linux-stable.git/net/ipv4, branch v5.4.201 Linux kernel stable tree tcp: drop the hash_32() part from the index calculation 2022-06-25T10:44:36+00:00 Willy Tarreau w@1wt.eu 2022-05-02T08:46:14+00:00 2e1591c27b954f1f60ef8ce5d214e8fee1b4d304 commit e8161345ddbb66e449abde10d2fdce93f867eba9 upstream. In commit 190cc82489f4 ("tcp: change source port randomizarion at connect() time"), the table_perturb[] array was introduced and an index was taken from the port_offset via hash_32(). But it turns out that hash_32() performs a multiplication while the input here comes from the output of SipHash in secure_seq, that is well distributed enough to avoid the need for yet another hash. Suggested-by: Amit Klein <aksecurity@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e8161345ddbb66e449abde10d2fdce93f867eba9 upstream.

In commit 190cc82489f4 ("tcp: change source port randomizarion at
connect() time"), the table_perturb[] array was introduced and an
index was taken from the port_offset via hash_32(). But it turns
out that hash_32() performs a multiplication while the input here
comes from the output of SipHash in secure_seq, that is well
distributed enough to avoid the need for yet another hash.

Suggested-by: Amit Klein <aksecurity@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: increase source port perturb table to 2^16 2022-06-25T10:44:36+00:00 Willy Tarreau w@1wt.eu 2022-05-02T08:46:13+00:00 c26e1addf15763ae404f4bbf131719a724e768ab commit 4c2c8f03a5ab7cb04ec64724d7d176d00bcc91e5 upstream. Moshe Kol, Amit Klein, and Yossi Gilad reported being able to accurately identify a client by forcing it to emit only 40 times more connections than there are entries in the table_perturb[] table. The previous two improvements consisting in resalting the secret every 10s and adding randomness to each port selection only slightly improved the situation, and the current value of 2^8 was too small as it's not very difficult to make a client emit 10k connections in less than 10 seconds. Thus we're increasing the perturb table from 2^8 to 2^16 so that the same precision now requires 2.6M connections, which is more difficult in this time frame and harder to hide as a background activity. The impact is that the table now uses 256 kB instead of 1 kB, which could mostly affect devices making frequent outgoing connections. However such components usually target a small set of destinations (load balancers, database clients, perf assessment tools), and in practice only a few entries will be visited, like before. A live test at 1 million connections per second showed no performance difference from the previous value. Reported-by: Moshe Kol <moshe.kol@mail.huji.ac.il> Reported-by: Yossi Gilad <yossi.gilad@mail.huji.ac.il> Reported-by: Amit Klein <aksecurity@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4c2c8f03a5ab7cb04ec64724d7d176d00bcc91e5 upstream.

Moshe Kol, Amit Klein, and Yossi Gilad reported being able to accurately
identify a client by forcing it to emit only 40 times more connections
than there are entries in the table_perturb[] table. The previous two
improvements consisting in resalting the secret every 10s and adding
randomness to each port selection only slightly improved the situation,
and the current value of 2^8 was too small as it's not very difficult
to make a client emit 10k connections in less than 10 seconds.

Thus we're increasing the perturb table from 2^8 to 2^16 so that the
same precision now requires 2.6M connections, which is more difficult in
this time frame and harder to hide as a background activity. The impact
is that the table now uses 256 kB instead of 1 kB, which could mostly
affect devices making frequent outgoing connections. However such
components usually target a small set of destinations (load balancers,
database clients, perf assessment tools), and in practice only a few
entries will be visited, like before.

A live test at 1 million connections per second showed no performance
difference from the previous value.

Reported-by: Moshe Kol <moshe.kol@mail.huji.ac.il>
Reported-by: Yossi Gilad <yossi.gilad@mail.huji.ac.il>
Reported-by: Amit Klein <aksecurity@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: dynamically allocate the perturb table used by source ports 2022-06-25T10:44:36+00:00 Willy Tarreau w@1wt.eu 2022-05-02T08:46:12+00:00 77d29f3b18c466a6b88bdfceccec3085961a7d0e commit e9261476184be1abd486c9434164b2acbe0ed6c2 upstream. We'll need to further increase the size of this table and it's likely that at some point its size will not be suitable anymore for a static table. Let's allocate it on boot from inet_hashinfo2_init(), which is called from tcp_init(). Cc: Moshe Kol <moshe.kol@mail.huji.ac.il> Cc: Yossi Gilad <yossi.gilad@mail.huji.ac.il> Cc: Amit Klein <aksecurity@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e9261476184be1abd486c9434164b2acbe0ed6c2 upstream.

