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inet: add RCU protection to inet->opt

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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@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-04-21 09:45:37 +00:00 • committed by David S. Miller
parent 0a14842f5a
commit f6d8bd051c
17 changed files with 241 additions and 168 deletions
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11
include/net/ip.h
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@ -52,7 +52,7 @@ static inline unsigned int ip_hdrlen(const struct sk_buff *skb)
struct ipcm_cookie {
__be32 addr;
int oif;
struct ip_options *opt;
struct ip_options_rcu *opt;
__u8 tx_flags;
};
@ -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);
@ -416,14 +416,15 @@ 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);