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Merge branch 'rtnetlink-avoid-a-warning-in-rtnl_newlink'
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Jakub Kicinski says:

====================
rtnetlink: avoid a warning in rtnl_newlink()

I've been hoping for some time that someone more competent would fix
the stack frame size warning in rtnl_newlink(), but looks like I'll
have to take a stab at it myself :)  That's the only warning I see
in most of my builds.

First patch refactors away a somewhat surprising if (1) code block.
Reindentation will most likely cause cherry-pick problems but OTOH
rtnl_newlink() doesn't seem to be changed often, so perhaps we can
risk it in the name of cleaner code?

Second patch fixes the warning in simplest possible way.  I was
pondering if there is any more clever solution, but I can't see it..
rtnl_newlink() is quite long with a lot of possible execution paths
so doing memory allocations half way through leads to very ugly
results.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Nov 30, 2018
2 parents 74315c3 + a293974 commit dd35420
Showing 1 changed file with 170 additions and 161 deletions.
331 changes: 170 additions & 161 deletions net/core/rtnetlink.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2971,20 +2971,24 @@ static int rtnl_group_changelink(const struct sk_buff *skb,
return 0;
}

static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
struct nlattr **attr, struct netlink_ext_ack *extack)
{
struct nlattr *slave_attr[RTNL_SLAVE_MAX_TYPE + 1];
unsigned char name_assign_type = NET_NAME_USER;
struct nlattr *linkinfo[IFLA_INFO_MAX + 1];
const struct rtnl_link_ops *m_ops = NULL;
struct net_device *master_dev = NULL;
struct net *net = sock_net(skb->sk);
const struct rtnl_link_ops *ops;
const struct rtnl_link_ops *m_ops = NULL;
struct nlattr *tb[IFLA_MAX + 1];
struct net *dest_net, *link_net;
struct nlattr **slave_data;
char kind[MODULE_NAME_LEN];
struct net_device *dev;
struct net_device *master_dev = NULL;
struct ifinfomsg *ifm;
char kind[MODULE_NAME_LEN];
char ifname[IFNAMSIZ];
struct nlattr *tb[IFLA_MAX+1];
struct nlattr *linkinfo[IFLA_INFO_MAX+1];
unsigned char name_assign_type = NET_NAME_USER;
struct nlattr **data;
int err;

#ifdef CONFIG_MODULES
Expand Down Expand Up @@ -3040,195 +3044,200 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
ops = NULL;
}

if (1) {
struct nlattr *attr[RTNL_MAX_TYPE + 1];
struct nlattr *slave_attr[RTNL_SLAVE_MAX_TYPE + 1];
struct nlattr **data = NULL;
struct nlattr **slave_data = NULL;
struct net *dest_net, *link_net = NULL;

if (ops) {
if (ops->maxtype > RTNL_MAX_TYPE)
return -EINVAL;
data = NULL;
if (ops) {
if (ops->maxtype > RTNL_MAX_TYPE)
return -EINVAL;

if (ops->maxtype && linkinfo[IFLA_INFO_DATA]) {
err = nla_parse_nested(attr, ops->maxtype,
linkinfo[IFLA_INFO_DATA],
ops->policy, extack);
if (err < 0)
return err;
data = attr;
}
if (ops->validate) {
err = ops->validate(tb, data, extack);
if (err < 0)
return err;
}
if (ops->maxtype && linkinfo[IFLA_INFO_DATA]) {
err = nla_parse_nested(attr, ops->maxtype,
linkinfo[IFLA_INFO_DATA],
ops->policy, extack);
if (err < 0)
return err;
data = attr;
}
if (ops->validate) {
err = ops->validate(tb, data, extack);
if (err < 0)
return err;
}
}

if (m_ops) {
if (m_ops->slave_maxtype > RTNL_SLAVE_MAX_TYPE)
return -EINVAL;
slave_data = NULL;
if (m_ops) {
if (m_ops->slave_maxtype > RTNL_SLAVE_MAX_TYPE)
return -EINVAL;

