Re: [ 157/184] inet: add RCU protection to inet->opt

From: Ben Hutchings
Date: Fri Jun 07 2013 - 02:12:29 EST

On Tue, 2013-06-04 at 19:24 +0200, Willy Tarreau wrote:
> 2.6.32-longterm review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
>
> commit f6d8bd051c391c1c0458a30b2a7abcd939329259 upstream.
>
> We lack proper synchronization to manipulate inet->opt ip_options
>
> Problem is ip_make_skb() calls ip_setup_cork() and
> ip_setup_cork() possibly makes a copy of ipc->opt (struct ip_options),
> without any protection against another thread manipulating inet->opt.
>
> Another thread can change inet->opt pointer and free old one under us.
>
> Use RCU to protect inet->opt (changed to inet->inet_opt).
>
> Instead of handling atomic refcounts, just copy ip_options when
> necessary, to avoid cache line dirtying.
>
> We cant insert an rcu_head in struct ip_options since its included in
> skb->cb[], so this patch is large because I had to introduce a new
> ip_options_rcu structure.
>
> Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> [dannf/bwh: backported to Debian's 2.6.32]

Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>

> Signed-off-by: Willy Tarreau <w@xxxxxx>
> ---
> include/net/inet_sock.h | 14 +++--
> include/net/ip.h | 11 ++--
> net/dccp/ipv4.c | 15 +++---
> net/dccp/ipv6.c | 2 +-
> net/ipv4/af_inet.c | 16 ++++--
> net/ipv4/cipso_ipv4.c | 113 ++++++++++++++++++++++------------------
> net/ipv4/icmp.c | 23 ++++----
> net/ipv4/inet_connection_sock.c | 8 +--
> net/ipv4/ip_options.c | 38 +++++++-------
> net/ipv4/ip_output.c | 50 +++++++++---------
> net/ipv4/ip_sockglue.c | 33 ++++++++----
> net/ipv4/raw.c | 19 +++++--
> net/ipv4/syncookies.c | 4 +-
> net/ipv4/tcp_ipv4.c | 33 +++++++-----
> net/ipv4/udp.c | 21 ++++++--
> net/ipv6/tcp_ipv6.c | 2 +-
> 16 files changed, 235 insertions(+), 167 deletions(-)
>
> diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
> index 47004f3..cf65e77 100644
> --- a/include/net/inet_sock.h
> +++ b/include/net/inet_sock.h
> @@ -56,7 +56,15 @@ struct ip_options {
> unsigned char __data[0];
> };
>
> -#define optlength(opt) (sizeof(struct ip_options) + opt->optlen)
> +struct ip_options_rcu {
> + struct rcu_head rcu;
> + struct ip_options opt;
> +};
> +
> +struct ip_options_data {
> + struct ip_options_rcu opt;
> + char data[40];
> +};
>
> struct inet_request_sock {
> struct request_sock req;
> @@ -77,7 +85,7 @@ struct inet_request_sock {
> acked : 1,
> no_srccheck: 1;
> kmemcheck_bitfield_end(flags);
> - struct ip_options *opt;
> + struct ip_options_rcu *opt;
> };
>
> static inline struct inet_request_sock *inet_rsk(const struct request_sock *sk)
> @@ -122,7 +130,7 @@ struct inet_sock {
> __be32 saddr;
> __s16 uc_ttl;
> __u16 cmsg_flags;
> - struct ip_options *opt;
> + struct ip_options_rcu *inet_opt;
> __be16 sport;
> __u16 id;
> __u8 tos;
> diff --git a/include/net/ip.h b/include/net/ip.h
> index 69db943..a7d4675 100644
> --- a/include/net/ip.h
> +++ b/include/net/ip.h
> @@ -54,7 +54,7 @@ struct ipcm_cookie
> {
> __be32 addr;
> int oif;
> - struct ip_options *opt;
> + struct ip_options_rcu *opt;
> union skb_shared_tx shtx;
> };
>
> @@ -92,7 +92,7 @@ extern int igmp_mc_proc_init(void);
>
> extern int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
> __be32 saddr, __be32 daddr,
> - struct ip_options *opt);
> + struct ip_options_rcu *opt);
> extern int ip_rcv(struct sk_buff *skb, struct net_device *dev,
> struct packet_type *pt, struct net_device *orig_dev);
> extern int ip_local_deliver(struct sk_buff *skb);
> @@ -362,14 +362,15 @@ extern int ip_forward(struct sk_buff *skb);
> * Functions provided by ip_options.c
> */
>
> -extern void ip_options_build(struct sk_buff *skb, struct ip_options *opt, __be32 daddr, struct rtable *rt, int is_frag);
> +extern void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
> + __be32 daddr, struct rtable *rt, int is_frag);
> extern int ip_options_echo(struct ip_options *dopt, struct sk_buff *skb);
> extern void ip_options_fragment(struct sk_buff *skb);
> extern int ip_options_compile(struct net *net,
> struct ip_options *opt, struct sk_buff *skb);
> -extern int ip_options_get(struct net *net, struct ip_options **optp,
> +extern int ip_options_get(struct net *net, struct ip_options_rcu **optp,
> unsigned char *data, int optlen);
> -extern int ip_options_get_from_user(struct net *net, struct ip_options **optp,
> +extern int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
> unsigned char __user *data, int optlen);
> extern void ip_options_undo(struct ip_options * opt);
> extern void ip_forward_options(struct sk_buff *skb);
> diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
> index d14c0a3..cef3656 100644
> --- a/net/dccp/ipv4.c
> +++ b/net/dccp/ipv4.c
> @@ -47,6 +47,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> __be32 daddr, nexthop;
> int tmp;
> int err;
> + struct ip_options_rcu *inet_opt;
>
> dp->dccps_role = DCCP_ROLE_CLIENT;
>
> @@ -57,10 +58,12 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> return -EAFNOSUPPORT;
>
> nexthop = daddr = usin->sin_addr.s_addr;
> - if (inet->opt != NULL && inet->opt->srr) {
> +
> + inet_opt = inet->inet_opt;
> + if (inet_opt != NULL && inet_opt->opt.srr) {
> if (daddr == 0)
> return -EINVAL;
> - nexthop = inet->opt->faddr;
> + nexthop = inet_opt->opt.faddr;
> }
>
> tmp = ip_route_connect(&rt, nexthop, inet->saddr,
> @@ -75,7 +78,7 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> return -ENETUNREACH;
> }
>
> - if (inet->opt == NULL || !inet->opt->srr)
> + if (inet_opt == NULL || !inet_opt->opt.srr)
> daddr = rt->rt_dst;
>
> if (inet->saddr == 0)
> @@ -86,8 +89,8 @@ int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> inet->daddr = daddr;
>
> inet_csk(sk)->icsk_ext_hdr_len = 0;
> - if (inet->opt != NULL)
> - inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
> + if (inet_opt)
> + inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
> /*
> * Socket identity is still unknown (sport may be zero).
