psql with GSS can crash

On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek.Kotala@sun.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@%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.Kotala@sun.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@%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.Kotala@sun.com>:

Magnus Hagander píše v čt 25. 02. 2010 v 15:17 +0100:

On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek.Kotala@sun.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@%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.Kotala@sun.com>:

Magnus Hagander píše v čt 25. 02. 2010 v 15:17 +0100:

On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek.Kotala@sun.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@%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.Kotala@sun.com>:

Magnus Hagander píše v po 01. 03. 2010 v 16:55 +0100:

2010/3/1 Zdenek Kotala <Zdenek.Kotala@sun.com>:

Magnus Hagander píše v čt 25. 02. 2010 v 15:17 +0100:

On Thu, Feb 25, 2010 at 15:04, Zdenek Kotala <Zdenek.Kotala@sun.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@%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/