We'll need to further increase the size of this table and it's likely
that at some point its size will not be suitable anymore for a static
table. Let's allocate it on boot from inet_hashinfo2_init(), which is
called from tcp_init().

Cc: Moshe Kol <moshe.kol@mail.huji.ac.il>
Cc: Yossi Gilad <yossi.gilad@mail.huji.ac.il>
Cc: Amit Klein <aksecurity@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: add small random increments to the source port 2022-06-25T10:44:36+00:00 Willy Tarreau w@1wt.eu 2022-05-02T08:46:11+00:00 7c0a777b7dbdcd39eb45996afe6df7770f7926ac commit ca7af0402550f9a0b3316d5f1c30904e42ed257d upstream. Here we're randomly adding between 0 and 7 random increments to the selected source port in order to add some noise in the source port selection that will make the next port less predictable. With the default port range of 32768-60999 this means a worst case reuse scenario of 14116/8=1764 connections between two consecutive uses of the same port, with an average of 14116/4.5=3137. This code was stressed at more than 800000 connections per second to a fixed target with all connections closed by the client using RSTs (worst condition) and only 2 connections failed among 13 billion, despite the hash being reseeded every 10 seconds, indicating a perfectly safe situation. Cc: Moshe Kol <moshe.kol@mail.huji.ac.il> Cc: Yossi Gilad <yossi.gilad@mail.huji.ac.il> Cc: Amit Klein <aksecurity@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ca7af0402550f9a0b3316d5f1c30904e42ed257d upstream.

Here we're randomly adding between 0 and 7 random increments to the
selected source port in order to add some noise in the source port
selection that will make the next port less predictable.

With the default port range of 32768-60999 this means a worst case
reuse scenario of 14116/8=1764 connections between two consecutive
uses of the same port, with an average of 14116/4.5=3137. This code
was stressed at more than 800000 connections per second to a fixed
target with all connections closed by the client using RSTs (worst
condition) and only 2 connections failed among 13 billion, despite
the hash being reseeded every 10 seconds, indicating a perfectly
safe situation.

Cc: Moshe Kol <moshe.kol@mail.huji.ac.il>
Cc: Yossi Gilad <yossi.gilad@mail.huji.ac.il>
Cc: Amit Klein <aksecurity@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: use different parts of the port_offset for index and offset 2022-06-25T10:44:35+00:00 Willy Tarreau w@1wt.eu 2022-05-02T08:46:09+00:00 53c5de3092ade55f82ed4f5373d8a8ca115df818 commit 9e9b70ae923baf2b5e8a0ea4fd0c8451801ac526 upstream. Amit Klein suggests that we use different parts of port_offset for the table's index and the port offset so that there is no direct relation between them. Cc: Jason A. Donenfeld <Jason@zx2c4.com> Cc: Moshe Kol <moshe.kol@mail.huji.ac.il> Cc: Yossi Gilad <yossi.gilad@mail.huji.ac.il> Cc: Amit Klein <aksecurity@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 9e9b70ae923baf2b5e8a0ea4fd0c8451801ac526 upstream.

Amit Klein suggests that we use different parts of port_offset for the
table's index and the port offset so that there is no direct relation
between them.

Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Moshe Kol <moshe.kol@mail.huji.ac.il>
Cc: Yossi Gilad <yossi.gilad@mail.huji.ac.il>
Cc: Amit Klein <aksecurity@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: add some entropy in __inet_hash_connect() 2022-06-25T10:44:35+00:00 Eric Dumazet edumazet@google.com 2021-02-09T19:20:28+00:00 95921a3bab76872e8b5c6ba07903cbdbcc352cc6 commit c579bd1b4021c42ae247108f1e6f73dd3f08600c upstream. Even when implementing RFC 6056 3.3.4 (Algorithm 4: Double-Hash Port Selection Algorithm), a patient attacker could still be able to collect enough state from an otherwise idle host. Idea of this patch is to inject some noise, in the cases __inet_hash_connect() found a candidate in the first attempt. This noise should not significantly reduce the collision avoidance, and should be zero if connection table is already well used. Note that this is not implementing RFC 6056 3.3.5 because we think Algorithm 5 could hurt typical workloads. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: David Dworken <ddworken@google.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c579bd1b4021c42ae247108f1e6f73dd3f08600c upstream.

