> On 28 Jun 2023, at 22:59, Alexander Chernikov <melif...@freebsd.org> wrote: > > > > On Wed, 28 Jun 2023, at 6:30 AM, Shivank Garg wrote: >> Hi Alexander, >> >> Thanks for replying. >> I think it would mean struct prison info is lost, when it reaches ioctl >> code, Is there some way we can get jail id? > Yes, you should add the hook to the netlink handler. >> >> Another question I have: prison_check_ip4 still relies on checking struct >> prison for flags and ip addr. >> https://github.com/freebsd/freebsd-src/blob/6927176113ee775983952edb3c201fed6be318d3/sys/netinet/in_jail.c#L319 >> How do we handle these cases? > I’ll take a look on the weekend. It may indeed be a problem with nested jails. I looked at the code and after some experiments decided to go with the simplest approach: https://reviews.freebsd.org/D40793 Netlink now passes proper ucred to the ioctl handler, so your code should be able to work out-of-the-box after this lands.
>> >> It used to work for VNET jails inet calls sometime back when I wrote >> mac_ipacl: https://reviews.freebsd.org/D20967 >> - MAC policy to limit jail privilege to set its IP address. We were planning >> to merge this code in 14.0. Is there something we can >> do regarding it? > Yep, sure! I’ll try to further decouple ioctl handler and the actual address > modification code so the ioctl hook wont’t get called in the netlink handler. >> Thanks, >> Shivank >> >> On Wed, 28 Jun 2023 at 04:05, Alexander Chernikov <melif...@freebsd.org >> <mailto:melif...@freebsd.org>> wrote: >> >> >> >> On Fri, 23 Jun 2023, at 10:27 AM, Alexander Chernikov wrote: >>> >>> >>> On Fri, 23 Jun 2023, at 7:53 AM, Shivank Garg wrote: >>>> Hi, >>>> >>>> I want to check credentials of the thread setting the IP address with >>>> SIOCAIFADDR ioctl. >>>> If the thread is jailed (jailed(td_ucred) == 1), I'm applying some checks >>>> on ip address. >>>> >>>> My expectation was that (cred->cr_prison != &prison0) for an ifconfig call >>>> made by the jail. >>> If you’re using -head, it’s a bit more complicated. ifconfig(8) uses >>> rtnetlink(4) interfaces to communicate with the kernel. Privilege check is >>> done in Netlink: >>> https://github.com/freebsd/freebsd-src/blob/764464af49688e74fd6d803df0404ca4726dd460/sys/netlink/route/iface.c#L1472 >>> . After that, (as of now) netlink calls ioctl code from its own kernel >>> thread, which may be the reason of the behavior you’re observing. >> Apparently the previous message was not delivered everywhere. >>>> However, it is showing me some weird behavior. Here are the logs for a >>>> tweaked kernel: >>>> >>>> @@ -339,7 +343,7 @@ in_control(struct socket *so, u_long cmd, void *data, >>>> struct ifnet *ifp, >>>> return (EADDRNOTAVAIL); >>>> struct ucred *cred = (td != NULL) ? td->td_ucred : NULL; >>>> - >>>> + printf("in_control jailed? %d jid %d prison_owns_vnet? >>>> %d\n",jailed(cred),cred->cr_prison->pr_id,prison_owns_vnet(cred)); >>>> >>>> # jexec 1 ifconfig epair0b inet 169.254.123.101/24 >>>> <http://169.254.123.101/24> up >>>> >>>> Dmesg logs: >>>> [256] in_control jailed? 0 jid 0 prison_owns_vnet? 1 >>>> >>>> Cred value indicates host and jail is 0 but the PR_VNET flag is set. >>>> >>>> Is this behavior expected? or something going wrong - what's the next >>>> debug step? >>>> >>>> I greatly appreciate your help! >>>> >>>> Thanks, >>>> Shivank >>> >>> /Alexander >>> >> >> /Alexander > > /Alexander
