<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/net/ipv4/tcp_input.c, branch v6.2</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'net-next-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next</title>
<updated>2022-12-13T23:47:48+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-12-13T23:47:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7e68dd7d07a28faa2e6574dd6b9dbd90cdeaae91'/>
<id>7e68dd7d07a28faa2e6574dd6b9dbd90cdeaae91</id>
<content type='text'>
Pull networking updates from Paolo Abeni:
 "Core:

   - Allow live renaming when an interface is up

   - Add retpoline wrappers for tc, improving considerably the
     performances of complex queue discipline configurations

   - Add inet drop monitor support

   - A few GRO performance improvements

   - Add infrastructure for atomic dev stats, addressing long standing
     data races

   - De-duplicate common code between OVS and conntrack offloading
     infrastructure

   - A bunch of UBSAN_BOUNDS/FORTIFY_SOURCE improvements

   - Netfilter: introduce packet parser for tunneled packets

   - Replace IPVS timer-based estimators with kthreads to scale up the
     workload with the number of available CPUs

   - Add the helper support for connection-tracking OVS offload

  BPF:

   - Support for user defined BPF objects: the use case is to allocate
     own objects, build own object hierarchies and use the building
     blocks to build own data structures flexibly, for example, linked
     lists in BPF

   - Make cgroup local storage available to non-cgroup attached BPF
     programs

   - Avoid unnecessary deadlock detection and failures wrt BPF task
     storage helpers

   - A relevant bunch of BPF verifier fixes and improvements

   - Veristat tool improvements to support custom filtering, sorting,
     and replay of results

   - Add LLVM disassembler as default library for dumping JITed code

   - Lots of new BPF documentation for various BPF maps

   - Add bpf_rcu_read_{,un}lock() support for sleepable programs

   - Add RCU grace period chaining to BPF to wait for the completion of
     access from both sleepable and non-sleepable BPF programs

   - Add support storing struct task_struct objects as kptrs in maps

   - Improve helper UAPI by explicitly defining BPF_FUNC_xxx integer
     values

   - Add libbpf *_opts API-variants for bpf_*_get_fd_by_id() functions

  Protocols:

   - TCP: implement Protective Load Balancing across switch links

   - TCP: allow dynamically disabling TCP-MD5 static key, reverting back
     to fast[er]-path

   - UDP: Introduce optional per-netns hash lookup table

   - IPv6: simplify and cleanup sockets disposal

   - Netlink: support different type policies for each generic netlink
     operation

   - MPTCP: add MSG_FASTOPEN and FastOpen listener side support

   - MPTCP: add netlink notification support for listener sockets events

   - SCTP: add VRF support, allowing sctp sockets binding to VRF devices

   - Add bridging MAC Authentication Bypass (MAB) support

   - Extensions for Ethernet VPN bridging implementation to better
     support multicast scenarios

   - More work for Wi-Fi 7 support, comprising conversion of all the
     existing drivers to internal TX queue usage

   - IPSec: introduce a new offload type (packet offload) allowing
     complete header processing and crypto offloading

   - IPSec: extended ack support for more descriptive XFRM error
     reporting

   - RXRPC: increase SACK table size and move processing into a
     per-local endpoint kernel thread, reducing considerably the
     required locking

   - IEEE 802154: synchronous send frame and extended filtering support,
     initial support for scanning available 15.4 networks

   - Tun: bump the link speed from 10Mbps to 10Gbps

   - Tun/VirtioNet: implement UDP segmentation offload support

  Driver API:

   - PHY/SFP: improve power level switching between standard level 1 and
     the higher power levels

   - New API for netdev &lt;-&gt; devlink_port linkage

   - PTP: convert existing drivers to new frequency adjustment
     implementation

   - DSA: add support for rx offloading

   - Autoload DSA tagging driver when dynamically changing protocol

   - Add new PCP and APPTRUST attributes to Data Center Bridging

   - Add configuration support for 800Gbps link speed

   - Add devlink port function attribute to enable/disable RoCE and
     migratable

   - Extend devlink-rate to support strict prioriry and weighted fair
     queuing

   - Add devlink support to directly reading from region memory

   - New device tree helper to fetch MAC address from nvmem

   - New big TCP helper to simplify temporary header stripping

  New hardware / drivers:

   - Ethernet:
      - Marvel Octeon CNF95N and CN10KB Ethernet Switches
      - Marvel Prestera AC5X Ethernet Switch
      - WangXun 10 Gigabit NIC
      - Motorcomm yt8521 Gigabit Ethernet
      - Microchip ksz9563 Gigabit Ethernet Switch
      - Microsoft Azure Network Adapter
      - Linux Automation 10Base-T1L adapter

   - PHY:
      - Aquantia AQR112 and AQR412
      - Motorcomm YT8531S

   - PTP:
      - Orolia ART-CARD

   - WiFi:
      - MediaTek Wi-Fi 7 (802.11be) devices
      - RealTek rtw8821cu, rtw8822bu, rtw8822cu and rtw8723du USB
        devices

   - Bluetooth:
      - Broadcom BCM4377/4378/4387 Bluetooth chipsets
      - Realtek RTL8852BE and RTL8723DS
      - Cypress.CYW4373A0 WiFi + Bluetooth combo device

  Drivers:

   - CAN:
      - gs_usb: bus error reporting support
      - kvaser_usb: listen only and bus error reporting support

