diff mbox series

[v3,net-next,4/9] net: dsa: existing DSA masters cannot join upper interfaces

Message ID 20220819174820.3585002-5-vladimir.oltean@nxp.com (mailing list archive)
State Accepted
Commit 4f03dcc6b9a0734d755601002e33adbd42469b47
Delegated to: Netdev Maintainers
Headers show
Series DSA changes for multiple CPU ports (part 3) | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 85 this patch: 85
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 85 this patch: 85
netdev/checkpatch warning WARNING: line length of 85 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Vladimir Oltean Aug. 19, 2022, 5:48 p.m. UTC 
All the traffic to/from a DSA master is supposed to be distributed among
its DSA switch upper interfaces, so we should not allow other upper
device kinds.

An exception to this is DSA_TAG_PROTO_NONE (switches with no DSA tags),
and in that case it is actually expected to create e.g. VLAN interfaces
on the master. But for those, netdev_uses_dsa(master) returns false, so
the restriction doesn't apply.

The motivation for this change is to allow LAG interfaces of DSA masters
to be DSA masters themselves. We want to restrict the user's degrees of
freedom by 1: the LAG should already have all DSA masters as lowers, and
while lower ports of the LAG can be removed, none can be added after the
fact.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
---
v1->v3: none

 net/dsa/slave.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
diff mbox series

Patch

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 09767f4b3b37..5b2e8f90ee2c 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -2699,6 +2699,35 @@  dsa_slave_prechangeupper_sanity_check(struct net_device *dev,
 	return NOTIFY_DONE;
 }
 
+static int
+dsa_master_prechangeupper_sanity_check(struct net_device *master,
+				       struct netdev_notifier_changeupper_info *info)
+{
+	struct netlink_ext_ack *extack;
+
+	if (!netdev_uses_dsa(master))
+		return NOTIFY_DONE;
+
+	if (!info->linking)
+		return NOTIFY_DONE;
+
+	/* Allow DSA switch uppers */
+	if (dsa_slave_dev_check(info->upper_dev))
+		return NOTIFY_DONE;
+
+	/* Allow bridge uppers of DSA masters, subject to further
+	 * restrictions in dsa_bridge_prechangelower_sanity_check()
+	 */
+	if (netif_is_bridge_master(info->upper_dev))
+		return NOTIFY_DONE;
+
+	extack = netdev_notifier_info_to_extack(&info->info);
+
+	NL_SET_ERR_MSG_MOD(extack,
+			   "DSA master cannot join unknown upper interfaces");
+	return notifier_from_errno(-EBUSY);
+}
+
 /* Don't allow bridging of DSA masters, since the bridge layer rx_handler
  * prevents the DSA fake ethertype handler to be invoked, so we don't get the
  * chance to strip off and parse the DSA switch tag protocol header (the bridge
@@ -2753,6 +2782,10 @@  static int dsa_slave_netdevice_event(struct notifier_block *nb,
 		if (notifier_to_errno(err))
 			return err;
 
+		err = dsa_master_prechangeupper_sanity_check(dev, info);
+		if (notifier_to_errno(err))
+			return err;
+
 		err = dsa_bridge_prechangelower_sanity_check(dev, info);
 		if (notifier_to_errno(err))
 			return err;