| 0/0 |
2026/06/01 23:28 |
flow |
assessment-security |
1h04m
Results: map[DenialOfService:true Explanation:The bug is a stack overflow caused by an infinite recursion loop in the network
stack involving `ipvlan` and `ipvs` (IP Virtual Server).
### Root Cause Analysis
When a packet is transmitted through an `ipvlan` device configured in L3 mode,
the driver calls `ipvlan_xmit_mode_l3()`, which in turn calls
`ipvlan_skb_crossing_ns()`. This function scrubs the socket buffer (`skb`) by
calling `skb_scrub_packet()`, which clears various state flags, including the
`skb->ipvs_property` flag via `ipvs_reset(skb)`.
After scrubbing, the packet is routed and passed to `ip_local_out()`, which
triggers the `NF_INET_LOCAL_OUT` netfilter hooks. IPVS registers its
`ip_vs_in_hook()` at this exact hook. Normally, IPVS avoids processing the same
packet multiple times by checking if `skb->ipvs_property` is set. However,
because `ipvlan` just cleared this flag, IPVS fails to recognize that the packet
was already processed and processes it again.
If the packet matches an IPVS service configured in Direct Routing (DR) mode,
IPVS will route the packet to its destination (`ip_vs_dr_xmit()`). If the
routing table directs the packet back to the same `ipvlan` device, the packet is
queued to the `ipvlan` device again via `dev_queue_xmit()`.
This creates an infinite recursion loop:
`ipvlan_start_xmit` -> `ipvlan_xmit_mode_l3` -> `ip_local_out` ->
`ip_vs_in_hook` -> `ip_vs_dr_xmit` -> `dev_queue_xmit` -> `ipvlan_start_xmit`
...
The recursion continues until the kernel stack overflows and hits the stack
guard page, resulting in a kernel panic.
### Security Impact
* **Exploitable:** **False**. The stack overflow deterministically hits the 4KB
stack guard page (as seen in the `Oops: stack guard page` report). The guard
page triggers a page fault and halts the kernel before any adjacent memory can
be corrupted, preventing privilege escalation or arbitrary code execution.
* **Denial Of Service:** **True**. The bug reliably causes a kernel panic,
leading to a complete system crash.
* **Accessible From Unprivileged Processes:** **False**. Setting up the required
`ipvlan` device and IPVS rules requires `CAP_NET_ADMIN` privileges in the
network namespace.
* **Accessible From User Namespaces:** **True**. Both `ipvlan` devices (e.g., on
top of a `dummy` device) and IPVS can be fully configured inside an unprivileged
user namespace. A local attacker can create a new user/network namespace,
acquire `CAP_NET_ADMIN`, set up the looping configuration, and send a single
packet to crash the host system.
* **Network / Remote Triggers:** **False**. Triggering the bug remotely would
require the target system to already have this specific, self-looping
misconfiguration set up by an administrator. Since this configuration inherently
breaks networking for the involved IPs and serves no legitimate purpose, it is
not a realistic remote attack vector. Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:false UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
|
| 1/1 |
2026/06/01 23:28 |
action |
syz-repro-to-c-repro |
0m
Results:
|
| 2/1 |
2026/06/01 23:28 |
action |
kernel-checkouter |
2m
Results: map[KernelSrc:/app/workdir/cache/src/aa49638edc0e1146026b9d949218a2c9eba72703]
|
| 3/1 |
2026/06/01 23:31 |
action |
kernel-builder |
34m
Results: map[KernelObj:/app/workdir/cache/build/75dff9ab8b01ce119867d019cec7e4feb8c0825b]
|
| 4/1 |
2026/06/02 00:06 |
action |
codesearch-prepare |
24m
Results: map[Index:codesearch-index]
|
| 5/1 |
2026/06/02 00:31 |
agent |
expert |
2m
Model:
Results: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:false UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
Instruction: You are an experienced Linux kernel security engineer. Your task is to analyze given kernel bug report
and determine its security impact based on the following dimensions.
Use the provided tools to examine the source code, check for capability checks (e.g., capable(), ns_capable()),
and understand the nature of the bug. Analyze the given kernel build and configuration.
You can check the kernel config by grepping ".config" file; you can check kernel cmdline by grepping
".config" file for "CONFIG_CMDLINE=". Assume sysctl parameters have default values.
But analyze for the corresponding production build w/o debugging tools enabled (like KASAN, KMSAN, UBSAN).
Try different strategies when analyzing the bug:
- think of ways in which the vulnerable code is unreachable
- or the other way around: try to come up with different ideas of how an unprivileged user can reach the bug
If still unsure err on the side of the bug being non-exploitable/not-accessible.
In the final reply, provide a reasoning for your assessment.
Analysis dimensions:
* Exploitable:
Determine if the bug can result in memory corruption or elevated privileges.
Memory safety issues are almost always exploitable (KASAN or UBSAN reports for use-after-free, out-of-bounds;
refcounting issues, corrupted lists, etc). When kernel is crashing on a completely wild pointer access
(e.g. user-space address, or non-canonical address, but not on NULL or address corresponding to KASAN shadow
for NULL address), including both data accesses and control transfers, that also usually implies possibility
of exploitation. Such reports usually say "unable to handle kernel paging request".
Uses of uninitialized values detected by KMSAN may be exploitable b/c attacker frequently can affect uninit
values with spraying techniques. However, for these exploitability depends on how exactly the uninit value
is used in the code, and what it affects.
Think of what happens after the bug is triggered. Some bugs cause kernel panic and halt execution,
they are harder to exploit. For example, BUG reports halts the kernel. However, WARNING reports don't halt
execution in production builds. Debug bug detection tools (like KASAN, KMSAN, KCSAN, UBSAN) are also not enabled
in production builds, so attacker can freely exploit these bugs w/o being detected by these tools.
If you see an integer overflow, think how the overflowed value used later (if it's used as allocation size,
or an array index). If you see an out-of-bounds read, think if it's followed by an out-of-bounds write as well.
Some KCSAN data-races may be exploitable by skilled attackers as well. Think what data structures got corrupted
as the result of data races and how. However, note that kernel has lots of "benign" data races that don't lead
to any runtime misbehavior at all.
* Denial Of Service:
Determine if the bug can result in denial-of-service. Most bugs can, since they cause system crash,
hangs, deadlocks, or resource leaks. This is mostly applicable to WARNING bugs that won't cause system crash
in production. For these think what will be consequences of the violation of the kernel assumptions flagged
by the WARNING. In some cases the unexpected condition is also properly handled by the normal control flow
(e.g. with "if (WARN_ON(...))"), these won't cause denial-of-service. If the condition is not handled,
then it may or may not cause denial-of-service.
* Accessible From Unprivileged Processes:
Determine if the bug can be reached from a typical (non-root) user process that does NOT have any special capabilities
(like CAP_SYS_ADMIN, CAP_NET_ADMIN, CAP_NET_RAW, CAP_PERFMON) or access to device nodes restricted to root.
Assume that unprivileged_bpf_disabled=1, that is eBPF loading is not accessible. However, cBPF (classical BPF)
is still accessible to non-root processes.
Assume that user namespaces are not accessible, that is, the process cannot get the mentioned capabilities even
within a new user namespace (checked by ns_capable() function in the kernel sources).
* Accessible From User Namespaces:
Determine if the bug can be reached within a user-namespace where the process has all capabilities
(including CAP_SYS_ADMIN, CAP_NET_ADMIN, CAP_NET_RAW, CAP_PERFMON). Such capabilities are checked with ns_capable()
function in the kernel sources.
* VM Guest Trigger:
Determine if the bug can be triggered from the context of a typical KVM guest (e.g., set up by a QEMU VMM).
Consider accesses to standard Linux host paravirtualized features (virtio-blk, virtio-net, etc.),
and handling of VM exits in the KVM code.
* VM Host Trigger in The Confidential Computing Context:
Determine if the bug can be triggered in a confidential computing guest kernel from the context of a KVM host.
Consider access to standard Linux guest paravirtualized features (virtio-blk, virtio-net, etc.).
* Ethernet Network Trigger:
Determine if the bug can be triggered by processing ingress network Ethernet traffic, either directly (network stack)
or via drivers exposed to network data.
* Other Remote Trigger:
Determine if the bug can be triggered by processing remote traffic other than Ethernet (Wifi, Bluetooth, NFC, etc).
* Peripheral Trigger:
Determine if the bug can be triggered via an untrusted peripheral device that can be physically plugged
into a system, such as a USB device or a niche hardware driver handling external hardware inputs.
This is particularly important for mobile and desktop environments where users can plug in unknown devices.
* Malicious Filesystem Trigger:
Determine if the bug can be triggered by the kernel mounting and parsing a malicious filesystem image.
This is highly critical for Desktop and Mobile environments where external media or downloaded images
might be auto-mounted.
Don't make assumptions about the kernel source code (it may be different from what you assume it is).
Extensively use the provided code access tools (codesearch-*, git-*, grepper, etc)
to examine the actual source code, and confirm any assumptions.
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt:
The kernel bug report is:
BUG: TASK stack guard page was hit at ffffc90005947fe8 (stack is ffffc90005948000..ffffc90005950000)
Oops: stack guard page: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 13435 Comm: syz.0.11488 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:format_decode+0x17/0xe10 lib/vsprintf.c:2666
Code: 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 41 55 41 54 53 48 83 ec 28 49 89 d5 49 89 f6 48 89 fd <e8> 04 af 20 f6 41 0f b6 de 48 89 df 48 c7 c6 50 d2 17 90 e8 71 b4
RSP: 0018:ffffc90005947ff0 EFLAGS: 00010086
RAX: 1ffff92000b29042 RBX: dffffc0000000000 RCX: 1ffff92000b29040
RDX: ffffc90005948098 RSI: 0000000000000000 RDI: ffffffff8cdd9820
RBP: ffffffff8cdd9820 R08: ffffc90005948217 R09: 0000000000000000
R10: ffffc90005948200 R11: fffff52000b29043 R12: ffffc90005948200
R13: ffffc90005948098 R14: 0000000000000000 R15: ffffffff8cdd9820
FS: 0000000000000000(0000) GS:ffff888125289000(0063) knlGS:00000000f4fe1b40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffffc90005947fe8 CR3: 000000008f3f2000 CR4: 00000000003526f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000002
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
vsnprintf+0x102/0xee0 lib/vsprintf.c:2890
vprintk_store+0x371/0xd50 kernel/printk/printk.c:2307
vprintk_emit+0x192/0x560 kernel/printk/printk.c:2455
_printk+0xdd/0x130 kernel/printk/printk.c:2504
__dev_queue_xmit+0x1919/0x3950 net/core/dev.c:4891
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ipvlan_process_v4_outbound+0x44b/0x730 drivers/net/ipvlan/ipvlan_core.c:461
ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:565 [inline]
ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:627 [inline]
ipvlan_queue_xmit+0xac7/0x16c0 drivers/net/ipvlan/ipvlan_core.c:693
ipvlan_start_xmit+0x4a/0x160 drivers/net/ipvlan/ipvlan_main.c:226
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_hh_output include/net/neighbour.h:540 [inline]
neigh_output include/net/neighbour.h:554 [inline]
ip_finish_output2+0xc68/0x1070 net/ipv4/ip_output.c:237
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x29f/0x450 net/ipv4/ip_output.c:438
dst_output include/net/dst.h:470 [inline]
NF_HOOK+0x605/0x660 include/linux/netfilter.h:318
ip_vs_send_or_cont net/netfilter/ipvs/ip_vs_xmit.c:710 [inline]
ip_vs_dr_xmit+0x74a/0x9f0 net/netfilter/ipvs/ip_vs_xmit.c:1460
ip_vs_in_hook+0xd88/0x1bf0 net/netfilter/ipvs/ip_vs_core.c:2238
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619
nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ip_send_skb+0x45/0xc0 net/ipv4/ip_output.c:1510
udp_send_skb+0x7e4/0xf70 net/ipv4/udp.c:1161
udp_sendmsg+0x1937/0x21a0 net/ipv4/udp.c:1443
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x80a/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmmsg+0x2e7/0x4e0 net/socket.c:2834
__compat_sys_sendmmsg net/compat.c:360 [inline]
__do_compat_sys_sendmmsg net/compat.c:367 [inline]
__se_compat_sys_sendmmsg net/compat.c:364 [inline]
__ia32_compat_sys_sendmmsg+0xa2/0xc0 net/compat.c:364
do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
__do_fast_syscall_32+0x229/0x6e0 arch/x86/entry/syscall_32.c:307
do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7f8301c
Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
RSP: 002b:00000000f4fe150c EFLAGS: 00000206 ORIG_RAX: 0000000000000159
RAX: ffffffffffffffda RBX: 000000000000000a RCX: 00000000800005c0
RDX: 0000000000000001 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:format_decode+0x17/0xe10 lib/vsprintf.c:2666
Code: 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 41 55 41 54 53 48 83 ec 28 49 89 d5 49 89 f6 48 89 fd <e8> 04 af 20 f6 41 0f b6 de 48 89 df 48 c7 c6 50 d2 17 90 e8 71 b4
RSP: 0018:ffffc90005947ff0 EFLAGS: 00010086
RAX: 1ffff92000b29042 RBX: dffffc0000000000 RCX: 1ffff92000b29040
RDX: ffffc90005948098 RSI: 0000000000000000 RDI: ffffffff8cdd9820
RBP: ffffffff8cdd9820 R08: ffffc90005948217 R09: 0000000000000000
R10: ffffc90005948200 R11: fffff52000b29043 R12: ffffc90005948200
R13: ffffc90005948098 R14: 0000000000000000 R15: ffffffff8cdd9820
FS: 0000000000000000(0000) GS:ffff888125289000(0063) knlGS:00000000f4fe1b40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffffc90005947fe8 CR3: 000000008f3f2000 CR4: 00000000003526f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000002
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 00 90 90 90 90 90 add %dl,-0x6f6f6f70(%rax)
8: 90 nop
9: 90 nop
a: 90 nop
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 55 push %rbp
14: 41 57 push %r15
16: 41 56 push %r14
18: 41 55 push %r13
1a: 41 54 push %r12
1c: 53 push %rbx
1d: 48 83 ec 28 sub $0x28,%rsp
21: 49 89 d5 mov %rdx,%r13
24: 49 89 f6 mov %rsi,%r14
27: 48 89 fd mov %rdi,%rbp
* 2a: e8 04 af 20 f6 call 0xf620af33 <-- trapping instruction
2f: 41 0f b6 de movzbl %r14b,%ebx
33: 48 89 df mov %rbx,%rdi
36: 48 c7 c6 50 d2 17 90 mov $0xffffffff9017d250,%rsi
3d: e8 .byte 0xe8
3e: 71 b4 jno 0xfffffff4
Reply: The bug is a stack overflow caused by an infinite recursion loop in the network stack involving `ipvlan` and `ipvs` (IP Virtual Server).
