Merge branch 'net-bridge-mcast-add-and-enforce-query-interval-minimum'

Nikolay Aleksandrov says:

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

This set adds and enforces 1 second minimum value for bridge multicast
query and startup query intervals in order to avoid rearming the timers
too often which could lock and crash the host. I doubt anyone is using
such low values or anything lower than 1 second, so it seems like a good
minimum. In order to be compatible if the value is lower then it is
overwritten and a log message is emitted, since we can't return an error
at this point.

Eric, I looked for the syzbot reports in its dashboard but couldn't find
them so I've added you as the reporter.

I've prepared a global bridge igmp rate limiting patch but wasn't
sure if it's ok for -net. It adds a static limit of 32k packets per
second, I plan to send it for net-next with added drop counters for
each bridge so it can be easily debugged.

Original report can be seen at:
https://lore.kernel.org/netdev/e8b9ce41-57b9-b6e2-a46a-ff9c791cf0ba@gmail.com/
====================

Link: https://lore.kernel.org/r/20211227172116.320768-1-nikolay@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 44 insertions, 6 deletions

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index f3d751105343c..de24098894897 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -4522,6 +4522,38 @@ 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;
+}
+
+void br_multicast_set_startup_query_intvl(struct net_bridge_mcast *brmctx,
+					  unsigned long val)
+{
+	unsigned long intvl_jiffies = clock_t_to_jiffies(val);
+
+	if (intvl_jiffies < BR_MULTICAST_STARTUP_QUERY_INTVL_MIN) {
+		br_info(brmctx->br,
+			"trying to set multicast startup query interval below minimum, setting to %lu (%ums)\n",
+			jiffies_to_clock_t(BR_MULTICAST_STARTUP_QUERY_INTVL_MIN),
+			jiffies_to_msecs(BR_MULTICAST_STARTUP_QUERY_INTVL_MIN));
+		intvl_jiffies = BR_MULTICAST_STARTUP_QUERY_INTVL_MIN;
+	}
+
+	brmctx->multicast_startup_query_interval = intvl_jiffies;
+}
+
 /**
  * br_multicast_list_adjacent - Returns snooped multicast addresses
  * @dev:	The bridge port adjacent to which to retrieve addresses
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 0c8b5f1a15bc0..2ff83d84230d3 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -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]) {
@@ -1369,7 +1369,7 @@ static int br_changelink(struct net_device *brdev, struct nlattr *tb[],
 	if (data[IFLA_BR_MCAST_STARTUP_QUERY_INTVL]) {
 		u64 val = nla_get_u64(data[IFLA_BR_MCAST_STARTUP_QUERY_INTVL]);
 
-		br->multicast_ctx.multicast_startup_query_interval = clock_t_to_jiffies(val);
+		br_multicast_set_startup_query_intvl(&br->multicast_ctx, val);
 	}
 
 	if (data[IFLA_BR_MCAST_STATS_ENABLED]) {
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index c0efd697865ab..2187a0c3fd222 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -28,6 +28,8 @@
 #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_MULTICAST_STARTUP_QUERY_INTVL_MIN BR_MULTICAST_QUERY_INTVL_MIN
 
 #define BR_HWDOM_MAX BITS_PER_LONG
 
@@ -963,6 +965,10 @@ 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);
+void br_multicast_set_startup_query_intvl(struct net_bridge_mcast *brmctx,
+					  unsigned long val);
 
 static inline bool br_group_is_l2(const struct br_ip *group)
 {
diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index d9a89ddd03310..7b0c19772111c 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -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;
 }
 
@@ -706,7 +706,7 @@ static ssize_t multicast_startup_query_interval_show(
 static int set_startup_query_interval(struct net_bridge *br, unsigned long val,
 				      struct netlink_ext_ack *extack)
 {
-	br->multicast_ctx.multicast_startup_query_interval = clock_t_to_jiffies(val);
+	br_multicast_set_startup_query_intvl(&br->multicast_ctx, val);
 	return 0;
 }
 
diff --git a/net/bridge/br_vlan_options.c b/net/bridge/br_vlan_options.c
index 8ffd4ed2563c6..a6382973b3e70 100644
--- a/net/bridge/br_vlan_options.c
+++ b/net/bridge/br_vlan_options.c
@@ -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]) {
@@ -535,7 +535,7 @@ static int br_vlan_process_global_one_opts(const struct net_bridge *br,
 		u64 val;
 
 		val = nla_get_u64(tb[BRIDGE_VLANDB_GOPTS_MCAST_STARTUP_QUERY_INTVL]);
-		v->br_mcast_ctx.multicast_startup_query_interval = clock_t_to_jiffies(val);
+		br_multicast_set_startup_query_intvl(&v->br_mcast_ctx, val);
 		*changed = true;
 	}
 	if (tb[BRIDGE_VLANDB_GOPTS_MCAST_QUERIER]) {