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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: 9f7d653b67 ("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>
This commit is contained in:
Marcelo Ricardo Leitner 2015-06-12 10:16:41 -03:00 committed by Greg Kroah-Hartman
parent 61cabc7d54
commit 7bf24986e3
3 changed files with 37 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/netns/sctp.h
View File

@ -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 */

4
include/net/sctp/structs.h
View File

@ -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;
};

43
net/sctp/socket.c
View File

@ -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.