net/core/ptp_classifier.c

// 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);

bool ptp_msg_is_sync(struct sk_buff *skb, unsigned int type)
{
	struct ptp_header *hdr;

	hdr = ptp_parse_header(skb, type);
	if (!hdr)
		return false;

	return ptp_get_msgtype(hdr, type) == PTP_MSGTYPE_SYNC;
}
EXPORT_SYMBOL_GPL(ptp_msg_is_sync);

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));
}