### Root Cause Analysis
When a packet is transmitted through an `ipvlan` device configured in L3 mode, the driver calls `ipvlan_xmit_mode_l3()`, which in turn calls `ipvlan_skb_crossing_ns()`. This function scrubs the socket buffer (`skb`) by calling `skb_scrub_packet()`, which clears various state flags, including the `skb->ipvs_property` flag via `ipvs_reset(skb)`.
After scrubbing, the packet is routed and passed to `ip_local_out()`, which triggers the `NF_INET_LOCAL_OUT` netfilter hooks. IPVS registers its `ip_vs_in_hook()` at this exact hook. Normally, IPVS avoids processing the same packet multiple times by checking if `skb->ipvs_property` is set. However, because `ipvlan` just cleared this flag, IPVS fails to recognize that the packet was already processed and processes it again.
If the packet matches an IPVS service configured in Direct Routing (DR) mode, IPVS will route the packet to its destination (`ip_vs_dr_xmit()`). If the routing table directs the packet back to the same `ipvlan` device, the packet is queued to the `ipvlan` device again via `dev_queue_xmit()`.
This creates an infinite recursion loop:
`ipvlan_start_xmit` -> `ipvlan_xmit_mode_l3` -> `ip_local_out` -> `ip_vs_in_hook` -> `ip_vs_dr_xmit` -> `dev_queue_xmit` -> `ipvlan_start_xmit` ...
The recursion continues until the kernel stack overflows and hits the stack guard page, resulting in a kernel panic.
### Security Impact
* **Exploitable:** **False**. The stack overflow deterministically hits the 4KB stack guard page (as seen in the `Oops: stack guard page` report). The guard page triggers a page fault and halts the kernel before any adjacent memory can be corrupted, preventing privilege escalation or arbitrary code execution.
* **Denial Of Service:** **True**. The bug reliably causes a kernel panic, leading to a complete system crash.
* **Accessible From Unprivileged Processes:** **False**. Setting up the required `ipvlan` device and IPVS rules requires `CAP_NET_ADMIN` privileges in the network namespace.
* **Accessible From User Namespaces:** **True**. Both `ipvlan` devices (e.g., on top of a `dummy` device) and IPVS can be fully configured inside an unprivileged user namespace. A local attacker can create a new user/network namespace, acquire `CAP_NET_ADMIN`, set up the looping configuration, and send a single packet to crash the host system.
* **Network / Remote Triggers:** **False**. Triggering the bug remotely would require the target system to already have this specific, self-looping misconfiguration set up by an administrator. Since this configuration inherently breaks networking for the involved IPs and serves no legitimate purpose, it is not a realistic remote attack vector.
|
| 6/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 16120
output: 25
thoughts: 1463
Thoughts: **Analyzing a Stack Overflow in IPvlan and IPVS**
Okay, so I've got a stack overflow report on my hands. The kernel's stack guard page was hit, indicating a stack overflow, and the address gives me a starting point. This is a crash, plain and simple, and I need to figure out why.
The call trace tells the story: it's a deep recursion, starting and ending with `ipvlan_start_xmit`. Right away, I see a loop. Diving in, the recursion looks like this: `ipvlan_start_xmit` calls `ipvlan_queue_xmit`, which goes down a rabbit hole involving `ipvlan_process_outbound`, `ipvlan_process_v4_outbound`, `ip_local_out`, and then gets routed, using `netfilter` (hooks) to an `ipvs` function, specifically `ip_vs_dr_xmit` before it finally circles back. Ultimately, the packet is sent back into the `ipvlan` device from `dev_queue_xmit` after it has gone through `ipvs` Direct Routing.
The key is that `ipvlan_start_xmit` is initiating the packet transmission. It's calling `ipvlan_process_v4_outbound`, which in turn calls `ip_local_out`. My immediate thought is, netfilter hooks will come into play, and sure enough, `ip_vs_in_hook` is involved. Direct Routing from `ipvs` (`ip_vs_dr_xmit`) is sending the packet, which is causing the problem. If the route points back to the `ipvlan` device, we've got a self-referential loop, and that's the smoking gun.
Now, is this exploitable? A stack overflow is a denial of service. The question is, can it be triggered by someone who *isn't* root? Configuring `ipvlan` and `ipvs` both require `CAP_NET_ADMIN`, and this can be done in a user namespace. This means a regular user, within a user namespace, *could* potentially trigger this. I need to confirm if `ipvs` is allowed in user namespaces. I need to go dig into the initialization code, likely around `ip_vs_init` or similar, to be certain.
|
| 7/2 |
2026/06/02 00:31 |
tool |
grepper |
0m
Args: map[Expression:register_pernet_subsys.*ip_vs]
Results: map[Output:net/netfilter/ipvs/ip_vs_core.c=2565=static int __init ip_vs_init(void)
--
net/netfilter/ipvs/ip_vs_core.c-2582-
net/netfilter/ipvs/ip_vs_core.c:2583: ret = register_pernet_subsys(&ipvs_core_ops); /* Alloc ip_vs struct */
net/netfilter/ipvs/ip_vs_core.c-2584- if (ret < 0)
--
net/netfilter/ipvs/ip_vs_core.c=2614=static void __exit ip_vs_cleanup(void)
--
net/netfilter/ipvs/ip_vs_core.c-2617- unregister_pernet_device(&ipvs_core_dev_ops);
net/netfilter/ipvs/ip_vs_core.c:2618: unregister_pernet_subsys(&ipvs_core_ops); /* free ip_vs struct */
net/netfilter/ipvs/ip_vs_core.c-2619- ip_vs_conn_cleanup();
--
net/netfilter/ipvs/ip_vs_ftp.c=619=static int __init ip_vs_ftp_init(void)
--
net/netfilter/ipvs/ip_vs_ftp.c-621- /* rcu_barrier() is called by netns on error */
net/netfilter/ipvs/ip_vs_ftp.c:622: return register_pernet_subsys(&ip_vs_ftp_ops);
net/netfilter/ipvs/ip_vs_ftp.c-623-}
--
net/netfilter/ipvs/ip_vs_ftp.c=628=static void __exit ip_vs_ftp_exit(void)
--
net/netfilter/ipvs/ip_vs_ftp.c-630- exiting_module = true;
net/netfilter/ipvs/ip_vs_ftp.c:631: unregister_pernet_subsys(&ip_vs_ftp_ops);
net/netfilter/ipvs/ip_vs_ftp.c-632- /* rcu_barrier() is called by netns */
--
net/netfilter/ipvs/ip_vs_lblc.c=607=static int __init ip_vs_lblc_init(void)
--
net/netfilter/ipvs/ip_vs_lblc.c-610-
net/netfilter/ipvs/ip_vs_lblc.c:611: ret = register_pernet_subsys(&ip_vs_lblc_ops);
net/netfilter/ipvs/ip_vs_lblc.c-612- if (ret)
--
net/netfilter/ipvs/ip_vs_lblc.c-616- if (ret)
net/netfilter/ipvs/ip_vs_lblc.c:617: unregister_pernet_subsys(&ip_vs_lblc_ops);
net/netfilter/ipvs/ip_vs_lblc.c-618- return ret;
--
net/netfilter/ipvs/ip_vs_lblc.c=621=static void __exit ip_vs_lblc_cleanup(void)
--
net/netfilter/ipvs/ip_vs_lblc.c-623- unregister_ip_vs_scheduler(&ip_vs_lblc_scheduler);
net/netfilter/ipvs/ip_vs_lblc.c:624: unregister_pernet_subsys(&ip_vs_lblc_ops);
net/netfilter/ipvs/ip_vs_lblc.c-625- rcu_barrier();
--
net/netfilter/ipvs/ip_vs_lblcr.c=792=static int __init ip_vs_lblcr_init(void)
--
net/netfilter/ipvs/ip_vs_lblcr.c-795-
net/netfilter/ipvs/ip_vs_lblcr.c:796: ret = register_pernet_subsys(&ip_vs_lblcr_ops);
net/netfilter/ipvs/ip_vs_lblcr.c-797- if (ret)
--
net/netfilter/ipvs/ip_vs_lblcr.c-801- if (ret)
net/netfilter/ipvs/ip_vs_lblcr.c:802: unregister_pernet_subsys(&ip_vs_lblcr_ops);
net/netfilter/ipvs/ip_vs_lblcr.c-803- return ret;
--
net/netfilter/ipvs/ip_vs_lblcr.c=806=static void __exit ip_vs_lblcr_cleanup(void)
--
net/netfilter/ipvs/ip_vs_lblcr.c-808- unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
net/netfilter/ipvs/ip_vs_lblcr.c:809: unregister_pernet_subsys(&ip_vs_lblcr_ops);
net/netfilter/ipvs/ip_vs_lblcr.c-810- rcu_barrier();
]
|
| 8/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 19442
output: 22
thoughts: 50
Thoughts: Okay, here's my take on those thoughts, framed as my own:
**Investigating IPVS and User Namespaces**
Alright, so IPVS is a registered pernet subsystem. My initial thought is, can we actually configure this thing from a user namespace? That's a key question for this line of investigation. Given what I know about IPVS's mechanisms, I know it utilizes either netlink or setsockopt. Right, that's what I need to verify. Now I need to drill down and check `ip_vs_genl_family`. That's where I need to start. From there I'll be able to tell if user namespaces can interact with it.
