Fix data race in RAND_DRBG_generate
[openssl.git] / crypto / rand / rand_lib.c
index 3589e75..440c19c 100644 (file)
 #include <openssl/engine.h>
 #include "internal/thread_once.h"
 #include "rand_lcl.h"
-#ifdef OPENSSL_SYS_UNIX
-# include <sys/types.h>
-# include <unistd.h>
-# include <sys/time.h>
-#endif
 #include "e_os.h"
 
-/* Macro to convert two thirty two bit values into a sixty four bit one */
-#define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
-
-/*
- * Check for the existence and support of POSIX timers.  The standard
- * says that the _POSIX_TIMERS macro will have a positive value if they
- * are available.
- *
- * However, we want an additional constraint: that the timer support does
- * not require an extra library dependency.  Early versions of glibc
- * require -lrt to be specified on the link line to access the timers,
- * so this needs to be checked for.
- *
- * It is worse because some libraries define __GLIBC__ but don't
- * support the version testing macro (e.g. uClibc).  This means
- * an extra check is needed.
- *
- * The final condition is:
- *      "have posix timers and either not glibc or glibc without -lrt"
- *
- * The nested #if sequences are required to avoid using a parameterised
- * macro that might be undefined.
- */
-#undef OSSL_POSIX_TIMER_OKAY
-#if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
-# if defined(__GLIBC__)
-#  if defined(__GLIBC_PREREQ)
-#   if __GLIBC_PREREQ(2, 17)
-#    define OSSL_POSIX_TIMER_OKAY
-#   endif
-#  endif
-# else
-#  define OSSL_POSIX_TIMER_OKAY
-# endif
-#endif
-
 #ifndef OPENSSL_NO_ENGINE
 /* non-NULL if default_RAND_meth is ENGINE-provided */
 static ENGINE *funct_ref;
@@ -69,6 +28,11 @@ static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
 
 int rand_fork_count;
 
+static CRYPTO_RWLOCK *rand_nonce_lock;
+static int rand_nonce_count;
+
+static int rand_cleaning_up = 0;
+
 #ifdef OPENSSL_RAND_SEED_RDTSC
 /*
  * IMPORTANT NOTE:  It is not currently possible to use this code
@@ -125,7 +89,7 @@ size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool)
     size_t bytes_needed;
     unsigned char *buffer;
 
-    bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
+    bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
     if (bytes_needed > 0) {
         buffer = rand_pool_add_begin(pool, bytes_needed);
 
@@ -182,21 +146,17 @@ size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
         return 0;
     }
 
-    pool = rand_pool_new(entropy, min_len, max_len);
-    if (pool == NULL)
-        return 0;
-
-    if (drbg->pool) {
-        rand_pool_add(pool,
-                      rand_pool_buffer(drbg->pool),
-                      rand_pool_length(drbg->pool),
-                      rand_pool_entropy(drbg->pool));
-        rand_pool_free(drbg->pool);
-        drbg->pool = NULL;
+    if (drbg->pool != NULL) {
+        pool = drbg->pool;
+        pool->entropy_requested = entropy;
+    } else {
+        pool = rand_pool_new(entropy, min_len, max_len);
+        if (pool == NULL)
+            return 0;
     }
 
     if (drbg->parent) {
-        size_t bytes_needed = rand_pool_bytes_needed(pool, 8);
+        size_t bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
         unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);
 
         if (buffer != NULL) {
@@ -212,8 +172,10 @@ size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
             if (RAND_DRBG_generate(drbg->parent,
                                    buffer, bytes_needed,
                                    prediction_resistance,
-                                   (unsigned char *)drbg, sizeof(*drbg)) != 0)
+                                   NULL, 0) != 0)
                 bytes = bytes_needed;
+            drbg->reseed_next_counter
+                = tsan_load(&drbg->parent->reseed_prop_counter);
             rand_drbg_unlock(drbg->parent);
 
             rand_pool_add_end(pool, bytes, 8 * bytes);
@@ -229,7 +191,7 @@ size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
              */
             RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY,
                     RAND_R_PREDICTION_RESISTANCE_NOT_SUPPORTED);
-            return 0;
+            goto err;
         }
 
         /* Get entropy by polling system entropy sources. */
@@ -241,77 +203,75 @@ size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
         *pout = rand_pool_detach(pool);
     }
 
