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![Colin Ian King](/assets/img/avatar_default.png)
A recent change added a null check on p->dev after p->dev was being
dereferenced by the ns_capable check on p->dev. It turns out that
neither the p->dev and p->br null checks are necessary, and can be
removed, which cleans up a static analyis warning.
As Nikolay Aleksandrov noted, these checks can be removed because:
"My reasoning of why it shouldn't be possible:
- On port add new_nbp() sets both p->dev and p->br before creating
kobj/sysfs
- On port del (trickier) del_nbp() calls kobject_del() before call_rcu()
to destroy the port which in turn calls sysfs_remove_dir() which uses
kernfs_remove() which deactivates (shouldn't be able to open new
files) and calls kernfs_drain() to drain current open/mmaped files in
the respective dir before continuing, thus making it impossible to
open a bridge port sysfs file with p->dev and p->br equal to NULL.
So I think it's safe to remove those checks altogether. It'd be nice to
get a second look over my reasoning as I might be missing something in
sysfs/kernfs call path."
Thanks to Nikolay Aleksandrov's suggestion to remove the check and
David Miller for sanity checking this.
Detected by CoverityScan, CID#751490 ("Dereference before null check")
Fixes: a5f3ea54f3
("net: bridge: add support for raw sysfs port options")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
406 lines
10 KiB
C
406 lines
10 KiB
C
/*
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* Sysfs attributes of bridge ports
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* Linux ethernet bridge
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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/capability.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/if_bridge.h>
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#include <linux/rtnetlink.h>
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#include <linux/spinlock.h>
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#include <linux/sched/signal.h>
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#include "br_private.h"
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struct brport_attribute {
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struct attribute attr;
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ssize_t (*show)(struct net_bridge_port *, char *);
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int (*store)(struct net_bridge_port *, unsigned long);
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int (*store_raw)(struct net_bridge_port *, char *);
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};
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#define BRPORT_ATTR_RAW(_name, _mode, _show, _store) \
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const struct brport_attribute brport_attr_##_name = { \
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.attr = {.name = __stringify(_name), \
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.mode = _mode }, \
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.show = _show, \
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.store_raw = _store, \
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};
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#define BRPORT_ATTR(_name, _mode, _show, _store) \
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const struct brport_attribute brport_attr_##_name = { \
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.attr = {.name = __stringify(_name), \
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.mode = _mode }, \
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.show = _show, \
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.store = _store, \
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};
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#define BRPORT_ATTR_FLAG(_name, _mask) \
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static ssize_t show_##_name(struct net_bridge_port *p, char *buf) \
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{ \
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return sprintf(buf, "%d\n", !!(p->flags & _mask)); \
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} \
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static int store_##_name(struct net_bridge_port *p, unsigned long v) \
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{ \
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return store_flag(p, v, _mask); \
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} \
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static BRPORT_ATTR(_name, 0644, \
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show_##_name, store_##_name)
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static int store_flag(struct net_bridge_port *p, unsigned long v,
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unsigned long mask)
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{
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unsigned long flags;
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flags = p->flags;
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if (v)
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flags |= mask;
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else
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flags &= ~mask;
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if (flags != p->flags) {
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p->flags = flags;
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br_port_flags_change(p, mask);
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}
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return 0;
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}
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static ssize_t show_path_cost(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%d\n", p->path_cost);
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}
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static BRPORT_ATTR(path_cost, 0644,
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show_path_cost, br_stp_set_path_cost);
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static ssize_t show_priority(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%d\n", p->priority);
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}
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static BRPORT_ATTR(priority, 0644,
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show_priority, br_stp_set_port_priority);
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static ssize_t show_designated_root(struct net_bridge_port *p, char *buf)
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{
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return br_show_bridge_id(buf, &p->designated_root);
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}
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static BRPORT_ATTR(designated_root, 0444, show_designated_root, NULL);
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static ssize_t show_designated_bridge(struct net_bridge_port *p, char *buf)
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{
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return br_show_bridge_id(buf, &p->designated_bridge);
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}
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static BRPORT_ATTR(designated_bridge, 0444, show_designated_bridge, NULL);
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static ssize_t show_designated_port(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%d\n", p->designated_port);
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}
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static BRPORT_ATTR(designated_port, 0444, show_designated_port, NULL);
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static ssize_t show_designated_cost(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%d\n", p->designated_cost);
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}
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static BRPORT_ATTR(designated_cost, 0444, show_designated_cost, NULL);
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static ssize_t show_port_id(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "0x%x\n", p->port_id);
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}
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static BRPORT_ATTR(port_id, 0444, show_port_id, NULL);
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static ssize_t show_port_no(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "0x%x\n", p->port_no);
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}
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static BRPORT_ATTR(port_no, 0444, show_port_no, NULL);
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static ssize_t show_change_ack(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%d\n", p->topology_change_ack);
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}
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static BRPORT_ATTR(change_ack, 0444, show_change_ack, NULL);