> * However we set state to DCCP_REQUESTING and not releasing socket
> @@ -397,7 +400,7 @@ struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
> newinet->daddr = ireq->rmt_addr;
> newinet->rcv_saddr = ireq->loc_addr;
> newinet->saddr = ireq->loc_addr;
> - newinet->opt = ireq->opt;
> + newinet->inet_opt = ireq->opt;
> ireq->opt = NULL;
> newinet->mc_index = inet_iif(skb);
> newinet->mc_ttl = ip_hdr(skb)->ttl;
> diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
> index 9ed1962..2f11de7 100644
> --- a/net/dccp/ipv6.c
> +++ b/net/dccp/ipv6.c
> @@ -600,7 +600,7 @@ static struct sock *dccp_v6_request_recv_sock(struct sock *sk,
>
> First: no IPv4 options.
> */
> - newinet->opt = NULL;
> + newinet->inet_opt = NULL;
>
> /* Clone RX bits */
> newnp->rxopt.all = np->rxopt.all;
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index a289878..d1992a4 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -152,7 +152,7 @@ void inet_sock_destruct(struct sock *sk)
> WARN_ON(sk->sk_wmem_queued);
> WARN_ON(sk->sk_forward_alloc);
>
> - kfree(inet->opt);
> + kfree(inet->inet_opt);
> dst_release(sk->sk_dst_cache);
> sk_refcnt_debug_dec(sk);
> }
> @@ -1065,9 +1065,11 @@ static int inet_sk_reselect_saddr(struct sock *sk)
> __be32 old_saddr = inet->saddr;
> __be32 new_saddr;
> __be32 daddr = inet->daddr;
> + struct ip_options_rcu *inet_opt;
>
> - if (inet->opt && inet->opt->srr)
> - daddr = inet->opt->faddr;
> + inet_opt = inet->inet_opt;
> + if (inet_opt && inet_opt->opt.srr)
> + daddr = inet_opt->opt.faddr;
>
> /* Query new route. */
> err = ip_route_connect(&rt, daddr, 0,
> @@ -1109,6 +1111,7 @@ int inet_sk_rebuild_header(struct sock *sk)
> struct inet_sock *inet = inet_sk(sk);
> struct rtable *rt = (struct rtable *)__sk_dst_check(sk, 0);
> __be32 daddr;
> + struct ip_options_rcu *inet_opt;
> int err;
>
> /* Route is OK, nothing to do. */
> @@ -1116,9 +1119,12 @@ int inet_sk_rebuild_header(struct sock *sk)
> return 0;
>
> /* Reroute. */
> + rcu_read_lock();
> + inet_opt = rcu_dereference(inet->inet_opt);
> daddr = inet->daddr;
> - if (inet->opt && inet->opt->srr)
> - daddr = inet->opt->faddr;
> + if (inet_opt && inet_opt->opt.srr)
> + daddr = inet_opt->opt.faddr;
> + rcu_read_unlock();
> {
> struct flowi fl = {
> .oif = sk->sk_bound_dev_if,
> diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
> index 10f8f8d..b6d06d6 100644
> --- a/net/ipv4/cipso_ipv4.c
> +++ b/net/ipv4/cipso_ipv4.c
> @@ -1860,6 +1860,11 @@ static int cipso_v4_genopt(unsigned char *buf, u32 buf_len,
> return CIPSO_V4_HDR_LEN + ret_val;
> }
>
> +static void opt_kfree_rcu(struct rcu_head *head)
> +{
> + kfree(container_of(head, struct ip_options_rcu, rcu));
> +}
> +
> /**
> * cipso_v4_sock_setattr - Add a CIPSO option to a socket
> * @sk: the socket
> @@ -1882,7 +1887,7 @@ int cipso_v4_sock_setattr(struct sock *sk,
> unsigned char *buf = NULL;
> u32 buf_len;
> u32 opt_len;
> - struct ip_options *opt = NULL;
> + struct ip_options_rcu *old, *opt = NULL;
> struct inet_sock *sk_inet;
> struct inet_connection_sock *sk_conn;
>
> @@ -1918,22 +1923,25 @@ int cipso_v4_sock_setattr(struct sock *sk,
> ret_val = -ENOMEM;
> goto socket_setattr_failure;
> }
> - memcpy(opt->__data, buf, buf_len);
> - opt->optlen = opt_len;
> - opt->cipso = sizeof(struct iphdr);
> + memcpy(opt->opt.__data, buf, buf_len);
> + opt->opt.optlen = opt_len;
> + opt->opt.cipso = sizeof(struct iphdr);
> kfree(buf);
> buf = NULL;
>
> sk_inet = inet_sk(sk);
> +
> + old = sk_inet->inet_opt;
> if (sk_inet->is_icsk) {
> sk_conn = inet_csk(sk);
> - if (sk_inet->opt)
> - sk_conn->icsk_ext_hdr_len -= sk_inet->opt->optlen;
