| Seq | Timestamp | Type | Name | Duration |
|---|---|---|---|---|
| 0/0 | 2026/09/06 05:01 | flow | patch-triage |
0mArgs:null Results: {
"EnableConfigs": [
"NET_IP_TUNNEL",
"NET_IPGRE",
"NET_IPIP",
"NET_FOU_IP_TUNNELS"
],
"FocusSymbols": [
"ip_tunnel_xmit",
"ip_md_tunnel_xmit",
"tnl_update_pmtu"
],
"KMSANReasoning": "The patch addresses data races and PMTU/headroom calculations in IPv4 tunnel transmission (ip_tunnel_xmit and tnl_update_pmtu). Specifically:\n1. It snapshots `tunnel-\u003eencap` into a stack variable `ipencap` using `data_race()` to prevent concurrent modification by `ipgre_changelink()`.\n2. It accounts for `encap_hlen` in `tnl_update_pmtu` and defers calling `ip_tunnel_encap()` until after skb headroom is expanded with `skb_cow_head()`.\n\nRegarding sanitizers:\n- Memory safety bugs related to buffer headroom, skb bounds, and use-after-free are covered by KASAN.\n- Concurrency issues and data races are targeted by KCSAN/LOCKDEP.\n- The local variable `ipencap` is fully initialized via structure assignment before any read, `encap_hlen` is an integer initialized with the return value of `ip_encap_hlen()`, and no kernel memory is copied to user space. There is no risk of uninitialized memory reads or information leaks.\n\nTherefore, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false,
"Reasoning": "The patch modifies PMTU calculation and tunnel encapsulation handling during packet transmission in the IP tunneling subsystem (net/ipv4/ip_tunnel.c). It snapshots the tunnel encapsulation configuration to prevent data races during concurrent changelink operations, defers encapsulation in ip_tunnel_xmit, and accounts for encap header length in PMTU updates. These changes affect reachable core networking paths accessible via virtual tunnel devices and netlink configuration.",
"WorthFuzzing": true
} |
| 1/1 | 2026/09/06 05:01 | action | read-patch-diff |
0mArgs:null Results: {
"PatchDiff": "commit 50193a517faf720149ee924eb5dab7e1eccaf706\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Sun Sep 6 05:01:08 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c\nindex 9d114bd575f92..447b435b10cca 100644\n--- a/net/ipv4/ip_tunnel.c\n+++ b/net/ipv4/ip_tunnel.c\n@@ -512,14 +512,15 @@ EXPORT_SYMBOL_GPL(ip_tunnel_encap_setup);\n static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,\n \t\t\t struct rtable *rt, __be16 df,\n \t\t\t const struct iphdr *inner_iph,\n-\t\t\t int tunnel_hlen, __be32 dst, bool md)\n+\t\t\t int tunnel_hlen, __be32 dst, bool md,\n+\t\t\t int encap_hlen)\n {\n \tstruct ip_tunnel *tunnel = netdev_priv(dev);\n \tint pkt_size;\n \tint mtu;\n \n \ttunnel_hlen = md ? tunnel_hlen : tunnel-\u003ehlen;\n-\tpkt_size = skb-\u003elen - tunnel_hlen;\n+\tpkt_size = skb-\u003elen + encap_hlen - tunnel_hlen;\n \tpkt_size -= dev-\u003etype == ARPHRD_ETHER ? dev-\u003ehard_header_len : 0;\n \n \tif (df) {\n@@ -629,7 +630,7 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n \tif (test_bit(IP_TUNNEL_DONT_FRAGMENT_BIT, key-\u003etun_flags))\n \t\tdf = htons(IP_DF);\n \tif (tnl_update_pmtu(dev, skb, rt, df, inner_iph, tunnel_hlen,\n-\t\t\t key-\u003eu.ipv4.dst, true)) {\n+\t\t\t key-\u003eu.ipv4.dst, true, 0)) {\n \t\tip_rt_put(rt);\n \t\tgoto tx_error;\n \t}\n@@ -671,6 +672,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n {\n \tstruct ip_tunnel *tunnel = netdev_priv(dev);\n \tstruct ip_tunnel_info *tun_info = NULL;\n+\tstruct ip_tunnel_encap ipencap;\n \tconst struct iphdr *inner_iph;\n \tunsigned int max_headroom;\t/* The extra header space needed */\n \tstruct rtable *rt = NULL;\t\t/* Route to the other host */\n@@ -680,6 +682,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n \tbool md = false;\n \tbool connected;\n \tint err_count;\n+\tint encap_hlen;\n \tu8 tos, ttl;\n \t__be32 dst;\n \t__be16 df;\n@@ -765,7 +768,10 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n \t\t\t tunnel-\u003enet, READ_ONCE(tunnel-\u003eparms.link),\n \t\t\t tunnel-\u003efwmark, skb_get_hash(skb), 0);\n \n-\tif (ip_tunnel_encap(skb, \u0026tunnel-\u003eencap, \u0026protocol, \u0026fl4) \u003c 0)\n+\t/* Snapshot encap; ipgre_changelink() can update it concurrently. */\n+\tipencap = data_race(tunnel-\u003eencap);\n+\tencap_hlen = ip_encap_hlen(\u0026ipencap);\n+\tif (encap_hlen \u003c 0)\n \t\tgoto tx_error;\n \n \tif (connected \u0026\u0026 md) {\n@@ -803,7 +809,8 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n \tif (payload_protocol == htons(ETH_P_IP) \u0026\u0026 !tunnel-\u003eignore_df)\n \t\tdf |= (inner_iph-\u003efrag_off \u0026 htons(IP_DF));\n \n-\tif (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false)) {\n+\tif (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false,\n+\t\t\t encap_hlen)) {\n \t\tip_rt_put(rt);\n \t\tgoto tx_error;\n \t}\n@@ -834,7 +841,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n \t}\n \n \tmax_headroom = LL_RESERVED_SPACE(rt-\u003edst.dev) + sizeof(struct iphdr)\n-\t\t\t+ rt-\u003edst.header_len + ip_encap_hlen(\u0026tunnel-\u003eencap);\n+\t\t\t+ rt-\u003edst.header_len + encap_hlen;\n \n \tif (skb_cow_head(skb, max_headroom)) {\n \t\tip_rt_put(rt);\n@@ -845,6 +852,11 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n \n \tip_tunnel_adj_headroom(dev, max_headroom);\n \n+\tif (ip_tunnel_encap(skb, \u0026ipencap, \u0026protocol, \u0026fl4) \u003c 0) {\n+\t\tip_rt_put(rt);\n+\t\tgoto tx_error;\n+\t}\n+\n \tiptunnel_xmit(NULL, rt, skb, fl4.saddr, fl4.daddr, protocol, tos, ttl,\n \t\t df, !net_eq(tunnel-\u003enet, dev_net(dev)), 0);\n \treturn;\n"
} |
| 2/1 | 2026/09/06 05:01 | agent | patch-evaluator |
0mModel:core Args: null Results: {
"EnableConfigs": [
"NET_IP_TUNNEL",
"NET_IPGRE",
"NET_IPIP",
"NET_FOU_IP_TUNNELS"
],
"FocusSymbols": [
"ip_tunnel_xmit",
"ip_md_tunnel_xmit",
"tnl_update_pmtu"
],
"Reasoning": "The patch modifies PMTU calculation and tunnel encapsulation handling during packet transmission in the IP tunneling subsystem (net/ipv4/ip_tunnel.c). It snapshots the tunnel encapsulation configuration to prevent data races during concurrent changelink operations, defers encapsulation in ip_tunnel_xmit, and accounts for encap header length in PMTU updates. These changes affect reachable core networking paths accessible via virtual tunnel devices and netlink configuration.",
"WorthFuzzing": true
}Instruction: You are an expert Linux kernel maintainer and security engineer.
Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller.
IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on internal assumptions. You must actively use your code access
tools to inspect the actual source code, callers, and surrounding context.
================================================================================
1. CORE TRIAGE PHILOSOPHY
================================================================================
The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs,
and newly triggered assertions introduced by the patch series.
- REACHABILITY IS THE PRIMARY GATE:
Fuzzing can only discover bugs in code that can actually execute in standard virtualized
environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap).
If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed,
regardless of whether it adds assertions or complex logic.
- DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS:
Patch authors routinely label changes as "cleanups", "refactorings", or state
"No functional change intended". Do NOT take these claims at face value.
Code refactorings that rearrange logic, introduce helper functions, or alter state management
in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs.
If reachable executable code is modified or refactored, it MUST be fuzzed.
- NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED:
When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON*, VM_WARN_ON*,
BUG_ON*, lockdep_assert*) in reachable code paths, it enforces new or stricter invariants.
Even if the author believes the invariant always holds, fuzzing is essential to verify whether
an unusual sequence of operations can violate it.
================================================================================
2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA)
================================================================================
Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories:
- Non-kernel and non-executable changes:
* Modifications to Documentation/, comments, or spelling fixes.
* User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/)
that do not affect the compiled kernel image (vmlinux) or kernel modules.
* Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints
that do not alter control flow or data structures.
* Build system or Kconfig changes that do not alter compiled C logic.
- Structurally unreachable hardware:
* Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed,
ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU.
- Unreachable execution paths:
* Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during
physical PCI hot-unplug or manual sysfs driver unbinding.
* Code paths exclusive to architectures other than the target architecture.
================================================================================
3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA)
================================================================================
Return WorthFuzzing=true whenever the patch touches reachable executable code, including:
- Core Subsystems:
* Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/),
BPF, scheduler, core networking, VFS, or syscall handling.
- Refactorings and Code Cleanups:
* Any restructuring of reachable data structures, helper abstractions, or algorithm flows.
- Runtime Assertions and Defensive Checks:
* Any introduction or alteration of assertions (WARN_ON*, VM_WARN_ON*, BUG_ON*, etc.) in reachable paths.
- Reachable Drivers and Protocols:
* Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.).
================================================================================
4. EXTRACTING FocusSymbols (PREVENTING DILUTION)
================================================================================
When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer:
- AVOID UBIQUITOUS LIFECYCLE HOT-PATHS:
Do NOT list generic, ubiquitous functions called by almost every program in the corpus
(including, but not limited to: general memory allocators and deallocators, page fault
and trap handlers, or core synchronization primitives; this is not an exhaustive list).
Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused",
which severely dilutes fuzzing effort away from the actual changes.
- TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS:
List functions that specifically implement the logic being added or altered, or direct API entrypoints
for the subsystem feature under review.
- HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h):
Compiler-inlined static functions (such as static inlines in mm/*.h or include/linux/*.h) lack
distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters.
If the changes are primarily in static inline helpers, identify non-static, feature-specific caller
functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers).
================================================================================
5. IDENTIFYING EnableConfigs
================================================================================
Identify any specific CONFIG_ options required to properly compile and reach the modified code:
- Inspect Kconfig files and #ifdef guards; do not make assumptions.
- Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed.
- Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
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: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit 50193a517faf720149ee924eb5dab7e1eccaf706
Author: syz-cluster <triage@syzkaller.com>
Date: Sun Sep 6 05:01:08 2026 +0000
syz-cluster: applied patch under review
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 9d114bd575f92..447b435b10cca 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -512,14 +512,15 @@ EXPORT_SYMBOL_GPL(ip_tunnel_encap_setup);
static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
struct rtable *rt, __be16 df,
const struct iphdr *inner_iph,
- int tunnel_hlen, __be32 dst, bool md)
+ int tunnel_hlen, __be32 dst, bool md,
+ int encap_hlen)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
int pkt_size;
int mtu;
tunnel_hlen = md ? tunnel_hlen : tunnel->hlen;
- pkt_size = skb->len - tunnel_hlen;
+ pkt_size = skb->len + encap_hlen - tunnel_hlen;
pkt_size -= dev->type == ARPHRD_ETHER ? dev->hard_header_len : 0;
if (df) {
@@ -629,7 +630,7 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
if (test_bit(IP_TUNNEL_DONT_FRAGMENT_BIT, key->tun_flags))
df = htons(IP_DF);
if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, tunnel_hlen,
- key->u.ipv4.dst, true)) {
+ key->u.ipv4.dst, true, 0)) {
ip_rt_put(rt);
goto tx_error;
}
@@ -671,6 +672,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
{
struct ip_tunnel *tunnel = netdev_priv(dev);
struct ip_tunnel_info *tun_info = NULL;
+ struct ip_tunnel_encap ipencap;
const struct iphdr *inner_iph;
unsigned int max_headroom; /* The extra header space needed */
struct rtable *rt = NULL; /* Route to the other host */
@@ -680,6 +682,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
bool md = false;
bool connected;
int err_count;
+ int encap_hlen;
u8 tos, ttl;
__be32 dst;
__be16 df;
@@ -765,7 +768,10 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
tunnel->net, READ_ONCE(tunnel->parms.link),
tunnel->fwmark, skb_get_hash(skb), 0);
- if (ip_tunnel_encap(skb, &tunnel->encap, &protocol, &fl4) < 0)
+ /* Snapshot encap; ipgre_changelink() can update it concurrently. */
+ ipencap = data_race(tunnel->encap);
+ encap_hlen = ip_encap_hlen(&ipencap);
+ if (encap_hlen < 0)
goto tx_error;
if (connected && md) {
@@ -803,7 +809,8 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
if (payload_protocol == htons(ETH_P_IP) && !tunnel->ignore_df)
df |= (inner_iph->frag_off & htons(IP_DF));
- if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false)) {
+ if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false,
+ encap_hlen)) {
ip_rt_put(rt);
goto tx_error;
}
@@ -834,7 +841,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
}
max_headroom = LL_RESERVED_SPACE(rt->dst.dev) + sizeof(struct iphdr)
- + rt->dst.header_len + ip_encap_hlen(&tunnel->encap);
+ + rt->dst.header_len + encap_hlen;
if (skb_cow_head(skb, max_headroom)) {
ip_rt_put(rt);
@@ -845,6 +852,11 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
ip_tunnel_adj_headroom(dev, max_headroom);
+ if (ip_tunnel_encap(skb, &ipencap, &protocol, &fl4) < 0) {
+ ip_rt_put(rt);
+ goto tx_error;
+ }
+
iptunnel_xmit(NULL, rt, skb, fl4.saddr, fl4.daddr, protocol, tos, ttl,
df, !net_eq(tunnel->net, dev_net(dev)), 0);
return;
|
| 3/2 | 2026/09/06 05:01 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 4122 output: 51 thoughts: 291 Thoughts: **Analyzing the IP Tunnel Patch** Okay, so the changes are in `net/ipv4/ip_tunnel.c`. Let's dig in. It looks like the core modifications revolve around `ip_tunnel_xmit`, `tnl_update_pmtu`, and `ip_md_tunnel_xmit`. Right, the main thing is this new `encap_hlen` argument being introduced into `tnl_update_pmtu`. That makes sense; we need to account for the encapsulation header length when calculating the packet size for Path MTU discovery. In `tnl_update_pmtu`, the calculation is now `pkt_size = skb->len + encap_hlen - tunnel_hlen`. Makes perfect sense. Then, looking at `ip_tunnel_xmit`, I see they're grabbing `encap_hlen` from `tunnel->encap`. Smart to use `data_race` there, minimizes locking overhead. The error check `if (encap_hlen < 0) goto tx_error;` is crucial. They are also deferring `ip_tunnel_encap` until after `skb_cow_head` and `ip_tunnel_adj_headroom`. This should improve efficiency. Most importantly, `encap_hlen` is passed on to `tnl_update_pmtu`, and is also used in `max_headroom`. This is all logically connected, the header size is used in several places. I should probably take a look at the surrounding code in `net/ipv4/ip_tunnel.c` to see how this affects other functions and ensure there are no unintended consequences. And of course, double-check the Kconfig dependencies to make sure this doesn't introduce any build issues or unexpected configuration options. |
| 4/2 | 2026/09/06 05:01 | tool | grepper |
0mArgs:{
"Expression": "CONFIG_NET_IP_TUNNEL|obj-\\$\\(CONFIG_NET_IP_TUNNEL\\)|ip_tunnel",
"PathPrefix": "net/ipv4/"
}Results: {
"Output": "\nFull output is too long, showing 500 out of 1744 lines.\nUse more precise expression if possible.\n\nnet/ipv4/Makefile=6=obj-y := route.o inetpeer.o protocol.o \\\n--\nnet/ipv4/Makefile-15-\t fib_frontend.o fib_semantics.o fib_trie.o fib_notifier.o \\\nnet/ipv4/Makefile:16:\t inet_fragment.o ping.o ip_tunnel_core.o gre_offload.o \\\nnet/ipv4/Makefile-17-\t metrics.o netlink.o nexthop.o udp_tunnel_stub.o\nnet/ipv4/Makefile-18-\nnet/ipv4/Makefile:19:obj-$(CONFIG_NET_IP_TUNNEL) += ip_tunnel.o\nnet/ipv4/Makefile-20-obj-$(CONFIG_SYSCTL) += sysctl_net_ipv4.o\n--\nnet/ipv4/af_inet.c-112-#include \u003cnet/inet_common.h\u003e\nnet/ipv4/af_inet.c:113:#include \u003cnet/ip_tunnels.h\u003e\nnet/ipv4/af_inet.c-114-#include \u003cnet/xfrm.h\u003e\n--\nnet/ipv4/af_inet.c=1882=static int __init inet_init(void)\n--\nnet/ipv4/af_inet.c-2002-\nnet/ipv4/af_inet.c:2003:\tip_tunnel_core_init();\nnet/ipv4/af_inet.c-2004-\n--\nnet/ipv4/arp.c-112-#include \u003cnet/dst_metadata.h\u003e\nnet/ipv4/arp.c:113:#include \u003cnet/ip_tunnels.h\u003e\nnet/ipv4/arp.c-114-\n--\nnet/ipv4/fou_bpf.c=44=__bpf_kfunc int bpf_skb_set_fou_encap(struct __sk_buff *skb_ctx,\n--\nnet/ipv4/fou_bpf.c-47-\tstruct sk_buff *skb = (struct sk_buff *)skb_ctx;\nnet/ipv4/fou_bpf.c:48:\tstruct ip_tunnel_info *info = skb_tunnel_info(skb);\nnet/ipv4/fou_bpf.c-49-\n--\nnet/ipv4/fou_bpf.c=86=__bpf_kfunc int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx,\n--\nnet/ipv4/fou_bpf.c-89-\tstruct sk_buff *skb = (struct sk_buff *)skb_ctx;\nnet/ipv4/fou_bpf.c:90:\tstruct ip_tunnel_info *info = skb_tunnel_info(skb);\nnet/ipv4/fou_bpf.c-91-\n--\nnet/ipv4/fou_core.c=903=static struct genl_family fou_nl_family __ro_after_init = {\n--\nnet/ipv4/fou_core.c-915-\nnet/ipv4/fou_core.c:916:size_t fou_encap_hlen(struct ip_tunnel_encap *e)\nnet/ipv4/fou_core.c-917-{\n--\nnet/ipv4/fou_core.c=920=EXPORT_SYMBOL(fou_encap_hlen);\nnet/ipv4/fou_core.c-921-\nnet/ipv4/fou_core.c:922:size_t gue_encap_hlen(struct ip_tunnel_encap *e)\nnet/ipv4/fou_core.c-923-{\n--\nnet/ipv4/fou_core.c=938=EXPORT_SYMBOL(gue_encap_hlen);\nnet/ipv4/fou_core.c-939-\nnet/ipv4/fou_core.c:940:int __fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-941-\t\t u8 *protocol, __be16 *sport, int type)\n--\nnet/ipv4/fou_core.c=954=EXPORT_SYMBOL(__fou_build_header);\nnet/ipv4/fou_core.c-955-\nnet/ipv4/fou_core.c:956:int __gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-957-\t\t u8 *protocol, __be16 *sport, int type)\n--\nnet/ipv4/fou_core.c=1027=EXPORT_SYMBOL(__gue_build_header);\n--\nnet/ipv4/fou_core.c-1030-\nnet/ipv4/fou_core.c:1031:static void fou_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-1032-\t\t\t struct flowi4 *fl4, u8 *protocol, __be16 sport)\n--\nnet/ipv4/fou_core.c-1049-\nnet/ipv4/fou_core.c:1050:static int fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-1051-\t\t\t u8 *protocol, struct flowi4 *fl4)\n--\nnet/ipv4/fou_core.c-1066-\nnet/ipv4/fou_core.c:1067:static int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-1068-\t\t\t u8 *protocol, struct flowi4 *fl4)\n--\nnet/ipv4/fou_core.c=1096=static int gue_err(struct sk_buff *skb, u32 info)\n--\nnet/ipv4/fou_core.c-1161-\nnet/ipv4/fou_core.c:1162:static const struct ip_tunnel_encap_ops fou_iptun_ops = {\nnet/ipv4/fou_core.c-1163-\t.encap_hlen = fou_encap_hlen,\n--\nnet/ipv4/fou_core.c-1167-\nnet/ipv4/fou_core.c:1168:static const struct ip_tunnel_encap_ops gue_iptun_ops = {\nnet/ipv4/fou_core.c-1169-\t.encap_hlen = gue_encap_hlen,\n--\nnet/ipv4/fou_core.c-1173-\nnet/ipv4/fou_core.c:1174:static int ip_tunnel_encap_add_fou_ops(void)\nnet/ipv4/fou_core.c-1175-{\n--\nnet/ipv4/fou_core.c-1177-\nnet/ipv4/fou_core.c:1178:\tret = ip_tunnel_encap_add_ops(\u0026fou_iptun_ops, TUNNEL_ENCAP_FOU);\nnet/ipv4/fou_core.c-1179-\tif (ret \u003c 0) {\n--\nnet/ipv4/fou_core.c-1183-\nnet/ipv4/fou_core.c:1184:\tret = ip_tunnel_encap_add_ops(\u0026gue_iptun_ops, TUNNEL_ENCAP_GUE);\nnet/ipv4/fou_core.c-1185-\tif (ret \u003c 0) {\nnet/ipv4/fou_core.c-1186-\t\tpr_err(\"can't add gue ops\\n\");\nnet/ipv4/fou_core.c:1187:\t\tip_tunnel_encap_del_ops(\u0026fou_iptun_ops, TUNNEL_ENCAP_FOU);\nnet/ipv4/fou_core.c-1188-\t\treturn ret;\n--\nnet/ipv4/fou_core.c-1193-\nnet/ipv4/fou_core.c:1194:static void ip_tunnel_encap_del_fou_ops(void)\nnet/ipv4/fou_core.c-1195-{\nnet/ipv4/fou_core.c:1196:\tip_tunnel_encap_del_ops(\u0026fou_iptun_ops, TUNNEL_ENCAP_FOU);\nnet/ipv4/fou_core.c:1197:\tip_tunnel_encap_del_ops(\u0026gue_iptun_ops, TUNNEL_ENCAP_GUE);\nnet/ipv4/fou_core.c-1198-}\n--\nnet/ipv4/fou_core.c-1201-\nnet/ipv4/fou_core.c:1202:static int ip_tunnel_encap_add_fou_ops(void)\nnet/ipv4/fou_core.c-1203-{\n--\nnet/ipv4/fou_core.c-1206-\nnet/ipv4/fou_core.c:1207:static void ip_tunnel_encap_del_fou_ops(void)\nnet/ipv4/fou_core.c-1208-{\n--\nnet/ipv4/fou_core.c=1241=static int __init fou_init(void)\n--\nnet/ipv4/fou_core.c-1256-\nnet/ipv4/fou_core.c:1257:\tret = ip_tunnel_encap_add_fou_ops();\nnet/ipv4/fou_core.c-1258-\tif (ret == 0)\n--\nnet/ipv4/fou_core.c=1269=static void __exit fou_fini(void)\nnet/ipv4/fou_core.c-1270-{\nnet/ipv4/fou_core.c:1271:\tip_tunnel_encap_del_fou_ops();\nnet/ipv4/fou_core.c-1272-\tgenl_unregister_family(\u0026fou_nl_family);\n--\nnet/ipv4/ip_gre.c-35-#include \u003cnet/protocol.h\u003e\nnet/ipv4/ip_gre.c:36:#include \u003cnet/ip_tunnels.h\u003e\nnet/ipv4/ip_gre.c-37-#include \u003cnet/arp.h\u003e\n--\nnet/ipv4/ip_gre.c=122=static int ipgre_err(struct sk_buff *skb, u32 info,\n--\nnet/ipv4/ip_gre.c-139-\tstruct net *net = dev_net(skb-\u003edev);\nnet/ipv4/ip_gre.c:140:\tstruct ip_tunnel_net *itn;\nnet/ipv4/ip_gre.c-141-\tconst struct iphdr *iph;\n--\nnet/ipv4/ip_gre.c-143-\tconst int code = icmp_hdr(skb)-\u003ecode;\nnet/ipv4/ip_gre.c:144:\tstruct ip_tunnel *t;\nnet/ipv4/ip_gre.c-145-\n--\nnet/ipv4/ip_gre.c-154-\tiph = (const struct iphdr *)(icmp_hdr(skb) + 1);\nnet/ipv4/ip_gre.c:155:\tt = ip_tunnel_lookup(itn, skb-\u003edev-\u003eifindex, tpi-\u003eflags,\nnet/ipv4/ip_gre.c-156-\t\t\t iph-\u003edaddr, iph-\u003esaddr, tpi-\u003ekey);\n--\nnet/ipv4/ip_gre.c=267=static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi,\n--\nnet/ipv4/ip_gre.c-273-\tIP_TUNNEL_DECLARE_FLAGS(flags);\nnet/ipv4/ip_gre.c:274:\tstruct ip_tunnel_net *itn;\nnet/ipv4/ip_gre.c:275:\tstruct ip_tunnel *tunnel;\nnet/ipv4/ip_gre.c-276-\tconst struct iphdr *iph;\n--\nnet/ipv4/ip_gre.c-280-\nnet/ipv4/ip_gre.c:281:\tip_tunnel_flags_copy(flags, tpi-\u003eflags);\nnet/ipv4/ip_gre.c-282-\n--\nnet/ipv4/ip_gre.c-287-\t\t__set_bit(IP_TUNNEL_NO_KEY_BIT, flags);\nnet/ipv4/ip_gre.c:288:\t\ttunnel = ip_tunnel_lookup(itn, skb-\u003edev-\u003eifindex, flags,\nnet/ipv4/ip_gre.c-289-\t\t\t\t\t iph-\u003esaddr, iph-\u003edaddr, 0);\n--\nnet/ipv4/ip_gre.c-298-\t\t__set_bit(IP_TUNNEL_KEY_BIT, flags);\nnet/ipv4/ip_gre.c:299:\t\ttunnel = ip_tunnel_lookup(itn, skb-\u003edev-\u003eifindex, flags,\nnet/ipv4/ip_gre.c-300-\t\t\t\t\t iph-\u003esaddr, iph-\u003edaddr, tpi-\u003ekey);\n--\nnet/ipv4/ip_gre.c-319-\t\t\tstruct erspan_metadata *pkt_md, *md;\nnet/ipv4/ip_gre.c:320:\t\t\tstruct ip_tunnel_info *info;\nnet/ipv4/ip_gre.c-321-\t\t\tunsigned char *gh;\n--\nnet/ipv4/ip_gre.c-324-\t\t\t__set_bit(IP_TUNNEL_KEY_BIT, tpi-\u003eflags);\nnet/ipv4/ip_gre.c:325:\t\t\tip_tunnel_flags_copy(flags, tpi-\u003eflags);\nnet/ipv4/ip_gre.c-326-\t\t\ttun_id = key32_to_tunnel_id(tpi-\u003ekey);\n--\nnet/ipv4/ip_gre.c-344-\t\t\t\t\t\t\t sizeof(*ershdr));\nnet/ipv4/ip_gre.c:345:\t\t\tmd = ip_tunnel_info_opts(\u0026tun_dst-\u003eu.tun_info);\nnet/ipv4/ip_gre.c-346-\t\t\tmd-\u003eversion = ver;\n--\nnet/ipv4/ip_gre.c-355-\t\tskb_reset_mac_header(skb);\nnet/ipv4/ip_gre.c:356:\t\tip_tunnel_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);\nnet/ipv4/ip_gre.c-357-\t\treturn PACKET_RCVD;\n--\nnet/ipv4/ip_gre.c=366=static int __ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,\nnet/ipv4/ip_gre.c:367:\t\t struct ip_tunnel_net *itn, int hdr_len, bool raw_proto)\nnet/ipv4/ip_gre.c-368-{\n--\nnet/ipv4/ip_gre.c-370-\tconst struct iphdr *iph;\nnet/ipv4/ip_gre.c:371:\tstruct ip_tunnel *tunnel;\nnet/ipv4/ip_gre.c-372-\nnet/ipv4/ip_gre.c-373-\tiph = ip_hdr(skb);\nnet/ipv4/ip_gre.c:374:\ttunnel = ip_tunnel_lookup(itn, skb-\u003edev-\u003eifindex, tpi-\u003eflags,\nnet/ipv4/ip_gre.c-375-\t\t\t\t iph-\u003esaddr, iph-\u003edaddr, tpi-\u003ekey);\n--\nnet/ipv4/ip_gre.c-398-\t\t\t__set_bit(IP_TUNNEL_KEY_BIT, flags);\nnet/ipv4/ip_gre.c:399:\t\t\tip_tunnel_flags_and(flags, tpi-\u003eflags, flags);\nnet/ipv4/ip_gre.c-400-\n--\nnet/ipv4/ip_gre.c-406-\nnet/ipv4/ip_gre.c:407:\t\tip_tunnel_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);\nnet/ipv4/ip_gre.c-408-\t\treturn PACKET_RCVD;\n--\nnet/ipv4/ip_gre.c=417=static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,\n--\nnet/ipv4/ip_gre.c-420-\tstruct net *net = dev_net(skb-\u003edev);\nnet/ipv4/ip_gre.c:421:\tstruct ip_tunnel_net *itn;\nnet/ipv4/ip_gre.c-422-\tint res;\n--\nnet/ipv4/ip_gre.c=476=static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,\n--\nnet/ipv4/ip_gre.c-479-{\nnet/ipv4/ip_gre.c:480:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-481-\tIP_TUNNEL_DECLARE_FLAGS(flags);\nnet/ipv4/ip_gre.c-482-\nnet/ipv4/ip_gre.c:483:\tip_tunnel_flags_copy(flags, tunnel-\u003eparms.o_flags);\nnet/ipv4/ip_gre.c-484-\n--\nnet/ipv4/ip_gre.c-490-\nnet/ipv4/ip_gre.c:491:\tip_tunnel_xmit(skb, dev, tnl_params, tnl_params-\u003eprotocol);\nnet/ipv4/ip_gre.c-492-}\n--\nnet/ipv4/ip_gre.c=499=static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev,\n--\nnet/ipv4/ip_gre.c-501-{\nnet/ipv4/ip_gre.c:502:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-503-\tIP_TUNNEL_DECLARE_FLAGS(flags) = { };\nnet/ipv4/ip_gre.c:504:\tstruct ip_tunnel_info *tun_info;\nnet/ipv4/ip_gre.c:505:\tconst struct ip_tunnel_key *key;\nnet/ipv4/ip_gre.c-506-\tint tunnel_hlen;\n--\nnet/ipv4/ip_gre.c-509-\tif (unlikely(!tun_info || !(tun_info-\u003emode \u0026 IP_TUNNEL_INFO_TX) ||\nnet/ipv4/ip_gre.c:510:\t\t ip_tunnel_info_af(tun_info) != AF_INET))\nnet/ipv4/ip_gre.c-511-\t\tgoto err_free_skb;\n--\nnet/ipv4/ip_gre.c-526-\t__set_bit(IP_TUNNEL_SEQ_BIT, flags);\nnet/ipv4/ip_gre.c:527:\tip_tunnel_flags_and(flags, tun_info-\u003ekey.tun_flags, flags);\nnet/ipv4/ip_gre.c-528-\n--\nnet/ipv4/ip_gre.c=543=static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev)\nnet/ipv4/ip_gre.c-544-{\nnet/ipv4/ip_gre.c:545:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-546-\tIP_TUNNEL_DECLARE_FLAGS(flags) = { };\nnet/ipv4/ip_gre.c:547:\tstruct ip_tunnel_info *tun_info;\nnet/ipv4/ip_gre.c:548:\tconst struct ip_tunnel_key *key;\nnet/ipv4/ip_gre.c-549-\tstruct erspan_metadata *md;\n--\nnet/ipv4/ip_gre.c-557-\tif (unlikely(!tun_info || !(tun_info-\u003emode \u0026 IP_TUNNEL_INFO_TX) ||\nnet/ipv4/ip_gre.c:558:\t\t ip_tunnel_info_af(tun_info) != AF_INET))\nnet/ipv4/ip_gre.c-559-\t\tgoto err_free_skb;\n--\nnet/ipv4/ip_gre.c-565-\t\tgoto err_free_skb;\nnet/ipv4/ip_gre.c:566:\tmd = ip_tunnel_info_opts(tun_info);\nnet/ipv4/ip_gre.c-567-\n--\nnet/ipv4/ip_gre.c=628=static int gre_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)\nnet/ipv4/ip_gre.c-629-{\nnet/ipv4/ip_gre.c:630:\tstruct ip_tunnel_info *info = skb_tunnel_info(skb);\nnet/ipv4/ip_gre.c:631:\tconst struct ip_tunnel_key *key;\nnet/ipv4/ip_gre.c-632-\tstruct rtable *rt;\n--\nnet/ipv4/ip_gre.c-634-\nnet/ipv4/ip_gre.c:635:\tif (ip_tunnel_info_af(info) != AF_INET)\nnet/ipv4/ip_gre.c-636-\t\treturn -EINVAL;\n--\nnet/ipv4/ip_gre.c-638-\tkey = \u0026info-\u003ekey;\nnet/ipv4/ip_gre.c:639:\tip_tunnel_init_flow(\u0026fl4, IPPROTO_GRE, key-\u003eu.ipv4.dst, key-\u003eu.ipv4.src,\nnet/ipv4/ip_gre.c-640-\t\t\t tunnel_id_to_key32(key-\u003etun_id),\n--\nnet/ipv4/ip_gre.c=652=static netdev_tx_t ipgre_xmit(struct sk_buff *skb,\n--\nnet/ipv4/ip_gre.c-654-{\nnet/ipv4/ip_gre.c:655:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-656-\tconst struct iphdr *tnl_params;\n--\nnet/ipv4/ip_gre.c-676-\nnet/ipv4/ip_gre.c:677:\t\t/* ip_tunnel_xmit() needs skb-\u003edata pointing to gre header. */\nnet/ipv4/ip_gre.c-678-\t\tskb_pull(skb, pull_len);\n--\nnet/ipv4/ip_gre.c=704=static netdev_tx_t erspan_xmit(struct sk_buff *skb,\n--\nnet/ipv4/ip_gre.c-706-{\nnet/ipv4/ip_gre.c:707:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-708-\tbool truncate = false;\n--\nnet/ipv4/ip_gre.c=759=static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,\n--\nnet/ipv4/ip_gre.c-761-{\nnet/ipv4/ip_gre.c:762:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-763-\n--\nnet/ipv4/ip_gre.c=788=static void ipgre_link_update(struct net_device *dev, bool set_mtu)\nnet/ipv4/ip_gre.c-789-{\nnet/ipv4/ip_gre.c:790:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-791-\tint len;\n--\nnet/ipv4/ip_gre.c=817=static int ipgre_tunnel_ctl(struct net_device *dev,\nnet/ipv4/ip_gre.c:818:\t\t\t struct ip_tunnel_parm_kern *p,\nnet/ipv4/ip_gre.c-819-\t\t\t int cmd)\n--\nnet/ipv4/ip_gre.c-823-\nnet/ipv4/ip_gre.c:824:\tif (!ip_tunnel_flags_is_be16_compat(p-\u003ei_flags) ||\nnet/ipv4/ip_gre.c:825:\t !ip_tunnel_flags_is_be16_compat(p-\u003eo_flags))\nnet/ipv4/ip_gre.c-826-\t\treturn -EOVERFLOW;\nnet/ipv4/ip_gre.c-827-\nnet/ipv4/ip_gre.c:828:\ti_flags = ip_tunnel_flags_to_be16(p-\u003ei_flags);\nnet/ipv4/ip_gre.c:829:\to_flags = ip_tunnel_flags_to_be16(p-\u003eo_flags);\nnet/ipv4/ip_gre.c-830-\n--\nnet/ipv4/ip_gre.c-840-\nnet/ipv4/ip_gre.c:841:\terr = ip_tunnel_ctl(dev, p, cmd);\nnet/ipv4/ip_gre.c-842-\tif (err)\n--\nnet/ipv4/ip_gre.c-845-\tif (cmd == SIOCCHGTUNNEL) {\nnet/ipv4/ip_gre.c:846:\t\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c-847-\nnet/ipv4/ip_gre.c:848:\t\tip_tunnel_flags_copy(t-\u003eparms.i_flags, p-\u003ei_flags);\nnet/ipv4/ip_gre.c:849:\t\tip_tunnel_flags_copy(t-\u003eparms.o_flags, p-\u003eo_flags);\nnet/ipv4/ip_gre.c-850-\n--\nnet/ipv4/ip_gre.c-855-\ti_flags = gre_tnl_flags_to_gre_flags(p-\u003ei_flags);\nnet/ipv4/ip_gre.c:856:\tip_tunnel_flags_from_be16(p-\u003ei_flags, i_flags);\nnet/ipv4/ip_gre.c-857-\to_flags = gre_tnl_flags_to_gre_flags(p-\u003eo_flags);\nnet/ipv4/ip_gre.c:858:\tip_tunnel_flags_from_be16(p-\u003eo_flags, o_flags);\nnet/ipv4/ip_gre.c-859-\n--\nnet/ipv4/ip_gre.c=890=static int ipgre_header(struct sk_buff *skb, struct net_device *dev,\n--\nnet/ipv4/ip_gre.c-893-{\nnet/ipv4/ip_gre.c:894:\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c-895-\tstruct gre_base_hdr *greh;\n--\nnet/ipv4/ip_gre.c=937=static int ipgre_open(struct net_device *dev)\nnet/ipv4/ip_gre.c-938-{\nnet/ipv4/ip_gre.c:939:\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c-940-\n--\nnet/ipv4/ip_gre.c=966=static int ipgre_close(struct net_device *dev)\nnet/ipv4/ip_gre.c-967-{\nnet/ipv4/ip_gre.c:968:\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c-969-\n--\nnet/ipv4/ip_gre.c=980=static const struct net_device_ops ipgre_netdev_ops = {\nnet/ipv4/ip_gre.c-981-\t.ndo_init\t\t= ipgre_tunnel_init,\nnet/ipv4/ip_gre.c:982:\t.ndo_uninit\t\t= ip_tunnel_uninit,\nnet/ipv4/ip_gre.c-983-#ifdef CONFIG_NET_IPGRE_BROADCAST\n--\nnet/ipv4/ip_gre.c-987-\t.ndo_start_xmit\t\t= ipgre_xmit,\nnet/ipv4/ip_gre.c:988:\t.ndo_siocdevprivate\t= ip_tunnel_siocdevprivate,\nnet/ipv4/ip_gre.c:989:\t.ndo_change_mtu\t\t= ip_tunnel_change_mtu,\nnet/ipv4/ip_gre.c-990-\t.ndo_get_stats64\t= dev_get_tstats64,\nnet/ipv4/ip_gre.c:991:\t.ndo_get_iflink\t\t= ip_tunnel_get_iflink,\nnet/ipv4/ip_gre.c-992-\t.ndo_tunnel_ctl\t\t= ipgre_tunnel_ctl,\n--\nnet/ipv4/ip_gre.c=1000=static void ipgre_tunnel_setup(struct net_device *dev)\n--\nnet/ipv4/ip_gre.c-1003-\tdev-\u003etype\t\t= ARPHRD_IPGRE;\nnet/ipv4/ip_gre.c:1004:\tip_tunnel_setup(dev, ipgre_net_id);\nnet/ipv4/ip_gre.c-1005-}\n--\nnet/ipv4/ip_gre.c=1007=static void __gre_tunnel_init(struct net_device *dev)\nnet/ipv4/ip_gre.c-1008-{\nnet/ipv4/ip_gre.c:1009:\tstruct ip_tunnel *tunnel;\nnet/ipv4/ip_gre.c-1010-\n--\nnet/ipv4/ip_gre.c=1036=static int ipgre_tunnel_init(struct net_device *dev)\nnet/ipv4/ip_gre.c-1037-{\nnet/ipv4/ip_gre.c:1038:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-1039-\tstruct iphdr *iph = \u0026tunnel-\u003eparms.iph;\n--\nnet/ipv4/ip_gre.c-1066-\nnet/ipv4/ip_gre.c:1067:\treturn ip_tunnel_init(dev);\nnet/ipv4/ip_gre.c-1068-}\n--\nnet/ipv4/ip_gre.c=1075=static int __net_init ipgre_init_net(struct net *net)\nnet/ipv4/ip_gre.c-1076-{\nnet/ipv4/ip_gre.c:1077:\treturn ip_tunnel_init_net(net, ipgre_net_id, \u0026ipgre_link_ops, NULL);\nnet/ipv4/ip_gre.c-1078-}\n--\nnet/ipv4/ip_gre.c=1080=static void __net_exit ipgre_exit_rtnl(struct net *net,\n--\nnet/ipv4/ip_gre.c-1082-{\nnet/ipv4/ip_gre.c:1083:\tip_tunnel_delete_net(net, ipgre_net_id, \u0026ipgre_link_ops, dev_to_kill);\nnet/ipv4/ip_gre.c-1084-}\n--\nnet/ipv4/ip_gre.c=1086=static struct pernet_operations ipgre_net_ops = {\n--\nnet/ipv4/ip_gre.c-1089-\t.id = \u0026ipgre_net_id,\nnet/ipv4/ip_gre.c:1090:\t.size = sizeof(struct ip_tunnel_net),\nnet/ipv4/ip_gre.c-1091-};\n--\nnet/ipv4/ip_gre.c=1182=static int ipgre_netlink_parms(struct net_device *dev,\n--\nnet/ipv4/ip_gre.c-1184-\t\t\t\tstruct nlattr *tb[],\nnet/ipv4/ip_gre.c:1185:\t\t\t\tstruct ip_tunnel_parm_kern *parms,\nnet/ipv4/ip_gre.c-1186-\t\t\t\t__u32 *fwmark)\nnet/ipv4/ip_gre.c-1187-{\nnet/ipv4/ip_gre.c:1188:\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c-1189-\n--\nnet/ipv4/ip_gre.c=1251=static int erspan_netlink_parms(struct net_device *dev,\n--\nnet/ipv4/ip_gre.c-1253-\t\t\t\tstruct nlattr *tb[],\nnet/ipv4/ip_gre.c:1254:\t\t\t\tstruct ip_tunnel_parm_kern *parms,\nnet/ipv4/ip_gre.c-1255-\t\t\t\t__u32 *fwmark)\nnet/ipv4/ip_gre.c-1256-{\nnet/ipv4/ip_gre.c:1257:\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c-1258-\tint err;\n--\nnet/ipv4/ip_gre.c=1296=static bool ipgre_netlink_encap_parms(struct nlattr *data[],\nnet/ipv4/ip_gre.c:1297:\t\t\t\t struct ip_tunnel_encap *ipencap)\nnet/ipv4/ip_gre.c-1298-{\n--\nnet/ipv4/ip_gre.c=1329=static int gre_tap_init(struct net_device *dev)\n--\nnet/ipv4/ip_gre.c-1334-\nnet/ipv4/ip_gre.c:1335:\treturn ip_tunnel_init(dev);\nnet/ipv4/ip_gre.c-1336-}\n--\nnet/ipv4/ip_gre.c=1338=static const struct net_device_ops gre_tap_netdev_ops = {\nnet/ipv4/ip_gre.c-1339-\t.ndo_init\t\t= gre_tap_init,\nnet/ipv4/ip_gre.c:1340:\t.ndo_uninit\t\t= ip_tunnel_uninit,\nnet/ipv4/ip_gre.c-1341-\t.ndo_start_xmit\t\t= gre_tap_xmit,\n--\nnet/ipv4/ip_gre.c-1343-\t.ndo_validate_addr\t= eth_validate_addr,\nnet/ipv4/ip_gre.c:1344:\t.ndo_change_mtu\t\t= ip_tunnel_change_mtu,\nnet/ipv4/ip_gre.c-1345-\t.ndo_get_stats64\t= dev_get_tstats64,\nnet/ipv4/ip_gre.c:1346:\t.ndo_get_iflink\t\t= ip_tunnel_get_iflink,\nnet/ipv4/ip_gre.c-1347-\t.ndo_fill_metadata_dst\t= gre_fill_metadata_dst,\n--\nnet/ipv4/ip_gre.c=1350=static int erspan_tunnel_init(struct net_device *dev)\nnet/ipv4/ip_gre.c-1351-{\nnet/ipv4/ip_gre.c:1352:\tstruct ip_tunnel *tunnel = netdev_priv(dev);\nnet/ipv4/ip_gre.c-1353-\n--\nnet/ipv4/ip_gre.c-1367-\nnet/ipv4/ip_gre.c:1368:\treturn ip_tunnel_init(dev);\nnet/ipv4/ip_gre.c-1369-}\n--\nnet/ipv4/ip_gre.c=1371=static const struct net_device_ops erspan_netdev_ops = {\nnet/ipv4/ip_gre.c-1372-\t.ndo_init\t\t= erspan_tunnel_init,\nnet/ipv4/ip_gre.c:1373:\t.ndo_uninit\t\t= ip_tunnel_uninit,\nnet/ipv4/ip_gre.c-1374-\t.ndo_start_xmit\t\t= erspan_xmit,\n--\nnet/ipv4/ip_gre.c-1376-\t.ndo_validate_addr\t= eth_validate_addr,\nnet/ipv4/ip_gre.c:1377:\t.ndo_change_mtu\t\t= ip_tunnel_change_mtu,\nnet/ipv4/ip_gre.c-1378-\t.ndo_get_stats64\t= dev_get_tstats64,\nnet/ipv4/ip_gre.c:1379:\t.ndo_get_iflink\t\t= ip_tunnel_get_iflink,\nnet/ipv4/ip_gre.c-1380-\t.ndo_fill_metadata_dst\t= gre_fill_metadata_dst,\n--\nnet/ipv4/ip_gre.c=1383=static void ipgre_tap_setup(struct net_device *dev)\n--\nnet/ipv4/ip_gre.c-1389-\tdev-\u003epriv_flags\t|= IFF_LIVE_ADDR_CHANGE;\nnet/ipv4/ip_gre.c:1390:\tip_tunnel_setup(dev, gre_tap_net_id);\nnet/ipv4/ip_gre.c-1391-}\n--\nnet/ipv4/ip_gre.c=1394=ipgre_newlink_encap_setup(struct net_device *dev, struct nlattr *data[])\nnet/ipv4/ip_gre.c-1395-{\nnet/ipv4/ip_gre.c:1396:\tstruct ip_tunnel_encap ipencap;\nnet/ipv4/ip_gre.c-1397-\nnet/ipv4/ip_gre.c-1398-\tif (ipgre_netlink_encap_parms(data, \u0026ipencap)) {\nnet/ipv4/ip_gre.c:1399:\t\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c:1400:\t\tint err = ip_tunnel_encap_setup(t, \u0026ipencap);\nnet/ipv4/ip_gre.c-1401-\n--\nnet/ipv4/ip_gre.c=1409=static int ipgre_newlink(struct net_device *dev,\n--\nnet/ipv4/ip_gre.c-1414-\tstruct nlattr **tb = params-\u003etb;\nnet/ipv4/ip_gre.c:1415:\tstruct ip_tunnel_parm_kern p;\nnet/ipv4/ip_gre.c-1416-\t__u32 fwmark = 0;\n--\nnet/ipv4/ip_gre.c-1425-\t\treturn err;\nnet/ipv4/ip_gre.c:1426:\treturn ip_tunnel_newlink(params-\u003elink_net ? : dev_net(dev), dev, tb, \u0026p,\nnet/ipv4/ip_gre.c-1427-\t\t\t\t fwmark);\n--\nnet/ipv4/ip_gre.c=1430=static int erspan_newlink(struct net_device *dev,\n--\nnet/ipv4/ip_gre.c-1435-\tstruct nlattr **tb = params-\u003etb;\nnet/ipv4/ip_gre.c:1436:\tstruct ip_tunnel_parm_kern p;\nnet/ipv4/ip_gre.c-1437-\t__u32 fwmark = 0;\n--\nnet/ipv4/ip_gre.c-1446-\t\treturn err;\nnet/ipv4/ip_gre.c:1447:\treturn ip_tunnel_newlink(params-\u003elink_net ? : dev_net(dev), dev, tb, \u0026p,\nnet/ipv4/ip_gre.c-1448-\t\t\t\t fwmark);\n--\nnet/ipv4/ip_gre.c=1451=static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],\n--\nnet/ipv4/ip_gre.c-1454-{\nnet/ipv4/ip_gre.c:1455:\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c:1456:\tstruct ip_tunnel_parm_kern p;\nnet/ipv4/ip_gre.c-1457-\t__u32 fwmark = t-\u003efwmark;\n--\nnet/ipv4/ip_gre.c-1467-\nnet/ipv4/ip_gre.c:1468:\terr = ip_tunnel_changelink(dev, tb, \u0026p, fwmark);\nnet/ipv4/ip_gre.c-1469-\tif (err \u003c 0)\n--\nnet/ipv4/ip_gre.c-1471-\nnet/ipv4/ip_gre.c:1472:\tip_tunnel_flags_copy(t-\u003eparms.i_flags, p.i_flags);\nnet/ipv4/ip_gre.c:1473:\tip_tunnel_flags_copy(t-\u003eparms.o_flags, p.o_flags);\nnet/ipv4/ip_gre.c-1474-\n--\nnet/ipv4/ip_gre.c=1480=static int erspan_changelink(struct net_device *dev, struct nlattr *tb[],\n--\nnet/ipv4/ip_gre.c-1483-{\nnet/ipv4/ip_gre.c:1484:\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c:1485:\tstruct ip_tunnel_parm_kern p;\nnet/ipv4/ip_gre.c-1486-\t__u32 fwmark = t-\u003efwmark;\n--\nnet/ipv4/ip_gre.c-1496-\nnet/ipv4/ip_gre.c:1497:\terr = ip_tunnel_changelink(dev, tb, \u0026p, fwmark);\n\n"
} |
| 5/2 | 2026/09/06 05:01 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 15871 output: 48 thoughts: 26 Thoughts: Here's my take on those thoughts: **Investigating the IP Tunnel Configuration** Okay, so I need to figure out what's enabling `ip_tunnel.c`. My instinct is to dive into the Kconfig files, specifically `net/ipv4/Kconfig`. That's usually where the core network configuration options live for IPv4. I'm assuming that's where the relevant symbols and dependencies for IP tunneling are defined. I need to trace back from that file and understand the conditional compilation. Let's see what I can find... I expect to see some options related to tunneling, GRE, IPIP, or similar technologies. The goal is to identify the config symbol that needs to be set to build and enable the tunnel functionality. |
| 6/2 | 2026/09/06 05:01 | tool | grepper |
0mArgs:{
"Expression": "NET_IP_TUNNEL|NET_IPGRE|NET_IPIP|NET_FOU",
"PathPrefix": "net/ipv4/Kconfig"
}Results: {
"Output": "net/ipv4/Kconfig=149=config IP_PNP_RARP\n--\nnet/ipv4/Kconfig-161-\nnet/ipv4/Kconfig:162:config NET_IPIP\nnet/ipv4/Kconfig-163-\ttristate \"IP: tunneling\"\nnet/ipv4/Kconfig-164-\tselect INET_TUNNEL\nnet/ipv4/Kconfig:165:\tselect NET_IP_TUNNEL\nnet/ipv4/Kconfig-166-\thelp\n--\nnet/ipv4/Kconfig-179-\nnet/ipv4/Kconfig:180:config NET_IPGRE_DEMUX\nnet/ipv4/Kconfig-181-\ttristate \"IP: GRE demultiplexer\"\n--\nnet/ipv4/Kconfig-185-\nnet/ipv4/Kconfig:186:config NET_IP_TUNNEL\nnet/ipv4/Kconfig-187-\ttristate\n--\nnet/ipv4/Kconfig-191-\nnet/ipv4/Kconfig:192:config NET_IPGRE\nnet/ipv4/Kconfig-193-\ttristate \"IP: GRE tunnels over IP\"\nnet/ipv4/Kconfig:194:\tdepends on NET_IPGRE_DEMUX\nnet/ipv4/Kconfig:195:\tselect NET_IP_TUNNEL\nnet/ipv4/Kconfig-196-\thelp\n--\nnet/ipv4/Kconfig-206-\nnet/ipv4/Kconfig:207:config NET_IPGRE_BROADCAST\nnet/ipv4/Kconfig-208-\tbool \"IP: broadcast GRE over IP\"\nnet/ipv4/Kconfig:209:\tdepends on IP_MULTICAST \u0026\u0026 NET_IPGRE\nnet/ipv4/Kconfig-210-\thelp\n--\nnet/ipv4/Kconfig=304=config NET_IPVTI\n--\nnet/ipv4/Kconfig-306-\tselect INET_TUNNEL\nnet/ipv4/Kconfig:307:\tselect NET_IP_TUNNEL\nnet/ipv4/Kconfig-308-\tselect XFRM\n--\nnet/ipv4/Kconfig=316=config NET_UDP_TUNNEL\nnet/ipv4/Kconfig-317-\ttristate\nnet/ipv4/Kconfig:318:\tselect NET_IP_TUNNEL\nnet/ipv4/Kconfig-319-\tdefault n\nnet/ipv4/Kconfig-320-\nnet/ipv4/Kconfig:321:config NET_FOU\nnet/ipv4/Kconfig-322-\ttristate \"IP: Foo (IP protocols) over UDP\"\n--\nnet/ipv4/Kconfig-329-\nnet/ipv4/Kconfig:330:config NET_FOU_IP_TUNNELS\nnet/ipv4/Kconfig-331-\tbool \"IP: FOU encapsulation of IP tunnels\"\nnet/ipv4/Kconfig:332:\tdepends on NET_IPIP || NET_IPGRE || IPV6_SIT\nnet/ipv4/Kconfig:333:\tselect NET_FOU\nnet/ipv4/Kconfig-334-\thelp\n"
} |
| 7/2 | 2026/09/06 05:01 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 16924 output: 38 thoughts: 32 Thoughts: Here's a summary of my mental process: **Diving into the IPv4 Tunnel Code** Okay, time to dig into the heart of the IPv4 tunneling implementation. I need to get a better handle on how this works, so I'm going to start by loading up `net/ipv4/ip_tunnel.c`. I'm going to use `read-file` to get a good look at the relevant code. Based on the surrounding code I remember, I think the section between lines 500 and 860 is where I'll find the core logic for... well, probably the encapsulation/decapsulation process, or maybe the handling of tunnel device creation and deletion. That range feels about right for the meat of the tunneling functionality, the bit I want to understand better. I need to know how the tunnel protocol actually manipulates the IP packets. Let's see what we can find. I anticipate a good chunk of switch statements and helper function calls in there. Should be interesting. |
| 8/2 | 2026/09/06 05:01 | tool | read-file |
0mArgs:{
"File": "net/ipv4/ip_tunnel.c",
"FirstLine": 510,
"LineCount": 80
}Results: {
"Contents": " 510:\tEXPORT_SYMBOL_GPL(ip_tunnel_encap_setup);\n 511:\t\n 512:\tstatic int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,\n 513:\t\t\t\t struct rtable *rt, __be16 df,\n 514:\t\t\t\t const struct iphdr *inner_iph,\n 515:\t\t\t\t int tunnel_hlen, __be32 dst, bool md,\n 516:\t\t\t\t int encap_hlen)\n 517:\t{\n 518:\t\tstruct ip_tunnel *tunnel = netdev_priv(dev);\n 519:\t\tint pkt_size;\n 520:\t\tint mtu;\n 521:\t\n 522:\t\ttunnel_hlen = md ? tunnel_hlen : tunnel-\u003ehlen;\n 523:\t\tpkt_size = skb-\u003elen + encap_hlen - tunnel_hlen;\n 524:\t\tpkt_size -= dev-\u003etype == ARPHRD_ETHER ? dev-\u003ehard_header_len : 0;\n 525:\t\n 526:\t\tif (df) {\n 527:\t\t\tmtu = dst_mtu(\u0026rt-\u003edst) - (sizeof(struct iphdr) + tunnel_hlen);\n 528:\t\t\tmtu -= dev-\u003etype == ARPHRD_ETHER ? dev-\u003ehard_header_len : 0;\n 529:\t\t} else {\n 530:\t\t\tmtu = skb_valid_dst(skb) ? dst_mtu(skb_dst(skb)) : dev-\u003emtu;\n 531:\t\t}\n 532:\t\n 533:\t\tif (skb_valid_dst(skb))\n 534:\t\t\tskb_dst_update_pmtu_no_confirm(skb, mtu);\n 535:\t\n 536:\t\tif (skb-\u003eprotocol == htons(ETH_P_IP)) {\n 537:\t\t\tif (!skb_is_gso(skb) \u0026\u0026\n 538:\t\t\t (inner_iph-\u003efrag_off \u0026 htons(IP_DF)) \u0026\u0026\n 539:\t\t\t mtu \u003c pkt_size) {\n 540:\t\t\t\ticmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));\n 541:\t\t\t\treturn -E2BIG;\n 542:\t\t\t}\n 543:\t\t}\n 544:\t#if IS_ENABLED(CONFIG_IPV6)\n 545:\t\telse if (skb-\u003eprotocol == htons(ETH_P_IPV6)) {\n 546:\t\t\tstruct rt6_info *rt6;\n 547:\t\t\t__be32 daddr;\n 548:\t\n 549:\t\t\trt6 = skb_valid_dst(skb) ? dst_rt6_info(skb_dst(skb)) :\n 550:\t\t\t\t\t\t NULL;\n 551:\t\t\tdaddr = md ? dst : tunnel-\u003eparms.iph.daddr;\n 552:\t\n 553:\t\t\tif (rt6 \u0026\u0026 mtu \u003c dst_mtu(skb_dst(skb)) \u0026\u0026\n 554:\t\t\t\t mtu \u003e= IPV6_MIN_MTU) {\n 555:\t\t\t\tif ((daddr \u0026\u0026 !ipv4_is_multicast(daddr)) ||\n 556:\t\t\t\t rt6-\u003ert6i_dst.plen == 128) {\n 557:\t\t\t\t\trt6-\u003ert6i_flags |= RTF_MODIFIED;\n 558:\t\t\t\t\tdst_metric_set(skb_dst(skb), RTAX_MTU, mtu);\n 559:\t\t\t\t}\n 560:\t\t\t}\n 561:\t\n 562:\t\t\tif (!skb_is_gso(skb) \u0026\u0026 mtu \u003e= IPV6_MIN_MTU \u0026\u0026\n 563:\t\t\t\t\t\tmtu \u003c pkt_size) {\n 564:\t\t\t\ticmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);\n 565:\t\t\t\treturn -E2BIG;\n 566:\t\t\t}\n 567:\t\t}\n 568:\t#endif\n 569:\t\treturn 0;\n 570:\t}\n 571:\t\n 572:\tvoid ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n 573:\t\t\t u8 proto, int tunnel_hlen)\n 574:\t{\n 575:\t\tstruct ip_tunnel *tunnel = netdev_priv(dev);\n 576:\t\tu32 headroom = sizeof(struct iphdr);\n 577:\t\tstruct ip_tunnel_info *tun_info;\n 578:\t\tconst struct ip_tunnel_key *key;\n 579:\t\tconst struct iphdr *inner_iph;\n 580:\t\tstruct rtable *rt = NULL;\n 581:\t\tstruct flowi4 fl4;\n 582:\t\t__be16 df = 0;\n 583:\t\tu8 tos, ttl;\n 584:\t\tbool use_cache;\n 585:\t\n 586:\t\ttun_info = skb_tunnel_info(skb);\n 587:\t\tif (unlikely(!tun_info || !(tun_info-\u003emode \u0026 IP_TUNNEL_INFO_TX) ||\n 588:\t\t\t ip_tunnel_info_af(tun_info) != AF_INET))\n 589:\t\t\tgoto tx_error;\n"
} |
| 9/2 | 2026/09/06 05:01 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 18631 output: 39 thoughts: 18 Thoughts: Okay, let's dive into this. I'm going to carefully examine the remaining code within `ip_tunnel_xmit`. I need to fully grasp its operation. I'll need to understand the control flow, the data structures it manipulates, and the purpose of each section of the code to properly assess it. |