if (m_ops->slave_maxtype &&
linkinfo[IFLA_INFO_SLAVE_DATA]) {
err = nla_parse_nested(slave_attr,
m_ops->slave_maxtype,
linkinfo[IFLA_INFO_SLAVE_DATA],
m_ops->slave_policy,
extack);
if (err < 0)
return err;
slave_data = slave_attr;
}
if (m_ops->slave_maxtype &&
linkinfo[IFLA_INFO_SLAVE_DATA]) {
err = nla_parse_nested(slave_attr, m_ops->slave_maxtype,
linkinfo[IFLA_INFO_SLAVE_DATA],
m_ops->slave_policy, extack);
if (err < 0)
return err;
slave_data = slave_attr;
}
}

if (dev) {
int status = 0;

if (nlh->nlmsg_flags & NLM_F_EXCL)
return -EEXIST;
if (nlh->nlmsg_flags & NLM_F_REPLACE)
return -EOPNOTSUPP;
if (dev) {
int status = 0;

if (linkinfo[IFLA_INFO_DATA]) {
if (!ops || ops != dev->rtnl_link_ops ||
!ops->changelink)
return -EOPNOTSUPP;
if (nlh->nlmsg_flags & NLM_F_EXCL)
return -EEXIST;
if (nlh->nlmsg_flags & NLM_F_REPLACE)
return -EOPNOTSUPP;

err = ops->changelink(dev, tb, data, extack);
if (err < 0)
return err;
status |= DO_SETLINK_NOTIFY;
}
if (linkinfo[IFLA_INFO_DATA]) {
if (!ops || ops != dev->rtnl_link_ops ||
!ops->changelink)
return -EOPNOTSUPP;

if (linkinfo[IFLA_INFO_SLAVE_DATA]) {
if (!m_ops || !m_ops->slave_changelink)
return -EOPNOTSUPP;
err = ops->changelink(dev, tb, data, extack);
if (err < 0)
return err;
status |= DO_SETLINK_NOTIFY;
}

err = m_ops->slave_changelink(master_dev, dev,
tb, slave_data,
extack);
if (err < 0)
return err;
status |= DO_SETLINK_NOTIFY;
}
if (linkinfo[IFLA_INFO_SLAVE_DATA]) {
if (!m_ops || !m_ops->slave_changelink)
return -EOPNOTSUPP;

return do_setlink(skb, dev, ifm, extack, tb, ifname,
status);
err = m_ops->slave_changelink(master_dev, dev, tb,
slave_data, extack);
if (err < 0)
return err;
status |= DO_SETLINK_NOTIFY;
}

if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
if (ifm->ifi_index == 0 && tb[IFLA_GROUP])
return rtnl_group_changelink(skb, net,
return do_setlink(skb, dev, ifm, extack, tb, ifname, status);
}

if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
if (ifm->ifi_index == 0 && tb[IFLA_GROUP])
return rtnl_group_changelink(skb, net,
nla_get_u32(tb[IFLA_GROUP]),
ifm, extack, tb);
return -ENODEV;
}
return -ENODEV;
}

if (tb[IFLA_MAP] || tb[IFLA_PROTINFO])
return -EOPNOTSUPP;
if (tb[IFLA_MAP] || tb[IFLA_PROTINFO])
return -EOPNOTSUPP;

if (!ops) {
if (!ops) {
#ifdef CONFIG_MODULES
if (kind[0]) {
__rtnl_unlock();
request_module("rtnl-link-%s", kind);
rtnl_lock();
ops = rtnl_link_ops_get(kind);
if (ops)
goto replay;
}
#endif
NL_SET_ERR_MSG(extack, "Unknown device type");
return -EOPNOTSUPP;
if (kind[0]) {
__rtnl_unlock();
request_module("rtnl-link-%s", kind);
rtnl_lock();
ops = rtnl_link_ops_get(kind);
if (ops)
goto replay;
}
#endif
NL_SET_ERR_MSG(extack, "Unknown device type");
return -EOPNOTSUPP;
}

if (!ops->setup)
return -EOPNOTSUPP;

if (!ifname[0]) {
snprintf(ifname, IFNAMSIZ, "%s%%d", ops->kind);
name_assign_type = NET_NAME_ENUM;
}
if (!ops->setup)
return -EOPNOTSUPP;

dest_net = rtnl_link_get_net_capable(skb, net, tb, CAP_NET_ADMIN);
if (IS_ERR(dest_net))
return PTR_ERR(dest_net);
if (!ifname[0]) {
snprintf(ifname, IFNAMSIZ, "%s%%d", ops->kind);
name_assign_type = NET_NAME_ENUM;
}

if (tb[IFLA_LINK_NETNSID]) {
int id = nla_get_s32(tb[IFLA_LINK_NETNSID]);
dest_net = rtnl_link_get_net_capable(skb, net, tb, CAP_NET_ADMIN);
if (IS_ERR(dest_net))
return PTR_ERR(dest_net);

link_net = get_net_ns_by_id(dest_net, id);
if (!link_net) {
NL_SET_ERR_MSG(extack, "Unknown network namespace id");
err = -EINVAL;
goto out;
}
err = -EPERM;
if (!netlink_ns_capable(skb, link_net->user_ns, CAP_NET_ADMIN))
goto out;
}
if (tb[IFLA_LINK_NETNSID]) {
int id = nla_get_s32(tb[IFLA_LINK_NETNSID]);

dev = rtnl_create_link(link_net ? : dest_net, ifname,
name_assign_type, ops, tb, extack);
if (IS_ERR(dev)) {
err = PTR_ERR(dev);
link_net = get_net_ns_by_id(dest_net, id);
if (!link_net) {
NL_SET_ERR_MSG(extack, "Unknown network namespace id");
err = -EINVAL;
goto out;
}
err = -EPERM;
if (!netlink_ns_capable(skb, link_net->user_ns, CAP_NET_ADMIN))
goto out;
} else {
link_net = NULL;
}

dev->ifindex = ifm->ifi_index;
dev = rtnl_create_link(link_net ? : dest_net, ifname,
name_assign_type, ops, tb, extack);
if (IS_ERR(dev)) {
err = PTR_ERR(dev);
goto out;
}

if (ops->newlink) {
err = ops->newlink(link_net ? : net, dev, tb, data,
extack);
/* Drivers should call free_netdev() in ->destructor
* and unregister it on failure after registration
* so that device could be finally freed in rtnl_unlock.
*/
if (err < 0) {
/* If device is not registered at all, free it now */
if (dev->reg_state == NETREG_UNINITIALIZED)
free_netdev(dev);
goto out;
}
} else {
err = register_netdevice(dev);
if (err < 0) {
dev->ifindex = ifm->ifi_index;

if (ops->newlink) {
err = ops->newlink(link_net ? : net, dev, tb, data, extack);
/* Drivers should call free_netdev() in ->destructor
* and unregister it on failure after registration
* so that device could be finally freed in rtnl_unlock.
*/
if (err < 0) {
/* If device is not registered at all, free it now */
if (dev->reg_state == NETREG_UNINITIALIZED)
free_netdev(dev);
goto out;
}
goto out;
}
} else {
err = register_netdevice(dev);
if (err < 0) {
free_netdev(dev);
goto out;
}
err = rtnl_configure_link(dev, ifm);
}
err = rtnl_configure_link(dev, ifm);
if (err < 0)
goto out_unregister;
if (link_net) {
err = dev_change_net_namespace(dev, dest_net, ifname);
if (err < 0)
goto out_unregister;
if (link_net) {
err = dev_change_net_namespace(dev, dest_net, ifname);
if (err < 0)
goto out_unregister;
}
if (tb[IFLA_MASTER]) {
err = do_set_master(dev, nla_get_u32(tb[IFLA_MASTER]),
extack);
if (err)
goto out_unregister;
}
}
if (tb[IFLA_MASTER]) {
err = do_set_master(dev, nla_get_u32(tb[IFLA_MASTER]), extack);
if (err)
goto out_unregister;
}
out:
if (link_net)
put_net(link_net);
put_net(dest_net);
return err;
if (link_net)
put_net(link_net);
put_net(dest_net);
return err;
out_unregister:
if (ops->newlink) {
LIST_HEAD(list_kill);
if (ops->newlink) {
LIST_HEAD(list_kill);

ops->dellink(dev, &list_kill);
unregister_netdevice_many(&list_kill);
} else {
unregister_netdevice(dev);
}
goto out;
ops->dellink(dev, &list_kill);
unregister_netdevice_many(&list_kill);
} else {
unregister_netdevice(dev);
}
goto out;
}

static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct nlattr **attr;
int ret;

attr = kmalloc_array(RTNL_MAX_TYPE + 1, sizeof(*attr), GFP_KERNEL);
if (!attr)
return -ENOMEM;

ret = __rtnl_newlink(skb, nlh, attr, extack);
kfree(attr);
return ret;
}

static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr *nlh,
Expand Down

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