Re: [libvirt PATCHv2 5/9] qemu: virtiofs: do not force UID 0

On a Thursday in 2023, Michal Prívozník wrote: > On 12/13/23 15:47, Ján Tomko wrote: >> When this check was introduced, virtiofsd required root privileges. >> >> This has changed since then - now it does not need to set up all the >> sandboxing when running as non-root. It even gained support for >> id mapping, which makes running unprivileged even more useful. >> >> Signed-off-by: Ján Tomko <jtomko(a)redhat.com&gt; >> --- >>  src/qemu/qemu_virtiofs.c | 4 ---- >>  1 file changed, 4 deletions(-) >> >> diff --git a/src/qemu/qemu_virtiofs.c b/src/qemu/qemu_virtiofs.c >> index af51d58673..4dacd37a1c 100644 >> --- a/src/qemu/qemu_virtiofs.c >> +++ b/src/qemu/qemu_virtiofs.c >> @@ -257,10 +257,6 @@ qemuVirtioFSStart(virQEMUDriver *driver, >>      if (!(cmd = qemuVirtioFSBuildCommandLine(cfg, fs, &fd))) >>          goto error; >> >> -    /* so far only running as root is supported */ >> -    virCommandSetUID(cmd, 0); >> -    virCommandSetGID(cmd, 0); > > This makes us unable to run C version of virtiofsd, becuase that one > does privileged syscalls from the very start. I mean, you can't even run > `virtiofsd --help` as a non-root. The users of the C version (and all the Rust versions that make privileged calls) will still be able to run virtiofsd and it will still be run as root for privileged libvirtd. The downside is a worse error message. If I remember correctly, the only reason I added these lines was a quick way to give unprivileged users an early error without having to write an error message. The above lines were added by: commit f0f986efa8a8e352fbdce7079ec440a4f3c8f522     qemu: add code for handling virtiofsd The proper validation error (which I also propose to remove earlier in this series) was added by: commit efaf46811c909ee5333360fba1d75ae82352964a     qemu: validate virtiofs filesystems Both commits were committed upstream at the same time, so I'm not sure why I kept it there.