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Commit 76db8087 authored by Yonghong Song's avatar Yonghong Song Committed by David S. Miller
Browse files

net: bpf: add a test for skb_segment in test_bpf module 



Without the previous commit,
"modprobe test_bpf" will have the following errors:
...
[   98.149165] ------------[ cut here ]------------
[   98.159362] kernel BUG at net/core/skbuff.c:3667!
[   98.169756] invalid opcode: 0000 [#1] SMP PTI
[   98.179370] Modules linked in:
[   98.179371]  test_bpf(+)
...
which triggers the bug the previous commit intends to fix.

The skbs are constructed to mimic what mlx5 may generate.
The packet size/header may not mimic real cases in production. But
the processing flow is similar.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 13acc94e

lib/test_bpf.c

+91 −2
Original line number Diff line number Diff line
@@ -6574,6 +6574,93 @@ static bool exclude_test(int test_id) 
	return test_id < test_range[0] || test_id > test_range[1];

}



static __init struct sk_buff *build_test_skb(void)

{

	u32 headroom = NET_SKB_PAD + NET_IP_ALIGN + ETH_HLEN;

	struct sk_buff *skb[2];

	struct page *page[2];

	int i, data_size = 8;



	for (i = 0; i < 2; i++) {

		page[i] = alloc_page(GFP_KERNEL);

		if (!page[i]) {

			if (i == 0)

				goto err_page0;

			else

				goto err_page1;

		}



		/* this will set skb[i]->head_frag */

		skb[i] = dev_alloc_skb(headroom + data_size);

		if (!skb[i]) {

			if (i == 0)

				goto err_skb0;

			else

				goto err_skb1;

		}



		skb_reserve(skb[i], headroom);

		skb_put(skb[i], data_size);

		skb[i]->protocol = htons(ETH_P_IP);

		skb_reset_network_header(skb[i]);

		skb_set_mac_header(skb[i], -ETH_HLEN);



		skb_add_rx_frag(skb[i], 0, page[i], 0, 64, 64);

		// skb_headlen(skb[i]): 8, skb[i]->head_frag = 1

	}



	/* setup shinfo */

	skb_shinfo(skb[0])->gso_size = 1448;

	skb_shinfo(skb[0])->gso_type = SKB_GSO_TCPV4;

	skb_shinfo(skb[0])->gso_type |= SKB_GSO_DODGY;

	skb_shinfo(skb[0])->gso_segs = 0;

	skb_shinfo(skb[0])->frag_list = skb[1];



	/* adjust skb[0]'s len */

	skb[0]->len += skb[1]->len;

	skb[0]->data_len += skb[1]->data_len;

	skb[0]->truesize += skb[1]->truesize;



	return skb[0];



err_skb1:

	__free_page(page[1]);

err_page1:

	kfree_skb(skb[0]);

err_skb0:

	__free_page(page[0]);

err_page0:

	return NULL;

}



static __init int test_skb_segment(void)

{

	netdev_features_t features;

	struct sk_buff *skb, *segs;

	int ret = -1;



	features = NETIF_F_SG | NETIF_F_GSO_PARTIAL | NETIF_F_IP_CSUM |

		   NETIF_F_IPV6_CSUM;

	features |= NETIF_F_RXCSUM;

	skb = build_test_skb();

	if (!skb) {

		pr_info("%s: failed to build_test_skb", __func__);

		goto done;

	}



	segs = skb_segment(skb, features);

	if (segs) {

		kfree_skb_list(segs);

		ret = 0;

		pr_info("%s: success in skb_segment!", __func__);

	} else {

		pr_info("%s: failed in skb_segment!", __func__);

	}

	kfree_skb(skb);

done:

	return ret;

}



static __init int test_bpf(void)

{

	int i, err_cnt = 0, pass_cnt = 0;
@@ -6632,9 +6719,11 @@ static int __init test_bpf_init(void) 
		return ret;



	ret = test_bpf();



	destroy_bpf_tests();

	if (ret)

		return ret;



	return test_skb_segment();

}



static void __exit test_bpf_exit(void)