psql with GSS can crash

Hi all,

I got following stack:

fffffd7ffed14b70 strlen () + 40
fffffd7ffed71665 snprintf () + e5
fffffd7fff36d088 pg_GSS_startup () + 88
fffffd7fff36d43a pg_fe_sendauth () + 15a
fffffd7fff36e557 PQconnectPoll () + 3b7
fffffd7fff36e152 connectDBComplete () + a2
fffffd7fff36dc32 PQsetdbLogin () + 1b2
000000000041e96d main () + 30d
000000000041302c ???????? ()

It seems that connection is not fully configured and krbsrvname or
pghost is not filled. Following code in fe-auth.c pg_GSS_startup()
causes a crash:

440 maxlen = NI_MAXHOST + strlen(conn->krbsrvname) + 2;
441 temp_gbuf.value = (char *) malloc(maxlen);
442 snprintf(temp_gbuf.value, maxlen, "%s(at)%s",
443 conn->krbsrvname, conn->pghost);
444 temp_gbuf.length = strlen(temp_gbuf.value);

And following code in fe-connect.c fillPGconn() fill NULL value.

571 tmp = conninfo_getval(connOptions, "krbsrvname");
572 conn->krbsrvname = tmp ? strdup(tmp) : NULL;

I think that pg_GSS_startup should sanity the input.

Zdenek

On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com> wrote:
> Hi all,
>
> I got following stack:
>
>  fffffd7ffed14b70 strlen () + 40
>  fffffd7ffed71665 snprintf () + e5
>  fffffd7fff36d088 pg_GSS_startup () + 88
>  fffffd7fff36d43a pg_fe_sendauth () + 15a
>  fffffd7fff36e557 PQconnectPoll () + 3b7
>  fffffd7fff36e152 connectDBComplete () + a2
>  fffffd7fff36dc32 PQsetdbLogin () + 1b2
>  000000000041e96d main () + 30d
>  000000000041302c ???????? ()
>
> It seems that connection is not fully configured and krbsrvname or pghost is
> not filled. Following code in fe-auth.c pg_GSS_startup() causes a crash:
>
>    440         maxlen = NI_MAXHOST + strlen(conn->krbsrvname) + 2;
>    441         temp_gbuf.value = (char *) malloc(maxlen);
>    442         snprintf(temp_gbuf.value, maxlen, "%s(at)%s",
>    443                          conn->krbsrvname, conn->pghost);
>    444         temp_gbuf.length = strlen(temp_gbuf.value);
>
> And following code in fe-connect.c fillPGconn() fill NULL value.
>
>    571         tmp = conninfo_getval(connOptions, "krbsrvname");
>    572         conn->krbsrvname = tmp ? strdup(tmp) : NULL;
>
> I think that pg_GSS_startup should sanity the input.

How did you get NULL in there? :-)
There's a default set for that one that's PG_KRB_SRVNAM, so it really
should never come out as NULL, I think...

As for pghost, that certainly seems to be a bug. We check that one in
krb5 and SSPI, but for some reason we seem to be missing it in GSSAPI.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/

Magnus Hagander píše v čt 25. 02. 2010 v 15:17 +0100:
> On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com> wrote:
> > Hi all,
> >
> > I got following stack:
> >
> > fffffd7ffed14b70 strlen () + 40
> > fffffd7ffed71665 snprintf () + e5
> > fffffd7fff36d088 pg_GSS_startup () + 88
> > fffffd7fff36d43a pg_fe_sendauth () + 15a
> > fffffd7fff36e557 PQconnectPoll () + 3b7
> > fffffd7fff36e152 connectDBComplete () + a2
> > fffffd7fff36dc32 PQsetdbLogin () + 1b2
> > 000000000041e96d main () + 30d
> > 000000000041302c ???????? ()
> >
> > It seems that connection is not fully configured and krbsrvname or pghost is
> > not filled. Following code in fe-auth.c pg_GSS_startup() causes a crash:
> >
> > 440 maxlen = NI_MAXHOST + strlen(conn->krbsrvname) + 2;
> > 441 temp_gbuf.value = (char *) malloc(maxlen);
> > 442 snprintf(temp_gbuf.value, maxlen, "%s(at)%s",
> > 443 conn->krbsrvname, conn->pghost);
> > 444 temp_gbuf.length = strlen(temp_gbuf.value);
> >
> > And following code in fe-connect.c fillPGconn() fill NULL value.
> >
> > 571 tmp = conninfo_getval(connOptions, "krbsrvname");
> > 572 conn->krbsrvname = tmp ? strdup(tmp) : NULL;
> >
> > I think that pg_GSS_startup should sanity the input.
>
> How did you get NULL in there? :-)
> There's a default set for that one that's PG_KRB_SRVNAM, so it really
> should never come out as NULL, I think...

