<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/net/ipv4, branch v6.11-rc2</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-6.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net</title>
<updated>2024-08-01T16:42:09+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-08-01T16:42:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=183d46ff422ef9f3d755b6808ef3faa6d009ba3a'/>
<id>183d46ff422ef9f3d755b6808ef3faa6d009ba3a</id>
<content type='text'>
Pull networking fixes from Paolo Abeni:
 "Including fixes from wireless, bleutooth, BPF and netfilter.

  Current release - regressions:

   - core: drop bad gso csum_start and offset in virtio_net_hdr

   - wifi: mt76: fix null pointer access in mt792x_mac_link_bss_remove

   - eth: tun: add missing bpf_net_ctx_clear() in do_xdp_generic()

   - phy: aquantia: only poll GLOBAL_CFG regs on aqr113, aqr113c and
     aqr115c

  Current release - new code bugs:

   - smc: prevent UAF in inet_create()

   - bluetooth: btmtk: fix kernel crash when entering btmtk_usb_suspend

   - eth: bnxt: reject unsupported hash functions

  Previous releases - regressions:

   - sched: act_ct: take care of padding in struct zones_ht_key

   - netfilter: fix null-ptr-deref in iptable_nat_table_init().

   - tcp: adjust clamping window for applications specifying SO_RCVBUF

  Previous releases - always broken:

   - ethtool: rss: small fixes to spec and GET

   - mptcp:
      - fix signal endpoint re-add
      - pm: fix backup support in signal endpoints

   - wifi: ath12k: fix soft lockup on suspend

   - eth: bnxt_en: fix RSS logic in __bnxt_reserve_rings()

   - eth: ice: fix AF_XDP ZC timeout and concurrency issues

   - eth: mlx5:
      - fix missing lock on sync reset reload
      - fix error handling in irq_pool_request_irq"

* tag 'net-6.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (76 commits)
  mptcp: fix duplicate data handling
  mptcp: fix bad RCVPRUNED mib accounting
  ipv6: fix ndisc_is_useropt() handling for PIO
  igc: Fix double reset adapter triggered from a single taprio cmd
  net: MAINTAINERS: Demote Qualcomm IPA to "maintained"
  net: wan: fsl_qmc_hdlc: Discard received CRC
  net: wan: fsl_qmc_hdlc: Convert carrier_lock spinlock to a mutex
  net/mlx5e: Add a check for the return value from mlx5_port_set_eth_ptys
  net/mlx5e: Fix CT entry update leaks of modify header context
  net/mlx5e: Require mlx5 tc classifier action support for IPsec prio capability
  net/mlx5: Fix missing lock on sync reset reload
  net/mlx5: Lag, don't use the hardcoded value of the first port
  net/mlx5: DR, Fix 'stack guard page was hit' error in dr_rule
  net/mlx5: Fix error handling in irq_pool_request_irq
  net/mlx5: Always drain health in shutdown callback
  net: Add skbuff.h to MAINTAINERS
  r8169: don't increment tx_dropped in case of NETDEV_TX_BUSY
  netfilter: iptables: Fix potential null-ptr-deref in ip6table_nat_table_init().
  netfilter: iptables: Fix null-ptr-deref in iptable_nat_table_init().
  net: drop bad gso csum_start and offset in virtio_net_hdr
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull networking fixes from Paolo Abeni:
 "Including fixes from wireless, bleutooth, BPF and netfilter.

  Current release - regressions:

   - core: drop bad gso csum_start and offset in virtio_net_hdr

   - wifi: mt76: fix null pointer access in mt792x_mac_link_bss_remove

   - eth: tun: add missing bpf_net_ctx_clear() in do_xdp_generic()

   - phy: aquantia: only poll GLOBAL_CFG regs on aqr113, aqr113c and
     aqr115c

  Current release - new code bugs:

   - smc: prevent UAF in inet_create()

   - bluetooth: btmtk: fix kernel crash when entering btmtk_usb_suspend

   - eth: bnxt: reject unsupported hash functions

  Previous releases - regressions:

   - sched: act_ct: take care of padding in struct zones_ht_key

   - netfilter: fix null-ptr-deref in iptable_nat_table_init().

   - tcp: adjust clamping window for applications specifying SO_RCVBUF

  Previous releases - always broken:

   - ethtool: rss: small fixes to spec and GET

   - mptcp:
      - fix signal endpoint re-add
      - pm: fix backup support in signal endpoints

   - wifi: ath12k: fix soft lockup on suspend

   - eth: bnxt_en: fix RSS logic in __bnxt_reserve_rings()

   - eth: ice: fix AF_XDP ZC timeout and concurrency issues

   - eth: mlx5:
      - fix missing lock on sync reset reload
      - fix error handling in irq_pool_request_irq"

* tag 'net-6.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (76 commits)
  mptcp: fix duplicate data handling
  mptcp: fix bad RCVPRUNED mib accounting
  ipv6: fix ndisc_is_useropt() handling for PIO
  igc: Fix double reset adapter triggered from a single taprio cmd
  net: MAINTAINERS: Demote Qualcomm IPA to "maintained"
  net: wan: fsl_qmc_hdlc: Discard received CRC
  net: wan: fsl_qmc_hdlc: Convert carrier_lock spinlock to a mutex
  net/mlx5e: Add a check for the return value from mlx5_port_set_eth_ptys
  net/mlx5e: Fix CT entry update leaks of modify header context
  net/mlx5e: Require mlx5 tc classifier action support for IPsec prio capability
  net/mlx5: Fix missing lock on sync reset reload
  net/mlx5: Lag, don't use the hardcoded value of the first port
  net/mlx5: DR, Fix 'stack guard page was hit' error in dr_rule
  net/mlx5: Fix error handling in irq_pool_request_irq
  net/mlx5: Always drain health in shutdown callback
  net: Add skbuff.h to MAINTAINERS
  r8169: don't increment tx_dropped in case of NETDEV_TX_BUSY
  netfilter: iptables: Fix potential null-ptr-deref in ip6table_nat_table_init().
  netfilter: iptables: Fix null-ptr-deref in iptable_nat_table_init().
  net: drop bad gso csum_start and offset in virtio_net_hdr
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>netfilter: iptables: Fix null-ptr-deref in iptable_nat_table_init().</title>
<updated>2024-07-31T21:20:50+00:00</updated>
<author>
<name>Kuniyuki Iwashima</name>
<email>kuniyu@amazon.com</email>
</author>
<published>2024-07-25T19:28:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5830aa863981d43560748aa93589c0695191d95d'/>
<id>5830aa863981d43560748aa93589c0695191d95d</id>
<content type='text'>
We had a report that iptables-restore sometimes triggered null-ptr-deref
at boot time. [0]

The problem is that iptable_nat_table_init() is exposed to user space
before the kernel fully initialises netns.

In the small race window, a user could call iptable_nat_table_init()
that accesses net_generic(net, iptable_nat_net_id), which is available
only after registering iptable_nat_net_ops.

