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authorMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>2015-06-12 10:16:41 -0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-01 12:07:34 +0200
commit7bf24986e3c2e4b818be4a6172aebb3784c6bcda (patch)
tree7e31fcc29f9eadb37ce17398527af4f2fa81a78d
parent61cabc7d549fde1afddac0efbbf03a5c63161b33 (diff)
downloadlinux-linaro-stable-7bf24986e3c2e4b818be4a6172aebb3784c6bcda.tar.gz
sctp: fix ASCONF list handling
commit 2d45a02d0166caf2627fe91897c6ffc3b19514c4 upstream. ->auto_asconf_splist is per namespace and mangled by functions like sctp_setsockopt_auto_asconf() which doesn't guarantee any serialization. Also, the call to inet_sk_copy_descendant() was backuping ->auto_asconf_list through the copy but was not honoring ->do_auto_asconf, which could lead to list corruption if it was different between both sockets. This commit thus fixes the list handling by using ->addr_wq_lock spinlock to protect the list. A special handling is done upon socket creation and destruction for that. Error handlig on sctp_init_sock() will never return an error after having initialized asconf, so sctp_destroy_sock() can be called without addrq_wq_lock. The lock now will be take on sctp_close_sock(), before locking the socket, so we don't do it in inverse order compared to sctp_addr_wq_timeout_handler(). Instead of taking the lock on sctp_sock_migrate() for copying and restoring the list values, it's preferred to avoid rewritting it by implementing sctp_copy_descendant(). Issue was found with a test application that kept flipping sysctl default_auto_asconf on and off, but one could trigger it by issuing simultaneous setsockopt() calls on multiple sockets or by creating/destroying sockets fast enough. This is only triggerable locally. Fixes: 9f7d653b67ae ("sctp: Add Auto-ASCONF support (core).") Reported-by: Ji Jianwen <jiji@redhat.com> Suggested-by: Neil Horman <nhorman@tuxdriver.com> Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> [wangkai: backport to 3.10: adjust context] Signed-off-by: Wang Kai <morgan.wang@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/net/netns/sctp.h1
-rw-r--r--include/net/sctp/structs.h4
-rw-r--r--net/sctp/socket.c43
3 files changed, 37 insertions, 11 deletions
diff --git a/include/net/netns/sctp.h b/include/net/netns/sctp.h
index 3573a81815ad..8ba379f9e467 100644
--- a/include/net/netns/sctp.h
+++ b/include/net/netns/sctp.h
@@ -31,6 +31,7 @@ struct netns_sctp {
struct list_head addr_waitq;
struct timer_list addr_wq_timer;
struct list_head auto_asconf_splist;
+ /* Lock that protects both addr_waitq and auto_asconf_splist */
spinlock_t addr_wq_lock;
/* Lock that protects the local_addr_list writers */
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index da6b9a01ff75..b30c1d95be2c 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -228,6 +228,10 @@ struct sctp_sock {
atomic_t pd_mode;
/* Receive to here while partial delivery is in effect. */
struct sk_buff_head pd_lobby;
+
+ /* These must be the last fields, as they will skipped on copies,
+ * like on accept and peeloff operations
+ */
struct list_head auto_asconf_list;
int do_auto_asconf;
};
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index dfb9b133e662..ec5766dc3946 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1548,8 +1548,10 @@ SCTP_STATIC void sctp_close(struct sock *sk, long timeout)
/* Supposedly, no process has access to the socket, but
* the net layers still may.
+ * Also, sctp_destroy_sock() needs to be called with addr_wq_lock
+ * held and that should be grabbed before socket lock.