|
| 9/2 |
2026/06/02 00:31 |
tool |
grepper |
0m
Args: map[Expression:ip_vs_genl_family]
Results: map[Output:net/netfilter/ipvs/ip_vs_ctl.c=3799=static struct nf_sockopt_ops ip_vs_sockopts = {
--
net/netfilter/ipvs/ip_vs_ctl.c-3814-/* IPVS genetlink family */
net/netfilter/ipvs/ip_vs_ctl.c:3815:static struct genl_family ip_vs_genl_family;
net/netfilter/ipvs/ip_vs_ctl.c-3816-
--
net/netfilter/ipvs/ip_vs_ctl.c=3997=static int ip_vs_genl_dump_service(struct sk_buff *skb,
--
net/netfilter/ipvs/ip_vs_ctl.c-4003- hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
net/netfilter/ipvs/ip_vs_ctl.c:4004: &ip_vs_genl_family, NLM_F_MULTI,
net/netfilter/ipvs/ip_vs_ctl.c-4005- IPVS_CMD_NEW_SERVICE);
--
net/netfilter/ipvs/ip_vs_ctl.c=4201=static int ip_vs_genl_dump_dest(struct sk_buff *skb, struct ip_vs_dest *dest,
--
net/netfilter/ipvs/ip_vs_ctl.c-4206- hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
net/netfilter/ipvs/ip_vs_ctl.c:4207: &ip_vs_genl_family, NLM_F_MULTI,
net/netfilter/ipvs/ip_vs_ctl.c-4208- IPVS_CMD_NEW_DEST);
--
net/netfilter/ipvs/ip_vs_ctl.c=4362=static int ip_vs_genl_dump_daemon(struct sk_buff *skb, __u32 state,
--
net/netfilter/ipvs/ip_vs_ctl.c-4367- hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
net/netfilter/ipvs/ip_vs_ctl.c:4368: &ip_vs_genl_family, NLM_F_MULTI,
net/netfilter/ipvs/ip_vs_ctl.c-4369- IPVS_CMD_NEW_DAEMON);
--
net/netfilter/ipvs/ip_vs_ctl.c=4662=static int ip_vs_genl_get_cmd(struct sk_buff *skb, struct genl_info *info)
--
net/netfilter/ipvs/ip_vs_ctl.c-4688-
net/netfilter/ipvs/ip_vs_ctl.c:4689: reply = genlmsg_put_reply(msg, info, &ip_vs_genl_family, 0, reply_cmd);
net/netfilter/ipvs/ip_vs_ctl.c-4690- if (reply == NULL)
--
net/netfilter/ipvs/ip_vs_ctl.c=4761=static const struct genl_small_ops ip_vs_genl_ops[] = {
--
net/netfilter/ipvs/ip_vs_ctl.c-4860-
net/netfilter/ipvs/ip_vs_ctl.c:4861:static struct genl_family ip_vs_genl_family __ro_after_init = {
net/netfilter/ipvs/ip_vs_ctl.c-4862- .hdrsize = 0,
--
net/netfilter/ipvs/ip_vs_ctl.c=4875=static int __init ip_vs_genl_register(void)
net/netfilter/ipvs/ip_vs_ctl.c-4876-{
net/netfilter/ipvs/ip_vs_ctl.c:4877: return genl_register_family(&ip_vs_genl_family);
net/netfilter/ipvs/ip_vs_ctl.c-4878-}
--
net/netfilter/ipvs/ip_vs_ctl.c=4880=static void ip_vs_genl_unregister(void)
net/netfilter/ipvs/ip_vs_ctl.c-4881-{
net/netfilter/ipvs/ip_vs_ctl.c:4882: genl_unregister_family(&ip_vs_genl_family);
net/netfilter/ipvs/ip_vs_ctl.c-4883-}
]
|
| 10/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 20897
output: 47
thoughts: 16
Thoughts: Here's my take on those thoughts:
**Peering into the Kernel's IPVS Family Definition**
Okay, so I need to get a handle on the `ip_vs_genl_family`. My instinct is to dive straight into the definition. It's the first place to start – understanding the foundation of this particular aspect of the kernel's IP Virtual Server implementation is key to anything I want to understand more broadly. I'm going to pull up that definition and quickly digest its structure, the data it contains, and how it relates to the broader GENL (Generic Netlink) framework. I'm especially interested in the fields and their meaning as that will inform my future study.
|
| 11/2 |
2026/06/02 00:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/ipvs/ip_vs_ctl.c Name:ip_vs_genl_family]
Results: map[SourceCode:4861: static struct genl_family ip_vs_genl_family __ro_after_init = {
4862: .hdrsize = 0,
4863: .name = IPVS_GENL_NAME,
4864: .version = IPVS_GENL_VERSION,
4865: .maxattr = IPVS_CMD_ATTR_MAX,
4866: .policy = ip_vs_cmd_policy,
4867: .netnsok = true, /* Make ipvsadm to work on netns */
4868: .module = THIS_MODULE,
4869: .small_ops = ip_vs_genl_ops,
4870: .n_small_ops = ARRAY_SIZE(ip_vs_genl_ops),
4871: .resv_start_op = IPVS_CMD_FLUSH + 1,
4872: .parallel_ops = 1,
4873: };
SourceFile:net/netfilter/ipvs/ip_vs_ctl.c]
|
| 12/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 21409
output: 23
thoughts: 25
Thoughts: Okay, here's my interpretation of those thoughts, tailored for an expert audience, presented in the first person:
**Investigating User Namespaces and Network Configurations**
Alright, so `.netnsok = true`. That's a key indicator, right? It immediately signals that whatever configuration this refers to is compatible with user namespaces. That opens up a whole range of possibilities for isolation and experimentation. But, I need to understand the implications here in relation to, say, `ipvlan`. I'm going to have to do a deeper dive to understand what this will look like. Are there any caveats there? Does this mean I can instantiate and configure it directly within the user namespace? Or are there still some kernel-level dependencies or restrictions that I need to be aware of? I need to think through how this will interact with the larger network stack and figure out how to best integrate it into a sandboxed environment. What are the security implications of all this?
|
| 13/2 |
2026/06/02 00:31 |
tool |
grepper |
0m
Args: map[Expression:rtnl_link_ops.*ipvlan]
Results: map[Output:drivers/net/ipvlan/ipvlan_main.c=696=static struct net *ipvlan_get_link_net(const struct net_device *dev)
--
drivers/net/ipvlan/ipvlan_main.c-702-
drivers/net/ipvlan/ipvlan_main.c:703:static struct rtnl_link_ops ipvlan_link_ops = {
drivers/net/ipvlan/ipvlan_main.c-704- .kind = "ipvlan",
--
drivers/net/ipvlan/ipvlan_main.c=725=static int ipvlan_device_event(struct notifier_block *unused,
--
drivers/net/ipvlan/ipvlan_main.c-767- list_for_each_entry_safe(ipvlan, next, &port->ipvlans, pnode)
drivers/net/ipvlan/ipvlan_main.c:768: ipvlan->dev->rtnl_link_ops->dellink(ipvlan->dev,
drivers/net/ipvlan/ipvlan_main.c-769- &lst_kill);
]
|
| 14/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 21941
output: 43
thoughts: 12
Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience:
**Diving into `ipvlan_link_ops`**
Alright, time to dig into `ipvlan_link_ops`. I need to refresh my understanding of the current implementation and see if there are any subtle points I've overlooked. Let's start with a quick code review. I'll focus on the data structures and control flow first, specifically looking at how packets are handled, the address configuration, and the interaction with the underlying physical interface. I'm particularly interested in the synchronization primitives used and potential race conditions. I want to identify any areas where performance can be improved. Are there any inefficient loops, unnecessary copies, or suboptimal locking strategies? This is really about understanding the core of the IPvlan interface and ensuring its correctness and efficiency under various load conditions. Need to check for any memory leaks or resource exhaustion as well.
|
| 15/2 |
2026/06/02 00:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/net/ipvlan/ipvlan_main.c Name:ipvlan_link_ops]
Results: map[SourceCode: 703: static struct rtnl_link_ops ipvlan_link_ops = {
704: .kind = "ipvlan",
705: .priv_size = sizeof(struct ipvl_dev),
706:
707: .setup = ipvlan_link_setup,
708: .newlink = ipvlan_link_new,
709: .dellink = ipvlan_link_delete,
710: .get_link_net = ipvlan_get_link_net,
711: };
SourceFile:drivers/net/ipvlan/ipvlan_main.c]
|
| 16/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 22377
output: 47
thoughts: 456
Thoughts: **My Analysis of `ipvlan` in User Namespaces**
Okay, so I'm thinking about whether we can allow `ipvlan` within a user namespace. My initial instinct is to check the `rtnl_link_ops` structure. While it often includes `.netns_refund = true` or similar flags, the crucial thing is if the interface can be *created* in the first place.
Let me see... can we create an `ipvlan` interface within a user namespace directly? Actually, `rtnl_link_ops` registration alone doesn't prevent this. It's `rtnl_create_link` that contains the restriction, checking if the user has `CAP_NET_ADMIN` privileges in the network namespace.
Ah, that's the key. An unprivileged user can create their own user namespace, and then, within that, a new network namespace. They inherit `CAP_NET_ADMIN` within that nested network namespace and should be able to create `ipvlan` links, assuming the module is loaded or autoloading can be triggered.
Hold on a second. `ipvlan` needs a physical device to attach to, right? Can we bind an `ipvlan` to a `veth` or `dummy` device? Yep, those can be created within a user namespace as well. That means an unprivileged user can effectively:
1. Create a user and network namespace.
2. Create a `dummy` device.
3. Create an `ipvlan` interface on top of the `dummy` device.
4. Configure `ipvs` within the same network namespace.
5. Send a packet that would loop between the `ipvlan` and `ipvs`.
I want to verify this loop mechanism. Let's look at the stack trace. I'm seeing: `ipvlan_start_xmit` -> `ipvlan_queue_xmit` -> `ipvlan_process_outbound` -> `ipvlan_process_v4_outbound` -> `ip_local_out` -> `nf_hook_slow` -> `ip_vs_in_hook` -> `ip_vs_dr_xmit` -> `ip_output` -> `dev_queue_xmit` -> `ipvlan_start_xmit`.
Alright, I should take a closer look at `ipvlan_process_v4_outbound` now.
|
| 17/2 |
2026/06/02 00:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/net/ipvlan/ipvlan_core.c Name:ipvlan_process_v4_outbound]
Results: map[SourceCode: 428: static noinline_for_stack int ipvlan_process_v4_outbound(struct sk_buff *skb)
429: {
430: struct net_device *dev = skb->dev;
431: struct net *net = dev_net(dev);
432: int err, ret = NET_XMIT_DROP;
433: const struct iphdr *ip4h;
434: struct rtable *rt;
435: struct flowi4 fl4 = {
436: .flowi4_oif = dev->ifindex,
437: .flowi4_flags = FLOWI_FLAG_ANYSRC,
438: .flowi4_mark = skb->mark,
439: };
440:
441: if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
442: goto err;
443:
444: ip4h = ip_hdr(skb);
445: fl4.daddr = ip4h->daddr;
446: fl4.saddr = ip4h->saddr;
447: fl4.flowi4_dscp = ip4h_dscp(ip4h);
448:
449: rt = ip_route_output_flow(net, &fl4, NULL);
450: if (IS_ERR(rt))
451: goto err;
452:
453: if (rt->rt_type != RTN_UNICAST && rt->rt_type != RTN_LOCAL) {
454: ip_rt_put(rt);
455: goto err;
456: }
457: skb_dst_set(skb, &rt->dst);
458:
459: memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
460:
461: err = ip_local_out(net, NULL, skb);
462: if (unlikely(net_xmit_eval(err)))
463: DEV_STATS_INC(dev, tx_errors);
464: else
465: ret = NET_XMIT_SUCCESS;
466: goto out;
467: err:
468: DEV_STATS_INC(dev, tx_errors);
469: kfree_skb(skb);
470: out:
471: return ret;
472: }
SourceFile:drivers/net/ipvlan/ipvlan_core.c]
|
| 18/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 24139
output: 21
thoughts: 67
Thoughts: **My Internal IP Packet Flow Analysis**
Okay, so I'm tracing this outbound IPv4 traffic. My initial focus is on `ipvlan_process_v4_outbound`. That function is setting up the necessary routing for the packet, which is the logical first step. Then, it calls `ip_local_out`. My mental model of this is pretty clear, but I'll step through it again, slowly.
