Virtualization - Jul 2023 - [PATCH 2/2] vdpa: Enable strict validation for netlinks ops

The original patch from Lin Ma enables the vdpa driver to use validation
netlink ops.

The second patch simply disables the validation skip which is no longer
neccesary. Patchset started of from this discussion [0].

[0] https://lore.kernel.org/virtualization/20230726074710-mutt-send-email-mst at
kernel.org/T/#t

v2: cc'ed stable

Dragos Tatulea (1):
  vdpa: Enable strict validation for netlinks ops

Lin Ma (1):
  vdpa: Complement vdpa_nl_policy for nlattr length check

 drivers/vdpa/vdpa.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

-- 
2.41.0

Author: Lin Ma <linma at zju.edu.cn>
The vdpa_nl_policy structure is used to validate the nlattr when parsing
the incoming nlmsg. It will ensure the attribute being described produces
a valid nlattr pointer in info->attrs before entering into each handler
in vdpa_nl_ops.

That is to say, the missing part in vdpa_nl_policy may lead to illegal
nlattr after parsing, which could lead to OOB read just like CVE-2023-3773.

This patch adds three missing nla_policy to avoid such bugs.

Fixes: 90fea5a800c3 ("vdpa: device feature provisioning")
Fixes: 13b00b135665 ("vdpa: Add support for querying vendor
statistics")
Fixes: ad69dd0bf26b ("vdpa: Introduce query of device config layout")
Signed-off-by: Lin Ma <linma at zju.edu.cn>
---
 drivers/vdpa/vdpa.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 965e32529eb8..f2f654fd84e5 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -1247,8 +1247,11 @@ static const struct nla_policy
vdpa_nl_policy[VDPA_ATTR_MAX + 1] = {
 	[VDPA_ATTR_MGMTDEV_DEV_NAME] = { .type = NLA_STRING },
 	[VDPA_ATTR_DEV_NAME] = { .type = NLA_STRING },
 	[VDPA_ATTR_DEV_NET_CFG_MACADDR] = NLA_POLICY_ETH_ADDR,
+	[VDPA_ATTR_DEV_NET_CFG_MAX_VQP] = { .type = NLA_U16 },
 	/* virtio spec 1.1 section 5.1.4.1 for valid MTU range */
 	[VDPA_ATTR_DEV_NET_CFG_MTU] = NLA_POLICY_MIN(NLA_U16, 68),
+	[VDPA_ATTR_DEV_QUEUE_INDEX] = { .type = NLA_U32 },
+	[VDPA_ATTR_DEV_FEATURES] = { .type = NLA_U64 },
 };
 
 static const struct genl_ops vdpa_nl_ops[] = {
-- 
2.41.0

The previous patch added the missing nla policies that were required for
validation to work.

Now strict validation on netlink ops can be enabled. This patch does it.

Signed-off-by: Dragos Tatulea <dtatulea at nvidia.com>
---
 drivers/vdpa/vdpa.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index f2f654fd84e5..a7612e0783b3 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -1257,37 +1257,31 @@ static const struct nla_policy
vdpa_nl_policy[VDPA_ATTR_MAX + 1] = {
 static const struct genl_ops vdpa_nl_ops[] = {
 	{
 		.cmd = VDPA_CMD_MGMTDEV_GET,
-		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 		.doit = vdpa_nl_cmd_mgmtdev_get_doit,
 		.dumpit = vdpa_nl_cmd_mgmtdev_get_dumpit,
 	},
 	{
 		.cmd = VDPA_CMD_DEV_NEW,
-		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 		.doit = vdpa_nl_cmd_dev_add_set_doit,
 		.flags = GENL_ADMIN_PERM,
 	},
 	{
 		.cmd = VDPA_CMD_DEV_DEL,
-		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 		.doit = vdpa_nl_cmd_dev_del_set_doit,
 		.flags = GENL_ADMIN_PERM,
 	},
 	{
 		.cmd = VDPA_CMD_DEV_GET,
-		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 		.doit = vdpa_nl_cmd_dev_get_doit,
 		.dumpit = vdpa_nl_cmd_dev_get_dumpit,
 	},
 	{
 		.cmd = VDPA_CMD_DEV_CONFIG_GET,
-		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 		.doit = vdpa_nl_cmd_dev_config_get_doit,
 		.dumpit = vdpa_nl_cmd_dev_config_get_dumpit,
 	},
 	{
 		.cmd = VDPA_CMD_DEV_VSTATS_GET,
-		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 		.doit = vdpa_nl_cmd_dev_stats_get_doit,
 		.flags = GENL_ADMIN_PERM,
 	},
-- 
2.41.0