*/
- sctp_local_bh_disable();
+ spin_lock_bh(&net->sctp.addr_wq_lock);
sctp_bh_lock_sock(sk);
/* Hold the sock, since sk_common_release() will put sock_put()
@@ -1559,7 +1561,7 @@ SCTP_STATIC void sctp_close(struct sock *sk, long timeout)
sk_common_release(sk);
sctp_bh_unlock_sock(sk);
- sctp_local_bh_enable();
+ spin_unlock_bh(&net->sctp.addr_wq_lock);
sock_put(sk);
@@ -3508,6 +3510,7 @@ static int sctp_setsockopt_auto_asconf(struct sock *sk, char __user *optval,
if ((val && sp->do_auto_asconf) || (!val && !sp->do_auto_asconf))
return 0;
+ spin_lock_bh(&sock_net(sk)->sctp.addr_wq_lock);
if (val == 0 && sp->do_auto_asconf) {
list_del(&sp->auto_asconf_list);
sp->do_auto_asconf = 0;
@@ -3516,6 +3519,7 @@ static int sctp_setsockopt_auto_asconf(struct sock *sk, char __user *optval,
&sock_net(sk)->sctp.auto_asconf_splist);
sp->do_auto_asconf = 1;
}
+ spin_unlock_bh(&sock_net(sk)->sctp.addr_wq_lock);
return 0;
}
@@ -4007,18 +4011,28 @@ SCTP_STATIC int sctp_init_sock(struct sock *sk)
local_bh_disable();
percpu_counter_inc(&sctp_sockets_allocated);
sock_prot_inuse_add(net, sk->sk_prot, 1);
+
+ /* Nothing can fail after this block, otherwise
+ * sctp_destroy_sock() will be called without addr_wq_lock held
+ */
if (net->sctp.default_auto_asconf) {
+ spin_lock(&sock_net(sk)->sctp.addr_wq_lock);
list_add_tail(&sp->auto_asconf_list,
&net->sctp.auto_asconf_splist);
sp->do_auto_asconf = 1;
- } else
+ spin_unlock(&sock_net(sk)->sctp.addr_wq_lock);
+ } else {
sp->do_auto_asconf = 0;
+ }
+
local_bh_enable();
return 0;
}
-/* Cleanup any SCTP per socket resources. */
+/* Cleanup any SCTP per socket resources. Must be called with
+ * sock_net(sk)->sctp.addr_wq_lock held if sp->do_auto_asconf is true
+ */
SCTP_STATIC void sctp_destroy_sock(struct sock *sk)
{
struct sctp_sock *sp;
@@ -6957,6 +6971,19 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk,
newinet->mc_list = NULL;
}
+static inline void sctp_copy_descendant(struct sock *sk_to,
+ const struct sock *sk_from)
+{
+ int ancestor_size = sizeof(struct inet_sock) +
+ sizeof(struct sctp_sock) -
+ offsetof(struct sctp_sock, auto_asconf_list);
+
+ if (sk_from->sk_family == PF_INET6)
+ ancestor_size += sizeof(struct ipv6_pinfo);
+
+ __inet_sk_copy_descendant(sk_to, sk_from, ancestor_size);
+}
+
/* Populate the fields of the newsk from the oldsk and migrate the assoc
* and its messages to the newsk.
*/
@@ -6971,7 +6998,6 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
struct sk_buff *skb, *tmp;
struct sctp_ulpevent *event;
struct sctp_bind_hashbucket *head;
- struct list_head tmplist;
/* Migrate socket buffer sizes and all the socket level options to the
* new socket.
@@ -6979,12 +7005,7 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
newsk->sk_sndbuf = oldsk->sk_sndbuf;
newsk->sk_rcvbuf = oldsk->sk_rcvbuf;
/* Brute force copy old sctp opt. */
- if (oldsp->do_auto_asconf) {
- memcpy(&tmplist, &newsp->auto_asconf_list, sizeof(tmplist));
- inet_sk_copy_descendant(newsk, oldsk);
- memcpy(&newsp->auto_asconf_list, &tmplist, sizeof(tmplist));
- } else
- inet_sk_copy_descendant(newsk, oldsk);
+ sctp_copy_descendant(newsk, oldsk);
/* Restore the ep value that was overwritten with the above structure
* copy.