291 lines
6.9 KiB
C
291 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/* Copyright (c) 2020 Jesper Dangaard Brouer */
|
|
|
|
#include <linux/bpf.h>
|
|
#include <bpf/bpf_helpers.h>
|
|
#include <linux/if_ether.h>
|
|
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
|
|
char _license[] SEC("license") = "GPL";
|
|
|
|
/* Userspace will update with MTU it can see on device */
|
|
volatile const int GLOBAL_USER_MTU;
|
|
volatile const __u32 GLOBAL_USER_IFINDEX;
|
|
|
|
/* BPF-prog will update these with MTU values it can see */
|
|
__u32 global_bpf_mtu_xdp = 0;
|
|
__u32 global_bpf_mtu_tc = 0;
|
|
|
|
SEC("xdp")
|
|
int xdp_use_helper_basic(struct xdp_md *ctx)
|
|
{
|
|
__u32 mtu_len = 0;
|
|
|
|
if (bpf_check_mtu(ctx, 0, &mtu_len, 0, 0))
|
|
return XDP_ABORTED;
|
|
|
|
return XDP_PASS;
|
|
}
|
|
|
|
SEC("xdp")
|
|
int xdp_use_helper(struct xdp_md *ctx)
|
|
{
|
|
int retval = XDP_PASS; /* Expected retval on successful test */
|
|
__u32 mtu_len = 0;
|
|
__u32 ifindex = 0;
|
|
int delta = 0;
|
|
|
|
/* When ifindex is zero, save net_device lookup and use ctx netdev */
|
|
if (GLOBAL_USER_IFINDEX > 0)
|
|
ifindex = GLOBAL_USER_IFINDEX;
|
|
|
|
if (bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0)) {
|
|
/* mtu_len is also valid when check fail */
|
|
retval = XDP_ABORTED;
|
|
goto out;
|
|
}
|
|
|
|
if (mtu_len != GLOBAL_USER_MTU)
|
|
retval = XDP_DROP;
|
|
|
|
out:
|
|
global_bpf_mtu_xdp = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("xdp")
|
|
int xdp_exceed_mtu(struct xdp_md *ctx)
|
|
{
|
|
void *data_end = (void *)(long)ctx->data_end;
|
|
void *data = (void *)(long)ctx->data;
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
__u32 data_len = data_end - data;
|
|
int retval = XDP_ABORTED; /* Fail */
|
|
__u32 mtu_len = 0;
|
|
int delta;
|
|
int err;
|
|
|
|
/* Exceed MTU with 1 via delta adjust */
|
|
delta = GLOBAL_USER_MTU - (data_len - ETH_HLEN) + 1;
|
|
|
|
err = bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0);
|
|
if (err) {
|
|
retval = XDP_PASS; /* Success in exceeding MTU check */
|
|
if (err != BPF_MTU_CHK_RET_FRAG_NEEDED)
|
|
retval = XDP_DROP;
|
|
}
|
|
|
|
global_bpf_mtu_xdp = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("xdp")
|
|
int xdp_minus_delta(struct xdp_md *ctx)
|
|
{
|
|
int retval = XDP_PASS; /* Expected retval on successful test */
|
|
void *data_end = (void *)(long)ctx->data_end;
|
|
void *data = (void *)(long)ctx->data;
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
__u32 data_len = data_end - data;
|
|
__u32 mtu_len = 0;
|
|
int delta;
|
|
|
|
/* Borderline test case: Minus delta exceeding packet length allowed */
|
|
delta = -((data_len - ETH_HLEN) + 1);
|
|
|
|
/* Minus length (adjusted via delta) still pass MTU check, other helpers
|
|
* are responsible for catching this, when doing actual size adjust
|
|
*/
|
|
if (bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0))
|
|
retval = XDP_ABORTED;
|
|
|
|
global_bpf_mtu_xdp = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("xdp")
|
|
int xdp_input_len(struct xdp_md *ctx)
|
|
{
|
|
int retval = XDP_PASS; /* Expected retval on successful test */
|
|
void *data_end = (void *)(long)ctx->data_end;
|
|
void *data = (void *)(long)ctx->data;
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
__u32 data_len = data_end - data;
|
|
|
|
/* API allow user give length to check as input via mtu_len param,
|
|
* resulting MTU value is still output in mtu_len param after call.
|
|
*
|
|
* Input len is L3, like MTU and iph->tot_len.
|
|
* Remember XDP data_len is L2.
|
|
*/
|
|
__u32 mtu_len = data_len - ETH_HLEN;
|
|
|
|
if (bpf_check_mtu(ctx, ifindex, &mtu_len, 0, 0))
|
|
retval = XDP_ABORTED;
|
|
|
|
global_bpf_mtu_xdp = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("xdp")
|
|
int xdp_input_len_exceed(struct xdp_md *ctx)
|
|
{
|
|
int retval = XDP_ABORTED; /* Fail */
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
int err;
|
|
|
|
/* API allow user give length to check as input via mtu_len param,
|
|
* resulting MTU value is still output in mtu_len param after call.
|
|
*
|
|
* Input length value is L3 size like MTU.
