On Wed, Dec 28, 2022 at 10:16:45PM -0500, Neal Gompa wrote: > On Wed, Dec 28, 2022 at 10:13 PM Peter Hutterer > <peter.hutterer@xxxxxxxxx> wrote: > > > > On Thu, Dec 22, 2022 at 05:41:06AM -0500, Neal Gompa wrote: > > > On Thu, Dec 22, 2022 at 5:30 AM Niklas Schnelle <schnelle@xxxxxxxxxxxxx> wrote: > > > > > > > > Hi All, > > > > > > > > This might not be as niche as you might think. I'm one of the > > > > Linux kernel maintainers for s390. Many of us do the vast majority of > > > > their development work natively on s390 systems via SSH from Fedora > > > > laptops. After all mainframes are pretty damn fast at compiling with > > > > plenty of memory and dog fooding is part of quality control. And I'm > > > > sure it's not just the teams working on the Linux kernel but also > > > > plenty of other people working with s390 Linux machines. These s390 > > > > machines mostly only host X servers via VNC and usually just for the > > > > installation but they do that too. There is also a hand full of X > > > > clients I run on s390 which are essential for my and many of my > > > > colleagues daily workflows. The most important one is defintely > > > > xsel/xclip to copy from the (neo-)vim/tmux I use for coding to my local > > > > system. Some people also use x3270 via SSH X forwarding from jumphosts, > > > > others use XEmacs. I also know essential internal tools that are run on > > > > s390 hosts via X forwarding. Sure people using X forwarding are capable > > > > of changing configuration defaults but if at all possible I would > > > > suggest to rethink this, as it will create significant hassle for > > > > anyone using their Fedora systems to SSH + X forward to s390 Linux > > > > hosts and it definitely sees more use and thus testing than the > > > > proposal makes it sound. > > > > > > > > > > How bad would it be to force little-endian for the X protocol > > > regardless of architecture? > > > > simply said - not realistic. It's a lot of effort, with zero visible > > benefit beyond the *potential* that we're slightly safer now. Which you > > won't know until you tested it all. > > > > The code works, at least for the bits that are executed. Swapped clients > > run on different hosts by definition so there are probably whole > > extensions that are never used at all and likely completely untested. > > And it's not a matter of "working" but "safe against a malicious client > > sending bad messages". That's a completely different ballpark. > > e.g. the code for CVE-2022-46340 has been there since ~2008 but no-one > > ever noticed the issue - because it works as long as the client is nice. > > > > Forcing the server to little endian only means you'd need to do the > > swapping client-side. There is nothing in place right now to do this and > > while it's probably possible to automate this somewhat with xcb, you're > > still looking at a huge project. And once it all works, you need to > > ensure it works against malicious input data. You could *possibly* MITM > > the whole protocol-swapping into a separate process but, well, goto 10 > > :) > > > > Please tell me the Wayland protocol doesn't do this? 🙏 the wayland protocol doesn't to this :) Wayland integers must be encoded in the host's (read: compositor) byte order. Somewhat of an exception are the wl_shm image formats which are (apparently) always in little-endian [1]. Cheers, Peter [1] https://wayland.freedesktop.org/docs/html/apa.html _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