   - Ethernet NICs:
      - Intel (100G):
         - extend action skbedit to RX queue mapping
         - implement devlink-rate support
         - support direct read from memory
      - nVidia/Mellanox (mlx5):
         - SW steering improvements, increasing rules update rate
         - Support for enhanced events compression
         - extend H/W offload packet manipulation capabilities
         - implement IPSec packet offload mode
      - nVidia/Mellanox (mlx4):
         - better big TCP support
      - Netronome Ethernet NICs (nfp):
         - IPsec offload support
         - add support for multicast filter
      - Broadcom:
         - RSS and PTP support improvements
      - AMD/SolarFlare:
         - netlink extened ack improvements
         - add basic flower matches to offload, and related stats
      - Virtual NICs:
         - ibmvnic: introduce affinity hint support
      - small / embedded:
         - FreeScale fec: add initial XDP support
         - Marvel mv643xx_eth: support MII/GMII/RGMII modes for Kirkwood
         - TI am65-cpsw: add suspend/resume support
         - Mediatek MT7986: add RX wireless wthernet dispatch support
         - Realtek 8169: enable GRO software interrupt coalescing per
           default

   - Ethernet high-speed switches:
      - Microchip (sparx5):
         - add support for Sparx5 TC/flower H/W offload via VCAP
      - Mellanox mlxsw:
         - add 802.1X and MAC Authentication Bypass offload support
         - add ip6gre support

   - Embedded Ethernet switches:
      - Mediatek (mtk_eth_soc):
         - improve PCS implementation, add DSA untag support
         - enable flow offload support
      - Renesas:
         - add rswitch R-Car Gen4 gPTP support
      - Microchip (lan966x):
         - add full XDP support
         - add TC H/W offload via VCAP
         - enable PTP on bridge interfaces
      - Microchip (ksz8):
         - add MTU support for KSZ8 series

   - Qualcomm 802.11ax WiFi (ath11k):
      - support configuring channel dwell time during scan

   - MediaTek WiFi (mt76):
      - enable Wireless Ethernet Dispatch (WED) offload support
      - add ack signal support
      - enable coredump support
      - remain_on_channel support

   - Intel WiFi (iwlwifi):
      - enable Wi-Fi 7 Extremely High Throughput (EHT) PHY capabilities
      - 320 MHz channels support

   - RealTek WiFi (rtw89):
      - new dynamic header firmware format support
      - wake-over-WLAN support"

* tag 'net-next-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2002 commits)
  ipvs: fix type warning in do_div() on 32 bit
  net: lan966x: Remove a useless test in lan966x_ptp_add_trap()
  net: ipa: add IPA v4.7 support
  dt-bindings: net: qcom,ipa: Add SM6350 compatible
  bnxt: Use generic HBH removal helper in tx path
  IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver
  selftests: forwarding: Add bridge MDB test
  selftests: forwarding: Rename bridge_mdb test
  bridge: mcast: Support replacement of MDB port group entries
  bridge: mcast: Allow user space to specify MDB entry routing protocol
  bridge: mcast: Allow user space to add (*, G) with a source list and filter mode
  bridge: mcast: Add support for (*, G) with a source list and filter mode
  bridge: mcast: Avoid arming group timer when (S, G) corresponds to a source
  bridge: mcast: Add a flag for user installed source entries
  bridge: mcast: Expose __br_multicast_del_group_src()
  bridge: mcast: Expose br_multicast_new_group_src()
  bridge: mcast: Add a centralized error path
  bridge: mcast: Place netlink policy before validation functions
  bridge: mcast: Split (*, G) and (S, G) addition into different functions
  bridge: mcast: Do not derive entry type from its filter mode
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull networking updates from Paolo Abeni:
 "Core:

   - Allow live renaming when an interface is up

   - Add retpoline wrappers for tc, improving considerably the
     performances of complex queue discipline configurations

   - Add inet drop monitor support

   - A few GRO performance improvements

   - Add infrastructure for atomic dev stats, addressing long standing
     data races

   - De-duplicate common code between OVS and conntrack offloading
     infrastructure

   - A bunch of UBSAN_BOUNDS/FORTIFY_SOURCE improvements

   - Netfilter: introduce packet parser for tunneled packets

   - Replace IPVS timer-based estimators with kthreads to scale up the
     workload with the number of available CPUs

   - Add the helper support for connection-tracking OVS offload

  BPF:

   - Support for user defined BPF objects: the use case is to allocate
     own objects, build own object hierarchies and use the building
     blocks to build own data structures flexibly, for example, linked
     lists in BPF

   - Make cgroup local storage available to non-cgroup attached BPF
     programs

   - Avoid unnecessary deadlock detection and failures wrt BPF task
     storage helpers

   - A relevant bunch of BPF verifier fixes and improvements

   - Veristat tool improvements to support custom filtering, sorting,
     and replay of results

   - Add LLVM disassembler as default library for dumping JITed code

   - Lots of new BPF documentation for various BPF maps

   - Add bpf_rcu_read_{,un}lock() support for sleepable programs

   - Add RCU grace period chaining to BPF to wait for the completion of
     access from both sleepable and non-sleepable BPF programs

   - Add support storing struct task_struct objects as kptrs in maps

   - Improve helper UAPI by explicitly defining BPF_FUNC_xxx integer
     values

   - Add libbpf *_opts API-variants for bpf_*_get_fd_by_id() functions

  Protocols:

