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David Lebrundavem330
David Lebrun
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davem330
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ipv6: sr: add core files for SR HMAC support
This patch adds the necessary functions to compute and check the HMAC signature of an SR-enabled packet. Two HMAC algorithms are supported: hmac(sha1) and hmac(sha256). In order to avoid dynamic memory allocation for each HMAC computation, a per-cpu ring buffer is allocated for this purpose. A new per-interface sysctl called seg6_require_hmac is added, allowing a user-defined policy for processing HMAC-signed SR-enabled packets. A value of -1 means that the HMAC field will always be ignored. A value of 0 means that if an HMAC field is present, its validity will be enforced (the packet is dropped is the signature is incorrect). Finally, a value of 1 means that any SR-enabled packet that does not contain an HMAC signature or whose signature is incorrect will be dropped. Signed-off-by: David Lebrun <david.lebrun@uclouvain.be> Signed-off-by: David S. Miller <davem@davemloft.net>
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‎include/linux/ipv6.h‎

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@@ -65,6 +65,9 @@ struct ipv6_devconf {
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__s32 use_oif_addrs_only;
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__s32 keep_addr_on_down;
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__s32 seg6_enabled;
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#ifdef CONFIG_IPV6_SEG6_HMAC
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__s32 seg6_require_hmac;
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#endif
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struct ctl_table_header *sysctl_header;
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};

‎include/linux/seg6_hmac.h‎

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@@ -0,0 +1,6 @@
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#ifndef _LINUX_SEG6_HMAC_H
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#define _LINUX_SEG6_HMAC_H
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#include <uapi/linux/seg6_hmac.h>
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#endif

‎include/net/seg6.h‎

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@@ -18,6 +18,7 @@
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#include <linux/ipv6.h>
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#include <net/lwtunnel.h>
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#include <linux/seg6.h>
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#include <linux/rhashtable.h>
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static inline void update_csum_diff4(struct sk_buff *skb, __be32 from,
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__be32 to)
@@ -41,6 +42,9 @@ static inline void update_csum_diff16(struct sk_buff *skb, __be32 *from,
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struct seg6_pernet_data {
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struct mutex lock;
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struct in6_addr __rcu *tun_src;
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#ifdef CONFIG_IPV6_SEG6_HMAC
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struct rhashtable hmac_infos;
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#endif
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};
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static inline struct seg6_pernet_data *seg6_pernet(struct net *net)

‎include/net/seg6_hmac.h‎

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@@ -0,0 +1,62 @@
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/*
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* SR-IPv6 implementation
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*
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* Author:
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* David Lebrun <david.lebrun@uclouvain.be>
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*
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _NET_SEG6_HMAC_H
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#define _NET_SEG6_HMAC_H
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#include <net/flow.h>
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#include <net/ip6_fib.h>
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#include <net/sock.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/route.h>
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#include <net/seg6.h>
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#include <linux/seg6_hmac.h>
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#include <linux/rhashtable.h>
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#define SEG6_HMAC_MAX_DIGESTSIZE 160
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#define SEG6_HMAC_RING_SIZE 256
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struct seg6_hmac_info {
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struct rhash_head node;
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struct rcu_head rcu;
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u32 hmackeyid;
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char secret[SEG6_HMAC_SECRET_LEN];
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u8 slen;
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u8 alg_id;
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};
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struct seg6_hmac_algo {
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u8 alg_id;
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char name[64];
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struct crypto_shash * __percpu *tfms;
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struct shash_desc * __percpu *shashs;
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};
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extern int seg6_hmac_compute(struct seg6_hmac_info *hinfo,
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struct ipv6_sr_hdr *hdr, struct in6_addr *saddr,
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u8 *output);
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extern struct seg6_hmac_info *seg6_hmac_info_lookup(struct net *net, u32 key);
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extern int seg6_hmac_info_add(struct net *net, u32 key,
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struct seg6_hmac_info *hinfo);
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extern int seg6_hmac_info_del(struct net *net, u32 key);
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extern int seg6_push_hmac(struct net *net, struct in6_addr *saddr,
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struct ipv6_sr_hdr *srh);
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extern bool seg6_hmac_validate_skb(struct sk_buff *skb);
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extern int seg6_hmac_init(void);
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extern void seg6_hmac_exit(void);
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extern int seg6_hmac_net_init(struct net *net);
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extern void seg6_hmac_net_exit(struct net *net);
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#endif