Let's call register_pernet_subsys() before xt_register_template().

[0]:
bpfilter: Loaded bpfilter_umh pid 11702
Started bpfilter
BUG: kernel NULL pointer dereference, address: 0000000000000013
 PF: supervisor write access in kernel mode
 PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
PREEMPT SMP NOPTI
CPU: 2 PID: 11879 Comm: iptables-restor Not tainted 6.1.92-99.174.amzn2023.x86_64 #1
Hardware name: Amazon EC2 c6i.4xlarge/, BIOS 1.0 10/16/2017
RIP: 0010:iptable_nat_table_init (net/ipv4/netfilter/iptable_nat.c:87 net/ipv4/netfilter/iptable_nat.c:121) iptable_nat
Code: 10 4c 89 f6 48 89 ef e8 0b 19 bb ff 41 89 c4 85 c0 75 38 41 83 c7 01 49 83 c6 28 41 83 ff 04 75 dc 48 8b 44 24 08 48 8b 0c 24 &lt;48&gt; 89 08 4c 89 ef e8 a2 3b a2 cf 48 83 c4 10 44 89 e0 5b 5d 41 5c
RSP: 0018:ffffbef902843cd0 EFLAGS: 00010246
RAX: 0000000000000013 RBX: ffff9f4b052caa20 RCX: ffff9f4b20988d80
RDX: 0000000000000000 RSI: 0000000000000064 RDI: ffffffffc04201c0
RBP: ffff9f4b29394000 R08: ffff9f4b07f77258 R09: ffff9f4b07f77240
R10: 0000000000000000 R11: ffff9f4b09635388 R12: 0000000000000000
R13: ffff9f4b1a3c6c00 R14: ffff9f4b20988e20 R15: 0000000000000004
FS:  00007f6284340000(0000) GS:ffff9f51fe280000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000013 CR3: 00000001d10a6005 CR4: 00000000007706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 &lt;TASK&gt;
 ? show_trace_log_lvl (arch/x86/kernel/dumpstack.c:259)
 ? show_trace_log_lvl (arch/x86/kernel/dumpstack.c:259)
 ? xt_find_table_lock (net/netfilter/x_tables.c:1259)
 ? __die_body.cold (arch/x86/kernel/dumpstack.c:478 arch/x86/kernel/dumpstack.c:420)
 ? page_fault_oops (arch/x86/mm/fault.c:727)
 ? exc_page_fault (./arch/x86/include/asm/irqflags.h:40 ./arch/x86/include/asm/irqflags.h:75 arch/x86/mm/fault.c:1470 arch/x86/mm/fault.c:1518)
 ? asm_exc_page_fault (./arch/x86/include/asm/idtentry.h:570)
 ? iptable_nat_table_init (net/ipv4/netfilter/iptable_nat.c:87 net/ipv4/netfilter/iptable_nat.c:121) iptable_nat
 xt_find_table_lock (net/netfilter/x_tables.c:1259)
 xt_request_find_table_lock (net/netfilter/x_tables.c:1287)
 get_info (net/ipv4/netfilter/ip_tables.c:965)
 ? security_capable (security/security.c:809 (discriminator 13))
 ? ns_capable (kernel/capability.c:376 kernel/capability.c:397)
 ? do_ipt_get_ctl (net/ipv4/netfilter/ip_tables.c:1656)
 ? bpfilter_send_req (net/bpfilter/bpfilter_kern.c:52) bpfilter
 nf_getsockopt (net/netfilter/nf_sockopt.c:116)
 ip_getsockopt (net/ipv4/ip_sockglue.c:1827)
 __sys_getsockopt (net/socket.c:2327)
 __x64_sys_getsockopt (net/socket.c:2342 net/socket.c:2339 net/socket.c:2339)
 do_syscall_64 (arch/x86/entry/common.c:51 arch/x86/entry/common.c:81)
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
RIP: 0033:0x7f62844685ee
Code: 48 8b 0d 45 28 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 37 00 00 00 0f 05 &lt;48&gt; 3d 00 f0 ff ff 77 0a c3 66 0f 1f 84 00 00 00 00 00 48 8b 15 09
RSP: 002b:00007ffd1f83d638 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007ffd1f83d680 RCX: 00007f62844685ee
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000004 R08: 00007ffd1f83d670 R09: 0000558798ffa2a0
R10: 00007ffd1f83d680 R11: 0000000000000246 R12: 00007ffd1f83e3b2
R13: 00007f628455baa0 R14: 00007ffd1f83d7b0 R15: 00007f628457a008
 &lt;/TASK&gt;
Modules linked in: iptable_nat(+) bpfilter rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache veth xt_state xt_connmark xt_nat xt_statistic xt_MASQUERADE xt_mark xt_addrtype ipt_REJECT nf_reject_ipv4 nft_chain_nat nf_nat xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xt_comment nft_compat nf_tables nfnetlink overlay nls_ascii nls_cp437 vfat fat ghash_clmulni_intel aesni_intel ena crypto_simd ptp cryptd i8042 pps_core serio button sunrpc sch_fq_codel configfs loop dm_mod fuse dax dmi_sysfs crc32_pclmul crc32c_intel efivarfs
CR2: 0000000000000013

Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default")
Reported-by: Takahiro Kawahara &lt;takawaha@amazon.co.jp&gt;
Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Reviewed-by: Florian Westphal &lt;fw@strlen.de&gt;
Signed-off-by: Pablo Neira Ayuso &lt;pablo@netfilter.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We had a report that iptables-restore sometimes triggered null-ptr-deref
at boot time. [0]

The problem is that iptable_nat_table_init() is exposed to user space
before the kernel fully initialises netns.

In the small race window, a user could call iptable_nat_table_init()
that accesses net_generic(net, iptable_nat_net_id), which is available
only after registering iptable_nat_net_ops.

Let's call register_pernet_subsys() before xt_register_template().

