md_rand.c thread safety

[openssl.git] / crypto / rand / md_rand.c

diff --git a/crypto/rand/md_rand.c b/crypto/rand/md_rand.c
index d4d2f36ad4f2acf998d93b6bcc7c44b26c8fcc67..6d7f37e15e648c659de7c3d88bf49d95f75bfbe5 100644 (file)
--- a/crypto/rand/md_rand.c
+++ b/crypto/rand/md_rand.c
@@ -144,6 +144,7 @@ static int initialized=0;
 static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
                                            * holds CRYPTO_LOCK_RAND
                                            * (to prevent double locking) */
 static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
                                            * holds CRYPTO_LOCK_RAND
                                            * (to prevent double locking) */

+/* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */

 static unsigned long locking_thread = 0; /* valid iff crypto_lock_rand is set */
 
 
 static unsigned long locking_thread = 0; /* valid iff crypto_lock_rand is set */
 
 


@@ -210,7 +211,14 @@ static void ssleay_rand_add(const void *buf, int num, double add)
         */
 
        /* check if we already have the lock */
         */
 
        /* check if we already have the lock */

-       do_not_lock = crypto_lock_rand && (locking_thread == CRYPTO_thread_id());
+       if (crypto_lock_rand)
+               {
+               CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
+               do_not_lock = (locking_thread == CRYPTO_thread_id());
+               CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
+               }
+       else
+               do_not_lock = 0;

 
        if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
        st_idx=state_index;
 
        if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
        st_idx=state_index;


@@ -264,7 +272,7 @@ static void ssleay_rand_add(const void *buf, int num, double add)
                        
                MD_Update(&m,buf,j);
                MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
                        
                MD_Update(&m,buf,j);
                MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));

-               MD_Final(local_md,&m);
+               MD_Final(&m,local_md);

                md_c[1]++;
 
                buf=(const char *)buf + j;
                md_c[1]++;
 
                buf=(const char *)buf + j;


@@ -313,6 +321,7 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
        {
        static volatile int stirred_pool = 0;
        int i,j,k,st_num,st_idx;
        {
        static volatile int stirred_pool = 0;
        int i,j,k,st_num,st_idx;

+       int num_ceil;

        int ok;
        long md_c[2];
        unsigned char local_md[MD_DIGEST_LENGTH];
        int ok;
        long md_c[2];
        unsigned char local_md[MD_DIGEST_LENGTH];


@@ -333,19 +342,24 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
                }
 #endif
 
                }
 #endif
 

+       if (num <= 0)
+               return 1;
+       
+       /* round upwards to multiple of MD_DIGEST_LENGTH/2 */
+       num_ceil = (1 + (num-1)/(MD_DIGEST_LENGTH/2)) * (MD_DIGEST_LENGTH/2);
+

        /*
         * (Based on the rand(3) manpage:)
         *
         * For each group of 10 bytes (or less), we do the following:
         *
        /*
         * (Based on the rand(3) manpage:)
         *
         * For each group of 10 bytes (or less), we do the following:
         *

-        * Input into the hash function the top 10 bytes from the
-        * local 'md' (which is initialized from the global 'md'
-        * before any bytes are generated), the bytes that are
-        * to be overwritten by the random bytes, and bytes from the
-        * 'state' (incrementing looping index).  From this digest output
-        * (which is kept in 'md'), the top (up to) 10 bytes are
-        * returned to the caller and the bottom (up to) 10 bytes are xored
-        * into the 'state'.
+        * Input into the hash function the local 'md' (which is initialized from
+        * the global 'md' before any bytes are generated), the bytes that are to
+        * be overwritten by the random bytes, and bytes from the 'state'
+        * (incrementing looping index). From this digest output (which is kept
+        * in 'md'), the top (up to) 10 bytes are returned to the caller and the
+        * bottom 10 bytes are xored into the 'state'.
+        * 

         * Finally, after we have finished 'num' random bytes for the
         * caller, 'count' (which is incremented) and the local and global 'md'
         * are fed into the hash function and the results are kept in the
         * Finally, after we have finished 'num' random bytes for the
         * caller, 'count' (which is incremented) and the local and global 'md'
         * are fed into the hash function and the results are kept in the


@@ -355,8 +369,10 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
        CRYPTO_w_lock(CRYPTO_LOCK_RAND);
 
        /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
        CRYPTO_w_lock(CRYPTO_LOCK_RAND);
 
        /* prevent ssleay_rand_bytes() from trying to obtain the lock again */

-       crypto_lock_rand = 1;
+       CRYPTO_w_lock(CRYPTO_LOCK_RAND2);

        locking_thread = CRYPTO_thread_id();
        locking_thread = CRYPTO_thread_id();

+       CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
+       crypto_lock_rand = 1;

 
        if (!initialized)
                {
 
        if (!initialized)
                {


@@ -389,11 +405,11 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
 
        if (do_stir_pool)
                {
 
        if (do_stir_pool)
                {

-               /* Our output function chains only half of 'md', so we better
-                * make sure that the required entropy gets 'evenly distributed'
-                * through 'state', our randomness pool.  The input function
-                * (ssleay_rand_add) chains all of 'md', which makes it more
-                * suitable for this purpose.
+               /* In the output function only half of 'md' remains secret,
+                * so we better make sure that the required entropy gets
+                * 'evenly distributed' through 'state', our randomness pool.
+                * The input function (ssleay_rand_add) chains all of 'md',
+                * which makes it more suitable for this purpose.

