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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 /net/ipv6/ipv6_sockglue.c
parent01b3f52157ff5a47d6d8d796f396a4b34a53c61d (diff)
downloadlinux-45f6fad84cc305103b28d73482b344d7f5b76f39.tar.bz2
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 'net/ipv6/ipv6_sockglue.c')
-rw-r--r--net/ipv6/ipv6_sockglue.c33
1 files changed, 22 insertions, 11 deletions
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 63e6956917c9..4449ad1f8114 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -111,7 +111,8 @@ struct ipv6_txoptions *ipv6_update_options(struct sock *sk,
icsk->icsk_sync_mss(sk, icsk->icsk_pmtu_cookie);
}
}
- opt = xchg(&inet6_sk(sk)->opt, opt);
+ opt = xchg((__force struct ipv6_txoptions **)&inet6_sk(sk)->opt,
+ opt);
sk_dst_reset(sk);
return opt;
@@ -231,9 +232,12 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
sk->sk_socket->ops = &inet_dgram_ops;
sk->sk_family = PF_INET;
}
- opt = xchg(&np->opt, NULL);
- if (opt)
- sock_kfree_s(sk, opt, opt->tot_len);
+ opt = xchg((__force struct ipv6_txoptions **)&np->opt,
+ NULL);
+ if (opt) {
+ atomic_sub(opt->tot_len, &sk->sk_omem_alloc);
+ txopt_put(opt);
+ }
pktopt = xchg(&np->pktoptions, NULL);
kfree_skb(pktopt);
@@ -403,7 +407,8 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
if (optname != IPV6_RTHDR && !ns_capable(net->user_ns, CAP_NET_RAW))
break;
- opt = ipv6_renew_options(sk, np->opt, optname,
+ opt = rcu_dereference_protected(np->opt, sock_owned_by_user(sk));
+ opt = ipv6_renew_options(sk, opt, optname,
(struct ipv6_opt_hdr __user *)optval,
optlen);
if (IS_ERR(opt)) {
@@ -432,8 +437,10 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
retv = 0;
opt = ipv6_update_options(sk, opt);
sticky_done:
- if (opt)
- sock_kfree_s(sk, opt, opt->tot_len);
+ if (opt) {
+ atomic_sub(opt->tot_len, &sk->sk_omem_alloc);
+ txopt_put(opt);
+ }
break;
}
@@ -486,6 +493,7 @@ sticky_done:
break;
memset(opt, 0, sizeof(*opt));
+ atomic_set(&opt->refcnt, 1);
opt->tot_len = sizeof(*opt) + optlen;
retv = -EFAULT;
if (copy_from_user(opt+1, optval, optlen))
@@ -502,8 +510,10 @@ update:
retv = 0;
opt = ipv6_update_options(sk, opt);
done:
- if (opt)
- sock_kfree_s(sk, opt, opt->tot_len);
+ if (opt) {
+ atomic_sub(opt->tot_len, &sk->sk_omem_alloc);
+ txopt_put(opt);
+ }
break;
}
case IPV6_UNICAST_HOPS:
@@ -1110,10 +1120,11 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
case IPV6_RTHDR:
case IPV6_DSTOPTS:
{
+ struct ipv6_txoptions *opt;
lock_sock(sk);
- len = ipv6_getsockopt_sticky(sk, np->opt,
- optname, optval, len);
+ opt = rcu_dereference_protected(np->opt, sock_owned_by_user(sk));
+ len = ipv6_getsockopt_sticky(sk, opt, optname, optval, len);
release_sock(sk);
/* check if ipv6_getsockopt_sticky() returns err code */
if (len < 0)