| 10/2 | 2026/09/06 05:01 | tool | read-file |
0mArgs:{
"File": "net/ipv4/ip_tunnel.c",
"FirstLine": 760,
"LineCount": 100
}Results: {
"Contents": " 760:\t\t\t} else if (payload_protocol == htons(ETH_P_IPV6)) {\n 761:\t\t\t\ttos = ipv6_get_dsfield((const struct ipv6hdr *)inner_iph);\n 762:\t\t\t\tconnected = false;\n 763:\t\t\t}\n 764:\t\t}\n 765:\t\n 766:\t\tip_tunnel_init_flow(\u0026fl4, protocol, dst, tnl_params-\u003esaddr,\n 767:\t\t\t\t tunnel-\u003eparms.o_key, tos \u0026 INET_DSCP_MASK,\n 768:\t\t\t\t tunnel-\u003enet, READ_ONCE(tunnel-\u003eparms.link),\n 769:\t\t\t\t tunnel-\u003efwmark, skb_get_hash(skb), 0);\n 770:\t\n 771:\t\t/* Snapshot encap; ipgre_changelink() can update it concurrently. */\n 772:\t\tipencap = data_race(tunnel-\u003eencap);\n 773:\t\tencap_hlen = ip_encap_hlen(\u0026ipencap);\n 774:\t\tif (encap_hlen \u003c 0)\n 775:\t\t\tgoto tx_error;\n 776:\t\n 777:\t\tif (connected \u0026\u0026 md) {\n 778:\t\t\tuse_cache = ip_tunnel_dst_cache_usable(skb, tun_info);\n 779:\t\t\tif (use_cache)\n 780:\t\t\t\trt = dst_cache_get_ip4(\u0026tun_info-\u003edst_cache,\n 781:\t\t\t\t\t\t \u0026fl4.saddr);\n 782:\t\t} else {\n 783:\t\t\trt = connected ? dst_cache_get_ip4(\u0026tunnel-\u003edst_cache,\n 784:\t\t\t\t\t\t\t\u0026fl4.saddr) : NULL;\n 785:\t\t}\n 786:\t\n 787:\t\tif (!rt) {\n 788:\t\t\trt = ip_route_output_key(tunnel-\u003enet, \u0026fl4);\n 789:\t\n 790:\t\t\tif (IS_ERR(rt)) {\n 791:\t\t\t\tDEV_STATS_INC(dev, tx_carrier_errors);\n 792:\t\t\t\tgoto tx_error;\n 793:\t\t\t}\n 794:\t\t\tif (use_cache)\n 795:\t\t\t\tdst_cache_set_ip4(\u0026tun_info-\u003edst_cache, \u0026rt-\u003edst,\n 796:\t\t\t\t\t\t fl4.saddr);\n 797:\t\t\telse if (!md \u0026\u0026 connected)\n 798:\t\t\t\tdst_cache_set_ip4(\u0026tunnel-\u003edst_cache, \u0026rt-\u003edst,\n 799:\t\t\t\t\t\t fl4.saddr);\n 800:\t\t}\n 801:\t\n 802:\t\tif (rt-\u003edst.dev == dev) {\n 803:\t\t\tip_rt_put(rt);\n 804:\t\t\tDEV_STATS_INC(dev, collisions);\n 805:\t\t\tgoto tx_error;\n 806:\t\t}\n 807:\t\n 808:\t\tdf = tnl_params-\u003efrag_off;\n 809:\t\tif (payload_protocol == htons(ETH_P_IP) \u0026\u0026 !tunnel-\u003eignore_df)\n 810:\t\t\tdf |= (inner_iph-\u003efrag_off \u0026 htons(IP_DF));\n 811:\t\n 812:\t\tif (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false,\n 813:\t\t\t\t encap_hlen)) {\n 814:\t\t\tip_rt_put(rt);\n 815:\t\t\tgoto tx_error;\n 816:\t\t}\n 817:\t\n 818:\t\terr_count = READ_ONCE(tunnel-\u003eerr_count);\n 819:\t\tif (err_count \u003e 0) {\n 820:\t\t\tif (time_before(jiffies,\n 821:\t\t\t\t\tREAD_ONCE(tunnel-\u003eerr_time) + IPTUNNEL_ERR_TIMEO)) {\n 822:\t\t\t\tWRITE_ONCE(tunnel-\u003eerr_count, err_count - 1);\n 823:\t\n 824:\t\t\t\tdst_link_failure(skb);\n 825:\t\t\t} else {\n 826:\t\t\t\tWRITE_ONCE(tunnel-\u003eerr_count, 0);\n 827:\t\t\t}\n 828:\t\t}\n 829:\t\n 830:\t\ttos = ip_tunnel_ecn_encap(tos, inner_iph, skb);\n 831:\t\tttl = tnl_params-\u003ettl;\n 832:\t\tif (ttl == 0) {\n 833:\t\t\tif (payload_protocol == htons(ETH_P_IP))\n 834:\t\t\t\tttl = inner_iph-\u003ettl;\n 835:\t#if IS_ENABLED(CONFIG_IPV6)\n 836:\t\t\telse if (payload_protocol == htons(ETH_P_IPV6))\n 837:\t\t\t\tttl = ((const struct ipv6hdr *)inner_iph)-\u003ehop_limit;\n 838:\t#endif\n 839:\t\t\telse\n 840:\t\t\t\tttl = ip4_dst_hoplimit(\u0026rt-\u003edst);\n 841:\t\t}\n 842:\t\n 843:\t\tmax_headroom = LL_RESERVED_SPACE(rt-\u003edst.dev) + sizeof(struct iphdr)\n 844:\t\t\t\t+ rt-\u003edst.header_len + encap_hlen;\n 845:\t\n 846:\t\tif (skb_cow_head(skb, max_headroom)) {\n 847:\t\t\tip_rt_put(rt);\n 848:\t\t\tDEV_STATS_INC(dev, tx_dropped);\n 849:\t\t\tkfree_skb(skb);\n 850:\t\t\treturn;\n 851:\t\t}\n 852:\t\n 853:\t\tip_tunnel_adj_headroom(dev, max_headroom);\n 854:\t\n 855:\t\tif (ip_tunnel_encap(skb, \u0026ipencap, \u0026protocol, \u0026fl4) \u003c 0) {\n 856:\t\t\tip_rt_put(rt);\n 857:\t\t\tgoto tx_error;\n 858:\t\t}\n 859:\t\n"
} |
| 11/2 | 2026/09/06 05:01 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 20379 output: 37 thoughts: 417 Thoughts: **Analyzing Potential IP Tunneling Vulnerabilities** Okay, let's break this down. My initial impression is that we're looking at changes within `net/ipv4/ip_tunnel.c`, which, as we know, is *core* to the kernel's IP tunneling implementation. This covers things like GRE, IPIP, and so on – the fundamental building blocks for virtual network interfaces like `ipgre` and `ipip`. Importantly, this code *is* reachable and executable within the kernel's networking stack. The fact that `WorthFuzzing` is set to TRUE immediately grabs my attention. That confirms our hunch: we need to investigate this thoroughly. Now, let's pinpoint the areas of greatest interest. I'm focusing on the exposed symbols, and the functions being called. `ip_tunnel_xmit`, `tnl_update_pmtu`, and `ip_md_tunnel_xmit` are the immediate targets. `ip_tunnel_xmit` and `ip_md_tunnel_xmit` are *exported*, meaning they can be called from outside the module. Specifically, `EXPORT_SYMBOL_GPL(ip_tunnel_xmit)` and `EXPORT_SYMBOL_GPL(ip_md_tunnel_xmit)` confirm this. `tnl_update_pmtu`, although static, is also interesting since it gets called by `ip_tunnel_xmit` and `ip_md_tunnel_xmit`. The fact that `tnl_update_pmtu` is *modified* is definitely a red flag. This suggests that whatever is happening during PMTU updates, specifically when called within the xmit paths, warrants closer scrutiny. Finally, we need to understand the configuration context. Looking at `net/ipv4/Kconfig`, `CONFIG_NET_IP_TUNNEL` is tristate and selected by the likes of `CONFIG_NET_IPGRE`, `CONFIG_NET_IPIP`, etc. Of course, `CONFIG_INET` is a prerequisite for the entire `net/ipv4` subtree. It's useful that the necessary configurations that directly or indirectly select `NET_IP_TUNNEL` are known. This is critical for fuzzing campaigns and determining potential impact. We now have a good starting point for exploring potential vulnerabilities. |
| 12/2 | 2026/09/06 05:01 | tool | grepper |
0mArgs:{
"Expression": "config NET_IP_TUNNEL|select NET_IP_TUNNEL",
"PathPrefix": "net/"
}Results: {
"Output": "net/ipv4/Kconfig=162=config NET_IPIP\n--\nnet/ipv4/Kconfig-164-\tselect INET_TUNNEL\nnet/ipv4/Kconfig:165:\tselect NET_IP_TUNNEL\nnet/ipv4/Kconfig-166-\thelp\n--\nnet/ipv4/Kconfig=180=config NET_IPGRE_DEMUX\n--\nnet/ipv4/Kconfig-185-\nnet/ipv4/Kconfig:186:config NET_IP_TUNNEL\nnet/ipv4/Kconfig-187-\ttristate\n--\nnet/ipv4/Kconfig=192=config NET_IPGRE\n--\nnet/ipv4/Kconfig-194-\tdepends on NET_IPGRE_DEMUX\nnet/ipv4/Kconfig:195:\tselect NET_IP_TUNNEL\nnet/ipv4/Kconfig-196-\thelp\n--\nnet/ipv4/Kconfig=304=config NET_IPVTI\n--\nnet/ipv4/Kconfig-306-\tselect INET_TUNNEL\nnet/ipv4/Kconfig:307:\tselect NET_IP_TUNNEL\nnet/ipv4/Kconfig-308-\tselect XFRM\n--\nnet/ipv4/Kconfig=316=config NET_UDP_TUNNEL\nnet/ipv4/Kconfig-317-\ttristate\nnet/ipv4/Kconfig:318:\tselect NET_IP_TUNNEL\nnet/ipv4/Kconfig-319-\tdefault n\n--\nnet/ipv6/Kconfig=150=config IPV6_VTI\n--\nnet/ipv6/Kconfig-152-\tselect IPV6_TUNNEL\nnet/ipv6/Kconfig:153:\tselect NET_IP_TUNNEL\nnet/ipv6/Kconfig-154-\tselect XFRM\n--\nnet/ipv6/Kconfig=162=config IPV6_SIT\n--\nnet/ipv6/Kconfig-164-\tselect INET_TUNNEL\nnet/ipv6/Kconfig:165:\tselect NET_IP_TUNNEL\nnet/ipv6/Kconfig-166-\tselect IPV6_NDISC_NODETYPE\n--\nnet/ipv6/Kconfig=210=config IPV6_GRE\n--\nnet/ipv6/Kconfig-212-\tselect IPV6_TUNNEL\nnet/ipv6/Kconfig:213:\tselect NET_IP_TUNNEL\nnet/ipv6/Kconfig-214-\tdepends on NET_IPGRE_DEMUX\n"
} |
| 13/2 | 2026/09/06 05:01 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 21992 output: 181 thoughts: 301 Thoughts: **My Analysis of the Kernel IP Tunnel Configuration** Okay, so I'm diving into this kernel configuration, and it looks like the key players for IP tunnels are centered around a few Kconfig symbols. Specifically, I see that enabling either `NET_IP_TUNNEL`, `NET_IPGRE`, or `NET_IPIP` is crucial. The `NET_IP_TUNNEL` symbol directly links to `net/ipv4/Makefile` where `ip_tunnel.o` is built. Also, I need to keep in mind `NET_IPGRE` and `NET_FOU_IP_TUNNELS`, which leverages encapsulation. I should probably also double-check `NET_FOU` to ensure it, along with `NET_FOU_IP_TUNNELS`, is accounted for. I've got the requirements nailed down: `WorthFuzzing` is true, and the key `EnableConfigs` are `NET_IP_TUNNEL`, `NET_IPGRE`, `NET_IPIP`, and `NET_FOU_IP_TUNNELS`. The focus for deeper investigation should be on `FocusSymbols`: `ip_tunnel_xmit`, `ip_md_tunnel_xmit`, and `tnl_update_pmtu`. I'm making sure that these functions make sense in relation to one another. I need to perform a quick check, to ensure `tnl_update_pmtu` is actually a symbol in `ip_tunnel.o`, unless, of course, it's inlined. Even if it's inlined, I'm confident that `ip_tunnel_xmit` and `ip_md_tunnel_xmit` will be exported functions that call it. Okay, that's the core of the analysis. Time to invoke `set-results`. |
| 14/2 | 2026/09/06 05:01 | tool | set-results |
0mArgs:{
"EnableConfigs": [
"NET_IP_TUNNEL",
"NET_IPGRE",
"NET_IPIP",
"NET_FOU_IP_TUNNELS"
],
"FocusSymbols": [
"ip_tunnel_xmit",
"ip_md_tunnel_xmit",
"tnl_update_pmtu"
],
"Reasoning": "The patch modifies PMTU calculation and tunnel encapsulation handling during packet transmission in the IP tunneling subsystem (net/ipv4/ip_tunnel.c). It snapshots the tunnel encapsulation configuration to prevent data races during concurrent changelink operations, defers encapsulation in ip_tunnel_xmit, and accounts for encap header length in PMTU updates. These changes affect reachable core networking paths accessible via virtual tunnel devices and netlink configuration.",
"WorthFuzzing": true
}Results: {
"EnableConfigs": [
"NET_IP_TUNNEL",
"NET_IPGRE",
"NET_IPIP",
"NET_FOU_IP_TUNNELS"
],
"FocusSymbols": [
"ip_tunnel_xmit",
"ip_md_tunnel_xmit",
"tnl_update_pmtu"
],
"Reasoning": "The patch modifies PMTU calculation and tunnel encapsulation handling during packet transmission in the IP tunneling subsystem (net/ipv4/ip_tunnel.c). It snapshots the tunnel encapsulation configuration to prevent data races during concurrent changelink operations, defers encapsulation in ip_tunnel_xmit, and accounts for encap header length in PMTU updates. These changes affect reachable core networking paths accessible via virtual tunnel devices and netlink configuration.",
"WorthFuzzing": true
} |
| 15/1 | 2026/09/06 05:01 | action | If |
0mArgs:{
"WorthFuzzing": true
}Results: null |
| 16/2 | 2026/09/06 05:01 | agent | kmsan-evaluator |
0mModel:core Args: null Results: {
"KMSANReasoning": "The patch addresses data races and PMTU/headroom calculations in IPv4 tunnel transmission (ip_tunnel_xmit and tnl_update_pmtu). Specifically:\n1. It snapshots `tunnel-\u003eencap` into a stack variable `ipencap` using `data_race()` to prevent concurrent modification by `ipgre_changelink()`.\n2. It accounts for `encap_hlen` in `tnl_update_pmtu` and defers calling `ip_tunnel_encap()` until after skb headroom is expanded with `skb_cow_head()`.\n\nRegarding sanitizers:\n- Memory safety bugs related to buffer headroom, skb bounds, and use-after-free are covered by KASAN.\n- Concurrency issues and data races are targeted by KCSAN/LOCKDEP.\n- The local variable `ipencap` is fully initialized via structure assignment before any read, `encap_hlen` is an integer initialized with the return value of `ip_encap_hlen()`, and no kernel memory is copied to user space. There is no risk of uninitialized memory reads or information leaks.\n\nTherefore, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
}Instruction: You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.
CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
a comprehensive suite of debugging tools and sanitizers, including KASAN
(out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
(locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
or page allocations) and kernel-to-user memory info-leaks.
Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.
Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.
Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
attributes, ioctl output arguments, socket options, or BPF buffers) where fields
or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
uninitialized bytes of existing buffers.
Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
dereferences, locking deadlocks, or use-after-free bugs (these are already caught
by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.
Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
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: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit 50193a517faf720149ee924eb5dab7e1eccaf706
Author: syz-cluster <triage@syzkaller.com>
Date: Sun Sep 6 05:01:08 2026 +0000
syz-cluster: applied patch under review
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 9d114bd575f92..447b435b10cca 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -512,14 +512,15 @@ EXPORT_SYMBOL_GPL(ip_tunnel_encap_setup);
static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,
struct rtable *rt, __be16 df,
const struct iphdr *inner_iph,
- int tunnel_hlen, __be32 dst, bool md)
+ int tunnel_hlen, __be32 dst, bool md,
+ int encap_hlen)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
int pkt_size;
int mtu;
tunnel_hlen = md ? tunnel_hlen : tunnel->hlen;
- pkt_size = skb->len - tunnel_hlen;
+ pkt_size = skb->len + encap_hlen - tunnel_hlen;
pkt_size -= dev->type == ARPHRD_ETHER ? dev->hard_header_len : 0;
if (df) {
@@ -629,7 +630,7 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
if (test_bit(IP_TUNNEL_DONT_FRAGMENT_BIT, key->tun_flags))
df = htons(IP_DF);
if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, tunnel_hlen,
- key->u.ipv4.dst, true)) {
+ key->u.ipv4.dst, true, 0)) {
ip_rt_put(rt);
goto tx_error;
}
@@ -671,6 +672,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
{
struct ip_tunnel *tunnel = netdev_priv(dev);
struct ip_tunnel_info *tun_info = NULL;
+ struct ip_tunnel_encap ipencap;
const struct iphdr *inner_iph;
unsigned int max_headroom; /* The extra header space needed */
struct rtable *rt = NULL; /* Route to the other host */
@@ -680,6 +682,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
bool md = false;
bool connected;
int err_count;
+ int encap_hlen;
u8 tos, ttl;
__be32 dst;
__be16 df;
@@ -765,7 +768,10 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
tunnel->net, READ_ONCE(tunnel->parms.link),
tunnel->fwmark, skb_get_hash(skb), 0);
- if (ip_tunnel_encap(skb, &tunnel->encap, &protocol, &fl4) < 0)
+ /* Snapshot encap; ipgre_changelink() can update it concurrently. */
+ ipencap = data_race(tunnel->encap);
+ encap_hlen = ip_encap_hlen(&ipencap);
+ if (encap_hlen < 0)
goto tx_error;
if (connected && md) {
@@ -803,7 +809,8 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
if (payload_protocol == htons(ETH_P_IP) && !tunnel->ignore_df)
df |= (inner_iph->frag_off & htons(IP_DF));
- if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false)) {
+ if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false,
+ encap_hlen)) {
ip_rt_put(rt);
goto tx_error;
}
@@ -834,7 +841,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
}
max_headroom = LL_RESERVED_SPACE(rt->dst.dev) + sizeof(struct iphdr)
- + rt->dst.header_len + ip_encap_hlen(&tunnel->encap);
+ + rt->dst.header_len + encap_hlen;
if (skb_cow_head(skb, max_headroom)) {
ip_rt_put(rt);
@@ -845,6 +852,11 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
ip_tunnel_adj_headroom(dev, max_headroom);
+ if (ip_tunnel_encap(skb, &ipencap, &protocol, &fl4) < 0) {
+ ip_rt_put(rt);
+ goto tx_error;
+ }
+
iptunnel_xmit(NULL, rt, skb, fl4.saddr, fl4.daddr, protocol, tos, ttl,
df, !net_eq(tunnel->net, dev_net(dev)), 0);
return;
|
| 17/3 | 2026/09/06 05:01 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 3334 output: 39 thoughts: 81 Thoughts: Here's my assessment of the situation: **KMSAN Fuzzing Consideration** Okay, so the task at hand is to determine if this kernel patch justifies firing up a KMSAN fuzzing session, beyond the usual KASAN checks. Let's dig in. My first instinct is to dive into the patch diff, paying close attention to the context around that `net/ipv4/ip_tunnel.c` file. I'll need to understand what's being modified, *why*, and what the potential implications are for memory safety. I'm thinking I'll start with either `read-file` or `grepper` – whatever's fastest and most efficient – to get a solid grasp of `net/ipv4/ip_tunnel.c` itself. I need to refresh my understanding of that part of the networking stack before I can even begin to assess the impact of the patch. Knowing that code like the back of my hand will provide the necessary context to determine if KMSAN fuzzing is warranted, or if KASAN alone is sufficient. I need to quickly identify the potential for uninitialized memory reads. |
| 18/3 | 2026/09/06 05:01 | tool | read-file |
0mArgs:{
"File": "net/ipv4/ip_tunnel.c",
"FirstLine": 750,
"LineCount": 100
}Results: {
"Contents": " 750:\t\t\tif (!md)\n 751:\t\t\t\tconnected = false;\n 752:\t\t}\n 753:\t\n 754:\t\ttos = tnl_params-\u003etos;\n 755:\t\tif (tos \u0026 0x1) {\n 756:\t\t\ttos \u0026= ~0x1;\n 757:\t\t\tif (payload_protocol == htons(ETH_P_IP)) {\n 758:\t\t\t\ttos = inner_iph-\u003etos;\n 759:\t\t\t\tconnected = false;\n 760:\t\t\t} else if (payload_protocol == htons(ETH_P_IPV6)) {\n 761:\t\t\t\ttos = ipv6_get_dsfield((const struct ipv6hdr *)inner_iph);\n 762:\t\t\t\tconnected = false;\n 763:\t\t\t}\n 764:\t\t}\n 765:\t\n 766:\t\tip_tunnel_init_flow(\u0026fl4, protocol, dst, tnl_params-\u003esaddr,\n 767:\t\t\t\t tunnel-\u003eparms.o_key, tos \u0026 INET_DSCP_MASK,\n 768:\t\t\t\t tunnel-\u003enet, READ_ONCE(tunnel-\u003eparms.link),\n 769:\t\t\t\t tunnel-\u003efwmark, skb_get_hash(skb), 0);\n 770:\t\n 771:\t\t/* Snapshot encap; ipgre_changelink() can update it concurrently. */\n 772:\t\tipencap = data_race(tunnel-\u003eencap);\n 773:\t\tencap_hlen = ip_encap_hlen(\u0026ipencap);\n 774:\t\tif (encap_hlen \u003c 0)\n 775:\t\t\tgoto tx_error;\n 776:\t\n 777:\t\tif (connected \u0026\u0026 md) {\n 778:\t\t\tuse_cache = ip_tunnel_dst_cache_usable(skb, tun_info);\n 779:\t\t\tif (use_cache)\n 780:\t\t\t\trt = dst_cache_get_ip4(\u0026tun_info-\u003edst_cache,\n 781:\t\t\t\t\t\t \u0026fl4.saddr);\n 782:\t\t} else {\n 783:\t\t\trt = connected ? dst_cache_get_ip4(\u0026tunnel-\u003edst_cache,\n 784:\t\t\t\t\t\t\t\u0026fl4.saddr) : NULL;\n 785:\t\t}\n 786:\t\n 787:\t\tif (!rt) {\n 788:\t\t\trt = ip_route_output_key(tunnel-\u003enet, \u0026fl4);\n 789:\t\n 790:\t\t\tif (IS_ERR(rt)) {\n 791:\t\t\t\tDEV_STATS_INC(dev, tx_carrier_errors);\n 792:\t\t\t\tgoto tx_error;\n 793:\t\t\t}\n 794:\t\t\tif (use_cache)\n 795:\t\t\t\tdst_cache_set_ip4(\u0026tun_info-\u003edst_cache, \u0026rt-\u003edst,\n 796:\t\t\t\t\t\t fl4.saddr);\n 797:\t\t\telse if (!md \u0026\u0026 connected)\n 798:\t\t\t\tdst_cache_set_ip4(\u0026tunnel-\u003edst_cache, \u0026rt-\u003edst,\n 799:\t\t\t\t\t\t fl4.saddr);\n 800:\t\t}\n 801:\t\n 802:\t\tif (rt-\u003edst.dev == dev) {\n 803:\t\t\tip_rt_put(rt);\n 804:\t\t\tDEV_STATS_INC(dev, collisions);\n 805:\t\t\tgoto tx_error;\n 806:\t\t}\n 807:\t\n 808:\t\tdf = tnl_params-\u003efrag_off;\n 809:\t\tif (payload_protocol == htons(ETH_P_IP) \u0026\u0026 !tunnel-\u003eignore_df)\n 810:\t\t\tdf |= (inner_iph-\u003efrag_off \u0026 htons(IP_DF));\n 811:\t\n 812:\t\tif (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false,\n 813:\t\t\t\t encap_hlen)) {\n 814:\t\t\tip_rt_put(rt);\n 815:\t\t\tgoto tx_error;\n 816:\t\t}\n 817:\t\n 818:\t\terr_count = READ_ONCE(tunnel-\u003eerr_count);\n 819:\t\tif (err_count \u003e 0) {\n 820:\t\t\tif (time_before(jiffies,\n 821:\t\t\t\t\tREAD_ONCE(tunnel-\u003eerr_time) + IPTUNNEL_ERR_TIMEO)) {\n 822:\t\t\t\tWRITE_ONCE(tunnel-\u003eerr_count, err_count - 1);\n 823:\t\n 824:\t\t\t\tdst_link_failure(skb);\n 825:\t\t\t} else {\n 826:\t\t\t\tWRITE_ONCE(tunnel-\u003eerr_count, 0);\n 827:\t\t\t}\n 828:\t\t}\n 829:\t\n 830:\t\ttos = ip_tunnel_ecn_encap(tos, inner_iph, skb);\n 831:\t\tttl = tnl_params-\u003ettl;\n 832:\t\tif (ttl == 0) {\n 833:\t\t\tif (payload_protocol == htons(ETH_P_IP))\n 834:\t\t\t\tttl = inner_iph-\u003ettl;\n 835:\t#if IS_ENABLED(CONFIG_IPV6)\n 836:\t\t\telse if (payload_protocol == htons(ETH_P_IPV6))\n 837:\t\t\t\tttl = ((const struct ipv6hdr *)inner_iph)-\u003ehop_limit;\n 838:\t#endif\n 839:\t\t\telse\n 840:\t\t\t\tttl = ip4_dst_hoplimit(\u0026rt-\u003edst);\n 841:\t\t}\n 842:\t\n 843:\t\tmax_headroom = LL_RESERVED_SPACE(rt-\u003edst.dev) + sizeof(struct iphdr)\n 844:\t\t\t\t+ rt-\u003edst.header_len + encap_hlen;\n 845:\t\n 846:\t\tif (skb_cow_head(skb, max_headroom)) {\n 847:\t\t\tip_rt_put(rt);\n 848:\t\t\tDEV_STATS_INC(dev, tx_dropped);\n 849:\t\t\tkfree_skb(skb);\n"
} |
| 19/3 | 2026/09/06 05:01 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 5316 output: 38 thoughts: 26 Thoughts: Here's my summary, as if I were the one thinking these thoughts, geared towards an expert: **Investigating `tnl_update_pmtu` in Context** Alright, let's dive into this. I'm thinking we should zero in on lines 510-550 to get a good handle on `tnl_update_pmtu`. This function is likely the linchpin for adjusting PMTU values in a tunnel context, so understanding its logic is crucial for troubleshooting any MTU-related issues or optimizing tunnel performance. I want to see how it interacts with the underlying network interfaces, how it handles fragmentation, and, especially given my background, how it deals with path MTU discovery and any related error handling. I'm anticipating this function is where all the PMTU "magic" happens. Given the code's complexity, I'll pay close attention to the use of any locking mechanisms and concurrency considerations, especially if we have multiple tunnel instances. My expert eye will be laser-focused on potential race conditions or performance bottlenecks within that particular section. |
| 20/3 | 2026/09/06 05:01 | tool | read-file |
0mArgs:{
"File": "net/ipv4/ip_tunnel.c",
"FirstLine": 510,
"LineCount": 50
}Results: {
