Place DRBG in error state if health check fails.
[openssl.git] / fips / rand / fips_drbg_lib.c
index 5564538540ef6d324896831b1b9cb50dfaa64a11..f5f365b01e327ace8d5feb311399f49a1109dcf7 100644 (file)
@@ -55,8 +55,6 @@
 
 #include <string.h>
 #include <openssl/crypto.h>
-#include <openssl/evp.h>
-#include <openssl/aes.h>
 #include <openssl/err.h>
 #include <openssl/fips_rand.h>
 #include "fips_rand_lcl.h"
@@ -71,10 +69,16 @@ int FIPS_drbg_init(DRBG_CTX *dctx, int type, unsigned int flags)
        dctx->flags = flags;
        dctx->type = type;
 
+       dctx->entropy_blocklen = 0;
+       dctx->health_check_cnt = 0;
+       dctx->health_check_interval = DRBG_HEALTH_INTERVAL;
+
        rv = fips_drbg_hash_init(dctx);
 
        if (rv == -2)
                rv = fips_drbg_ctr_init(dctx);
+       if (rv == -2)
+               rv = fips_drbg_hmac_init(dctx);
 
        if (rv <= 0)
                {
@@ -84,12 +88,24 @@ int FIPS_drbg_init(DRBG_CTX *dctx, int type, unsigned int flags)
                        FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_ERROR_INITIALISING_DRBG);
                }
 
+       /* If not in test mode run selftests on DRBG of the same type */
+
+       if (!(dctx->flags & DRBG_FLAG_TEST))
+               {
+               DRBG_CTX tctx;
+               if (!fips_drbg_kat(&tctx, type, flags | DRBG_FLAG_TEST))
+                       {
+                       FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_SELFTEST_FAILURE);
+                       dctx->status = DRBG_STATUS_ERROR;
+                       return 0;
+                       }
+               }
+
        return rv;
        }
 
 DRBG_CTX *FIPS_drbg_new(int type, unsigned int flags)
        {
-       int rv;
        DRBG_CTX *dctx;
        dctx = OPENSSL_malloc(sizeof(DRBG_CTX));
        if (!dctx)
@@ -99,7 +115,6 @@ DRBG_CTX *FIPS_drbg_new(int type, unsigned int flags)
                }
        if (type == 0)
                return dctx;
-       rv = FIPS_drbg_init(dctx, type, flags);
 
        if (FIPS_drbg_init(dctx, type, flags) <= 0)
                {
@@ -118,6 +133,46 @@ void FIPS_drbg_free(DRBG_CTX *dctx)
        OPENSSL_free(dctx);
        }
 
+static size_t fips_get_entropy(DRBG_CTX *dctx, unsigned char **pout,
+                               int entropy, size_t min_len, size_t max_len)
+       {
+       unsigned char *tout, *p;
+       size_t bl = dctx->entropy_blocklen, rv;
+       if (dctx->flags & DRBG_FLAG_TEST || !bl)
+               return dctx->get_entropy(dctx, pout, entropy, min_len, max_len);
+       rv = dctx->get_entropy(dctx, &tout, entropy + bl,
+                               min_len + bl, max_len + bl);
+       *pout = tout + bl;
+       if (rv < (min_len + bl) || (rv % bl))
+               return 0;
+       /* Compare consecutive blocks for continuous PRNG test */
+       for (p = tout; p < tout + rv - bl; p += bl)
+               {
+               if (!memcmp(p, p + bl, bl))
+                       {
+                       FIPSerr(FIPS_F_FIPS_GET_ENTROPY, FIPS_R_ENTROPY_SOURCE_STUCK);
+                       return 0;
+                       }
+               }
+       rv -= bl;
+       if (rv > max_len)
+               return max_len;
+       return rv;
+       }
+
+static void fips_cleanup_entropy(DRBG_CTX *dctx,
+                                       unsigned char *out, size_t olen)
+       {
+       size_t bl;
+       if (dctx->flags & DRBG_FLAG_TEST)
+               bl = 0;
+       else
+               bl = dctx->entropy_blocklen;
+       /* Call cleanup with original arguments */
+       dctx->cleanup_entropy(dctx, out - bl, olen + bl);
+       }
+
+
 int FIPS_drbg_instantiate(DRBG_CTX *dctx,
                                const unsigned char *pers, size_t perslen)
        {
@@ -154,7 +209,7 @@ int FIPS_drbg_instantiate(DRBG_CTX *dctx,
 
        dctx->status = DRBG_STATUS_ERROR;
 
