[PATCH net-next 1/2] net: dsa: mv88e6xxx: check the port when reading back a policy rule

chip->policies is one IDR for the whole switch, so the location an
ETHTOOL_GRXCLSRULE caller supplies can name a rule belonging to any port.
mv88e6xxx_get_rxnfc() copies it out without looking at policy->port, which
lets a user on one user port read the MAC address and VID of a policy an
admin installed on another.  ETHTOOL_GRXCLSRULE needs no CAP_NET_ADMIN.

The GRXCLSRLCNT and GRXCLSRLALL arms of the same switch statement already
filter on policy->port, which makes the GRXCLSRULE omission look
unintentional. Nonetheless, changing this does carry some regression
risk.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: andrew@lunn.ch
CC: olteanv@gmail.com
CC: f.fainelli@gmail.com
CC: vivien.didelot@gmail.com
---
 drivers/net/dsa/mv88e6xxx/chip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 7f68a0c55802..daef7c78b860 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c

@@ -2457,7 +2457,7 @@ static int mv88e6xxx_get_rxnfc(struct dsa_switch *ds, int port,
 	case ETHTOOL_GRXCLSRULE:
 		err = -ENOENT;
 		policy = idr_find(&chip->policies, fs->location);
-		if (policy) {
+		if (policy && policy->port == port) {
 			memcpy(fs, &policy->fs, sizeof(*fs));
 			err = 0;
 		}

-- 
2.55.0