Re: [PATCH net-next v3 4/5] net/ipv6: set expires in modify_prefix_route() if RTF_EXPIRES is set.

[Hangbin Liu <liuhangbin@gmail.com>]

On Fri, Feb 02, 2024 at 12:21:59AM -0800, thinker.li@gmail.com wrote:
> From: Kui-Feng Lee <thinker.li@gmail.com>
> 
> Make the decision to set or clean the expires of a route based on the
> RTF_EXPIRES flag, rather than the value of the "expires" argument.
> 
> The function inet6_addr_modify() is the only caller of
> modify_prefix_route(), and it passes the RTF_EXPIRES flag and an expiration
> value. The RTF_EXPIRES flag is turned on or off based on the value of
> valid_lft. The RTF_EXPIRES flag is turned on if valid_lft is a finite value
> (not infinite, not 0xffffffff). Even if valid_lft is 0, the RTF_EXPIRES
> flag remains on. The expiration value being passed is equal to the
> valid_lft value if the flag is on. However, if the valid_lft value is
> infinite, the expiration value becomes 0 and the RTF_EXPIRES flag is turned
> off. Despite this, modify_prefix_route() decides to set the expiration
> value if the received expiration value is not zero. This mixing of infinite
> and zero cases creates an inconsistency.
> 
> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
> ---
>  net/ipv6/addrconf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 36bfa987c314..2f6cf6314646 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -4788,7 +4788,7 @@ static int modify_prefix_route(struct inet6_ifaddr *ifp,
>  	} else {
>  		table = f6i->fib6_table;
>  		spin_lock_bh(&table->tb6_lock);
> -		if (!expires) {
> +		if (!(flags & RTF_EXPIRES)) {

Hi Kui-Feng,

I may missed something. But I still could not get why we shouldn't use
expires for checking? If expires == 0, but RTF_EXPIRES is on,
shouldn't we call fib6_clean_expires()?

Thanks
Hangbin
>  			fib6_clean_expires(f6i);
>  			fib6_remove_gc_list(f6i);
>  		} else {
> -- 
> 2.34.1
>