[0]:
bpfilter: Loaded bpfilter_umh pid 11702
Started bpfilter
BUG: kernel NULL pointer dereference, address: 0000000000000013
 PF: supervisor write access in kernel mode
 PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
PREEMPT SMP NOPTI
CPU: 2 PID: 11879 Comm: iptables-restor Not tainted 6.1.92-99.174.amzn2023.x86_64 #1
Hardware name: Amazon EC2 c6i.4xlarge/, BIOS 1.0 10/16/2017
RIP: 0010:iptable_nat_table_init (net/ipv4/netfilter/iptable_nat.c:87 net/ipv4/netfilter/iptable_nat.c:121) iptable_nat
Code: 10 4c 89 f6 48 89 ef e8 0b 19 bb ff 41 89 c4 85 c0 75 38 41 83 c7 01 49 83 c6 28 41 83 ff 04 75 dc 48 8b 44 24 08 48 8b 0c 24 &lt;48&gt; 89 08 4c 89 ef e8 a2 3b a2 cf 48 83 c4 10 44 89 e0 5b 5d 41 5c
RSP: 0018:ffffbef902843cd0 EFLAGS: 00010246
RAX: 0000000000000013 RBX: ffff9f4b052caa20 RCX: ffff9f4b20988d80
RDX: 0000000000000000 RSI: 0000000000000064 RDI: ffffffffc04201c0
RBP: ffff9f4b29394000 R08: ffff9f4b07f77258 R09: ffff9f4b07f77240
R10: 0000000000000000 R11: ffff9f4b09635388 R12: 0000000000000000
R13: ffff9f4b1a3c6c00 R14: ffff9f4b20988e20 R15: 0000000000000004
FS:  00007f6284340000(0000) GS:ffff9f51fe280000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000013 CR3: 00000001d10a6005 CR4: 00000000007706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 &lt;TASK&gt;
 ? show_trace_log_lvl (arch/x86/kernel/dumpstack.c:259)
 ? show_trace_log_lvl (arch/x86/kernel/dumpstack.c:259)
 ? xt_find_table_lock (net/netfilter/x_tables.c:1259)
 ? __die_body.cold (arch/x86/kernel/dumpstack.c:478 arch/x86/kernel/dumpstack.c:420)
 ? page_fault_oops (arch/x86/mm/fault.c:727)
 ? exc_page_fault (./arch/x86/include/asm/irqflags.h:40 ./arch/x86/include/asm/irqflags.h:75 arch/x86/mm/fault.c:1470 arch/x86/mm/fault.c:1518)
 ? asm_exc_page_fault (./arch/x86/include/asm/idtentry.h:570)
 ? iptable_nat_table_init (net/ipv4/netfilter/iptable_nat.c:87 net/ipv4/netfilter/iptable_nat.c:121) iptable_nat
 xt_find_table_lock (net/netfilter/x_tables.c:1259)
 xt_request_find_table_lock (net/netfilter/x_tables.c:1287)
 get_info (net/ipv4/netfilter/ip_tables.c:965)
 ? security_capable (security/security.c:809 (discriminator 13))
 ? ns_capable (kernel/capability.c:376 kernel/capability.c:397)
 ? do_ipt_get_ctl (net/ipv4/netfilter/ip_tables.c:1656)
 ? bpfilter_send_req (net/bpfilter/bpfilter_kern.c:52) bpfilter
 nf_getsockopt (net/netfilter/nf_sockopt.c:116)
 ip_getsockopt (net/ipv4/ip_sockglue.c:1827)
 __sys_getsockopt (net/socket.c:2327)
 __x64_sys_getsockopt (net/socket.c:2342 net/socket.c:2339 net/socket.c:2339)
 do_syscall_64 (arch/x86/entry/common.c:51 arch/x86/entry/common.c:81)
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
RIP: 0033:0x7f62844685ee
Code: 48 8b 0d 45 28 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 37 00 00 00 0f 05 &lt;48&gt; 3d 00 f0 ff ff 77 0a c3 66 0f 1f 84 00 00 00 00 00 48 8b 15 09
RSP: 002b:00007ffd1f83d638 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007ffd1f83d680 RCX: 00007f62844685ee
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000004 R08: 00007ffd1f83d670 R09: 0000558798ffa2a0
R10: 00007ffd1f83d680 R11: 0000000000000246 R12: 00007ffd1f83e3b2
R13: 00007f628455baa0 R14: 00007ffd1f83d7b0 R15: 00007f628457a008
 &lt;/TASK&gt;
Modules linked in: iptable_nat(+) bpfilter rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache veth xt_state xt_connmark xt_nat xt_statistic xt_MASQUERADE xt_mark xt_addrtype ipt_REJECT nf_reject_ipv4 nft_chain_nat nf_nat xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xt_comment nft_compat nf_tables nfnetlink overlay nls_ascii nls_cp437 vfat fat ghash_clmulni_intel aesni_intel ena crypto_simd ptp cryptd i8042 pps_core serio button sunrpc sch_fq_codel configfs loop dm_mod fuse dax dmi_sysfs crc32_pclmul crc32c_intel efivarfs
CR2: 0000000000000013

Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default")
Reported-by: Takahiro Kawahara &lt;takawaha@amazon.co.jp&gt;
Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Reviewed-by: Florian Westphal &lt;fw@strlen.de&gt;
Signed-off-by: Pablo Neira Ayuso &lt;pablo@netfilter.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: drop bad gso csum_start and offset in virtio_net_hdr</title>
<updated>2024-07-31T01:34:13+00:00</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2024-07-29T20:10:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=89add40066f9ed9abe5f7f886fe5789ff7e0c50e'/>
<id>89add40066f9ed9abe5f7f886fe5789ff7e0c50e</id>
<content type='text'>
Tighten csum_start and csum_offset checks in virtio_net_hdr_to_skb
for GSO packets.

The function already checks that a checksum requested with
VIRTIO_NET_HDR_F_NEEDS_CSUM is in skb linear. But for GSO packets
this might not hold for segs after segmentation.

Syzkaller demonstrated to reach this warning in skb_checksum_help

	offset = skb_checksum_start_offset(skb);
	ret = -EINVAL;
	if (WARN_ON_ONCE(offset &gt;= skb_headlen(skb)))

By injecting a TSO packet:

WARNING: CPU: 1 PID: 3539 at net/core/dev.c:3284 skb_checksum_help+0x3d0/0x5b0
 ip_do_fragment+0x209/0x1b20 net/ipv4/ip_output.c:774
 ip_finish_output_gso net/ipv4/ip_output.c:279 [inline]
 __ip_finish_output+0x2bd/0x4b0 net/ipv4/ip_output.c:301
 iptunnel_xmit+0x50c/0x930 net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x2296/0x2c70 net/ipv4/ip_tunnel.c:813
 __gre_xmit net/ipv4/ip_gre.c:469 [inline]
 ipgre_xmit+0x759/0xa60 net/ipv4/ip_gre.c:661
 __netdev_start_xmit include/linux/netdevice.h:4850 [inline]
 netdev_start_xmit include/linux/netdevice.h:4864 [inline]
 xmit_one net/core/dev.c:3595 [inline]
 dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3611
 __dev_queue_xmit+0x1b97/0x3c90 net/core/dev.c:4261
 packet_snd net/packet/af_packet.c:3073 [inline]

The geometry of the bad input packet at tcp_gso_segment:

[   52.003050][ T8403] skb len=12202 headroom=244 headlen=12093 tailroom=0
[   52.003050][ T8403] mac=(168,24) mac_len=24 net=(192,52) trans=244
[   52.003050][ T8403] shinfo(txflags=0 nr_frags=1 gso(size=1552 type=3 segs=0))
[   52.003050][ T8403] csum(0x60000c7 start=199 offset=1536
ip_summed=3 complete_sw=0 valid=0 level=0)

Mitigate with stricter input validation.

csum_offset: for GSO packets, deduce the correct value from gso_type.
This is already done for USO. Extend it to TSO. Let UFO be:
udp[46]_ufo_fragment ignores these fields and always computes the
checksum in software.

csum_start: finding the real offset requires parsing to the transport
header. Do not add a parser, use existing segmentation parsing. Thanks
to SKB_GSO_DODGY, that also catches bad packets that are hw offloaded.
Again test both TSO and USO. Do not test UFO for the above reason, and
do not test UDP tunnel offload.

