/
icmp6.h
479 lines (408 loc) · 15.6 KB
/
icmp6.h
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/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
/* Copyright Authors of Cilium */
#if !defined(__LIB_ICMP6__) && defined(ENABLE_IPV6)
#define __LIB_ICMP6__
#include <linux/icmpv6.h>
#include <linux/in.h>
#include "common.h"
#include "eth.h"
#include "drop.h"
#include "eps.h"
#define ICMP6_TYPE_OFFSET offsetof(struct icmp6hdr, icmp6_type)
#define ICMP6_CSUM_OFFSET (sizeof(struct ipv6hdr) + offsetof(struct icmp6hdr, icmp6_cksum))
#define ICMP6_ND_TARGET_OFFSET (sizeof(struct ipv6hdr) + sizeof(struct icmp6hdr))
#define ICMP6_ND_OPTS (sizeof(struct ipv6hdr) + sizeof(struct icmp6hdr) + sizeof(struct in6_addr))
#define ICMP6_UNREACH_MSG_TYPE 1
#define ICMP6_PARAM_ERR_MSG_TYPE 4
#define ICMP6_ECHO_REQUEST_MSG_TYPE 128
#define ICMP6_ECHO_REPLY_MSG_TYPE 129
#define ICMP6_MULT_LIST_QUERY_TYPE 130
#define ICMP6_NS_MSG_TYPE 135
#define ICMP6_NA_MSG_TYPE 136
#define ICMP6_RR_MSG_TYPE 138
#define ICMP6_INV_NS_MSG_TYPE 141
#define ICMP6_MULT_LIST_REPORT_V2_TYPE 143
#define ICMP6_SEND_NS_MSG_TYPE 148
#define ICMP6_SEND_NA_MSG_TYPE 149
#define ICMP6_MULT_RA_MSG_TYPE 151
#define ICMP6_MULT_RT_MSG_TYPE 153
#define SKIP_HOST_FIREWALL -2
/* If no specific action is specified, drop unknown neighbour solicitation
* messages.
*/
#ifndef ACTION_UNKNOWN_ICMP6_NS
#define ACTION_UNKNOWN_ICMP6_NS DROP_UNKNOWN_TARGET
#endif
static __always_inline int icmp6_load_type(struct __ctx_buff *ctx, int l4_off, __u8 *type)
{
return ctx_load_bytes(ctx, l4_off + ICMP6_TYPE_OFFSET, type, sizeof(*type));
}
static __always_inline int icmp6_send_reply(struct __ctx_buff *ctx, int nh_off)
{
union macaddr smac, dmac = NODE_MAC;
const int csum_off = nh_off + ICMP6_CSUM_OFFSET;
union v6addr sip, dip, router_ip;
__be32 sum;
if (ipv6_load_saddr(ctx, nh_off, &sip) < 0 ||
ipv6_load_daddr(ctx, nh_off, &dip) < 0)
return DROP_INVALID;
BPF_V6(router_ip, ROUTER_IP);
/* ctx->saddr = ctx->daddr */
if (ipv6_store_saddr(ctx, router_ip.addr, nh_off) < 0)
return DROP_WRITE_ERROR;
/* ctx->daddr = ctx->saddr */
if (ipv6_store_daddr(ctx, sip.addr, nh_off) < 0)
return DROP_WRITE_ERROR;
/* fixup checksums */
sum = csum_diff(sip.addr, 16, router_ip.addr, 16, 0);
if (l4_csum_replace(ctx, csum_off, 0, sum, BPF_F_PSEUDO_HDR) < 0)
return DROP_CSUM_L4;
sum = csum_diff(dip.addr, 16, sip.addr, 16, 0);
if (l4_csum_replace(ctx, csum_off, 0, sum, BPF_F_PSEUDO_HDR) < 0)
return DROP_CSUM_L4;
/* dmac = smac, smac = dmac */
if (eth_load_saddr(ctx, smac.addr, 0) < 0)
return DROP_INVALID;
if (eth_store_daddr(ctx, smac.addr, 0) < 0 ||
eth_store_saddr(ctx, dmac.addr, 0) < 0)
return DROP_WRITE_ERROR;
cilium_dbg_capture(ctx, DBG_CAPTURE_DELIVERY, ctx_get_ifindex(ctx));
return redirect_self(ctx);
}
/*
* send_icmp6_ndisc_adv
* @ctx: socket buffer
* @nh_off: offset to the IPv6 header
* @mac: device mac address
* @to_router: ndisc is sent to router, otherwise ndisc is sent to an endpoint.
