Revert the crypto "global lock" implementation
authorBenjamin Kaduk <bkaduk@akamai.com>
Tue, 16 Jan 2018 15:49:54 +0000 (09:49 -0600)
committerBen Kaduk <kaduk@mit.edu>
Wed, 31 Jan 2018 18:25:28 +0000 (12:25 -0600)
Conceptually, this is a squashed version of:

    Revert "Address feedback"

    This reverts commit 75551e07bd2339dfea06ef1d31d69929e13a4495.

and

    Revert "Add CRYPTO_thread_glock_new"

    This reverts commit ed6b2c7938ec6f07b15745d4183afc276e74c6dd.

But there were some intervening commits that made neither revert apply
cleanly, so instead do it all as one shot.

The crypto global locks were an attempt to cope with the awkward
POSIX semantics for pthread_atfork(); its documentation (the "RATIONALE"
section) indicates that the expected usage is to have the prefork handler
lock all "global" locks, and the parent and child handlers release those
locks, to ensure that forking happens with a consistent (lock) state.
However, the set of functions available in the child process is limited
to async-signal-safe functions, and pthread_mutex_unlock() is not on
the list of async-signal-safe functions!  The only synchronization
primitives that are async-signal-safe are the semaphore primitives,
which are not really appropriate for general-purpose usage.

However, the state consistency problem that the global locks were
attempting to solve is not actually a serious problem, particularly for
OpenSSL.  That is, we can consider four cases of forking application
that might use OpenSSL:

(1) Single-threaded, does not call into OpenSSL in the child (e.g.,
the child calls exec() immediately)

For this class of process, no locking is needed at all, since there is
only ever a single thread of execution and the only reentrancy is due to
signal handlers (which are themselves limited to async-signal-safe
operation and should not be doing much work at all).

(2) Single-threaded, calls into OpenSSL after fork()

The application must ensure that it does not fork() with an unexpected
lock held (that is, one that would get unlocked in the parent but
accidentally remain locked in the child and cause deadlock).  Since
OpenSSL does not expose any of its internal locks to the application
and the application is single-threaded, the OpenSSL internal locks
will be unlocked for the fork(), and the state will be consistent.
(OpenSSL will need to reseed its PRNG in the child, but that is
an orthogonal issue.)  If the application makes use of locks from
libcrypto, proper handling for those locks is the responsibility of
the application, as for any other locking primitive that is available
for application programming.

(3) Multi-threaded, does not call into OpenSSL after fork()

As for (1), the OpenSSL state is only relevant in the parent, so
no particular fork()-related handling is needed.  The internal locks
are relevant, but there is no interaction with the child to consider.

(4) Multi-threaded, calls into OpenSSL after fork()

This is the case where the pthread_atfork() hooks to ensure that all
global locks are in a known state across fork() would come into play,
per the above discussion.  However, these "calls into OpenSSL after
fork()" are still subject to the restriction to async-signal-safe
functions.  Since OpenSSL uses all sorts of locking and libc functions
that are not on the list of safe functions (e.g., malloc()), this
case is not currently usable and is unlikely to ever be usable,
independently of the locking situation.  So, there is no need to
go through contortions to attempt to support this case in the one small
area of locking interaction with fork().

In light of the above analysis (thanks @davidben and @achernya), go
back to the simpler implementation that does not need to distinguish
"library-global" locks or to have complicated atfork handling for locks.

Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/5089)

14 files changed:
crypto/bio/b_addr.c
crypto/bio/bio_meth.c
crypto/engine/eng_lib.c
crypto/err/err.c
crypto/ex_data.c
crypto/init.c
crypto/mem_dbg.c
crypto/mem_sec.c
crypto/objects/o_names.c
crypto/rand/drbg_lib.c
crypto/rand/rand_lib.c
crypto/store/store_register.c
include/openssl/crypto.h
util/libcrypto.num

index 6fb135a..ab8e7ff 100644 (file)
@@ -603,7 +603,7 @@ static int addrinfo_wrap(int family, int socktype,
 DEFINE_RUN_ONCE_STATIC(do_bio_lookup_init)
 {
     OPENSSL_init_crypto(0, NULL);
-    bio_lookup_lock = CRYPTO_THREAD_glock_new("bio_lookup");
+    bio_lookup_lock = CRYPTO_THREAD_lock_new();
     return bio_lookup_lock != NULL;
 }
 
index 955be84..1c5d196 100644 (file)
@@ -15,7 +15,7 @@ static CRYPTO_ONCE bio_type_init = CRYPTO_ONCE_STATIC_INIT;
 
