root/net/bridge/br_ioctl.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      Ioctl handler
 *      Linux ethernet bridge
 *
 *      Authors:
 *      Lennert Buytenhek               <buytenh@gnu.org>
 */

#include <linux/capability.h>
#include <linux/compat.h>
#include <linux/kernel.h>
#include <linux/if_bridge.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/times.h>
#include <net/net_namespace.h>
#include <linux/uaccess.h>
#include "br_private.h"

static int get_bridge_ifindices(struct net *net, int *indices, int num)
{
        struct net_device *dev;
        int i = 0;

        rcu_read_lock();
        for_each_netdev_rcu(net, dev) {
                if (i >= num)
                        break;
                if (netif_is_bridge_master(dev))
                        indices[i++] = dev->ifindex;
        }
        rcu_read_unlock();

        return i;
}

/* called with RTNL */
static void get_port_ifindices(struct net_bridge *br, int *ifindices, int num)
{
        struct net_bridge_port *p;

        list_for_each_entry(p, &br->port_list, list) {
                if (p->port_no < num)
                        ifindices[p->port_no] = p->dev->ifindex;
        }
}

/*
 * Format up to a page worth of forwarding table entries
 * userbuf -- where to copy result
 * maxnum  -- maximum number of entries desired
 *            (limited to a page for sanity)
 * offset  -- number of records to skip
 */
static int get_fdb_entries(struct net_bridge *br, void __user *userbuf,
                           unsigned long maxnum, unsigned long offset)
{
        int num;
        void *buf;
        size_t size;

        /* Clamp size to PAGE_SIZE, test maxnum to avoid overflow */
        if (maxnum > PAGE_SIZE/sizeof(struct __fdb_entry))
                maxnum = PAGE_SIZE/sizeof(struct __fdb_entry);

        size = maxnum * sizeof(struct __fdb_entry);

        buf = kmalloc(size, GFP_USER);
        if (!buf)
                return -ENOMEM;

        num = br_fdb_fillbuf(br, buf, maxnum, offset);
        if (num > 0) {
                if (copy_to_user(userbuf, buf,
                                 array_size(num, sizeof(struct __fdb_entry))))
                        num = -EFAULT;
        }
        kfree(buf);

        return num;
}

/* called with RTNL */
static int add_del_if(struct net_bridge *br, int ifindex, int isadd)
{
        struct net *net = dev_net(br->dev);
        struct net_device *dev;
        int ret;

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;

        dev = __dev_get_by_index(net, ifindex);
        if (dev == NULL)
                return -EINVAL;

        if (isadd)
                ret = br_add_if(br, dev, NULL);
        else
                ret = br_del_if(br, dev);

        return ret;
}

#define BR_UARGS_MAX 4
static int br_dev_read_uargs(unsigned long *args, size_t nr_args,
                             void __user **argp, void __user *data)
{
        int ret;

        if (nr_args < 2 || nr_args > BR_UARGS_MAX)
                return -EINVAL;

        if (in_compat_syscall()) {
                unsigned int cargs[BR_UARGS_MAX];
                int i;

                ret = copy_from_user(cargs, data, nr_args * sizeof(*cargs));
                if (ret)
                        goto fault;

                for (i = 0; i < nr_args; ++i)
                        args[i] = cargs[i];

                *argp = compat_ptr(args[1]);
        } else {
                ret = copy_from_user(args, data, nr_args * sizeof(*args));
                if (ret)
                        goto fault;
                *argp = (void __user *)args[1];
        }

        return 0;
fault:
        return -EFAULT;
}

/*
 * Legacy ioctl's through SIOCDEVPRIVATE
 * This interface is deprecated because it was too difficult
 * to do the translation for 32/64bit ioctl compatibility.
 */
int br_dev_siocdevprivate(struct net_device *dev, struct ifreq *rq,
                          void __user *data, int cmd)
{
        struct net_bridge *br = netdev_priv(dev);
        struct net_bridge_port *p = NULL;
        unsigned long args[4];
        void __user *argp;
        int ret;

        ret = br_dev_read_uargs(args, ARRAY_SIZE(args), &argp, data);
        if (ret)
                return ret;

        switch (args[0]) {
        case BRCTL_ADD_IF:
        case BRCTL_DEL_IF:
                return add_del_if(br, args[1], args[0] == BRCTL_ADD_IF);

