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| author | Eric Dumazet <edumazet@google.com> | 2015-11-29 19:37:57 -0800 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2016-01-05 16:11:14 +0100 |
| commit | 71781d1f85bc02bcdb29b18e9e76f1d49118ddc8 (patch) | |
| tree | a65443d65688c5e6258b4fe084becf9951ec1e2f /include | |
| parent | eac843e433fe2b8c25b55a0cf4294b12f05742e9 (diff) | |
| download | lwn-71781d1f85bc02bcdb29b18e9e76f1d49118ddc8.tar.gz lwn-71781d1f85bc02bcdb29b18e9e76f1d49118ddc8.zip | |
ipv6: add complete rcu protection around np->opt
[ Upstream commit 45f6fad84cc305103b28d73482b344d7f5b76f39 ]
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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/ipv6.h | 2 | ||||
| -rw-r--r-- | include/net/ipv6.h | 21 |
2 files changed, 21 insertions, 2 deletions
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index 28ea38439313..88c0cf0079ad 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -220,7 +220,7 @@ struct ipv6_pinfo { struct ipv6_ac_socklist *ipv6_ac_list; struct ipv6_fl_socklist __rcu *ipv6_fl_list; - struct ipv6_txoptions *opt; + struct ipv6_txoptions __rcu *opt; struct sk_buff *pktoptions; struct sk_buff *rxpmtu; struct { diff --git a/include/net/ipv6.h b/include/net/ipv6.h index e9ca7fd12aa3..7d4130a75872 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -201,6 +201,7 @@ extern rwlock_t ip6_ra_lock; */ struct ipv6_txoptions { + atomic_t refcnt; /* Length of this structure */ int tot_len; @@ -213,7 +214,7 @@ 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. */ }; @@ -244,6 +245,24 @@ 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); +} + extern struct ip6_flowlabel *fl6_sock_lookup(struct sock *sk, __be32 label); extern struct ipv6_txoptions *fl6_merge_options(struct ipv6_txoptions * opt_space, struct ip6_flowlabel * fl, |