* [PATCH 1/3] gssd: use pthreads to handle upcalls
2016-02-22 15:28 [RFC PATCH 0/3] adding pthread support to gssd Olga Kornievskaia
@ 2016-02-22 15:28 ` Olga Kornievskaia
2016-02-22 15:28 ` [PATCH 2/3] gssd: using syscalls directly to change thread's identity Olga Kornievskaia
2016-02-22 15:28 ` [PATCH 3/3] gssd: always call gss_krb5_ccache_name Olga Kornievskaia
2 siblings, 0 replies; 4+ messages in thread
From: Olga Kornievskaia @ 2016-02-22 15:28 UTC (permalink / raw)
To: steved; +Cc: linux-nfs
Currently, to persevere global data over multiple mounts,
the root process does not fork when handling an upcall.
Instead on not-forking create a pthread to handle the
upcall since global data can be shared among threads.
Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
---
configure.ac | 3 +++
utils/gssd/Makefile.am | 3 ++-
utils/gssd/gssd.c | 34 +++++++++++++++++++++++++++++++---
utils/gssd/gssd.h | 2 ++
utils/gssd/gssd_proc.c | 30 ------------------------------
utils/gssd/krb5_util.c | 3 +++
6 files changed, 41 insertions(+), 34 deletions(-)
diff --git a/configure.ac b/configure.ac
index 25d2ba4..e0ecd61 100644
--- a/configure.ac
+++ b/configure.ac
@@ -385,6 +385,9 @@ if test "$enable_gss" = yes; then
dnl Invoked after AC_KERBEROS_V5; AC_LIBRPCSECGSS needs to have KRBLIBS set
AC_LIBRPCSECGSS
+ dnl Check for pthreads
+ AC_LIBPTHREAD
+
dnl librpcsecgss already has a dependency on libgssapi,
dnl but we need to make sure we get the right version
if test "$enable_gss" = yes; then
diff --git a/utils/gssd/Makefile.am b/utils/gssd/Makefile.am
index cb040b3..3f5f59a 100644
--- a/utils/gssd/Makefile.am
+++ b/utils/gssd/Makefile.am
@@ -49,7 +49,8 @@ gssd_LDADD = \
$(RPCSECGSS_LIBS) \
$(KRBLIBS) \
$(GSSAPI_LIBS) \
- $(LIBTIRPC)
+ $(LIBTIRPC) \
+ $(LIBPTHREAD)
gssd_LDFLAGS = \
$(KRBLDFLAGS)
diff --git a/utils/gssd/gssd.c b/utils/gssd/gssd.c
index e7cb07f..a480417 100644
--- a/utils/gssd/gssd.c
+++ b/utils/gssd/gssd.c
@@ -361,20 +361,48 @@ gssd_destroy_client(struct clnt_info *clp)
static void gssd_scan(void);
+/* For each upcall create a thread, detach from the main process so that
+ * resources are released back into the system without the need for a join.