        case BRCTL_GET_BRIDGE_INFO:
        {
                struct __bridge_info b;

                memset(&b, 0, sizeof(struct __bridge_info));
                rcu_read_lock();
                memcpy(&b.designated_root, &br->designated_root, 8);
                memcpy(&b.bridge_id, &br->bridge_id, 8);
                b.root_path_cost = br->root_path_cost;
                b.max_age = jiffies_to_clock_t(br->max_age);
                b.hello_time = jiffies_to_clock_t(br->hello_time);
                b.forward_delay = br->forward_delay;
                b.bridge_max_age = br->bridge_max_age;
                b.bridge_hello_time = br->bridge_hello_time;
                b.bridge_forward_delay = jiffies_to_clock_t(br->bridge_forward_delay);
                b.topology_change = br->topology_change;
                b.topology_change_detected = br->topology_change_detected;
                b.root_port = br->root_port;

                b.stp_enabled = (br->stp_enabled != BR_NO_STP);
                b.ageing_time = jiffies_to_clock_t(br->ageing_time);
                b.hello_timer_value = br_timer_value(&br->hello_timer);
                b.tcn_timer_value = br_timer_value(&br->tcn_timer);
                b.topology_change_timer_value = br_timer_value(&br->topology_change_timer);
                b.gc_timer_value = br_timer_value(&br->gc_work.timer);
                rcu_read_unlock();

                if (copy_to_user((void __user *)args[1], &b, sizeof(b)))
                        return -EFAULT;

                return 0;
        }

        case BRCTL_GET_PORT_LIST:
        {
                int num, *indices;

                num = args[2];
                if (num < 0)
                        return -EINVAL;
                if (num == 0)
                        num = 256;
                if (num > BR_MAX_PORTS)
                        num = BR_MAX_PORTS;

                indices = kzalloc_objs(int, num);
                if (indices == NULL)
                        return -ENOMEM;

                get_port_ifindices(br, indices, num);
                if (copy_to_user(argp, indices, array_size(num, sizeof(int))))
                        num =  -EFAULT;
                kfree(indices);
                return num;
        }

        case BRCTL_SET_BRIDGE_FORWARD_DELAY:
                if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                ret = br_set_forward_delay(br, args[1]);
                break;

        case BRCTL_SET_BRIDGE_HELLO_TIME:
                if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                ret = br_set_hello_time(br, args[1]);
                break;

        case BRCTL_SET_BRIDGE_MAX_AGE:
                if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                ret = br_set_max_age(br, args[1]);
                break;

        case BRCTL_SET_AGEING_TIME:
                if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                ret = br_set_ageing_time(br, args[1]);
                break;

        case BRCTL_GET_PORT_INFO:
        {
                struct __port_info p;
                struct net_bridge_port *pt;

                rcu_read_lock();
                if ((pt = br_get_port(br, args[2])) == NULL) {
                        rcu_read_unlock();
                        return -EINVAL;
                }

                memset(&p, 0, sizeof(struct __port_info));
                memcpy(&p.designated_root, &pt->designated_root, 8);
                memcpy(&p.designated_bridge, &pt->designated_bridge, 8);
                p.port_id = pt->port_id;
                p.designated_port = pt->designated_port;
                p.path_cost = pt->path_cost;
                p.designated_cost = pt->designated_cost;
                p.state = pt->state;
                p.top_change_ack = pt->topology_change_ack;
                p.config_pending = pt->config_pending;
                p.message_age_timer_value = br_timer_value(&pt->message_age_timer);
                p.forward_delay_timer_value = br_timer_value(&pt->forward_delay_timer);
                p.hold_timer_value = br_timer_value(&pt->hold_timer);

                rcu_read_unlock();

                if (copy_to_user(argp, &p, sizeof(p)))
                        return -EFAULT;

                return 0;
        }

        case BRCTL_SET_BRIDGE_STP_STATE:
                if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                ret = br_stp_set_enabled(br, args[1], NULL);
                break;

        case BRCTL_SET_BRIDGE_PRIORITY:
                if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                br_stp_set_bridge_priority(br, args[1]);
                ret = 0;
                break;

