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net: bridge: mcast: add and enforce query interval minimum

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As reported[1] if query interval is set too low and we have multiple
bridges or even a single bridge with multiple querier vlans configured
we can crash the machine. Add a 1 second minimum which must be enforced
by overwriting the value if set lower (i.e. without returning an error) to
avoid breaking user-space. If that happens a log message is emitted to let
the administrator know that the interval has been set to the minimum.
The issue has been present since these intervals could be user-controlled.

[1] https://lore.kernel.org/netdev/e8b9ce41-57b9-b6e2-a46a-ff9c791cf0ba@gmail.com/

Fixes: d902eee43f ("bridge: Add multicast count/interval sysfs entries")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Nikolay Aleksandrov 2021-12-27 19:21:15 +02:00 committed by Jakub Kicinski
parent fb7bc92040
commit 99b4061095
5 changed files with 22 additions and 3 deletions
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16
net/bridge/br_multicast.c
View File

@ -4522,6 +4522,22 @@ int br_multicast_set_mld_version(struct net_bridge_mcast *brmctx,
}
#endif
void br_multicast_set_query_intvl(struct net_bridge_mcast *brmctx,
unsigned long val)
{
unsigned long intvl_jiffies = clock_t_to_jiffies(val);
if (intvl_jiffies < BR_MULTICAST_QUERY_INTVL_MIN) {
br_info(brmctx->br,
"trying to set multicast query interval below minimum, setting to %lu (%ums)\n",
jiffies_to_clock_t(BR_MULTICAST_QUERY_INTVL_MIN),
jiffies_to_msecs(BR_MULTICAST_QUERY_INTVL_MIN));
intvl_jiffies = BR_MULTICAST_QUERY_INTVL_MIN;
}
brmctx->multicast_query_interval = intvl_jiffies;
}
/**
* br_multicast_list_adjacent - Returns snooped multicast addresses
* @dev: The bridge port adjacent to which to retrieve addresses

2
net/bridge/br_netlink.c
View File

@ -1357,7 +1357,7 @@ static int br_changelink(struct net_device *brdev, struct nlattr *tb[],
if (data[IFLA_BR_MCAST_QUERY_INTVL]) {
u64 val = nla_get_u64(data[IFLA_BR_MCAST_QUERY_INTVL]);
br->multicast_ctx.multicast_query_interval = clock_t_to_jiffies(val);
br_multicast_set_query_intvl(&br->multicast_ctx, val);
}
if (data[IFLA_BR_MCAST_QUERY_RESPONSE_INTVL]) {

3
net/bridge/br_private.h
View File

@ -28,6 +28,7 @@
#define BR_MAX_PORTS (1<<BR_PORT_BITS)
#define BR_MULTICAST_DEFAULT_HASH_MAX 4096
#define BR_MULTICAST_QUERY_INTVL_MIN msecs_to_jiffies(1000)
#define BR_HWDOM_MAX BITS_PER_LONG
@ -963,6 +964,8 @@ int br_multicast_dump_querier_state(struct sk_buff *skb,
int nest_attr);
size_t br_multicast_querier_state_size(void);
size_t br_rports_size(const struct net_bridge_mcast *brmctx);
void br_multicast_set_query_intvl(struct net_bridge_mcast *brmctx,
unsigned long val);
static inline bool br_group_is_l2(const struct br_ip *group)
{

2
net/bridge/br_sysfs_br.c
View File

@ -658,7 +658,7 @@ static ssize_t multicast_query_interval_show(struct device *d,
static int set_query_interval(struct net_bridge *br, unsigned long val,
struct netlink_ext_ack *extack)
{
br->multicast_ctx.multicast_query_interval = clock_t_to_jiffies(val);
br_multicast_set_query_intvl(&br->multicast_ctx, val);
return 0;
}

2
net/bridge/br_vlan_options.c
View File

@ -521,7 +521,7 @@ static int br_vlan_process_global_one_opts(const struct net_bridge *br,
u64 val;
val = nla_get_u64(tb[BRIDGE_VLANDB_GOPTS_MCAST_QUERY_INTVL]);
v->br_mcast_ctx.multicast_query_interval = clock_t_to_jiffies(val);
br_multicast_set_query_intvl(&v->br_mcast_ctx, val);
*changed = true;
}
if (tb[BRIDGE_VLANDB_GOPTS_MCAST_QUERY_RESPONSE_INTVL]) {