[libvirt] [PATCH 2/8] qemuDomainBuildNamespace: Handle special file mount points
John Ferlan
jferlan at redhat.com
Tue Jun 27 21:47:41 UTC 2017
On 06/27/2017 05:37 PM, John Ferlan wrote:
>
>
> On 06/22/2017 12:18 PM, Michal Privoznik wrote:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1459592
>>
>> In 290a00e41d I've tried to fix the process of building a
>> qemu namespace when dealing with file mount points. What I
>> haven't realized then is that we might be dealing not with just
>> regular files but also special files (like sockets). Indeed, try
>> the following:
>>
>> 1) socat unix-listen:/tmp/soket stdio
>> 2) touch /dev/socket
>> 3) mount --bind /tmp/socket /dev/socket
>> 4) virsh start anyDomain
>>
>> Problem with my previous approach is that I wasn't creating the
>> temporary location (where mount points under /dev are moved) for
>> anything but directories and regular files.
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>> src/qemu/qemu_domain.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
>> index 8e7404da6..212717c80 100644
>> --- a/src/qemu/qemu_domain.c
>> +++ b/src/qemu/qemu_domain.c
>> @@ -8356,9 +8356,11 @@ qemuDomainBuildNamespace(virQEMUDriverConfigPtr cfg,
>> goto cleanup;
>> }
>>
>> - /* At this point, devMountsPath is either a regular file or a directory. */
>> + /* At this point, devMountsPath is either:
>> + * a file (regular or special), or
>> + * a directory. */
>> if ((S_ISDIR(sb.st_mode) && virFileMakePath(devMountsSavePath[i]) < 0) ||
>> - (S_ISREG(sb.st_mode) && virFileTouch(devMountsSavePath[i], sb.st_mode) < 0)) {
>> + (!S_ISDIR(sb.st_mode) && virFileTouch(devMountsSavePath[i], sb.st_mode) < 0)) {
>
> It would seem to me that this would open Pandora's box to all different
> types of things (BLK, CHR, FIFO, LNK, NAM, MPB, MPC, NWK) - some of
> which it may not be so popular to perform a touch on.
>
> I think you should keep it specific... Perhaps use the list from
> qemuDomainCreateDeviceRecursive:
>
> isReg = S_ISREG(sb.st_mode) || S_ISFIFO(sb.st_mode) ||
> S_ISSOCK(sb.st_mode);
>
> John
>
I guess it's obvious now that I've actually paged in patches 4-8 that I
used the same sandbox I'm reviewing in order to make this comment!
I think the same concern applies though...
John
> (FWIW: I used a cscope search on S_ISSOCK...)
>
>
>> virReportSystemError(errno,
>> _("Failed to create %s"),
>> devMountsSavePath[i]);
>>
>
> --
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