+ * pthread_yield() is needed to allow the child thread to run right away
+ * and consume the upcall from the file descriptor. otherwise, if the main
+ * thread goes back into libevent code it will trigger another callback as
+ * the file descriptor is still "ready" and not consumed"
+ */
static void
gssd_clnt_gssd_cb(int UNUSED(fd), short UNUSED(which), void *data)
{
struct clnt_info *clp = data;
-
- handle_gssd_upcall(clp);
+ pthread_t th;
+ int ret;
+
+ ret = pthread_create(&th, NULL, (void *)handle_gssd_upcall,
+ (void *)clp);
+ if (ret != 0) {
+ printerr(0, "ERROR: pthread_create failed: ret %d: %s\n",
+ ret, strerror(errno));
+ return;
+ }
+ pthread_detach(th);
+ pthread_yield();
}
static void
gssd_clnt_krb5_cb(int UNUSED(fd), short UNUSED(which), void *data)
{
struct clnt_info *clp = data;
+ pthread_t th;
+ int ret;
+
+ ret = pthread_create(&th, NULL, (void *)handle_krb5_upcall,
+ (void *)clp);
+ if (ret != 0) {
+ printerr(0, "ERROR: pthread_create failed: ret %d: %s\n",
+ ret, strerror(errno));
+ return;
+ }
- handle_krb5_upcall(clp);
+ pthread_detach(th);
+ pthread_yield();
}
static struct clnt_info *
diff --git a/utils/gssd/gssd.h b/utils/gssd/gssd.h
index c6937c5..8677329 100644
--- a/utils/gssd/gssd.h
+++ b/utils/gssd/gssd.h
@@ -36,6 +36,7 @@
#include <gssapi/gssapi.h>
#include <event.h>
#include <stdbool.h>
+#include <pthread.h>
#ifndef GSSD_PIPEFS_DIR
#define GSSD_PIPEFS_DIR "/var/lib/nfs/rpc_pipefs"
@@ -61,6 +62,7 @@ extern int root_uses_machine_creds;
extern unsigned int context_timeout;
extern unsigned int rpc_timeout;
extern char *preferred_realm;
+extern pthread_mutex_t ple_lock;
struct clnt_info {
TAILQ_ENTRY(clnt_info) list;
diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index 1ef68d8..616082e 100644
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -629,36 +629,6 @@ process_krb5_upcall(struct clnt_info *clp, uid_t uid, int fd, char *tgtname,
if (uid != 0 || (uid == 0 && root_uses_machine_creds == 0 &&
service == NULL)) {
- /* already running as uid 0 */
- if (uid == 0)
- goto no_fork;
-
- pid = fork();
- switch(pid) {
- case 0:
- /* Child: fall through to rest of function */
- childpid = getpid();
- unsetenv("KRB5CCNAME");
- printerr(2, "CHILD forked pid %d \n", childpid);
- break;
- case -1:
- /* fork() failed! */
- printerr(0, "WARNING: unable to fork() to handle"
- "upcall: %s\n", strerror(errno));
- return;
- default:
- /* Parent: just wait on child to exit and return */
- do {
- pid = wait(&err);
- } while(pid == -1 && errno != -ECHILD);
-
- if (WIFSIGNALED(err))
- printerr(0, "WARNING: forked child was killed"
- "with signal %d\n", WTERMSIG(err));
- return;
- }
-no_fork:
-
auth = krb5_not_machine_creds(clp, uid, tgtname, &downcall_err,
&err, &rpc_clnt);
if (err)
diff --git a/utils/gssd/krb5_util.c b/utils/gssd/krb5_util.c
index 8ef8184..3328696 100644
--- a/utils/gssd/krb5_util.c
+++ b/utils/gssd/krb5_util.c
@@ -128,6 +128,7 @@
/* Global list of principals/cache file names for machine credentials */
struct gssd_k5_kt_princ *gssd_k5_kt_princ_list = NULL;
+pthread_mutex_t ple_lock = PTHREAD_MUTEX_INITIALIZER;
#ifdef HAVE_SET_ALLOWABLE_ENCTYPES
int limit_to_legacy_enctypes = 0;
@@ -586,10 +587,12 @@ get_ple_by_princ(krb5_context context, krb5_principal princ)
/* Need to serialize list if we ever become multi-threaded! */
+ pthread_mutex_lock(&ple_lock);
ple = find_ple_by_princ(context, princ);
if (ple == NULL) {
ple = new_ple(context, princ);
}
+ pthread_mutex_unlock(&ple_lock);
return ple;
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 2/3] gssd: using syscalls directly to change thread's identity
2016-02-22 15:28 [RFC PATCH 0/3] adding pthread support to gssd Olga Kornievskaia
2016-02-22 15:28 ` [PATCH 1/3] gssd: use pthreads to handle upcalls Olga Kornievskaia
@ 2016-02-22 15:28 ` Olga Kornievskaia
2016-02-22 15:28 ` [PATCH 3/3] gssd: always call gss_krb5_ccache_name Olga Kornievskaia
2 siblings, 0 replies; 4+ messages in thread
From: Olga Kornievskaia @ 2016-02-22 15:28 UTC (permalink / raw)
To: steved; +Cc: linux-nfs
For the threaded version we have to set uid,gid per thread instead
of per process. glibc setresuid() when called from a thread, it'll
send a signal to all other threads to synchronize the uid in all
other threads. To bypass this, we have to call syscall() directly.