> - sk_conn->icsk_ext_hdr_len += opt->optlen;
> + if (old)
> + sk_conn->icsk_ext_hdr_len -= old->opt.optlen;
> + sk_conn->icsk_ext_hdr_len += opt->opt.optlen;
> sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
> }
> - opt = xchg(&sk_inet->opt, opt);
> - kfree(opt);
> + rcu_assign_pointer(sk_inet->inet_opt, opt);
> + if (old)
> + call_rcu(&old->rcu, opt_kfree_rcu);
>
> return 0;
>
> @@ -1963,7 +1971,7 @@ int cipso_v4_req_setattr(struct request_sock *req,
> unsigned char *buf = NULL;
> u32 buf_len;
> u32 opt_len;
> - struct ip_options *opt = NULL;
> + struct ip_options_rcu *opt = NULL;
> struct inet_request_sock *req_inet;
>
> /* We allocate the maximum CIPSO option size here so we are probably
> @@ -1991,15 +1999,16 @@ int cipso_v4_req_setattr(struct request_sock *req,
> ret_val = -ENOMEM;
> goto req_setattr_failure;
> }
> - memcpy(opt->__data, buf, buf_len);
> - opt->optlen = opt_len;
> - opt->cipso = sizeof(struct iphdr);
> + memcpy(opt->opt.__data, buf, buf_len);
> + opt->opt.optlen = opt_len;
> + opt->opt.cipso = sizeof(struct iphdr);
> kfree(buf);
> buf = NULL;
>
> req_inet = inet_rsk(req);
> opt = xchg(&req_inet->opt, opt);
> - kfree(opt);
> + if (opt)
> + call_rcu(&opt->rcu, opt_kfree_rcu);
>
> return 0;
>
> @@ -2019,34 +2028,34 @@ req_setattr_failure:
> * values on failure.
> *
> */
> -int cipso_v4_delopt(struct ip_options **opt_ptr)
> +int cipso_v4_delopt(struct ip_options_rcu **opt_ptr)
> {
> int hdr_delta = 0;
> - struct ip_options *opt = *opt_ptr;
> + struct ip_options_rcu *opt = *opt_ptr;
>
> - if (opt->srr || opt->rr || opt->ts || opt->router_alert) {
> + if (opt->opt.srr || opt->opt.rr || opt->opt.ts || opt->opt.router_alert) {
> u8 cipso_len;
> u8 cipso_off;
> unsigned char *cipso_ptr;
> int iter;
> int optlen_new;
>
> - cipso_off = opt->cipso - sizeof(struct iphdr);
> - cipso_ptr = &opt->__data[cipso_off];
> + cipso_off = opt->opt.cipso - sizeof(struct iphdr);
> + cipso_ptr = &opt->opt.__data[cipso_off];
> cipso_len = cipso_ptr[1];
>
> - if (opt->srr > opt->cipso)
> - opt->srr -= cipso_len;
> - if (opt->rr > opt->cipso)
> - opt->rr -= cipso_len;
> - if (opt->ts > opt->cipso)
> - opt->ts -= cipso_len;
> - if (opt->router_alert > opt->cipso)
> - opt->router_alert -= cipso_len;
> - opt->cipso = 0;
> + if (opt->opt.srr > opt->opt.cipso)
> + opt->opt.srr -= cipso_len;
> + if (opt->opt.rr > opt->opt.cipso)
> + opt->opt.rr -= cipso_len;
> + if (opt->opt.ts > opt->opt.cipso)
> + opt->opt.ts -= cipso_len;
> + if (opt->opt.router_alert > opt->opt.cipso)
> + opt->opt.router_alert -= cipso_len;
> + opt->opt.cipso = 0;
>
> memmove(cipso_ptr, cipso_ptr + cipso_len,
> - opt->optlen - cipso_off - cipso_len);
> + opt->opt.optlen - cipso_off - cipso_len);
>
> /* determining the new total option length is tricky because of
> * the padding necessary, the only thing i can think to do at
> @@ -2055,21 +2064,21 @@ int cipso_v4_delopt(struct ip_options **opt_ptr)
> * from there we can determine the new total option length */
> iter = 0;
> optlen_new = 0;
> - while (iter < opt->optlen)
> - if (opt->__data[iter] != IPOPT_NOP) {
> - iter += opt->__data[iter + 1];
> + while (iter < opt->opt.optlen)
> + if (opt->opt.__data[iter] != IPOPT_NOP) {
> + iter += opt->opt.__data[iter + 1];
> optlen_new = iter;
> } else
> iter++;
> - hdr_delta = opt->optlen;
> - opt->optlen = (optlen_new + 3) & ~3;
> - hdr_delta -= opt->optlen;
> + hdr_delta = opt->opt.optlen;
> + opt->opt.optlen = (optlen_new + 3) & ~3;
> + hdr_delta -= opt->opt.optlen;
> } else {
> /* only the cipso option was present on the socket so we can
> * remove the entire option struct */
> *opt_ptr = NULL;
> - hdr_delta = opt->optlen;