-       entlen = dctx->get_entropy(dctx, &entropy, dctx->strength,
+       entlen = fips_get_entropy(dctx, &entropy, dctx->strength,
                                dctx->min_entropy, dctx->max_entropy);
 
        if (entlen < dctx->min_entropy || entlen > dctx->max_entropy)
@@ -193,7 +248,7 @@ int FIPS_drbg_instantiate(DRBG_CTX *dctx,
        end:
 
        if (entropy && dctx->cleanup_entropy)
-               dctx->cleanup_entropy(dctx, entropy, entlen);
+               fips_cleanup_entropy(dctx, entropy, entlen);
 
        if (nonce && dctx->cleanup_nonce)
                dctx->cleanup_nonce(dctx, nonce, noncelen);
@@ -239,7 +294,7 @@ int FIPS_drbg_reseed(DRBG_CTX *dctx,
 
        dctx->status = DRBG_STATUS_ERROR;
 
-       entlen = dctx->get_entropy(dctx, &entropy, dctx->strength,
+       entlen = fips_get_entropy(dctx, &entropy, dctx->strength,
                                dctx->min_entropy, dctx->max_entropy);
 
        if (entlen < dctx->min_entropy || entlen > dctx->max_entropy)
@@ -256,7 +311,7 @@ int FIPS_drbg_reseed(DRBG_CTX *dctx,
        end:
 
        if (entropy && dctx->cleanup_entropy)
-               dctx->cleanup_entropy(dctx, entropy, entlen);
+               fips_cleanup_entropy(dctx, entropy, entlen);
 
        if (dctx->status == DRBG_STATUS_READY)
                return 1;
@@ -267,14 +322,35 @@ int FIPS_drbg_reseed(DRBG_CTX *dctx,
        return 0;
        }
 
+static int fips_drbg_check(DRBG_CTX *dctx)
+       {
+       if (dctx->flags & DRBG_FLAG_TEST)
+               return 1;
+       dctx->health_check_cnt++;
+       if (dctx->health_check_cnt >= dctx->health_check_interval)
+               {
+               DRBG_CTX tctx;
+               if (!fips_drbg_kat(&tctx, dctx->type,
+                                               dctx->flags | DRBG_FLAG_TEST))
+                       {
+                       FIPSerr(FIPS_F_FIPS_DRBG_CHECK, FIPS_R_SELFTEST_FAILURE);
+                       dctx->status = DRBG_STATUS_ERROR;
+                       return 0;
+                       }
+               dctx->health_check_cnt = 0;
+               }
+       return 1;
+       }
 
-static int fips_drbg_generate_internal(DRBG_CTX *dctx,
-                       unsigned char *out, size_t outlen,
+int FIPS_drbg_generate(DRBG_CTX *dctx, unsigned char *out, size_t outlen,
                        int strength, int prediction_resistance,
                        const unsigned char *adin, size_t adinlen)
        {
        int r = 0;
 
+       if (!fips_drbg_check(dctx))
+               return 0;
+
        if (dctx->status != DRBG_STATUS_READY
                && dctx->status != DRBG_STATUS_RESEED)
                {
@@ -323,76 +399,13 @@ static int fips_drbg_generate_internal(DRBG_CTX *dctx,
        if (r)
                {
                if (!(dctx->flags & DRBG_FLAG_NOERR))
-                       FIPSerr(FIPS_F_FIPS_DRBG_GENERATE_INTERNAL, r);
+                       FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, r);
                return 0;
                }
 
