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ptp_classifier.c
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// SPDX-License-Identifier: GPL-2.0-only
/* PTP classifier
*/
/* The below program is the bpf_asm (tools/net/) representation of
* the opcode array in the ptp_filter structure.
*
* For convenience, this can easily be altered and reviewed with
* bpf_asm and bpf_dbg, e.g. `./bpf_asm -c prog` where prog is a
* simple file containing the below program:
*
* ldh [12] ; load ethertype
*
* ; PTP over UDP over IPv4 over Ethernet
* test_ipv4:
* jneq #0x800, test_ipv6 ; ETH_P_IP ?
* ldb [23] ; load proto
* jneq #17, drop_ipv4 ; IPPROTO_UDP ?
* ldh [20] ; load frag offset field
* jset #0x1fff, drop_ipv4 ; don't allow fragments
* ldxb 4*([14]&0xf) ; load IP header len
* ldh [x + 16] ; load UDP dst port
* jneq #319, drop_ipv4 ; is port PTP_EV_PORT ?
* ldh [x + 22] ; load payload
* and #0xf ; mask PTP_CLASS_VMASK
* or #0x10 ; PTP_CLASS_IPV4
* ret a ; return PTP class
* drop_ipv4: ret #0x0 ; PTP_CLASS_NONE
*
* ; PTP over UDP over IPv6 over Ethernet
* test_ipv6:
* jneq #0x86dd, test_8021q ; ETH_P_IPV6 ?
* ldb [20] ; load proto
* jneq #17, drop_ipv6 ; IPPROTO_UDP ?
* ldh [56] ; load UDP dst port
* jneq #319, drop_ipv6 ; is port PTP_EV_PORT ?
* ldh [62] ; load payload
* and #0xf ; mask PTP_CLASS_VMASK
* or #0x20 ; PTP_CLASS_IPV6
* ret a ; return PTP class
* drop_ipv6: ret #0x0 ; PTP_CLASS_NONE
*
* ; PTP over 802.1Q over Ethernet
* test_8021q:
* jneq #0x8100, test_ieee1588 ; ETH_P_8021Q ?
* ldh [16] ; load inner type
* jneq #0x88f7, test_8021q_ipv4 ; ETH_P_1588 ?
* ldb [18] ; load payload
* and #0x8 ; as we don't have ports here, test
* jneq #0x0, drop_ieee1588 ; for PTP_GEN_BIT and drop these
* ldh [18] ; reload payload
* and #0xf ; mask PTP_CLASS_VMASK
* or #0xc0 ; PTP_CLASS_VLAN|PTP_CLASS_L2
* ret a ; return PTP class
*
* ; PTP over UDP over IPv4 over 802.1Q over Ethernet
* test_8021q_ipv4:
* jneq #0x800, test_8021q_ipv6 ; ETH_P_IP ?
* ldb [27] ; load proto
* jneq #17, drop_8021q_ipv4 ; IPPROTO_UDP ?
* ldh [24] ; load frag offset field
* jset #0x1fff, drop_8021q_ipv4; don't allow fragments
* ldxb 4*([18]&0xf) ; load IP header len
* ldh [x + 20] ; load UDP dst port
* jneq #319, drop_8021q_ipv4 ; is port PTP_EV_PORT ?
* ldh [x + 26] ; load payload
* and #0xf ; mask PTP_CLASS_VMASK
* or #0x90 ; PTP_CLASS_VLAN|PTP_CLASS_IPV4
* ret a ; return PTP class
* drop_8021q_ipv4: ret #0x0 ; PTP_CLASS_NONE
*
* ; PTP over UDP over IPv6 over 802.1Q over Ethernet
* test_8021q_ipv6:
* jneq #0x86dd, drop_8021q_ipv6 ; ETH_P_IPV6 ?
* ldb [24] ; load proto
* jneq #17, drop_8021q_ipv6 ; IPPROTO_UDP ?
* ldh [60] ; load UDP dst port
* jneq #319, drop_8021q_ipv6 ; is port PTP_EV_PORT ?
* ldh [66] ; load payload
* and #0xf ; mask PTP_CLASS_VMASK
* or #0xa0 ; PTP_CLASS_VLAN|PTP_CLASS_IPV6
* ret a ; return PTP class
* drop_8021q_ipv6: ret #0x0 ; PTP_CLASS_NONE
*
* ; PTP over Ethernet
* test_ieee1588:
* jneq #0x88f7, drop_ieee1588 ; ETH_P_1588 ?