+ err:
+    /* we need to reset drbg->pool in the error case */
+    if (ret == 0 && drbg->pool != NULL)
+        drbg->pool = NULL;
+
     rand_pool_free(pool);
     return ret;
 }
 
 /*
- * Find a suitable source of time.  Start with the highest resolution source
- * and work down to the slower ones.  This is added as additional data and
- * isn't counted as randomness, so any result is acceptable.
+ * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
  *
- * Returns 0 when we weren't able to find any time source
  */
-static uint64_t get_timer_bits(void)
+void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
+                               unsigned char *out, size_t outlen)
 {
-    uint64_t res = OPENSSL_rdtsc();
+    if (drbg->pool == NULL)
+        OPENSSL_secure_clear_free(out, outlen);
+    else
+        drbg->pool = NULL;
+}
 
-    if (res != 0)
-        return res;
-#if defined(_WIN32)
-    {
-        LARGE_INTEGER t;
-        FILETIME ft;
 
-        if (QueryPerformanceCounter(&t) != 0)
-            return t.QuadPart;
-        GetSystemTimeAsFileTime(&ft);
-        return TWO32TO64(ft.dwHighDateTime, ft.dwLowDateTime);
-    }
-#elif defined(__sun) || defined(__hpux)
-    return gethrtime();
-#elif defined(_AIX)
-    {
-        timebasestruct_t t;
-
-        read_wall_time(&t, TIMEBASE_SZ);
-        return TWO32TO64(t.tb_high, t.tb_low);
-    }
-#else
+/*
+ * Implements the get_nonce() callback (see RAND_DRBG_set_callbacks())
+ *
+ */
+size_t rand_drbg_get_nonce(RAND_DRBG *drbg,
+                           unsigned char **pout,
+                           int entropy, size_t min_len, size_t max_len)
+{
+    size_t ret = 0;
+    RAND_POOL *pool;
 
-# if defined(OSSL_POSIX_TIMER_OKAY)
-    {
-        struct timespec ts;
-        clockid_t cid;
-
-#  ifdef CLOCK_BOOTTIME
-        cid = CLOCK_BOOTTIME;
-#  elif defined(_POSIX_MONOTONIC_CLOCK)
-        cid = CLOCK_MONOTONIC;
-#  else
-        cid = CLOCK_REALTIME;
-#  endif
-
-        if (clock_gettime(cid, &ts) == 0)
-            return TWO32TO64(ts.tv_sec, ts.tv_nsec);
-    }
-# endif
-# if defined(__unix__) \
-     || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
-    {
-        struct timeval tv;
-
-        if (gettimeofday(&tv, NULL) == 0)
-            return TWO32TO64(tv.tv_sec, tv.tv_usec);
-    }
-# endif
-    {
-        time_t t = time(NULL);
-        if (t == (time_t)-1)
-            return 0;
-        return t;
-    }
-#endif
+    struct {
+        void * instance;
+        int count;
+    } data = { 0 };
+
+    pool = rand_pool_new(0, min_len, max_len);
+    if (pool == NULL)
+        return 0;
+
+    if (rand_pool_add_nonce_data(pool) == 0)
+        goto err;
+
+    data.instance = drbg;
+    CRYPTO_atomic_add(&rand_nonce_count, 1, &data.count, rand_nonce_lock);
+
+    if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
+        goto err;
+
+    ret   = rand_pool_length(pool);
+    *pout = rand_pool_detach(pool);
+
+ err:
+    rand_pool_free(pool);
+
+    return ret;
+}
+
+/*
+ * Implements the cleanup_nonce() callback (see RAND_DRBG_set_callbacks())
+ *
+ */
+void rand_drbg_cleanup_nonce(RAND_DRBG *drbg,
+                             unsigned char *out, size_t outlen)
+{
+    OPENSSL_secure_clear_free(out, outlen);
 }
 
 /*
@@ -326,86 +286,96 @@ static uint64_t get_timer_bits(void)
  */
 size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)
 {
+    size_t ret = 0;
     RAND_POOL *pool;
-    CRYPTO_THREAD_ID thread_id;
-    size_t len;
-#ifdef OPENSSL_SYS_UNIX
-    pid_t pid;
-#elif defined(OPENSSL_SYS_WIN32)
-    DWORD pid;
-#endif
-    uint64_t tbits;
 
     pool = rand_pool_new(0, 0, max_len);
     if (pool == NULL)
         return 0;
 
