On 3/22/21 5:09 PM, Tim Wiederhake wrote: > virsh has several arguments that are better not used. This series introduces > a formal way of marking them as deprecated. Commit messages are rather sparse. What we currently have is hiding options we deem obsolete from users and replacing them with better ones (just :Ggrep VSH_OT_ALIAS). No error message, no warning. What makes these you picked special? I'm not against reporting that an option is obsolete, but I don't quite understand why we need a different way for obsoleting those three.

On 3/23/21 2:42 PM, Daniel P. Berrangé wrote: > On Tue, Mar 23, 2021 at 02:36:19PM +0100, Michal Privoznik wrote: > > On 3/22/21 5:09 PM, Tim Wiederhake wrote: > > > virsh has several arguments that are better not used. This series introduces > > > a formal way of marking them as deprecated. > > > > Commit messages are rather sparse. What we currently have is hiding options > > we deem obsolete from users and replacing them with better ones (just :Ggrep > > VSH_OT_ALIAS). No error message, no warning. What makes these you picked > > special? I'm not against reporting that an option is obsolete, but I don't > > quite understand why we need a different way for obsoleting those three. > > Also the general idea of deprecation is that the thing will be deleted > eventually, which is not something we intended to do with these options. > Basically there's a better way to do these things, but we're not going > to break existing usage, so if users are happy with what they're doing > they don't need to change. > To be fair we never promised virsh to be stable, did we? We are trying to keep it as backwards compatible as we can (and so far I guess we didn't have a single instance of bad example), but I wouldn't mind telling users (esp. in interactive mode) that --optionX is now called --optionY.

On Tue, Mar 23, 2021 at 14:50:09 +0100, Michal Privoznik wrote: > On 3/23/21 2:42 PM, Daniel P. Berrangé wrote: >> On Tue, Mar 23, 2021 at 02:36:19PM +0100, Michal Privoznik wrote: >>> On 3/22/21 5:09 PM, Tim Wiederhake wrote: >>>> virsh has several arguments that are better not used. This series introduces >>>> a formal way of marking them as deprecated. >>> >>> Commit messages are rather sparse. What we currently have is hiding options >>> we deem obsolete from users and replacing them with better ones (just :Ggrep >>> VSH_OT_ALIAS). No error message, no warning. What makes these you picked >>> special? I'm not against reporting that an option is obsolete, but I don't >>> quite understand why we need a different way for obsoleting those three. >> >> Also the general idea of deprecation is that the thing will be deleted >> eventually, which is not something we intended to do with these options. >> Basically there's a better way to do these things, but we're not going >> to break existing usage, so if users are happy with what they're doing >> they don't need to change. >> > > To be fair we never promised virsh to be stable, did we? We are trying to I'd say we do, at least for the reasonably machine-usable interfaces (for output [1]), thus any input options should be treated as such. > keep it as backwards compatible as we can (and so far I guess we didn't have > a single instance of bad example), but I wouldn't mind telling users (esp. > in interactive mode) that --optionX is now called --optionY. Well, that's what we do with the alias and documentation changes. But removing --optionX completely would be wrong:

- It needlessly breaks scripts - If you decide to print a deprecation warning, the code usually won't be much simpler. - most cases are covered by use of _ALIAS to a better name The only thing that IMO should be removed but I didn't for compatibility is the 'secret-set-value's 'base64' parameter as that is insecure. There isn't a compatible replacement though.

On Tue, Mar 23, 2021 at 15:19:44 +0100, Michal Privoznik wrote: > On 3/23/21 3:04 PM, Peter Krempa wrote: > > On Tue, Mar 23, 2021 at 14:50:09 +0100, Michal Privoznik wrote: > > > On 3/23/21 2:42 PM, Daniel P. Berrangé wrote: > > > > On Tue, Mar 23, 2021 at 02:36:19PM +0100, Michal Privoznik > > > > wrote: [...] > > The only thing that IMO should be removed but I didn't for > > compatibility > > is the 'secret-set-value's 'base64' parameter as that is > > insecure. There > > isn't a compatible replacement though. > > > > That's debatable. Its not much worse than reading from a file. I > mean, who > has access to my $HISTFILE? Only me and root and in both cases the > secret It's not about HISTFILE, but about the process listing. On a default linux box, all users can list all other user's processes. If your password is an argument for a command, it will be readable for other users without the access to your directory. Arguably, the lifetime of virsh is very short, so it's extremely unlikely for anyone to notice, but it's insecure regardless. > can be changed or read from the file (if the file is not deleted > right away, > and even then it could be recovered). Many tools accept passwords > in clear > text on cmd line (e.g. curl, wget). If anything, we could document > why You should avoid use of those arguments if you are on a multi-user box. > --base64 is dangerous (if we haven't done so yet). It is documented as such and also prints a warning as pointed out in the other reply.