* ldb [14] ; load payload
* and #0x8 ; as we don't have ports here, test
* jneq #0x0, drop_ieee1588 ; for PTP_GEN_BIT and drop these
* ldh [14] ; reload payload
* and #0xf ; mask PTP_CLASS_VMASK
* or #0x40 ; PTP_CLASS_L2
* ret a ; return PTP class
* drop_ieee1588: ret #0x0 ; PTP_CLASS_NONE
*/
#include <linux/skbuff.h>
#include <linux/filter.h>
#include <linux/ptp_classify.h>
static struct bpf_prog *ptp_insns __read_mostly;
unsigned int ptp_classify_raw(const struct sk_buff *skb)
{
return BPF_PROG_RUN(ptp_insns, skb);
}
EXPORT_SYMBOL_GPL(ptp_classify_raw);
struct ptp_header *ptp_parse_header(struct sk_buff *skb, unsigned int type)
{
u8 *ptr = skb_mac_header(skb);
if (type & PTP_CLASS_VLAN)
ptr += VLAN_HLEN;
switch (type & PTP_CLASS_PMASK) {
case PTP_CLASS_IPV4:
ptr += IPV4_HLEN(ptr) + UDP_HLEN;
break;
case PTP_CLASS_IPV6:
ptr += IP6_HLEN + UDP_HLEN;
break;
case PTP_CLASS_L2:
break;
default:
return NULL;
}
ptr += ETH_HLEN;
/* Ensure that the entire header is present in this packet. */
if (ptr + sizeof(struct ptp_header) > skb->data + skb->len)
return NULL;
return (struct ptp_header *)ptr;
}
EXPORT_SYMBOL_GPL(ptp_parse_header);
void __init ptp_classifier_init(void)
{
static struct sock_filter ptp_filter[] __initdata = {
{ 0x28, 0, 0, 0x0000000c },
{ 0x15, 0, 12, 0x00000800 },
{ 0x30, 0, 0, 0x00000017 },
{ 0x15, 0, 9, 0x00000011 },
{ 0x28, 0, 0, 0x00000014 },
{ 0x45, 7, 0, 0x00001fff },
{ 0xb1, 0, 0, 0x0000000e },
{ 0x48, 0, 0, 0x00000010 },
{ 0x15, 0, 4, 0x0000013f },
{ 0x48, 0, 0, 0x00000016 },
{ 0x54, 0, 0, 0x0000000f },
{ 0x44, 0, 0, 0x00000010 },
{ 0x16, 0, 0, 0x00000000 },
{ 0x06, 0, 0, 0x00000000 },
{ 0x15, 0, 9, 0x000086dd },
{ 0x30, 0, 0, 0x00000014 },
{ 0x15, 0, 6, 0x00000011 },
{ 0x28, 0, 0, 0x00000038 },
{ 0x15, 0, 4, 0x0000013f },
{ 0x28, 0, 0, 0x0000003e },
{ 0x54, 0, 0, 0x0000000f },
{ 0x44, 0, 0, 0x00000020 },
{ 0x16, 0, 0, 0x00000000 },
{ 0x06, 0, 0, 0x00000000 },
{ 0x15, 0, 32, 0x00008100 },
{ 0x28, 0, 0, 0x00000010 },
{ 0x15, 0, 7, 0x000088f7 },
{ 0x30, 0, 0, 0x00000012 },
{ 0x54, 0, 0, 0x00000008 },
{ 0x15, 0, 35, 0x00000000 },
{ 0x28, 0, 0, 0x00000012 },
{ 0x54, 0, 0, 0x0000000f },
{ 0x44, 0, 0, 0x000000c0 },
{ 0x16, 0, 0, 0x00000000 },
{ 0x15, 0, 12, 0x00000800 },
{ 0x30, 0, 0, 0x0000001b },
{ 0x15, 0, 9, 0x00000011 },
{ 0x28, 0, 0, 0x00000018 },
{ 0x45, 7, 0, 0x00001fff },
{ 0xb1, 0, 0, 0x00000012 },
{ 0x48, 0, 0, 0x00000014 },
{ 0x15, 0, 4, 0x0000013f },
{ 0x48, 0, 0, 0x0000001a },
{ 0x54, 0, 0, 0x0000000f },
{ 0x44, 0, 0, 0x00000090 },
{ 0x16, 0, 0, 0x00000000 },
{ 0x06, 0, 0, 0x00000000 },
{ 0x15, 0, 8, 0x000086dd },
{ 0x30, 0, 0, 0x00000018 },
{ 0x15, 0, 6, 0x00000011 },
{ 0x28, 0, 0, 0x0000003c },
{ 0x15, 0, 4, 0x0000013f },
{ 0x28, 0, 0, 0x00000042 },
{ 0x54, 0, 0, 0x0000000f },
{ 0x44, 0, 0, 0x000000a0 },
{ 0x16, 0, 0, 0x00000000 },
{ 0x06, 0, 0, 0x00000000 },
{ 0x15, 0, 7, 0x000088f7 },
{ 0x30, 0, 0, 0x0000000e },
{ 0x54, 0, 0, 0x00000008 },
{ 0x15, 0, 4, 0x00000000 },
{ 0x28, 0, 0, 0x0000000e },
{ 0x54, 0, 0, 0x0000000f },
{ 0x44, 0, 0, 0x00000040 },
{ 0x16, 0, 0, 0x00000000 },
{ 0x06, 0, 0, 0x00000000 },
};
struct sock_fprog_kern ptp_prog;
ptp_prog.len = ARRAY_SIZE(ptp_filter);
ptp_prog.filter = ptp_filter;
BUG_ON(bpf_prog_create(&ptp_insns, &ptp_prog));
}