linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Paraschiv, Andra-Irina" <andraprs@amazon.com>
To: Jakub Kicinski <kuba@kernel.org>,
	Stefano Garzarella <sgarzare@redhat.com>
Cc: netdev <netdev@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	David Duncan <davdunc@amazon.com>,
	Dexuan Cui <decui@microsoft.com>, Alexander Graf <graf@amazon.de>,
	Jorgen Hansen <jhansen@vmware.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH net-next v2 1/4] vm_sockets: Include flags field in the vsock address data structure
Date: Thu, 10 Dec 2020 17:29:27 +0200	[thread overview]
Message-ID: <265d2382-3909-cf1d-f3af-4fd14278ad4c@amazon.com> (raw)
In-Reply-To: <20201209093019.1caae20e@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com>



On 09/12/2020 19:30, Jakub Kicinski wrote:
> On Wed, 9 Dec 2020 17:17:56 +0200 Paraschiv, Andra-Irina wrote:
>>> I agree that could be a problem, but here some considerations:
>>> - I checked some applications (qemu-guest-agent, ncat, iperf-vsock) and
>>>    all use the same pattern: allocate memory, initialize all the
>>>    sockaddr_vm to zero (to be sure to initialize the svm_zero), set the
>>>    cid and port fields.
>>>    So we should be safe, but of course it may not always be true.
>>>
>>> - For now the issue could affect only nested VMs. We introduced this
>>>    support one year ago, so it's something new and maybe we don't cause
>>>    too many problems.
>>>
>>> As an alternative, what about using 1 or 2 bytes from svm_zero[]?
>>> These must be set at zero, even if we only check the first byte in the
>>> kernel.
>> Thanks for the follow-up info.
>>
>> We can also consider the "svm_zero" option and could use 2 bytes from
>> that field for "svm_flags", keeping the same "unsigned short" type.
> Or use svm_zero as a gate for interpreting other fields?
> If svm_zero[0]* == something start checking the value of reserved1?
> * in practice the name can be unioned to something more palatable ;)

Thanks for the shared option, that could be one case to reuse the 
reserved field, with a two phase check logic.

I'll give it a try to the option of having a new field "svm_flags" and 
the "svm_zero" updated and then send out a new revision. Just let me 
know if there are other updates needed / questions in the meantime.


struct sockaddr_vm {
     __kernel_sa_family_t svm_family;
     unsigned short svm_reserved1;
     unsigned int svm_port;
     unsigned int svm_cid;
     unsigned short svm_flags;
     unsigned char svm_zero[sizeof(struct sockaddr) -
                    sizeof(sa_family_t) -
                    sizeof(unsigned short) -
                    sizeof(unsigned int) - sizeof(unsigned int) -
sizeof(unsigned short)];
};


Thanks,
Andra



Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.

  reply	other threads:[~2020-12-10 15:31 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-04 17:02 [PATCH net-next v2 0/4] vsock: Add flags field in the vsock address Andra Paraschiv
2020-12-04 17:02 ` [PATCH net-next v2 1/4] vm_sockets: Include flags field in the vsock address data structure Andra Paraschiv
2020-12-07  9:59   ` Stefano Garzarella
2020-12-07 19:25     ` Paraschiv, Andra-Irina
2020-12-07 21:29   ` Jakub Kicinski
2020-12-08 18:23     ` Paraschiv, Andra-Irina
2020-12-08 18:42       ` Jakub Kicinski
2020-12-09 10:48         ` Stefano Garzarella
2020-12-09 15:17           ` Paraschiv, Andra-Irina
2020-12-09 17:30             ` Jakub Kicinski
2020-12-10 15:29               ` Paraschiv, Andra-Irina [this message]
2020-12-04 17:02 ` [PATCH net-next v2 2/4] vm_sockets: Add VMADDR_FLAG_TO_HOST vsock flag Andra Paraschiv
2020-12-07  9:59   ` Stefano Garzarella
2020-12-07 19:45     ` Paraschiv, Andra-Irina
2020-12-04 17:02 ` [PATCH net-next v2 3/4] af_vsock: Set VMADDR_FLAG_TO_HOST flag on the receive path Andra Paraschiv
2020-12-07  9:59   ` Stefano Garzarella
2020-12-04 17:02 ` [PATCH net-next v2 4/4] af_vsock: Assign the vsock transport considering the vsock address flags Andra Paraschiv
2020-12-07 10:00   ` Stefano Garzarella
2020-12-07 19:51     ` Paraschiv, Andra-Irina
2020-12-07 10:05 ` [PATCH net-next v2 0/4] vsock: Add flags field in the vsock address Stefano Garzarella
2020-12-07 19:18   ` Paraschiv, Andra-Irina

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=265d2382-3909-cf1d-f3af-4fd14278ad4c@amazon.com \
    --to=andraprs@amazon.com \
    --cc=davdunc@amazon.com \
    --cc=davem@davemloft.net \
    --cc=decui@microsoft.com \
    --cc=graf@amazon.de \
    --cc=jhansen@vmware.com \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=sgarzare@redhat.com \
    --cc=stefanha@redhat.com \
    --cc=vkuznets@redhat.com \
    --subject='Re: [PATCH net-next v2 1/4] vm_sockets: Include flags field in the vsock address data structure' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).