 DEFINE_RUN_ONCE_STATIC(do_bio_type_init)
 {
-    bio_type_lock = CRYPTO_THREAD_glock_new("bio_type");
+    bio_type_lock = CRYPTO_THREAD_lock_new();
     return bio_type_lock != NULL;
 }
 
index 8f65584..db7717f 100644 (file)
@@ -21,7 +21,7 @@ CRYPTO_ONCE engine_lock_init = CRYPTO_ONCE_STATIC_INIT;
 DEFINE_RUN_ONCE(do_engine_lock_init)
 {
     OPENSSL_init_crypto(0, NULL);
-    global_engine_lock = CRYPTO_THREAD_glock_new("global_engine");
+    global_engine_lock = CRYPTO_THREAD_lock_new();
     return global_engine_lock != NULL;
 }
 
index c0bdbb8..a83da9b 100644 (file)
@@ -266,7 +266,7 @@ static void ERR_STATE_free(ERR_STATE *s)
 DEFINE_RUN_ONCE_STATIC(do_err_strings_init)
 {
     OPENSSL_init_crypto(0, NULL);
-    err_string_lock = CRYPTO_THREAD_glock_new("err_string");
+    err_string_lock = CRYPTO_THREAD_lock_new();
     int_error_hash = lh_ERR_STRING_DATA_new(err_string_data_hash,
                                             err_string_data_cmp);
     return err_string_lock != NULL && int_error_hash != NULL;
index 78162b5..538fdb1 100644 (file)
@@ -38,7 +38,7 @@ static CRYPTO_ONCE ex_data_init = CRYPTO_ONCE_STATIC_INIT;
 DEFINE_RUN_ONCE_STATIC(do_ex_data_init)
 {
     OPENSSL_init_crypto(0, NULL);
-    ex_data_lock = CRYPTO_THREAD_glock_new("ex_data");
+    ex_data_lock = CRYPTO_THREAD_lock_new();
     return ex_data_lock != NULL;
 }
 
index 909775a..71accaa 100644 (file)
 #include "internal/dso.h"
 #include "internal/store.h"
 
-
-typedef struct global_lock_st {
-    CRYPTO_RWLOCK *lock;
-    const char *name;
-    struct global_lock_st *next;
-} GLOBAL_LOCK;
-
-static GLOBAL_LOCK *global_locks;
-
 static int stopped = 0;
 
 static void ossl_init_thread_stop(struct thread_local_inits_st *locals);
@@ -72,8 +63,6 @@ struct ossl_init_stop_st {
     OPENSSL_INIT_STOP *next;
 };
 
-static CRYPTO_RWLOCK *glock_lock = NULL;
-
 static OPENSSL_INIT_STOP *stop_handlers = NULL;
 static CRYPTO_RWLOCK *init_lock = NULL;
 
@@ -95,7 +84,6 @@ DEFINE_RUN_ONCE_STATIC(ossl_init_base)
 #ifndef OPENSSL_SYS_UEFI
     atexit(OPENSSL_cleanup);
 #endif
-    /* Do not change this to glock's! */
     if ((init_lock = CRYPTO_THREAD_lock_new()) == NULL)
         return 0;
     OPENSSL_cpuid_setup();
@@ -433,7 +421,6 @@ void OPENSSL_cleanup(void)
     stop_handlers = NULL;
 
     CRYPTO_THREAD_lock_free(init_lock);
-    init_lock = NULL;
 
     /*
      * We assume we are single-threaded for this function, i.e. no race
@@ -514,16 +501,6 @@ void OPENSSL_cleanup(void)
     obj_cleanup_int();
     err_cleanup();
 
-    /* Free list of global locks. */
-    while (global_locks != NULL) {
-        GLOBAL_LOCK *next = global_locks->next;
-
-        free(global_locks);
-        global_locks = next;
-    }
-    CRYPTO_THREAD_lock_free(glock_lock);
-    glock_lock = NULL;
-
     base_inited = 0;
 }
 