*
* Send an ICMPv6 nadv reply in return to an ICMPv6 ndisc.
*/
static __always_inline int
send_icmp6_ndisc_adv(struct __ctx_buff *ctx, int nh_off,
const union macaddr *mac, bool to_router)
{
struct icmp6hdr icmp6hdr __align_stack_8 = {}, icmp6hdr_old __align_stack_8;
__u8 opts[8], opts_old[8];
const int csum_off = nh_off + ICMP6_CSUM_OFFSET;
__be32 sum;
if (ctx_load_bytes(ctx, nh_off + sizeof(struct ipv6hdr), &icmp6hdr_old,
sizeof(icmp6hdr_old)) < 0)
return DROP_INVALID;
/* fill icmp6hdr */
icmp6hdr.icmp6_type = 136;
icmp6hdr.icmp6_code = 0;
icmp6hdr.icmp6_cksum = icmp6hdr_old.icmp6_cksum;
icmp6hdr.icmp6_dataun.un_data32[0] = 0;
if (to_router) {
icmp6hdr.icmp6_router = 1;
icmp6hdr.icmp6_solicited = 1;
icmp6hdr.icmp6_override = 0;
} else {
icmp6hdr.icmp6_router = 0;
icmp6hdr.icmp6_solicited = 1;
icmp6hdr.icmp6_override = 1;
}
if (ctx_store_bytes(ctx, nh_off + sizeof(struct ipv6hdr), &icmp6hdr,
sizeof(icmp6hdr), 0) < 0)
return DROP_WRITE_ERROR;
/* fixup checksums */
sum = csum_diff(&icmp6hdr_old, sizeof(icmp6hdr_old),
&icmp6hdr, sizeof(icmp6hdr), 0);
if (l4_csum_replace(ctx, csum_off, 0, sum, BPF_F_PSEUDO_HDR) < 0)
return DROP_CSUM_L4;
/* get old options */
if (ctx_load_bytes(ctx, nh_off + ICMP6_ND_OPTS, opts_old, sizeof(opts_old)) < 0)
return DROP_INVALID;
opts[0] = 2;
opts[1] = 1;
opts[2] = mac->addr[0];
opts[3] = mac->addr[1];
opts[4] = mac->addr[2];
opts[5] = mac->addr[3];
opts[6] = mac->addr[4];
opts[7] = mac->addr[5];
/* store ND_OPT_TARGET_LL_ADDR option */
if (ctx_store_bytes(ctx, nh_off + ICMP6_ND_OPTS, opts, sizeof(opts), 0) < 0)
return DROP_WRITE_ERROR;
/* fixup checksum */
sum = csum_diff(opts_old, sizeof(opts_old), opts, sizeof(opts), 0);
if (l4_csum_replace(ctx, csum_off, 0, sum, BPF_F_PSEUDO_HDR) < 0)
return DROP_CSUM_L4;
return icmp6_send_reply(ctx, nh_off);
}
static __always_inline __be32 compute_icmp6_csum(char data[80], __u16 payload_len,
struct ipv6hdr *ipv6hdr)
{
__be32 sum;
/* compute checksum with new payload length */
sum = csum_diff(NULL, 0, data, payload_len, 0);
sum = ipv6_pseudohdr_checksum(ipv6hdr, IPPROTO_ICMPV6, payload_len,
sum);
return sum;
}
static __always_inline int __icmp6_send_time_exceeded(struct __ctx_buff *ctx,
int nh_off)
{
/* FIXME: Fix code below to not require this init */
char data[80] = {};
struct icmp6hdr *icmp6hoplim;
struct ipv6hdr *ipv6hdr;
char *upper; /* icmp6 or tcp or udp */
const int csum_off = nh_off + ICMP6_CSUM_OFFSET;
__be32 sum = 0;
__u16 payload_len = 0; /* FIXME: Uninit of this causes verifier bug */
__u8 icmp6_nexthdr = IPPROTO_ICMPV6;
int trimlen;
/* initialize pointers to offsets in data */
icmp6hoplim = (struct icmp6hdr *)data;
ipv6hdr = (struct ipv6hdr *)(data + 8);
upper = (data + 48);
/* fill icmp6hdr */
icmp6hoplim->icmp6_type = 3;
icmp6hoplim->icmp6_code = 0;
icmp6hoplim->icmp6_cksum = 0;
icmp6hoplim->icmp6_dataun.un_data32[0] = 0;
cilium_dbg(ctx, DBG_ICMP6_TIME_EXCEEDED, 0, 0);
/* read original v6 hdr into offset 8 */
if (ctx_load_bytes(ctx, nh_off, ipv6hdr, sizeof(*ipv6hdr)) < 0)
return DROP_INVALID;
if (ipv6_store_nexthdr(ctx, &icmp6_nexthdr, nh_off) < 0)
return DROP_WRITE_ERROR;
/* read original v6 payload into offset 48 */