   - TCP: implement Protective Load Balancing across switch links

   - TCP: allow dynamically disabling TCP-MD5 static key, reverting back
     to fast[er]-path

   - UDP: Introduce optional per-netns hash lookup table

   - IPv6: simplify and cleanup sockets disposal

   - Netlink: support different type policies for each generic netlink
     operation

   - MPTCP: add MSG_FASTOPEN and FastOpen listener side support

   - MPTCP: add netlink notification support for listener sockets events

   - SCTP: add VRF support, allowing sctp sockets binding to VRF devices

   - Add bridging MAC Authentication Bypass (MAB) support

   - Extensions for Ethernet VPN bridging implementation to better
     support multicast scenarios

   - More work for Wi-Fi 7 support, comprising conversion of all the
     existing drivers to internal TX queue usage

   - IPSec: introduce a new offload type (packet offload) allowing
     complete header processing and crypto offloading

   - IPSec: extended ack support for more descriptive XFRM error
     reporting

   - RXRPC: increase SACK table size and move processing into a
     per-local endpoint kernel thread, reducing considerably the
     required locking

   - IEEE 802154: synchronous send frame and extended filtering support,
     initial support for scanning available 15.4 networks

   - Tun: bump the link speed from 10Mbps to 10Gbps

   - Tun/VirtioNet: implement UDP segmentation offload support

  Driver API:

   - PHY/SFP: improve power level switching between standard level 1 and
     the higher power levels

   - New API for netdev &lt;-&gt; devlink_port linkage

   - PTP: convert existing drivers to new frequency adjustment
     implementation

   - DSA: add support for rx offloading

   - Autoload DSA tagging driver when dynamically changing protocol

   - Add new PCP and APPTRUST attributes to Data Center Bridging

   - Add configuration support for 800Gbps link speed

   - Add devlink port function attribute to enable/disable RoCE and
     migratable

   - Extend devlink-rate to support strict prioriry and weighted fair
     queuing

   - Add devlink support to directly reading from region memory

   - New device tree helper to fetch MAC address from nvmem

   - New big TCP helper to simplify temporary header stripping

  New hardware / drivers:

   - Ethernet:
      - Marvel Octeon CNF95N and CN10KB Ethernet Switches
      - Marvel Prestera AC5X Ethernet Switch
      - WangXun 10 Gigabit NIC
      - Motorcomm yt8521 Gigabit Ethernet
      - Microchip ksz9563 Gigabit Ethernet Switch
      - Microsoft Azure Network Adapter
      - Linux Automation 10Base-T1L adapter

   - PHY:
      - Aquantia AQR112 and AQR412
      - Motorcomm YT8531S

   - PTP:
      - Orolia ART-CARD

   - WiFi:
      - MediaTek Wi-Fi 7 (802.11be) devices
      - RealTek rtw8821cu, rtw8822bu, rtw8822cu and rtw8723du USB
        devices

   - Bluetooth:
      - Broadcom BCM4377/4378/4387 Bluetooth chipsets
      - Realtek RTL8852BE and RTL8723DS
      - Cypress.CYW4373A0 WiFi + Bluetooth combo device

  Drivers:

   - CAN:
      - gs_usb: bus error reporting support
      - kvaser_usb: listen only and bus error reporting support

   - Ethernet NICs:
      - Intel (100G):
         - extend action skbedit to RX queue mapping
         - implement devlink-rate support
         - support direct read from memory
      - nVidia/Mellanox (mlx5):
         - SW steering improvements, increasing rules update rate
         - Support for enhanced events compression
         - extend H/W offload packet manipulation capabilities
         - implement IPSec packet offload mode
      - nVidia/Mellanox (mlx4):
         - better big TCP support
      - Netronome Ethernet NICs (nfp):
         - IPsec offload support
         - add support for multicast filter
      - Broadcom:
         - RSS and PTP support improvements
      - AMD/SolarFlare:
         - netlink extened ack improvements
         - add basic flower matches to offload, and related stats
      - Virtual NICs:
         - ibmvnic: introduce affinity hint support
      - small / embedded:
         - FreeScale fec: add initial XDP support
         - Marvel mv643xx_eth: support MII/GMII/RGMII modes for Kirkwood
         - TI am65-cpsw: add suspend/resume support
         - Mediatek MT7986: add RX wireless wthernet dispatch support
         - Realtek 8169: enable GRO software interrupt coalescing per
           default

   - Ethernet high-speed switches:
      - Microchip (sparx5):
         - add support for Sparx5 TC/flower H/W offload via VCAP
      - Mellanox mlxsw:
         - add 802.1X and MAC Authentication Bypass offload support
         - add ip6gre support

   - Embedded Ethernet switches:
      - Mediatek (mtk_eth_soc):
         - improve PCS implementation, add DSA untag support
         - enable flow offload support
      - Renesas:
         - add rswitch R-Car Gen4 gPTP support
      - Microchip (lan966x):
         - add full XDP support
         - add TC H/W offload via VCAP
         - enable PTP on bridge interfaces
      - Microchip (ksz8):
         - add MTU support for KSZ8 series

   - Qualcomm 802.11ax WiFi (ath11k):
      - support configuring channel dwell time during scan

   - MediaTek WiFi (mt76):
      - enable Wireless Ethernet Dispatch (WED) offload support
      - add ack signal support
      - enable coredump support
      - remain_on_channel support