GSO packet are almost always CHECKSUM_PARTIAL. USO packets may be
CHECKSUM_NONE since commit 10154dbded6d6 ("udp: Allow GSO transmit
from devices with no checksum offload"), but then still these fields
are initialized correctly in udp4_hwcsum/udp6_hwcsum_outgoing. So no
need to test for ip_summed == CHECKSUM_PARTIAL first.

This revises an existing fix mentioned in the Fixes tag, which broke
small packets with GSO offload, as detected by kselftests.

Link: https://syzkaller.appspot.com/bug?extid=e1db31216c789f552871
Link: https://lore.kernel.org/netdev/20240723223109.2196886-1-kuba@kernel.org
Fixes: e269d79c7d35 ("net: missing check virtio")
Cc: stable@vger.kernel.org
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Link: https://patch.msgid.link/20240729201108.1615114-1-willemdebruijn.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>
Tighten csum_start and csum_offset checks in virtio_net_hdr_to_skb
for GSO packets.

The function already checks that a checksum requested with
VIRTIO_NET_HDR_F_NEEDS_CSUM is in skb linear. But for GSO packets
this might not hold for segs after segmentation.

Syzkaller demonstrated to reach this warning in skb_checksum_help

	offset = skb_checksum_start_offset(skb);
	ret = -EINVAL;
	if (WARN_ON_ONCE(offset &gt;= skb_headlen(skb)))

By injecting a TSO packet:

WARNING: CPU: 1 PID: 3539 at net/core/dev.c:3284 skb_checksum_help+0x3d0/0x5b0
 ip_do_fragment+0x209/0x1b20 net/ipv4/ip_output.c:774
 ip_finish_output_gso net/ipv4/ip_output.c:279 [inline]
 __ip_finish_output+0x2bd/0x4b0 net/ipv4/ip_output.c:301
 iptunnel_xmit+0x50c/0x930 net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x2296/0x2c70 net/ipv4/ip_tunnel.c:813
 __gre_xmit net/ipv4/ip_gre.c:469 [inline]
 ipgre_xmit+0x759/0xa60 net/ipv4/ip_gre.c:661
 __netdev_start_xmit include/linux/netdevice.h:4850 [inline]
 netdev_start_xmit include/linux/netdevice.h:4864 [inline]
 xmit_one net/core/dev.c:3595 [inline]
 dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3611
 __dev_queue_xmit+0x1b97/0x3c90 net/core/dev.c:4261
 packet_snd net/packet/af_packet.c:3073 [inline]

The geometry of the bad input packet at tcp_gso_segment:

[   52.003050][ T8403] skb len=12202 headroom=244 headlen=12093 tailroom=0
[   52.003050][ T8403] mac=(168,24) mac_len=24 net=(192,52) trans=244
[   52.003050][ T8403] shinfo(txflags=0 nr_frags=1 gso(size=1552 type=3 segs=0))
[   52.003050][ T8403] csum(0x60000c7 start=199 offset=1536
ip_summed=3 complete_sw=0 valid=0 level=0)

Mitigate with stricter input validation.

csum_offset: for GSO packets, deduce the correct value from gso_type.
This is already done for USO. Extend it to TSO. Let UFO be:
udp[46]_ufo_fragment ignores these fields and always computes the
checksum in software.

csum_start: finding the real offset requires parsing to the transport
header. Do not add a parser, use existing segmentation parsing. Thanks
to SKB_GSO_DODGY, that also catches bad packets that are hw offloaded.
Again test both TSO and USO. Do not test UFO for the above reason, and
do not test UDP tunnel offload.

GSO packet are almost always CHECKSUM_PARTIAL. USO packets may be
CHECKSUM_NONE since commit 10154dbded6d6 ("udp: Allow GSO transmit
from devices with no checksum offload"), but then still these fields
are initialized correctly in udp4_hwcsum/udp6_hwcsum_outgoing. So no
need to test for ip_summed == CHECKSUM_PARTIAL first.

This revises an existing fix mentioned in the Fixes tag, which broke
small packets with GSO offload, as detected by kselftests.

Link: https://syzkaller.appspot.com/bug?extid=e1db31216c789f552871
Link: https://lore.kernel.org/netdev/20240723223109.2196886-1-kuba@kernel.org
Fixes: e269d79c7d35 ("net: missing check virtio")
Cc: stable@vger.kernel.org
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Link: https://patch.msgid.link/20240729201108.1615114-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: Adjust clamping window for applications specifying SO_RCVBUF</title>
<updated>2024-07-29T10:31:50+00:00</updated>
<author>
<name>Subash Abhinov Kasiviswanathan</name>
<email>quic_subashab@quicinc.com</email>
</author>
<published>2024-07-26T20:41:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=05f76b2d634e65ab34472802d9b142ea9e03f74e'/>
<id>05f76b2d634e65ab34472802d9b142ea9e03f74e</id>
<content type='text'>
tp-&gt;scaling_ratio is not updated based on skb-&gt;len/skb-&gt;truesize once
SO_RCVBUF is set leading to the maximum window scaling to be 25% of
rcvbuf after
commit dfa2f0483360 ("tcp: get rid of sysctl_tcp_adv_win_scale")
and 50% of rcvbuf after
commit 697a6c8cec03 ("tcp: increase the default TCP scaling ratio").
50% tries to emulate the behavior of older kernels using
sysctl_tcp_adv_win_scale with default value.

Systems which were using a different values of sysctl_tcp_adv_win_scale
in older kernels ended up seeing reduced download speeds in certain
cases as covered in https://lists.openwall.net/netdev/2024/05/15/13
While the sysctl scheme is no longer acceptable, the value of 50% is
a bit conservative when the skb-&gt;len/skb-&gt;truesize ratio is later
determined to be ~0.66.

Applications not specifying SO_RCVBUF update the window scaling and
the receiver buffer every time data is copied to userspace. This
computation is now used for applications setting SO_RCVBUF to update
the maximum window scaling while ensuring that the receive buffer
is within the application specified limit.

