Commit 6c02568f authored by Max Tottenham's avatar Max Tottenham Committed by David S. Miller
Browse files

net/sched: act_pedit: Parse L3 Header for L4 offset 



Instead of relying on skb->transport_header being set correctly, opt
instead to parse the L3 header length out of the L3 headers for both
IPv4/IPv6 when the Extended Layer Op for tcp/udp is used. This fixes a
bug if GRO is disabled, when GRO is disabled skb->transport_header is
set by __netif_receive_skb_core() to point to the L3 header, it's later
fixed by the upper protocol layers, but act_pedit will receive the SKB
before the fixups are completed. The existing behavior causes the
following to edit the L3 header if GRO is disabled instead of the UDP
header:

    tc filter add dev eth0 ingress protocol ip flower ip_proto udp \
 dst_ip 192.168.1.3 action pedit ex munge udp set dport 18053

Also re-introduce a rate-limited warning if we were unable to extract
the header offset when using the 'ex' interface.

Fixes: 71d0ed70 ("net/act_pedit: Support using offset relative to
the conventional network headers")
Signed-off-by: default avatarMax Tottenham <mtottenh@akamai.com>
Reviewed-by: default avatarJosh Hunt <johunt@akamai.com>
Reported-by: default avatarkernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202305261541.N165u9TZ-lkp@intel.com/


Reviewed-by: default avatarPedro Tammela <pctammela@mojatatu.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 86319919

net/sched/act_pedit.c

+43 −5
Original line number Diff line number Diff line
@@ -13,7 +13,10 @@ 
#include <linux/rtnetlink.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/ip.h>

#include <linux/ipv6.h>

#include <linux/slab.h>

#include <net/ipv6.h>

#include <net/netlink.h>

#include <net/pkt_sched.h>

#include <linux/tc_act/tc_pedit.h>
@@ -327,28 +330,58 @@ static bool offset_valid(struct sk_buff *skb, int offset) 
	return true;

}



static void pedit_skb_hdr_offset(struct sk_buff *skb,

static int pedit_l4_skb_offset(struct sk_buff *skb, int *hoffset, const int header_type)

{

	const int noff = skb_network_offset(skb);

	int ret = -EINVAL;

	struct iphdr _iph;



	switch (skb->protocol) {

	case htons(ETH_P_IP): {

		const struct iphdr *iph = skb_header_pointer(skb, noff, sizeof(_iph), &_iph);



		if (!iph)

			goto out;

		*hoffset = noff + iph->ihl * 4;

		ret = 0;

		break;

	}

	case htons(ETH_P_IPV6):

		ret = ipv6_find_hdr(skb, hoffset, header_type, NULL, NULL) == header_type ? 0 : -EINVAL;

		break;

	}

out:

	return ret;

}



static int pedit_skb_hdr_offset(struct sk_buff *skb,

				 enum pedit_header_type htype, int *hoffset)

{

	int ret = -EINVAL;

	/* 'htype' is validated in the netlink parsing */

	switch (htype) {

	case TCA_PEDIT_KEY_EX_HDR_TYPE_ETH:

		if (skb_mac_header_was_set(skb))

		if (skb_mac_header_was_set(skb)) {

			*hoffset = skb_mac_offset(skb);

			ret = 0;

		}

		break;

	case TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK:

	case TCA_PEDIT_KEY_EX_HDR_TYPE_IP4:

	case TCA_PEDIT_KEY_EX_HDR_TYPE_IP6:

		*hoffset = skb_network_offset(skb);

		ret = 0;

		break;

	case TCA_PEDIT_KEY_EX_HDR_TYPE_TCP:

		ret = pedit_l4_skb_offset(skb, hoffset, IPPROTO_TCP);

		break;

	case TCA_PEDIT_KEY_EX_HDR_TYPE_UDP:

		if (skb_transport_header_was_set(skb))

			*hoffset = skb_transport_offset(skb);

		ret = pedit_l4_skb_offset(skb, hoffset, IPPROTO_UDP);

		break;

	default:

		break;

	}

	return ret;

}



TC_INDIRECT_SCOPE int tcf_pedit_act(struct sk_buff *skb,
@@ -384,6 +417,7 @@ TC_INDIRECT_SCOPE int tcf_pedit_act(struct sk_buff *skb, 
		int hoffset = 0;

		u32 *ptr, hdata;

		u32 val;

		int rc;



		if (tkey_ex) {

			htype = tkey_ex->htype;
@@ -392,7 +426,11 @@ TC_INDIRECT_SCOPE int tcf_pedit_act(struct sk_buff *skb, 
			tkey_ex++;

		}



		pedit_skb_hdr_offset(skb, htype, &hoffset);

		rc = pedit_skb_hdr_offset(skb, htype, &hoffset);

		if (rc) {

			pr_info_ratelimited("tc action pedit unable to extract header offset for header type (0x%x)\n", htype);

			goto bad;

		}



		if (tkey->offmask) {

			u8 *d, _d;