Even when implementing RFC 6056 3.3.4 (Algorithm 4: Double-Hash
Port Selection Algorithm), a patient attacker could still be able
to collect enough state from an otherwise idle host.

Idea of this patch is to inject some noise, in the
cases __inet_hash_connect() found a candidate in the first
attempt.

This noise should not significantly reduce the collision
avoidance, and should be zero if connection table
is already well used.

Note that this is not implementing RFC 6056 3.3.5
because we think Algorithm 5 could hurt typical
workloads.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: David Dworken <ddworken@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd 2022-06-14T16:12:03+00:00 Eric Dumazet edumazet@google.com 2022-05-27T21:28:29+00:00 602b338e3c3cd7f935f3f5011882961d074e5ac1 commit 11825765291a93d8e7f44230da67b9f607c777bf upstream. syzbot got a new report [1] finally pointing to a very old bug, added in initial support for MTU probing. tcp_mtu_probe() has checks about starting an MTU probe if tcp_snd_cwnd(tp) >= 11. But nothing prevents tcp_snd_cwnd(tp) to be reduced later and before the MTU probe succeeds. This bug would lead to potential zero-divides. Debugging added in commit 40570375356c ("tcp: add accessors to read/set tp->snd_cwnd") has paid off :) While we are at it, address potential overflows in this code. [1] WARNING: CPU: 1 PID: 14132 at include/net/tcp.h:1219 tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712 Modules linked in: CPU: 1 PID: 14132 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-07857-gbabf0bb978e3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:tcp_snd_cwnd_set include/net/tcp.h:1219 [inline] RIP: 0010:tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712 Code: 74 08 48 89 ef e8 da 80 17 f9 48 8b 45 00 65 48 ff 80 80 03 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 aa b0 c5 f8 <0f> 0b e9 16 fe ff ff 48 8b 4c 24 08 80 e1 07 38 c1 0f 8c c7 fc ff RSP: 0018:ffffc900079e70f8 EFLAGS: 00010287 RAX: ffffffff88c0f7f6 RBX: ffff8880756e7a80 RCX: 0000000000040000 RDX: ffffc9000c6c4000 RSI: 0000000000031f9e RDI: 0000000000031f9f RBP: 0000000000000000 R08: ffffffff88c0f606 R09: ffffc900079e7520 R10: ffffed101011226d R11: 1ffff1101011226c R12: 1ffff1100eadcf50 R13: ffff8880756e72c0 R14: 1ffff1100eadcf89 R15: dffffc0000000000 FS: 00007f643236e700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1ab3f1e2a0 CR3: 0000000064fe7000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> tcp_clean_rtx_queue+0x223a/0x2da0 net/ipv4/tcp_input.c:3356 tcp_ack+0x1962/0x3c90 net/ipv4/tcp_input.c:3861 tcp_rcv_established+0x7c8/0x1ac0 net/ipv4/tcp_input.c:5973 tcp_v6_do_rcv+0x57b/0x1210 net/ipv6/tcp_ipv6.c:1476 sk_backlog_rcv include/net/sock.h:1061 [inline] __release_sock+0x1d8/0x4c0 net/core/sock.c:2849 release_sock+0x5d/0x1c0 net/core/sock.c:3404 sk_stream_wait_memory+0x700/0xdc0 net/core/stream.c:145 tcp_sendmsg_locked+0x111d/0x3fc0 net/ipv4/tcp.c:1410 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1448 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] __sys_sendto+0x439/0x5c0 net/socket.c:2119 __do_sys_sendto net/socket.c:2131 [inline] __se_sys_sendto net/socket.c:2127 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:2127 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f6431289109 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f643236e168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f643139c100 RCX: 00007f6431289109 RDX: 00000000d0d0c2ac RSI: 0000000020000080 RDI: 000000000000000a RBP: 00007f64312e308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff372533af R14: 00007f643236e300 R15: 0000000000022000 Fixes: 5d424d5a674f ("[TCP]: MTU probing") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Acked-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 11825765291a93d8e7f44230da67b9f607c777bf upstream.

syzbot got a new report [1] finally pointing to a very old bug,
added in initial support for MTU probing.

tcp_mtu_probe() has checks about starting an MTU probe if
tcp_snd_cwnd(tp) >= 11.

But nothing prevents tcp_snd_cwnd(tp) to be reduced later
and before the MTU probe succeeds.