-#ifdef OPENSSL_SYS_UNIX
-    pid = getpid();
-    rand_pool_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
-#elif defined(OPENSSL_SYS_WIN32)
-    pid = GetCurrentProcessId();
-    rand_pool_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
-#endif
-
-    thread_id = CRYPTO_THREAD_get_current_id();
-    if (thread_id != 0)
-        rand_pool_add(pool, (unsigned char *)&thread_id, sizeof(thread_id), 0);
-
-    tbits = get_timer_bits();
-    if (tbits != 0)
-        rand_pool_add(pool, (unsigned char *)&tbits, sizeof(tbits), 0);
+    if (rand_pool_add_additional_data(pool) == 0)
+        goto err;
 
-    /* TODO: Use RDSEED? */
+    ret = rand_pool_length(pool);
+    *pout = rand_pool_detach(pool);
 
-    len = rand_pool_length(pool);
-    if (len != 0)
-        *pout = rand_pool_detach(pool);
+ err:
     rand_pool_free(pool);
 
-    return len;
+    return ret;
 }
 
-/*
- * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
- *
- */
-void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
-                               unsigned char *out, size_t outlen)
+void rand_drbg_cleanup_additional_data(unsigned char *out, size_t outlen)
 {
     OPENSSL_secure_clear_free(out, outlen);
 }
 
-void rand_fork()
+void rand_fork(void)
 {
     rand_fork_count++;
 }
 
 DEFINE_RUN_ONCE_STATIC(do_rand_init)
 {
-    int ret = 1;
-
 #ifndef OPENSSL_NO_ENGINE
     rand_engine_lock = CRYPTO_THREAD_lock_new();
-    ret &= rand_engine_lock != NULL;
+    if (rand_engine_lock == NULL)
+        return 0;
 #endif
+
     rand_meth_lock = CRYPTO_THREAD_lock_new();
-    ret &= rand_meth_lock != NULL;
+    if (rand_meth_lock == NULL)
+        goto err1;
 
-    return ret;
+    rand_nonce_lock = CRYPTO_THREAD_lock_new();
+    if (rand_nonce_lock == NULL)
+        goto err2;
+
+    if (!rand_cleaning_up && !rand_pool_init())
+        goto err3;
+
+    return 1;
+
+err3:
+    rand_pool_cleanup();
+err2:
+    CRYPTO_THREAD_lock_free(rand_meth_lock);
+    rand_meth_lock = NULL;
+err1:
+#ifndef OPENSSL_NO_ENGINE
+    CRYPTO_THREAD_lock_free(rand_engine_lock);
+    rand_engine_lock = NULL;
+#endif
+    return 0;
 }
 
 void rand_cleanup_int(void)
 {
     const RAND_METHOD *meth = default_RAND_meth;
 
+    rand_cleaning_up = 1;
+
     if (meth != NULL && meth->cleanup != NULL)
         meth->cleanup();
     RAND_set_rand_method(NULL);
+    rand_pool_cleanup();
 #ifndef OPENSSL_NO_ENGINE
     CRYPTO_THREAD_lock_free(rand_engine_lock);
+    rand_engine_lock = NULL;
 #endif
     CRYPTO_THREAD_lock_free(rand_meth_lock);
+    rand_meth_lock = NULL;
+    CRYPTO_THREAD_lock_free(rand_nonce_lock);
+    rand_nonce_lock = NULL;
+}
+
+/*
+ * RAND_close_seed_files() ensures that any seed file decriptors are
+ * closed after use.
+ */
+void RAND_keep_random_devices_open(int keep)
+{
+    rand_pool_keep_random_devices_open(keep);
 }
 
 /*
@@ -440,7 +410,7 @@ int RAND_poll(void)
         /* fill random pool and seed the current legacy RNG */
         pool = rand_pool_new(RAND_DRBG_STRENGTH,
                              RAND_DRBG_STRENGTH / 8,
-                             DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));
+                             RAND_POOL_MAX_LENGTH);
         if (pool == NULL)
             return 0;
 
@@ -465,17 +435,18 @@ err:
  * Allocate memory and initialize a new random pool
  */
 