On Tue, Mar 23, 2021 at 05:23:38PM +0100, Tim Wiederhake wrote: > On Tue, 2021-03-23 at 15:28 +0100, Peter Krempa wrote: > > On Tue, Mar 23, 2021 at 15:19:44 +0100, Michal Privoznik wrote: > > > On 3/23/21 3:04 PM, Peter Krempa wrote: > > > > On Tue, Mar 23, 2021 at 14:50:09 +0100, Michal Privoznik > > > > wrote: > > > > > On 3/23/21 2:42 PM, Daniel P. Berrangé wrote: > > > > > > On Tue, Mar 23, 2021 at 02:36:19PM +0100, Michal > > > > > > Privoznik > > > > > > wrote: > > > > [...] > > > > > > The only thing that IMO should be removed but I didn't for > > > > compatibility > > > > is the 'secret-set-value's 'base64' parameter as that is > > > > insecure. There > > > > isn't a compatible replacement though. > > > > > > > > > > That's debatable. Its not much worse than reading from a file. > > > I > > > mean, who > > > has access to my $HISTFILE? Only me and root and in both cases > > > the > > > secret > > > > It's not about HISTFILE, but about the process listing. On a > > default > > linux box, all users can list all other user's processes. If your > > password is an argument for a command, it will be readable for > > other > > users without the access to your directory. > > > > Arguably, the lifetime of virsh is very short, so it's extremely > > unlikely for anyone to notice, but it's insecure regardless. > > > > > can be changed or read from the file (if the file is not > > > deleted > > > right away, > > > and even then it could be recovered). Many tools accept > > > passwords > > > in clear > > > text on cmd line (e.g. curl, wget). If anything, we could > > > document > > > why > > > > You should avoid use of those arguments if you are on a multi- > > user > > box. > > > > > --base64 is dangerous (if we haven't done so yet). > > > > It is documented as such and also prints a warning as pointed out > > in > > the > > other reply. > > > > Hi all, > > thank you for your feedback! > > My motivation for starting this patch series was the desire to > change > the behavior of the virsh commands "create", "define", "snapshot- > create", "cpu-compare", and "hypervisor-cpu-compare": Currently, > those > commands accept an "--validate" argument that enables RNG schema > validation for the provided XML. In my opinion, this should be the > default behavior. This series was supposed to lay the ground work, > a > formal deprecation system for commands and arguments. > > I understand that suddenly rejecting invalid XML where it was > accepted > previously and seemingly did the right thing breaks backwards > compatibility, even if the only affected users are those with > invalid > XML which should be fixed anyway. To that end, I wrote a small set > of > patches that introduce a "--no-validate" argument to these > commands, > mark that flag as deprecated, and only then make the switch for > enabling validation by default. > > For users with valid XML, this change is invisible. Users with > invalid > XML are being made aware that their XML is broken, but given the > opportunity to continue operations by specifying "--no-validate" > until > their XML is fixed. Their XML is not neccessarily broken. They may simply have included some XML elements from newer libvirt that are not relevant on the current libvirt and be fine with them being ignored. Yes it would be better if they actually tailored the XML for the specific libvirt, but the kind of people using virsh often don't care about this level of perfection.

Note, that we automatically use validation with the 'virsh *edit' commands because those are for interactive users and they often make mistakes resulting in their changes silently disappearing. So in that case validating by default was a clear win with no real downside (assuming bug free schemas). > I will abandon this series and retry with a version that simply > outputs > a warning if the user provides XML data without also using " > --validate", similar to the one for "--base64". This will result in warnings for almost everyone who uses virsh, so I would not be in favour of that.