net/core/ptp_classifier.c

Source file repositories/reference/linux-study-clean/net/core/ptp_classifier.c

File Facts

System: Linux kernel
Corpus path: net/core/ptp_classifier.c
Extension: .c
Size: 7871 bytes
Lines: 229
Domain: Networking Core
Bucket: Sockets, Protocols, Packet Path, And Network Policy
Inferred role: Networking Core: exported/initcall integration point
Status: integration implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.
Exports symbols or registers init work; inspect boot/module ordering and who consumes the exported contract.
Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

linux/skbuff.h
linux/filter.h
linux/ptp_classify.h

Detected Declarations

function ptp_classify_raw
function ptp_msg_is_sync
function ptp_classifier_init
export ptp_classify_raw
export ptp_parse_header
export ptp_msg_is_sync

Annotated Snippet

// 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

Annotation

Immediate include surface: `linux/skbuff.h`, `linux/filter.h`, `linux/ptp_classify.h`.
Detected declarations: `function ptp_classify_raw`, `function ptp_msg_is_sync`, `function ptp_classifier_init`, `export ptp_classify_raw`, `export ptp_parse_header`, `export ptp_msg_is_sync`.
Atlas domain: Networking Core / Sockets, Protocols, Packet Path, And Network Policy.
Implementation status: integration implementation candidate.

Implementation Notes

This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.