Fixes: dfa2f0483360 ("tcp: get rid of sysctl_tcp_adv_win_scale")
Signed-off-by: Sean Tranchetti &lt;quic_stranche@quicinc.com&gt;
Signed-off-by: Subash Abhinov Kasiviswanathan &lt;quic_subashab@quicinc.com&gt;
Reviewed-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>
tp-&gt;scaling_ratio is not updated based on skb-&gt;len/skb-&gt;truesize once
SO_RCVBUF is set leading to the maximum window scaling to be 25% of
rcvbuf after
commit dfa2f0483360 ("tcp: get rid of sysctl_tcp_adv_win_scale")
and 50% of rcvbuf after
commit 697a6c8cec03 ("tcp: increase the default TCP scaling ratio").
50% tries to emulate the behavior of older kernels using
sysctl_tcp_adv_win_scale with default value.

Systems which were using a different values of sysctl_tcp_adv_win_scale
in older kernels ended up seeing reduced download speeds in certain
cases as covered in https://lists.openwall.net/netdev/2024/05/15/13
While the sysctl scheme is no longer acceptable, the value of 50% is
a bit conservative when the skb-&gt;len/skb-&gt;truesize ratio is later
determined to be ~0.66.

Applications not specifying SO_RCVBUF update the window scaling and
the receiver buffer every time data is copied to userspace. This
computation is now used for applications setting SO_RCVBUF to update
the maximum window scaling while ensuring that the receive buffer
is within the application specified limit.

Fixes: dfa2f0483360 ("tcp: get rid of sysctl_tcp_adv_win_scale")
Signed-off-by: Sean Tranchetti &lt;quic_stranche@quicinc.com&gt;
Signed-off-by: Subash Abhinov Kasiviswanathan &lt;quic_subashab@quicinc.com&gt;
Reviewed-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>minmax: add a few more MIN_T/MAX_T users</title>
<updated>2024-07-28T20:41:14+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-07-28T20:03:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=4477b39c32fdc03363affef4b11d48391e6dc9ff'/>
<id>4477b39c32fdc03363affef4b11d48391e6dc9ff</id>
<content type='text'>
Commit 3a7e02c040b1 ("minmax: avoid overly complicated constant
expressions in VM code") added the simpler MIN_T/MAX_T macros in order
to avoid some excessive expansion from the rather complicated regular
min/max macros.

The complexity of those macros stems from two issues:

 (a) trying to use them in situations that require a C constant
     expression (in static initializers and for array sizes)

 (b) the type sanity checking

and MIN_T/MAX_T avoids both of these issues.

Now, in the whole (long) discussion about all this, it was pointed out
that the whole type sanity checking is entirely unnecessary for
min_t/max_t which get a fixed type that the comparison is done in.

But that still leaves min_t/max_t unnecessarily complicated due to
worries about the C constant expression case.

However, it turns out that there really aren't very many cases that use
min_t/max_t for this, and we can just force-convert those.

This does exactly that.

Which in turn will then allow for much simpler implementations of
min_t()/max_t().  All the usual "macros in all upper case will evaluate
the arguments multiple times" rules apply.

We should do all the same things for the regular min/max() vs MIN/MAX()
cases, but that has the added complexity of various drivers defining
their own local versions of MIN/MAX, so that needs another level of
fixes first.

Link: https://lore.kernel.org/all/b47fad1d0cf8449886ad148f8c013dae@AcuMS.aculab.com/
Cc: David Laight &lt;David.Laight@aculab.com&gt;
Cc: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit 3a7e02c040b1 ("minmax: avoid overly complicated constant
expressions in VM code") added the simpler MIN_T/MAX_T macros in order
to avoid some excessive expansion from the rather complicated regular
min/max macros.

The complexity of those macros stems from two issues:

 (a) trying to use them in situations that require a C constant
     expression (in static initializers and for array sizes)

 (b) the type sanity checking

and MIN_T/MAX_T avoids both of these issues.

Now, in the whole (long) discussion about all this, it was pointed out
that the whole type sanity checking is entirely unnecessary for
min_t/max_t which get a fixed type that the comparison is done in.

But that still leaves min_t/max_t unnecessarily complicated due to
worries about the C constant expression case.

However, it turns out that there really aren't very many cases that use
min_t/max_t for this, and we can just force-convert those.

This does exactly that.

Which in turn will then allow for much simpler implementations of
min_t()/max_t().  All the usual "macros in all upper case will evaluate
the arguments multiple times" rules apply.

We should do all the same things for the regular min/max() vs MIN/MAX()
cases, but that has the added complexity of various drivers defining
their own local versions of MIN/MAX, so that needs another level of
fixes first.

Link: https://lore.kernel.org/all/b47fad1d0cf8449886ad148f8c013dae@AcuMS.aculab.com/
Cc: David Laight &lt;David.Laight@aculab.com&gt;
Cc: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'net-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net</title>
<updated>2024-07-25T20:32:25+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-07-25T20:32:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1722389b0d863056d78287a120a1d6cadb8d4f7b'/>
<id>1722389b0d863056d78287a120a1d6cadb8d4f7b</id>
<content type='text'>
Pull networking fixes from Jakub Kicinski:
 "Including fixes from bpf and netfilter.

  A lot of networking people were at a conference last week, busy
  catching COVID, so relatively short PR.

  Current release - regressions:

   - tcp: process the 3rd ACK with sk_socket for TFO and MPTCP

  Current release - new code bugs:

   - l2tp: protect session IDR and tunnel session list with one lock,
     make sure the state is coherent to avoid a warning

   - eth: bnxt_en: update xdp_rxq_info in queue restart logic

   - eth: airoha: fix location of the MBI_RX_AGE_SEL_MASK field

  Previous releases - regressions:

   - xsk: require XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len,
     the field reuses previously un-validated pad

  Previous releases - always broken:

   - tap/tun: drop short frames to prevent crashes later in the stack

   - eth: ice: add a per-VF limit on number of FDIR filters

   - af_unix: disable MSG_OOB handling for sockets in sockmap/sockhash"

* tag 'net-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (34 commits)
  tun: add missing verification for short frame
  tap: add missing verification for short frame
  mISDN: Fix a use after free in hfcmulti_tx()
  gve: Fix an edge case for TSO skb validity check
  bnxt_en: update xdp_rxq_info in queue restart logic
  tcp: process the 3rd ACK with sk_socket for TFO/MPTCP
  selftests/bpf: Add XDP_UMEM_TX_METADATA_LEN to XSK TX metadata test
  xsk: Require XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len
  bpf: Fix a segment issue when downgrading gso_size
  net: mediatek: Fix potential NULL pointer dereference in dummy net_device handling
  MAINTAINERS: make Breno the netconsole maintainer
  MAINTAINERS: Update bonding entry
  net: nexthop: Initialize all fields in dumped nexthops
  net: stmmac: Correct byte order of perfect_match
  selftests: forwarding: skip if kernel not support setting bridge fdb learning limit
  tipc: Return non-zero value from tipc_udp_addr2str() on error
  netfilter: nft_set_pipapo_avx2: disable softinterrupts
  ice: Fix recipe read procedure
  ice: Add a per-VF limit on number of FDIR filters
  net: bonding: correctly annotate RCU in bond_should_notify_peers()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull networking fixes from Jakub Kicinski:
 "Including fixes from bpf and netfilter.