   - Intel WiFi (iwlwifi):
      - enable Wi-Fi 7 Extremely High Throughput (EHT) PHY capabilities
      - 320 MHz channels support

   - RealTek WiFi (rtw89):
      - new dynamic header firmware format support
      - wake-over-WLAN support"

* tag 'net-next-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2002 commits)
  ipvs: fix type warning in do_div() on 32 bit
  net: lan966x: Remove a useless test in lan966x_ptp_add_trap()
  net: ipa: add IPA v4.7 support
  dt-bindings: net: qcom,ipa: Add SM6350 compatible
  bnxt: Use generic HBH removal helper in tx path
  IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver
  selftests: forwarding: Add bridge MDB test
  selftests: forwarding: Rename bridge_mdb test
  bridge: mcast: Support replacement of MDB port group entries
  bridge: mcast: Allow user space to specify MDB entry routing protocol
  bridge: mcast: Allow user space to add (*, G) with a source list and filter mode
  bridge: mcast: Add support for (*, G) with a source list and filter mode
  bridge: mcast: Avoid arming group timer when (S, G) corresponds to a source
  bridge: mcast: Add a flag for user installed source entries
  bridge: mcast: Expose __br_multicast_del_group_src()
  bridge: mcast: Expose br_multicast_new_group_src()
  bridge: mcast: Add a centralized error path
  bridge: mcast: Place netlink policy before validation functions
  bridge: mcast: Split (*, G) and (S, G) addition into different functions
  bridge: mcast: Do not derive entry type from its filter mode
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: Fix build break when CONFIG_IPV6=n</title>
<updated>2022-11-23T04:41:31+00:00</updated>
<author>
<name>Saeed Mahameed</name>
<email>saeedm@nvidia.com</email>
</author>
<published>2022-11-22T18:41:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c90b6b1005ec7423c7d0063eb27a9728498f6ec8'/>
<id>c90b6b1005ec7423c7d0063eb27a9728498f6ec8</id>
<content type='text'>
The cited commit caused the following build break when CONFIG_IPV6 was
disabled

net/ipv4/tcp_input.c: In function ‘tcp_syn_flood_action’:
include/net/sock.h:387:37: error: ‘const struct sock_common’ has no member named ‘skc_v6_rcv_saddr’; did you mean ‘skc_rcv_saddr’?

Fix by using inet6_rcv_saddr() macro which handles this situation
nicely.

Fixes: d9282e48c608 ("tcp: Add listening address to SYN flood message")
Signed-off-by: Saeed Mahameed &lt;saeedm@nvidia.com&gt;
Reported-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
CC: Matthieu Baerts &lt;matthieu.baerts@tessares.net&gt;
CC: Jamie Bainbridge &lt;jamie.bainbridge@gmail.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Link: https://lore.kernel.org/r/20221122184158.170798-1-saeed@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The cited commit caused the following build break when CONFIG_IPV6 was
disabled

net/ipv4/tcp_input.c: In function ‘tcp_syn_flood_action’:
include/net/sock.h:387:37: error: ‘const struct sock_common’ has no member named ‘skc_v6_rcv_saddr’; did you mean ‘skc_rcv_saddr’?

Fix by using inet6_rcv_saddr() macro which handles this situation
nicely.

Fixes: d9282e48c608 ("tcp: Add listening address to SYN flood message")
Signed-off-by: Saeed Mahameed &lt;saeedm@nvidia.com&gt;
Reported-by: Geert Uytterhoeven &lt;geert+renesas@glider.be&gt;
CC: Matthieu Baerts &lt;matthieu.baerts@tessares.net&gt;
CC: Jamie Bainbridge &lt;jamie.bainbridge@gmail.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Link: https://lore.kernel.org/r/20221122184158.170798-1-saeed@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>treewide: use get_random_u32_inclusive() when possible</title>
<updated>2022-11-18T01:18:02+00:00</updated>
<author>
<name>Jason A. Donenfeld</name>
<email>Jason@zx2c4.com</email>
</author>
<published>2022-10-10T02:44:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=e8a533cbeb79809206f8724e89961e0079508c3c'/>
<id>e8a533cbeb79809206f8724e89961e0079508c3c</id>
<content type='text'>
These cases were done with this Coccinelle:

@@
expression H;
expression L;
@@
- (get_random_u32_below(H) + L)
+ get_random_u32_inclusive(L, H + L - 1)

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- + E
- - E
  )

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- - E
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- - E
  + F
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- + E
  + F
- - E
  )

And then subsequently cleaned up by hand, with several automatic cases
rejected if it didn't make sense contextually.

Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Reviewed-by: Jason Gunthorpe &lt;jgg@nvidia.com&gt; # for infiniband
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
These cases were done with this Coccinelle:

@@
expression H;
expression L;
@@
- (get_random_u32_below(H) + L)
+ get_random_u32_inclusive(L, H + L - 1)

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- + E
- - E
  )

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- - E
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- - E
  + F
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- + E
  + F
- - E
  )

And then subsequently cleaned up by hand, with several automatic cases
rejected if it didn't make sense contextually.

Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Reviewed-by: Jason Gunthorpe &lt;jgg@nvidia.com&gt; # for infiniband
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>treewide: use get_random_u32_below() instead of deprecated function</title>
<updated>2022-11-18T01:15:15+00:00</updated>
<author>
<name>Jason A. Donenfeld</name>
<email>Jason@zx2c4.com</email>
</author>
<published>2022-10-10T02:44:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8032bf1233a74627ce69b803608e650f3f35971c'/>
<id>8032bf1233a74627ce69b803608e650f3f35971c</id>
<content type='text'>
This is a simple mechanical transformation done by:

@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
  (E)

Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Acked-by: Darrick J. Wong &lt;djwong@kernel.org&gt; # for xfs
Reviewed-by: SeongJae Park &lt;sj@kernel.org&gt; # for damon
Reviewed-by: Jason Gunthorpe &lt;jgg@nvidia.com&gt; # for infiniband
Reviewed-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt; # for arm
Acked-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt; # for mmc
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is a simple mechanical transformation done by:

@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
  (E)

Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Acked-by: Darrick J. Wong &lt;djwong@kernel.org&gt; # for xfs
Reviewed-by: SeongJae Park &lt;sj@kernel.org&gt; # for damon
Reviewed-by: Jason Gunthorpe &lt;jgg@nvidia.com&gt; # for infiniband
Reviewed-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt; # for arm
Acked-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt; # for mmc
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: annotate data-race around queue-&gt;synflood_warned</title>
<updated>2022-11-16T13:32:53+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2022-11-15T09:18:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bf36267e3ad3df80a3a18eb0422723069a434934'/>
<id>bf36267e3ad3df80a3a18eb0422723069a434934</id>
<content type='text'>
Annotate the lockless read of queue-&gt;synflood_warned.

Following xchg() has the needed data-race resolution.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Annotate the lockless read of queue-&gt;synflood_warned.

Following xchg() has the needed data-race resolution.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: Add listening address to SYN flood message</title>
<updated>2022-11-15T04:53:43+00:00</updated>
<author>
<name>Jamie Bainbridge</name>
<email>jamie.bainbridge@gmail.com</email>
</author>
<published>2022-11-14T01:00:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d9282e48c6088105a98b98153a707fdbcdbf75b1'/>
<id>d9282e48c6088105a98b98153a707fdbcdbf75b1</id>
<content type='text'>
The SYN flood message prints the listening port number, but with many
processes bound to the same port on different IPs, it's impossible to
tell which socket is the problem.

Add the listen IP address to the SYN flood message.

For IPv6 use "[IP]:port" as per RFC-5952 and to provide ease of
copy-paste to "ss" filters. For IPv4 use "IP:port" to match.

Each protcol's "any" address and a host address now look like:

 Possible SYN flooding on port 0.0.0.0:9001.
 Possible SYN flooding on port 127.0.0.1:9001.
 Possible SYN flooding on port [::]:9001.
 Possible SYN flooding on port [fc00::1]:9001.

Signed-off-by: Jamie Bainbridge &lt;jamie.bainbridge@gmail.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: Stephen Hemminger &lt;stephen@networkplumber.org&gt;
Link: https://lore.kernel.org/r/4fedab7ce54a389aeadbdc639f6b4f4988e9d2d7.1668386107.git.jamie.bainbridge@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The SYN flood message prints the listening port number, but with many
processes bound to the same port on different IPs, it's impossible to
tell which socket is the problem.

Add the listen IP address to the SYN flood message.

For IPv6 use "[IP]:port" as per RFC-5952 and to provide ease of
copy-paste to "ss" filters. For IPv4 use "IP:port" to match.

Each protcol's "any" address and a host address now look like:

 Possible SYN flooding on port 0.0.0.0:9001.
 Possible SYN flooding on port 127.0.0.1:9001.
 Possible SYN flooding on port [::]:9001.
 Possible SYN flooding on port [fc00::1]:9001.

Signed-off-by: Jamie Bainbridge &lt;jamie.bainbridge@gmail.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: Stephen Hemminger &lt;stephen@networkplumber.org&gt;
Link: https://lore.kernel.org/r/4fedab7ce54a389aeadbdc639f6b4f4988e9d2d7.1668386107.git.jamie.bainbridge@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: refine tcp_prune_ofo_queue() logic</title>
<updated>2022-11-02T04:19:58+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2022-11-01T03:52:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b0e01253a764faab9ecf56c0759e6b06470eb9ff'/>
<id>b0e01253a764faab9ecf56c0759e6b06470eb9ff</id>
<content type='text'>
After commits 36a6503fedda ("tcp: refine tcp_prune_ofo_queue()
to not drop all packets") and 72cd43ba64fc1
("tcp: free batches of packets in tcp_prune_ofo_queue()")
tcp_prune_ofo_queue() drops a fraction of ooo queue,
to make room for incoming packet.

However it makes no sense to drop packets that are
before the incoming packet, in sequence space.

In order to recover from packet losses faster,
it makes more sense to only drop ooo packets
which are after the incoming packet.

