[SSSD] [PATCH] Every time return directory for krb5 cache collection.

Lukas Slebodnik lslebodn at redhat.com
Wed Jun 26 08:23:59 UTC 2013


On (25/06/13 11:40), Jakub Hrozek wrote:
>On Mon, Jun 24, 2013 at 10:54:30PM +0200, Lukas Slebodnik wrote:
>> On (24/06/13 22:06), Jakub Hrozek wrote:
>> >On Sat, Jun 22, 2013 at 01:55:51PM +0200, Lukas Slebodnik wrote:
>> >> On (21/06/13 20:45), Jakub Hrozek wrote:
>> >> >On Thu, Jun 20, 2013 at 11:11:17AM +0200, Lukas Slebodnik wrote:
>> >> >> Rewritten patches are attached.
>> >> >> 
>> >> >> LS
>> >> >
>> >> >Two nitpicks:
>> >> >
>> >> >> +static char * get_ccache_name_by_principal(TALLOC_CTX *mem_ctx,
>> >> >> +                                           krb5_context ctx,
>> >> >> +                                           krb5_principal principal,
>> >> >> +                                           const char *ccname)
>> >> >> +{
>> >> >> +    krb5_error_code kerr;
>> >> >> +    krb5_ccache tmp_cc = NULL;
>> >> >> +    char *tmp_ccname = NULL;
>> >> >> +    char *ret_ccname = NULL;
>> >> >> +
>> >> >> +    kerr = krb5_cc_set_default_name(ctx, ccname);
>> >> >> +    if (kerr != 0) {
>> >> >> +        KRB5_CHILD_DEBUG(SSSDBG_MINOR_FAILURE, kerr);
>> >> >> +        return NULL;
>> >> >> +    }
>> >> >> +
>> >> >> +    kerr = krb5_cc_cache_match(ctx, principal, &tmp_cc);
>> >> >> +    if (kerr != 0) {
>> >> >> +        KRB5_CHILD_DEBUG(SSSDBG_TRACE_INTERNAL, kerr);
>> >> >> +        return NULL;
>> >> >> +    }
>> >> >> +
>> >> >> +    kerr = krb5_cc_get_full_name(ctx, tmp_cc, &tmp_ccname);
>> >> >> +    if (kerr !=0) {
>> >> >> +        KRB5_CHILD_DEBUG(SSSDBG_MINOR_FAILURE, kerr);
>> >> >> +    }
>> >> >> +
>> >> >> +    ret_ccname = talloc_strdup(mem_ctx, tmp_ccname);
>> >> >> +    if (ret_ccname == NULL) {
>> >> >> +        DEBUG(SSSDBG_OP_FAILURE, ("talloc_strdup failed (ENOMEM).\n"));
>> >> >> +    }
>> >> >> +
>> >> >> +done:
>> >> >
>> >> >This done label is unused and GCC emits a warning over that. It should
>> >> >be used if krb5_cc_get_full_name() fails.
>> >> >
>> >> >> +    if (tmp_cc != NULL) {
>> >> >> +        kerr = krb5_cc_close(ctx, tmp_cc);
>> >> >> +        if (kerr != 0) {
>> >> >> +            KRB5_CHILD_DEBUG(SSSDBG_MINOR_FAILURE, kerr);
>> >> >> +        }
>> >> >> +    }
>> >> >> +    krb5_free_string(ctx, tmp_ccname);
>> >> >> +
>> >> >> +    return ret_ccname;
>> >> >> +}
>> >> >> +
>> >> >
>> >> >
>> >> >> 
>> >> >> +    kerr = krb5_unparse_name(ctx, princ, &full_name);
>> >> >> +    if (kerr !=0) {
>> >> >> +        KRB5_CHILD_DEBUG(SSSDBG_TRACE_INTERNAL, kerr);
>> >> >> +        goto done;
>> >> >> +    }
>> >> >> +
>> >> >> +    if (0 == strcmp(default_full_name, full_name)) {
>> >> >> +        ret = true;
>> >> >> +    }
>> >> >> +
>> >> >
>> >> >If you're changing the other patch, can you also add DEBUG message here
>> >> >saying what has been compared?
>> >> >
>> >> >> +done:
>> >> >> +    if (default_cc != NULL) {
>> >> >> +        kerr = krb5_cc_close(ctx, default_cc);
>> >> >> +        if (kerr != 0) {
>> >> >> +            KRB5_CHILD_DEBUG(SSSDBG_OP_FAILURE, kerr);
>> >> >> +            goto done;
>> >> >> +        }
>> >> >> +    }
>> >> >> +
>> >> >> +    /* all functions can be safely called with NULL. */
>> >> >> +    krb5_free_principal(ctx, default_princ);
>> >> >> +    krb5_free_unparsed_name(ctx, default_full_name);
>> >> >> +    krb5_free_unparsed_name(ctx, full_name);
>> >> >> +
>> >> >> +    return ret;
>> >> >> +}
>> >> >
>> >> >So far I ran a number of tests against IPA. I should still check AD
>> >> >provider especially with enterprise principals to see if they still
>> >> >work. If they do I'll ack.
>> >> >
>> >> >But I will also file a ticket for 1.10.1 to move the checks to the
>> >> >backend so they are all done on one place as Sumit suggested earlier.
>> >> >
>> >> I removed checks in former updates. There left only mapping
>> >> from collection ccache (DIR:<cc_dir_name>) to ccache
>> >> (DIR::<cc_dir_name>/<ticket_name>)
>> >> 
>> >> I tried some modifications on backend side (with gdb), but I could not get an aim
>> >> 1. store collection ccache name stored in sysdb
>> >> 2. environment variable KRB5CCNAME also contains collection ccache name
>> >> 3. do not have more ccaches with same principal name
>> >> 
>> >> >I don't think it's necessary to delay 1.10.0 any longer for this issue,
>> >> >but it's the right thing to do eventually.
>> >> 
>> >> Updated patches are attached.
>> >> 
>> >> LS
>> >
>> >I still see two issues, sorry:
>> >
>> >1) The cc_residual_is_used check seems to be broken:
>> >
>> >[sssd[be[AD.EXAMPLE.COM]]] [cc_residual_is_used] (0x1000): User [1983201109]
>> >is still active, reusing ccache [/run/user/1983201109].
>> >[sssd[be[AD.EXAMPLE.COM]]] [cc_residual_is_used] (0x0200): Cache file
>> >[/run/user/1983201109/primary] does not exist, it will be recreated
>> >     ^^^^^^^^^^^^^^^^^
>> >  This path cannot exist, I think SSSD should be checking for
>> >  /run/user/1983201109/krb5cc/primary instead
>> >
>> >[sssd[be[AD.EXAMPLE.COM]]] [check_for_valid_tgt] (0x0020): krb5_cc_retrieve_cred failed.
>> >[sssd[be[AD.EXAMPLE.COM]]] [fo_resolve_service_send] (0x0100): Trying to resolve service 'AD'
>> >
>> >2) When using enterprise credentials, multiple logins always get a new
>> >ccache. I don't see this happening with origin/master, sorry.
>> I thought, that it is aim of cache collection to have separate ccache for
>> different logins.
>
>Yes, but these were two separate logins of the same principal. I've
>demonstrated the issue to Lukas in a VM to make sure we both see the
>problem.