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
---
utils/gssd/gssd_proc.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index 616082e..fee72c6 100644
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -69,6 +69,7 @@
#include <netdb.h>
#include <sys/types.h>
#include <sys/wait.h>
+#include <syscall.h>
#include "gssd.h"
#include "err_util.h"
@@ -457,7 +458,12 @@ change_identity(uid_t uid)
* Switch the GIDs. Note that we leave the saved-set-gid alone in an
* attempt to prevent attacks via ptrace()
*/
- if (setresgid(pw->pw_gid, pw->pw_gid, -1) != 0) {
+ /* For the threaded version we have to set uid,gid per thread instead
+ * of per process. glibc setresuid() when called from a thread, it'll
+ * send a signal to all other threads to synchronize the uid in all
+ * other threads. To bypass this, we have to call syscall() directly.
+ */
+ if (syscall(SYS_setresgid, pw->pw_gid) != 0) {
printerr(0, "WARNING: failed to set gid to %u!\n", pw->pw_gid);
return errno;
}
@@ -466,7 +472,7 @@ change_identity(uid_t uid)
* Switch UIDs, but leave saved-set-uid alone to prevent ptrace() by
* other processes running with this uid.
*/
- if (setresuid(uid, uid, -1) != 0) {
+ if (syscall(SYS_setresuid, uid) != 0) {
printerr(0, "WARNING: Failed to setuid for user with uid %u\n",
uid);
return errno;
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 3/3] gssd: always call gss_krb5_ccache_name
2016-02-22 15:28 [RFC PATCH 0/3] adding pthread support to gssd Olga Kornievskaia
2016-02-22 15:28 ` [PATCH 1/3] gssd: use pthreads to handle upcalls Olga Kornievskaia
2016-02-22 15:28 ` [PATCH 2/3] gssd: using syscalls directly to change thread's identity Olga Kornievskaia
@ 2016-02-22 15:28 ` Olga Kornievskaia
2 siblings, 0 replies; 4+ messages in thread
From: Olga Kornievskaia @ 2016-02-22 15:28 UTC (permalink / raw)
To: steved; +Cc: linux-nfs
Previously the location of the credential cache was passed in either
using environment variable KRB5CCNAME or gss_krb5_ccache_name() if
supported. For threaded-gssd, we can't use an environment variable
as it's shared among all thread. Thus always use the api call.
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
---
utils/gssd/gssd_proc.c | 12 +++++++++--
utils/gssd/krb5_util.c | 56 +++++++++-----------------------------------------
utils/gssd/krb5_util.h | 1 -
3 files changed, 20 insertions(+), 49 deletions(-)
diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index fee72c6..bff29cf 100644
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -554,7 +554,15 @@ krb5_use_machine_creds(struct clnt_info *clp, uid_t uid, char *tgtname,
goto out;
}
for (ccname = credlist; ccname && *ccname; ccname++) {
- gssd_setup_krb5_machine_gss_ccache(*ccname);
+ u_int min_stat;
+
+ if (gss_krb5_ccache_name(&min_stat, *ccname, NULL) !=
+ GSS_S_COMPLETE) {
+ printerr(1, "WARNING: gss_krb5_ccache_name "
+ "with name '%s' failed (%s)\n",
+ *ccname, error_message(min_stat));
+ continue;
+ }
if ((create_auth_rpc_client(clp, tgtname, rpc_clnt,
&auth, uid,
AUTHTYPE_KRB5,
@@ -575,7 +583,7 @@ krb5_use_machine_creds(struct clnt_info *clp, uid_t uid, char *tgtname,
"recreate cache for server %s\n",
clp->servername);
} else {
- printerr(1, "WARNING: Failed to create machine"
+ printerr(0, "ERROR: Failed to create machine"
"krb5 context with any credentials"
"cache for server %s\n",
clp->servername);
diff --git a/utils/gssd/krb5_util.c b/utils/gssd/krb5_util.c
index 3328696..7b74ab3 100644
--- a/utils/gssd/krb5_util.c
+++ b/utils/gssd/krb5_util.c
@@ -468,37 +468,6 @@ gssd_get_single_krb5_cred(krb5_context context,
}
/*
- * Depending on the version of Kerberos, we either need to use
- * a private function, or simply set the environment variable.
- */
-static void
-gssd_set_krb5_ccache_name(char *ccname)
-{
-#ifdef USE_GSS_KRB5_CCACHE_NAME
- u_int maj_stat, min_stat;
-
- printerr(3, "using gss_krb5_ccache_name to select krb5 ccache %s\n",
- ccname);
- maj_stat = gss_krb5_ccache_name(&min_stat, ccname, NULL);
- if (maj_stat != GSS_S_COMPLETE) {
- printerr(0, "WARNING: gss_krb5_ccache_name with "
- "name '%s' failed (%s)\n",
- ccname, error_message(min_stat));
- }
-#else
- /*
- * Set the KRB5CCNAME environment variable to tell the krb5 code
- * which credentials cache to use. (Instead of using the private
- * function above for which there is no generic gssapi
- * equivalent.)
- */
- printerr(3, "using environment variable to select krb5 ccache %s\n",
- ccname);
- setenv("KRB5CCNAME", ccname, 1);
-#endif
-}
-
-/*
* Given a principal, find a matching ple structure
*/
static struct gssd_k5_kt_princ *
@@ -1094,6 +1063,7 @@ gssd_setup_krb5_user_gss_ccache(uid_t uid, char *servername, char *dirpattern)
const char *cctype;
struct dirent *d;
int err, i, j;
+ u_int maj_stat, min_stat;
printerr(3, "looking for client creds with uid %u for "
"server %s in %s\n", uid, servername, dirpattern);
@@ -1129,22 +1099,16 @@ gssd_setup_krb5_user_gss_ccache(uid_t uid, char *servername, char *dirpattern)
printerr(2, "using %s as credentials cache for client with "
"uid %u for server %s\n", buf, uid, servername);
- gssd_set_krb5_ccache_name(buf);
- return 0;
-}
-/*
- * Let the gss code know where to find the machine credentials ccache.
- *
- * Returns:
- * void
- */
-void
-gssd_setup_krb5_machine_gss_ccache(char *ccname)
-{
- printerr(2, "using %s as credentials cache for machine creds\n",
- ccname);
- gssd_set_krb5_ccache_name(ccname);
+ printerr(3, "using gss_krb5_ccache_name to select krb5 ccache %s\n",
+ buf);
+ maj_stat = gss_krb5_ccache_name(&min_stat, buf, NULL);
+ if (maj_stat != GSS_S_COMPLETE) {
+ printerr(0, "ERROR: unable to get user cred cache '%s' "
+ "failed (%s)\n", buf, error_message(min_stat));
+ return maj_stat;
+ }
+ return 0;
}
/*
diff --git a/utils/gssd/krb5_util.h b/utils/gssd/krb5_util.h
index a319588..d3b0777 100644
--- a/utils/gssd/krb5_util.h
+++ b/utils/gssd/krb5_util.h
@@ -27,7 +27,6 @@ int gssd_setup_krb5_user_gss_ccache(uid_t uid, char *servername,
char *dirname);
int gssd_get_krb5_machine_cred_list(char ***list);
void gssd_free_krb5_machine_cred_list(char **list);
-void gssd_setup_krb5_machine_gss_ccache(char *servername);
void gssd_destroy_krb5_machine_creds(void);
int gssd_refresh_krb5_machine_credential(char *hostname,
struct gssd_k5_kt_princ *ple,
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread