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

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(a)redhat.com&gt; (cherry picked from commit 29fe5d745fbe207ec2415441d4807ae76be05974) Conflicts: src/security/security_dac.c - virSecurityDACSetSecurityUSBLabel needed similar treatment; no virSecurityDACSetChildPrcessLabel