switch (ipv6hdr->nexthdr) {
case IPPROTO_ICMPV6:
#ifdef ENABLE_SCTP
case IPPROTO_SCTP:
#endif /* ENABLE_SCTP */
case IPPROTO_UDP:
if (ctx_load_bytes(ctx, nh_off + sizeof(struct ipv6hdr),
upper, 8) < 0)
return DROP_INVALID;
sum = compute_icmp6_csum(data, 56, ipv6hdr);
payload_len = bpf_htons(56);
trimlen = 56 - bpf_ntohs(ipv6hdr->payload_len);
if (ctx_change_tail(ctx, ctx_full_len(ctx) + trimlen, 0) < 0)
return DROP_WRITE_ERROR;
/* trim or expand buffer and copy data buffer after ipv6 header */
if (ctx_store_bytes(ctx, nh_off + sizeof(struct ipv6hdr),
data, 56, 0) < 0)
return DROP_WRITE_ERROR;
if (ipv6_store_paylen(ctx, nh_off, &payload_len) < 0)
return DROP_WRITE_ERROR;
break;
/* copy header without options */
case IPPROTO_TCP:
if (ctx_load_bytes(ctx, nh_off + sizeof(struct ipv6hdr),
upper, 20) < 0)
return DROP_INVALID;
sum = compute_icmp6_csum(data, 68, ipv6hdr);
payload_len = bpf_htons(68);
/* trim or expand buffer and copy data buffer after ipv6 header */
trimlen = 68 - bpf_ntohs(ipv6hdr->payload_len);
if (ctx_change_tail(ctx, ctx_full_len(ctx) + trimlen, 0) < 0)
return DROP_WRITE_ERROR;
if (ctx_store_bytes(ctx, nh_off + sizeof(struct ipv6hdr),
data, 68, 0) < 0)
return DROP_WRITE_ERROR;
if (ipv6_store_paylen(ctx, nh_off, &payload_len) < 0)
return DROP_WRITE_ERROR;
break;
default:
return DROP_UNKNOWN_L4;
}
if (l4_csum_replace(ctx, csum_off, 0, sum, BPF_F_PSEUDO_HDR) < 0)
return DROP_CSUM_L4;
return icmp6_send_reply(ctx, nh_off);
}
#ifndef SKIP_ICMPV6_HOPLIMIT_HANDLING
__section_tail(CILIUM_MAP_CALLS, CILIUM_CALL_SEND_ICMP6_TIME_EXCEEDED)
int tail_icmp6_send_time_exceeded(struct __ctx_buff *ctx __maybe_unused)
{
int ret, nh_off = ctx_load_and_clear_meta(ctx, 0);
enum metric_dir direction = (enum metric_dir)ctx_load_meta(ctx, 1);
ret = __icmp6_send_time_exceeded(ctx, nh_off);
if (IS_ERR(ret))
return send_drop_notify_error(ctx, 0, ret, CTX_ACT_DROP,
direction);
return ret;
}
/*
* icmp6_send_time_exceeded
* @ctx: socket buffer
* @nh_off: offset to the IPv6 header
* @direction: direction of packet (can be ingress or egress)
* Send a ICMPv6 time exceeded in response to an IPv6 frame.
*
* NOTE: This is terminal function and will cause the BPF program to exit
*/
static __always_inline int icmp6_send_time_exceeded(struct __ctx_buff *ctx,
int nh_off, enum metric_dir direction)
{
ctx_store_meta(ctx, 0, nh_off);
ctx_store_meta(ctx, 1, direction);
return tail_call_internal(ctx, CILIUM_CALL_SEND_ICMP6_TIME_EXCEEDED, NULL);
}
#endif
static __always_inline int __icmp6_handle_ns(struct __ctx_buff *ctx, int nh_off)
{
union v6addr target, router;
struct endpoint_info *ep;
union macaddr router_mac = NODE_MAC;
if (ctx_load_bytes(ctx, nh_off + ICMP6_ND_TARGET_OFFSET, target.addr,
sizeof(((struct ipv6hdr *)NULL)->saddr)) < 0)
return DROP_INVALID;
cilium_dbg(ctx, DBG_ICMP6_NS, target.p3, target.p4);
BPF_V6(router, ROUTER_IP);
if (ipv6_addr_equals(&target, &router)) {
return send_icmp6_ndisc_adv(ctx, nh_off, &router_mac, true);
}
ep = __lookup_ip6_endpoint(&target);
if (ep) {
if (ep->flags & ENDPOINT_F_HOST) {
/* Target must be a node_ip, because of ENDPOINT_F_HOST flag
* and target != router_ip.
