From 420d031822737ef570df6834c0eae26f33988f20 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 27 Nov 2018 22:32:30 -0800 Subject: [PATCH 1/2] rtnetlink: remove a level of indentation in rtnl_newlink() rtnl_newlink() used to create VLAs based on link kind. Since commit ccf8dbcd062a ("rtnetlink: Remove VLA usage") statically sized array is created on the stack, so there is no more use for a separate code block that used to be the VLA's live range. While at it christmas tree the variables. Note that there is a goto-based retry so to be on the safe side the variables can no longer be initialized in place. It doesn't seem to matter, logically, but why make the code harder to read.. Signed-off-by: Jakub Kicinski Reviewed-by: David Ahern Signed-off-by: David S. Miller --- net/core/rtnetlink.c | 337 +++++++++++++++++++++---------------------- 1 file changed, 166 insertions(+), 171 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index a498bb41c9aa..ee2caa2fd940 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -2974,17 +2974,22 @@ static int rtnl_group_changelink(const struct sk_buff *skb, static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, 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 nlattr *attr[RTNL_MAX_TYPE + 1]; + 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 net_device *dev; - struct net_device *master_dev = NULL; - struct ifinfomsg *ifm; + 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 ifinfomsg *ifm; 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 @@ -3040,195 +3045,185 @@ 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; + data = NULL; + if (ops) { + if (ops->maxtype > RTNL_MAX_TYPE) + return -EINVAL; - 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 (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 (ops->validate) { + err = ops->validate(tb, data, extack); + if (err < 0) + return err; } + } - if (dev) { - int status = 0; + slave_data = NULL; + if (m_ops) { + if (m_ops->slave_maxtype > RTNL_SLAVE_MAX_TYPE) + return -EINVAL; - if (nlh->nlmsg_flags & NLM_F_EXCL) - return -EEXIST; - if (nlh->nlmsg_flags & NLM_F_REPLACE) + 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 (linkinfo[IFLA_INFO_DATA]) { + if (!ops || ops != dev->rtnl_link_ops || + !ops->changelink) return -EOPNOTSUPP; - if (linkinfo[IFLA_INFO_DATA]) { - if (!ops || ops != dev->rtnl_link_ops || - !ops->changelink) - return -EOPNOTSUPP; - - err = ops->changelink(dev, tb, 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; - - err = m_ops->slave_changelink(master_dev, dev, - tb, slave_data, - extack); - if (err < 0) - return err; - status |= DO_SETLINK_NOTIFY; - } - - return do_setlink(skb, dev, ifm, extack, tb, ifname, - status); + err = ops->changelink(dev, tb, 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, + if (linkinfo[IFLA_INFO_SLAVE_DATA]) { + if (!m_ops || !m_ops->slave_changelink) + return -EOPNOTSUPP; + + err = m_ops->slave_changelink(master_dev, dev, tb, + slave_data, extack); + if (err < 0) + return err; + status |= DO_SETLINK_NOTIFY; + } + + 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; - } + 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; - } + NL_SET_ERR_MSG(extack, "Unknown device type"); + return -EOPNOTSUPP; + } - if (!ops->setup) - return -EOPNOTSUPP; + if (!ops->setup) + return -EOPNOTSUPP; - if (!ifname[0]) { - snprintf(ifname, IFNAMSIZ, "%s%%d", ops->kind); - name_assign_type = NET_NAME_ENUM; - } + if (!ifname[0]) { + snprintf(ifname, IFNAMSIZ, "%s%%d", ops->kind); + name_assign_type = NET_NAME_ENUM; + } - dest_net = rtnl_link_get_net_capable(skb, net, tb, CAP_NET_ADMIN); - if (IS_ERR(dest_net)) - return PTR_ERR(dest_net); + dest_net = rtnl_link_get_net_capable(skb, net, tb, CAP_NET_ADMIN); + if (IS_ERR(dest_net)) + return PTR_ERR(dest_net); - if (tb[IFLA_LINK_NETNSID]) { - int id = nla_get_s32(tb[IFLA_LINK_NETNSID]); + if (tb[IFLA_LINK_NETNSID]) { + int id = nla_get_s32(tb[IFLA_LINK_NETNSID]); - 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; - } - - 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; - - 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) { - free_netdev(dev); - goto out; - } - } - 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 (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; -out_unregister: - if (ops->newlink) { - LIST_HEAD(list_kill); - - ops->dellink(dev, &list_kill); - unregister_netdevice_many(&list_kill); - } else { - unregister_netdevice(dev); - } + 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; } + + 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; + } + } else { + err = register_netdevice(dev); + if (err < 0) { + free_netdev(dev); + goto out; + } + } + 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 (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; +out_unregister: + if (ops->newlink) { + LIST_HEAD(list_kill); + + ops->dellink(dev, &list_kill); + unregister_netdevice_many(&list_kill); + } else { + unregister_netdevice(dev); + } + goto out; } static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr *nlh, From a293974590cfdc2d59c559a54d62a5ecb648104b Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 27 Nov 2018 22:32:31 -0800 Subject: [PATCH 2/2] rtnetlink: avoid frame size warning in rtnl_newlink() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Standard kernel compilation produces the following warning: net/core/rtnetlink.c: In function ‘rtnl_newlink’: net/core/rtnetlink.c:3232:1: warning: the frame size of 1288 bytes is larger than 1024 bytes [-Wframe-larger-than=] } ^ This should not really be an issue, as rtnl_newlink() stack is generally quite shallow. Fix the warning by allocating attributes with kmalloc() in a wrapper and passing it down to rtnl_newlink(), avoiding complexities on error paths. Alternatively we could kmalloc() some structure within rtnl_newlink(), slave attributes look like a good candidate. In practice it adds to already rather high complexity and length of the function. Signed-off-by: Jakub Kicinski Reviewed-by: David Ahern Signed-off-by: David S. Miller --- net/core/rtnetlink.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index ee2caa2fd940..98876cd1e36c 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -2971,14 +2971,13 @@ 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 nlattr *attr[RTNL_MAX_TYPE + 1]; struct net_device *master_dev = NULL; struct net *net = sock_net(skb->sk); const struct rtnl_link_ops *ops; @@ -3226,6 +3225,21 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, 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, struct netlink_ext_ack *extack) {