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authorEric Dumazet <edumazet@google.com>2015-11-29 19:37:57 -0800
committerDavid S. Miller <davem@davemloft.net>2015-12-02 23:37:16 -0500
commit45f6fad84cc305103b28d73482b344d7f5b76f39 (patch)
tree283dbc3a6cd4a26288a3526d0de48cf8c2e27b75 /include/net
parent01b3f52157ff5a47d6d8d796f396a4b34a53c61d (diff)
ipv6: add complete rcu protection around np->opt
This patch addresses multiple problems : UDP/RAW sendmsg() need to get a stable struct ipv6_txoptions while socket is not locked : Other threads can change np->opt concurrently. Dmitry posted a syzkaller (http://github.com/google/syzkaller) program desmonstrating use-after-free. Starting with TCP/DCCP lockless listeners, tcp_v6_syn_recv_sock() and dccp_v6_request_recv_sock() also need to use RCU protection to dereference np->opt once (before calling ipv6_dup_options()) This patch adds full RCU protection to np->opt Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/ipv6.h21
1 files changed, 20 insertions, 1 deletions
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index ea5a13ef85a6..9a5c9f013784 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -205,6 +205,7 @@ extern rwlock_t ip6_ra_lock;
*/
struct ipv6_txoptions {
+ atomic_t refcnt;
/* Length of this structure */
int tot_len;
@@ -217,7 +218,7 @@ struct ipv6_txoptions {
struct ipv6_opt_hdr *dst0opt;
struct ipv6_rt_hdr *srcrt; /* Routing Header */
struct ipv6_opt_hdr *dst1opt;
-
+ struct rcu_head rcu;
/* Option buffer, as read by IPV6_PKTOPTIONS, starts here. */
};
@@ -252,6 +253,24 @@ struct ipv6_fl_socklist {
struct rcu_head rcu;
};
+static inline struct ipv6_txoptions *txopt_get(const struct ipv6_pinfo *np)
+{
+ struct ipv6_txoptions *opt;
+
+ rcu_read_lock();
+ opt = rcu_dereference(np->opt);
+ if (opt && !atomic_inc_not_zero(&opt->refcnt))
+ opt = NULL;
+ rcu_read_unlock();
+ return opt;
+}
+
+static inline void txopt_put(struct ipv6_txoptions *opt)
+{
+ if (opt && atomic_dec_and_test(&opt->refcnt))
+ kfree_rcu(opt, rcu);
+}
+
struct ip6_flowlabel *fl6_sock_lookup(struct sock *sk, __be32 label);
struct ipv6_txoptions *fl6_merge_options(struct ipv6_txoptions *opt_space,
struct ip6_flowlabel *fl,