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static ssize_t show_config_pending(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%d\n", p->config_pending);
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}
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static BRPORT_ATTR(config_pending, 0444, show_config_pending, NULL);
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static ssize_t show_port_state(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%d\n", p->state);
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}
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static BRPORT_ATTR(state, 0444, show_port_state, NULL);
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static ssize_t show_message_age_timer(struct net_bridge_port *p,
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char *buf)
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{
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return sprintf(buf, "%ld\n", br_timer_value(&p->message_age_timer));
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}
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static BRPORT_ATTR(message_age_timer, 0444, show_message_age_timer, NULL);
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static ssize_t show_forward_delay_timer(struct net_bridge_port *p,
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char *buf)
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{
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return sprintf(buf, "%ld\n", br_timer_value(&p->forward_delay_timer));
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}
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static BRPORT_ATTR(forward_delay_timer, 0444, show_forward_delay_timer, NULL);
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static ssize_t show_hold_timer(struct net_bridge_port *p,
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char *buf)
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{
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return sprintf(buf, "%ld\n", br_timer_value(&p->hold_timer));
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}
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static BRPORT_ATTR(hold_timer, 0444, show_hold_timer, NULL);
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static int store_flush(struct net_bridge_port *p, unsigned long v)
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{
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br_fdb_delete_by_port(p->br, p, 0, 0); // Don't delete local entry
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return 0;
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}
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static BRPORT_ATTR(flush, 0200, NULL, store_flush);
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static ssize_t show_group_fwd_mask(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%#x\n", p->group_fwd_mask);
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}
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static int store_group_fwd_mask(struct net_bridge_port *p,
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unsigned long v)
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{
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if (v & BR_GROUPFWD_MACPAUSE)
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return -EINVAL;
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p->group_fwd_mask = v;
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return 0;
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}
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static BRPORT_ATTR(group_fwd_mask, 0644, show_group_fwd_mask,
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store_group_fwd_mask);
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static ssize_t show_backup_port(struct net_bridge_port *p, char *buf)
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{
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struct net_bridge_port *backup_p;
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int ret = 0;
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rcu_read_lock();
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backup_p = rcu_dereference(p->backup_port);
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if (backup_p)
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ret = sprintf(buf, "%s\n", backup_p->dev->name);
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rcu_read_unlock();
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return ret;
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}
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static int store_backup_port(struct net_bridge_port *p, char *buf)
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{
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struct net_device *backup_dev = NULL;
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char *nl = strchr(buf, '\n');
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if (nl)
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*nl = '\0';
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if (strlen(buf) > 0) {
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backup_dev = __dev_get_by_name(dev_net(p->dev), buf);
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if (!backup_dev)
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return -ENOENT;
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}
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return nbp_backup_change(p, backup_dev);
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}
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static BRPORT_ATTR_RAW(backup_port, 0644, show_backup_port, store_backup_port);
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BRPORT_ATTR_FLAG(hairpin_mode, BR_HAIRPIN_MODE);
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BRPORT_ATTR_FLAG(bpdu_guard, BR_BPDU_GUARD);
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BRPORT_ATTR_FLAG(root_block, BR_ROOT_BLOCK);
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BRPORT_ATTR_FLAG(learning, BR_LEARNING);
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BRPORT_ATTR_FLAG(unicast_flood, BR_FLOOD);
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BRPORT_ATTR_FLAG(proxyarp, BR_PROXYARP);
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BRPORT_ATTR_FLAG(proxyarp_wifi, BR_PROXYARP_WIFI);
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BRPORT_ATTR_FLAG(multicast_flood, BR_MCAST_FLOOD);
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BRPORT_ATTR_FLAG(broadcast_flood, BR_BCAST_FLOOD);
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BRPORT_ATTR_FLAG(neigh_suppress, BR_NEIGH_SUPPRESS);
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BRPORT_ATTR_FLAG(isolated, BR_ISOLATED);
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#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
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static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
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{
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return sprintf(buf, "%d\n", p->multicast_router);
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}
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static int store_multicast_router(struct net_bridge_port *p,
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unsigned long v)
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{
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return br_multicast_set_port_router(p, v);
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}
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static BRPORT_ATTR(multicast_router, 0644, show_multicast_router,
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store_multicast_router);
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BRPORT_ATTR_FLAG(multicast_fast_leave, BR_MULTICAST_FAST_LEAVE);
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BRPORT_ATTR_FLAG(multicast_to_unicast, BR_MULTICAST_TO_UNICAST);
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#endif
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static const struct brport_attribute *brport_attrs[] = {
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&brport_attr_path_cost,
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&brport_attr_priority,
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&brport_attr_port_id,
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&brport_attr_port_no,
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&brport_attr_designated_root,
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&brport_attr_designated_bridge,
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&brport_attr_designated_port,
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&brport_attr_designated_cost,
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&brport_attr_state,
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&brport_attr_change_ack,
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&brport_attr_config_pending,
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&brport_attr_message_age_timer,
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&brport_attr_forward_delay_timer,
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&brport_attr_hold_timer,
