From: Andy Adamson <andros@xxxxxxxxxx>
The kernel gss_cl_ctx stores the context lifetime in gc_expiry, set
by gssd in do_downcall() called by process_krb5_upcall(). The lifetime value is
currently not related at all to the Kerberos TGS lifetime. It is either
set to the value of gssd -t <timeout>, or to a kernel default of 3600
seconds.
Most of the time the gssd -t command line is not set, and a timeout value
of zero was sent to the kernel triggering the use of the 3600 second kernel
default timeout.
In order for the kernel to properly know when to renew a context, or to stop
buffering writes for a context about to expire, the gc_expiry value needs to
reflect the credential lifetime used to create the context.
Note that gss_inquire_cred returns the number of seconds for which the context
remains valid in the lifetime_rec parameter.
Send the actual TGS remaining lifetime to the kernel. It can still be
overwritten by the gssd -t command line option, or set to the kernel default
if the gss_inquire_cred call fails (which sets the lifetime_rec to zero).
Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
---
utils/gssd/gssd_proc.c | 19 ++++++++++++++++---
1 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index aa39435..c8d8142 100644
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -640,19 +640,22 @@ parse_enctypes(char *enctypes)
static int
do_downcall(int k5_fd, uid_t uid, struct authgss_private_data *pd,
- gss_buffer_desc *context_token)
+ gss_buffer_desc *context_token, OM_uint32 lifetime_rec)
{
char *buf = NULL, *p = NULL, *end = NULL;
unsigned int timeout = context_timeout;
unsigned int buf_size = 0;
- printerr(1, "doing downcall\n");
+ printerr(1, "doing downcall lifetime_rec %u\n", lifetime_rec);
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;
p = buf = malloc(buf_size);
end = buf + buf_size;
+ /* context_timeout set by -t option overrides context lifetime */
+ if (timeout == 0)
+ timeout = lifetime_rec;
if (WRITE_BYTES(&p, end, uid)) goto out_err;
if (WRITE_BYTES(&p, end, timeout)) goto out_err;
if (WRITE_BYTES(&p, end, pd->pd_seq_win)) goto out_err;
@@ -952,6 +955,7 @@ process_krb5_upcall(struct clnt_info *clp, uid_t uid, int fd, char *tgtname,
char **dirname, *dir, *userdir;
int create_resp = -1;
int err, downcall_err = -EACCES;
+ OM_uint32 maj_stat, min_stat, lifetime_rec;
printerr(1, "handling krb5 upcall (%s)\n", clp->dirname);
@@ -1077,6 +1081,15 @@ 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 */
+ maj_stat = gss_inquire_context(&min_stat, pd.pd_ctx, NULL, NULL,
+ &lifetime_rec, NULL, NULL, NULL, NULL);
+
+ if (maj_stat)
+ printerr(1, "WARNING: Failed to inquire context for lifetme "
+ "maj_stat %u\n", maj_stat);
+
if (serialize_context_for_kernel(pd.pd_ctx, &token, &krb5oid, NULL)) {
printerr(0, "WARNING: Failed to serialize krb5 context for "
"user with uid %d for server %s\n",
@@ -1084,7 +1097,7 @@ process_krb5_upcall(struct clnt_info *clp, uid_t uid, int fd, char *tgtname,
goto out_return_error;
}
- do_downcall(fd, uid, &pd, &token);
+ do_downcall(fd, uid, &pd, &token, lifetime_rec);
out:
if (token.value)
--
1.7.7.6
--
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