|
|
*/
|
|
__u32 mtu_len = GLOBAL_USER_MTU;
|
|
|
|
mtu_len += 1; /* Exceed with 1 */
|
|
|
|
err = bpf_check_mtu(ctx, ifindex, &mtu_len, 0, 0);
|
|
if (err == BPF_MTU_CHK_RET_FRAG_NEEDED)
|
|
retval = XDP_PASS ; /* Success in exceeding MTU check */
|
|
|
|
global_bpf_mtu_xdp = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("tc")
|
|
int tc_use_helper(struct __sk_buff *ctx)
|
|
{
|
|
int retval = BPF_OK; /* Expected retval on successful test */
|
|
__u32 mtu_len = 0;
|
|
int delta = 0;
|
|
|
|
if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
|
|
retval = BPF_DROP;
|
|
goto out;
|
|
}
|
|
|
|
if (mtu_len != GLOBAL_USER_MTU)
|
|
retval = BPF_REDIRECT;
|
|
out:
|
|
global_bpf_mtu_tc = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("tc")
|
|
int tc_exceed_mtu(struct __sk_buff *ctx)
|
|
{
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
int retval = BPF_DROP; /* Fail */
|
|
__u32 skb_len = ctx->len;
|
|
__u32 mtu_len = 0;
|
|
int delta;
|
|
int err;
|
|
|
|
/* Exceed MTU with 1 via delta adjust */
|
|
delta = GLOBAL_USER_MTU - (skb_len - ETH_HLEN) + 1;
|
|
|
|
err = bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0);
|
|
if (err) {
|
|
retval = BPF_OK; /* Success in exceeding MTU check */
|
|
if (err != BPF_MTU_CHK_RET_FRAG_NEEDED)
|
|
retval = BPF_DROP;
|
|
}
|
|
|
|
global_bpf_mtu_tc = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("tc")
|
|
int tc_exceed_mtu_da(struct __sk_buff *ctx)
|
|
{
|
|
/* SKB Direct-Access variant */
|
|
void *data_end = (void *)(long)ctx->data_end;
|
|
void *data = (void *)(long)ctx->data;
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
__u32 data_len = data_end - data;
|
|
int retval = BPF_DROP; /* Fail */
|
|
__u32 mtu_len = 0;
|
|
int delta;
|
|
int err;
|
|
|
|
/* Exceed MTU with 1 via delta adjust */
|
|
delta = GLOBAL_USER_MTU - (data_len - ETH_HLEN) + 1;
|
|
|
|
err = bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0);
|
|
if (err) {
|
|
retval = BPF_OK; /* Success in exceeding MTU check */
|
|
if (err != BPF_MTU_CHK_RET_FRAG_NEEDED)
|
|
retval = BPF_DROP;
|
|
}
|
|
|
|
global_bpf_mtu_tc = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("tc")
|
|
int tc_minus_delta(struct __sk_buff *ctx)
|
|
{
|
|
int retval = BPF_OK; /* Expected retval on successful test */
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
__u32 skb_len = ctx->len;
|
|
__u32 mtu_len = 0;
|
|
int delta;
|
|
|
|
/* Borderline test case: Minus delta exceeding packet length allowed */
|
|
delta = -((skb_len - ETH_HLEN) + 1);
|
|
|
|
/* Minus length (adjusted via delta) still pass MTU check, other helpers
|
|
* are responsible for catching this, when doing actual size adjust
|
|
*/
|
|
if (bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0))
|
|
retval = BPF_DROP;
|
|
|
|
global_bpf_mtu_xdp = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("tc")
|
|
int tc_input_len(struct __sk_buff *ctx)
|
|
{
|
|
int retval = BPF_OK; /* Expected retval on successful test */
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
|
|
/* API allow user give length to check as input via mtu_len param,
|
|
* resulting MTU value is still output in mtu_len param after call.
|
|
*
|
|
* Input length value is L3 size.
|
|
*/
|
|
__u32 mtu_len = GLOBAL_USER_MTU;
|
|
|
|
if (bpf_check_mtu(ctx, ifindex, &mtu_len, 0, 0))
|
|
retval = BPF_DROP;
|
|
|
|
global_bpf_mtu_xdp = mtu_len;
|
|
return retval;
|
|
}
|
|
|
|
SEC("tc")
|
|
int tc_input_len_exceed(struct __sk_buff *ctx)
|
|
{
|
|
int retval = BPF_DROP; /* Fail */
|
|
__u32 ifindex = GLOBAL_USER_IFINDEX;
|
|
int err;
|
|
|
|
/* API allow user give length to check as input via mtu_len param,
|
|
* resulting MTU value is still output in mtu_len param after call.
|
|
*
|
|
* Input length value is L3 size like MTU.
|
|
*/
|
|
__u32 mtu_len = GLOBAL_USER_MTU;
|
|
|
|
mtu_len += 1; /* Exceed with 1 */
|
|
|
|
err = bpf_check_mtu(ctx, ifindex, &mtu_len, 0, 0);
|
|
if (err == BPF_MTU_CHK_RET_FRAG_NEEDED)
|
|
retval = BPF_OK; /* Success in exceeding MTU check */
|
|
|
|
global_bpf_mtu_xdp = mtu_len;
|
|
return retval;
|
|
}
|