Re: [libvirt] [PATCH 2/3] util: virfile: Clarify setuid usage for virFileRemove
On 03/09/2016 12:38 PM, Cole Robinson wrote:
Break these checks out into their own function, and clearly document
each one. This shouldn't change behavior
---
src/util/virfile.c | 33 +++++++++++++++++++++++++++------
1 file changed, 27 insertions(+), 6 deletions(-)
diff --git a/src/util/virfile.c b/src/util/virfile.c
index f45e18f..cea2674 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -2314,6 +2314,32 @@ virFileOpenAs(const char *path, int openflags, mode_t mode,
}
+/* virFileRemoveNeedsSetuid:
+ * @uid: file uid to check
+ * @gid: file gid to check
+ *
+ * Return true if we should use setuid/setgid before deleting a file
+ * owned by the passed uid/gid pair. Needed for NFS with root-squash
+ */
+static bool
+virFileRemoveNeedsSetuid(uid_t uid, gid_t gid)
+{
+ /* If running unprivileged, setuid isn't going to work */
+ if (geteuid() != 0)
+ return false;
+
+ /* uid/gid weren'd specified */
weren't
ACK - with the nit fixed... The rest is me typing out my thoughts...
John
+ if ((uid == (uid_t) -1) && (gid == (gid_t) -1))
+ return false;
This "should" only happen as failure path of
virStorageBackendCreateExecCommand when uid/gid not provided in the XML.
The virStorageBackendCreateRaw failure path expects creation to have
occurred where virFileOpenAs would have set the owner/mode due to the
operation_flags setting.
+
+ /* already running as proper uid/gid */
+ if (uid == geteuid() && gid == getegid())
+ return false;
+
If the XML provided uid/gid and it's root - that's what we want
+ return true;
+}
+
+
/* virFileRemove:
* @path: file to unlink or directory to remove
* @uid: uid that was used to create the file (not required)
@@ -2335,12 +2361,7 @@ virFileRemove(const char *path,
gid_t *groups;
int ngroups;
- /* If not running as root or if a non explicit uid/gid was being used for
- * the file/volume or the explicit uid/gid matches, then use unlink directly
- */
- if ((geteuid() != 0) ||
- ((uid == (uid_t) -1) && (gid == (gid_t) -1)) ||
- (uid == geteuid() && gid == getegid())) {
+ if (!virFileRemoveNeedsSetuid(uid, gid)) {
if (virFileIsDir(path))
return rmdir(path);
else