b6fc0956ac
Currently GTP packets are dropped if the next extension field is set to non-zero value, but this are valid GTP packets. TS 29.281 provides a longer header format, which is defined as struct gtp1_header_long. Such long header format is used if any of the S, PN, E flags is set. This long header is 4 bytes longer than struct gtp1_header, plus variable length (optional) extension headers. The next extension header field is zero is no extension header is provided. The extension header is composed of a length field which includes total number of 4 byte words including the extension header itself (1 byte), payload (variable length) and next type (1 byte). The extension header size and its payload is aligned to 4 bytes. A GTP packet might come with a chain extensions headers, which makes it slightly cumbersome to parse because the extension next header field comes at the end of the extension header, and there is a need to check if this field becomes zero to stop the extension header parser. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
87 lines
1.5 KiB
C
87 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _GTP_H_
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#define _GTP_H_
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#include <linux/netdevice.h>
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#include <linux/types.h>
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#include <net/rtnetlink.h>
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/* General GTP protocol related definitions. */
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#define GTP0_PORT 3386
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#define GTP1U_PORT 2152
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/* GTP messages types */
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#define GTP_ECHO_REQ 1 /* Echo Request */
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#define GTP_ECHO_RSP 2 /* Echo Response */
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#define GTP_TPDU 255
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#define GTPIE_RECOVERY 14
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struct gtp0_header { /* According to GSM TS 09.60. */
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__u8 flags;
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__u8 type;
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__be16 length;
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__be16 seq;
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__be16 flow;
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__u8 number;
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__u8 spare[3];
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__be64 tid;
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} __attribute__ ((packed));
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struct gtp1_header { /* According to 3GPP TS 29.060. */
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__u8 flags;
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__u8 type;
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__be16 length;
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__be32 tid;
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} __attribute__ ((packed));
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struct gtp1_header_long { /* According to 3GPP TS 29.060. */
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__u8 flags;
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__u8 type;
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__be16 length;
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__be32 tid;
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__be16 seq;
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__u8 npdu;
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__u8 next;
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} __packed;
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/* GTP Information Element */
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struct gtp_ie {
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__u8 tag;
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__u8 val;
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} __packed;
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struct gtp0_packet {
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struct gtp0_header gtp0_h;
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struct gtp_ie ie;
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} __packed;
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struct gtp1u_packet {
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struct gtp1_header_long gtp1u_h;
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struct gtp_ie ie;
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} __packed;
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struct gtp_pdu_session_info { /* According to 3GPP TS 38.415. */
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u8 pdu_type;
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u8 qfi;
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};
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static inline bool netif_is_gtp(const struct net_device *dev)
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{
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return dev->rtnl_link_ops &&
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!strcmp(dev->rtnl_link_ops->kind, "gtp");
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}
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#define GTP1_F_NPDU 0x01
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#define GTP1_F_SEQ 0x02
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#define GTP1_F_EXTHDR 0x04
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#define GTP1_F_MASK 0x07
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struct gtp_ext_hdr {
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__u8 len;
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__u8 data[];
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};
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#endif
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