[PATCH net-next 04/15] net: dsa: sja1105: deny alterations of dsa_8021q VLANs from the bridge

From: Vladimir Oltean
Date: Sun May 10 2020 - 12:44:45 EST


From: Vladimir Oltean <vladimir.oltean@xxxxxxx>

At the moment, this can never happen. The 2 modes that we operate in do
not permit that:

- SJA1105_VLAN_UNAWARE: we are guarded from bridge VLANs added by the
user by the DSA core. We will later lift this restriction by setting
ds->vlan_bridge_vtu = true, and that is where we'll need it.

- SJA1105_VLAN_FILTERING_FULL: in this mode, dsa_8021q configuration is
disabled. So the user is free to add these VLANs in the 1024-3071
range.

The reason for the patch is that we'll introduce a third VLAN awareness
state, where both dsa_8021q as well as the bridge are going to call our
.port_vlan_add and .port_vlan_del methods.

For that, we need a good way to discriminate between the 2. The easiest
(and less intrusive way for upper layers) is to recognize the fact that
dsa_8021q configurations are always driven by our driver - we _know_
when a .port_vlan_add method will be called from dsa_8021q because _we_
initiated it.

So introduce an expect_dsa_8021q boolean which is only used, at the
moment, for blacklisting VLANs in range 1024-3071 in the modes when
dsa_8021q is active.

Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
---
drivers/net/dsa/sja1105/sja1105.h | 1 +
drivers/net/dsa/sja1105/sja1105_main.c | 31 +++++++++++++++++++++++++-
2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/sja1105/sja1105.h b/drivers/net/dsa/sja1105/sja1105.h
index 5b2b275d01a7..667056d0c819 100644
--- a/drivers/net/dsa/sja1105/sja1105.h
+++ b/drivers/net/dsa/sja1105/sja1105.h
@@ -198,6 +198,7 @@ struct sja1105_private {
* the switch doesn't confuse them with one another.
*/
struct mutex mgmt_lock;
+ bool expect_dsa_8021q;
enum sja1105_vlan_state vlan_state;
struct sja1105_tagger_data tagger_data;
struct sja1105_ptp_data ptp_data;
diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index 7dee9b282a1b..78ec97850f96 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -1811,15 +1811,19 @@ static int sja1105_crosschip_bridge_join(struct dsa_switch *ds,
if (dsa_to_port(ds, port)->bridge_dev != br)
continue;

+ other_priv->expect_dsa_8021q = true;
rc = dsa_8021q_crosschip_bridge_join(ds, port, other_ds,
other_port, br,
&priv->crosschip_links);
+ other_priv->expect_dsa_8021q = false;
if (rc)
return rc;

+ priv->expect_dsa_8021q = true;
rc = dsa_8021q_crosschip_bridge_join(other_ds, other_port, ds,
port, br,
&other_priv->crosschip_links);
+ priv->expect_dsa_8021q = false;
if (rc)
return rc;
}
@@ -1846,12 +1850,16 @@ static void sja1105_crosschip_bridge_leave(struct dsa_switch *ds,
if (dsa_to_port(ds, port)->bridge_dev != br)
continue;

+ other_priv->expect_dsa_8021q = true;
dsa_8021q_crosschip_bridge_leave(ds, port, other_ds, other_port,
br, &priv->crosschip_links);
+ other_priv->expect_dsa_8021q = false;

+ priv->expect_dsa_8021q = true;
dsa_8021q_crosschip_bridge_leave(other_ds, other_port, ds,
port, br,
&other_priv->crosschip_links);
+ priv->expect_dsa_8021q = false;
}
}

@@ -1862,8 +1870,10 @@ static int sja1105_replay_crosschip_vlans(struct dsa_switch *ds, bool enabled)
int rc;

list_for_each_entry(c, &priv->crosschip_links, list) {
+ priv->expect_dsa_8021q = true;
rc = dsa_8021q_crosschip_link_apply(ds, c->port, c->other_ds,
c->other_port, enabled);
+ priv->expect_dsa_8021q = false;
if (rc)
break;
}
@@ -1873,10 +1883,13 @@ static int sja1105_replay_crosschip_vlans(struct dsa_switch *ds, bool enabled)

static int sja1105_setup_8021q_tagging(struct dsa_switch *ds, bool enabled)
{
+ struct sja1105_private *priv = ds->priv;
int rc, i;

for (i = 0; i < SJA1105_NUM_PORTS; i++) {
+ priv->expect_dsa_8021q = true;
rc = dsa_port_setup_8021q_tagging(ds, i, enabled);
+ priv->expect_dsa_8021q = false;
if (rc < 0) {
dev_err(ds->dev, "Failed to setup VLAN tagging for port %d: %d\n",
i, rc);
@@ -1901,10 +1914,26 @@ sja1105_get_tag_protocol(struct dsa_switch *ds, int port,
return DSA_TAG_PROTO_SJA1105;
}

-/* This callback needs to be present */
static int sja1105_vlan_prepare(struct dsa_switch *ds, int port,
const struct switchdev_obj_port_vlan *vlan)
{
+ struct sja1105_private *priv = ds->priv;
+ u16 vid;
+
+ if (priv->vlan_state == SJA1105_VLAN_FILTERING_FULL)
+ return 0;
+
+ /* If the user wants best-effort VLAN filtering (aka vlan_filtering
+ * bridge plus tagging), be sure to at least deny alterations to the
+ * configuration done by dsa_8021q.
+ */
+ for (vid = vlan->vid_begin; vid <= vlan->vid_end; vid++) {
+ if (!priv->expect_dsa_8021q && vid_is_dsa_8021q(vid)) {
+ dev_err(ds->dev, "Range 1024-3071 reserved for dsa_8021q operation\n");
+ return -EBUSY;
+ }
+ }
+
return 0;
}

--
2.17.1