From c6847f012b326a7e27dbe79d8df0faafdeb2dbef Mon Sep 17 00:00:00 2001
From: Scott Mayhew <smayhew@redhat.com>
Date: Thu, 2 Sep 2021 12:44:27 -0400
Subject: [PATCH] Add an option for minimum lifetime
It's possible for gssproxy to return a cached credential with a very
small remaining lifetime. This can be problematic for NFS clients since
it requires a round trip to the NFS server to establish a GSS context.
Add a min_lifetime option that represents the lowest value that the
lifetime of the cached credential can be. Any lower than that, and
gp_check_cred() returns GSS_S_CREDENTIALS_EXPIRED, so that
gp_add_krb5_creds() is forced to try to obtain a new credential.
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
[antorres@redhat.com: adjusted lines number for man diff]
---
examples/99-nfs-client.conf.in | 1 +
man/gssproxy.conf.5.xml | 15 +++++++++++++++
src/gp_config.c | 12 ++++++++++++
src/gp_creds.c | 12 ++++++++++--
src/gp_proxy.h | 1 +
5 files changed, 39 insertions(+), 2 deletions(-)
diff --git a/examples/99-nfs-client.conf.in b/examples/99-nfs-client.conf.in
index c0985d9..9dd1891 100644
--- a/examples/99-nfs-client.conf.in
+++ b/examples/99-nfs-client.conf.in
@@ -7,3 +7,4 @@
allow_any_uid = yes
trusted = yes
euid = 0
+ min_lifetime = 60
diff --git a/man/gssproxy.conf.5.xml b/man/gssproxy.conf.5.xml
index de846b4..af6ca18 100644
--- a/man/gssproxy.conf.5.xml
+++ b/man/gssproxy.conf.5.xml
@@ -348,6 +348,21 @@
</listitem>
</varlistentry>
+ <varlistentry>
+ <term>min_lifetime (integer)</term>
+ <listitem>
+ <para>Minimum lifetime of a cached credential, in seconds.</para>
+ <para>If non-zero, when gssproxy is deciding whether to use
+ a cached credential, it will compare the lifetime of the
+ cached credential to this value. If the lifetime of the
+ cached credential is lower, gssproxy will treat the cached
+ credential as expired and will attempt to obtain a new
+ credential.
+ </para>
+ <para>Default: min_lifetime = 15</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term>program (string)</term>
<listitem>
diff --git a/src/gp_config.c b/src/gp_config.c
index 4cda579..a0afa73 100644
--- a/src/gp_config.c
+++ b/src/gp_config.c
@@ -32,6 +32,7 @@ struct gp_flag_def flag_names[] = {
#define DEFAULT_FILTERED_FLAGS GSS_C_DELEG_FLAG
#define DEFAULT_ENFORCED_FLAGS 0
+#define DEFAULT_MIN_LIFETIME 15
static void free_str_array(const char ***a, int *count)
{
@@ -538,6 +539,17 @@ static int load_services(struct gp_config *cfg, struct gp_ini_context *ctx)
goto done;
}
}
+
+ cfg->svcs[n]->min_lifetime = DEFAULT_MIN_LIFETIME;
+ ret = gp_config_get_int(ctx, secname, "min_lifetime", &valnum);
+ if (ret == 0) {
+ if (valnum >= 0) {
+ cfg->svcs[n]->min_lifetime = valnum;
+ } else {
+ GPDEBUG("Invalid value '%d' for min_lifetime in [%s], ignoring.\n",
+ valnum, secname);
+ }
+ }
}
safefree(secname);
}
diff --git a/src/gp_creds.c b/src/gp_creds.c
index 92a6f13..843d1a3 100644
--- a/src/gp_creds.c
+++ b/src/gp_creds.c
@@ -492,6 +492,7 @@ done:
}
static uint32_t gp_check_cred(uint32_t *min,
+ struct gp_service *svc,
gss_cred_id_t in_cred,
gssx_name *desired_name,
gss_cred_usage_t cred_usage)
@@ -563,7 +564,14 @@ static uint32_t gp_check_cred(uint32_t *min,
if (lifetime == 0) {
ret_maj = GSS_S_CREDENTIALS_EXPIRED;
} else {
- ret_maj = GSS_S_COMPLETE;
+ if (svc->min_lifetime && lifetime < svc->min_lifetime) {
+ GPDEBUG("%s: lifetime (%u) less than min_lifetime (%u) "
+ "for service \"%s\" - returning\n",
+ __func__, lifetime, svc->min_lifetime, svc->name);
+ ret_maj = GSS_S_CREDENTIALS_EXPIRED;
+ } else {
+ ret_maj = GSS_S_COMPLETE;
+ }
}
done:
@@ -622,7 +630,7 @@ uint32_t gp_add_krb5_creds(uint32_t *min,
* function completely */
/* just check if it is a valid krb5 cred */
- ret_maj = gp_check_cred(&ret_min, in_cred, desired_name, cred_usage);
+ ret_maj = gp_check_cred(&ret_min, gpcall->service, in_cred, desired_name, cred_usage);
if (ret_maj == GSS_S_COMPLETE) {
return GSS_S_COMPLETE;
} else if (ret_maj == GSS_S_CREDENTIALS_EXPIRED ||
diff --git a/src/gp_proxy.h b/src/gp_proxy.h
index 3f58a43..f56d640 100644
--- a/src/gp_proxy.h
+++ b/src/gp_proxy.h
@@ -45,6 +45,7 @@ struct gp_service {
gss_cred_usage_t cred_usage;
uint32_t filter_flags;
uint32_t enforce_flags;
+ uint32_t min_lifetime;
char *program;
uint32_t mechs;
--
2.31.1