samba - Dec 2020 - Strange logs: check_usershare_stat: file /var/lib/samba/usershares/ owned by uid 0 is not a regular file

On Wed, Dec 02, 2020 at 09:54:16AM +0000, Rowland penny via samba wrote:
>OK, I have realised why this is happening, but not how (or is that 
>how, but not why ?)
>
>I set 'profilePath' to '//raspberrypi/profiles' in my AD
object,
>unfortunately the 'raspberrypi' that is running now isn't the
same one
>that was running when I set it and it doesn't have a profiles share. 
>The question has to be, is this a Samba problem, or is it a Windows 
>problem ? To me, it seems that Windows looks for the profile and 
>having not found it, searches on 'raspberrypi' for it, so should 
>Windows be doing this and should Samba be allowing this ?
We can't control clients asking for anything unfortunately.

OK, I see the problem. There are two paths into process_usershare_file.
One is the directory scanner. But the second one is if a client asks for an
unknown
share and usershares are enabled it calls:

load_usershare_service()

- we end up in process_usershare_file() and go into the path:

         if (sys_lstat(fname, &lsbuf, false) != 0) {
                 DEBUG(0,("process_usershare_file: stat of %s failed.
%s\n",
                         fname, strerror(errno) ));
                 goto out;
         }

A debug level zero is a valid thing to do if we're processing a name
from the directory scanner, but not from an unknown share.

Fix is to bump this debug to DBG_INFO. If there really was
a problem and we're coming in from the directory scanner,
then we'll end up in check_usershare_stat() and the admin
will get notified that way.

Rowland, can you log a bug and I'll create a patch MR
for this ?

Thanks,

Jeremy.

On Wed, Dec 02, 2020 at 09:46:23AM -0800, Jeremy Allison via samba
wrote:
>
>Rowland, can you log a bug and I'll create a patch MR
>for this ?
Can you test the following patch before we do so ?
I think it'll quiet down the log-spam.

diff --git a/source3/param/loadparm.c b/source3/param/loadparm.c
index fbeed6782ad..3de22b350f1 100644
--- a/source3/param/loadparm.c
+++ b/source3/param/loadparm.c
@@ -3424,6 +3424,11 @@ static int process_usershare_file(const char *dir_name,
const char *file_name, i
            open and fstat. Ensure this isn't a symlink link. */
  
         if (sys_lstat(fname, &lsbuf, false) != 0) {
+               if (errno == ENOENT) {
+                       /* Unknown share requested. Just ignore. */
+                       goto out;
+               }
+               /* Only log messages for meaningful problems. */
                 DEBUG(0,("process_usershare_file: stat of %s failed.
%s\n",
                         fname, strerror(errno) ));
                 goto out;
@@ -3629,6 +3634,11 @@ int load_usershare_service(const char *servicename)
         int max_user_shares = Globals.usershare_max_shares;
         int snum_template = -1;
  
+       if (servicename[0] == '\0') {
+               /* Invalid service name. */
+               return -1;
+       }
+
         if (*usersharepath == 0 ||  max_user_shares == 0) {
                 return -1;
         }