> On Sep 14, 2018, at 1:20 PM, Yifeng Sun <[email protected]> wrote:
>
> @@ -1710,9 +1710,14 @@ static void ip6gre_destroy_tunnels(struct net *net,
> struct list_head *head)
> static int __net_init ip6gre_init_net(struct net *net)
> {
> struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);
> + const char *dev_name = "ovs-ip6gre0";
> int err;
>
> - ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0",
> + if (strlen(dev_name) > IFNAMSIZ)
> + return -E2BIG;
> +
> + ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip6_tnl),
> + dev_name,
> NET_NAME_UNKNOWN,
> ip6gre_tunnel_setup);
This string is allocated statically, so I don't think you need to do any checks
on its length.
> if (!ign->fb_tunnel_dev) {
> diff --git a/datapath/linux/compat/ip6_tunnel.c
> b/datapath/linux/compat/ip6_tunnel.c
> index 56fd8b4dd342..a7a1a586c920 100644
> --- a/datapath/linux/compat/ip6_tunnel.c
> +++ b/datapath/linux/compat/ip6_tunnel.c
> @@ -355,7 +355,7 @@ static struct ip6_tnl *ip6_tnl_create(struct net *net,
> struct __ip6_tnl_parm *p)
> if (p->name[0])
> strlcpy(name, p->name, IFNAMSIZ);
> else
> - sprintf(name, "ip6tnl%%d");
> + strlcpy(name, "ovs-ip6tnl%%d", IFNAMSIZ);
I think you need to drop one of the "%", since it changed from a sprintf() to a
strlcpy().
The string length concern I'd raised in v1 was around the run-time replacement
of these "%d" arguments. I checked with Greg, and he said that the number is
not greater than three digits, so we should be fine with this change, since we
have room for up to a five digit number.
> @@ -2087,13 +2087,17 @@ static int __net_init ip6_tnl_init_net(struct net
> *net)
> {
> struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
> struct ip6_tnl *t = NULL;
> + const char *dev_name = "ovs-ip6tnl0";
> int err;
>
> + if (strlen(dev_name) > IFNAMSIZ)
> + return -E2BIG;
> +
> ip6n->tnls[0] = ip6n->tnls_wc;
> ip6n->tnls[1] = ip6n->tnls_r_l;
>
> err = -ENOMEM;
> - ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6tnl0",
> + ip6n->fb_tnl_dev = alloc_netdev(sizeof(struct ip6_tnl), dev_name,
> NET_NAME_UNKNOWN, ip6_tnl_dev_setup);
Again, I don't think you need run-time checks for this statically allocated
string.
> static void __net_exit ipgre_tap_exit_net(struct net *net)
> diff --git a/datapath/linux/compat/ip_tunnel.c
> b/datapath/linux/compat/ip_tunnel.c
> index d16e60fbfef0..0da8a06ecd26 100644
> --- a/datapath/linux/compat/ip_tunnel.c
> +++ b/datapath/linux/compat/ip_tunnel.c
> @@ -130,11 +130,12 @@ static struct net_device *__ip_tunnel_create(struct net
> *net,
> if (parms->name[0])
> strlcpy(name, parms->name, IFNAMSIZ);
> else {
> - if (strlen(ops->kind) > (IFNAMSIZ - 3)) {
> + if (strlen(ops->kind) > (IFNAMSIZ - 7)) {
I think is correct that we need to increase this by four, since we added
"ovs-". However, if the largest replacement for "%d" is three digits, should
that check upstream be for "IFNAMESIZ - 4" to account for the nul-terminator?
This is a question that applies to the Linux kernel upstream, too.
> err = -E2BIG;
> goto failed;
> }
> - strlcpy(name, ops->kind, IFNAMSIZ);
> + strlcpy(name, "ovs-", IFNAMSIZ);
> + strlcat(name, ops->kind, IFNAMSIZ);
> strncat(name, "%d", 2);
This isn't new to your changes, but we've already done string length sanity
checks earlier, so these aren't adding much, and we don't even both with the
last one, which would be the most likely to overflow. Regardless, as we
discussed offline, it might be just cleaner to use sprintf() or snprintf().
--Justin
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