee5f3a02373a18b939e91fb ]

Currently if BBR congestion control is initialized after more than 2B
packets have been delivered, depending on the phase of the
tp->delivered counter the tracking of BBR round trips can get stuck.

The bug arises because if tp->delivered is between 2^31 and 2^32 at
the time the BBR congestion control module is initialized, then the
initialization of bbr->next_rtt_delivered to 0 will cause the logic to
believe that the end of the round trip is still billions of packets in
the future. More specifically, the following check will fail
repeatedly:

  !before(rs->prior_delivered, bbr->next_rtt_delivered)

and thus the connection will take up to 2B packets delivered before
that check will pass and the connection will set:

  bbr->round_start = 1;

This could cause many mechanisms in BBR to fail to trigger, for
example bbr_check_full_bw_reached() would likely never exit STARTUP.

This bug is 5 years old and has not been observed, and as a practical
matter this would likely rarely trigger, since it would require
transferring at least 2B packets, or likely more than 3 terabytes of
data, before switching congestion control algorithms to BBR.

This patch is a stable candidate for kernels as far back as v4.9,
when tcp_bbr.c was added.

Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Kevin Yang <yyd@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20210811024056.235161-1-ncardwell@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: igmp: fix data-race in igmp_ifc_timer_expire() 2021-08-18T06:57:00+00:00 Eric Dumazet edumazet@google.com 2021-08-10T09:45:47+00:00 a9243455e874b1f077e602266603ea0422620dac [ Upstream commit 4a2b285e7e103d4d6c6ed3e5052a0ff74a5d7f15 ] Fix the data-race reported by syzbot [1] Issue here is that igmp_ifc_timer_expire() can update in_dev->mr_ifc_count while another change just occured from another context. in_dev->mr_ifc_count is only 8bit wide, so the race had little consequences. [1] BUG: KCSAN: data-race in igmp_ifc_event / igmp_ifc_timer_expire write to 0xffff8881051e3062 of 1 bytes by task 12547 on cpu 0: igmp_ifc_event+0x1d5/0x290 net/ipv4/igmp.c:821 igmp_group_added+0x462/0x490 net/ipv4/igmp.c:1356 ____ip_mc_inc_group+0x3ff/0x500 net/ipv4/igmp.c:1461 __ip_mc_join_group+0x24d/0x2c0 net/ipv4/igmp.c:2199 ip_mc_join_group_ssm+0x20/0x30 net/ipv4/igmp.c:2218 do_ip_setsockopt net/ipv4/ip_sockglue.c:1285 [inline] ip_setsockopt+0x1827/0x2a80 net/ipv4/ip_sockglue.c:1423 tcp_setsockopt+0x8c/0xa0 net/ipv4/tcp.c:3657 sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3362 __sys_setsockopt+0x18f/0x200 net/socket.c:2159 __do_sys_setsockopt net/socket.c:2170 [inline] __se_sys_setsockopt net/socket.c:2167 [inline] __x64_sys_setsockopt+0x62/0x70 net/socket.c:2167 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff8881051e3062 of 1 bytes by interrupt on cpu 1: igmp_ifc_timer_expire+0x706/0xa30 net/ipv4/igmp.c:808 call_timer_fn+0x2e/0x1d0 kernel/time/timer.c:1419 expire_timers+0x135/0x250 kernel/time/timer.c:1464 __run_timers+0x358/0x420 kernel/time/timer.c:1732 run_timer_softirq+0x19/0x30 kernel/time/timer.c:1745 __do_softirq+0x12c/0x26e kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x9a/0xb0 kernel/softirq.c:636 sysvec_apic_timer_interrupt+0x69/0x80 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 console_unlock+0x8e8/0xb30 kernel/printk/printk.c:2646 vprintk_emit+0x125/0x3d0 kernel/printk/printk.c:2174 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392 printk+0x62/0x87 kernel/printk/printk.c:2216 selinux_netlink_send+0x399/0x400 security/selinux/hooks.c:6041 security_netlink_send+0x42/0x90 security/security.c:2070 netlink_sendmsg+0x59e/0x7c0 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg net/socket.c:723 [inline] ____sys_sendmsg+0x360/0x4d0 net/socket.c:2392 ___sys_sendmsg net/socket.c:2446 [inline] __sys_sendmsg+0x1ed/0x270 net/socket.c:2475 __do_sys_sendmsg net/socket.c:2484 [inline] __se_sys_sendmsg net/socket.c:2482 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2482 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x01 -> 0x02 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 12539 Comm: syz-executor.1 Not tainted 5.14.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4a2b285e7e103d4d6c6ed3e5052a0ff74a5d7f15 ]

Fix the data-race reported by syzbot [1]
Issue here is that igmp_ifc_timer_expire() can update in_dev->mr_ifc_count
while another change just occured from another context.

in_dev->mr_ifc_count is only 8bit wide, so the race had little
consequences.

