From: Pavel Emelyanov <xemul@parallels•com>
To: Brian Haley <brian.haley@hp•com>
Cc: David Miller <davem@davemloft•net>,
Eric Dumazet <eric.dumazet@gmail•com>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>
Subject: Re: [PATCH v2 net-next] sockopt: Change getsockopt() of SO_BINDTODEVICE to return an interface name
Date: Sat, 17 Nov 2012 09:06:24 +0400 [thread overview]
Message-ID: <50A71B50.3030603@parallels.com> (raw)
In-Reply-To: <50A6A8FB.3050901@hp.com>
> @@ -4165,6 +4180,8 @@ static int dev_ifname(struct net *net, struct ifreq __user
> *arg)
>
> strcpy(ifr.ifr_name, dev->name);
> rcu_read_unlock();
> + if (read_seqretry(&devnet_rename_seq, seq))
> + goto retry;
I believe it makes sense to make the seqcount protection as a separate patch
with description of what may happen.
>
> if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
> return -EFAULT;
> @@ -562,6 +563,59 @@ out:
> return ret;
> }
>
> +static int sock_getbindtodevice(struct sock *sk, char __user *optval,
> + int __user *optlen, int len)
> +{
> + int ret = -ENOPROTOOPT;
> +#ifdef CONFIG_NETDEVICES
> + struct net *net = sock_net(sk);
> + struct net_device *dev;
> + char devname[IFNAMSIZ];
> + unsigned seq;
> +
> + if (sk->sk_bound_dev_if == 0) {
> + len = 0;
> + goto zero;
> + }
> +
> + ret = -EINVAL;
> + if (len < IFNAMSIZ)
> + goto out;
> +
> +retry:
> + seq = read_seqbegin(&devnet_rename_seq);
> + rcu_read_lock();
> + dev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if);
The sk->sk_bound_dev_if might have changed to 0 while we did read_seqretry (or
did the len check above, but the race window is smaller) and this code will
report -ENODEV instead of zero lenght.
Other than this, the intention looks OK to me.
> + ret = -ENODEV;
> + if (!dev) {
> + rcu_read_unlock();
> + goto out;
> + }
> +
> + strcpy(devname, dev->name);
> + rcu_read_unlock();
> + if (read_seqretry(&devnet_rename_seq, seq))
> + goto retry;
> +
> + len = strlen(devname) + 1;
> +
> + ret = -EFAULT;
> + if (copy_to_user(optval, devname, len))
> + goto out;
> +
Thanks,
Pavel
next prev parent reply other threads:[~2012-11-17 5:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-16 20:58 [PATCH v2 net-next] sockopt: Change getsockopt() of SO_BINDTODEVICE to return an interface name Brian Haley
2012-11-17 5:06 ` Pavel Emelyanov [this message]
2012-11-17 21:58 ` Brian Haley
2012-11-20 18:58 ` David Miller
2012-11-26 15:10 ` Brian Haley
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