‎include/uapi/linux/ipv6.h‎

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@@ -180,6 +180,7 @@ enum {
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DEVCONF_KEEP_ADDR_ON_DOWN,
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DEVCONF_RTR_SOLICIT_MAX_INTERVAL,
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DEVCONF_SEG6_ENABLED,
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DEVCONF_SEG6_REQUIRE_HMAC,
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DEVCONF_MAX
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};
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‎include/uapi/linux/seg6_hmac.h‎

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#ifndef _UAPI_LINUX_SEG6_HMAC_H
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#define _UAPI_LINUX_SEG6_HMAC_H
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#include <linux/seg6.h>
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#define SEG6_HMAC_SECRET_LEN 64
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#define SEG6_HMAC_FIELD_LEN 32
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struct sr6_tlv_hmac {
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struct sr6_tlv tlvhdr;
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__u16 reserved;
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__be32 hmackeyid;
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__u8 hmac[SEG6_HMAC_FIELD_LEN];
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};
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enum {
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SEG6_HMAC_ALGO_SHA1 = 1,
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SEG6_HMAC_ALGO_SHA256 = 2,
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};
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#endif

‎net/ipv6/Kconfig‎

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@@ -301,4 +301,16 @@ config IPV6_SEG6_INLINE
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If unsure, say N.
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config IPV6_SEG6_HMAC
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bool "IPv6: Segment Routing HMAC support"
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depends on IPV6
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select CRYPTO_HMAC
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select CRYPTO_SHA1
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select CRYPTO_SHA256
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---help---
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Support for HMAC signature generation and verification
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of SR-enabled packets.
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If unsure, say N.
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endif # IPV6

‎net/ipv6/Makefile‎

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@@ -44,6 +44,7 @@ obj-$(CONFIG_IPV6_SIT) += sit.o
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obj-$(CONFIG_IPV6_TUNNEL) += ip6_tunnel.o
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obj-$(CONFIG_IPV6_GRE) += ip6_gre.o
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obj-$(CONFIG_IPV6_FOU) += fou6.o
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obj-$(CONFIG_IPV6_SEG6_HMAC) += seg6_hmac.o
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obj-y += addrconf_core.o exthdrs_core.o ip6_checksum.o ip6_icmp.o
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obj-$(CONFIG_INET) += output_core.o protocol.o $(ipv6-offload)

‎net/ipv6/addrconf.c‎

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@@ -239,6 +239,9 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
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.ignore_routes_with_linkdown = 0,
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.keep_addr_on_down = 0,
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.seg6_enabled = 0,
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#ifdef CONFIG_IPV6_SEG6_HMAC
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.seg6_require_hmac = 0,
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#endif
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};
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static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
@@ -286,6 +289,9 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
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.ignore_routes_with_linkdown = 0,
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.keep_addr_on_down = 0,
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.seg6_enabled = 0,
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#ifdef CONFIG_IPV6_SEG6_HMAC
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.seg6_require_hmac = 0,
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#endif
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};
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/* Check if a valid qdisc is available */
@@ -4947,6 +4953,9 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
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array[DEVCONF_DROP_UNSOLICITED_NA] = cnf->drop_unsolicited_na;
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array[DEVCONF_KEEP_ADDR_ON_DOWN] = cnf->keep_addr_on_down;
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array[DEVCONF_SEG6_ENABLED] = cnf->seg6_enabled;
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#ifdef CONFIG_IPV6_SEG6_HMAC
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array[DEVCONF_SEG6_REQUIRE_HMAC] = cnf->seg6_require_hmac;
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#endif
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}
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static inline size_t inet6_ifla6_size(void)
@@ -6045,6 +6054,15 @@ static const struct ctl_table addrconf_sysctl[] = {
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.mode = 0644,
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.proc_handler = proc_dointvec,
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},
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#ifdef CONFIG_IPV6_SEG6_HMAC
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{
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.procname = "seg6_require_hmac",
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.data = &ipv6_devconf.seg6_require_hmac,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec,
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},
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#endif
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{
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/* sentinel */
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}

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