[1]
BUG: KCSAN: data-race in igmp_ifc_event / igmp_ifc_timer_expire

write to 0xffff8881051e3062 of 1 bytes by task 12547 on cpu 0:
 igmp_ifc_event+0x1d5/0x290 net/ipv4/igmp.c:821
 igmp_group_added+0x462/0x490 net/ipv4/igmp.c:1356
 ____ip_mc_inc_group+0x3ff/0x500 net/ipv4/igmp.c:1461
 __ip_mc_join_group+0x24d/0x2c0 net/ipv4/igmp.c:2199
 ip_mc_join_group_ssm+0x20/0x30 net/ipv4/igmp.c:2218
 do_ip_setsockopt net/ipv4/ip_sockglue.c:1285 [inline]
 ip_setsockopt+0x1827/0x2a80 net/ipv4/ip_sockglue.c:1423
 tcp_setsockopt+0x8c/0xa0 net/ipv4/tcp.c:3657
 sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3362
 __sys_setsockopt+0x18f/0x200 net/socket.c:2159
 __do_sys_setsockopt net/socket.c:2170 [inline]
 __se_sys_setsockopt net/socket.c:2167 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2167
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881051e3062 of 1 bytes by interrupt on cpu 1:
 igmp_ifc_timer_expire+0x706/0xa30 net/ipv4/igmp.c:808
 call_timer_fn+0x2e/0x1d0 kernel/time/timer.c:1419
 expire_timers+0x135/0x250 kernel/time/timer.c:1464
 __run_timers+0x358/0x420 kernel/time/timer.c:1732
 run_timer_softirq+0x19/0x30 kernel/time/timer.c:1745
 __do_softirq+0x12c/0x26e kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x9a/0xb0 kernel/softirq.c:636
 sysvec_apic_timer_interrupt+0x69/0x80 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
 console_unlock+0x8e8/0xb30 kernel/printk/printk.c:2646
 vprintk_emit+0x125/0x3d0 kernel/printk/printk.c:2174
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185
 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392
 printk+0x62/0x87 kernel/printk/printk.c:2216
 selinux_netlink_send+0x399/0x400 security/selinux/hooks.c:6041
 security_netlink_send+0x42/0x90 security/security.c:2070
 netlink_sendmsg+0x59e/0x7c0 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:703 [inline]
 sock_sendmsg net/socket.c:723 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2392
 ___sys_sendmsg net/socket.c:2446 [inline]
 __sys_sendmsg+0x1ed/0x270 net/socket.c:2475
 __do_sys_sendmsg net/socket.c:2484 [inline]
 __se_sys_sendmsg net/socket.c:2482 [inline]
 __x64_sys_sendmsg+0x42/0x50 net/socket.c:2482
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x01 -> 0x02