> - kfree(opt);
> + hdr_delta = opt->opt.optlen;
> + call_rcu(&opt->rcu, opt_kfree_rcu);
> }
>
> return hdr_delta;
> @@ -2086,15 +2095,15 @@ int cipso_v4_delopt(struct ip_options **opt_ptr)
> void cipso_v4_sock_delattr(struct sock *sk)
> {
> int hdr_delta;
> - struct ip_options *opt;
> + struct ip_options_rcu *opt;
> struct inet_sock *sk_inet;
>
> sk_inet = inet_sk(sk);
> - opt = sk_inet->opt;
> - if (opt == NULL || opt->cipso == 0)
> + opt = sk_inet->inet_opt;
> + if (opt == NULL || opt->opt.cipso == 0)
> return;
>
> - hdr_delta = cipso_v4_delopt(&sk_inet->opt);
> + hdr_delta = cipso_v4_delopt(&sk_inet->inet_opt);
> if (sk_inet->is_icsk && hdr_delta > 0) {
> struct inet_connection_sock *sk_conn = inet_csk(sk);
> sk_conn->icsk_ext_hdr_len -= hdr_delta;
> @@ -2112,12 +2121,12 @@ void cipso_v4_sock_delattr(struct sock *sk)
> */
> void cipso_v4_req_delattr(struct request_sock *req)
> {
> - struct ip_options *opt;
> + struct ip_options_rcu *opt;
> struct inet_request_sock *req_inet;
>
> req_inet = inet_rsk(req);
> opt = req_inet->opt;
> - if (opt == NULL || opt->cipso == 0)
> + if (opt == NULL || opt->opt.cipso == 0)
> return;
>
> cipso_v4_delopt(&req_inet->opt);
> @@ -2187,14 +2196,18 @@ getattr_return:
> */
> int cipso_v4_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr)
> {
> - struct ip_options *opt;
> + struct ip_options_rcu *opt;
> + int res = -ENOMSG;
>
> - opt = inet_sk(sk)->opt;
> - if (opt == NULL || opt->cipso == 0)
> - return -ENOMSG;
> -
> - return cipso_v4_getattr(opt->__data + opt->cipso - sizeof(struct iphdr),
> - secattr);
> + rcu_read_lock();
> + opt = rcu_dereference(inet_sk(sk)->inet_opt);
> + if (opt && opt->opt.cipso)
> + res = cipso_v4_getattr(opt->opt.__data +
> + opt->opt.cipso -
> + sizeof(struct iphdr),
> + secattr);
> + rcu_read_unlock();
> + return res;
> }
>
> /**
> diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
> index 5bc13fe..859d781 100644
> --- a/net/ipv4/icmp.c
> +++ b/net/ipv4/icmp.c
> @@ -107,8 +107,7 @@ struct icmp_bxm {
> __be32 times[3];
> } data;
> int head_len;
> - struct ip_options replyopts;
> - unsigned char optbuf[40];
> + struct ip_options_data replyopts;
> };
>
> /* An array of errno for error messages from dest unreach. */
> @@ -362,7 +361,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
> struct inet_sock *inet;
> __be32 daddr;
>
> - if (ip_options_echo(&icmp_param->replyopts, skb))
> + if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
> return;
>
> sk = icmp_xmit_lock(net);
> @@ -376,10 +375,10 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
> daddr = ipc.addr = rt->rt_src;
> ipc.opt = NULL;
> ipc.shtx.flags = 0;
> - if (icmp_param->replyopts.optlen) {
> - ipc.opt = &icmp_param->replyopts;
> - if (ipc.opt->srr)
> - daddr = icmp_param->replyopts.faddr;
> + if (icmp_param->replyopts.opt.opt.optlen) {
> + ipc.opt = &icmp_param->replyopts.opt;
> + if (ipc.opt->opt.srr)
> + daddr = icmp_param->replyopts.opt.opt.faddr;
> }
> {
> struct flowi fl = { .nl_u = { .ip4_u =
> @@ -516,7 +515,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
> IPTOS_PREC_INTERNETCONTROL) :
> iph->tos;
>
> - if (ip_options_echo(&icmp_param.replyopts, skb_in))
> + if (ip_options_echo(&icmp_param.replyopts.opt.opt, skb_in))
> goto out_unlock;
>
>
> @@ -532,15 +531,15 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
> icmp_param.offset = skb_network_offset(skb_in);
> inet_sk(sk)->tos = tos;
> ipc.addr = iph->saddr;
> - ipc.opt = &icmp_param.replyopts;
> + ipc.opt = &icmp_param.replyopts.opt;
> ipc.shtx.flags = 0;
>
> {
> struct flowi fl = {
> .nl_u = {
> .ip4_u = {
> - .daddr = icmp_param.replyopts.srr ?