                 */
 
                int n = STATE_SIZE; /* so that the complete pool gets accessed */
                 */
 
                int n = STATE_SIZE; /* so that the complete pool gets accessed */


@@ -418,22 +434,22 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
        md_c[1] = md_count[1];
        memcpy(local_md, md, sizeof md);
 
        md_c[1] = md_count[1];
        memcpy(local_md, md, sizeof md);
 

-       state_index+=num;
+       state_index+=num_ceil;

        if (state_index > state_num)
                state_index %= state_num;
 
        if (state_index > state_num)
                state_index %= state_num;
 

-       /* state[st_idx], ..., state[(st_idx + num - 1) % st_num]
+       /* state[st_idx], ..., state[(st_idx + num_ceil - 1) % st_num]

         * are now ours (but other threads may use them too) */
 
        md_count[0] += 1;
 
        /* before unlocking, we must clear 'crypto_lock_rand' */
        crypto_lock_rand = 0;
         * are now ours (but other threads may use them too) */
 
        md_count[0] += 1;
 
        /* before unlocking, we must clear 'crypto_lock_rand' */
        crypto_lock_rand = 0;

-       locking_thread = 0;

        CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
 
        while (num > 0)
                {
        CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
 
        while (num > 0)
                {

+               /* num_ceil -= MD_DIGEST_LENGTH/2 */

                j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
                num-=j;
                MD_Init(&m);
                j=(num >= MD_DIGEST_LENGTH/2)?MD_DIGEST_LENGTH/2:num;
                num-=j;
                MD_Init(&m);


@@ -444,27 +460,28 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
                        curr_pid = 0;
                        }
 #endif
                        curr_pid = 0;
                        }
 #endif

-               MD_Update(&m,&(local_md[MD_DIGEST_LENGTH/2]),MD_DIGEST_LENGTH/2);
+               MD_Update(&m,local_md,MD_DIGEST_LENGTH);

                MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
 #ifndef PURIFY
                MD_Update(&m,buf,j); /* purify complains */
 #endif
                MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
 #ifndef PURIFY
                MD_Update(&m,buf,j); /* purify complains */
 #endif

-               k=(st_idx+j)-st_num;
+               k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;

                if (k > 0)
                        {
                if (k > 0)
                        {

-                       MD_Update(&m,&(state[st_idx]),j-k);
+                       MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2-k);

                        MD_Update(&m,&(state[0]),k);
                        }
                else
                        MD_Update(&m,&(state[0]),k);
                        }
                else

-                       MD_Update(&m,&(state[st_idx]),j);
-               MD_Final(local_md,&m);
+                       MD_Update(&m,&(state[st_idx]),MD_DIGEST_LENGTH/2);
+               MD_Final(&m,local_md);

 
 

-               for (i=0; i<j; i++)
+               for (i=0; i<MD_DIGEST_LENGTH/2; i++)

                        {
                        state[st_idx++]^=local_md[i]; /* may compete with other threads */
                        {
                        state[st_idx++]^=local_md[i]; /* may compete with other threads */

-                       *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];

                        if (st_idx >= st_num)
                                st_idx=0;
                        if (st_idx >= st_num)
                                st_idx=0;

+                       if (i < j)
+                               *(buf++)=local_md[i+MD_DIGEST_LENGTH/2];

                        }
                }
 
                        }
                }
 


@@ -473,7 +490,7 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
        MD_Update(&m,local_md,MD_DIGEST_LENGTH);
        CRYPTO_w_lock(CRYPTO_LOCK_RAND);
        MD_Update(&m,md,MD_DIGEST_LENGTH);
        MD_Update(&m,local_md,MD_DIGEST_LENGTH);
        CRYPTO_w_lock(CRYPTO_LOCK_RAND);
        MD_Update(&m,md,MD_DIGEST_LENGTH);

-       MD_Final(md,&m);
+       MD_Final(&m,md);

        CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
 
        memset(&m,0,sizeof(m));
        CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
 
        memset(&m,0,sizeof(m));


@@ -513,15 +530,24 @@ static int ssleay_rand_status(void)
 
        /* check if we already have the lock
         * (could happen if a RAND_poll() implementation calls RAND_status()) */
 
        /* check if we already have the lock
         * (could happen if a RAND_poll() implementation calls RAND_status()) */

-       do_not_lock = crypto_lock_rand && (locking_thread == CRYPTO_thread_id());
+       if (crypto_lock_rand)
+               {
+               CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
+               do_not_lock = (locking_thread == CRYPTO_thread_id());
+               CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
+               }
+       else
+               do_not_lock = 0;

        
        if (!do_not_lock)
                {
                CRYPTO_w_lock(CRYPTO_LOCK_RAND);
                
                /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
        
        if (!do_not_lock)
                {
                CRYPTO_w_lock(CRYPTO_LOCK_RAND);
                
                /* prevent ssleay_rand_bytes() from trying to obtain the lock again */

-               crypto_lock_rand = 1;
+               CRYPTO_w_lock(CRYPTO_LOCK_RAND2);

                locking_thread = CRYPTO_thread_id();
                locking_thread = CRYPTO_thread_id();

+               CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
+               crypto_lock_rand = 1;

                }
        
        if (!initialized)
                }
        
        if (!initialized)


@@ -536,7 +562,6 @@ static int ssleay_rand_status(void)
                {
                /* before unlocking, we must clear 'crypto_lock_rand' */
                crypto_lock_rand = 0;
                {
                /* before unlocking, we must clear 'crypto_lock_rand' */
                crypto_lock_rand = 0;

-               locking_thread = 0;

                
                CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
                }
                
                CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
                }