@@ -707,56 +684,7 @@ int OPENSSL_atexit(void (*handler)(void))
     return 1;
 }
 
-#ifndef OPENSSL_SYS_UNIX
-CRYPTO_RWLOCK *CRYPTO_THREAD_glock_new(const char *name)
-{
-    return CRYPTO_THREAD_lock_new();
-}
-
-#else
-DEFINE_RUN_ONCE_STATIC(glock_init)
-{
-    glock_lock = CRYPTO_THREAD_lock_new();
-    return glock_lock != NULL;
-}
-
-/*
- * Create a new global lock, return NULL on error.
- */
-CRYPTO_RWLOCK *CRYPTO_THREAD_glock_new(const char *name)
-{
-    static CRYPTO_ONCE glock_once = CRYPTO_ONCE_STATIC_INIT;
-    GLOBAL_LOCK *newlock;
-
-    if (glock_lock == NULL && !RUN_ONCE(&glock_once, glock_init))
-        return NULL;
-    if ((newlock = malloc(sizeof(*newlock))) == NULL)
-        return NULL;
-    if ((newlock->lock = CRYPTO_THREAD_lock_new()) == NULL) {
-        free(newlock);
-        return NULL;
-    }
-    newlock->name = name;
-    CRYPTO_THREAD_write_lock(glock_lock);
-    newlock->next = global_locks;
-    global_locks = newlock;
-    CRYPTO_THREAD_unlock(glock_lock);
-    return newlock->lock;
-}
-
-/*
- * Unlock all global locks.
- */
-static void unlock_all(void)
-{
-    GLOBAL_LOCK *lp;
-
-    CRYPTO_THREAD_write_lock(glock_lock);
-    for (lp = global_locks; lp != NULL; lp = lp->next)
-        CRYPTO_THREAD_unlock(lp->lock);
-    CRYPTO_THREAD_unlock(glock_lock);
-}
-
+#ifdef OPENSSL_SYS_UNIX
 /*
  * The following three functions are for OpenSSL developers.  This is
  * where we set/reset state across fork (called via pthread_atfork when
@@ -770,22 +698,14 @@ static void unlock_all(void)
 
 void OPENSSL_fork_prepare(void)
 {
-    GLOBAL_LOCK *lp;
-
-    CRYPTO_THREAD_write_lock(glock_lock);
-    for (lp = global_locks; lp != NULL; lp = lp->next)
-        CRYPTO_THREAD_write_lock(lp->lock);
-    CRYPTO_THREAD_unlock(glock_lock);
 }
 
 void OPENSSL_fork_parent(void)
 {
-    unlock_all();
 }
 
 void OPENSSL_fork_child(void)
 {
-    unlock_all();
     rand_fork();
 }
 #endif
index b394de8..e113882 100644 (file)
@@ -93,11 +93,10 @@ static CRYPTO_THREAD_ID disabling_threadid;
 
 DEFINE_RUN_ONCE_STATIC(do_memdbg_init)
 {
-    memdbg_lock = CRYPTO_THREAD_glock_new("malloc");
-    long_memdbg_lock = CRYPTO_THREAD_glock_new("long_malloc");
-    if (memdbg_lock == NULL
-            || long_memdbg_lock == NULL
-            || !CRYPTO_THREAD_init_local(&appinfokey, NULL)) {
+    memdbg_lock = CRYPTO_THREAD_lock_new();
+    long_memdbg_lock = CRYPTO_THREAD_lock_new();
+    if (memdbg_lock == NULL || long_memdbg_lock == NULL
+        || !CRYPTO_THREAD_init_local(&appinfokey, NULL)) {
         CRYPTO_THREAD_lock_free(memdbg_lock);
         memdbg_lock = NULL;
         CRYPTO_THREAD_lock_free(long_memdbg_lock);
index 8f4ae9c..4c01045 100644 (file)
@@ -68,7 +68,7 @@ int CRYPTO_secure_malloc_init(size_t size, int minsize)
     int ret = 0;
 
     if (!secure_mem_initialized) {
-        sec_malloc_lock = CRYPTO_THREAD_glock_new("sec_malloc");
+        sec_malloc_lock = CRYPTO_THREAD_lock_new();
         if (sec_malloc_lock == NULL)
             return 0;
         if ((ret = sh_init(size, minsize)) != 0) {
index d0e8e05..7367644 100644 (file)
@@ -69,7 +69,7 @@ DEFINE_RUN_ONCE_STATIC(o_names_init)
 {
     CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_DISABLE);
     names_lh = lh_OBJ_NAME_new(obj_name_hash, obj_name_cmp);
-    obj_lock = CRYPTO_THREAD_glock_new("obj");
+    obj_lock = CRYPTO_THREAD_lock_new();
     CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_ENABLE);
     return names_lh != NULL && obj_lock != NULL;
 }
index 5e6bdce..cb2f9e8 100644 (file)
@@ -98,7 +98,7 @@ static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG";
 
 static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT;
 