> - icmp_param.replyopts.faddr :
> + .daddr = icmp_param.replyopts.opt.opt.srr ?
> + icmp_param.replyopts.opt.opt.faddr :
> iph->saddr,
> .saddr = saddr,
> .tos = RT_TOS(tos)
> @@ -629,7 +628,7 @@ route_done:
> room = dst_mtu(&rt->u.dst);
> if (room > 576)
> room = 576;
> - room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
> + room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
> room -= sizeof(struct icmphdr);
>
> icmp_param.data_len = skb_in->len - icmp_param.offset;
> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
> index 537731b..a3bf986 100644
> --- a/net/ipv4/inet_connection_sock.c
> +++ b/net/ipv4/inet_connection_sock.c
> @@ -356,11 +356,11 @@ struct dst_entry *inet_csk_route_req(struct sock *sk,
> {
> struct rtable *rt;
> const struct inet_request_sock *ireq = inet_rsk(req);
> - struct ip_options *opt = inet_rsk(req)->opt;
> + struct ip_options_rcu *opt = inet_rsk(req)->opt;
> struct flowi fl = { .oif = sk->sk_bound_dev_if,
> .nl_u = { .ip4_u =
> - { .daddr = ((opt && opt->srr) ?
> - opt->faddr :
> + { .daddr = ((opt && opt->opt.srr) ?
> + opt->opt.faddr :
> ireq->rmt_addr),
> .saddr = ireq->loc_addr,
> .tos = RT_CONN_FLAGS(sk) } },
> @@ -374,7 +374,7 @@ struct dst_entry *inet_csk_route_req(struct sock *sk,
> security_req_classify_flow(req, &fl);
> if (ip_route_output_flow(net, &rt, &fl, sk, 0))
> goto no_route;
> - if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
> + if (opt && opt->opt.is_strictroute && rt->rt_dst != rt->rt_gateway)
> goto route_err;
> return &rt->u.dst;
>
> diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
> index 94bf105..8a95972 100644
> --- a/net/ipv4/ip_options.c
> +++ b/net/ipv4/ip_options.c
> @@ -35,7 +35,7 @@
> * saddr is address of outgoing interface.
> */
>
> -void ip_options_build(struct sk_buff * skb, struct ip_options * opt,
> +void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
> __be32 daddr, struct rtable *rt, int is_frag)
> {
> unsigned char *iph = skb_network_header(skb);
> @@ -82,9 +82,9 @@ void ip_options_build(struct sk_buff * skb, struct ip_options * opt,
> * NOTE: dopt cannot point to skb.
> */
>
> -int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb)
> +int ip_options_echo(struct ip_options *dopt, struct sk_buff *skb)
> {
> - struct ip_options *sopt;
> + const struct ip_options *sopt;
> unsigned char *sptr, *dptr;
> int soffset, doffset;
> int optlen;
> @@ -94,10 +94,8 @@ int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb)
>
> sopt = &(IPCB(skb)->opt);
>
> - if (sopt->optlen == 0) {
> - dopt->optlen = 0;
> + if (sopt->optlen == 0)
> return 0;
> - }
>
> sptr = skb_network_header(skb);
> dptr = dopt->__data;
> @@ -156,7 +154,7 @@ int ip_options_echo(struct ip_options * dopt, struct sk_buff * skb)
> dopt->optlen += optlen;
> }
> if (sopt->srr) {
> - unsigned char * start = sptr+sopt->srr;
> + unsigned char *start = sptr+sopt->srr;
> __be32 faddr;
>
> optlen = start[1];
> @@ -499,19 +497,19 @@ void ip_options_undo(struct ip_options * opt)
> }
> }
>
> -static struct ip_options *ip_options_get_alloc(const int optlen)
> +static struct ip_options_rcu *ip_options_get_alloc(const int optlen)
> {
> - return kzalloc(sizeof(struct ip_options) + ((optlen + 3) & ~3),
> + return kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
> GFP_KERNEL);
> }
>
> -static int ip_options_get_finish(struct net *net, struct ip_options **optp,
> - struct ip_options *opt, int optlen)
> +static int ip_options_get_finish(struct net *net, struct ip_options_rcu **optp,
> + struct ip_options_rcu *opt, int optlen)
> {
> while (optlen & 3)
> - opt->__data[optlen++] = IPOPT_END;
> - opt->optlen = optlen;
> - if (optlen && ip_options_compile(net, opt, NULL)) {
> + opt->opt.__data[optlen++] = IPOPT_END;
> + opt->opt.optlen = optlen;
> + if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
> kfree(opt);
> return -EINVAL;
> }
> @@ -520,29 +518,29 @@ static int ip_options_get_finish(struct net *net, struct ip_options **optp,
> return 0;
> }
>
> -int ip_options_get_from_user(struct net *net, struct ip_options **optp,
> +int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
> unsigned char __user *data, int optlen)
> {
> - struct ip_options *opt = ip_options_get_alloc(optlen);
> + struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
>
> if (!opt)
> return -ENOMEM;
> - if (optlen && copy_from_user(opt->__data, data, optlen)) {
> + if (optlen && copy_from_user(opt->opt.__data, data, optlen)) {
> kfree(opt);
> return -EFAULT;
> }
> return ip_options_get_finish(net, optp, opt, optlen);
> }
>
> -int ip_options_get(struct net *net, struct ip_options **optp,
> +int ip_options_get(struct net *net, struct ip_options_rcu **optp,
> unsigned char *data, int optlen)
> {
> - struct ip_options *opt = ip_options_get_alloc(optlen);
> + struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
>
> if (!opt)
> return -ENOMEM;
> if (optlen)
> - memcpy(opt->__data, data, optlen);
> + memcpy(opt->opt.__data, data, optlen);
