[libvirt] [PATCH 6/7] security_dac: compute supplemental groups before fork

[Cole Robinson]

On 07/23/2013 11:03 AM, Eric Blake wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=964358
> 
> Commit 75c1256 states that virGetGroupList must not be called
> between fork and exec, then commit ee777e99 promptly violated
> that for lxc's use of virSecurityManagerSetProcessLabel.  Hoist
> the supplemental group detection to the time that the security
> manager needs to fork.  Qemu is safe, as it uses
> virSecurityManagerSetChildProcessLabel which in turn uses
> virCommand to determine supplemental groups.
> 
> This does not fix the fact that virSecurityManagerSetProcessLabel
> calls virSecurityDACParseIds calls parseIds which eventually
> calls getpwnam_r, which also violates fork/exec async-signal-safe
> safety rules, but so far no one has complained of hitting
> deadlock in that case.
> 
> * src/security/security_dac.c (_virSecurityDACData): Track groups
> in private data.
> (virSecurityDACPreFork): New function, to set them.
> (virSecurityDACClose): Clean up new fields.
> (virSecurityDACGetIds): Alter signature.
> (virSecurityDACSetSecurityHostdevLabelHelper)
> (virSecurityDACSetChardevLabel, virSecurityDACSetProcessLabel)
> (virSecurityDACSetChildProcessLabel): Update callers.
> 
> Signed-off-by: Eric Blake <eblake at redhat.com>
> (cherry picked from commit 29fe5d745fbe207ec2415441d4807ae76be05974)
> 
> Conflicts:
> 	src/security/security_dac.c - virSecurityDACSetSecurityUSBLabel needed similar treatment; no virSecurityDACSetChildPrcessLabel

ACK

- Cole