Tested:
packetdrill test:
   0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
   +0 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [3800], 4) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 &lt; S 0:0(0) win 32792 &lt;mss 1000,sackOK,nop,nop,nop,wscale 7&gt;
   +0 &gt; S. 0:0(0) ack 1 &lt;mss 1460,nop,nop,sackOK,nop,wscale 0&gt;
  +.1 &lt; . 1:1(0) ack 1 win 1024
   +0 accept(3, ..., ...) = 4

 +.01 &lt; . 200:300(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 200:300&gt;

 +.01 &lt; . 400:500(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 400:500 200:300&gt;

 +.01 &lt; . 600:700(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 600:700 400:500 200:300&gt;

 +.01 &lt; . 800:900(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 800:900 600:700 400:500 200:300&gt;

 +.01 &lt; . 1000:1100(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 1000:1100 800:900 600:700 400:500&gt;

 +.01 &lt; . 1200:1300(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 1200:1300 1000:1100 800:900 600:700&gt;

// this packet is dropped because we have no room left.
 +.01 &lt; . 1400:1500(100) ack 1 win 1024

 +.01 &lt; . 1:200(199) ack 1 win 1024
// Make sure kernel did not drop 200:300 sequence
   +0 &gt; . 1:1(0) ack 300 &lt;nop,nop, sack 1200:1300 1000:1100 800:900 600:700&gt;
// Make room, since our RCVBUF is very small
   +0 read(4, ..., 299) = 299

 +.01 &lt; . 300:400(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 500 &lt;nop,nop, sack 1200:1300 1000:1100 800:900 600:700&gt;

 +.01 &lt; . 500:600(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 700 &lt;nop,nop, sack 1200:1300 1000:1100 800:900&gt;

   +0 read(4, ..., 400) = 400

 +.01 &lt; . 700:800(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 900 &lt;nop,nop, sack 1200:1300 1000:1100&gt;

 +.01 &lt; . 900:1000(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1100 &lt;nop,nop, sack 1200:1300&gt;

 +.01 &lt; . 1100:1200(100) ack 1 win 1024
// This checks that 1200:1300 has not been removed from ooo queue
   +0 &gt; . 1:1(0) ack 1300

Suggested-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Soheil Hassas Yeganeh &lt;soheil@google.com&gt;
Acked-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Link: https://lore.kernel.org/r/20221101035234.3910189-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
After commits 36a6503fedda ("tcp: refine tcp_prune_ofo_queue()
to not drop all packets") and 72cd43ba64fc1
("tcp: free batches of packets in tcp_prune_ofo_queue()")
tcp_prune_ofo_queue() drops a fraction of ooo queue,
to make room for incoming packet.

However it makes no sense to drop packets that are
before the incoming packet, in sequence space.

In order to recover from packet losses faster,
it makes more sense to only drop ooo packets
which are after the incoming packet.

Tested:
packetdrill test:
   0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
   +0 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [3800], 4) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 &lt; S 0:0(0) win 32792 &lt;mss 1000,sackOK,nop,nop,nop,wscale 7&gt;
   +0 &gt; S. 0:0(0) ack 1 &lt;mss 1460,nop,nop,sackOK,nop,wscale 0&gt;
  +.1 &lt; . 1:1(0) ack 1 win 1024
   +0 accept(3, ..., ...) = 4

 +.01 &lt; . 200:300(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 200:300&gt;

 +.01 &lt; . 400:500(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 400:500 200:300&gt;

 +.01 &lt; . 600:700(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 600:700 400:500 200:300&gt;

 +.01 &lt; . 800:900(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 800:900 600:700 400:500 200:300&gt;

 +.01 &lt; . 1000:1100(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 1000:1100 800:900 600:700 400:500&gt;

 +.01 &lt; . 1200:1300(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1 &lt;nop,nop, sack 1200:1300 1000:1100 800:900 600:700&gt;

// this packet is dropped because we have no room left.
 +.01 &lt; . 1400:1500(100) ack 1 win 1024

 +.01 &lt; . 1:200(199) ack 1 win 1024
// Make sure kernel did not drop 200:300 sequence
   +0 &gt; . 1:1(0) ack 300 &lt;nop,nop, sack 1200:1300 1000:1100 800:900 600:700&gt;
// Make room, since our RCVBUF is very small
   +0 read(4, ..., 299) = 299

 +.01 &lt; . 300:400(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 500 &lt;nop,nop, sack 1200:1300 1000:1100 800:900 600:700&gt;

 +.01 &lt; . 500:600(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 700 &lt;nop,nop, sack 1200:1300 1000:1100 800:900&gt;

   +0 read(4, ..., 400) = 400

 +.01 &lt; . 700:800(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 900 &lt;nop,nop, sack 1200:1300 1000:1100&gt;

 +.01 &lt; . 900:1000(100) ack 1 win 1024
   +0 &gt; . 1:1(0) ack 1100 &lt;nop,nop, sack 1200:1300&gt;

 +.01 &lt; . 1100:1200(100) ack 1 win 1024
// This checks that 1200:1300 has not been removed from ooo queue
   +0 &gt; . 1:1(0) ack 1300

Suggested-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Soheil Hassas Yeganeh &lt;soheil@google.com&gt;
Acked-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Link: https://lore.kernel.org/r/20221101035234.3910189-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: fix indefinite deferral of RTO with SACK reneging</title>
<updated>2022-10-24T17:34:48+00:00</updated>
<author>
<name>Neal Cardwell</name>
<email>ncardwell@google.com</email>
</author>
<published>2022-10-21T17:08:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3d2af9cce3133b3bc596a9d065c6f9d93419ccfb'/>
<id>3d2af9cce3133b3bc596a9d065c6f9d93419ccfb</id>
<content type='text'>
This commit fixes a bug that can cause a TCP data sender to repeatedly
defer RTOs when encountering SACK reneging.

