Re: [libvirt] [PATCH] docs, rng: Allow a pool name to be line domain name

On 09/28/2017 10:17 AM, Peter Krempa wrote: > On Thu, Sep 28, 2017 at 10:03:55 -0400, John Ferlan wrote: >> >> >> On 09/28/2017 09:47 AM, Peter Krempa wrote: >>> On Wed, Sep 27, 2017 at 15:07:35 -0400, John Ferlan wrote: >>>> https://bugzilla.redhat.com/show_bug.cgi?id=1475250 >>>> >>>> It's possible to define and start a pool with a '.' in the >>>> name; however, when trying to add a volume to a domain using >>>> the storage pool source with a name with a '.' in the name, >>>> the domain RNG validation fails because RNG uses 'genericName' >>>> which does not allow a '.' in the name. Pool definition has >>>> no similar call to virXMLValidateAgainstSchema. Pool name >>>> validation occurs in storagePoolDefineXML and only calls >>>> virXMLCheckIllegalChars using the same parameter "\n" as >>>> qemuDomainDefineXMLFlags would check after the RNG check >>>> could be succesful. >>>> >>>> So in order to resolve this, create a poolName definition >>>> in the RNG and allow the pool name and the volume source >>>> pool name to use that definition. >>>> >>>> Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; >>>> --- >>>> docs/schemas/domaincommon.rng | 2 +- >>>> docs/schemas/storagecommon.rng | 8 ++++++++ >>>> docs/schemas/storagepool.rng | 4 ++-- >>>> 3 files changed, 11 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng >>>> index 76852abb3..2cc8dcecf 100644 >>>> --- a/docs/schemas/domaincommon.rng >>>> +++ b/docs/schemas/domaincommon.rng >>>> @@ -1669,7 +1669,7 @@ >>>> <optional> >>>> <element name="source"> >>>> <attribute name="pool"> >>>> - <ref name="genericName"/> >>>> + <ref name="poolName"/> >>>> </attribute> >>>> <attribute name="volume"> >>>> <ref name="volName"/> >>>> diff --git a/docs/schemas/storagecommon.rng b/docs/schemas/storagecommon.rng >>>> index 717f3c603..49578312e 100644 >>>> --- a/docs/schemas/storagecommon.rng >>>> +++ b/docs/schemas/storagecommon.rng >>>> @@ -6,6 +6,14 @@ >>>> <!-- This schema is not designed for standalone use; another file >>>> must include both this file and basictypes.rng --> >>>> >>>> + <define name="poolName"> >>>> + <data type="string"> >>>> + <!-- Use literal newline instead of \n for bug in libxml2 2.7.6 --> >>>> + <param name="pattern">[^ >>>> +]+</param> >>>> + </data> >>>> + </define> >>>> + >>>> <define name='encryption'> >>>> <element name='encryption'> >>>> <attribute name='format'> >>>> diff --git a/docs/schemas/storagepool.rng b/docs/schemas/storagepool.rng >>>> index f0117bd69..52b2044be 100644 >>>> --- a/docs/schemas/storagepool.rng >>>> +++ b/docs/schemas/storagepool.rng >>>> @@ -209,7 +209,7 @@ >>>> <interleave> >>>> <optional> >>>> <element name='name'> >>>> - <ref name='genericName'/> >>>> + <ref name='poolName'/> >>> >>> This means that a name starting with a dot is invalid according to the >>> schema, but the user ignored the schema and the code is not doing enough >>> validation. >>> >>> I'm not convinced that this is the correct solution. VMs disallow dots >>> since the name is used for generating filenames and using '../' as >>> prefix will allow directory traversal exploits. >>> >>> NACK, I think we should disallow pool names with a dot even in the code. >>> It will be slightly harder since there are no 'validate' callbacks for >>> them and you can't disallow them in the parser. >>> >> >> As a test I defined a domain and a pool using ".test" and it worked. >> >> # virsh list >> Id Name State >> ---------------------------------------------------- >> 1 .f23 running >> >> # virsh dumpxml .f23 >> <domain type='kvm' id='1'> >> <name>.f23</name> >> <uuid>e28761fe-ea53-4682-924a-744a4028f146</uuid> >> <memory unit='KiB'>2097152</memory> >> ... >> >> >> The problem with disallowing in code after the fact is how do you handle >> things now that we have allowed it? I have another long standing bug >> where someone doesn't want a space in the name or even worse a space as >> the name. > > Fair enough, in fact qemu driver (and others which rely on files) forbid > usage of '/' in the name. In such case we can allow a '.' or whatever > else, so that it's not considered as a directory. I do note that qemuDomainSnapshotCreateXML has a check for '/' in the name and disallows '.' as name[0]. It took a little bit to find, virDomainDefPostParseCheckFeatures is the domain mechanism.... > > In case of the storage driver I think we can ban '/' accross all drivers > and also in the parser, since storage pool containing an '/' probably > would vanish after VM restart and/or fail to be created for other > reasons than validation. ...and virStoragePoolDefParseXML already has a check for not allowing '/' in the name. > > Anyways, you need to change the validation regex and add the check to > reject slashes. > So, IIUC it's at least adding a '/' after the ^ in storagecommon.rng. I validated that works using the xmllint command that virt-xml-validate generates. Do you think virDomainDiskDefParseValidate should add a specific check that if disk->src->pool doesn't have '/'? Even if it did it wouldn't match anything since there'd be no pool with a '/'. IDC, I can add it, but just figured I'd get an opinion first.