Currently netlink users BUG when the allocated skb for an event notification is undersized. While this is certainly a kernel bug, its not critical and crashing the kernel is too drastic, especially when considering that these errors have appeared multiple times in the past and it BUGs even if no listeners are present. This patch replaces BUG by WARN_ON and changes the notification functions to inform potential listeners of undersized allocations using a unique error code (EMSGSIZE). Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
196 lines
4.8 KiB
C
196 lines
4.8 KiB
C
/*
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* Bridge netlink control interface
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*
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* Authors:
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* Stephen Hemminger <shemminger@osdl.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/rtnetlink.h>
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#include <net/netlink.h>
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#include "br_private.h"
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static inline size_t br_nlmsg_size(void)
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{
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return NLMSG_ALIGN(sizeof(struct ifinfomsg))
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+ nla_total_size(IFNAMSIZ) /* IFLA_IFNAME */
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+ nla_total_size(MAX_ADDR_LEN) /* IFLA_ADDRESS */
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+ nla_total_size(4) /* IFLA_MASTER */
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+ nla_total_size(4) /* IFLA_MTU */
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+ nla_total_size(4) /* IFLA_LINK */
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+ nla_total_size(1) /* IFLA_OPERSTATE */
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+ nla_total_size(1); /* IFLA_PROTINFO */
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}
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/*
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* Create one netlink message for one interface
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* Contains port and master info as well as carrier and bridge state.
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*/
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static int br_fill_ifinfo(struct sk_buff *skb, const struct net_bridge_port *port,
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u32 pid, u32 seq, int event, unsigned int flags)
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{
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const struct net_bridge *br = port->br;
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const struct net_device *dev = port->dev;
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struct ifinfomsg *hdr;
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struct nlmsghdr *nlh;
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u8 operstate = netif_running(dev) ? dev->operstate : IF_OPER_DOWN;
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pr_debug("br_fill_info event %d port %s master %s\n",
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event, dev->name, br->dev->name);
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nlh = nlmsg_put(skb, pid, seq, event, sizeof(*hdr), flags);
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if (nlh == NULL)
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return -EMSGSIZE;
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hdr = nlmsg_data(nlh);
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hdr->ifi_family = AF_BRIDGE;
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hdr->__ifi_pad = 0;
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hdr->ifi_type = dev->type;
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hdr->ifi_index = dev->ifindex;
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hdr->ifi_flags = dev_get_flags(dev);
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hdr->ifi_change = 0;
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NLA_PUT_STRING(skb, IFLA_IFNAME, dev->name);
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NLA_PUT_U32(skb, IFLA_MASTER, br->dev->ifindex);
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NLA_PUT_U32(skb, IFLA_MTU, dev->mtu);
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NLA_PUT_U8(skb, IFLA_OPERSTATE, operstate);
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if (dev->addr_len)
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NLA_PUT(skb, IFLA_ADDRESS, dev->addr_len, dev->dev_addr);
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if (dev->ifindex != dev->iflink)
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NLA_PUT_U32(skb, IFLA_LINK, dev->iflink);
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if (event == RTM_NEWLINK)
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NLA_PUT_U8(skb, IFLA_PROTINFO, port->state);
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return nlmsg_end(skb, nlh);
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nla_put_failure:
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nlmsg_cancel(skb, nlh);
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return -EMSGSIZE;
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}
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/*
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* Notify listeners of a change in port information
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*/
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void br_ifinfo_notify(int event, struct net_bridge_port *port)
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{
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struct sk_buff *skb;
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int err = -ENOBUFS;
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pr_debug("bridge notify event=%d\n", event);
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skb = nlmsg_new(br_nlmsg_size(), GFP_ATOMIC);
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if (skb == NULL)
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goto errout;
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err = br_fill_ifinfo(skb, port, 0, 0, event, 0);
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if (err < 0) {
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/* -EMSGSIZE implies BUG in br_nlmsg_size() */
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WARN_ON(err == -EMSGSIZE);
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kfree_skb(skb);
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goto errout;
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}
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err = rtnl_notify(skb, 0, RTNLGRP_LINK, NULL, GFP_ATOMIC);
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errout:
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if (err < 0)
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rtnl_set_sk_err(RTNLGRP_LINK, err);
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}
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/*
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* Dump information about all ports, in response to GETLINK
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*/
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static int br_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
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{
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struct net_device *dev;
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int idx;
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read_lock(&dev_base_lock);
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for (dev = dev_base, idx = 0; dev; dev = dev->next) {
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/* not a bridge port */
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if (dev->br_port == NULL || idx < cb->args[0])
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goto skip;
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if (br_fill_ifinfo(skb, dev->br_port, NETLINK_CB(cb->skb).pid,
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cb->nlh->nlmsg_seq, RTM_NEWLINK,
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NLM_F_MULTI) < 0)
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break;
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skip:
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++idx;
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}
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read_unlock(&dev_base_lock);
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cb->args[0] = idx;
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return skb->len;
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}
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/*
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* Change state of port (ie from forwarding to blocking etc)
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* Used by spanning tree in user space.
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*/
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static int br_rtm_setlink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
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{
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struct ifinfomsg *ifm;
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struct nlattr *protinfo;
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struct net_device *dev;
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struct net_bridge_port *p;
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u8 new_state;
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if (nlmsg_len(nlh) < sizeof(*ifm))
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return -EINVAL;
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ifm = nlmsg_data(nlh);
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if (ifm->ifi_family != AF_BRIDGE)
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return -EPFNOSUPPORT;
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protinfo = nlmsg_find_attr(nlh, sizeof(*ifm), IFLA_PROTINFO);
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if (!protinfo || nla_len(protinfo) < sizeof(u8))
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return -EINVAL;
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new_state = nla_get_u8(protinfo);
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if (new_state > BR_STATE_BLOCKING)
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return -EINVAL;
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dev = __dev_get_by_index(ifm->ifi_index);
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if (!dev)
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return -ENODEV;
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p = dev->br_port;
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if (!p)
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return -EINVAL;
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/* if kernel STP is running, don't allow changes */
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if (p->br->stp_enabled)
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return -EBUSY;
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if (!netif_running(dev) ||
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(!netif_carrier_ok(dev) && new_state != BR_STATE_DISABLED))
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return -ENETDOWN;
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p->state = new_state;
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br_log_state(p);
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return 0;
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}
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static struct rtnetlink_link bridge_rtnetlink_table[RTM_NR_MSGTYPES] = {
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[RTM_GETLINK - RTM_BASE] = { .dumpit = br_dump_ifinfo, },
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[RTM_SETLINK - RTM_BASE] = { .doit = br_rtm_setlink, },
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};
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void __init br_netlink_init(void)
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{
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rtnetlink_links[PF_BRIDGE] = bridge_rtnetlink_table;
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}
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void __exit br_netlink_fini(void)
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{
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rtnetlink_links[PF_BRIDGE] = NULL;
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}
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