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netlink: factor out extack composition 

The ext_ack writing code looks very "organically grown".
Move the calculation of the size and writing out to helpers.
This is more idiomatic and gives us the ability to return early
avoiding the long (and randomly ordered) "if" conditions.

Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Jakub Kicinski 2022-08-25 20:09:30 -07:00 committed by Paolo Abeni
parent 47cf88993c
commit 0c95cea24f
1 changed files with 55 additions and 30 deletions
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85
net/netlink/af_netlink.c
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@ -2400,6 +2400,57 @@ error_free:
}
EXPORT_SYMBOL(__netlink_dump_start);
static size_t
netlink_ack_tlv_len(struct netlink_sock *nlk, int err,
const struct netlink_ext_ack *extack)
{
size_t tlvlen;
if (!extack || !(nlk->flags & NETLINK_F_EXT_ACK))
return 0;
tlvlen = 0;
if (extack->_msg)
tlvlen += nla_total_size(strlen(extack->_msg) + 1);
if (extack->cookie_len)
tlvlen += nla_total_size(extack->cookie_len);
/* Following attributes are only reported as error (not warning) */
if (!err)
return tlvlen;
if (extack->bad_attr)
tlvlen += nla_total_size(sizeof(u32));
if (extack->policy)
tlvlen += netlink_policy_dump_attr_size_estimate(extack->policy);
return tlvlen;
}
static void
netlink_ack_tlv_fill(struct sk_buff *in_skb, struct sk_buff *skb,
struct nlmsghdr *nlh, int err,
const struct netlink_ext_ack *extack)
{
if (extack->_msg)
WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg));
if (extack->cookie_len)
WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
extack->cookie_len, extack->cookie));
if (!err)
return;
if (extack->bad_attr &&
!WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
(u8 *)extack->bad_attr >= in_skb->data + in_skb->len))
WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
(u8 *)extack->bad_attr - (u8 *)nlh));
if (extack->policy)
netlink_policy_dump_write_attr(skb, extack->policy,
NLMSGERR_ATTR_POLICY);
}
void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
const struct netlink_ext_ack *extack)
{
@ -2407,29 +2458,20 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
struct nlmsghdr *rep;
struct nlmsgerr *errmsg;
size_t payload = sizeof(*errmsg);
size_t tlvlen = 0;
struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
unsigned int flags = 0;
bool nlk_has_extack = nlk->flags & NETLINK_F_EXT_ACK;
size_t tlvlen;
/* Error messages get the original request appened, unless the user
* requests to cap the error message, and get extra error data if
* requested.
*/
if (nlk_has_extack && extack && extack->_msg)
tlvlen += nla_total_size(strlen(extack->_msg) + 1);
if (err && !(nlk->flags & NETLINK_F_CAP_ACK))
payload += nlmsg_len(nlh);
else
flags |= NLM_F_CAPPED;
if (err && nlk_has_extack && extack && extack->bad_attr)
tlvlen += nla_total_size(sizeof(u32));
if (nlk_has_extack && extack && extack->cookie_len)
tlvlen += nla_total_size(extack->cookie_len);
if (err && nlk_has_extack && extack && extack->policy)
tlvlen += netlink_policy_dump_attr_size_estimate(extack->policy);
tlvlen = netlink_ack_tlv_len(nlk, err, extack);
if (tlvlen)
flags |= NLM_F_ACK_TLVS;
@ -2446,25 +2488,8 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
errmsg->error = err;
memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
if (nlk_has_extack && extack) {
if (extack->_msg) {
WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
extack->_msg));
}
if (err && extack->bad_attr &&
!WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
(u8 *)extack->bad_attr >= in_skb->data +
in_skb->len))
WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
(u8 *)extack->bad_attr -
(u8 *)nlh));
if (extack->cookie_len)
WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
extack->cookie_len, extack->cookie));
if (extack->policy)
netlink_policy_dump_write_attr(skb, extack->policy,
NLMSGERR_ATTR_POLICY);
}
if (tlvlen)
netlink_ack_tlv_fill(in_skb, skb, nlh, err, extack);
nlmsg_end(skb, rep);