Re: [libvirt] [PATCHv2 2/2] security_dac: compute supplemental groups before fork

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 is created. 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; --- src/security/security_dac.c | 63 +++++++++++++++++++++++++++++++-------------- 1 file changed, 44 insertions(+), 19 deletions(-) diff --git a/src/security/security_dac.c b/src/security/security_dac.c index 9b5eaa8..00d04bf 100644 --- a/src/security/security_dac.c +++ b/src/security/security_dac.c @@ -43,6 +43,8 @@ typedef virSecurityDACData *virSecurityDACDataPtr; struct _virSecurityDACData { uid_t user; gid_t group; + gid_t *groups; + int ngroups; bool dynamicOwnership; }; @@ -146,7 +148,8 @@ virSecurityDACParseIds(virDomainDefPtr def, uid_t *uidPtr, gid_t *gidPtr) static int virSecurityDACGetIds(virDomainDefPtr def, virSecurityDACDataPtr priv, - uid_t *uidPtr, gid_t *gidPtr) + uid_t *uidPtr, gid_t *gidPtr, + gid_t **groups, int *ngroups) { int ret; @@ -157,8 +160,13 @@ virSecurityDACGetIds(virDomainDefPtr def, virSecurityDACDataPtr priv, return -1; } - if ((ret = virSecurityDACParseIds(def, uidPtr, gidPtr)) <= 0) + if ((ret = virSecurityDACParseIds(def, uidPtr, gidPtr)) <= 0) { + if (groups) + *groups = NULL; + if (ngroups) + ngroups = 0;

return ret; + } if (!priv) { virReportError(VIR_ERR_INTERNAL_ERROR,