> return ip_options_get_finish(net, optp, opt, optlen);
> }
>
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 44b7910..7dde039 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -137,14 +137,14 @@ static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
> *
> */
> int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
> - __be32 saddr, __be32 daddr, struct ip_options *opt)
> + __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
> {
> struct inet_sock *inet = inet_sk(sk);
> struct rtable *rt = skb_rtable(skb);
> struct iphdr *iph;
>
> /* Build the IP header. */
> - skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
> + skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
> skb_reset_network_header(skb);
> iph = ip_hdr(skb);
> iph->version = 4;
> @@ -160,9 +160,9 @@ int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
> iph->protocol = sk->sk_protocol;
> ip_select_ident(iph, &rt->u.dst, sk);
>
> - if (opt && opt->optlen) {
> - iph->ihl += opt->optlen>>2;
> - ip_options_build(skb, opt, daddr, rt, 0);
> + if (opt && opt->opt.optlen) {
> + iph->ihl += opt->opt.optlen>>2;
> + ip_options_build(skb, &opt->opt, daddr, rt, 0);
> }
>
> skb->priority = sk->sk_priority;
> @@ -312,9 +312,10 @@ int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
> {
> struct sock *sk = skb->sk;
> struct inet_sock *inet = inet_sk(sk);
> - struct ip_options *opt = inet->opt;
> + struct ip_options_rcu *inet_opt = NULL;
> struct rtable *rt;
> struct iphdr *iph;
> + int res;
>
> /* Skip all of this if the packet is already routed,
> * f.e. by something like SCTP.
> @@ -325,13 +326,15 @@ int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
>
> /* Make sure we can route this packet. */
> rt = (struct rtable *)__sk_dst_check(sk, 0);
> + rcu_read_lock();
> + inet_opt = rcu_dereference(inet->inet_opt);
> if (rt == NULL) {
> __be32 daddr;
>
> /* Use correct destination address if we have options. */
> daddr = inet->daddr;
> - if(opt && opt->srr)
> - daddr = opt->faddr;
> + if (inet_opt && inet_opt->opt.srr)
> + daddr = inet_opt->opt.faddr;
>
> {
> struct flowi fl = { .oif = sk->sk_bound_dev_if,
> @@ -359,11 +362,11 @@ int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
> skb_dst_set(skb, dst_clone(&rt->u.dst));
>
> packet_routed:
> - if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
> + if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_dst != rt->rt_gateway)
> goto no_route;
>
> /* OK, we know where to send it, allocate and build IP header. */
> - skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
> + skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
> skb_reset_network_header(skb);
> iph = ip_hdr(skb);
> *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
> @@ -377,9 +380,9 @@ packet_routed:
> iph->daddr = rt->rt_dst;
> /* Transport layer set skb->h.foo itself. */
>
> - if (opt && opt->optlen) {
> - iph->ihl += opt->optlen >> 2;
> - ip_options_build(skb, opt, inet->daddr, rt, 0);
> + if (inet_opt && inet_opt->opt.optlen) {
> + iph->ihl += inet_opt->opt.optlen >> 2;
> + ip_options_build(skb, &inet_opt->opt, inet->daddr, rt, 0);
> }
>
> ip_select_ident_more(iph, &rt->u.dst, sk,
> @@ -387,10 +390,12 @@ packet_routed:
>
> skb->priority = sk->sk_priority;
> skb->mark = sk->sk_mark;
> -
> - return ip_local_out(skb);
> + res = ip_local_out(skb);
> + rcu_read_unlock();
> + return res;
>
> no_route:
> + rcu_read_unlock();
> IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
> kfree_skb(skb);
> return -EHOSTUNREACH;
> @@ -809,7 +814,7 @@ int ip_append_data(struct sock *sk,
> /*
> * setup for corking.
> */
> - opt = ipc->opt;
> + opt = ipc->opt ? &ipc->opt->opt : NULL;
> if (opt) {
> if (inet->cork.opt == NULL) {
> inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
> @@ -1367,26 +1372,23 @@ void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *ar
> unsigned int len)
> {
> struct inet_sock *inet = inet_sk(sk);
> - struct {
> - struct ip_options opt;
> - char data[40];
> - } replyopts;
> + struct ip_options_data replyopts;
> struct ipcm_cookie ipc;
> __be32 daddr;
> struct rtable *rt = skb_rtable(skb);
>
> - if (ip_options_echo(&replyopts.opt, skb))
> + if (ip_options_echo(&replyopts.opt.opt, skb))
> return;
>
> daddr = ipc.addr = rt->rt_src;
> ipc.opt = NULL;
> ipc.shtx.flags = 0;
>
> - if (replyopts.opt.optlen) {
> + if (replyopts.opt.opt.optlen) {
> ipc.opt = &replyopts.opt;
>
> - if (ipc.opt->srr)
> - daddr = replyopts.opt.faddr;
> + if (replyopts.opt.opt.srr)
> + daddr = replyopts.opt.opt.faddr;
> }
>
> {
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index 184a7ad..099e6c3 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -434,6 +434,11 @@ out:
> }
>
>
> +static void opt_kfree_rcu(struct rcu_head *head)
> +{
> + kfree(container_of(head, struct ip_options_rcu, rcu));
> +}
> +
> /*
> * Socket option code for IP. This is the end of the line after any
> * TCP,UDP etc options on an IP socket.