`ip_local_out` is the key function to inspect here. I know it's where the packet is passed through the `NF_INET_LOCAL_OUT` Netfilter hook. This is where I can apply my expertise. I need to understand what rules might be active at this point. In this specific scenario, are there any Netfilter rules that I might be interested in?
Since I'm looking at routing and packet traversal, I should take a look at the interaction of other features as well. I know IPVS (IP Virtual Server) registers netfilter hooks, and I should make sure that I understand how they might affect this particular packet flow. Given this context, let me investigate the IPVS hooks and see what their configurations are. This will help determine how that outbound traffic might be impacted, if at all.
|
| 19/2 |
2026/06/02 00:31 |
tool |
grepper |
0m
Args: map[Expression:ip_vs_in_hook]
Results: map[Output:net/netfilter/ipvs/ip_vs_core.c=2085=static unsigned int
net/netfilter/ipvs/ip_vs_core.c:2086:ip_vs_in_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state)
net/netfilter/ipvs/ip_vs_core.c-2087-{
--
net/netfilter/ipvs/ip_vs_core.c=2308=static const struct nf_hook_ops ip_vs_ops4[] = {
--
net/netfilter/ipvs/ip_vs_core.c-2319- {
net/netfilter/ipvs/ip_vs_core.c:2320: .hook = ip_vs_in_hook,
net/netfilter/ipvs/ip_vs_core.c-2321- .pf = NFPROTO_IPV4,
--
net/netfilter/ipvs/ip_vs_core.c-2333- {
net/netfilter/ipvs/ip_vs_core.c:2334: .hook = ip_vs_in_hook,
net/netfilter/ipvs/ip_vs_core.c-2335- .pf = NFPROTO_IPV4,
--
net/netfilter/ipvs/ip_vs_core.c=2357=static const struct nf_hook_ops ip_vs_ops6[] = {
--
net/netfilter/ipvs/ip_vs_core.c-2368- {
net/netfilter/ipvs/ip_vs_core.c:2369: .hook = ip_vs_in_hook,
net/netfilter/ipvs/ip_vs_core.c-2370- .pf = NFPROTO_IPV6,
--
net/netfilter/ipvs/ip_vs_core.c-2382- {
net/netfilter/ipvs/ip_vs_core.c:2383: .hook = ip_vs_in_hook,
net/netfilter/ipvs/ip_vs_core.c-2384- .pf = NFPROTO_IPV6,
]
|
| 20/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 25058
output: 45
thoughts: 16
Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience:
**Investigating `ip_vs_ops4` Registration**
Okay, so I need to figure out where `ip_vs_ops4` is actually getting registered within the system. I'm assuming it's part of the IP Virtual Server (IPVS) infrastructure, so that's where I'll start digging. My primary concern is pinpointing the registration points – are we talking static registration during module load, dynamic registration through some netlink interface, or something else entirely? I need to understand the lifecycle of this thing. Knowing this, I can then track how it is utilized, and trace the calls to understand its behavior within the kernel. I will probably begin by grepping the kernel source code to find its definition and usages. Then I'll trace its registration functions to get an idea of the surrounding logic. This should quickly narrow down the possibilities and give me a clear picture of how this structure integrates within the larger IPVS framework. I’ll be looking for `module_init` calls, `netlink` registration functions, or any other initialization routines that might be relevant. Once I've found the registration points, I can investigate potential race conditions, timing issues, or dependency problems associated with this function.
|
| 21/2 |
2026/06/02 00:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/ipvs/ip_vs_core.c Name:ip_vs_ops4]
Results: map[SourceCode:2308: static const struct nf_hook_ops ip_vs_ops4[] = {
2309: /* After packet filtering, change source only for VS/NAT */
2310: {
2311: .hook = ip_vs_out_hook,
2312: .pf = NFPROTO_IPV4,
2313: .hooknum = NF_INET_LOCAL_IN,
2314: .priority = NF_IP_PRI_NAT_SRC - 2,
2315: },
2316: /* After packet filtering, forward packet through VS/DR, VS/TUN,
2317: * or VS/NAT(change destination), so that filtering rules can be
2318: * applied to IPVS. */
2319: {
2320: .hook = ip_vs_in_hook,
2321: .pf = NFPROTO_IPV4,
2322: .hooknum = NF_INET_LOCAL_IN,
2323: .priority = NF_IP_PRI_NAT_SRC - 1,
2324: },
2325: /* Before ip_vs_in, change source only for VS/NAT */
2326: {
2327: .hook = ip_vs_out_hook,
2328: .pf = NFPROTO_IPV4,
2329: .hooknum = NF_INET_LOCAL_OUT,
2330: .priority = NF_IP_PRI_NAT_DST + 1,
2331: },
2332: /* After mangle, schedule and forward local requests */
2333: {
2334: .hook = ip_vs_in_hook,
2335: .pf = NFPROTO_IPV4,
2336: .hooknum = NF_INET_LOCAL_OUT,
2337: .priority = NF_IP_PRI_NAT_DST + 2,
2338: },
2339: /* After packet filtering (but before ip_vs_out_icmp), catch icmp
2340: * destined for 0.0.0.0/0, which is for incoming IPVS connections */
2341: {
2342: .hook = ip_vs_forward_icmp,
2343: .pf = NFPROTO_IPV4,
2344: .hooknum = NF_INET_FORWARD,
2345: .priority = 99,
2346: },
2347: /* After packet filtering, change source only for VS/NAT */
2348: {
2349: .hook = ip_vs_out_hook,
2350: .pf = NFPROTO_IPV4,
2351: .hooknum = NF_INET_FORWARD,
2352: .priority = 100,
2353: },
2354: };
SourceFile:net/netfilter/ipvs/ip_vs_core.c]
|
| 22/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 26208
output: 48
thoughts: 100
Thoughts: **My Analysis of the Outbound IPv4 Packet Flow and IPVS Integration**
Okay, so I'm tracing this outbound IPv4 packet flow and how IPVS gets involved. I see that the `ip_vs_in_hook` is registered at `NF_INET_LOCAL_OUT`. That immediately tells me it's going to be triggered when a packet is about to leave the local network interface, presumably after routing decisions have been made.
When `ipvlan_process_v4_outbound` calls `ip_local_out`, this is the crucial point. This is where the packet is about to go out, and crucially, this call triggers `ip_vs_in_hook`. This means IPVS gets a chance to look at the packet right before it hits the wire.
Then, `ip_vs_in_hook` does its thing. It processes the packet, likely looking for any matching IPVS services or rules. If a match is found, implying the packet is destined for a virtual service, it's forwarded.
And the stack trace is telling me the forwarding is handled by `ip_vs_dr_xmit`. That makes perfect sense. Given my expertise, I instantly know that's the "Direct Routing" transmit function, which implies the packet is likely being sent directly to the real server, potentially bypassing the normal routing path, as is typical with the Direct Routing mode I'm familiar with.
|
| 23/2 |
2026/06/02 00:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/ipvs/ip_vs_xmit.c Name:ip_vs_dr_xmit]
Results: map[SourceCode:1436: /*
1437: * Direct Routing transmitter
1438: * Used for ANY protocol
1439: */
1440: int
1441: ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
1442: struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
1443: {
1444: int local;
1445:
1446: local = __ip_vs_get_out_rt(cp->ipvs, cp->af, skb, cp->dest, cp->daddr.ip,
1447: IP_VS_RT_MODE_LOCAL |
1448: IP_VS_RT_MODE_NON_LOCAL |
1449: IP_VS_RT_MODE_KNOWN_NH, NULL, ipvsh);
1450: if (local < 0)
1451: goto tx_error;
1452: if (local)
1453: return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1);
1454:
1455: ip_send_check(ip_hdr(skb));
1456:
1457: /* Another hack: avoid icmp_send in ip_fragment */
1458: skb->ignore_df = 1;
1459:
1460: ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0);
1461:
1462: return NF_STOLEN;
1463:
1464: tx_error:
1465: kfree_skb(skb);
1466: return NF_STOLEN;
1467: }
SourceFile:net/netfilter/ipvs/ip_vs_xmit.c]
|
| 24/2 |
2026/06/02 00:31 |
llm |
expert |
0m
Model:
Tokens:
input: 27194
output: 49
thoughts: 22
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:
**My Deep Dive into `ip_vs_dr_xmit`**
Alright, so I'm thinking about the flow in Direct Routing with IPVS, specifically the `ip_vs_dr_xmit` function. My brain immediately jumps to its connection point: it calls `ip_vs_send_or_cont`. That's the crux of the matter, isn't it? `ip_vs_dr_xmit` is *responsible* for the direct routing transmission, but it's clearly *offloading* the actual sending logic to `ip_vs_send_or_cont`. This probably indicates it's managing the encapsulation or manipulation of the packet at this stage to meet the direct routing requirements, but the actual network transmission is handled elsewhere.
I'd want to quickly check the arguments passed from `ip_vs_dr_xmit` to `ip_vs_send_or_cont`. Are we passing the packet buffer directly? Are we setting any flags or options related to the direct route? Is there any kind of hook setup for any other logic?
This also makes me wonder if `ip_vs_send_or_cont` handles both the "send" and "continuation" paths of a packet. It's a broad name, suggesting some level of flexibility. So, I would check if this function is used in other IPVS areas, for example NAT and other types of routes.
I assume that the core functions associated with routing are dealt with here.
If I wanted to dig deeper, I would think about race conditions, and how to verify correctness.
|
| 25/2 |
2026/06/02 00:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/ipvs/ip_vs_xmit.c Name:ip_vs_send_or_cont]
Results: map[SourceCode: 696: /* return NF_STOLEN (sent) or NF_ACCEPT if local=1 (not sent) */
697: static inline int ip_vs_send_or_cont(int pf, struct sk_buff *skb,
698: struct ip_vs_conn *cp, int local)
699: {
700: int ret = NF_STOLEN;
701:
702: skb->ipvs_property = 1;
703: if (likely(!(cp->flags & IP_VS_CONN_F_NFCT)))
704: ip_vs_notrack(skb);
705: if (!local) {
706: ip_vs_drop_early_demux_sk(skb);
707: skb_forward_csum(skb);
708: if (skb->dev)
709: skb_clear_tstamp(skb);
710: NF_HOOK(pf, NF_INET_LOCAL_OUT, cp->ipvs->net, NULL, skb,
711: NULL, skb_dst(skb)->dev, dst_output);
712: } else
713: ret = NF_ACCEPT;
714: return ret;
715: }
SourceFile:net/netfilter/ipvs/ip_vs_xmit.c]
|
| 26/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 28022
output: 46
thoughts: 369
Thoughts: **IPvlan, IPVS, and the Perilous Loop: A Deep Dive**
Okay, so I'm tracing this packet flow and immediately see a potential nightmare scenario with IPvlan and IPVS. We start in `ip_vs_send_or_cont`, and that's where the initial trigger happens – `NF_HOOK(pf, NF_INET_LOCAL_OUT, ..., dst_output)`. Standard stuff, so far. `dst_output` hands it off to `ip_output` (IPv4, naturally), which ends up in `ip_finish_output2`. That calls `neigh_output`, and finally `dev_queue_xmit`.
Here's where the red flags go up: if the destination device is an `ipvlan` interface, we're back where we started, calling `ipvlan_start_xmit` again. We're looking at the definition of `ipvlan`, it's a virtual device and the `ndo_start_xmit` is set to `ipvlan_start_xmit`. So it calls `ipvlan_queue_xmit`. Fine, `ipvlan_queue_xmit` has to figure out if it's local or outbound. In the outbound case, it's `ipvlan_process_outbound` -> `ipvlan_process_v4_outbound`, which ultimately leads to routing the packet again via `ip_local_out`. And *that* goes through `NF_INET_LOCAL_OUT` hooks *again*, and predictably `ip_vs_in_hook` catches the packet yet again.
This is a loop! An indefinite, stack-overflow-inducing loop, unless we're missing something obvious. We're back where we started with the same packet.
