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Date:   Thu, 17 Oct 2019 11:26:28 -0400
From:   Scott Mayhew <smayhew@redhat.com>
To:     steved@redhat.com
Cc:     linux-nfs@vger.kernel.org
Subject: Re: [nfs-utils PATCH v3] gssd: daemonize earlier
Message-ID: <20191017152628.GA5017@coeurl.usersys.redhat.com.nfsv4bat.org>
References: <20191017150844.21045-1-smayhew@redhat.com>
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Note this is v1 patch.  I forgot to check my git config before creating
the patch :)

-Scott

On Thu, 17 Oct 2019, Scott Mayhew wrote:

> daemon_init() calls closeall() which closes all fd's >= 4.  This causes
> rpc.gssd to fail when it's configured to use the gssproxy interposer
> plugin (via "use-gss-proxy=1" in nfs.conf or GSS_USE_PROXY="yes" in the
> environment) *and* libtirpc debugging is enabled (i.e. at least one
> "-r" on the command line):
> 
> 1. During startup if rpc debugging is enabled then libtirpc_set_debug()
>    is called, which calls openlog() which consumes fd 3.
> 2. If the gssproxy interposer plugin is enabled then when
>    gssd_check_mechs() is called, a socket is created (fd 4) and
>    connected to /var/lib/gssproxy/default.sock.  The fd is stored
>    internally in a struct gpm_ctx.
> 3. daemon_init() runs and closes all fd's >= 4.
> 4. event_init() runs which calls epoll_create() which returns an epoll
>    fd of 4.
> 5. Later when handling an upcall, gssd calls gssd_acquire_krb5_cred()
>    which winds up closing the gpm_ctx->fd which was 4.
> 6. event_dispatch() calls epoll_wait() with epfd=4, and -EBADF is
>    returned.  gssd logs the message ""ERROR: event_dispatch() returned!"
>    and exits.
> 
> The solution is to call daemon_init() earlier.
> 
> Signed-off-by: Scott Mayhew <smayhew@redhat.com>
> ---
>  utils/gssd/gssd.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/utils/gssd/gssd.c b/utils/gssd/gssd.c
> index 19ad4da..c38dedb 100644
> --- a/utils/gssd/gssd.c
> +++ b/utils/gssd/gssd.c
> @@ -1020,11 +1020,11 @@ main(int argc, char *argv[])
>  			    "support setting debug levels\n");
>  #endif
>  
> +	daemon_init(fg);
> +
>  	if (gssd_check_mechs() != 0)
>  		errx(1, "Problem with gssapi library");
>  
> -	daemon_init(fg);
> -
>  	event_init();
>  
>  	pipefs_dir = opendir(pipefs_path);
> -- 
> 2.17.2
>