*
* We pass these packets to stack to make sure:
*
* 1. The response NA has node IP as source address instead of
* router IP, to address https://github.com/cilium/cilium/issues/14509.
*
* 2. Kernel stack can record a neighbor entry for the
* source IP, to avoid bpf_fib_lookup failure as mentioned at
* https://github.com/cilium/cilium/pull/30837#issuecomment-1960897445.
*/
return CTX_ACT_OK;
}
return send_icmp6_ndisc_adv(ctx, nh_off, &router_mac, false);
}
/* Unknown target address, drop */
return ACTION_UNKNOWN_ICMP6_NS;
}
#ifndef SKIP_ICMPV6_NS_HANDLING
__section_tail(CILIUM_MAP_CALLS, CILIUM_CALL_HANDLE_ICMP6_NS)
int tail_icmp6_handle_ns(struct __ctx_buff *ctx)
{
int ret, nh_off = ctx_load_and_clear_meta(ctx, 0);
enum metric_dir direction = (enum metric_dir)ctx_load_meta(ctx, 1);
ret = __icmp6_handle_ns(ctx, nh_off);
if (IS_ERR(ret))
return send_drop_notify_error(ctx, 0, ret, CTX_ACT_DROP, direction);
return ret;
}
#endif
/*
* icmp6_handle_ns
* @ctx: socket buffer
* @nh_off: offset to the IPv6 header
* @direction: direction of packet(ingress or egress)
* @ext_err: extended error value
*
* Respond to ICMPv6 Neighbour Solicitation
*
* NOTE: This is terminal function and will cause the BPF program to exit
*/
static __always_inline int icmp6_handle_ns(struct __ctx_buff *ctx, int nh_off,
enum metric_dir direction,
__s8 *ext_err)
{
ctx_store_meta(ctx, 0, nh_off);
ctx_store_meta(ctx, 1, direction);
return tail_call_internal(ctx, CILIUM_CALL_HANDLE_ICMP6_NS, ext_err);
}
static __always_inline bool
is_icmp6_ndp(struct __ctx_buff *ctx, const struct ipv6hdr *ip6, int nh_off)
{
__u8 type;
if (icmp6_load_type(ctx, nh_off + sizeof(struct ipv6hdr), &type) < 0)
return false;
return ip6->nexthdr == IPPROTO_ICMPV6 &&
(type == ICMP6_NS_MSG_TYPE || type == ICMP6_NA_MSG_TYPE);
}
static __always_inline int icmp6_ndp_handle(struct __ctx_buff *ctx, int nh_off,
enum metric_dir direction,
__s8 *ext_err)
{
__u8 type;
if (icmp6_load_type(ctx, nh_off + sizeof(struct ipv6hdr), &type) < 0)
return DROP_INVALID;
cilium_dbg(ctx, DBG_ICMP6_HANDLE, type, 0);
if (type == ICMP6_NS_MSG_TYPE)
return icmp6_handle_ns(ctx, nh_off, direction, ext_err);
/* All branching above will have issued a tail call, all
* remaining traffic is subject to forwarding to containers.
*/
return 0;
}
static __always_inline int
icmp6_host_handle(struct __ctx_buff *ctx, int l4_off, __s8 *ext_err, bool handle_ns)
{
__u8 type;
if (icmp6_load_type(ctx, l4_off, &type) < 0)
return DROP_INVALID;
if (type == ICMP6_NS_MSG_TYPE && handle_ns)
return icmp6_handle_ns(ctx, ETH_HLEN, METRIC_INGRESS, ext_err);
#ifdef ENABLE_HOST_FIREWALL
/* When the host firewall is enabled, we drop and allow ICMPv6 messages
* according to RFC4890, except for echo request and reply messages which
* are handled by host policies and can be dropped.