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&brport_attr_flush,
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&brport_attr_hairpin_mode,
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&brport_attr_bpdu_guard,
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&brport_attr_root_block,
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&brport_attr_learning,
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&brport_attr_unicast_flood,
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#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
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&brport_attr_multicast_router,
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&brport_attr_multicast_fast_leave,
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&brport_attr_multicast_to_unicast,
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#endif
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&brport_attr_proxyarp,
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&brport_attr_proxyarp_wifi,
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&brport_attr_multicast_flood,
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&brport_attr_broadcast_flood,
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&brport_attr_group_fwd_mask,
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&brport_attr_neigh_suppress,
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&brport_attr_isolated,
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&brport_attr_backup_port,
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NULL
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};
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#define to_brport_attr(_at) container_of(_at, struct brport_attribute, attr)
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static ssize_t brport_show(struct kobject *kobj,
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struct attribute *attr, char *buf)
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{
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struct brport_attribute *brport_attr = to_brport_attr(attr);
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struct net_bridge_port *p = kobj_to_brport(kobj);
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if (!brport_attr->show)
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return -EINVAL;
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return brport_attr->show(p, buf);
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}
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static ssize_t brport_store(struct kobject *kobj,
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struct attribute *attr,
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const char *buf, size_t count)
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{
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struct brport_attribute *brport_attr = to_brport_attr(attr);
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struct net_bridge_port *p = kobj_to_brport(kobj);
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ssize_t ret = -EINVAL;
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unsigned long val;
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char *endp;
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if (!ns_capable(dev_net(p->dev)->user_ns, CAP_NET_ADMIN))
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return -EPERM;
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if (!rtnl_trylock())
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return restart_syscall();
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if (brport_attr->store_raw) {
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char *buf_copy;
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buf_copy = kstrndup(buf, count, GFP_KERNEL);
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if (!buf_copy) {
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ret = -ENOMEM;
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goto out_unlock;
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}
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spin_lock_bh(&p->br->lock);
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ret = brport_attr->store_raw(p, buf_copy);
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spin_unlock_bh(&p->br->lock);
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kfree(buf_copy);
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} else if (brport_attr->store) {
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val = simple_strtoul(buf, &endp, 0);
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if (endp == buf)
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goto out_unlock;
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spin_lock_bh(&p->br->lock);
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ret = brport_attr->store(p, val);
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spin_unlock_bh(&p->br->lock);
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}
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if (!ret) {
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br_ifinfo_notify(RTM_NEWLINK, NULL, p);
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ret = count;
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}
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out_unlock:
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rtnl_unlock();
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return ret;
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}
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const struct sysfs_ops brport_sysfs_ops = {
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.show = brport_show,
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.store = brport_store,
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};
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/*
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* Add sysfs entries to ethernet device added to a bridge.
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* Creates a brport subdirectory with bridge attributes.
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* Puts symlink in bridge's brif subdirectory
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*/
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int br_sysfs_addif(struct net_bridge_port *p)
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{
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struct net_bridge *br = p->br;
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const struct brport_attribute **a;
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int err;
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err = sysfs_create_link(&p->kobj, &br->dev->dev.kobj,
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SYSFS_BRIDGE_PORT_LINK);
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if (err)
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return err;
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for (a = brport_attrs; *a; ++a) {
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err = sysfs_create_file(&p->kobj, &((*a)->attr));
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if (err)
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return err;
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}
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strlcpy(p->sysfs_name, p->dev->name, IFNAMSIZ);
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return sysfs_create_link(br->ifobj, &p->kobj, p->sysfs_name);
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}
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/* Rename bridge's brif symlink */
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int br_sysfs_renameif(struct net_bridge_port *p)
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{
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struct net_bridge *br = p->br;
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int err;
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/* If a rename fails, the rollback will cause another
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* rename call with the existing name.
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*/
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if (!strncmp(p->sysfs_name, p->dev->name, IFNAMSIZ))
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return 0;
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err = sysfs_rename_link(br->ifobj, &p->kobj,
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p->sysfs_name, p->dev->name);
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if (err)
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netdev_notice(br->dev, "unable to rename link %s to %s",
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p->sysfs_name, p->dev->name);
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else
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strlcpy(p->sysfs_name, p->dev->name, IFNAMSIZ);
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return err;
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}
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