This bug would lead to potential zero-divides.

Debugging added in commit 40570375356c ("tcp: add accessors
to read/set tp->snd_cwnd") has paid off :)

While we are at it, address potential overflows in this code.

[1]
WARNING: CPU: 1 PID: 14132 at include/net/tcp.h:1219 tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712
Modules linked in:
CPU: 1 PID: 14132 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-07857-gbabf0bb978e3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:tcp_snd_cwnd_set include/net/tcp.h:1219 [inline]
RIP: 0010:tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712
Code: 74 08 48 89 ef e8 da 80 17 f9 48 8b 45 00 65 48 ff 80 80 03 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 aa b0 c5 f8 <0f> 0b e9 16 fe ff ff 48 8b 4c 24 08 80 e1 07 38 c1 0f 8c c7 fc ff
RSP: 0018:ffffc900079e70f8 EFLAGS: 00010287
RAX: ffffffff88c0f7f6 RBX: ffff8880756e7a80 RCX: 0000000000040000
RDX: ffffc9000c6c4000 RSI: 0000000000031f9e RDI: 0000000000031f9f
RBP: 0000000000000000 R08: ffffffff88c0f606 R09: ffffc900079e7520
R10: ffffed101011226d R11: 1ffff1101011226c R12: 1ffff1100eadcf50
R13: ffff8880756e72c0 R14: 1ffff1100eadcf89 R15: dffffc0000000000
FS:  00007f643236e700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ab3f1e2a0 CR3: 0000000064fe7000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tcp_clean_rtx_queue+0x223a/0x2da0 net/ipv4/tcp_input.c:3356
 tcp_ack+0x1962/0x3c90 net/ipv4/tcp_input.c:3861
 tcp_rcv_established+0x7c8/0x1ac0 net/ipv4/tcp_input.c:5973
 tcp_v6_do_rcv+0x57b/0x1210 net/ipv6/tcp_ipv6.c:1476
 sk_backlog_rcv include/net/sock.h:1061 [inline]
 __release_sock+0x1d8/0x4c0 net/core/sock.c:2849
 release_sock+0x5d/0x1c0 net/core/sock.c:3404
 sk_stream_wait_memory+0x700/0xdc0 net/core/stream.c:145
 tcp_sendmsg_locked+0x111d/0x3fc0 net/ipv4/tcp.c:1410
 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1448
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 __sys_sendto+0x439/0x5c0 net/socket.c:2119
 __do_sys_sendto net/socket.c:2131 [inline]
 __se_sys_sendto net/socket.c:2127 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2127
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f6431289109
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f643236e168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f643139c100 RCX: 00007f6431289109
RDX: 00000000d0d0c2ac RSI: 0000000020000080 RDI: 000000000000000a
RBP: 00007f64312e308d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff372533af R14: 00007f643236e300 R15: 0000000000022000

Fixes: 5d424d5a674f ("[TCP]: MTU probing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ip_gre: test csum_start instead of transport header 2022-06-14T16:11:58+00:00 Willem de Bruijn willemb@google.com 2022-06-06T13:21:07+00:00 3d08bc3a5d9b2106f5c8bcf1adb73147824aa006 [ Upstream commit 8d21e9963bec1aad2280cdd034c8993033ef2948 ] GRE with TUNNEL_CSUM will apply local checksum offload on CHECKSUM_PARTIAL packets. ipgre_xmit must validate csum_start after an optional skb_pull, else lco_csum may trigger an overflow. The original check was if (csum && skb_checksum_start(skb) < skb->data) return -EINVAL; This had false positives when skb_checksum_start is undefined: when ip_summed is not CHECKSUM_PARTIAL. A discussed refinement was straightforward if (csum && skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_start(skb) < skb->data) return -EINVAL; But was eventually revised more thoroughly: - restrict the check to the only branch where needed, in an uncommon GRE path that uses header_ops and calls skb_pull. - test skb_transport_header, which is set along with csum_start in skb_partial_csum_set in the normal header_ops datapath. Turns out skbs can arrive in this branch without the transport header set, e.g., through BPF redirection. Revise the check back to check csum_start directly, and only if CHECKSUM_PARTIAL. Do leave the check in the updated location. Check field regardless of whether TUNNEL_CSUM is configured. Link: https://lore.kernel.org/netdev/YS+h%2FtqCJJiQei+W@shredder/ Link: https://lore.kernel.org/all/20210902193447.94039-2-willemdebruijn.kernel@gmail.com/T/#u Fixes: 8a0ed250f911 ("ip_gre: validate csum_start only on pull") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Link: https://lore.kernel.org/r/20220606132107.3582565-1-willemdebruijn.kernel@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 8d21e9963bec1aad2280cdd034c8993033ef2948 ]