  A lot of networking people were at a conference last week, busy
  catching COVID, so relatively short PR.

  Current release - regressions:

   - tcp: process the 3rd ACK with sk_socket for TFO and MPTCP

  Current release - new code bugs:

   - l2tp: protect session IDR and tunnel session list with one lock,
     make sure the state is coherent to avoid a warning

   - eth: bnxt_en: update xdp_rxq_info in queue restart logic

   - eth: airoha: fix location of the MBI_RX_AGE_SEL_MASK field

  Previous releases - regressions:

   - xsk: require XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len,
     the field reuses previously un-validated pad

  Previous releases - always broken:

   - tap/tun: drop short frames to prevent crashes later in the stack

   - eth: ice: add a per-VF limit on number of FDIR filters

   - af_unix: disable MSG_OOB handling for sockets in sockmap/sockhash"

* tag 'net-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (34 commits)
  tun: add missing verification for short frame
  tap: add missing verification for short frame
  mISDN: Fix a use after free in hfcmulti_tx()
  gve: Fix an edge case for TSO skb validity check
  bnxt_en: update xdp_rxq_info in queue restart logic
  tcp: process the 3rd ACK with sk_socket for TFO/MPTCP
  selftests/bpf: Add XDP_UMEM_TX_METADATA_LEN to XSK TX metadata test
  xsk: Require XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len
  bpf: Fix a segment issue when downgrading gso_size
  net: mediatek: Fix potential NULL pointer dereference in dummy net_device handling
  MAINTAINERS: make Breno the netconsole maintainer
  MAINTAINERS: Update bonding entry
  net: nexthop: Initialize all fields in dumped nexthops
  net: stmmac: Correct byte order of perfect_match
  selftests: forwarding: skip if kernel not support setting bridge fdb learning limit
  tipc: Return non-zero value from tipc_udp_addr2str() on error
  netfilter: nft_set_pipapo_avx2: disable softinterrupts
  ice: Fix recipe read procedure
  ice: Add a per-VF limit on number of FDIR filters
  net: bonding: correctly annotate RCU in bond_should_notify_peers()
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>tcp: process the 3rd ACK with sk_socket for TFO/MPTCP</title>
<updated>2024-07-25T10:58:19+00:00</updated>
<author>
<name>Matthieu Baerts (NGI0)</name>
<email>matttbe@kernel.org</email>
</author>
<published>2024-07-24T10:25:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c1668292689ad2ee16c9c1750a8044b0b0aad663'/>
<id>c1668292689ad2ee16c9c1750a8044b0b0aad663</id>
<content type='text'>
The 'Fixes' commit recently changed the behaviour of TCP by skipping the
processing of the 3rd ACK when a sk-&gt;sk_socket is set. The goal was to
skip tcp_ack_snd_check() in tcp_rcv_state_process() not to send an
unnecessary ACK in case of simultaneous connect(). Unfortunately, that
had an impact on TFO and MPTCP.

I started to look at the impact on MPTCP, because the MPTCP CI found
some issues with the MPTCP Packetdrill tests [1]. Then Paolo Abeni
suggested me to look at the impact on TFO with "plain" TCP.

For MPTCP, when receiving the 3rd ACK of a request adding a new path
(MP_JOIN), sk-&gt;sk_socket will be set, and point to the MPTCP sock that
has been created when the MPTCP connection got established before with
the first path. The newly added 'goto' will then skip the processing of
the segment text (step 7) and not go through tcp_data_queue() where the
MPTCP options are validated, and some actions are triggered, e.g.
sending the MPJ 4th ACK [2] as demonstrated by the new errors when
running a packetdrill test [3] establishing a second subflow.

This doesn't fully break MPTCP, mainly the 4th MPJ ACK that will be
delayed. Still, we don't want to have this behaviour as it delays the
switch to the fully established mode, and invalid MPTCP options in this
3rd ACK will not be caught any more. This modification also affects the
MPTCP + TFO feature as well, and being the reason why the selftests
started to be unstable the last few days [4].

For TFO, the existing 'basic-cookie-not-reqd' test [5] was no longer
passing: if the 3rd ACK contains data, and the connection is accept()ed
before receiving them, these data would no longer be processed, and thus
not ACKed.

One last thing about MPTCP, in case of simultaneous connect(), a
fallback to TCP will be done, which seems fine:

  `../common/defaults.sh`

   0 socket(..., SOCK_STREAM|SOCK_NONBLOCK, IPPROTO_MPTCP) = 3
  +0 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)

  +0 &gt; S  0:0(0)                 &lt;mss 1460, sackOK, TS val 100 ecr 0,   nop, wscale 8, mpcapable v1 flags[flag_h] nokey&gt;
  +0 &lt; S  0:0(0) win 1000        &lt;mss 1460, sackOK, TS val 407 ecr 0,   nop, wscale 8, mpcapable v1 flags[flag_h] nokey&gt;
  +0 &gt; S. 0:0(0) ack 1           &lt;mss 1460, sackOK, TS val 330 ecr 0,   nop, wscale 8, mpcapable v1 flags[flag_h] nokey&gt;
  +0 &lt; S. 0:0(0) ack 1 win 65535 &lt;mss 1460, sackOK, TS val 700 ecr 100, nop, wscale 8, mpcapable v1 flags[flag_h] key[skey=2]&gt;
  +0 &gt;  . 1:1(0) ack 1           &lt;nop, nop, TS val 845707014 ecr 700, nop, nop, sack 0:1&gt;

Simultaneous SYN-data crossing is also not supported by TFO, see [6].

Kuniyuki Iwashima suggested to restrict the processing to SYN+ACK only:
that's a more generic solution than the one initially proposed, and
also enough to fix the issues described above.

Later on, Eric Dumazet mentioned that an ACK should still be sent in
reaction to the second SYN+ACK that is received: not sending a DUPACK
here seems wrong and could hurt:

   0 socket(..., SOCK_STREAM|SOCK_NONBLOCK, IPPROTO_TCP) = 3
  +0 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)

  +0 &gt; S  0:0(0)                &lt;mss 1460, sackOK, TS val 1000 ecr 0,nop,wscale 8&gt;
  +0 &lt; S  0:0(0)       win 1000 &lt;mss 1000, sackOK, nop, nop&gt;
  +0 &gt; S. 0:0(0) ack 1          &lt;mss 1460, sackOK, TS val 3308134035 ecr 0,nop,wscale 8&gt;
  +0 &lt; S. 0:0(0) ack 1 win 1000 &lt;mss 1000, sackOK, nop, nop&gt;
  +0 &gt;  . 1:1(0) ack 1          &lt;nop, nop, sack 0:1&gt;  // &lt;== Here

So in this version, the 'goto consume' is dropped, to always send an ACK
when switching from TCP_SYN_RECV to TCP_ESTABLISHED. This ACK will be
seen as a DUPACK -- with DSACK if SACK has been negotiated -- in case of
simultaneous SYN crossing: that's what is expected here.