Okay, let's calm down and try to remember. Is there a guardrail anywhere? A check to prevent this recursive madness? Did someone account for this in the design?
I vaguely remember some `skb->ipvs_property` assignment. It's set in `ip_vs_send_or_cont` to 1. The key is now - does `ip_vs_in_hook` or any of the code it calls check `skb->ipvs_property`? That would be the obvious place to break the loop! I need to go look... this could be a nasty bug.
|
| 27/2 |
2026/06/02 00:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/ipvs/ip_vs_core.c Name:ip_vs_in_hook]
Results: map[SourceCode:2081: /*
2082: * Check if it's for virtual services, look it up,
2083: * and send it on its way...
2084: */
2085: static unsigned int
2086: ip_vs_in_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state)
2087: {
2088: struct netns_ipvs *ipvs = net_ipvs(state->net);
2089: unsigned int hooknum = state->hook;
2090: struct ip_vs_iphdr iph;
2091: struct ip_vs_protocol *pp;
2092: struct ip_vs_proto_data *pd;
2093: struct ip_vs_conn *cp;
2094: int ret, pkts;
2095: struct sock *sk;
2096: int af = state->pf;
2097:
2098: /* Already marked as IPVS request or reply? */
2099: if (skb->ipvs_property)
2100: return NF_ACCEPT;
2101:
2102: /*
2103: * Big tappo:
2104: * - remote client: only PACKET_HOST
2105: * - route: used for struct net when skb->dev is unset
2106: */
2107: if (unlikely((skb->pkt_type != PACKET_HOST &&
2108: hooknum != NF_INET_LOCAL_OUT) ||
2109: !skb_dst(skb))) {
2110: ip_vs_fill_iph_skb(af, skb, false, &iph);
2111: IP_VS_DBG_BUF(12, "packet type=%d proto=%d daddr=%s"
2112: " ignored in hook %u\n",
2113: skb->pkt_type, iph.protocol,
2114: IP_VS_DBG_ADDR(af, &iph.daddr), hooknum);
2115: return NF_ACCEPT;
2116: }
2117: /* ipvs enabled in this netns ? */
2118: if (unlikely(sysctl_backup_only(ipvs)))
2119: return NF_ACCEPT;
2120:
2121: ip_vs_fill_iph_skb(af, skb, false, &iph);
2122:
2123: /* Bad... Do not break raw sockets */
2124: sk = skb_to_full_sk(skb);
2125: if (unlikely(sk && hooknum == NF_INET_LOCAL_OUT &&
2126: af == AF_INET)) {
2127:
2128: if (sk->sk_family == PF_INET && inet_test_bit(NODEFRAG, sk))
2129: return NF_ACCEPT;
2130: }
2131:
2132: #ifdef CONFIG_IP_VS_IPV6
2133: if (af == AF_INET6) {
2134: if (unlikely(iph.protocol == IPPROTO_ICMPV6)) {
2135: int related;
2136: int verdict = ip_vs_in_icmp_v6(ipvs, skb, &related,
2137: hooknum, &iph);
2138:
2139: if (related)
2140: return verdict;
2141: }
2142: } else
2143: #endif
2144: if (unlikely(iph.protocol == IPPROTO_ICMP)) {
2145: int related;
2146: int verdict = ip_vs_in_icmp(ipvs, skb, &related,
2147: hooknum);
2148:
2149: if (related)
2150: return verdict;
2151: }
2152:
2153: /* Protocol supported? */
2154: pd = ip_vs_proto_data_get(ipvs, iph.protocol);
2155: if (unlikely(!pd)) {
2156: /* The only way we'll see this packet again is if it's
2157: * encapsulated, so mark it with ipvs_property=1 so we
2158: * skip it if we're ignoring tunneled packets
2159: */
2160: if (sysctl_ignore_tunneled(ipvs))
2161: skb->ipvs_property = 1;
2162:
2163: return NF_ACCEPT;
2164: }
2165: pp = pd->pp;
2166: /*
2167: * Check if the packet belongs to an existing connection entry
2168: */
2169: cp = INDIRECT_CALL_1(pp->conn_in_get, ip_vs_conn_in_get_proto,
2170: ipvs, af, skb, &iph);
2171:
2172: if (!iph.fragoffs && is_new_conn(skb, &iph) && cp) {
2173: int conn_reuse_mode = sysctl_conn_reuse_mode(ipvs);
2174: bool old_ct = false, resched = false;
2175:
2176: if (unlikely(sysctl_expire_nodest_conn(ipvs)) && cp->dest &&
2177: unlikely(!atomic_read(&cp->dest->weight))) {
2178: resched = true;
2179: old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);
2180: } else if (conn_reuse_mode &&
2181: is_new_conn_expected(cp, conn_reuse_mode)) {
2182: old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);
2183: if (!atomic_read(&cp->n_control)) {
2184: resched = true;
2185: } else {
2186: /* Do not reschedule controlling connection
2187: * that uses conntrack while it is still
2188: * referenced by controlled connection(s).
2189: */
2190: resched = !old_ct;
2191: }
2192: }
2193:
2194: if (resched) {
2195: if (!old_ct)
2196: cp->flags &= ~IP_VS_CONN_F_NFCT;
2197: if (!atomic_read(&cp->n_control))
2198: ip_vs_conn_expire_now(cp);
2199: __ip_vs_conn_put(cp);
2200: if (old_ct)
2201: return NF_DROP;
2202: cp = NULL;
2203: }
2204: }
2205:
2206: /* Check the server status */
2207: if (cp && cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {
2208: /* the destination server is not available */
2209: if (sysctl_expire_nodest_conn(ipvs)) {
2210: bool old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);
2211:
2212: if (!old_ct)
2213: cp->flags &= ~IP_VS_CONN_F_NFCT;
2214:
2215: ip_vs_conn_expire_now(cp);
2216: __ip_vs_conn_put(cp);
2217: if (old_ct)
2218: return NF_DROP;
2219: cp = NULL;
2220: } else {
2221: __ip_vs_conn_put(cp);
2222: return NF_DROP;
2223: }
2224: }
2225:
2226: if (unlikely(!cp)) {
2227: int v;
2228:
2229: if (!ip_vs_try_to_schedule(ipvs, af, skb, pd, &v, &cp, &iph))
2230: return v;
2231: }
2232:
2233: IP_VS_DBG_PKT(11, af, pp, skb, iph.off, "Incoming packet");
2234:
2235: ip_vs_in_stats(cp, skb);
2236: ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pd);
2237: if (cp->packet_xmit)
2238: ret = cp->packet_xmit(skb, cp, pp, &iph);
2239: /* do not touch skb anymore */
2240: else {
2241: IP_VS_DBG_RL("warning: packet_xmit is null");
2242: ret = NF_ACCEPT;
2243: }
2244:
2245: /* Increase its packet counter and check if it is needed
2246: * to be synchronized
2247: *
2248: * Sync connection if it is about to close to
2249: * encorage the standby servers to update the connections timeout
2250: *
2251: * For ONE_PKT let ip_vs_sync_conn() do the filter work.
2252: */
2253:
2254: if (cp->flags & IP_VS_CONN_F_ONE_PACKET)
2255: pkts = sysctl_sync_threshold(ipvs);
2256: else
2257: pkts = atomic_inc_return(&cp->in_pkts);
2258:
2259: if (ipvs->sync_state & IP_VS_STATE_MASTER)
2260: ip_vs_sync_conn(ipvs, cp, pkts);
2261: else if ((cp->flags & IP_VS_CONN_F_ONE_PACKET) && cp->control)
2262: /* increment is done inside ip_vs_sync_conn too */
2263: atomic_inc(&cp->control->in_pkts);
2264:
2265: ip_vs_conn_put(cp);
2266: return ret;
2267: }
SourceFile:net/netfilter/ipvs/ip_vs_core.c]
|
| 28/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 31914
output: 44
thoughts: 184
Thoughts: **Analyzing the IPVS Flow in Outbound IPvlan Traffic**
Okay, so I'm looking at how IPVS interacts with IPvlan, and there's something that's not quite clicking. The code in `ip_vs_in_hook` seems straightforward enough; it checks `skb->ipvs_property`. If that flag is set, it immediately returns `NF_ACCEPT`. This suggests the packet has already been processed by IPVS. That makes sense.
Now, I'm thinking about where this flag gets set. `ip_vs_send_or_cont` sets `skb->ipvs_property = 1`. So, if this function sets the flag, and the hook checks the flag and accepts, why do I see the packet re-entering the process? Something seems off here.
I'm starting to think `ipvlan` is somehow responsible for clearing or altering this crucial flag. So, I need to revisit the `ipvlan_process_v4_outbound` path. It calls `ip_local_out`. Does `ip_local_out` somehow reset `skb->ipvs_property`? Or perhaps the lower-level transmission functions within `ipvlan`, such as `ipvlan_queue_xmit` or `ipvlan_start_xmit`, are inadvertently interfering with the IPVS property. I need to dive into those functions to see if they're touching `skb->ipvs_property`. The mystery continues...
|
| 29/2 |
2026/06/02 00:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/net/ipvlan/ipvlan_core.c Name:ipvlan_queue_xmit]
Results: map[SourceCode: 675: int ipvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev)
676: {
677: struct ipvl_dev *ipvlan = netdev_priv(dev);
678: struct ipvl_port *port = ipvlan_port_get_rcu_bh(ipvlan->phy_dev);
679:
680: if (!port)
681: goto out;
682:
683: if (unlikely(!pskb_may_pull(skb, sizeof(struct ethhdr))))
684: goto out;
685:
686: switch(port->mode) {
687: case IPVLAN_MODE_L2:
688: return ipvlan_xmit_mode_l2(skb, dev);
689: case IPVLAN_MODE_L3:
690: #ifdef CONFIG_IPVLAN_L3S
691: case IPVLAN_MODE_L3S:
692: #endif
693: return ipvlan_xmit_mode_l3(skb, dev);
694: }
695:
696: /* Should not reach here */
697: WARN_ONCE(true, "%s called for mode = [%x]\n", __func__, port->mode);
698: out:
699: kfree_skb(skb);
700: return NET_XMIT_DROP;
701: }
SourceFile:drivers/net/ipvlan/ipvlan_core.c]
|
| 30/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 32921
output: 47
thoughts: 16
Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, and delivered as a first-person summary:
**Assessing IPvlan L3 Transmission Mode**
Right, let's dive straight in and scrutinize the `ipvlan_xmit_mode_l3` setting. I need to refresh my understanding of how this specific configuration impacts the overall data transmission process in IPvlan networks, particularly within the context of layer 3. I'm thinking about the potential implications for routing, MAC address handling, and the forwarding decisions the kernel will be making. I want to ensure I've got a solid grasp on any edge cases or performance bottlenecks this specific mode might introduce in different network topologies and with varying traffic patterns. It's crucial I consider the interplay between this setting and the underlying hardware capabilities of the network interfaces. I also want to make sure I understand how this mode impacts security and potential attack vectors if I implement this at a low-level. I am going to make sure to consider how this would affect me if I were to troubleshoot a complex network.
|
| 31/2 |
2026/06/02 00:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/net/ipvlan/ipvlan_core.c Name:ipvlan_xmit_mode_l3]
Results: map[SourceCode: 603: static int ipvlan_xmit_mode_l3(struct sk_buff *skb, struct net_device *dev)
604: {
605: const struct ipvl_dev *ipvlan = netdev_priv(dev);
606: void *lyr3h;
607: struct ipvl_addr *addr;
608: int addr_type;
609:
610: lyr3h = ipvlan_get_L3_hdr(ipvlan->port, skb, &addr_type);
611: if (!lyr3h)
612: goto out;
613:
614: if (!ipvlan_is_vepa(ipvlan->port)) {
615: addr = ipvlan_addr_lookup(ipvlan->port, lyr3h, addr_type, true);
616: if (addr) {
617: if (ipvlan_is_private(ipvlan->port)) {
618: consume_skb(skb);
619: return NET_XMIT_DROP;
620: }
621: ipvlan_rcv_frame(addr, &skb, true);
622: return NET_XMIT_SUCCESS;
623: }
624: }
625: out:
626: ipvlan_skb_crossing_ns(skb, ipvlan->phy_dev);
627: return ipvlan_process_outbound(skb);
628: }
SourceFile:drivers/net/ipvlan/ipvlan_core.c]
|
| 32/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 33668
output: 46
thoughts: 24
Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience:
**Analyzing `ipvlan_skb_crossing_ns`**
Okay, so I see `ipvlan_skb_crossing_ns` has been triggered. My first instinct is to dive into its purpose. I know this function is crucial in understanding how packets move between network namespaces within the IPvlan framework. I need to refresh my mental model of the cross-namespace communication path – likely involves some sort of bridging or tunneling logic, likely leveraging Netlink and potential changes to flow tables and routing. I’ll be checking for skb manipulations and address translation, along with any possible interaction with the networking stack’s core components like the routing and forwarding engine or connection tracking. My main interest is in any potential performance bottlenecks or subtle corner cases within this function that could lead to unexpected behavior. I'm immediately looking for how this function handles security implications like potential bridging of traffic between namespaces which shouldn’t have communication.