GRE with TUNNEL_CSUM will apply local checksum offload on
CHECKSUM_PARTIAL packets.

ipgre_xmit must validate csum_start after an optional skb_pull,
else lco_csum may trigger an overflow. The original check was

	if (csum && skb_checksum_start(skb) < skb->data)
		return -EINVAL;

This had false positives when skb_checksum_start is undefined:
when ip_summed is not CHECKSUM_PARTIAL. A discussed refinement
was straightforward

	if (csum && skb->ip_summed == CHECKSUM_PARTIAL &&
	    skb_checksum_start(skb) < skb->data)
		return -EINVAL;

But was eventually revised more thoroughly:
- restrict the check to the only branch where needed, in an
  uncommon GRE path that uses header_ops and calls skb_pull.
- test skb_transport_header, which is set along with csum_start
  in skb_partial_csum_set in the normal header_ops datapath.

Turns out skbs can arrive in this branch without the transport
header set, e.g., through BPF redirection.

Revise the check back to check csum_start directly, and only if
CHECKSUM_PARTIAL. Do leave the check in the updated location.
Check field regardless of whether TUNNEL_CSUM is configured.

Link: https://lore.kernel.org/netdev/YS+h%2FtqCJJiQei+W@shredder/
Link: https://lore.kernel.org/all/20210902193447.94039-2-willemdebruijn.kernel@gmail.com/T/#u
Fixes: 8a0ed250f911 ("ip_gre: validate csum_start only on pull")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://lore.kernel.org/r/20220606132107.3582565-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: xfrm: unexport __init-annotated xfrm4_protocol_init() 2022-06-14T16:11:58+00:00 Masahiro Yamada masahiroy@kernel.org 2022-06-06T04:53:54+00:00 ef6d2354de238b065d8799c80da4be9a6af18e39 [ Upstream commit 4a388f08d8784af48f352193d2b72aaf167a57a1 ] EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic. modpost used to detect it, but it has been broken for a decade. Recently, I fixed modpost so it started to warn it again, then this showed up in linux-next builds. There are two ways to fix it: - Remove __init - Remove EXPORT_SYMBOL I chose the latter for this case because the only in-tree call-site, net/ipv4/xfrm4_policy.c is never compiled as modular. (CONFIG_XFRM is boolean) Fixes: 2f32b51b609f ("xfrm: Introduce xfrm_input_afinfo to access the the callbacks properly") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4a388f08d8784af48f352193d2b72aaf167a57a1 ]

EXPORT_SYMBOL and __init is a bad combination because the .init.text
section is freed up after the initialization. Hence, modules cannot
use symbols annotated __init. The access to a freed symbol may end up
with kernel panic.

modpost used to detect it, but it has been broken for a decade.

Recently, I fixed modpost so it started to warn it again, then this
showed up in linux-next builds.

There are two ways to fix it:

  - Remove __init
  - Remove EXPORT_SYMBOL

I chose the latter for this case because the only in-tree call-site,
net/ipv4/xfrm4_policy.c is never compiled as modular.
(CONFIG_XFRM is boolean)