        case BRCTL_SET_PORT_PRIORITY:
        {
                if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                spin_lock_bh(&br->lock);
                if ((p = br_get_port(br, args[1])) == NULL)
                        ret = -EINVAL;
                else
                        ret = br_stp_set_port_priority(p, args[2]);
                spin_unlock_bh(&br->lock);
                break;
        }

        case BRCTL_SET_PATH_COST:
        {
                if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                spin_lock_bh(&br->lock);
                if ((p = br_get_port(br, args[1])) == NULL)
                        ret = -EINVAL;
                else
                        ret = br_stp_set_path_cost(p, args[2]);
                spin_unlock_bh(&br->lock);
                break;
        }

        case BRCTL_GET_FDB_ENTRIES:
                return get_fdb_entries(br, argp, args[2], args[3]);

        default:
                ret = -EOPNOTSUPP;
        }

        if (!ret) {
                if (p)
                        br_ifinfo_notify(RTM_NEWLINK, NULL, p);
                else
                        netdev_state_change(br->dev);
        }

        return ret;
}

static int old_deviceless(struct net *net, void __user *data)
{
        unsigned long args[3];
        void __user *argp;
        int ret;

        ret = br_dev_read_uargs(args, ARRAY_SIZE(args), &argp, data);
        if (ret)
                return ret;

        switch (args[0]) {
        case BRCTL_GET_VERSION:
                return BRCTL_VERSION;

        case BRCTL_GET_BRIDGES:
        {
                int *indices;
                int ret = 0;

                if (args[2] >= 2048)
                        return -ENOMEM;
                indices = kzalloc_objs(int, args[2]);
                if (indices == NULL)
                        return -ENOMEM;

                args[2] = get_bridge_ifindices(net, indices, args[2]);

                ret = copy_to_user(argp, indices,
                                   array_size(args[2], sizeof(int)))
                        ? -EFAULT : args[2];

                kfree(indices);
                return ret;
        }

        case BRCTL_ADD_BRIDGE:
        case BRCTL_DEL_BRIDGE:
        {
                char buf[IFNAMSIZ];

                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                if (copy_from_user(buf, argp, IFNAMSIZ))
                        return -EFAULT;

                buf[IFNAMSIZ-1] = 0;

                if (args[0] == BRCTL_ADD_BRIDGE)
                        return br_add_bridge(net, buf);

                return br_del_bridge(net, buf);
        }
        }

        return -EOPNOTSUPP;
}

int br_ioctl_stub(struct net *net, unsigned int cmd, void __user *uarg)
{
        int ret = -EOPNOTSUPP;
        struct ifreq ifr;

        if (cmd == SIOCBRADDIF || cmd == SIOCBRDELIF) {
                void __user *data;
                char *colon;

                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        return -EPERM;

                if (get_user_ifreq(&ifr, &data, uarg))
                        return -EFAULT;

                ifr.ifr_name[IFNAMSIZ - 1] = 0;
                colon = strchr(ifr.ifr_name, ':');
                if (colon)
                        *colon = 0;
        }

        rtnl_lock();

        switch (cmd) {
        case SIOCGIFBR:
        case SIOCSIFBR:
                ret = old_deviceless(net, uarg);
                break;
        case SIOCBRADDBR:
        case SIOCBRDELBR:
        {
                char buf[IFNAMSIZ];

                if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) {
                        ret = -EPERM;
                        break;
                }

                if (copy_from_user(buf, uarg, IFNAMSIZ)) {
                        ret = -EFAULT;
                        break;
                }

                buf[IFNAMSIZ-1] = 0;
                if (cmd == SIOCBRADDBR)
                        ret = br_add_bridge(net, buf);
                else
                        ret = br_del_bridge(net, buf);
        }
                break;
        case SIOCBRADDIF:
        case SIOCBRDELIF:
        {
                struct net_device *dev;

                dev = __dev_get_by_name(net, ifr.ifr_name);
                if (!dev || !netif_device_present(dev)) {
                        ret = -ENODEV;
                        break;
                }
                if (!netif_is_bridge_master(dev)) {
                        ret = -EOPNOTSUPP;
                        break;
                }

                ret = add_del_if(netdev_priv(dev), ifr.ifr_ifindex, cmd == SIOCBRADDIF);
        }
                break;
        }

        rtnl_unlock();

        return ret;
}