Yeah, you are right. conn->krbsrvname is "postgres" and conn->pghost is
null

> As for pghost, that certainly seems to be a bug. We check that one in
> krb5 and SSPI, but for some reason we seem to be missing it in GSSAPI.

Yes. The check should be in GSSAPI too.

However what I see in pg_hba.conf is following line:

local all all gss

Gss is used on local unix socket which probably cause a problem that
conn->pghost is not filled when psql tries to connect.

thanks Zdenek

Zdenek

2010/3/1 Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com>:
> Magnus Hagander píše v čt 25. 02. 2010 v 15:17 +0100:
>> On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com> wrote:
>> > Hi all,
>> >
>> > I got following stack:
>> >
>> >  fffffd7ffed14b70 strlen () + 40
>> >  fffffd7ffed71665 snprintf () + e5
>> >  fffffd7fff36d088 pg_GSS_startup () + 88
>> >  fffffd7fff36d43a pg_fe_sendauth () + 15a
>> >  fffffd7fff36e557 PQconnectPoll () + 3b7
>> >  fffffd7fff36e152 connectDBComplete () + a2
>> >  fffffd7fff36dc32 PQsetdbLogin () + 1b2
>> >  000000000041e96d main () + 30d
>> >  000000000041302c ???????? ()
>> >
>> > It seems that connection is not fully configured and krbsrvname or pghost is
>> > not filled. Following code in fe-auth.c pg_GSS_startup() causes a crash:
>> >
>> >    440         maxlen = NI_MAXHOST + strlen(conn->krbsrvname) + 2;
>> >    441         temp_gbuf.value = (char *) malloc(maxlen);
>> >    442         snprintf(temp_gbuf.value, maxlen, "%s(at)%s",
>> >    443                          conn->krbsrvname, conn->pghost);
>> >    444         temp_gbuf.length = strlen(temp_gbuf.value);
>> >
>> > And following code in fe-connect.c fillPGconn() fill NULL value.
>> >
>> >    571         tmp = conninfo_getval(connOptions, "krbsrvname");
>> >    572         conn->krbsrvname = tmp ? strdup(tmp) : NULL;
>> >
>> > I think that pg_GSS_startup should sanity the input.
>>
>> How did you get NULL in there? :-)
>> There's a default set for that one that's PG_KRB_SRVNAM, so it really
>> should never come out as NULL, I think...
>
> Yeah, you are right. conn->krbsrvname is "postgres" and conn->pghost is
> null

Ah, good. We should defentd against that then.

>> As for pghost, that certainly seems to be a bug. We check that one in
>> krb5 and SSPI, but for some reason we seem to be missing it in GSSAPI.
>
> Yes. The check should be in GSSAPI too.
>
> However what I see in pg_hba.conf is following line:
>
> local   all         all                               gss
>
> Gss is used on local unix socket which probably cause a problem that
> conn->pghost is not filled when psql tries to connect.

So there are really two errors - because we should disallow that.

See attached patch - can you confirm it removes the crash with just
the client side applied, and then that it properly rejects GSS with
the server side applied as well?

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/

Magnus Hagander píše v po 01. 03. 2010 v 16:55 +0100:
> 2010/3/1 Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com>:
> > Magnus Hagander píše v čt 25. 02. 2010 v 15:17 +0100:
> >> On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com> wrote:
> >> > Hi all,
> >> >
> >> > I got following stack:
> >> >
> >> > fffffd7ffed14b70 strlen () + 40
> >> > fffffd7ffed71665 snprintf () + e5
> >> > fffffd7fff36d088 pg_GSS_startup () + 88
> >> > fffffd7fff36d43a pg_fe_sendauth () + 15a
> >> > fffffd7fff36e557 PQconnectPoll () + 3b7
> >> > fffffd7fff36e152 connectDBComplete () + a2
> >> > fffffd7fff36dc32 PQsetdbLogin () + 1b2
> >> > 000000000041e96d main () + 30d
> >> > 000000000041302c ???????? ()
> >> >
> >> > It seems that connection is not fully configured and krbsrvname or pghost is
> >> > not filled. Following code in fe-auth.c pg_GSS_startup() causes a crash:
> >> >
> >> > 440 maxlen = NI_MAXHOST + strlen(conn->krbsrvname) + 2;
> >> > 441 temp_gbuf.value = (char *) malloc(maxlen);
> >> > 442 snprintf(temp_gbuf.value, maxlen, "%s(at)%s",
> >> > 443 conn->krbsrvname, conn->pghost);
> >> > 444 temp_gbuf.length = strlen(temp_gbuf.value);
> >> >
> >> > And following code in fe-connect.c fillPGconn() fill NULL value.
> >> >
> >> > 571 tmp = conninfo_getval(connOptions, "krbsrvname");
> >> > 572 conn->krbsrvname = tmp ? strdup(tmp) : NULL;
> >> >
> >> > I think that pg_GSS_startup should sanity the input.
> >>
> >> How did you get NULL in there? :-)
> >> There's a default set for that one that's PG_KRB_SRVNAM, so it really
> >> should never come out as NULL, I think...
> >
> > Yeah, you are right. conn->krbsrvname is "postgres" and conn->pghost is
> > null
>
> Ah, good. We should defentd against that then.
>
>
> >> As for pghost, that certainly seems to be a bug. We check that one in
> >> krb5 and SSPI, but for some reason we seem to be missing it in GSSAPI.
> >
> > Yes. The check should be in GSSAPI too.
> >
> > However what I see in pg_hba.conf is following line:
> >
> > local all all gss
> >
> > Gss is used on local unix socket which probably cause a problem that
> > conn->pghost is not filled when psql tries to connect.
>
> So there are really two errors - because we should disallow that.
>
> See attached patch - can you confirm it removes the crash with just
> the client side applied, and then that it properly rejects GSS with
> the server side applied as well?

