Messages in this thread | | | From | Rocco Yue <> | Subject | Re: [PATCH net-next v2] ipv6: add IFLA_INET6_RA_MTU to expose mtu value in the RA message | Date | Mon, 2 Aug 2021 20:40:39 +0800 |
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On Sat, 2021-07-31 at 11:17 -0600, David Ahern wrote: On 7/30/21 7:52 PM, Rocco Yue wrote:
> IFLA_INET6_RA_MTU set. You can set "reject_message" in the policy to > return a message that "IFLA_INET6_RA_MTU can not be set".
Hi David,
Regarding setting "reject_message" in the policy, after reviewing the code, I fell that it is unnecessary, because the cost of implementing it seems to be a bit high, which requires modifying the function interface. The reasons is as follows:
The parameter "struct netlink_ext_ack *extack" is not exposed in the function inet6_validate_link_af(), and the last argument when calling nla_parse_nested_deprecated() is NULL, which makes the user space not notified even if reject_message is set.
static int inet6_validate_link_af(...) { ... err = nla_parse_nested_deprecated(tb, IFLA_INET6_MAX, nla, inet6_af_policy, NULL); ... }
Only when extack is not NULL, reject_message is valid.
static int validate_nla(...) { ... switch (pt->type) { case NLA_REJECT: if (extack && pt->reject_message) { NL_SET_BAD_ATTR(extack, nla); extack->_msg = pt->reject_message; return -EINVAL; } err = -EINVAL; goto out_err; ... }
Thanks Rocco
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