-RAND_POOL *rand_pool_new(int entropy, size_t min_len, size_t max_len)
+RAND_POOL *rand_pool_new(int entropy_requested, size_t min_len, size_t max_len)
 {
     RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
 
     if (pool == NULL) {
         RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
-        goto err;
+        return NULL;
     }
 
     pool->min_len = min_len;
-    pool->max_len = max_len;
+    pool->max_len = (max_len > RAND_POOL_MAX_LENGTH) ?
+        RAND_POOL_MAX_LENGTH : max_len;
 
     pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
     if (pool->buffer == NULL) {
@@ -483,7 +454,7 @@ RAND_POOL *rand_pool_new(int entropy, size_t min_len, size_t max_len)
         goto err;
     }
 
-    pool->requested_entropy = entropy;
+    pool->entropy_requested = entropy_requested;
 
     return pool;
 
@@ -492,6 +463,38 @@ err:
     return NULL;
 }
 
+/*
+ * Attach new random pool to the given buffer
+ *
+ * This function is intended to be used only for feeding random data
+ * provided by RAND_add() and RAND_seed() into the <master> DRBG.
+ */
+RAND_POOL *rand_pool_attach(const unsigned char *buffer, size_t len,
+                            size_t entropy)
+{
+    RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
+
+    if (pool == NULL) {
+        RANDerr(RAND_F_RAND_POOL_ATTACH, ERR_R_MALLOC_FAILURE);
+        return NULL;
+    }
+
+    /*
+     * The const needs to be cast away, but attached buffers will not be
+     * modified (in contrary to allocated buffers which are zeroed and
+     * freed in the end).
+     */
+    pool->buffer = (unsigned char *) buffer;
+    pool->len = len;
+
+    pool->attached = 1;
+
+    pool->min_len = pool->max_len = pool->len;
+    pool->entropy = entropy;
+
+    return pool;
+}
+
 /*
  * Free |pool|, securely erasing its buffer.
  */
@@ -500,7 +503,14 @@ void rand_pool_free(RAND_POOL *pool)
     if (pool == NULL)
         return;
 
-    OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
+    /*
+     * Although it would be advisable from a cryptographical viewpoint,
+     * we are not allowed to clear attached buffers, since they are passed
+     * to rand_pool_attach() as `const unsigned char*`.
+     * (see corresponding comment in rand_pool_attach()).
+     */
+    if (!pool->attached)
+        OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
     OPENSSL_free(pool);
 }
 
@@ -542,11 +552,11 @@ unsigned char *rand_pool_detach(RAND_POOL *pool)
 
 
 /*
- * If every byte of the input contains |entropy_per_bytes| bits of entropy,
- * how many bytes does one need to obtain at least |bits| bits of entropy?
+ * If |entropy_factor| bits contain 1 bit of entropy, how many bytes does one
+ * need to obtain at least |bits| bits of entropy?
  */
-#define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
-    (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
+#define ENTROPY_TO_BYTES(bits, entropy_factor) \
+    (((bits) * (entropy_factor) + 7) / 8)
 
 
 /*
@@ -559,7 +569,7 @@ unsigned char *rand_pool_detach(RAND_POOL *pool)
  */
 size_t rand_pool_entropy_available(RAND_POOL *pool)
 {
-    if (pool->entropy < pool->requested_entropy)
+    if (pool->entropy < pool->entropy_requested)
         return 0;
 
     if (pool->len < pool->min_len)
@@ -575,29 +585,29 @@ size_t rand_pool_entropy_available(RAND_POOL *pool)
 
 size_t rand_pool_entropy_needed(RAND_POOL *pool)
 {
-    if (pool->entropy < pool->requested_entropy)
-        return pool->requested_entropy - pool->entropy;
+    if (pool->entropy < pool->entropy_requested)
+        return pool->entropy_requested - pool->entropy;
 
     return 0;
 }
 
 /*
  * Returns the number of bytes needed to fill the pool, assuming
- * the input has 'entropy_per_byte' entropy bits per byte.
+ * the input has 1 / |entropy_factor| entropy bits per data bit.
  * In case of an error, 0 is returned.
  */
 
-size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte)
+size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_factor)
 {
     size_t bytes_needed;
     size_t entropy_needed = rand_pool_entropy_needed(pool);
 
-    if (entropy_per_byte < 1 || entropy_per_byte > 8) {
+    if (entropy_factor < 1) {
         RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
         return 0;
     }
 
-    bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_per_byte);
+    bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_factor);
 
     if (bytes_needed > pool->max_len - pool->len) {
         /* not enough space left */