* | ICMPv6 Message | Action | Type |
* |---------------------------------|-----------------|------|
* | ICMPv6-unreach | CTX_ACT_OK | 1 |
* | ICMPv6-too-big | CTX_ACT_OK | 2 |
* | ICMPv6-timed | CTX_ACT_OK | 3 |
* | ICMPv6-parameter | CTX_ACT_OK | 4 |
* | ICMPv6-err-private-exp-100 | CTX_ACT_DROP | 100 |
* | ICMPv6-err-private-exp-101 | CTX_ACT_DROP | 101 |
* | ICMPv6-err-expansion | CTX_ACT_DROP | 127 |
* | ICMPv6-echo-message | Firewall | 128 |
* | ICMPv6-echo-reply | Firewall | 129 |
* | ICMPv6-mult-list-query | CTX_ACT_OK | 130 |
* | ICMPv6-mult-list-report | CTX_ACT_OK | 131 |
* | ICMPv6-mult-list-done | CTX_ACT_OK | 132 |
* | ICMPv6-router-solici | CTX_ACT_OK | 133 |
* | ICMPv6-router-advert | CTX_ACT_OK | 134 |
* | ICMPv6-neighbor-solicit | icmp6_handle_ns | 135 |
* | ICMPv6-neighbor-advert | CTX_ACT_OK | 136 |
* | ICMPv6-redirect-message | CTX_ACT_DROP | 137 |
* | ICMPv6-router-renumber | CTX_ACT_OK | 138 |
* | ICMPv6-node-info-query | CTX_ACT_DROP | 139 |
* | ICMPv6-node-info-response | CTX_ACT_DROP | 140 |
* | ICMPv6-inv-neighbor-solicit | CTX_ACT_OK | 141 |
* | ICMPv6-inv-neighbor-advert | CTX_ACT_OK | 142 |
* | ICMPv6-mult-list-report-v2 | CTX_ACT_OK | 143 |
* | ICMPv6-home-agent-disco-request | CTX_ACT_DROP | 144 |
* | ICMPv6-home-agent-disco-reply | CTX_ACT_DROP | 145 |
* | ICMPv6-mobile-solicit | CTX_ACT_DROP | 146 |
* | ICMPv6-mobile-advert | CTX_ACT_DROP | 147 |
* | ICMPv6-send-solicit | CTX_ACT_OK | 148 |
* | ICMPv6-send-advert | CTX_ACT_OK | 149 |
* | ICMPv6-mobile-exp | CTX_ACT_DROP | 150 |
* | ICMPv6-mult-router-advert | CTX_ACT_OK | 151 |
* | ICMPv6-mult-router-solicit | CTX_ACT_OK | 152 |
* | ICMPv6-mult-router-term | CTX_ACT_OK | 153 |
* | ICMPv6-FMIPv6 | CTX_ACT_DROP | 154 |
* | ICMPv6-rpl-control | CTX_ACT_DROP | 155 |
* | ICMPv6-info-private-exp-200 | CTX_ACT_DROP | 200 |
* | ICMPv6-info-private-exp-201 | CTX_ACT_DROP | 201 |
* | ICMPv6-info-expansion | CTX_ACT_DROP | 255 |
* | ICMPv6-unallocated | CTX_ACT_DROP | |
* | ICMPv6-unassigned | CTX_ACT_DROP | |
*/
if (type == ICMP6_NS_MSG_TYPE)
return CTX_ACT_OK;
if (type == ICMP6_ECHO_REQUEST_MSG_TYPE || type == ICMP6_ECHO_REPLY_MSG_TYPE)
/* Decision is deferred to the host policies. */
return CTX_ACT_OK;
if ((ICMP6_UNREACH_MSG_TYPE <= type && type <= ICMP6_PARAM_ERR_MSG_TYPE) ||
(ICMP6_MULT_LIST_QUERY_TYPE <= type && type <= ICMP6_NA_MSG_TYPE) ||
(ICMP6_INV_NS_MSG_TYPE <= type && type <= ICMP6_MULT_LIST_REPORT_V2_TYPE) ||
(ICMP6_SEND_NS_MSG_TYPE <= type && type <= ICMP6_SEND_NA_MSG_TYPE) ||
(ICMP6_MULT_RA_MSG_TYPE <= type && type <= ICMP6_MULT_RT_MSG_TYPE))
return SKIP_HOST_FIREWALL;
return DROP_FORBIDDEN_ICMP6;
#else
return CTX_ACT_OK;
#endif /* ENABLE_HOST_FIREWALL */
}
#endif