Link: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/9936227696 [1]
Link: https://datatracker.ietf.org/doc/html/rfc8684#fig_tokens [2]
Link: https://github.com/multipath-tcp/packetdrill/blob/mptcp-net-next/gtests/net/mptcp/syscalls/accept.pkt#L28 [3]
Link: https://netdev.bots.linux.dev/contest.html?executor=vmksft-mptcp-dbg&amp;test=mptcp-connect-sh [4]
Link: https://github.com/google/packetdrill/blob/master/gtests/net/tcp/fastopen/server/basic-cookie-not-reqd.pkt#L21 [5]
Link: https://github.com/google/packetdrill/blob/master/gtests/net/tcp/fastopen/client/simultaneous-fast-open.pkt [6]
Fixes: 23e89e8ee7be ("tcp: Don't drop SYN+ACK for simultaneous connect().")
Suggested-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
Suggested-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Suggested-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Matthieu Baerts (NGI0) &lt;matttbe@kernel.org&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Link: https://patch.msgid.link/20240724-upstream-net-next-20240716-tcp-3rd-ack-consume-sk_socket-v3-1-d48339764ce9@kernel.org
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The 'Fixes' commit recently changed the behaviour of TCP by skipping the
processing of the 3rd ACK when a sk-&gt;sk_socket is set. The goal was to
skip tcp_ack_snd_check() in tcp_rcv_state_process() not to send an
unnecessary ACK in case of simultaneous connect(). Unfortunately, that
had an impact on TFO and MPTCP.

I started to look at the impact on MPTCP, because the MPTCP CI found
some issues with the MPTCP Packetdrill tests [1]. Then Paolo Abeni
suggested me to look at the impact on TFO with "plain" TCP.

For MPTCP, when receiving the 3rd ACK of a request adding a new path
(MP_JOIN), sk-&gt;sk_socket will be set, and point to the MPTCP sock that
has been created when the MPTCP connection got established before with
the first path. The newly added 'goto' will then skip the processing of
the segment text (step 7) and not go through tcp_data_queue() where the
MPTCP options are validated, and some actions are triggered, e.g.
sending the MPJ 4th ACK [2] as demonstrated by the new errors when
running a packetdrill test [3] establishing a second subflow.

This doesn't fully break MPTCP, mainly the 4th MPJ ACK that will be
delayed. Still, we don't want to have this behaviour as it delays the
switch to the fully established mode, and invalid MPTCP options in this
3rd ACK will not be caught any more. This modification also affects the
MPTCP + TFO feature as well, and being the reason why the selftests
started to be unstable the last few days [4].

For TFO, the existing 'basic-cookie-not-reqd' test [5] was no longer
passing: if the 3rd ACK contains data, and the connection is accept()ed
before receiving them, these data would no longer be processed, and thus
not ACKed.

One last thing about MPTCP, in case of simultaneous connect(), a
fallback to TCP will be done, which seems fine:

  `../common/defaults.sh`

   0 socket(..., SOCK_STREAM|SOCK_NONBLOCK, IPPROTO_MPTCP) = 3
  +0 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)

  +0 &gt; S  0:0(0)                 &lt;mss 1460, sackOK, TS val 100 ecr 0,   nop, wscale 8, mpcapable v1 flags[flag_h] nokey&gt;
  +0 &lt; S  0:0(0) win 1000        &lt;mss 1460, sackOK, TS val 407 ecr 0,   nop, wscale 8, mpcapable v1 flags[flag_h] nokey&gt;
  +0 &gt; S. 0:0(0) ack 1           &lt;mss 1460, sackOK, TS val 330 ecr 0,   nop, wscale 8, mpcapable v1 flags[flag_h] nokey&gt;
  +0 &lt; S. 0:0(0) ack 1 win 65535 &lt;mss 1460, sackOK, TS val 700 ecr 100, nop, wscale 8, mpcapable v1 flags[flag_h] key[skey=2]&gt;
  +0 &gt;  . 1:1(0) ack 1           &lt;nop, nop, TS val 845707014 ecr 700, nop, nop, sack 0:1&gt;

Simultaneous SYN-data crossing is also not supported by TFO, see [6].

Kuniyuki Iwashima suggested to restrict the processing to SYN+ACK only:
that's a more generic solution than the one initially proposed, and
also enough to fix the issues described above.

Later on, Eric Dumazet mentioned that an ACK should still be sent in
reaction to the second SYN+ACK that is received: not sending a DUPACK
here seems wrong and could hurt:

   0 socket(..., SOCK_STREAM|SOCK_NONBLOCK, IPPROTO_TCP) = 3
  +0 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress)

  +0 &gt; S  0:0(0)                &lt;mss 1460, sackOK, TS val 1000 ecr 0,nop,wscale 8&gt;
  +0 &lt; S  0:0(0)       win 1000 &lt;mss 1000, sackOK, nop, nop&gt;
  +0 &gt; S. 0:0(0) ack 1          &lt;mss 1460, sackOK, TS val 3308134035 ecr 0,nop,wscale 8&gt;
  +0 &lt; S. 0:0(0) ack 1 win 1000 &lt;mss 1000, sackOK, nop, nop&gt;
  +0 &gt;  . 1:1(0) ack 1          &lt;nop, nop, sack 0:1&gt;  // &lt;== Here

So in this version, the 'goto consume' is dropped, to always send an ACK
when switching from TCP_SYN_RECV to TCP_ESTABLISHED. This ACK will be
seen as a DUPACK -- with DSACK if SACK has been negotiated -- in case of
simultaneous SYN crossing: that's what is expected here.

Link: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/9936227696 [1]
Link: https://datatracker.ietf.org/doc/html/rfc8684#fig_tokens [2]
Link: https://github.com/multipath-tcp/packetdrill/blob/mptcp-net-next/gtests/net/mptcp/syscalls/accept.pkt#L28 [3]
Link: https://netdev.bots.linux.dev/contest.html?executor=vmksft-mptcp-dbg&amp;test=mptcp-connect-sh [4]
Link: https://github.com/google/packetdrill/blob/master/gtests/net/tcp/fastopen/server/basic-cookie-not-reqd.pkt#L21 [5]
Link: https://github.com/google/packetdrill/blob/master/gtests/net/tcp/fastopen/client/simultaneous-fast-open.pkt [6]
Fixes: 23e89e8ee7be ("tcp: Don't drop SYN+ACK for simultaneous connect().")
Suggested-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
Suggested-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Suggested-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: Matthieu Baerts (NGI0) &lt;matttbe@kernel.org&gt;
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Link: https://patch.msgid.link/20240724-upstream-net-next-20240716-tcp-3rd-ack-consume-sk_socket-v3-1-d48339764ce9@kernel.org
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>sysctl: treewide: constify the ctl_table argument of proc_handlers</title>
<updated>2024-07-24T18:59:29+00:00</updated>
<author>
<name>Joel Granados</name>
<email>j.granados@samsung.com</email>
</author>
<published>2024-07-24T18:59:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=78eb4ea25cd5fdbdae7eb9fdf87b99195ff67508'/>
<id>78eb4ea25cd5fdbdae7eb9fdf87b99195ff67508</id>
<content type='text'>
const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.

