On Mon, 2014-04-14 at 11:48 -0400, Jeff Layton wrote:
> On Mon, 14 Apr 2014 11:07:37 -0400
> Steve Dickson <SteveD@xxxxxxxxxx> wrote:
>
> > Hey Jeff,
> >
> > Just a couple nit....
> >
> > On 04/10/2014 04:31 PM, Jeff Layton wrote:
> > > ...and pass it to the kernel in the downcall. Legacy kernels will just
> > > ignore the extra data, but with a proposed kernel patch the kernel will
> > > grab this info and use it to verify requests on the v4.0 callback
> > > channel.
> > >
> > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > > ---
> > > utils/gssd/gssd_proc.c | 39 ++++++++++++++++++++++++++++-----------
> > > 1 file changed, 28 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
> > > index 7387cce010cf..d95e39416c28 100644
> > > --- a/utils/gssd/gssd_proc.c
> > > +++ b/utils/gssd/gssd_proc.c
> > > @@ -77,6 +77,7 @@
> > > #include "context.h"
> > > #include "nfsrpc.h"
> > > #include "nfslib.h"
> > > +#include "gss_names.h"
> > >
> > > /*
> > > * pollarray:
> > > @@ -683,16 +684,19 @@ parse_enctypes(char *enctypes)
> > >
> > > static void
> > > do_downcall(int k5_fd, uid_t uid, struct authgss_private_data *pd,
> > > - gss_buffer_desc *context_token, OM_uint32 lifetime_rec)
> > > + gss_buffer_desc *context_token, OM_uint32 lifetime_rec,
> > > + gss_buffer_desc *acceptor)
> > > {
> > > char *buf = NULL, *p = NULL, *end = NULL;
> > > unsigned int timeout = context_timeout;
> > > unsigned int buf_size = 0;
> > >
> > > - printerr(1, "doing downcall lifetime_rec %u\n", lifetime_rec);
> > > + printerr(1, "doing downcall: lifetime_rec=%u acceptor=%.*s\n",
> > > + lifetime_rec, acceptor->length, acceptor->value);
> > > buf_size = sizeof(uid) + sizeof(timeout) + sizeof(pd->pd_seq_win) +
> > > sizeof(pd->pd_ctx_hndl.length) + pd->pd_ctx_hndl.length +
> > > - sizeof(context_token->length) + context_token->length;
> > > + sizeof(context_token->length) + context_token->length +
> > > + acceptor->length;
> > > p = buf = malloc(buf_size);
> > > if (!buf)
> > > goto out_err;
> > > @@ -707,6 +711,8 @@ do_downcall(int k5_fd, uid_t uid, struct authgss_private_data *pd,
> > > if (WRITE_BYTES(&p, end, pd->pd_seq_win)) goto out_err;
> > > if (write_buffer(&p, end, &pd->pd_ctx_hndl)) goto out_err;
> > > if (write_buffer(&p, end, context_token)) goto out_err;
> > > + if (acceptor->length > 0 &&
> > > + write_buffer(&p, end, acceptor)) goto out_err;
> > >
> > > if (write(k5_fd, buf, p - buf) < p - buf) goto out_err;
> > > free(buf);
> > > @@ -1034,6 +1040,9 @@ process_krb5_upcall(struct clnt_info *clp, uid_t uid, int fd, char *tgtname,
> > > gss_cred_id_t gss_cred;
> > > OM_uint32 maj_stat, min_stat, lifetime_rec;
> > > pid_t pid;
> > > + gss_name_t gacceptor;
> > > + gss_OID mech;
> > > + gss_buffer_desc acceptor = {0};
> > >
> > > pid = fork();
> > > switch(pid) {
> > > @@ -1174,15 +1183,22 @@ process_krb5_upcall(struct clnt_info *clp, uid_t uid, int fd, char *tgtname,
> > > goto out_return_error;
> > > }
> > >
> > > - /* Grab the context lifetime to pass to the kernel. lifetime_rec
> > > - * is set to zero on error */
> > Why get rid of this comment instead of updating it?
> >
>
> I suppose I could do that. Would you prefer I respin and update that
> comment instead?
>
> > > - maj_stat = gss_inquire_context(&min_stat, pd.pd_ctx, NULL, NULL,
> > > - &lifetime_rec, NULL, NULL, NULL, NULL);
> > > + maj_stat = gss_inquire_context(&min_stat, pd.pd_ctx, NULL, &gacceptor,
> > > + &lifetime_rec, &mech, NULL, NULL, NULL);
> > >
> > > - if (maj_stat)
> > > - printerr(1, "WARNING: Failed to inquire context for lifetme "
> > > - "maj_stat %u\n", maj_stat);
> > > + if (maj_stat != GSS_S_COMPLETE) {
> > > + printerr(1, "WARNING: Failed to inquire context "
> > > + "maj_stat (0x%x)\n", maj_stat);
> > > + } else {
> > > + get_hostbased_client_buffer(gacceptor, mech, &acceptor);
> > > + gss_release_name(&min_stat, &gacceptor);
> > > + }
> > >
> > > + /*
> > > + * The serialization can mean turning the ctx into a lucid context. If
> > > + * that happens then the original ctx is no longer valid, so we mustn't
> > > + * try to use if after this point.
> > I'm not sure what you are trying to say here...
> >
> > steved.
> >
>
> Just a semi-helpful context for posterity...
>
> On my initial attempt, I tried to change the code around to grab the
> lifetime and acceptor out of the context in do_downcall. That didn't
> work, because once you call serialize_context_for_kernel, the GSS
> context is turned into a "lucid context". At that point, things like
> gss_inquire_context no longer work on it.
>
> IOW, once you call serialize_context_for_kernel, you can't count on
> being able to do anything useful with pd.pd_ctx at all.
This is on purpose, when you export the lucid context, the original
context is destroyed, this is to avoid having 2 parties with a context
for the same connection as the sequence numbers would get messed up and
communication fail if 2 parties tried to use them at the same time
anyway.
Simo.
--
Simo Sorce * Red Hat, Inc * New York
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