|
| 33/2 |
2026/06/02 00:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/net/ipvlan/ipvlan_core.c Name:ipvlan_skb_crossing_ns]
Results: map[SourceCode: 312: static void ipvlan_skb_crossing_ns(struct sk_buff *skb, struct net_device *dev)
313: {
314: bool xnet = true;
315:
316: if (dev)
317: xnet = !net_eq(dev_net(skb->dev), dev_net(dev));
318:
319: skb_scrub_packet(skb, xnet);
320: if (dev)
321: skb->dev = dev;
322: }
SourceFile:drivers/net/ipvlan/ipvlan_core.c]
|
| 34/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 34145
output: 39
thoughts: 24
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:
**Kernel Packet Scrubbing - Quick Assessment**
Alright, *skb_scrub_packet*... that's the function that's on my mind right now. I need to refresh my memory on what that thing actually *does*. I want to quickly evaluate its role within the larger context, so the first step, as always, is to dive right into the source and see what's happening internally, and how the functions work in concert. There's probably something I'm missing! Time to open it up and take a look.
|
| 35/2 |
2026/06/02 00:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/core/skbuff.c Name:skb_scrub_packet]
Results: map[SourceCode:6224: /**
6225: * skb_scrub_packet - scrub an skb
6226: *
6227: * @skb: buffer to clean
6228: * @xnet: packet is crossing netns
6229: *
6230: * skb_scrub_packet can be used after encapsulating or decapsulating a packet
6231: * into/from a tunnel. Some information have to be cleared during these
6232: * operations.
6233: * skb_scrub_packet can also be used to clean a skb before injecting it in
6234: * another namespace (@xnet == true). We have to clear all information in the
6235: * skb that could impact namespace isolation.
6236: */
6237: void skb_scrub_packet(struct sk_buff *skb, bool xnet)
6238: {
6239: skb->pkt_type = PACKET_HOST;
6240: skb->skb_iif = 0;
6241: skb->ignore_df = 0;
6242: skb_dst_drop(skb);
6243: skb_ext_reset(skb);
6244: nf_reset_ct(skb);
6245: nf_reset_trace(skb);
6246:
6247: #ifdef CONFIG_NET_SWITCHDEV
6248: skb->offload_fwd_mark = 0;
6249: skb->offload_l3_fwd_mark = 0;
6250: #endif
6251: ipvs_reset(skb);
6252:
6253: if (!xnet)
6254: return;
6255:
6256: skb->mark = 0;
6257: skb_clear_tstamp(skb);
6258: }
SourceFile:net/core/skbuff.c]
|
| 36/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 34914
output: 18
thoughts: 21
Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue:
**Investigating `ipvs_reset(skb)`**
Alright, that little `ipvs_reset(skb)` call just popped up in my head. Time to dig in. Let's make sure I'm following the flow correctly. Given the context, this has to be a critical point within the IPVS (IP Virtual Server) code. It implies some sort of state cleanup or potentially a reset of connection tracking information tied to that specific socket buffer, `skb`. I need to figure out the exact point it’s called to truly understand its role within the larger picture. I want to check for race conditions. If that’s not handled, I might have a security flaw. I need to refresh myself on the interactions, to see whether the sequence of calls is correct, and whether it’s handled within the right locking. Let’s see what's going on... I need to consider all the ways `skb` might be used or accessed after this point to ensure that any potential side effects are correctly managed. This is going to be about tracing the function back to the originating point and making sure I understand the why.
|
| 37/2 |
2026/06/02 00:32 |
tool |
grepper |
0m
Args: map[Expression:ipvs_reset]
Results: map[Output:include/linux/skbuff.h=5143=static inline void nf_reset_trace(struct sk_buff *skb)
--
include/linux/skbuff.h-5149-
include/linux/skbuff.h:5150:static inline void ipvs_reset(struct sk_buff *skb)
include/linux/skbuff.h-5151-{
--
net/core/skbuff.c=6237=void skb_scrub_packet(struct sk_buff *skb, bool xnet)
--
net/core/skbuff.c-6250-#endif
net/core/skbuff.c:6251: ipvs_reset(skb);
net/core/skbuff.c-6252-
--
net/xfrm/xfrm_interface_core.c=293=static void xfrmi_scrub_packet(struct sk_buff *skb, bool xnet)
--
net/xfrm/xfrm_interface_core.c-305-
net/xfrm/xfrm_interface_core.c:306: ipvs_reset(skb);
net/xfrm/xfrm_interface_core.c-307- secpath_reset(skb);
]
|
| 38/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 35535
output: 36
thoughts: 22
Thoughts: Here's my take on those thoughts:
**Analyzing `ipvs_reset` in the SKB Context**
Okay, so I'm diving into `ipvs_reset`, specifically within the `include/linux/skbuff.h` context. This instantly tells me we're dealing with how the IPVS code interacts with the socket buffer (skb) structures. The core function here, `ipvs_reset`, is, I presume, responsible for the cleanup or resetting of some IPVS-related data that might be associated with a socket buffer. I'm going to want to understand what kind of data it resets: Is it connection tracking information? NAT-related state? Counters? Or maybe something more fundamental to how the skb is handled within the IPVS system? My expertise is in IPVS, so that tells me where I'll need to drill in, but I'll need to see precisely *what* is being reset. From the filename I know this relates to the skb which is the fundamental data structure in the kernel for network packets. I'm anticipating that understanding this reset function is going to be key to debugging connection-related issues or even tracing the flow of packets through IPVS.
|
| 39/2 |
2026/06/02 00:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:include/linux/skbuff.h Name:ipvs_reset]
Results: map[SourceCode:5150: static inline void ipvs_reset(struct sk_buff *skb)
5151: {
5152: #if IS_ENABLED(CONFIG_IP_VS)
5153: skb->ipvs_property = 0;
5154: #endif
5155: }
SourceFile:include/linux/skbuff.h]
|
| 40/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 35963
output: 43
thoughts: 1754
Thoughts: **The IPVS-Ipvlan Packet Loop: A Deep Dive**
Okay, so here's the breakdown of this nasty kernel panic scenario I've just been looking at. It all starts with the interaction between IPVS and Ipvlan, which I can now see, can lead to a really ugly infinite loop.
My initial thought was that `ipvs_reset` clearing `skb->ipvs_property` was the key. We have `ipvlan_skb_crossing_ns` calling `skb_scrub_packet` which then calls `ipvs_reset`. This clears that property. So, `ipvlan_process_outbound` gets called, leading to `ip_local_out`, hitting `nf_hook_slow`, which is where `ip_vs_in_hook` gets involved. Because `skb->ipvs_property` is now zero, `ip_vs_in_hook` processes the packet again!
From there, it forwards the packet back into the system through `ip_vs_dr_xmit` and `ip_vs_send_or_cont`, hitting `NF_HOOK` again, which in turn calls `ip_output` -> `dev_queue_xmit` and back to `ipvlan_start_xmit`. And thus the loop begins!
I had to dig a bit deeper. I see `ipvlan_skb_crossing_ns` being called within `ipvlan_xmit_mode_l3`. This sets `skb->dev` to `ipvlan->phy_dev`. Ah, so then `ipvlan_process_v4_outbound` will use `ipvlan->phy_dev`. So `ip_local_out` is called in the network namespace of the `ipvlan->phy_dev`.
If the `ipvlan->phy_dev` and the ipvlan interface are in the same network namespace, then, we have a loop!
`ip_vs_send_or_cont` calls `NF_HOOK` and the `skb_dst(skb)->dev` is determined by the routing table. If the route points to the `ipvlan` device, `dst_output` will call `dev_queue_xmit` on the `ipvlan` device. This is the crucial point.
`ipvlan_start_xmit` then calls `ipvlan_queue_xmit` and from here, it calls `ipvlan_xmit_mode_l3`. And here the issue happens! `ipvlan_xmit_mode_l3` calls `ipvlan_skb_crossing_ns(skb, ipvlan->phy_dev)`. This clears `skb->ipvs_property` and sets `skb->dev = ipvlan->phy_dev`, and then we hit `ipvlan_process_outbound` again, and the routing kicks in once more. If the route keeps pointing to the `ipvlan` device, we're stuck in a vicious cycle.
Now it looks like this is the definitive loop:
1. `dev_queue_xmit(ipvlan_dev)`
2. `ipvlan_start_xmit` -> `ipvlan_queue_xmit` -> `ipvlan_xmit_mode_l3`
3. `ipvlan_skb_crossing_ns` clears `skb->ipvs_property` and sets `skb->dev = phy_dev`.
4. `ipvlan_process_v4_outbound` routes the packet, calling `ip_local_out`.
5. `ip_local_out` triggers `ip_vs_in_hook`.
6. `ip_vs_in_hook` matches the packet and calls `ip_vs_dr_xmit`.
7. `ip_vs_dr_xmit` routes the packet. If the route points to `ipvlan_dev`, it calls `dev_queue_xmit(ipvlan_dev)`.
8. Go back to 1.
Can an unprivileged user even set this up? Well, that's the scary part, I think I see a way.
Yes, in a user namespace:
1. Create a network namespace.
2. Create a `dummy` device (this will be `phy_dev`).
3. Create an `ipvlan` device on top of the `dummy` device, in L3 mode.
4. Assign IP addresses.
5. Set up an IPVS service and a destination. Crucially, the destination should route to the `ipvlan` device.
6. Send a packet that matches the IPVS service.
7. The
|
| 41/2 |
2026/06/02 00:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:drivers/net/ipvlan/ipvlan_main.c Name:ipvlan_link_new]
Results: map[SourceCode: 538: int ipvlan_link_new(struct net_device *dev, struct rtnl_newlink_params *params,
539: struct netlink_ext_ack *extack)
540: {
541: struct net *link_net = rtnl_newlink_link_net(params);
542: struct ipvl_dev *ipvlan = netdev_priv(dev);
543: struct nlattr **data = params->data;
544: struct nlattr **tb = params->tb;
545: struct ipvl_port *port;
546: struct net_device *phy_dev;
547: int err;
548: u16 mode = IPVLAN_MODE_L3;
549:
550: if (!tb[IFLA_LINK])
551: return -EINVAL;
552:
553: phy_dev = __dev_get_by_index(link_net, nla_get_u32(tb[IFLA_LINK]));
554: if (!phy_dev)
555: return -ENODEV;
556:
557: if (netif_is_ipvlan(phy_dev)) {
558: struct ipvl_dev *tmp = netdev_priv(phy_dev);
559:
560: phy_dev = tmp->phy_dev;
561: if (!ns_capable(dev_net(phy_dev)->user_ns, CAP_NET_ADMIN))
562: return -EPERM;
563: } else if (!netif_is_ipvlan_port(phy_dev)) {
564: /* Exit early if the underlying link is invalid or busy */
565: if (phy_dev->type != ARPHRD_ETHER ||
566: phy_dev->flags & IFF_LOOPBACK) {
567: netdev_err(phy_dev,
568: "Master is either lo or non-ether device\n");
569: return -EINVAL;
570: }
571:
572: if (netdev_is_rx_handler_busy(phy_dev)) {
573: netdev_err(phy_dev, "Device is already in use.\n");
574: return -EBUSY;
575: }
576: }
577:
578: ipvlan->phy_dev = phy_dev;
579: ipvlan->dev = dev;
580: ipvlan->sfeatures = IPVLAN_FEATURES;
581: if (!tb[IFLA_MTU])
582: ipvlan_adjust_mtu(ipvlan, phy_dev);
583: INIT_LIST_HEAD(&ipvlan->addrs);
584:
585: /* TODO Probably put random address here to be presented to the
586: * world but keep using the physical-dev address for the outgoing
587: * packets.
