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/ip_options.c | 38 ++++++++++++++++++-------------------- 1 file changed, 18 insertions(+), 20 deletions(-) (limited to 'net/ipv4/ip_options.c') diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c index 2391b24e8251..01fc40965848 100644 --- a/net/ipv4/ip_options.c +++ b/net/ipv4/ip_options.c @@ -36,7 +36,7 @@ * 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); @@ -83,9 +83,9 @@ 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; @@ -95,10 +95,8 @@ 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; @@ -157,7 +155,7 @@ 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); } -- cgit v1.2.3