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Re: [libvirt] [PATCH] security: also parse user/group names instead of just IDs for DAC labels



On 09/19/12 23:32, Marcelo Cerri wrote:
The DAC driver is missing parsing of group and user names for DAC labels
and currently just parses uid and gid. This patch extends it to support
names, so the following security label definition is now valid:

   <seclabel type='static' model='dac' relabel='yes'>
       <label>qemu:qemu</label>
       <imagelabel>qemu:qemu</imagelabel>
   </seclabel>
---
  src/security/security_dac.c | 49 ++++++++++++++++++++++++++++++++++++---------
  1 file changed, 40 insertions(+), 9 deletions(-)

diff --git a/src/security/security_dac.c b/src/security/security_dac.c
index be65d6e..7e11e31 100644
--- a/src/security/security_dac.c
+++ b/src/security/security_dac.c
@@ -66,28 +66,59 @@ void virSecurityDACSetDynamicOwnership(virSecurityManagerPtr mgr,
  }

  static
+int parseId(const char *str, unsigned int *id)
+{
+    char *endptr = NULL;
+
+    if (str == NULL || id == NULL)
+        return -1;
+
+    if (virStrToLong_ui(str, &endptr, 10, id) || endptr != NULL)

After successful parse "endptr" will point to the '\0' byte at the end of the string always thiggering this condition. Call virStrToLong_ui with NULL instead of endptr and the wrapper will do the expected thing.

+        return -1;
+
+    return 0;
+}
+
+static
  int parseIds(const char *label, uid_t *uidPtr, gid_t *gidPtr)
  {
+    int rc = -1;
      unsigned int theuid;
      unsigned int thegid;
-    char *endptr = NULL;
+    char *sep = NULL;
+    char *tmp_label = NULL;

      if (label == NULL)
-        return -1;
+        goto done;

-    if (virStrToLong_ui(label, &endptr, 10, &theuid) ||
-        endptr == NULL || *endptr != ':') {
-        return -1;
-    }
+    tmp_label = strdup(label);
+    if (tmp_label == NULL)

You need to raise an OOM error with virReportOOMError() here even if it's masked by the upper layer. This error gets recorded to the logs and might help debugging.

I'm thinking if it's worth reporting other errors in this function as they get masked. They might be useful for debugging purposes even if they don't get propagated to the user.

+        goto done;

-    if (virStrToLong_ui(endptr + 1, NULL, 10, &thegid))
-        return -1;
+    sep = strchr(tmp_label, ':');
+    if (sep == NULL)
+        goto done;
+    *sep = '\0';
+
+    if (virGetUserID(tmp_label, &theuid) < 0 &&
+        parseId(tmp_label, &theuid) < 0)
+        goto done;
+
+    if (virGetGroupID(sep + 1, &thegid) < 0 &&
+        parseId(sep + 1, &thegid) < 0)
+        goto done;

      if (uidPtr)
          *uidPtr = theuid;
      if (gidPtr)
          *gidPtr = thegid;
-    return 0;
+
+    rc = 0;
+
+done:

I'd rename this label to "cleanup" for consistency with other libvirt code.

+    VIR_FREE(tmp_label);
+
+    return rc;
  }

  /* returns 1 if label isn't found, 0 on success, -1 on error */


Peter


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