linux/include
Eric Dumazet f4dca95fc0 tcp: reduce accepted window in NEW_SYN_RECV state
Jason commit made checks against ACK sequence less strict
and can be exploited by attackers to establish spoofed flows
with less probes.

Innocent users might use tcp_rmem[1] == 1,000,000,000,
or something more reasonable.

An attacker can use a regular TCP connection to learn the server
initial tp->rcv_wnd, and use it to optimize the attack.

If we make sure that only the announced window (smaller than 65535)
is used for ACK validation, we force an attacker to use
65537 packets to complete the 3WHS (assuming server ISN is unknown)

Fixes: 378979e94e ("tcp: remove 64 KByte limit for initial tp->rcv_wnd value")
Link: https://datatracker.ietf.org/meeting/119/materials/slides-119-tcpm-ghost-acks-00
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://lore.kernel.org/r/20240523130528.60376-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-05-27 16:47:23 -07:00
..
acpi The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
asm-generic asm-generic cleanups for 6.10 2024-05-20 15:18:34 -07:00
clocksource
crypto This push fixes a bug in the new ecc P521 code as well as a buggy 2024-05-20 08:47:54 -07:00
drm USB / Thunderbolt changes for 6.10-rc1 2024-05-22 11:40:09 -07:00
dt-bindings - Core Frameworks 2024-05-22 10:49:54 -07:00
keys
kunit
kvm
linux bpf-for-netdev 2024-05-27 16:26:30 -07:00
math-emu
media
memory
misc
net tcp: reduce accepted window in NEW_SYN_RECV state 2024-05-27 16:47:23 -07:00
pcmcia
ras tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
rdma The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
rv
scsi SCSI misc on 20240514 2024-05-14 18:25:53 -07:00
soc I'm actually surprised this time. There aren't any new Qualcomm SoC clk 2024-05-18 12:48:37 -07:00
sound
target
trace tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
uapi connector: Fix invalid conversion in cn_proc.h 2024-05-24 10:36:55 +01:00
ufs
vdso
video
xen