2025-03-04, 13:11:28 +0100, Antonio Quartulli wrote:
On 04/03/2025 13:00, Sabrina Dubroca wrote:
2025-03-04, 01:33:50 +0100, Antonio Quartulli wrote:
int ovpn_nl_key_new_doit(struct sk_buff *skb, struct genl_info *info) {
...
- pkr.slot = nla_get_u8(attrs[OVPN_A_KEYCONF_SLOT]);
- pkr.key.key_id = nla_get_u16(attrs[OVPN_A_KEYCONF_KEY_ID]);
- pkr.key.cipher_alg = nla_get_u16(attrs[OVPN_A_KEYCONF_CIPHER_ALG]);
[...]
+static int ovpn_nl_send_key(struct sk_buff *skb, const struct genl_info *info,
u32 peer_id, enum ovpn_key_slot slot,const struct ovpn_key_config *keyconf)+{
...
- if (nla_put_u32(skb, OVPN_A_KEYCONF_SLOT, slot) ||
nla_put_u32(skb, OVPN_A_KEYCONF_KEY_ID, keyconf->key_id) ||nla_put_u32(skb, OVPN_A_KEYCONF_CIPHER_ALG, keyconf->cipher_alg))That's a bit inconsistent. nla_put_u32 matches the generated policy, but the nla_get_u{8,16} don't (and nla_get_u16 also doesn't match "u8 key_id" it's getting stored into).
[also kind of curious that the policy/spec uses U32 with max values of 1/2/7]
From https://www.kernel.org/doc/html/next/userspace-api/netlink/specs.html#fix-wi...
"Note that types smaller than 32 bit should be avoided as using them does not save any memory in Netlink messages (due to alignment)."
Hence I went for u32 attributes, although values stored into them are much smaller.
Right.
int ovpn_nl_key_get_doit(struct sk_buff *skb, struct genl_info *info) {
...
- slot = nla_get_u32(attrs[OVPN_A_KEYCONF_SLOT]);
int ovpn_nl_key_del_doit(struct sk_buff *skb, struct genl_info *info) {
...
- slot = nla_get_u8(attrs[OVPN_A_KEYCONF_SLOT]);
Right. Since actual values are smaller I sometimes used the smaller macro.
Which only works on little-endian if the other side is using the full size?
LE BE put_u32(1) -> 01000000 00000001 get_u8 ^^ ^^ =1 =0
(and put_u8(1) vs get_u32 would result in fetching 0x1000000 in BE)
I guess I better convert them all to u32.
SGTM
A few more inconsistencies:
- OVPN_A_IFNAME is defined in the uapi but never used (I guess leftover from genl link creation)
Ouch, I guess you're right about it being a leftover.
- OVPN_A_PEER_DEL_REASON (u32 vs u8)
drivers/net/ovpn/netlink-gen.c:52: [OVPN_A_PEER_DEL_REASON] = NLA_POLICY_MAX(NLA_U32, 4), drivers/net/ovpn/netlink.c:1131: if (nla_put_u8(msg, OVPN_A_PEER_DEL_REASON, peer->delete_reason))
Like above, probably better to convert them all to u32.
[...]
u32 should be enough for packets - but yeah, going UINT is better as I don't need to care if it really fits 4B or not.
And that SGTM too. Thanks.