> @@ -479,13 +484,15 @@ static int do_ip_setsockopt(struct sock *sk, int level,
> switch (optname) {
> case IP_OPTIONS:
> {
> - struct ip_options *opt = NULL;
> + struct ip_options_rcu *old, *opt = NULL;
> +
> if (optlen > 40 || optlen < 0)
> goto e_inval;
> err = ip_options_get_from_user(sock_net(sk), &opt,
> optval, optlen);
> if (err)
> break;
> + old = inet->inet_opt;
> if (inet->is_icsk) {
> struct inet_connection_sock *icsk = inet_csk(sk);
> #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
> @@ -494,17 +501,18 @@ static int do_ip_setsockopt(struct sock *sk, int level,
> (TCPF_LISTEN | TCPF_CLOSE)) &&
> inet->daddr != LOOPBACK4_IPV6)) {
> #endif
> - if (inet->opt)
> - icsk->icsk_ext_hdr_len -= inet->opt->optlen;
> + if (old)
> + icsk->icsk_ext_hdr_len -= old->opt.optlen;
> if (opt)
> - icsk->icsk_ext_hdr_len += opt->optlen;
> + icsk->icsk_ext_hdr_len += opt->opt.optlen;
> icsk->icsk_sync_mss(sk, icsk->icsk_pmtu_cookie);
> #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
> }
> #endif
> }
> - opt = xchg(&inet->opt, opt);
> - kfree(opt);
> + rcu_assign_pointer(inet->inet_opt, opt);
> + if (old)
> + call_rcu(&old->rcu, opt_kfree_rcu);
> break;
> }
> case IP_PKTINFO:
> @@ -1032,12 +1040,15 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname,
> case IP_OPTIONS:
> {
> unsigned char optbuf[sizeof(struct ip_options)+40];
> - struct ip_options * opt = (struct ip_options *)optbuf;
> + struct ip_options *opt = (struct ip_options *)optbuf;
> + struct ip_options_rcu *inet_opt;
> +
> + inet_opt = inet->inet_opt;
> opt->optlen = 0;
> - if (inet->opt)
> - memcpy(optbuf, inet->opt,
> - sizeof(struct ip_options)+
> - inet->opt->optlen);
> + if (inet_opt)
> + memcpy(optbuf, &inet_opt->opt,
> + sizeof(struct ip_options) +
> + inet_opt->opt.optlen);
> release_sock(sk);
>
> if (opt->optlen == 0)
> diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
> index ab996f9..07ab583 100644
> --- a/net/ipv4/raw.c
> +++ b/net/ipv4/raw.c
> @@ -459,6 +459,7 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
> __be32 saddr;
> u8 tos;
> int err;
> + struct ip_options_data opt_copy;
>
> err = -EMSGSIZE;
> if (len > 0xFFFF)
> @@ -519,8 +520,18 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
> saddr = ipc.addr;
> ipc.addr = daddr;
>
> - if (!ipc.opt)
> - ipc.opt = inet->opt;
> + if (!ipc.opt) {
> + struct ip_options_rcu *inet_opt;
> +
> + rcu_read_lock();
> + inet_opt = rcu_dereference(inet->inet_opt);
> + if (inet_opt) {
> + memcpy(&opt_copy, inet_opt,
> + sizeof(*inet_opt) + inet_opt->opt.optlen);
> + ipc.opt = &opt_copy.opt;
> + }
> + rcu_read_unlock();
> + }
>
> if (ipc.opt) {
> err = -EINVAL;
> @@ -529,10 +540,10 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
> */
> if (inet->hdrincl)
> goto done;
> - if (ipc.opt->srr) {
> + if (ipc.opt->opt.srr) {
> if (!daddr)
> goto done;
> - daddr = ipc.opt->faddr;
> + daddr = ipc.opt->opt.faddr;
> }
> }
> tos = RT_CONN_FLAGS(sk);
> diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
> index a6e0e07..0a94b64 100644
> --- a/net/ipv4/syncookies.c
> +++ b/net/ipv4/syncookies.c
> @@ -309,10 +309,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
> * the ACK carries the same options again (see RFC1122 4.2.3.8)
> */
> if (opt && opt->optlen) {
> - int opt_size = sizeof(struct ip_options) + opt->optlen;
> + int opt_size = sizeof(struct ip_options_rcu) + opt->optlen;
>
> ireq->opt = kmalloc(opt_size, GFP_ATOMIC);
> - if (ireq->opt != NULL && ip_options_echo(ireq->opt, skb)) {
> + if (ireq->opt != NULL && ip_options_echo(&ireq->opt->opt, skb)) {
> kfree(ireq->opt);
> ireq->opt = NULL;
> }
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 6a4e832..d746d3b3 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -152,6 +152,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> __be32 daddr, nexthop;
> int tmp;
> int err;
> + struct ip_options_rcu *inet_opt;
>
> if (addr_len < sizeof(struct sockaddr_in))
> return -EINVAL;
> @@ -160,10 +161,11 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> return -EAFNOSUPPORT;
>
> nexthop = daddr = usin->sin_addr.s_addr;
> - if (inet->opt && inet->opt->srr) {
> + inet_opt = inet->inet_opt;
> + if (inet_opt && inet_opt->opt.srr) {
> if (!daddr)
> return -EINVAL;
> - nexthop = inet->opt->faddr;
> + nexthop = inet_opt->opt.faddr;
> }
>
> tmp = ip_route_connect(&rt, nexthop, inet->saddr,
> @@ -181,7 +183,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> return -ENETUNREACH;
> }
>
> - if (!inet->opt || !inet->opt->srr)
> + if (!inet_opt || !inet_opt->opt.srr)
> daddr = rt->rt_dst;
>
> if (!inet->saddr)
> @@ -215,8 +217,8 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
> inet->daddr = daddr;
>
> inet_csk(sk)->icsk_ext_hdr_len = 0;
> - if (inet->opt)
> - inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
> + if (inet_opt)
> + inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
>
> tp->rx_opt.mss_clamp = 536;
>
> @@ -802,17 +804,18 @@ static void syn_flood_warning(struct sk_buff *skb)
> /*
> * Save and compile IPv4 options into the request_sock if needed.
