On Tue, 2013-10-22 at 10:04 -0400, Weston Andros Adamson wrote:
> Call gss_inquire_cred after gssd_acquire_krb5_cred check for expired
> credentials.
>
> This fixes a recent regression (since 302de786930a2c533068f9d8909a817b40f07c32)
> that causes the user's ticket cache to grow unbounded with expired service
> tickets when the user's credentials expire.
>
> To reproduce this issue:
>
> - mount kerberos nfs export
> - kinit for a short lifetime (ie "kinit -l 1m")
> - run a job that opens a file and writes for more than the lifetime
> - run klist a few times after expiry and see the list grow, ie:
>
> Ticket cache: DIR::/run/user/1749600001/krb5cc/tktYmpGlX
> Default principal: dros@xxxxxxxxxxx
>
> Valid starting Expires Service principal
> 10/21/2013 15:39:38 10/21/2013 15:40:35 krbtgt/APIKIA.FAKE@xxxxxxxxxxx
> 10/21/2013 15:39:40 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:35 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:36 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:37 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:37 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:38 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:38 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:39 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:39 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:39 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:39 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:40 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:40 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:41 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:41 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:42 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:42 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
> 10/21/2013 15:40:42 10/21/2013 15:40:35 nfs/zero.apikia.fake@xxxxxxxxxxx
>
> Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxx>
> ---
> utils/gssd/krb5_util.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/utils/gssd/krb5_util.c b/utils/gssd/krb5_util.c
> index c6e52fd..ec5db83 100644
> --- a/utils/gssd/krb5_util.c
> +++ b/utils/gssd/krb5_util.c
> @@ -1405,6 +1405,13 @@ gssd_acquire_user_cred(uid_t uid, gss_cred_id_t *gss_cred)
>
> ret = gssd_acquire_krb5_cred(name, gss_cred);
>
> + /* force validation of cred to check for expiry */
> + if (ret == 0) {
> + if (gss_inquire_cred(min_stat, gss_cred, NULL, NULL,
> + NULL, NULL) != GSS_S_COMPLETE)
> + ret = -1;
> + }
> +
> maj_stat = gss_release_name(&min_stat, &name);
> return ret;
> }
A good start, but given you are inquiring creds, then I think it would
totally make sense to pass in a uint32_t for the 4th argument
(lifetime), and check if there is "enough".
For example, if it returns a lifetime of 1 second should we continue ?
There is a fat chance that it will fail later on.
I think we should at least log it if the credential we are trying to use
turns out to be really close to expiring, no ? It may save some gray
hairs to server administrators trying to find out what is going wrong
(like it happened to you :)
Simo.
--
Simo Sorce * Red Hat, Inc * New York
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