The bug is that when we're in fast recovery in a scenario with SACK
reneging, every time we get an ACK we call tcp_check_sack_reneging()
and it can note the apparent SACK reneging and rearm the RTO timer for
srtt/2 into the future. In some SACK reneging scenarios that can
happen repeatedly until the receive window fills up, at which point
the sender can't send any more, the ACKs stop arriving, and the RTO
fires at srtt/2 after the last ACK. But that can take far too long
(O(10 secs)), since the connection is stuck in fast recovery with a
low cwnd that cannot grow beyond ssthresh, even if more bandwidth is
available.

This fix changes the logic in tcp_check_sack_reneging() to only rearm
the RTO timer if data is cumulatively ACKed, indicating forward
progress. This avoids this kind of nearly infinite loop of RTO timer
re-arming. In addition, this meets the goals of
tcp_check_sack_reneging() in handling Windows TCP behavior that looks
temporarily like SACK reneging but is not really.

Many thanks to Jakub Kicinski and Neil Spring, who reported this issue
and provided critical packet traces that enabled root-causing this
issue. Also, many thanks to Jakub Kicinski for testing this fix.

Fixes: 5ae344c949e7 ("tcp: reduce spurious retransmits due to transient SACK reneging")
Reported-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Reported-by: Neil Spring &lt;ntspring@fb.com&gt;
Signed-off-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Yuchung Cheng &lt;ycheng@google.com&gt;
Tested-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Link: https://lore.kernel.org/r/20221021170821.1093930-1-ncardwell.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This commit fixes a bug that can cause a TCP data sender to repeatedly
defer RTOs when encountering SACK reneging.

The bug is that when we're in fast recovery in a scenario with SACK
reneging, every time we get an ACK we call tcp_check_sack_reneging()
and it can note the apparent SACK reneging and rearm the RTO timer for
srtt/2 into the future. In some SACK reneging scenarios that can
happen repeatedly until the receive window fills up, at which point
the sender can't send any more, the ACKs stop arriving, and the RTO
fires at srtt/2 after the last ACK. But that can take far too long
(O(10 secs)), since the connection is stuck in fast recovery with a
low cwnd that cannot grow beyond ssthresh, even if more bandwidth is
available.

This fix changes the logic in tcp_check_sack_reneging() to only rearm
the RTO timer if data is cumulatively ACKed, indicating forward
progress. This avoids this kind of nearly infinite loop of RTO timer
re-arming. In addition, this meets the goals of
tcp_check_sack_reneging() in handling Windows TCP behavior that looks
temporarily like SACK reneging but is not really.

Many thanks to Jakub Kicinski and Neil Spring, who reported this issue
and provided critical packet traces that enabled root-causing this
issue. Also, many thanks to Jakub Kicinski for testing this fix.

Fixes: 5ae344c949e7 ("tcp: reduce spurious retransmits due to transient SACK reneging")
Reported-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Reported-by: Neil Spring &lt;ntspring@fb.com&gt;
Signed-off-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Yuchung Cheng &lt;ycheng@google.com&gt;
Tested-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Link: https://lore.kernel.org/r/20221021170821.1093930-1-ncardwell.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: fix early ETIMEDOUT after spurious non-SACK RTO</title>
<updated>2022-09-06T09:06:31+00:00</updated>
<author>
<name>Neal Cardwell</name>
<email>ncardwell@google.com</email>
</author>
<published>2022-09-03T12:10:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=686dc2db2a0fdc1d34b424ec2c0a735becd8d62b'/>
<id>686dc2db2a0fdc1d34b424ec2c0a735becd8d62b</id>
<content type='text'>
Fix a bug reported and analyzed by Nagaraj Arankal, where the handling
of a spurious non-SACK RTO could cause a connection to fail to clear
retrans_stamp, causing a later RTO to very prematurely time out the
connection with ETIMEDOUT.

Here is the buggy scenario, expanding upon Nagaraj Arankal's excellent
report:

(*1) Send one data packet on a non-SACK connection

(*2) Because no ACK packet is received, the packet is retransmitted
     and we enter CA_Loss; but this retransmission is spurious.

(*3) The ACK for the original data is received. The transmitted packet
     is acknowledged.  The TCP timestamp is before the retrans_stamp,
     so tcp_may_undo() returns true, and tcp_try_undo_loss() returns
     true without changing state to Open (because tcp_is_sack() is
     false), and tcp_process_loss() returns without calling
     tcp_try_undo_recovery().  Normally after undoing a CA_Loss
     episode, tcp_fastretrans_alert() would see that the connection
     has returned to CA_Open and fall through and call
     tcp_try_to_open(), which would set retrans_stamp to 0.  However,
     for non-SACK connections we hold the connection in CA_Loss, so do
     not fall through to call tcp_try_to_open() and do not set
     retrans_stamp to 0. So retrans_stamp is (erroneously) still
     non-zero.

     At this point the first "retransmission event" has passed and
     been recovered from. Any future retransmission is a completely
     new "event". However, retrans_stamp is erroneously still
     set. (And we are still in CA_Loss, which is correct.)

(*4) After 16 minutes (to correspond with tcp_retries2=15), a new data
     packet is sent. Note: No data is transmitted between (*3) and
     (*4) and we disabled keep alives.

     The socket's timeout SHOULD be calculated from this point in
     time, but instead it's calculated from the prior "event" 16
     minutes ago (step (*2)).

(*5) Because no ACK packet is received, the packet is retransmitted.

