From f6d8bd051c391c1c0458a30b2a7abcd939329259 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 21 Apr 2011 09:45:37 +0000 Subject: inet: add RCU protection to inet->opt 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 Cc: Herbert Xu Signed-off-by: David S. Miller --- net/ipv4/icmp.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) (limited to 'net/ipv4/icmp.c') diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 74e35e5736e..cfeca3c2152 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -108,8 +108,7 @@ 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. */ @@ -333,7 +332,7 @@ 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); @@ -347,10 +346,10 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) daddr = ipc.addr = rt->rt_src; ipc.opt = NULL; ipc.tx_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 flowi4 fl4 = { @@ -379,8 +378,8 @@ static struct rtable *icmp_route_lookup(struct net *net, struct sk_buff *skb_in, struct icmp_bxm *param) { struct flowi4 fl4 = { - .daddr = (param->replyopts.srr ? - param->replyopts.faddr : iph->saddr), + .daddr = (param->replyopts.opt.opt.srr ? + param->replyopts.opt.opt.faddr : iph->saddr), .saddr = saddr, .flowi4_tos = RT_TOS(tos), .flowi4_proto = IPPROTO_ICMP, @@ -581,7 +580,7 @@ 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; @@ -597,7 +596,7 @@ 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.tx_flags = 0; rt = icmp_route_lookup(net, skb_in, iph, saddr, tos, @@ -613,7 +612,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) room = dst_mtu(&rt->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; -- cgit v1.2.3