        return 1;
        }
 
-/* external generate function: incorporates continuous RNG test if not
- * in test mode.
- */
-
-int FIPS_drbg_generate(DRBG_CTX *dctx,
-                       unsigned char *out, size_t outlen,
-                       int strength, int prediction_resistance,
-                       const unsigned char *adin, size_t adinlen)
-       {
-       unsigned char tmp[16], *pout;
-       size_t poutlen;
-       /* If test mode don't run continuous RNG test */
-       if (dctx->flags & DRBG_FLAG_TEST)
-               {
-               return fips_drbg_generate_internal(dctx, out, outlen,
-                                                       strength,
-                                                       prediction_resistance,
-                                                       adin, adinlen);
-               }
-       /* If this is the first call generate block and save buffer */
-       if (!dctx->lb_valid)
-               {
-               if (!fips_drbg_generate_internal(dctx, dctx->lb, 16,
-                                               strength, prediction_resistance,
-                                               adin, adinlen))
-                       return 0;
-               dctx->lb_valid = 1;
-               }
-
-       /* If request less that 16 bytes request 16 in temp buffer */
-
-       if (outlen < 16)
-               {
-               pout = tmp;
-               poutlen = 16;
-               }
-       else
-               {
-               pout = out;
-               poutlen = outlen;
-               }
-
-       /* Generate data */
-       if (!fips_drbg_generate_internal(dctx, pout, poutlen,
-                                               strength, prediction_resistance,
-                                               adin, adinlen))
-                       return 0;
-       /* Compare to last block for continuous PRNG test */
-       if (!memcmp(pout, dctx->lb, 16))
-               {
-               FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, FIPS_R_DRBG_STUCK);
-               return 0;
-               }
-       /* Update last block */
-       memcpy(dctx->lb, pout, 16);
-       /* Copy to output buffer if needed */
-       if (outlen < 16)
-               memcpy(out, pout, outlen);
-
-       return 1;
-
-       }
-
 int FIPS_drbg_uninstantiate(DRBG_CTX *dctx)
        {
        int rv;
@@ -413,12 +426,14 @@ int FIPS_drbg_set_callbacks(DRBG_CTX *dctx,
        size_t (*get_entropy)(DRBG_CTX *ctx, unsigned char **pout,
                                int entropy, size_t min_len, size_t max_len),
        void (*cleanup_entropy)(DRBG_CTX *ctx, unsigned char *out, size_t olen),
+       size_t entropy_blocklen,
        size_t (*get_nonce)(DRBG_CTX *ctx, unsigned char **pout,
                                int entropy, size_t min_len, size_t max_len),
        void (*cleanup_nonce)(DRBG_CTX *ctx, unsigned char *out, size_t olen))
        {
        if (dctx->status != DRBG_STATUS_UNINITIALISED)
                return 0;
+       dctx->entropy_blocklen = entropy_blocklen;
        dctx->get_entropy = get_entropy;
        dctx->cleanup_entropy = cleanup_entropy;
        dctx->get_nonce = get_nonce;
@@ -461,3 +476,42 @@ int FIPS_drbg_get_strength(DRBG_CTX *dctx)
        {
        return dctx->strength;
        }
+
+void FIPS_drbg_set_check_interval(DRBG_CTX *dctx, int interval)
+       {
+       dctx->health_check_interval = interval;
+       }
+
+static int drbg_stick = 0;
+
+void FIPS_drbg_stick(void)
+       {
+       drbg_stick = 1;
+       }
+
+/* Continuous DRBG utility function */
+int fips_drbg_cprng_test(DRBG_CTX *dctx, const unsigned char *out)
+       {
+       /* No CPRNG in test mode */
+       if (dctx->flags & DRBG_FLAG_TEST)
+               return 1;
+       /* Check block is valid: should never happen */
+       if (dctx->lb_valid == 0)
+               {
+               FIPSerr(FIPS_F_FIPS_DRBG_CPRNG_TEST, FIPS_R_INTERNAL_ERROR);
+               fips_set_selftest_fail();
+               return 0;
+               }
+       if (drbg_stick)
+               memcpy(dctx->lb, out, dctx->blocklength);
+       /* Check against last block: fail if match */
+       if (!memcmp(dctx->lb, out, dctx->blocklength))
+               {
+               FIPSerr(FIPS_F_FIPS_DRBG_CPRNG_TEST, FIPS_R_DRBG_STUCK);
+               fips_set_selftest_fail();
+               return 0;
+               }
+       /* Save last block for next comparison */
+       memcpy(dctx->lb, out, dctx->blocklength);
+       return 1;
+       }