genetlink: start to validate reserved header bytes

We had historically not checked that genlmsghdr.reserved
is 0 on input which prevents us from using those precious
bytes in the future.

One use case would be to extend the cmd field, which is
currently just 8 bits wide and 256 is not a lot of commands
for some core families.

To make sure that new families do the right thing by default
put the onus of opting out of validation on existing families.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com> (NetLabel)
Signed-off-by: David S. Miller <davem@davemloft.net>

10 files changed, 10 insertions, 0 deletions

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 2a709daefbc4..6cec9ce23fd3 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -2322,6 +2322,7 @@ static struct genl_family nbd_genl_family __ro_after_init = {
 	.module		= THIS_MODULE,
 	.small_ops	= nbd_connect_genl_ops,
 	.n_small_ops	= ARRAY_SIZE(nbd_connect_genl_ops),
+	.resv_start_op	= NBD_CMD_STATUS + 1,
 	.maxattr	= NBD_ATTR_MAX,
 	.policy = nbd_attr_policy,
 	.mcgrps		= nbd_mcast_grps,
diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index a208e2b1a9af..15c7dc82107f 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -1859,6 +1859,7 @@ static struct genl_family gtp_genl_family __ro_after_init = {
 	.module		= THIS_MODULE,
 	.small_ops	= gtp_genl_ops,
 	.n_small_ops	= ARRAY_SIZE(gtp_genl_ops),
+	.resv_start_op	= GTP_CMD_ECHOREQ + 1,
 	.mcgrps		= gtp_genl_mcgrps,
 	.n_mcgrps	= ARRAY_SIZE(gtp_genl_mcgrps),
 };
diff --git a/drivers/net/ieee802154/mac802154_hwsim.c b/drivers/net/ieee802154/mac802154_hwsim.c
index 38c217bd7c82..2f0544dd7c2a 100644
--- a/drivers/net/ieee802154/mac802154_hwsim.c
+++ b/drivers/net/ieee802154/mac802154_hwsim.c
@@ -630,6 +630,7 @@ static struct genl_family hwsim_genl_family __ro_after_init = {
 	.module = THIS_MODULE,
 	.small_ops = hwsim_nl_ops,
 	.n_small_ops = ARRAY_SIZE(hwsim_nl_ops),
+	.resv_start_op = MAC802154_HWSIM_CMD_NEW_EDGE + 1,
 	.mcgrps = hwsim_mcgrps,
 	.n_mcgrps = ARRAY_SIZE(hwsim_mcgrps),
 };
diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index c6d271e5687e..adf448a8162b 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -3404,6 +3404,7 @@ static struct genl_family macsec_fam __ro_after_init = {
 	.module		= THIS_MODULE,
 	.small_ops	= macsec_genl_ops,
 	.n_small_ops	= ARRAY_SIZE(macsec_genl_ops),
+	.resv_start_op	= MACSEC_CMD_UPD_OFFLOAD + 1,
 };
 
 static netdev_tx_t macsec_start_xmit(struct sk_buff *skb,
diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index aac133a1e27a..b1e1239dfade 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -2840,6 +2840,7 @@ static struct genl_family team_nl_family __ro_after_init = {
 	.module		= THIS_MODULE,
 	.small_ops	= team_nl_ops,
 	.n_small_ops	= ARRAY_SIZE(team_nl_ops),
+	.resv_start_op	= TEAM_CMD_PORT_LIST_GET + 1,
 	.mcgrps		= team_nl_mcgrps,
 	.n_mcgrps	= ARRAY_SIZE(team_nl_mcgrps),
 };
diff --git a/drivers/net/wireguard/netlink.c b/drivers/net/wireguard/netlink.c
index d0f3b6d7f408..0c0644e762e5 100644
--- a/drivers/net/wireguard/netlink.c
+++ b/drivers/net/wireguard/netlink.c
@@ -621,6 +621,7 @@ static const struct genl_ops genl_ops[] = {
 static struct genl_family genl_family __ro_after_init = {
 	.ops = genl_ops,
 	.n_ops = ARRAY_SIZE(genl_ops),
+	.resv_start_op = WG_CMD_SET_DEVICE + 1,
 	.name = WG_GENL_NAME,
 	.version = WG_GENL_VERSION,
 	.maxattr = WGDEVICE_A_MAX,
diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 4fb8f68e5c3b..d9054104725e 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -5288,6 +5288,7 @@ static struct genl_family hwsim_genl_family __ro_after_init = {
 	.module = THIS_MODULE,
 	.small_ops = hwsim_ops,
 	.n_small_ops = ARRAY_SIZE(hwsim_ops),
+	.resv_start_op = HWSIM_CMD_DEL_MAC_ADDR + 1,
 	.mcgrps = hwsim_mcgrps,
 	.n_mcgrps = ARRAY_SIZE(hwsim_mcgrps),
 };
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 3deaeecb712e..2940559c3086 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -486,6 +486,7 @@ static struct genl_family tcmu_genl_family __ro_after_init = {
 	.netnsok = true,
 	.small_ops = tcmu_genl_ops,
 	.n_small_ops = ARRAY_SIZE(tcmu_genl_ops),
+	.resv_start_op = TCMU_CMD_SET_FEATURES + 1,
 };
 
 #define tcmu_cmd_set_dbi_cur(cmd, index) ((cmd)->dbi_cur = (index))
diff --git a/drivers/thermal/thermal_netlink.c b/drivers/thermal/thermal_netlink.c
index 050d243a5fa1..e2d78a996b5f 100644
--- a/drivers/thermal/thermal_netlink.c
+++ b/drivers/thermal/thermal_netlink.c
@@ -693,6 +693,7 @@ static struct genl_family thermal_gnl_family __ro_after_init = {
 	.policy		= thermal_genl_policy,
 	.small_ops	= thermal_genl_ops,
 	.n_small_ops	= ARRAY_SIZE(thermal_genl_ops),
+	.resv_start_op	= THERMAL_GENL_CMD_CDEV_GET + 1,
 	.mcgrps		= thermal_genl_mcgrps,
 	.n_mcgrps	= ARRAY_SIZE(thermal_genl_mcgrps),
 };
diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index c06c02704461..7badf5777597 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -1183,6 +1183,7 @@ static struct genl_family vdpa_nl_family __ro_after_init = {
 	.module = THIS_MODULE,
 	.ops = vdpa_nl_ops,
 	.n_ops = ARRAY_SIZE(vdpa_nl_ops),
+	.resv_start_op = VDPA_CMD_DEV_VSTATS_GET + 1,
 };
 
 static int vdpa_init(void)