[libvirt] [PATCH 2/2] security: Add a new func use stat to get process DAC label

[Luyao Huang]

When use qemuProcessAttach to attach a qemu process, cannot
get a right DAC label. Add a new func to get process label
via stat func. Do not remove virDomainDefGetSecurityLabelDef
before try to use stat to get process DAC label, because
There are some other func call virSecurityDACGetProcessLabel.

Signed-off-by: Luyao Huang <lhuang at redhat.com>
---
 src/security/security_dac.c | 50 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 48 insertions(+), 2 deletions(-)

diff --git a/src/security/security_dac.c b/src/security/security_dac.c
index 85253af..2977f71 100644
--- a/src/security/security_dac.c
+++ b/src/security/security_dac.c
@@ -1237,17 +1237,63 @@ virSecurityDACReserveLabel(virSecurityManagerPtr mgr ATTRIBUTE_UNUSED,
 }
 
 static int
+virSecurityDACGetProcessLabelInternal(pid_t pid,
+                                      virSecurityLabelPtr seclabel)
+{
+    struct stat sb;
+    char *path = NULL;
+    char *label = NULL;
+    int ret = -1;
+
+    VIR_INFO("Getting DAC user and group on process '%d'", pid);
+
+    if (virAsprintf(&path, "/proc/%d", (int) pid) < 0)
+        goto cleanup;
+
+    if (stat(path, &sb) < 0)
+        goto cleanup;
+
+    if (virAsprintf(&label, "+%u:+%u",
+                    (unsigned int) sb.st_uid,
+                    (unsigned int) sb.st_gid) < 0)
+        goto cleanup;
+
+    if (virStrcpy(seclabel->label, label,VIR_SECURITY_LABEL_BUFLEN) == NULL)
+        goto cleanup;
+    ret = 0;
+
+cleanup:
+    VIR_FREE(path);
+    VIR_FREE(label);
+    return ret;
+}
+
+static int
 virSecurityDACGetProcessLabel(virSecurityManagerPtr mgr ATTRIBUTE_UNUSED,
                               virDomainDefPtr def,
-                              pid_t pid ATTRIBUTE_UNUSED,
+                              pid_t pid,
                               virSecurityLabelPtr seclabel)
 {
     virSecurityLabelDefPtr secdef =
         virDomainDefGetSecurityLabelDef(def, SECURITY_DAC_NAME);
 
-    if (!secdef || !seclabel)
+    if (!seclabel)
         return -1;
 
+    if (secdef == NULL) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("missing label for DAC security "
+                         "driver in domain %s"), def->name);
+
+        if (virSecurityDACGetProcessLabelInternal(pid, seclabel) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Cannot get process %d DAC label"),pid);
+            return -1;
+        }
+
+        return 0;
+    }
+
     if (secdef->label)
         ignore_value(virStrcpy(seclabel->label, secdef->label,
                                VIR_SECURITY_LABEL_BUFLEN));
-- 
1.8.3.1