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12539 Comm: syz-executor.1 Not tainted 5.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net, gro: Set inner transport header offset in tcp/udp GRO hook 2021-08-12T11:20:56+00:00 Jakub Sitnicki jakub@cloudflare.com 2021-07-29T13:48:20+00:00 88b7781609c617aef177eef4af10126d78331db1 [ Upstream commit d51c5907e9809a803b276883d203f45849abd4d6 ] GSO expects inner transport header offset to be valid when skb->encapsulation flag is set. GSO uses this value to calculate the length of an individual segment of a GSO packet in skb_gso_transport_seglen(). However, tcp/udp gro_complete callbacks don't update the skb->inner_transport_header when processing an encapsulated TCP/UDP segment. As a result a GRO skb has ->inner_transport_header set to a value carried over from earlier skb processing. This can have mild to tragic consequences. From miscalculating the GSO segment length to triggering a page fault [1], when trying to read TCP/UDP header at an address past the skb->data page. The latter scenario leads to an oops report like so: BUG: unable to handle page fault for address: ffff9fa7ec00d008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 123f201067 P4D 123f201067 PUD 123f209067 PMD 0 Oops: 0000 [#1] SMP NOPTI CPU: 44 PID: 0 Comm: swapper/44 Not tainted 5.4.53-cloudflare-2020.7.21 #1 Hardware name: HYVE EDGE-METAL-GEN10/HS-1811DLite1, BIOS V2.15 02/21/2020 RIP: 0010:skb_gso_transport_seglen+0x44/0xa0 Code: c0 41 83 e0 11 f6 87 81 00 00 00 20 74 30 0f b7 87 aa 00 00 00 0f [...] RSP: 0018:ffffad8640bacbb8 EFLAGS: 00010202 RAX: 000000000000feda RBX: ffff9fcc8d31bc00 RCX: ffff9fa7ec00cffc RDX: ffff9fa7ebffdec0 RSI: 000000000000feda RDI: 0000000000000122 RBP: 00000000000005c4 R08: 0000000000000001 R09: 0000000000000000 R10: ffff9fe588ae3800 R11: ffff9fe011fc92f0 R12: ffff9fcc8d31bc00 R13: ffff9fe0119d4300 R14: 00000000000005c4 R15: ffff9fba57d70900 FS: 0000000000000000(0000) GS:ffff9fe68df00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff9fa7ec00d008 CR3: 0000003e99b1c000 CR4: 0000000000340ee0 Call Trace: <IRQ> skb_gso_validate_network_len+0x11/0x70 __ip_finish_output+0x109/0x1c0 ip_sublist_rcv_finish+0x57/0x70 ip_sublist_rcv+0x2aa/0x2d0 ? ip_rcv_finish_core.constprop.0+0x390/0x390 ip_list_rcv+0x12b/0x14f __netif_receive_skb_list_core+0x2a9/0x2d0 netif_receive_skb_list_internal+0x1b5/0x2e0 napi_complete_done+0x93/0x140 veth_poll+0xc0/0x19f [veth] ? mlx5e_napi_poll+0x221/0x610 [mlx5_core] net_rx_action+0x1f8/0x790 __do_softirq+0xe1/0x2bf irq_exit+0x8e/0xc0 do_IRQ+0x58/0xe0 common_interrupt+0xf/0xf </IRQ> The bug can be observed in a simple setup where we send IP/GRE/IP/TCP packets into a netns over a veth pair. Inside the netns, packets are forwarded to dummy device: trafgen -> [veth A]--[veth B] -forward-> [dummy] For veth B to GRO aggregate packets on receive, it needs to have an XDP program attached (for example, a trivial XDP_PASS). Additionally, for UDP, we need to enable GSO_UDP_L4 feature on the device: ip netns exec A ethtool -K AB rx-udp-gro-forwarding on The last component is an artificial delay to increase the chances of GRO batching happening: ip netns exec A tc qdisc add dev AB root \ netem delay 200us slot 5ms 10ms packets 2 bytes 64k With such a setup in place, the bug can be observed by tracing the skb outer and inner offsets when GSO skb is transmitted from the dummy device: tcp: FUNC DEV SKB_LEN NH TH ENC INH ITH GSO_SIZE GSO_TYPE ip_finish_output dumB 2830 270 290 1 294 254 1383 (tcpv4,gre,) ^^^ udp: FUNC DEV SKB_LEN NH TH ENC INH ITH GSO_SIZE GSO_TYPE ip_finish_output dumB 2818 270 290 1 294 254 1383 (gre,udp_l4,) ^^^ Fix it by updating the inner transport header offset in tcp/udp gro_complete callbacks, similar to how {inet,ipv6}_gro_complete callbacks update the inner network header offset, when skb->encapsulation flag is set. [1] https://lore.kernel.org/netdev/CAKxSbF01cLpZem2GFaUaifh0S-5WYViZemTicAg7FCHOnh6kug@mail.gmail.com/ Fixes: bf296b125b21 ("tcp: Add GRO support") Fixes: f993bc25e519 ("net: core: handle encapsulation offloads when computing segment lengths") Fixes: e20cf8d3f1f7 ("udp: implement GRO for plain UDP sockets.") Reported-by: Alex Forster <aforster@cloudflare.com> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d51c5907e9809a803b276883d203f45849abd4d6 ]

GSO expects inner transport header offset to be valid when
skb->encapsulation flag is set. GSO uses this value to calculate the length
of an individual segment of a GSO packet in skb_gso_transport_seglen().

However, tcp/udp gro_complete callbacks don't update the
skb->inner_transport_header when processing an encapsulated TCP/UDP
segment. As a result a GRO skb has ->inner_transport_header set to a value
carried over from earlier skb processing.

This can have mild to tragic consequences. From miscalculating the GSO
segment length to triggering a page fault [1], when trying to read TCP/UDP
header at an address past the skb->data page.