588: */
589: eth_hw_addr_set(dev, phy_dev->dev_addr);
590:
591: dev->priv_flags |= IFF_NO_RX_HANDLER;
592:
593: err = register_netdevice(dev);
594: if (err < 0)
595: return err;
596:
597: /* ipvlan_init() would have created the port, if required */
598: port = ipvlan_port_get_rtnl(phy_dev);
599: ipvlan->port = port;
600:
601: /* If the port-id base is at the MAX value, then wrap it around and
602: * begin from 0x1 again. This may be due to a busy system where lots
603: * of slaves are getting created and deleted.
604: */
605: if (port->dev_id_start == 0xFFFE)
606: port->dev_id_start = 0x1;
607:
608: /* Since L2 address is shared among all IPvlan slaves including
609: * master, use unique 16 bit dev-ids to differentiate among them.
610: * Assign IDs between 0x1 and 0xFFFE (used by the master) to each
611: * slave link [see addrconf_ifid_eui48()].
612: */
613: err = ida_alloc_range(&port->ida, port->dev_id_start, 0xFFFD,
614: GFP_KERNEL);
615: if (err < 0)
616: err = ida_alloc_range(&port->ida, 0x1, port->dev_id_start - 1,
617: GFP_KERNEL);
618: if (err < 0)
619: goto unregister_netdev;
620: dev->dev_id = err;
621:
622: /* Increment id-base to the next slot for the future assignment */
623: port->dev_id_start = err + 1;
624:
625: err = netdev_upper_dev_link(phy_dev, dev, extack);
626: if (err)
627: goto remove_ida;
628:
629: /* Flags are per port and latest update overrides. User has
630: * to be consistent in setting it just like the mode attribute.
631: */
632: if (data && data[IFLA_IPVLAN_FLAGS])
633: port->flags = nla_get_u16(data[IFLA_IPVLAN_FLAGS]);
634:
635: if (data && data[IFLA_IPVLAN_MODE])
636: mode = nla_get_u16(data[IFLA_IPVLAN_MODE]);
637:
638: err = ipvlan_set_port_mode(port, mode, extack);
639: if (err)
640: goto unlink_netdev;
641:
642: list_add_tail_rcu(&ipvlan->pnode, &port->ipvlans);
643: netif_stacked_transfer_operstate(phy_dev, dev);
644: return 0;
645:
646: unlink_netdev:
647: netdev_upper_dev_unlink(phy_dev, dev);
648: remove_ida:
649: ida_free(&port->ida, dev->dev_id);
650: unregister_netdev:
651: unregister_netdevice(dev);
652: return err;
653: }
SourceFile:drivers/net/ipvlan/ipvlan_main.c]
|
| 42/2 |
2026/06/02 00:32 |
llm |
expert |
0m
Model:
Tokens:
input: 40723
output: 24
thoughts: 1550
Thoughts: **My Assessment of the `ipvlan` and `ipvs` Stack Overflow**
Alright, let's break this down. My initial observation is that this `dummy` device, characterized as `ARPHRD_ETHER` but not `IFF_LOOPBACK`, allows us to create an `ipvlan` interface on top of it. That's the setup. Now, the vulnerability.
* This is definitely a stack overflow. It triggers a kernel panic, hitting that stack guard page.
* The good news (or bad, depending on your perspective) is that an unprivileged user can trigger this. They just need to create a user namespace and a network namespace, configure the `dummy` device, then `ipvlan`, and finally, `ipvs`. No exotic hardware is required.
* The impact is a Denial of Service. The kernel panics.
Now, the crucial question: can we escalate privileges? Typically, stack overflows with guard pages are a dead end for privilege escalation. The guard page exists *specifically* to prevent memory corruption and trigger a panic instead. The page fault interrupts before anything nefarious can happen. We're protected. I checked the stack frame size of the vulnerable function calls, `ipvlan_start_xmit` through to `__netdev_start_xmit`. It totals at most 1-2 KB per iteration. The guard page is 4KB. Unless a single function allocates a huge stack array, there's no way to skip the guard page; it will be hit. This means no memory corruption, thus, no privilege escalation. It's a DoS.
Let's quickly check kernel configuration requirements: `CONFIG_IP_VS` and `CONFIG_IPVLAN` are commonly enabled as modules in major distributions. User namespaces are enabled by default. This confirms this is a very solid local DoS vulnerability.
Can we trigger this remotely? If an attacker sends a packet to a machine with this *specific* configuration – an `ipvlan` interface with `ipvs` configured to route *back* to itself – then yes, they can trigger the loop. However, that configuration is an *unintentional* routing loop. Any competent administrator would never intentionally do that. But if, by some unlucky circumstance, an admin *misconfigures* a system in this way, *then* it's remotely triggerable. The primary threat remains local, unprivileged users setting up the configuration in a user namespace.
So here is how it shakes out:
* **Exploitable:** False (guard page prevents exploitation).
* **Denial of Service:** True (kernel panic).
* **Accessible From Unprivileged Processes:** True (via user namespaces).
* **Accessible From User Namespaces:** True (it's user namespace related).
* **VM Guest Trigger:** False (This is a local kernel bug, so it doesn't affect the host).
* **VM Host Trigger in The Confidential Computing Context:** False (host-to-guest is not possible).
* **Ethernet Network Trigger:** False (requires a highly unusual, administrator-infeasible self-looping configuration).
* **Other Remote Trigger:** False (not triggered by common configurations).
* **Peripheral Trigger:** False.
* **Malicious Filesystem Trigger:** False.
I went back and checked that `ipvs` uses `.netnsok = true` in `ip_vs_genl_family`, and `ip_vs_sockopts` registers using `nf_register_sockopt`, which further confirms that it can be configured in the user namespace, and that it is indeed possible for an unprivileged user to trigger it.
|
| 43/2 |
2026/06/02 00:33 |
tool |
grepper |
0m
Args: map[Expression:nf_register_sockopt.*ip_vs]
Results: map[Output:net/netfilter/ipvs/ip_vs_ctl.c=5165=int __init ip_vs_register_nl_ioctl(void)
--
net/netfilter/ipvs/ip_vs_ctl.c-5168-
net/netfilter/ipvs/ip_vs_ctl.c:5169: ret = nf_register_sockopt(&ip_vs_sockopts);
net/netfilter/ipvs/ip_vs_ctl.c-5170- if (ret) {
]
|
| 44/2 |
2026/06/02 00:33 |
llm |
expert |
0m
Model:
Tokens:
input: 43226
output: 45
thoughts: 12
Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience:
**Analyzing the `ip_vs_sockopts` Situation**
Alright, time to dig into `ip_vs_sockopts`. That's where the interesting stuff usually lies when dealing with IP Virtual Server and socket options. My immediate thought is, "What specifically are we trying to accomplish here?" Knowing the use case is paramount. Are we looking at performance tweaks, security considerations, or perhaps compatibility issues with a specific application or network configuration?
I'll need to remember to consider the kernel version and relevant modules involved. Different versions of `ipvs` and the kernel itself can behave differently, and that's often where the subtle, yet critical, nuances hide. I also want to immediately check any documented caveats and known bugs associated with various socket option settings, and their interaction with IPVS.
My mental checklist starts with: Are we concerned about things like `TCP_NODELAY`, `SO_REUSEADDR`, `SO_KEEPALIVE`, or even custom socket options? The implications of those, particularly in a high-concurrency, load-balanced environment, are worth a very close look. I want to rule out any potential for unexpected connection behaviors, especially in the areas of resource contention, connection re-use, and potential for lingering connections.
A quick review of the source code, if available, would be incredibly valuable right now. I'll mentally map out the key functions that interact with socket options within the `ipvs` code, and start forming hypotheses about how these options are processed and applied to the connections that `ipvs` manages. Understanding how the netfilter hooks tie into this, and any potential for interaction with other network stack elements, is critical. Any interactions with conntrack would be particularly important here.
Ultimately, I need to understand if the configuration and the use of the `ip_vs_sockopts` are correctly optimized for the specific workloads we're running. And whether we're seeing optimal performance, resource utilization, and overall stability within the system. Let’s get started.
|
| 45/2 |
2026/06/02 00:33 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/ipvs/ip_vs_ctl.c Name:ip_vs_sockopts]
Results: map[SourceCode:3799: static struct nf_sockopt_ops ip_vs_sockopts = {
3800: .pf = PF_INET,
3801: .set_optmin = IP_VS_BASE_CTL,
3802: .set_optmax = IP_VS_SO_SET_MAX+1,
3803: .set = do_ip_vs_set_ctl,
3804: .get_optmin = IP_VS_BASE_CTL,
3805: .get_optmax = IP_VS_SO_GET_MAX+1,
3806: .get = do_ip_vs_get_ctl,
3807: .owner = THIS_MODULE,
3808: };
SourceFile:net/netfilter/ipvs/ip_vs_ctl.c]
|
| 46/2 |
2026/06/02 00:33 |
llm |
expert |
0m
Model:
Tokens:
input: 43959
output: 48
thoughts: 51
Thoughts: Okay, here's my interpretation of those thoughts, speaking as an expert:
**Investigating Network Namespace Scope and Capability Checks**
Hmm, I'm just quickly trying to clarify something about the `nf_register_sockopt` function. I *thought* initially that this would be limited to the `init_net` namespace, but then I remembered, no, the `nf_sockopt_ops` structure is actually meant to operate across all network namespaces. That makes sense, keeps things consistent.
But now I need to dig a little deeper. I'm wondering if, within the `do_ip_vs_set_ctl` function, we're actually implementing some kind of capability check. That would be crucial for security. We wouldn't want just any process to be able to manipulate these options across network namespaces. I really need to verify if there's sufficient authorization in place.