(*6) At the time of the 2nd retransmission, the socket returns
     ETIMEDOUT, prematurely, because retrans_stamp is (erroneously)
     too far in the past (set at the time of (*2)).

This commit fixes this bug by ensuring that we reuse in
tcp_try_undo_loss() the same careful logic for non-SACK connections
that we have in tcp_try_undo_recovery(). To avoid duplicating logic,
we factor out that logic into a new
tcp_is_non_sack_preventing_reopen() helper and call that helper from
both undo functions.

Fixes: da34ac7626b5 ("tcp: only undo on partial ACKs in CA_Loss")
Reported-by: Nagaraj Arankal &lt;nagaraj.p.arankal@hpe.com&gt;
Link: https://lore.kernel.org/all/SJ0PR84MB1847BE6C24D274C46A1B9B0EB27A9@SJ0PR84MB1847.NAMPRD84.PROD.OUTLOOK.COM/
Signed-off-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Signed-off-by: Yuchung Cheng &lt;ycheng@google.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Link: https://lore.kernel.org/r/20220903121023.866900-1-ncardwell.kernel@gmail.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Fix a bug reported and analyzed by Nagaraj Arankal, where the handling
of a spurious non-SACK RTO could cause a connection to fail to clear
retrans_stamp, causing a later RTO to very prematurely time out the
connection with ETIMEDOUT.

Here is the buggy scenario, expanding upon Nagaraj Arankal's excellent
report:

(*1) Send one data packet on a non-SACK connection

(*2) Because no ACK packet is received, the packet is retransmitted
     and we enter CA_Loss; but this retransmission is spurious.

(*3) The ACK for the original data is received. The transmitted packet
     is acknowledged.  The TCP timestamp is before the retrans_stamp,
     so tcp_may_undo() returns true, and tcp_try_undo_loss() returns
     true without changing state to Open (because tcp_is_sack() is
     false), and tcp_process_loss() returns without calling
     tcp_try_undo_recovery().  Normally after undoing a CA_Loss
     episode, tcp_fastretrans_alert() would see that the connection
     has returned to CA_Open and fall through and call
     tcp_try_to_open(), which would set retrans_stamp to 0.  However,
     for non-SACK connections we hold the connection in CA_Loss, so do
     not fall through to call tcp_try_to_open() and do not set
     retrans_stamp to 0. So retrans_stamp is (erroneously) still
     non-zero.

     At this point the first "retransmission event" has passed and
     been recovered from. Any future retransmission is a completely
     new "event". However, retrans_stamp is erroneously still
     set. (And we are still in CA_Loss, which is correct.)

(*4) After 16 minutes (to correspond with tcp_retries2=15), a new data
     packet is sent. Note: No data is transmitted between (*3) and
     (*4) and we disabled keep alives.

     The socket's timeout SHOULD be calculated from this point in
     time, but instead it's calculated from the prior "event" 16
     minutes ago (step (*2)).

(*5) Because no ACK packet is received, the packet is retransmitted.

(*6) At the time of the 2nd retransmission, the socket returns
     ETIMEDOUT, prematurely, because retrans_stamp is (erroneously)
     too far in the past (set at the time of (*2)).

This commit fixes this bug by ensuring that we reuse in
tcp_try_undo_loss() the same careful logic for non-SACK connections
that we have in tcp_try_undo_recovery(). To avoid duplicating logic,
we factor out that logic into a new
tcp_is_non_sack_preventing_reopen() helper and call that helper from
both undo functions.

Fixes: da34ac7626b5 ("tcp: only undo on partial ACKs in CA_Loss")
Reported-by: Nagaraj Arankal &lt;nagaraj.p.arankal@hpe.com&gt;
Link: https://lore.kernel.org/all/SJ0PR84MB1847BE6C24D274C46A1B9B0EB27A9@SJ0PR84MB1847.NAMPRD84.PROD.OUTLOOK.COM/
Signed-off-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Signed-off-by: Yuchung Cheng &lt;ycheng@google.com&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Link: https://lore.kernel.org/r/20220903121023.866900-1-ncardwell.kernel@gmail.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: make global challenge ack rate limitation per net-ns and default disabled</title>
<updated>2022-09-01T02:56:48+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2022-08-30T18:56:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=79e3602caa6f9d59c4f66a268407080496dae408'/>
<id>79e3602caa6f9d59c4f66a268407080496dae408</id>
<content type='text'>
Because per host rate limiting has been proven problematic (side channel
attacks can be based on it), per host rate limiting of challenge acks ideally
should be per netns and turned off by default.

This is a long due followup of following commits:

083ae308280d ("tcp: enable per-socket rate limiting of all 'challenge acks'")
f2b2c582e824 ("tcp: mitigate ACK loops for connections as tcp_sock")
75ff39ccc1bd ("tcp: make challenge acks less predictable")

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Jason Baron &lt;jbaron@akamai.com&gt;
Acked-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Because per host rate limiting has been proven problematic (side channel
attacks can be based on it), per host rate limiting of challenge acks ideally
should be per netns and turned off by default.

This is a long due followup of following commits:

083ae308280d ("tcp: enable per-socket rate limiting of all 'challenge acks'")
f2b2c582e824 ("tcp: mitigate ACK loops for connections as tcp_sock")
75ff39ccc1bd ("tcp: make challenge acks less predictable")

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Jason Baron &lt;jbaron@akamai.com&gt;
Acked-by: Neal Cardwell &lt;ncardwell@google.com&gt;
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