The latter scenario leads to an oops report like so:

  BUG: unable to handle page fault for address: ffff9fa7ec00d008
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 123f201067 P4D 123f201067 PUD 123f209067 PMD 0
  Oops: 0000 [#1] SMP NOPTI
  CPU: 44 PID: 0 Comm: swapper/44 Not tainted 5.4.53-cloudflare-2020.7.21 #1
  Hardware name: HYVE EDGE-METAL-GEN10/HS-1811DLite1, BIOS V2.15 02/21/2020
  RIP: 0010:skb_gso_transport_seglen+0x44/0xa0
  Code: c0 41 83 e0 11 f6 87 81 00 00 00 20 74 30 0f b7 87 aa 00 00 00 0f [...]
  RSP: 0018:ffffad8640bacbb8 EFLAGS: 00010202
  RAX: 000000000000feda RBX: ffff9fcc8d31bc00 RCX: ffff9fa7ec00cffc
  RDX: ffff9fa7ebffdec0 RSI: 000000000000feda RDI: 0000000000000122
  RBP: 00000000000005c4 R08: 0000000000000001 R09: 0000000000000000
  R10: ffff9fe588ae3800 R11: ffff9fe011fc92f0 R12: ffff9fcc8d31bc00
  R13: ffff9fe0119d4300 R14: 00000000000005c4 R15: ffff9fba57d70900
  FS:  0000000000000000(0000) GS:ffff9fe68df00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffff9fa7ec00d008 CR3: 0000003e99b1c000 CR4: 0000000000340ee0
  Call Trace:
   <IRQ>
   skb_gso_validate_network_len+0x11/0x70
   __ip_finish_output+0x109/0x1c0
   ip_sublist_rcv_finish+0x57/0x70
   ip_sublist_rcv+0x2aa/0x2d0
   ? ip_rcv_finish_core.constprop.0+0x390/0x390
   ip_list_rcv+0x12b/0x14f
   __netif_receive_skb_list_core+0x2a9/0x2d0
   netif_receive_skb_list_internal+0x1b5/0x2e0
   napi_complete_done+0x93/0x140
   veth_poll+0xc0/0x19f [veth]
   ? mlx5e_napi_poll+0x221/0x610 [mlx5_core]
   net_rx_action+0x1f8/0x790
   __do_softirq+0xe1/0x2bf
   irq_exit+0x8e/0xc0
   do_IRQ+0x58/0xe0
   common_interrupt+0xf/0xf
   </IRQ>

The bug can be observed in a simple setup where we send IP/GRE/IP/TCP
packets into a netns over a veth pair. Inside the netns, packets are
forwarded to dummy device:

  trafgen -> [veth A]--[veth B] -forward-> [dummy]

For veth B to GRO aggregate packets on receive, it needs to have an XDP
program attached (for example, a trivial XDP_PASS). Additionally, for UDP,
we need to enable GSO_UDP_L4 feature on the device:

  ip netns exec A ethtool -K AB rx-udp-gro-forwarding on

The last component is an artificial delay to increase the chances of GRO
batching happening:

  ip netns exec A tc qdisc add dev AB root \
     netem delay 200us slot 5ms 10ms packets 2 bytes 64k

With such a setup in place, the bug can be observed by tracing the skb
outer and inner offsets when GSO skb is transmitted from the dummy device:

tcp:

FUNC              DEV   SKB_LEN  NH  TH ENC INH ITH GSO_SIZE GSO_TYPE
ip_finish_output  dumB     2830 270 290   1 294 254     1383 (tcpv4,gre,)
                                                ^^^
udp:

FUNC              DEV   SKB_LEN  NH  TH ENC INH ITH GSO_SIZE GSO_TYPE
ip_finish_output  dumB     2818 270 290   1 294 254     1383 (gre,udp_l4,)
                                                ^^^

Fix it by updating the inner transport header offset in tcp/udp
gro_complete callbacks, similar to how {inet,ipv6}_gro_complete callbacks
update the inner network header offset, when skb->encapsulation flag is
set.

[1] https://lore.kernel.org/netdev/CAKxSbF01cLpZem2GFaUaifh0S-5WYViZemTicAg7FCHOnh6kug@mail.gmail.com/

Fixes: bf296b125b21 ("tcp: Add GRO support")
Fixes: f993bc25e519 ("net: core: handle encapsulation offloads when computing segment lengths")
Fixes: e20cf8d3f1f7 ("udp: implement GRO for plain UDP sockets.")
Reported-by: Alex Forster <aforster@cloudflare.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>