-static RAND_DRBG *drbg_setup(const char *name, RAND_DRBG *parent);
+static RAND_DRBG *drbg_setup(RAND_DRBG *parent);
 static void drbg_cleanup(RAND_DRBG *drbg);
 
 /*
@@ -666,24 +666,18 @@ void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
 /*
  * Allocates a new global DRBG on the secure heap (if enabled) and
  * initializes it with default settings.
- * A global lock for the DRBG is created with the given name.
  *
  * Returns a pointer to the new DRBG instance on success, NULL on failure.
  */
-static RAND_DRBG *drbg_setup(const char *name, RAND_DRBG *parent)
+static RAND_DRBG *drbg_setup(RAND_DRBG *parent)
 {
     RAND_DRBG *drbg;
 
-    if (name == NULL) {
-        RANDerr(RAND_F_DRBG_SETUP, ERR_R_INTERNAL_ERROR);
-        return NULL;
-    }
-
     drbg = OPENSSL_secure_zalloc(sizeof(RAND_DRBG));
     if (drbg == NULL)
         return NULL;
 
-    drbg->lock = CRYPTO_THREAD_glock_new(name);
+    drbg->lock = CRYPTO_THREAD_lock_new();
     if (drbg->lock == NULL) {
         RANDerr(RAND_F_DRBG_SETUP, RAND_R_FAILED_TO_CREATE_LOCK);
         goto err;
@@ -737,9 +731,9 @@ DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
     if (!OPENSSL_init_crypto(0, NULL))
         return 0;
 
-    drbg_master = drbg_setup("drbg_master", NULL);
-    drbg_public = drbg_setup("drbg_public", drbg_master);
-    drbg_private = drbg_setup("drbg_private", drbg_master);
+    drbg_master = drbg_setup(NULL);
+    drbg_public = drbg_setup(drbg_master);
+    drbg_private = drbg_setup(drbg_master);
 
     if (drbg_master == NULL || drbg_public == NULL || drbg_private == NULL)
         return 0;
index ab03356..20ac583 100644 (file)
@@ -282,10 +282,10 @@ DEFINE_RUN_ONCE_STATIC(do_rand_init)
     int ret = 1;
 
 #ifndef OPENSSL_NO_ENGINE
-    rand_engine_lock = CRYPTO_THREAD_glock_new("rand_engine");
+    rand_engine_lock = CRYPTO_THREAD_lock_new();
     ret &= rand_engine_lock != NULL;
 #endif
-    rand_meth_lock = CRYPTO_THREAD_glock_new("rand_meth");
+    rand_meth_lock = CRYPTO_THREAD_lock_new();
     ret &= rand_meth_lock != NULL;
 
     return ret;
index 987ca42..85c38b8 100644 (file)
@@ -20,7 +20,7 @@ static CRYPTO_ONCE registry_init = CRYPTO_ONCE_STATIC_INIT;
 
 DEFINE_RUN_ONCE_STATIC(do_registry_init)
 {
-    registry_lock = CRYPTO_THREAD_glock_new("registry");
+    registry_lock = CRYPTO_THREAD_lock_new();
     return registry_lock != NULL;
 }
 
index 5e9517d..478f9e2 100644 (file)
@@ -67,7 +67,6 @@ typedef struct {
 typedef void CRYPTO_RWLOCK;
 
 CRYPTO_RWLOCK *CRYPTO_THREAD_lock_new(void);
-CRYPTO_RWLOCK *CRYPTO_THREAD_glock_new(const char *name);
 int CRYPTO_THREAD_read_lock(CRYPTO_RWLOCK *lock);
 int CRYPTO_THREAD_write_lock(CRYPTO_RWLOCK *lock);
 int CRYPTO_THREAD_unlock(CRYPTO_RWLOCK *lock);
index 536a3d2..a2d03c6 100644 (file)
@@ -4388,7 +4388,6 @@ EVP_aria_256_ccm                        4332      1_1_1   EXIST::FUNCTION:ARIA
 EVP_aria_128_gcm                        4333   1_1_1   EXIST::FUNCTION:ARIA
 EVP_aria_128_ccm                        4334   1_1_1   EXIST::FUNCTION:ARIA
 EVP_aria_192_gcm                        4335   1_1_1   EXIST::FUNCTION:ARIA
-CRYPTO_THREAD_glock_new                 4336   1_1_1   EXIST::FUNCTION:
 UI_get_result_length                    4337   1_1_1   EXIST::FUNCTION:
 UI_set_result_ex                        4338   1_1_1   EXIST::FUNCTION:
 UI_get_result_string_length             4339   1_1_1   EXIST::FUNCTION: