sssd/0503-sss_client-Defer-thread-cancellation-until-completio.patch

From d2f93542650c2f9613043acfa8e2f368972a70cd Mon Sep 17 00:00:00 2001
From: Howard Guo <hguo@suse.com>
Date: Tue, 11 Oct 2016 10:35:13 +0200
Subject: [PATCH] sss_client: Defer thread cancellation until completion of
 nss/pam operations

The client code is not cancellation-safe, an application which
has cancelled an NSS operation will experience subtle bugs,
hence thread cancellation is deferred until completion of client
operations.

Resolves:
https://fedorahosted.org/sssd/ticket/3156

Reviewed-by: Sumit Bose <sbose@redhat.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
---
 Makefile.am             |  4 ---
 configure.ac            |  8 -----
 src/sss_client/common.c | 80 +++++--------------------------------------------
 3 files changed, 7 insertions(+), 85 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index e037930ff..9f1da4d1e 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -792,10 +792,6 @@ endif
 
 CLIENT_LIBS = $(LTLIBINTL)
 
-if HAVE_PTHREAD
-CLIENT_LIBS += -lpthread
-endif
-
 if WITH_JOURNALD
 SYSLOG_LIBS = $(JOURNALD_LIBS)
 endif
diff --git a/configure.ac b/configure.ac
index d3ef1e162..230524bf3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -62,14 +62,6 @@ AC_COMPILE_IFELSE(
 
 AM_CONDITIONAL([HAVE_PTHREAD], [test x"$HAVE_PTHREAD" != "x"])
 
-SAVE_LIBS=$LIBS
-LIBS="$LIBS -lpthread"
-AC_CHECK_FUNCS([ pthread_mutexattr_setrobust \
-                 pthread_mutex_consistent \
-                 pthread_mutexattr_setrobust_np \
-                 pthread_mutex_consistent_np ])
-LIBS=$SAVE_LIBS
-
 # Check library for the timer_create function
 SAVE_LIBS=$LIBS
 LIBS=
diff --git a/src/sss_client/common.c b/src/sss_client/common.c
index 20106b1b6..b7a5ed760 100644
--- a/src/sss_client/common.c
+++ b/src/sss_client/common.c
@@ -1070,86 +1070,28 @@ typedef void (*sss_mutex_init)(void);
 struct sss_mutex {
     pthread_mutex_t mtx;
 
-    pthread_once_t once;
-    sss_mutex_init init;
+    int old_cancel_state;
 };
 
-static void sss_nss_mt_init(void);
-static void sss_pam_mt_init(void);
-static void sss_nss_mc_mt_init(void);
+static struct sss_mutex sss_nss_mtx = { .mtx  = PTHREAD_MUTEX_INITIALIZER };
 
-static struct sss_mutex sss_nss_mtx = { .mtx  = PTHREAD_MUTEX_INITIALIZER,
-                                        .once = PTHREAD_ONCE_INIT,
-                                        .init = sss_nss_mt_init };
+static struct sss_mutex sss_pam_mtx = { .mtx  = PTHREAD_MUTEX_INITIALIZER };
 
-static struct sss_mutex sss_pam_mtx = { .mtx  = PTHREAD_MUTEX_INITIALIZER,
-                                        .once = PTHREAD_ONCE_INIT,
-                                        .init = sss_pam_mt_init };
-
-static struct sss_mutex sss_nss_mc_mtx = { .mtx  = PTHREAD_MUTEX_INITIALIZER,
-                                           .once = PTHREAD_ONCE_INIT,
-                                           .init = sss_nss_mc_mt_init };
-
-/* Wrappers for robust mutex support */
-static int sss_mutexattr_setrobust (pthread_mutexattr_t *attr)
-{
-#ifdef HAVE_PTHREAD_MUTEXATTR_SETROBUST
-    return pthread_mutexattr_setrobust(attr, PTHREAD_MUTEX_ROBUST);
-#elif defined(HAVE_PTHREAD_MUTEXATTR_SETROBUST_NP)
-    return pthread_mutexattr_setrobust_np(attr, PTHREAD_MUTEX_ROBUST_NP);
-#else
-#warning Robust mutexes are not supported on this platform.
-    return 0;
-#endif
-}
-
-static int sss_mutex_consistent(pthread_mutex_t *mtx)
-{
-#ifdef HAVE_PTHREAD_MUTEX_CONSISTENT
-    return pthread_mutex_consistent(mtx);
-#elif defined(HAVE_PTHREAD_MUTEX_CONSISTENT_NP)
-    return pthread_mutex_consistent_np(mtx);
-#else
-#warning Robust mutexes are not supported on this platform.
-    return 0;
-#endif
-}
-
-/* Generic mutex init, lock, unlock functions */
-static void sss_mt_init(struct sss_mutex *m)
-{
-    pthread_mutexattr_t attr;
-
-    if (pthread_mutexattr_init(&attr) != 0) {
-        return;
-    }
-    if (sss_mutexattr_setrobust(&attr) != 0) {
-        return;
-    }
-
-    pthread_mutex_init(&m->mtx, &attr);
-    pthread_mutexattr_destroy(&attr);
-}
+static struct sss_mutex sss_nss_mc_mtx = { .mtx  = PTHREAD_MUTEX_INITIALIZER };
 
 static void sss_mt_lock(struct sss_mutex *m)
 {
-    pthread_once(&m->once, m->init);
-    if (pthread_mutex_lock(&m->mtx) == EOWNERDEAD) {
-        sss_cli_close_socket();
-        sss_mutex_consistent(&m->mtx);
-    }
+    pthread_mutex_lock(&m->mtx);
+    pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &m->old_cancel_state);
 }
 
 static void sss_mt_unlock(struct sss_mutex *m)
 {
+    pthread_setcancelstate(m->old_cancel_state, NULL);
     pthread_mutex_unlock(&m->mtx);
 }
 
 /* NSS mutex wrappers */
-static void sss_nss_mt_init(void)
-{
-    sss_mt_init(&sss_nss_mtx);
-}
 void sss_nss_lock(void)
 {
     sss_mt_lock(&sss_nss_mtx);
@@ -1160,10 +1102,6 @@ void sss_nss_unlock(void)
 }
 
 /* NSS mutex wrappers */
-static void sss_pam_mt_init(void)
-{
-    sss_mt_init(&sss_pam_mtx);
-}
 void sss_pam_lock(void)
 {
     sss_mt_lock(&sss_pam_mtx);
@@ -1174,10 +1112,6 @@ void sss_pam_unlock(void)
 }
 
 /* NSS mutex wrappers */
-static void sss_nss_mc_mt_init(void)
-{
-    sss_mt_init(&sss_nss_mc_mtx);
-}
 void sss_nss_mc_lock(void)
 {
     sss_mt_lock(&sss_nss_mc_mtx);
-- 
2.11.0