"Contents": " 510:\tEXPORT_SYMBOL_GPL(ip_tunnel_encap_setup);\n 511:\t\n 512:\tstatic int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb,\n 513:\t\t\t\t struct rtable *rt, __be16 df,\n 514:\t\t\t\t const struct iphdr *inner_iph,\n 515:\t\t\t\t int tunnel_hlen, __be32 dst, bool md,\n 516:\t\t\t\t int encap_hlen)\n 517:\t{\n 518:\t\tstruct ip_tunnel *tunnel = netdev_priv(dev);\n 519:\t\tint pkt_size;\n 520:\t\tint mtu;\n 521:\t\n 522:\t\ttunnel_hlen = md ? tunnel_hlen : tunnel-\u003ehlen;\n 523:\t\tpkt_size = skb-\u003elen + encap_hlen - tunnel_hlen;\n 524:\t\tpkt_size -= dev-\u003etype == ARPHRD_ETHER ? dev-\u003ehard_header_len : 0;\n 525:\t\n 526:\t\tif (df) {\n 527:\t\t\tmtu = dst_mtu(\u0026rt-\u003edst) - (sizeof(struct iphdr) + tunnel_hlen);\n 528:\t\t\tmtu -= dev-\u003etype == ARPHRD_ETHER ? dev-\u003ehard_header_len : 0;\n 529:\t\t} else {\n 530:\t\t\tmtu = skb_valid_dst(skb) ? dst_mtu(skb_dst(skb)) : dev-\u003emtu;\n 531:\t\t}\n 532:\t\n 533:\t\tif (skb_valid_dst(skb))\n 534:\t\t\tskb_dst_update_pmtu_no_confirm(skb, mtu);\n 535:\t\n 536:\t\tif (skb-\u003eprotocol == htons(ETH_P_IP)) {\n 537:\t\t\tif (!skb_is_gso(skb) \u0026\u0026\n 538:\t\t\t (inner_iph-\u003efrag_off \u0026 htons(IP_DF)) \u0026\u0026\n 539:\t\t\t mtu \u003c pkt_size) {\n 540:\t\t\t\ticmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));\n 541:\t\t\t\treturn -E2BIG;\n 542:\t\t\t}\n 543:\t\t}\n 544:\t#if IS_ENABLED(CONFIG_IPV6)\n 545:\t\telse if (skb-\u003eprotocol == htons(ETH_P_IPV6)) {\n 546:\t\t\tstruct rt6_info *rt6;\n 547:\t\t\t__be32 daddr;\n 548:\t\n 549:\t\t\trt6 = skb_valid_dst(skb) ? dst_rt6_info(skb_dst(skb)) :\n 550:\t\t\t\t\t\t NULL;\n 551:\t\t\tdaddr = md ? dst : tunnel-\u003eparms.iph.daddr;\n 552:\t\n 553:\t\t\tif (rt6 \u0026\u0026 mtu \u003c dst_mtu(skb_dst(skb)) \u0026\u0026\n 554:\t\t\t\t mtu \u003e= IPV6_MIN_MTU) {\n 555:\t\t\t\tif ((daddr \u0026\u0026 !ipv4_is_multicast(daddr)) ||\n 556:\t\t\t\t rt6-\u003ert6i_dst.plen == 128) {\n 557:\t\t\t\t\trt6-\u003ert6i_flags |= RTF_MODIFIED;\n 558:\t\t\t\t\tdst_metric_set(skb_dst(skb), RTAX_MTU, mtu);\n 559:\t\t\t\t}\n"
} |
| 21/3 | 2026/09/06 05:01 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 6555 output: 38 thoughts: 36 Thoughts: Okay, here's my interpretation of those thoughts, presented as my own mental process, given my expertise: **Diving into the Commit Details** Alright, time to dissect this commit. My first thought is always to understand the *why* behind the *what*. I need to immediately grasp the problem this addresses. I'm looking beyond the code; what was the trigger? What's the impact on the system? Performance, security, specific functionality? That's the baseline. Now, let's get into the specifics. My focus is immediately drawn to the `ip_tunnel_encap` and `ip_encap_hlen` variables or functions (or whatever this specific system uses). These are likely key elements, given their mention. They almost certainly relate to some form of IP encapsulation, probably related to tunneling. I need to understand how the changes here are affecting those functions/variables. Any modifications to those areas are critical to the overall changes. Are we dealing with header size issues? Any potential fragmentation changes? Encryption concerns? What's the context in which these are used, and how does this update interact? It all boils down to the low-level details of how packets are handled, and that's where I need to start. |
| 22/3 | 2026/09/06 05:01 | tool | grepper |
0mArgs:{
"Expression": "ip_encap_hlen|ip_tunnel_encap",
"PathPrefix": "net/ipv4/"
}Results: {
"Output": "net/ipv4/fou_core.c=903=static struct genl_family fou_nl_family __ro_after_init = {\n--\nnet/ipv4/fou_core.c-915-\nnet/ipv4/fou_core.c:916:size_t fou_encap_hlen(struct ip_tunnel_encap *e)\nnet/ipv4/fou_core.c-917-{\n--\nnet/ipv4/fou_core.c=920=EXPORT_SYMBOL(fou_encap_hlen);\nnet/ipv4/fou_core.c-921-\nnet/ipv4/fou_core.c:922:size_t gue_encap_hlen(struct ip_tunnel_encap *e)\nnet/ipv4/fou_core.c-923-{\n--\nnet/ipv4/fou_core.c=938=EXPORT_SYMBOL(gue_encap_hlen);\nnet/ipv4/fou_core.c-939-\nnet/ipv4/fou_core.c:940:int __fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-941-\t\t u8 *protocol, __be16 *sport, int type)\n--\nnet/ipv4/fou_core.c=954=EXPORT_SYMBOL(__fou_build_header);\nnet/ipv4/fou_core.c-955-\nnet/ipv4/fou_core.c:956:int __gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-957-\t\t u8 *protocol, __be16 *sport, int type)\n--\nnet/ipv4/fou_core.c=1027=EXPORT_SYMBOL(__gue_build_header);\n--\nnet/ipv4/fou_core.c-1030-\nnet/ipv4/fou_core.c:1031:static void fou_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-1032-\t\t\t struct flowi4 *fl4, u8 *protocol, __be16 sport)\n--\nnet/ipv4/fou_core.c-1049-\nnet/ipv4/fou_core.c:1050:static int fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-1051-\t\t\t u8 *protocol, struct flowi4 *fl4)\n--\nnet/ipv4/fou_core.c-1066-\nnet/ipv4/fou_core.c:1067:static int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,\nnet/ipv4/fou_core.c-1068-\t\t\t u8 *protocol, struct flowi4 *fl4)\n--\nnet/ipv4/fou_core.c=1096=static int gue_err(struct sk_buff *skb, u32 info)\n--\nnet/ipv4/fou_core.c-1161-\nnet/ipv4/fou_core.c:1162:static const struct ip_tunnel_encap_ops fou_iptun_ops = {\nnet/ipv4/fou_core.c-1163-\t.encap_hlen = fou_encap_hlen,\n--\nnet/ipv4/fou_core.c-1167-\nnet/ipv4/fou_core.c:1168:static const struct ip_tunnel_encap_ops gue_iptun_ops = {\nnet/ipv4/fou_core.c-1169-\t.encap_hlen = gue_encap_hlen,\n--\nnet/ipv4/fou_core.c-1173-\nnet/ipv4/fou_core.c:1174:static int ip_tunnel_encap_add_fou_ops(void)\nnet/ipv4/fou_core.c-1175-{\n--\nnet/ipv4/fou_core.c-1177-\nnet/ipv4/fou_core.c:1178:\tret = ip_tunnel_encap_add_ops(\u0026fou_iptun_ops, TUNNEL_ENCAP_FOU);\nnet/ipv4/fou_core.c-1179-\tif (ret \u003c 0) {\n--\nnet/ipv4/fou_core.c-1183-\nnet/ipv4/fou_core.c:1184:\tret = ip_tunnel_encap_add_ops(\u0026gue_iptun_ops, TUNNEL_ENCAP_GUE);\nnet/ipv4/fou_core.c-1185-\tif (ret \u003c 0) {\nnet/ipv4/fou_core.c-1186-\t\tpr_err(\"can't add gue ops\\n\");\nnet/ipv4/fou_core.c:1187:\t\tip_tunnel_encap_del_ops(\u0026fou_iptun_ops, TUNNEL_ENCAP_FOU);\nnet/ipv4/fou_core.c-1188-\t\treturn ret;\n--\nnet/ipv4/fou_core.c-1193-\nnet/ipv4/fou_core.c:1194:static void ip_tunnel_encap_del_fou_ops(void)\nnet/ipv4/fou_core.c-1195-{\nnet/ipv4/fou_core.c:1196:\tip_tunnel_encap_del_ops(\u0026fou_iptun_ops, TUNNEL_ENCAP_FOU);\nnet/ipv4/fou_core.c:1197:\tip_tunnel_encap_del_ops(\u0026gue_iptun_ops, TUNNEL_ENCAP_GUE);\nnet/ipv4/fou_core.c-1198-}\n--\nnet/ipv4/fou_core.c-1201-\nnet/ipv4/fou_core.c:1202:static int ip_tunnel_encap_add_fou_ops(void)\nnet/ipv4/fou_core.c-1203-{\n--\nnet/ipv4/fou_core.c-1206-\nnet/ipv4/fou_core.c:1207:static void ip_tunnel_encap_del_fou_ops(void)\nnet/ipv4/fou_core.c-1208-{\n--\nnet/ipv4/fou_core.c=1241=static int __init fou_init(void)\n--\nnet/ipv4/fou_core.c-1256-\nnet/ipv4/fou_core.c:1257:\tret = ip_tunnel_encap_add_fou_ops();\nnet/ipv4/fou_core.c-1258-\tif (ret == 0)\n--\nnet/ipv4/fou_core.c=1269=static void __exit fou_fini(void)\nnet/ipv4/fou_core.c-1270-{\nnet/ipv4/fou_core.c:1271:\tip_tunnel_encap_del_fou_ops();\nnet/ipv4/fou_core.c-1272-\tgenl_unregister_family(\u0026fou_nl_family);\n--\nnet/ipv4/ip_gre.c=1296=static bool ipgre_netlink_encap_parms(struct nlattr *data[],\nnet/ipv4/ip_gre.c:1297:\t\t\t\t struct ip_tunnel_encap *ipencap)\nnet/ipv4/ip_gre.c-1298-{\n--\nnet/ipv4/ip_gre.c=1394=ipgre_newlink_encap_setup(struct net_device *dev, struct nlattr *data[])\nnet/ipv4/ip_gre.c-1395-{\nnet/ipv4/ip_gre.c:1396:\tstruct ip_tunnel_encap ipencap;\nnet/ipv4/ip_gre.c-1397-\n--\nnet/ipv4/ip_gre.c-1399-\t\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ip_gre.c:1400:\t\tint err = ip_tunnel_encap_setup(t, \u0026ipencap);\nnet/ipv4/ip_gre.c-1401-\n--\nnet/ipv4/ip_tunnel.c=457=EXPORT_SYMBOL_GPL(ip_tunnel_rcv);\nnet/ipv4/ip_tunnel.c-458-\nnet/ipv4/ip_tunnel.c:459:int ip_tunnel_encap_add_ops(const struct ip_tunnel_encap_ops *ops,\nnet/ipv4/ip_tunnel.c-460-\t\t\t unsigned int num)\n--\nnet/ipv4/ip_tunnel.c-464-\nnet/ipv4/ip_tunnel.c:465:\treturn !cmpxchg((const struct ip_tunnel_encap_ops **)\nnet/ipv4/ip_tunnel.c-466-\t\t\t\u0026iptun_encaps[num],\n--\nnet/ipv4/ip_tunnel.c-468-}\nnet/ipv4/ip_tunnel.c:469:EXPORT_SYMBOL(ip_tunnel_encap_add_ops);\nnet/ipv4/ip_tunnel.c-470-\nnet/ipv4/ip_tunnel.c:471:int ip_tunnel_encap_del_ops(const struct ip_tunnel_encap_ops *ops,\nnet/ipv4/ip_tunnel.c-472-\t\t\t unsigned int num)\n--\nnet/ipv4/ip_tunnel.c-478-\nnet/ipv4/ip_tunnel.c:479:\tret = (cmpxchg((const struct ip_tunnel_encap_ops **)\nnet/ipv4/ip_tunnel.c-480-\t\t \u0026iptun_encaps[num],\n--\nnet/ipv4/ip_tunnel.c-486-}\nnet/ipv4/ip_tunnel.c:487:EXPORT_SYMBOL(ip_tunnel_encap_del_ops);\nnet/ipv4/ip_tunnel.c-488-\nnet/ipv4/ip_tunnel.c:489:int ip_tunnel_encap_setup(struct ip_tunnel *t,\nnet/ipv4/ip_tunnel.c:490:\t\t\t struct ip_tunnel_encap *ipencap)\nnet/ipv4/ip_tunnel.c-491-{\n--\nnet/ipv4/ip_tunnel.c-495-\nnet/ipv4/ip_tunnel.c:496:\thlen = ip_encap_hlen(ipencap);\nnet/ipv4/ip_tunnel.c-497-\tif (hlen \u003c 0)\n--\nnet/ipv4/ip_tunnel.c-509-}\nnet/ipv4/ip_tunnel.c:510:EXPORT_SYMBOL_GPL(ip_tunnel_encap_setup);\nnet/ipv4/ip_tunnel.c-511-\n--\nnet/ipv4/ip_tunnel.c=572=void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n--\nnet/ipv4/ip_tunnel.c-605-\tif (!tunnel_hlen)\nnet/ipv4/ip_tunnel.c:606:\t\ttunnel_hlen = ip_encap_hlen(\u0026tun_info-\u003eencap);\nnet/ipv4/ip_tunnel.c-607-\nnet/ipv4/ip_tunnel.c:608:\tif (ip_tunnel_encap(skb, \u0026tun_info-\u003eencap, \u0026proto, \u0026fl4) \u003c 0)\nnet/ipv4/ip_tunnel.c-609-\t\tgoto tx_error;\n--\nnet/ipv4/ip_tunnel.c=670=void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,\n--\nnet/ipv4/ip_tunnel.c-674-\tstruct ip_tunnel_info *tun_info = NULL;\nnet/ipv4/ip_tunnel.c:675:\tstruct ip_tunnel_encap ipencap;\nnet/ipv4/ip_tunnel.c-676-\tconst struct iphdr *inner_iph;\n--\nnet/ipv4/ip_tunnel.c-772-\tipencap = data_race(tunnel-\u003eencap);\nnet/ipv4/ip_tunnel.c:773:\tencap_hlen = ip_encap_hlen(\u0026ipencap);\nnet/ipv4/ip_tunnel.c-774-\tif (encap_hlen \u003c 0)\n--\nnet/ipv4/ip_tunnel.c-854-\nnet/ipv4/ip_tunnel.c:855:\tif (ip_tunnel_encap(skb, \u0026ipencap, \u0026protocol, \u0026fl4) \u003c 0) {\nnet/ipv4/ip_tunnel.c-856-\t\tip_rt_put(rt);\n--\nnet/ipv4/ip_tunnel_core.c-41-\nnet/ipv4/ip_tunnel_core.c:42:const struct ip_tunnel_encap_ops __rcu *\nnet/ipv4/ip_tunnel_core.c-43-\t\tiptun_encaps[MAX_IPTUN_ENCAP_OPS] __read_mostly;\n--\nnet/ipv4/ip_tunnel_core.c=1129=bool ip_tunnel_netlink_encap_parms(struct nlattr *data[],\nnet/ipv4/ip_tunnel_core.c:1130:\t\t\t\t struct ip_tunnel_encap *encap)\nnet/ipv4/ip_tunnel_core.c-1131-{\n--\nnet/ipv4/ipip.c=464=static int ipip_newlink(struct net_device *dev,\n--\nnet/ipv4/ipip.c-470-\tstruct nlattr **tb = params-\u003etb;\nnet/ipv4/ipip.c:471:\tstruct ip_tunnel_encap ipencap;\nnet/ipv4/ipip.c-472-\tstruct ip_tunnel_parm_kern p;\n--\nnet/ipv4/ipip.c-475-\tif (ip_tunnel_netlink_encap_parms(data, \u0026ipencap)) {\nnet/ipv4/ipip.c:476:\t\tint err = ip_tunnel_encap_setup(t, \u0026ipencap);\nnet/ipv4/ipip.c-477-\n--\nnet/ipv4/ipip.c=487=static int ipip_changelink(struct net_device *dev, struct nlattr *tb[],\n--\nnet/ipv4/ipip.c-491-\tstruct ip_tunnel *t = netdev_priv(dev);\nnet/ipv4/ipip.c:492:\tstruct ip_tunnel_encap ipencap;\nnet/ipv4/ipip.c-493-\tstruct ip_tunnel_parm_kern p;\n--\nnet/ipv4/ipip.c-497-\tif (ip_tunnel_netlink_encap_parms(data, \u0026ipencap)) {\nnet/ipv4/ipip.c:498:\t\tint err = ip_tunnel_encap_setup(t, \u0026ipencap);\nnet/ipv4/ipip.c-499-\n--\nnet/ipv4/udp.c=817=static int __udp4_lib_err_encap_no_sk(struct sk_buff *skb, u32 info)\n--\nnet/ipv4/udp.c-822-\t\tint (*handler)(struct sk_buff *skb, u32 info);\nnet/ipv4/udp.c:823:\t\tconst struct ip_tunnel_encap_ops *encap;\nnet/ipv4/udp.c-824-\n"
} |
| 23/3 | 2026/09/06 05:01 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 10934 output: 29 thoughts: 25 Thoughts: Here's my take on those definitions, pulling from my expert knowledge of network encapsulation: **Deciphering `ip_encap_hlen` and `ip_tunnel_encap`** Okay, so I'm looking at `ip_encap_hlen` and `ip_tunnel_encap`. Right off the bat, I know these are likely core components of IP encapsulation, and my spidey senses are tingling - it's probably related to how we handle adding headers and framing data for tunneling and other encapsulation scenarios. `ip_encap_hlen` immediately signals "header length". I'm betting this is a value, probably an integer, that tells the IP stack *exactly* how many bytes need to be prepended to the original packet when it's being encapsulated. This is critical for the upper layers to calculate checksums and properly interpret the incoming data. I'm thinking it’ll be used at both the sending and receiving sides. Then there's `ip_tunnel_encap`. This screams "tunnel encapsulation," of course! It's probably a structure or a function pointer, if I were to guess, that handles the actual process of constructing the tunnel headers. It might include things like adding the outer IP header (if it's an IP-in-IP tunnel), GRE headers, or other encapsulation-specific fields. I’d expect this to be the workhorse that wraps the inner packet in the necessary tunnel framing, effectively hiding the original IP payload and providing a safe passage through some network. I'd imagine that this encapsulates the entire procedure of constructing the new IP packet. I need to see how the code uses these two in conjunction. I wonder if there is an association between the two, such as, the `ip_tunnel_encap` makes use of `ip_encap_hlen` to construct the encapsulation frame. |
| 24/3 | 2026/09/06 05:01 | tool | grepper |
0mArgs:{
"Expression": "ip_tunnel_encap\\(",
"PathPrefix": "include/"
}Results: {
"Output": "include/net/ip_tunnels.h=526=static inline int ip_encap_hlen(struct ip_tunnel_encap *e)\n--\ninclude/net/ip_tunnels.h-545-\ninclude/net/ip_tunnels.h:546:static inline int ip_tunnel_encap(struct sk_buff *skb,\ninclude/net/ip_tunnels.h-547-\t\t\t\t struct ip_tunnel_encap *e,\n"
} |
| 25/3 | 2026/09/06 05:01 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 11510 output: 38 thoughts: 23 Thoughts: Here's a summary of my thought process: **Diving into `ip_tunnels.h`** Okay, time to get my hands dirty. I need to understand something specific about IP tunnels, and the likely place to find relevant definitions is the kernel header file. Let's start with `include/net/ip_tunnels.h`. And I'm going to start around line 520; that's often a good spot to find key data structures or function declarations related to the core functionality, based on my past experience with similar networking code. It's a targeted approach rather than a full code review at this point, which is important given my time. Now, let's see what's there... |
| 26/3 | 2026/09/06 05:01 | tool | read-file |
0mArgs:{
"File": "include/net/ip_tunnels.h",
"FirstLine": 515,
"LineCount": 45
}Results: {
"Contents": " 515:\t\t * a base network header in skb-\u003ehead.\n 516:\t\t */\n 517:\t\treason = pskb_may_pull_reason(skb, maclen + nhlen);\n 518:\t\tif (reason)\n 519:\t\t\treturn reason;\n 520:\t\n 521:\t\tskb_set_network_header(skb, maclen);\n 522:\t\n 523:\t\treturn SKB_NOT_DROPPED_YET;\n 524:\t}\n 525:\t\n 526:\tstatic inline int ip_encap_hlen(struct ip_tunnel_encap *e)\n 527:\t{\n 528:\t\tconst struct ip_tunnel_encap_ops *ops;\n 529:\t\tint hlen = -EINVAL;\n 530:\t\n 531:\t\tif (e-\u003etype == TUNNEL_ENCAP_NONE)\n 532:\t\t\treturn 0;\n 533:\t\n 534:\t\tif (e-\u003etype \u003e= MAX_IPTUN_ENCAP_OPS)\n 535:\t\t\treturn -EINVAL;\n 536:\t\n 537:\t\trcu_read_lock();\n 538:\t\tops = rcu_dereference(iptun_encaps[e-\u003etype]);\n 539:\t\tif (likely(ops \u0026\u0026 ops-\u003eencap_hlen))\n 540:\t\t\thlen = ops-\u003eencap_hlen(e);\n 541:\t\trcu_read_unlock();\n 542:\t\n 543:\t\treturn hlen;\n 544:\t}\n 545:\t\n 546:\tstatic inline int ip_tunnel_encap(struct sk_buff *skb,\n 547:\t\t\t\t\t struct ip_tunnel_encap *e,\n 548:\t\t\t\t\t u8 *protocol, struct flowi4 *fl4)\n 549:\t{\n 550:\t\tconst struct ip_tunnel_encap_ops *ops;\n 551:\t\tint ret = -EINVAL;\n 552:\t\n 553:\t\tif (e-\u003etype == TUNNEL_ENCAP_NONE)\n 554:\t\t\treturn 0;\n 555:\t\n 556:\t\tif (e-\u003etype \u003e= MAX_IPTUN_ENCAP_OPS)\n 557:\t\t\treturn -EINVAL;\n 558:\t\n 559:\t\trcu_read_lock();\n"
} |
| 27/3 | 2026/09/06 05:01 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 12375 output: 282 thoughts: 981 Thoughts: **Analysis of Tunnel Encapsulation Patch** Okay, let's break down this patch. My immediate thought is to delve into the code changes, specifically focusing on potential risks and vulnerabilities, as an expert in the field would. First, I see the core changes revolve around `tnl_update_pmtu` and `ip_tunnel_xmit`. The addition of `encap_hlen` as an argument to `tnl_update_pmtu` is key. It signals a shift in how the encapsulation header length is handled, directly impacting packet size calculations, and therefore, PMTU determination. The change to `pkt_size` calculation (`skb->len + encap_hlen - tunnel_hlen`) is obviously where this impact lies, and needs to be accounted for. The important thing is that `ip_tunnel_xmit` now *snapshots* the encapsulation configuration into a local variable, `ipencap`, using `data_race(tunnel->encap)`. This *must* be about addressing a potential race condition and ensuring a consistent view of the encapsulation settings during the transmission process. This encapsulation occurs right before `iptunnel_xmit`, after a check for available headroom. Now, I'm thinking about potential vulnerabilities. We *must* verify if any uninitialized memory read or information leak risk exists here. `ipencap` is populated via a struct assignment from `tunnel->encap`, this is a good sign. `encap_hlen` is derived from `ipencap` via a dedicated function, `ip_encap_hlen()`, which, on its own, seems safe. I need to make sure `tnl_update_pmtu` is also not reading any uninitialized data, which it shouldn't, since it's only receiving the `encap_hlen` int. No data is copied to user space, and importantly, the `pkt_size` calculation is solely used for PMTU/ICMP calculations and fragments, so there shouldn't be any issues there. We need to dive deeper. Is there any struct padding info-leaks, uninitialized stack/heap reads, or branching on uninitialized data? `ipencap` is initialized via struct assignment *before* being used in `ip_encap_hlen()` and `ip_tunnel_encap()`. `encap_hlen` is initialized before use. All branches rely on initialized variables. No data goes to userspace. This seems robust. What bugs are fixed or potentially introduced? This looks like a race condition fix by snapshotting the encapsulation parameters. It's moving the encapsulation *after* headroom expansion, which is smart, to prevent writing out of bounds, and the PMTU calculation is corrected by accounting for the encapsulation header length. These are good changes. Finally, does this patch warrant KMSAN? KMSAN is for detecting uninitialized memory access and info leaks to userspace. Because all variables are initialized and no data is copied to user space, there is no need for KMSAN. Let's do a final check to confirm that conclusion: 1. No kernel structures are sent to userspace where padding might not be fully initialized. 2. No conditional logic depends on uninitialized data. 3. No allocation of complex data structures with uninitialized fields. 4. Bounds checks and lengths are done safely. Therefore, `NeedsKMSAN = false`. It's a solid patch, addressing real concurrency, buffer-handling, and logic concerns without introducing KMSAN-relevant issues. |
| 28/3 | 2026/09/06 05:02 | tool | set-results |
0mArgs:{
"KMSANReasoning": "The patch addresses data races and PMTU/headroom calculations in IPv4 tunnel transmission (ip_tunnel_xmit and tnl_update_pmtu). Specifically:\n1. It snapshots `tunnel-\u003eencap` into a stack variable `ipencap` using `data_race()` to prevent concurrent modification by `ipgre_changelink()`.\n2. It accounts for `encap_hlen` in `tnl_update_pmtu` and defers calling `ip_tunnel_encap()` until after skb headroom is expanded with `skb_cow_head()`.\n\nRegarding sanitizers:\n- Memory safety bugs related to buffer headroom, skb bounds, and use-after-free are covered by KASAN.\n- Concurrency issues and data races are targeted by KCSAN/LOCKDEP.\n- The local variable `ipencap` is fully initialized via structure assignment before any read, `encap_hlen` is an integer initialized with the return value of `ip_encap_hlen()`, and no kernel memory is copied to user space. There is no risk of uninitialized memory reads or information leaks.\n\nTherefore, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
}Results: {
"KMSANReasoning": "The patch addresses data races and PMTU/headroom calculations in IPv4 tunnel transmission (ip_tunnel_xmit and tnl_update_pmtu). Specifically:\n1. It snapshots `tunnel-\u003eencap` into a stack variable `ipencap` using `data_race()` to prevent concurrent modification by `ipgre_changelink()`.\n2. It accounts for `encap_hlen` in `tnl_update_pmtu` and defers calling `ip_tunnel_encap()` until after skb headroom is expanded with `skb_cow_head()`.\n\nRegarding sanitizers:\n- Memory safety bugs related to buffer headroom, skb bounds, and use-after-free are covered by KASAN.\n- Concurrency issues and data races are targeted by KCSAN/LOCKDEP.\n- The local variable `ipencap` is fully initialized via structure assignment before any read, `encap_hlen` is an integer initialized with the return value of `ip_encap_hlen()`, and no kernel memory is copied to user space. There is no risk of uninitialized memory reads or information leaks.\n\nTherefore, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
} |
| Total Calls | Total Tokens | Avg Tokens | Total Duration (Seconds) | Avg Duration (Seconds) |
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| Total Calls | Total Duration (Seconds) | Avg Duration (Seconds) |
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