linux-kernel - RE: [RFC PATCH net-next] net: Modify CSUM capability check for USO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID:
 <SA1PR12MB81638B84395740F6F08D44719DDE2@SA1PR12MB8163.namprd12.prod.outlook.com>
Date: Tue, 18 Mar 2025 07:01:47 +0000
From: "Radharapu, Rakesh" <Rakesh.Radharapu@....com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>, Paolo Abeni
	<pabeni@...hat.com>, "git (AMD-Xilinx)" <git@....com>, "davem@...emloft.net"
	<davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>, "horms@...nel.org" <horms@...nel.org>,
	"kuniyu@...zon.com" <kuniyu@...zon.com>, "bigeasy@...utronix.de"
	<bigeasy@...utronix.de>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "Katakam,
 Harini" <harini.katakam@....com>, "Pandey, Radhey Shyam"
	<radhey.shyam.pandey@....com>, "Simek, Michal" <michal.simek@....com>
Subject: RE: [RFC PATCH net-next] net: Modify CSUM capability check for USO

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
> Sent: Sunday, March 16, 2025 7:35 AM
> To: Radharapu, Rakesh <Rakesh.Radharapu@....com>; Paolo Abeni
> <pabeni@...hat.com>; git (AMD-Xilinx) <git@....com>;
> davem@...emloft.net; edumazet@...gle.com; kuba@...nel.org;
> horms@...nel.org; kuniyu@...zon.com; bigeasy@...utronix.de
> Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org; Katakam, Harini
> <harini.katakam@....com>; Pandey, Radhey Shyam
> <radhey.shyam.pandey@....com>; Simek, Michal
> <michal.simek@....com>
> Subject: RE: [RFC PATCH net-next] net: Modify CSUM capability check for USO
>
> Caution: This message originated from an External Source. Use proper
> caution when opening attachments, clicking links, or responding.
>
>
> Radharapu, Rakesh wrote:
> > [AMD Official Use Only - AMD Internal Distribution Only]
> >
> > > -----Original Message-----
> > > From: Paolo Abeni <pabeni@...hat.com>
> > > Sent: Wednesday, March 12, 2025 9:44 PM
> > > To: Radharapu, Rakesh <Rakesh.Radharapu@....com>; git (AMD-Xilinx)
> > > <git@....com>; davem@...emloft.net; edumazet@...gle.com;
> > > kuba@...nel.org; horms@...nel.org; kuniyu@...zon.com;
> > > bigeasy@...utronix.de
> > > Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org; Katakam,
> > > Harini <harini.katakam@....com>; Pandey, Radhey Shyam
> > > <radhey.shyam.pandey@....com>; Simek, Michal
> <michal.simek@....com>
> > > Subject: Re: [RFC PATCH net-next] net: Modify CSUM capability check
> > > for USO
> > >
> > > Caution: This message originated from an External Source. Use proper
> > > caution when opening attachments, clicking links, or responding.
> > >
> > >
> > > On 3/12/25 12:54 PM, Radharapu Rakesh wrote:
> > > >  net/core/dev.c | 8 +++++---
> > > >  1 file changed, 5 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/net/core/dev.c b/net/core/dev.c index
> > > > 1cb134ff7327..a22f8f6e2ed1 100644
> > > > --- a/net/core/dev.c
> > > > +++ b/net/core/dev.c
> > > > @@ -10465,11 +10465,13 @@ static void
> > > > netdev_sync_lower_features(struct net_device *upper,
> > > >
> > > >  static bool netdev_has_ip_or_hw_csum(netdev_features_t features)  {
> > > > -     netdev_features_t ip_csum_mask = NETIF_F_IP_CSUM |
> > > NETIF_F_IPV6_CSUM;
> > > > -     bool ip_csum = (features & ip_csum_mask) == ip_csum_mask;
> > > > +     netdev_features_t ipv4_csum_mask = NETIF_F_IP_CSUM;
> > > > +     netdev_features_t ipv6_csum_mask = NETIF_F_IPV6_CSUM;
> > > > +     bool ipv4_csum = (features & ipv4_csum_mask) ==
> ipv4_csum_mask;
> > > > +     bool ipv6_csum = (features & ipv6_csum_mask) ==
> > > > + ipv6_csum_mask;
> > > >       bool hw_csum = features & NETIF_F_HW_CSUM;
> > > >
> > > > -     return ip_csum || hw_csum;
> > > > +     return ipv4_csum || ipv6_csum || hw_csum;
> > > >  }
> > >
> > > The above will additionally affect TLS offload, and will likely
> > > break i.e. USO over IPv6 traffic landing on devices supporting only
> > > USO over IPv4, unless such devices additionally implement a suitable
> ndo_features_check().
> > >
> > > Such situation will be quite bug prone, I'm unsure we want this kind
> > > of change
> > > - even without looking at the TLS side of it.
> > >
> > > /P
> > Thanks for your review. I understand that this will lead to an issue.
> > We have a device that supports only IPv4 CSUM and are unable to enable
> > the USO feature because of this check. Can you please let me know if
> > splitting GSO feature for IPv4 and IPv6 would be helpful? That way
> > corresponding CSUM offloads can be checked. But this would be a major
> change.
> > Will appreciate any other suggestions.
>
> Splitting NETIF_F_GSO_UDP_L4 would incur significant churn.
>
> Since this is a limitation of a specific device, can you instead advertise the
> feature, but for IPv6 packets drop the flag in ndo_features_check?

Yes, Thanks for your reply. I'm making the recommended modification
to the driver and will also monitor performance numbers.
If everything goes well this RFC patch can be dropped.

Regards,
Rakesh