Re: Unable to find pw entry for uid

["Aurélien Aptel" <aaptel@suse.com>]

Hi Calvin,

Calvin Chiang <calvin.chiang@gmail.com> writes:
> Now oddly the strerror(errno) is actually returning SUCCESS
> But the pw = getpwuid(uid); is failing.
> Getpwuid(uid) is calling nss.

...

> and the output from the sssd_nss.log is:

...

>     (Mon May  3 13:05:12 2021) [sssd[nss]]
> [cache_req_search_ncache_filter] (0x0400): CR #114: Filtering out
> results by negative cache
>
>     (Mon May  3 13:05:12 2021) [sssd[nss]] [sss_ncache_check_str]
> (0x2000): Checking negative cache for
> [NCE/USER/cyberloop.local/alice@cyberloop.local]
>
>     (Mon May  3 13:05:12 2021) [sssd[nss]]
> [cache_req_create_and_add_result] (0x0400): CR #114: Found 1 entries
> in domain cyberloop.local

I don't know much about sssd but if it's finding 1 entry in the
*negative* cache that means it knows it doesn't exist. (I'm assuming
negative cache means cache of queries that have no results)

That being said I've had issue with getpwuid() before that were solved
by updating glibc. Could be totally unrelated to your problem though.

You should try to attach gdb to the cifs.upcall process. You can do this
by adding

    syslog(LOG_ERR, "my pid is %d", getpid());
    sleep(5);

in cifs.upcall.c before the getpwuid() call. Then try triggering the
mount. It should block because of the sleep(). In a different terminal,
look at your system journal for the PID, and run gdb -p $pid. From there
you will be able to step into the getpwuid (glibc), nss, sss, calls.

If your linux distribution has a debug symbol server setup for gdb to
use, gdb will dynamically fetch symbols and source code on the
fly. Otherwise you will probably need to install debug and source
packages for glibc, nss and sssd packages to be able to see function
names and source code in gdb.

Cheers,
-- 
Aurélien Aptel / SUSE Labs Samba Team
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