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 837947e8a622c90307c1f12336f987c424cddcaf..6d7f37e15e648c659de7c3d88bf49d95f75bfbe5 100644 (file)
--- a/crypto/rand/md_rand.c
+++ b/crypto/rand/md_rand.c
@@ -119,7 +119,7 @@
 #include <stdio.h>
 #include <string.h>
 
 #include <stdio.h>
 #include <string.h>
 

-#include "openssl/e_os.h"
+#include "e_os.h"

 
 #include <openssl/rand.h>
 #include "rand_lcl.h"
 
 #include <openssl/rand.h>
 #include "rand_lcl.h"


@@ -141,10 +141,12 @@ static long md_count[2]={0,0};
 static double entropy=0;
 static int initialized=0;
 
 static double entropy=0;
 static int initialized=0;
 

-/* This should be set to 1 only when ssleay_rand_add() is called inside
-   an already locked state, so it doesn't try to lock and thereby cause
-   a hang.  And it should always be reset back to 0 before unlocking. */
-static int add_do_not_lock=0;
+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 */
+

 
 #ifdef PREDICT
 int rand_predictable=0;
 
 #ifdef PREDICT
 int rand_predictable=0;


@@ -182,6 +184,7 @@ static void ssleay_rand_cleanup(void)
        md_count[0]=0;
        md_count[1]=0;
        entropy=0;
        md_count[0]=0;
        md_count[1]=0;
        entropy=0;

+       initialized=0;

        }
 
 static void ssleay_rand_add(const void *buf, int num, double add)
        }
 
 static void ssleay_rand_add(const void *buf, int num, double add)


@@ -190,6 +193,7 @@ static void ssleay_rand_add(const void *buf, int num, double add)
        long md_c[2];
        unsigned char local_md[MD_DIGEST_LENGTH];
        MD_CTX m;
        long md_c[2];
        unsigned char local_md[MD_DIGEST_LENGTH];
        MD_CTX m;

+       int do_not_lock;

 
        /*
         * (Based on the rand(3) manpage)
 
        /*
         * (Based on the rand(3) manpage)


@@ -206,7 +210,17 @@ static void ssleay_rand_add(const void *buf, int num, double add)
          * hash function.
         */
 
          * hash function.
         */
 

-       if (!add_do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
+       /* check if we already have the lock */
+       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;
 
        /* use our own copies of the counters so that even
        st_idx=state_index;
 
        /* use our own copies of the counters so that even


@@ -238,7 +252,7 @@ static void ssleay_rand_add(const void *buf, int num, double add)
 
        md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
 
 
        md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);
 

-       if (!add_do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
+       if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

 
        for (i=0; i<num; i+=MD_DIGEST_LENGTH)
                {
 
        for (i=0; i<num; i+=MD_DIGEST_LENGTH)
                {


@@ -258,7 +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;


@@ -280,7 +294,7 @@ static void ssleay_rand_add(const void *buf, int num, double add)
                }
        memset((char *)&m,0,sizeof(m));
 
                }
        memset((char *)&m,0,sizeof(m));
 

-       if (!add_do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);
+       if (!do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);

        /* Don't just copy back local_md into md -- this could mean that
         * other thread's seeding remains without effect (except for
         * the incremented counter).  By XORing it we keep at least as
        /* Don't just copy back local_md into md -- this could mean that
         * other thread's seeding remains without effect (except for
         * the incremented counter).  By XORing it we keep at least as


@@ -291,9 +305,9 @@ static void ssleay_rand_add(const void *buf, int num, double add)
                }
        if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
            entropy += add;
                }
        if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
            entropy += add;

-       if (!add_do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
+       if (!do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

        
        

-#if !defined(THREADS) && !defined(WIN32)
+#if !defined(OPENSSL_THREADS) && !defined(OPENSSL_SYS_WIN32)

        assert(md_c[1] == md_count[1]);
 #endif
        }
        assert(md_c[1] == md_count[1]);
 #endif
        }


@@ -307,6 +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];


@@ -327,33 +342,44 @@ 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
         * global 'md'.
         */
 
         * 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
         * global 'md'.
         */
 

-       if (!initialized)
-               RAND_poll();
-

        CRYPTO_w_lock(CRYPTO_LOCK_RAND);
        CRYPTO_w_lock(CRYPTO_LOCK_RAND);

-       add_do_not_lock = 1;    /* Since we call ssleay_rand_add while in
-                                  this locked state. */

 
 

-       initialized = 1;
+       /* prevent ssleay_rand_bytes() from trying to obtain the lock again */
+       CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
+       locking_thread = CRYPTO_thread_id();
+       CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
+       crypto_lock_rand = 1;
+
+       if (!initialized)
+               {
+               RAND_poll();
+               initialized = 1;
+               }
+       

        if (!stirred_pool)
                do_stir_pool = 1;
        
        if (!stirred_pool)
                do_stir_pool = 1;
        


@@ -379,11 +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 */


@@ -408,21 +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;
 
         * are now ours (but other threads may use them too) */
 
        md_count[0] += 1;
 

-       add_do_not_lock = 0;    /* If this would ever be forgotten, we can
-                                  expect any evil god to eat our souls. */
+       /* before unlocking, we must clear 'crypto_lock_rand' */
+       crypto_lock_rand = 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);


@@ -433,27 +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];

                        }
                }
 
                        }
                }
 


@@ -462,7 +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));


@@ -481,7 +509,8 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
    unpredictable */
 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num) 
        {
    unpredictable */
 static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num) 
        {

-       int ret, err;
+       int ret;
+       unsigned long err;

 
        ret = RAND_bytes(buf, num);
        if (ret == 0)
 
        ret = RAND_bytes(buf, num);
        if (ret == 0)


@@ -497,14 +526,45 @@ static int ssleay_rand_pseudo_bytes(unsigned char *buf, int num)
 static int ssleay_rand_status(void)
        {
        int ret;
 static int ssleay_rand_status(void)
        {
        int ret;

+       int do_not_lock;

 
 

+       /* check if we already have the lock
+        * (could happen if a RAND_poll() implementation calls RAND_status()) */
+       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 */
+               CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
+               locking_thread = CRYPTO_thread_id();
+               CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
+               crypto_lock_rand = 1;
+               }
+       

        if (!initialized)
        if (!initialized)

+               {

                RAND_poll();
                RAND_poll();

+               initialized = 1;
+               }

 
 

-       CRYPTO_w_lock(CRYPTO_LOCK_RAND);
-       initialized = 1;

        ret = entropy >= ENTROPY_NEEDED;
        ret = entropy >= ENTROPY_NEEDED;

-       CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

 
 

+       if (!do_not_lock)
+               {
+               /* before unlocking, we must clear 'crypto_lock_rand' */
+               crypto_lock_rand = 0;
+               
+               CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
+               }
+       

        return ret;
        }
        return ret;
        }