> */
> -static struct ip_options *tcp_v4_save_options(struct sock *sk,
> - struct sk_buff *skb)
> +static struct ip_options_rcu *tcp_v4_save_options(struct sock *sk,
> + struct sk_buff *skb)
> {
> - struct ip_options *opt = &(IPCB(skb)->opt);
> - struct ip_options *dopt = NULL;
> + const struct ip_options *opt = &(IPCB(skb)->opt);
> + struct ip_options_rcu *dopt = NULL;
>
> if (opt && opt->optlen) {
> - int opt_size = optlength(opt);
> + int opt_size = sizeof(*dopt) + opt->optlen;
> +
> dopt = kmalloc(opt_size, GFP_ATOMIC);
> if (dopt) {
> - if (ip_options_echo(dopt, skb)) {
> + if (ip_options_echo(&dopt->opt, skb)) {
> kfree(dopt);
> dopt = NULL;
> }
> @@ -1362,6 +1365,7 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
> #ifdef CONFIG_TCP_MD5SIG
> struct tcp_md5sig_key *key;
> #endif
> + struct ip_options_rcu *inet_opt;
>
> if (sk_acceptq_is_full(sk))
> goto exit_overflow;
> @@ -1382,13 +1386,14 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
> newinet->daddr = ireq->rmt_addr;
> newinet->rcv_saddr = ireq->loc_addr;
> newinet->saddr = ireq->loc_addr;
> - newinet->opt = ireq->opt;
> + inet_opt = ireq->opt;
> + rcu_assign_pointer(newinet->inet_opt, inet_opt);
> ireq->opt = NULL;
> newinet->mc_index = inet_iif(skb);
> newinet->mc_ttl = ip_hdr(skb)->ttl;
> inet_csk(newsk)->icsk_ext_hdr_len = 0;
> - if (newinet->opt)
> - inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
> + if (inet_opt)
> + inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
> newinet->id = newtp->write_seq ^ jiffies;
>
> tcp_mtup_init(newsk);
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 8e28770..af559e0 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -592,6 +592,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
> int err, is_udplite = IS_UDPLITE(sk);
> int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
> int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
> + struct ip_options_data opt_copy;
>
> if (len > 0xFFFF)
> return -EMSGSIZE;
> @@ -663,22 +664,32 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
> free = 1;
> connected = 0;
> }
> - if (!ipc.opt)
> - ipc.opt = inet->opt;
> + if (!ipc.opt) {
> + struct ip_options_rcu *inet_opt;
> +
> + rcu_read_lock();
> + inet_opt = rcu_dereference(inet->inet_opt);
> + if (inet_opt) {
> + memcpy(&opt_copy, inet_opt,
> + sizeof(*inet_opt) + inet_opt->opt.optlen);
> + ipc.opt = &opt_copy.opt;
> + }
> + rcu_read_unlock();
> + }
>
> saddr = ipc.addr;
> ipc.addr = faddr = daddr;
>
> - if (ipc.opt && ipc.opt->srr) {
> + if (ipc.opt && ipc.opt->opt.srr) {
> if (!daddr)
> return -EINVAL;
> - faddr = ipc.opt->faddr;
> + faddr = ipc.opt->opt.faddr;
> connected = 0;
> }
> tos = RT_TOS(inet->tos);
> if (sock_flag(sk, SOCK_LOCALROUTE) ||
> (msg->msg_flags & MSG_DONTROUTE) ||
> - (ipc.opt && ipc.opt->is_strictroute)) {
> + (ipc.opt && ipc.opt->opt.is_strictroute)) {
> tos |= RTO_ONLINK;
> connected = 0;
> }
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index faae6df..1b25191 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -1391,7 +1391,7 @@ static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
>
> First: no IPv4 options.
> */
> - newinet->opt = NULL;
> + newinet->inet_opt = NULL;
> newnp->ipv6_fl_list = NULL;
>
> /* Clone RX bits */

--
Ben Hutchings
Theory and practice are closer in theory than in practice.
- John Levine, moderator of comp.compilers

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