Fixes: 2f32b51b609f ("xfrm: Introduce xfrm_input_afinfo to access the the callbacks properly")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: tcp_rtx_synack() can be called from process context 2022-06-14T16:11:55+00:00 Eric Dumazet edumazet@google.com 2022-05-30T21:37:13+00:00 d05c2fdf8e10528bb6751bd95243e862d5402a9b [ Upstream commit 0a375c822497ed6ad6b5da0792a12a6f1af10c0b ] Laurent reported the enclosed report [1] This bug triggers with following coditions: 0) Kernel built with CONFIG_DEBUG_PREEMPT=y 1) A new passive FastOpen TCP socket is created. This FO socket waits for an ACK coming from client to be a complete ESTABLISHED one. 2) A socket operation on this socket goes through lock_sock() release_sock() dance. 3) While the socket is owned by the user in step 2), a retransmit of the SYN is received and stored in socket backlog. 4) At release_sock() time, the socket backlog is processed while in process context. 5) A SYNACK packet is cooked in response of the SYN retransmit. 6) -> tcp_rtx_synack() is called in process context. Before blamed commit, tcp_rtx_synack() was always called from BH handler, from a timer handler. Fix this by using TCP_INC_STATS() & NET_INC_STATS() which do not assume caller is in non preemptible context. [1] BUG: using __this_cpu_add() in preemptible [00000000] code: epollpep/2180 caller is tcp_rtx_synack.part.0+0x36/0xc0 CPU: 10 PID: 2180 Comm: epollpep Tainted: G OE 5.16.0-0.bpo.4-amd64 #1 Debian 5.16.12-1~bpo11+1 Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021 Call Trace: <TASK> dump_stack_lvl+0x48/0x5e check_preemption_disabled+0xde/0xe0 tcp_rtx_synack.part.0+0x36/0xc0 tcp_rtx_synack+0x8d/0xa0 ? kmem_cache_alloc+0x2e0/0x3e0 ? apparmor_file_alloc_security+0x3b/0x1f0 inet_rtx_syn_ack+0x16/0x30 tcp_check_req+0x367/0x610 tcp_rcv_state_process+0x91/0xf60 ? get_nohz_timer_target+0x18/0x1a0 ? lock_timer_base+0x61/0x80 ? preempt_count_add+0x68/0xa0 tcp_v4_do_rcv+0xbd/0x270 __release_sock+0x6d/0xb0 release_sock+0x2b/0x90 sock_setsockopt+0x138/0x1140 ? __sys_getsockname+0x7e/0xc0 ? aa_sk_perm+0x3e/0x1a0 __sys_setsockopt+0x198/0x1e0 __x64_sys_setsockopt+0x21/0x30 do_syscall_64+0x38/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Laurent Fasnacht <laurent.fasnacht@proton.ch> Acked-by: Neal Cardwell <ncardwell@google.com> Link: https://lore.kernel.org/r/20220530213713.601888-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 0a375c822497ed6ad6b5da0792a12a6f1af10c0b ]

Laurent reported the enclosed report [1]

This bug triggers with following coditions:

0) Kernel built with CONFIG_DEBUG_PREEMPT=y

1) A new passive FastOpen TCP socket is created.
   This FO socket waits for an ACK coming from client to be a complete
   ESTABLISHED one.
2) A socket operation on this socket goes through lock_sock()
   release_sock() dance.
3) While the socket is owned by the user in step 2),
   a retransmit of the SYN is received and stored in socket backlog.
4) At release_sock() time, the socket backlog is processed while
   in process context.
5) A SYNACK packet is cooked in response of the SYN retransmit.
6) -> tcp_rtx_synack() is called in process context.

Before blamed commit, tcp_rtx_synack() was always called from BH handler,
from a timer handler.

Fix this by using TCP_INC_STATS() & NET_INC_STATS()
which do not assume caller is in non preemptible context.

[1]
BUG: using __this_cpu_add() in preemptible [00000000] code: epollpep/2180
caller is tcp_rtx_synack.part.0+0x36/0xc0
CPU: 10 PID: 2180 Comm: epollpep Tainted: G           OE     5.16.0-0.bpo.4-amd64 #1  Debian 5.16.12-1~bpo11+1
Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021
Call Trace:
 <TASK>
 dump_stack_lvl+0x48/0x5e
 check_preemption_disabled+0xde/0xe0
 tcp_rtx_synack.part.0+0x36/0xc0
 tcp_rtx_synack+0x8d/0xa0
 ? kmem_cache_alloc+0x2e0/0x3e0
 ? apparmor_file_alloc_security+0x3b/0x1f0
 inet_rtx_syn_ack+0x16/0x30
 tcp_check_req+0x367/0x610
 tcp_rcv_state_process+0x91/0xf60
 ? get_nohz_timer_target+0x18/0x1a0
 ? lock_timer_base+0x61/0x80
 ? preempt_count_add+0x68/0xa0
 tcp_v4_do_rcv+0xbd/0x270
 __release_sock+0x6d/0xb0
 release_sock+0x2b/0x90
 sock_setsockopt+0x138/0x1140
 ? __sys_getsockname+0x7e/0xc0
 ? aa_sk_perm+0x3e/0x1a0
 __sys_setsockopt+0x198/0x1e0
 __x64_sys_setsockopt+0x21/0x30
 do_syscall_64+0x38/0xc0
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Laurent Fasnacht <laurent.fasnacht@proton.ch>
Acked-by: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20220530213713.601888-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>