|
| 47/2 |
2026/06/02 00:33 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/ipvs/ip_vs_ctl.c Name:do_ip_vs_set_ctl]
Results: map[SourceCode:3319: static int
3320: do_ip_vs_set_ctl(struct sock *sk, int cmd, sockptr_t ptr, unsigned int len)
3321: {
3322: struct net *net = sock_net(sk);
3323: int ret;
3324: unsigned char arg[MAX_SET_ARGLEN];
3325: struct ip_vs_service_user *usvc_compat;
3326: struct ip_vs_service_user_kern usvc;
3327: struct ip_vs_service *svc;
3328: struct ip_vs_dest_user *udest_compat;
3329: struct ip_vs_dest_user_kern udest;
3330: struct netns_ipvs *ipvs = net_ipvs(net);
3331:
3332: BUILD_BUG_ON(sizeof(arg) > 255);
3333: if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
3334: return -EPERM;
3335:
3336: if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX)
3337: return -EINVAL;
3338: if (len != set_arglen[CMDID(cmd)]) {
3339: IP_VS_DBG(1, "set_ctl: len %u != %u\n",
3340: len, set_arglen[CMDID(cmd)]);
3341: return -EINVAL;
3342: }
3343:
3344: if (copy_from_sockptr(arg, ptr, len) != 0)
3345: return -EFAULT;
3346:
3347: /* Handle daemons since they have another lock */
3348: if (cmd == IP_VS_SO_SET_STARTDAEMON ||
3349: cmd == IP_VS_SO_SET_STOPDAEMON) {
3350: struct ip_vs_daemon_user *dm = (struct ip_vs_daemon_user *)arg;
3351:
3352: if (cmd == IP_VS_SO_SET_STARTDAEMON) {
3353: struct ipvs_sync_daemon_cfg cfg;
3354:
3355: memset(&cfg, 0, sizeof(cfg));
3356: ret = -EINVAL;
3357: if (strscpy(cfg.mcast_ifn, dm->mcast_ifn,
3358: sizeof(cfg.mcast_ifn)) <= 0)
3359: return ret;
3360: cfg.syncid = dm->syncid;
3361: ret = start_sync_thread(ipvs, &cfg, dm->state);
3362: } else {
3363: ret = stop_sync_thread(ipvs, dm->state);
3364: }
3365: return ret;
3366: }
3367:
3368: mutex_lock(&ipvs->service_mutex);
3369: if (cmd == IP_VS_SO_SET_FLUSH) {
3370: /* Flush the virtual service */
3371: ret = ip_vs_flush(ipvs, false);
3372: goto out_unlock;
3373: } else if (cmd == IP_VS_SO_SET_TIMEOUT) {
3374: /* Set timeout values for (tcp tcpfin udp) */
3375: ret = ip_vs_set_timeout(ipvs, (struct ip_vs_timeout_user *)arg);
3376: goto out_unlock;
3377: } else if (!len) {
3378: /* No more commands with len == 0 below */
3379: ret = -EINVAL;
3380: goto out_unlock;
3381: }
3382:
3383: usvc_compat = (struct ip_vs_service_user *)arg;
3384: udest_compat = (struct ip_vs_dest_user *)(usvc_compat + 1);
3385:
3386: /* We only use the new structs internally, so copy userspace compat
3387: * structs to extended internal versions */
3388: ip_vs_copy_usvc_compat(&usvc, usvc_compat);
3389: ip_vs_copy_udest_compat(&udest, udest_compat);
3390:
3391: if (cmd == IP_VS_SO_SET_ZERO) {
3392: /* if no service address is set, zero counters in all */
3393: if (!usvc.fwmark && !usvc.addr.ip && !usvc.port) {
3394: ret = ip_vs_zero_all(ipvs);
3395: goto out_unlock;
3396: }
3397: }
3398:
3399: if ((cmd == IP_VS_SO_SET_ADD || cmd == IP_VS_SO_SET_EDIT) &&
3400: strnlen(usvc.sched_name, IP_VS_SCHEDNAME_MAXLEN) ==
3401: IP_VS_SCHEDNAME_MAXLEN) {
3402: ret = -EINVAL;
3403: goto out_unlock;
3404: }
3405:
3406: /* Check for valid protocol: TCP or UDP or SCTP, even for fwmark!=0 */
3407: if (usvc.protocol != IPPROTO_TCP && usvc.protocol != IPPROTO_UDP &&
3408: usvc.protocol != IPPROTO_SCTP) {
3409: pr_err("set_ctl: invalid protocol: %d %pI4:%d\n",
3410: usvc.protocol, &usvc.addr.ip,
3411: ntohs(usvc.port));
3412: ret = -EFAULT;
3413: goto out_unlock;
3414: }
3415:
3416: /* Lookup the exact service by <protocol, addr, port> or fwmark */
3417: rcu_read_lock();
3418: if (usvc.fwmark == 0)
3419: svc = __ip_vs_service_find(ipvs, usvc.af, usvc.protocol,
3420: &usvc.addr, usvc.port);
3421: else
3422: svc = __ip_vs_svc_fwm_find(ipvs, usvc.af, usvc.fwmark);
3423: rcu_read_unlock();
3424:
3425: if (cmd != IP_VS_SO_SET_ADD
3426: && (svc == NULL || svc->protocol != usvc.protocol)) {
3427: ret = -ESRCH;
3428: goto out_unlock;
3429: }
3430:
3431: switch (cmd) {
3432: case IP_VS_SO_SET_ADD:
3433: if (svc != NULL)
3434: ret = -EEXIST;
3435: else
3436: ret = ip_vs_add_service(ipvs, &usvc, &svc);
3437: break;
3438: case IP_VS_SO_SET_EDIT:
3439: ret = ip_vs_edit_service(svc, &usvc);
3440: break;
3441: case IP_VS_SO_SET_DEL:
3442: ret = ip_vs_del_service(svc);
3443: if (!ret)
3444: goto out_unlock;
3445: break;
3446: case IP_VS_SO_SET_ZERO:
3447: ret = ip_vs_zero_service(svc);
3448: break;
3449: case IP_VS_SO_SET_ADDDEST:
3450: ret = ip_vs_add_dest(svc, &udest);
3451: break;
3452: case IP_VS_SO_SET_EDITDEST:
3453: ret = ip_vs_edit_dest(svc, &udest);
3454: break;
3455: case IP_VS_SO_SET_DELDEST:
3456: ret = ip_vs_del_dest(svc, &udest);
3457: break;
3458: default:
3459: WARN_ON_ONCE(1);
3460: ret = -EINVAL;
3461: break;
3462: }
3463:
3464: out_unlock:
3465: mutex_unlock(&ipvs->service_mutex);
3466: return ret;
3467: }
SourceFile:net/netfilter/ipvs/ip_vs_ctl.c]
|
| 48/2 |
2026/06/02 00:33 |
llm |
expert |
0m
Model:
Tokens:
input: 46738
output: 66
thoughts: 1137
Thoughts: **My Analysis of the IPVS/IPVLAN Kernel Panic Vulnerability**
Okay, so I've been dissecting this kernel bug. The code snippet immediately jumps out – that `ns_capable` check is the key. The kernel *does* verify `CAP_NET_ADMIN` using `ns_capable` before allowing IPVS configuration. That's the gatekeeper. So an unprivileged user can't directly configure IPVS in the initial namespace. But, and this is crucial, they *can* create a user namespace and get `CAP_NET_ADMIN` within it. That opens the door to configuring IPVS.
The question then becomes, can an unprivileged user force a system with IPVS preconfigured (presumably by an admin) to trigger the vulnerability? Could they trigger an auto-load of IPVS? It looks like it doesn't matter since the system can be configured. The prompt specifies this check is assuming that user namespaces are *not* accessible for the unprivileged user, so in that case, the answer would be False, otherwise True.
Then, there is the assumption that the system administrator has created a routing loop with an ipvlan device. This configuration would be an unusual setup, and thus would not be a typical configuration. This specific routing loop misconfiguration will lead to a Denial of Service, but it's not a common or default setup. So I'll mark "Ethernet Network Trigger" as False, because it's highly unlikely.
Now, let's nail down the results of this analysis, considering all the points:
* **Exploitable: False**. The stack overflow hits the stack guard page, preventing privilege escalation. It's a DoS, but not an exploit in the traditional sense.
* **Denial of Service: True**. Kernel panic due to the stack overflow. No doubt about it.
* **Accessible From Unprivileged Processes: False**. Requires `CAP_NET_ADMIN`, which an unprivileged user doesn't have in the initial namespace.
* **Accessible From User Namespaces: True**. User namespaces grant `CAP_NET_ADMIN`.
* **VM Guest Trigger: False**
* **VM Host Trigger in The Confidential Computing Context: False**
* **Ethernet Network Trigger: False**. This loop is a highly specific, unlikely misconfiguration.
* **Other Remote Trigger: False**
* **Peripheral Trigger: False**
* **Malicious Filesystem Trigger: False**
Alright, let's summarize the root cause, in detail. It's a stack overflow. Specifically, it's an infinite loop between `ipvlan` and IPVS. When an L3 mode packet goes through the `ipvlan` device, `ipvlan_xmit_mode_l3` is called which, in turn, calls `ipvlan_skb_crossing_ns`. This function scrubs the packet, including clearing the `skb->ipvs_property` flag via `ipvs_reset(skb)`. The packet then hits `ip_local_out`, triggering netfilter hooks, and `ip_vs_in_hook` (registered by IPVS) is called. Because the flag was cleared, IPVS processes the packet again. This happens if the destination points back to the same `ipvlan` device. This repeated processing happens when there is an IPVS service configured in Direct Routing (DR) mode that routes to the same `ipvlan` device, which triggers `dev_queue_xmit` again and creates the loop. The result is the stack overflowing. The overflow continues in this order `ipvlan_start_xmit` -> `ipvlan_xmit_mode_l3` -> `ip_local_out` -> `ip_vs_in_hook` -> `ip_vs_dr_xmit` -> `dev_queue_xmit` -> `ipvlan_start_xmit`.
*Exploitability*: This crash is not exploitable because the stack guard page is hit which causes a page fault.
*Accessibility*: Configuring this requires setting up an `ipvlan` device and IPVS rules and needs `CAP_NET_ADMIN`. So it's accessible from user namespaces.
*Network Trigger*: This requires a very specific misconfiguration on the target system. An unusual setup.
That's my final assessment. I'm going to run `set-results`.
|
| 49/2 |
2026/06/02 00:33 |
tool |
set-results |
0m
Args: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:false UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
Results: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:false UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
|
| 50/2 |
2026/06/02 00:33 |
llm |
expert |
0m
Model:
Tokens:
input: 48947
output: 706
thoughts: 13
Thoughts: Okay, here's the summary, rendered as a first-person thought process, aimed at an expert audience:
**Finalizing the Response**
Alright, the data's been crunched, the analysis is complete, and the interpretation has been rigorously checked. Everything’s in place, the variables have been accounted for, and any potential caveats have been addressed. Now it’s time to move beyond the internal review and prepare the final response. It's the point where I synthesize everything into a clear, concise, and defensible conclusion. No room for ambiguity here; this is the culmination of the process, the definitive statement based on solid evidence. I'm ready to present the final findings.
|
| 51/1 |
2026/06/02 00:33 |
action |
format-explanation |
0m
Results: map[Explanation:The bug is a stack overflow caused by an infinite recursion loop in the network
stack involving `ipvlan` and `ipvs` (IP Virtual Server).
### Root Cause Analysis
When a packet is transmitted through an `ipvlan` device configured in L3 mode,
the driver calls `ipvlan_xmit_mode_l3()`, which in turn calls
`ipvlan_skb_crossing_ns()`. This function scrubs the socket buffer (`skb`) by
calling `skb_scrub_packet()`, which clears various state flags, including the
`skb->ipvs_property` flag via `ipvs_reset(skb)`.
After scrubbing, the packet is routed and passed to `ip_local_out()`, which
triggers the `NF_INET_LOCAL_OUT` netfilter hooks. IPVS registers its
`ip_vs_in_hook()` at this exact hook. Normally, IPVS avoids processing the same
packet multiple times by checking if `skb->ipvs_property` is set. However,
because `ipvlan` just cleared this flag, IPVS fails to recognize that the packet
was already processed and processes it again.
If the packet matches an IPVS service configured in Direct Routing (DR) mode,
IPVS will route the packet to its destination (`ip_vs_dr_xmit()`). If the
routing table directs the packet back to the same `ipvlan` device, the packet is
queued to the `ipvlan` device again via `dev_queue_xmit()`.
This creates an infinite recursion loop:
`ipvlan_start_xmit` -> `ipvlan_xmit_mode_l3` -> `ip_local_out` ->
`ip_vs_in_hook` -> `ip_vs_dr_xmit` -> `dev_queue_xmit` -> `ipvlan_start_xmit`
...
The recursion continues until the kernel stack overflows and hits the stack
guard page, resulting in a kernel panic.
### Security Impact
* **Exploitable:** **False**. The stack overflow deterministically hits the 4KB
stack guard page (as seen in the `Oops: stack guard page` report). The guard
page triggers a page fault and halts the kernel before any adjacent memory can
be corrupted, preventing privilege escalation or arbitrary code execution.
* **Denial Of Service:** **True**. The bug reliably causes a kernel panic,
leading to a complete system crash.
* **Accessible From Unprivileged Processes:** **False**. Setting up the required
`ipvlan` device and IPVS rules requires `CAP_NET_ADMIN` privileges in the
network namespace.
* **Accessible From User Namespaces:** **True**. Both `ipvlan` devices (e.g., on
top of a `dummy` device) and IPVS can be fully configured inside an unprivileged
user namespace. A local attacker can create a new user/network namespace,
acquire `CAP_NET_ADMIN`, set up the looping configuration, and send a single
packet to crash the host system.
* **Network / Remote Triggers:** **False**. Triggering the bug remotely would
require the target system to already have this specific, self-looping
misconfiguration set up by an administrator. Since this configuration inherently
breaks networking for the involved IPs and serves no legitimate purpose, it is
not a realistic remote attack vector.]
|