I tested it, but I cannot reproduce crash because I cannot setup illegal
combination now ;-). I think it is OK.

Thanks Zdenek

2010/3/7 Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com>:
> Magnus Hagander píše v po 01. 03. 2010 v 16:55 +0100:
>> 2010/3/1 Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com>:
>> > Magnus Hagander píše v čt 25. 02. 2010 v 15:17 +0100:
>> >> On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek(dot)Kotala(at)sun(dot)com> wrote:
>> >> > Hi all,
>> >> >
>> >> > I got following stack:
>> >> >
>> >> >  fffffd7ffed14b70 strlen () + 40
>> >> >  fffffd7ffed71665 snprintf () + e5
>> >> >  fffffd7fff36d088 pg_GSS_startup () + 88
>> >> >  fffffd7fff36d43a pg_fe_sendauth () + 15a
>> >> >  fffffd7fff36e557 PQconnectPoll () + 3b7
>> >> >  fffffd7fff36e152 connectDBComplete () + a2
>> >> >  fffffd7fff36dc32 PQsetdbLogin () + 1b2
>> >> >  000000000041e96d main () + 30d
>> >> >  000000000041302c ???????? ()
>> >> >
>> >> > It seems that connection is not fully configured and krbsrvname or pghost is
>> >> > not filled. Following code in fe-auth.c pg_GSS_startup() causes a crash:
>> >> >
>> >> >    440         maxlen = NI_MAXHOST + strlen(conn->krbsrvname) + 2;
>> >> >    441         temp_gbuf.value = (char *) malloc(maxlen);
>> >> >    442         snprintf(temp_gbuf.value, maxlen, "%s(at)%s",
>> >> >    443                          conn->krbsrvname, conn->pghost);
>> >> >    444         temp_gbuf.length = strlen(temp_gbuf.value);
>> >> >
>> >> > And following code in fe-connect.c fillPGconn() fill NULL value.
>> >> >
>> >> >    571         tmp = conninfo_getval(connOptions, "krbsrvname");
>> >> >    572         conn->krbsrvname = tmp ? strdup(tmp) : NULL;
>> >> >
>> >> > I think that pg_GSS_startup should sanity the input.
>> >>
>> >> How did you get NULL in there? :-)
>> >> There's a default set for that one that's PG_KRB_SRVNAM, so it really
>> >> should never come out as NULL, I think...
>> >
>> > Yeah, you are right. conn->krbsrvname is "postgres" and conn->pghost is
>> > null
>>
>> Ah, good. We should defentd against that then.
>>
>>
>> >> As for pghost, that certainly seems to be a bug. We check that one in
>> >> krb5 and SSPI, but for some reason we seem to be missing it in GSSAPI.
>> >
>> > Yes. The check should be in GSSAPI too.
>> >
>> > However what I see in pg_hba.conf is following line:
>> >
>> > local   all         all                               gss
>> >
>> > Gss is used on local unix socket which probably cause a problem that
>> > conn->pghost is not filled when psql tries to connect.
>>
>> So there are really two errors - because we should disallow that.
>>
>> See attached patch - can you confirm it removes the crash with just
>> the client side applied, and then that it properly rejects GSS with
>> the server side applied as well?
>
> I tested it, but I cannot reproduce crash because I cannot setup illegal
> combination now ;-). I think it is OK.

Ok, thanks for testing. I've been unable to break it in my testing as
well so - applied, and back-patched.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/