This patch has been generated by the following coccinelle script:

```
  virtual patch

  @r1@
  identifier ctl, write, buffer, lenp, ppos;
  identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

  @r2@
  identifier func, ctl, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos)
  { ... }

  @r3@
  identifier func;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int , void *, size_t *, loff_t *);

  @r4@
  identifier func, ctl;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int , void *, size_t *, loff_t *);

  @r5@
  identifier func, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

```

* Code formatting was adjusted in xfs_sysctl.c to comply with code
  conventions. The xfs_stats_clear_proc_handler,
  xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
  adjusted.

* The ctl_table argument in proc_watchdog_common was const qualified.
  This is called from a proc_handler itself and is calling back into
  another proc_handler, making it necessary to change it as part of the
  proc_handler migration.

Co-developed-by: Thomas Weißschuh &lt;linux@weissschuh.net&gt;
Signed-off-by: Thomas Weißschuh &lt;linux@weissschuh.net&gt;
Co-developed-by: Joel Granados &lt;j.granados@samsung.com&gt;
Signed-off-by: Joel Granados &lt;j.granados@samsung.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.

This patch has been generated by the following coccinelle script:

```
  virtual patch

  @r1@
  identifier ctl, write, buffer, lenp, ppos;
  identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

  @r2@
  identifier func, ctl, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos)
  { ... }

  @r3@
  identifier func;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int , void *, size_t *, loff_t *);

  @r4@
  identifier func, ctl;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int , void *, size_t *, loff_t *);

  @r5@
  identifier func, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

```

* Code formatting was adjusted in xfs_sysctl.c to comply with code
  conventions. The xfs_stats_clear_proc_handler,
  xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
  adjusted.

* The ctl_table argument in proc_watchdog_common was const qualified.
  This is called from a proc_handler itself and is calling back into
  another proc_handler, making it necessary to change it as part of the
  proc_handler migration.

Co-developed-by: Thomas Weißschuh &lt;linux@weissschuh.net&gt;
Signed-off-by: Thomas Weißschuh &lt;linux@weissschuh.net&gt;
Co-developed-by: Joel Granados &lt;j.granados@samsung.com&gt;
Signed-off-by: Joel Granados &lt;j.granados@samsung.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: nexthop: Initialize all fields in dumped nexthops</title>
<updated>2024-07-24T14:13:43+00:00</updated>
<author>
<name>Petr Machata</name>
<email>petrm@nvidia.com</email>
</author>
<published>2024-07-23T16:04:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6d745cd0e9720282cd291d36b9db528aea18add2'/>
<id>6d745cd0e9720282cd291d36b9db528aea18add2</id>
<content type='text'>
struct nexthop_grp contains two reserved fields that are not initialized by
nla_put_nh_group(), and carry garbage. This can be observed e.g. with
strace (edited for clarity):

    # ip nexthop add id 1 dev lo
    # ip nexthop add id 101 group 1
    # strace -e recvmsg ip nexthop get id 101
    ...
    recvmsg(... [{nla_len=12, nla_type=NHA_GROUP},
                 [{id=1, weight=0, resvd1=0x69, resvd2=0x67}]] ...) = 52

The fields are reserved and therefore not currently used. But as they are, they
leak kernel memory, and the fact they are not just zero complicates repurposing
of the fields for new ends. Initialize the full structure.

Fixes: 430a049190de ("nexthop: Add support for nexthop groups")
Signed-off-by: Petr Machata &lt;petrm@nvidia.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-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>
struct nexthop_grp contains two reserved fields that are not initialized by
nla_put_nh_group(), and carry garbage. This can be observed e.g. with
strace (edited for clarity):

    # ip nexthop add id 1 dev lo
    # ip nexthop add id 101 group 1
    # strace -e recvmsg ip nexthop get id 101
    ...
    recvmsg(... [{nla_len=12, nla_type=NHA_GROUP},
                 [{id=1, weight=0, resvd1=0x69, resvd2=0x67}]] ...) = 52

The fields are reserved and therefore not currently used. But as they are, they
leak kernel memory, and the fact they are not just zero complicates repurposing
of the fields for new ends. Initialize the full structure.

Fixes: 430a049190de ("nexthop: Add support for nexthop groups")
Signed-off-by: Petr Machata &lt;petrm@nvidia.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-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>ipv4: Fix incorrect source address in Record Route option</title>
<updated>2024-07-23T08:28:16+00:00</updated>
<author>
<name>Ido Schimmel</name>
<email>idosch@nvidia.com</email>
</author>
<published>2024-07-18T12:34:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cc73bbab4b1fb8a4f53a24645871dafa5f81266a'/>
<id>cc73bbab4b1fb8a4f53a24645871dafa5f81266a</id>
<content type='text'>
The Record Route IP option records the addresses of the routers that
routed the packet. In the case of forwarded packets, the kernel performs
a route lookup via fib_lookup() and fills in the preferred source
address of the matched route.

The lookup is performed with the DS field of the forwarded packet, but
using the RT_TOS() macro which only masks one of the two ECN bits. If
the packet is ECT(0) or CE, the matched route might be different than
the route via which the packet was forwarded as the input path masks
both of the ECN bits, resulting in the wrong address being filled in the
Record Route option.

Fix by masking both of the ECN bits.

Fixes: 8e36360ae876 ("ipv4: Remove route key identity dependencies in ip_rt_get_source().")
Signed-off-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-by: Guillaume Nault &lt;gnault@redhat.com&gt;
Link: https://patch.msgid.link/20240718123407.434778-1-idosch@nvidia.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The Record Route IP option records the addresses of the routers that
routed the packet. In the case of forwarded packets, the kernel performs
a route lookup via fib_lookup() and fills in the preferred source
address of the matched route.

The lookup is performed with the DS field of the forwarded packet, but
using the RT_TOS() macro which only masks one of the two ECN bits. If
the packet is ECT(0) or CE, the matched route might be different than
the route via which the packet was forwarded as the input path masks
both of the ECN bits, resulting in the wrong address being filled in the
Record Route option.

Fix by masking both of the ECN bits.

Fixes: 8e36360ae876 ("ipv4: Remove route key identity dependencies in ip_rt_get_source().")
Signed-off-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-by: Guillaume Nault &lt;gnault@redhat.com&gt;
Link: https://patch.msgid.link/20240718123407.434778-1-idosch@nvidia.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;

</pre>
</div>
</content>
</entry>
</feed>