I would like to describe situation, because I am not really sure, where is the
problem.

String "ptest\\@FOO.BAR at SSSD-AD.TEST" is sent to krb5_child with enterprise
principal. We have empty cache collection. New ccache is created (after login).
This new ccache has principal name "ptest at SSSD-AD.TEST"

Output from klist -l
#> Principal name                 Cache name
#> --------------                 ----------
#> ptest at SSSD-AD.TEST             DIR::/run/user/947005188/krb5cc/tktceNIlD

User decides to log on machine second time. Attribute ccacheFile has value
"DIR:/run/user/947005188/krb5cc/", therefore we need find ccache in collection.
With my patches, sssd uses function krb5_cc_cache_match to find ccache by
principal. krb5_cc_cache_match internally uses krb5_principal_compare_flags to
compare two principals and here is the problem

By default, krb5_principal_compare_flags is called with flags argument 0.
In this case following principals are compared

principal->data      principal->realm
------------------------------
ptest                SSSD-AD.TEST   //Principal obtained from existing ccache
ptest at FOO.BAR        SSSD-AD.TEST   //Principal created by parsing string

I tried to call krb5_principal_compare_flags with argument
flags = KRB5_PRINCIPAL_COMPARE_ENTERPRISE and in this case following principals
were compared.

principal->data      principal->realm
------------------------------
ptest                SSSD-AD.TEST   //Principal obtained from existing ccache
ptest                FOO.BAR        //Principal created by parsing string


This is a reason, why ccache can't be found in collection and
new ccache is created every time.

LS



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