r1492: Rework our random number generation system.

On systems with /dev/urandom, this avoids a change to secrets.tdb for every fork().

For other systems, we now only re-seed after a fork, and on startup.
No need to do it per-operation.  This removes the 'need_reseed'
parameter from generate_random_buffer().

Andrew Bartlett
(This used to be commit 36741d3cf53a7bd17d361251f2bb50851cdb035f)

19 files changed, 82 insertions, 71 deletions

diff --git a/source3/auth/auth.c b/source3/auth/auth.c
index 1b49699fbc..7cfe3fc639 100644
--- a/source3/auth/auth.c
+++ b/source3/auth/auth.c
@@ -124,7 +124,7 @@ static const uint8 *get_ntlm_challenge(struct auth_context *auth_context)
 	if (!challenge_set_by) {
 		uchar chal[8];
 		
-		generate_random_buffer(chal, sizeof(chal), False);
+		generate_random_buffer(chal, sizeof(chal));
 		auth_context->challenge = data_blob_talloc(auth_context->mem_ctx, 
 							   chal, sizeof(chal));
 		
diff --git a/source3/lib/afs.c b/source3/lib/afs.c
index 0830a3a0e7..8688fde6b1 100644
--- a/source3/lib/afs.c
+++ b/source3/lib/afs.c
@@ -116,7 +116,7 @@ static BOOL afs_createtoken(const char *username, const char *cell,
 	p += 4;
 
 	/* We need to create a session key */
-	generate_random_buffer(p, 8, False);
+	generate_random_buffer(p, 8);
 
 	/* Our client code needs the the key in the clear, it does not
            know the server-key ... */
diff --git a/source3/lib/genrand.c b/source3/lib/genrand.c
index bc9f21c640..9ccddfa4c5 100644
--- a/source3/lib/genrand.c
+++ b/source3/lib/genrand.c
@@ -24,21 +24,32 @@
 
 static unsigned char hash[258];
 static uint32 counter;
-static unsigned char *reseed_data;
-static size_t reseed_data_size;
+
+static BOOL done_reseed = False;
+static void (*reseed_callback)(int *newseed);
 
 /**************************************************************** 
  Copy any user given reseed data.
 *****************************************************************/
 
-void set_rand_reseed_data(unsigned char *data, size_t len)
+void set_rand_reseed_callback(void (*fn)(int *))
 {
-	SAFE_FREE(reseed_data);
-	reseed_data_size = 0;
+	reseed_callback = fn;
+	set_need_random_reseed();
+}
 
-	reseed_data = (unsigned char *)memdup(data, len);
-	if (reseed_data)
-		reseed_data_size = len;
+void set_need_random_reseed(void)
+{
+	done_reseed = False;
+}
+
+static void get_rand_reseed_data(int *reseed_data)
+{
+	if (reseed_callback) {
+		reseed_callback(reseed_data);
+	} else {
+		*reseed_data = 0;
+	}
 }
 
 /**************************************************************** 
@@ -136,6 +147,7 @@ static int do_reseed(BOOL use_fd, int fd)
 	unsigned char seed_inbuf[40];
 	uint32 v1, v2; struct timeval tval; pid_t mypid;
 	struct passwd *pw;
+	int reseed_data = 0;
 
 	if (use_fd) {
 		if (fd != -1)
@@ -183,10 +195,11 @@ static int do_reseed(BOOL use_fd, int fd)
 	 * Add any user-given reseed data.
 	 */
 
+	get_rand_reseed_data(&reseed_data);
 	if (reseed_data) {
 		size_t i;
 		for (i = 0; i < sizeof(seed_inbuf); i++)
-			seed_inbuf[i] ^= reseed_data[i % reseed_data_size];
+			seed_inbuf[i] ^= ((char *)(&reseed_data))[i % sizeof(reseed_data)];
 	}
 
 	seed_random_stream(seed_inbuf, sizeof(seed_inbuf));
@@ -198,15 +211,14 @@ static int do_reseed(BOOL use_fd, int fd)
  Interface to the (hopefully) good crypto random number generator.
 ********************************************************************/
 
-void generate_random_buffer( unsigned char *out, int len, BOOL do_reseed_now)
+void generate_random_buffer( unsigned char *out, int len)
 {
-	static BOOL done_reseed = False;
 	static int urand_fd = -1;
 	unsigned char md4_buf[64];
 	unsigned char tmp_buf[16];
 	unsigned char *p;
 
-	if(!done_reseed || do_reseed_now) {
+	if(!done_reseed) {
 		urand_fd = do_reseed(True, urand_fd);
 		done_reseed = True;
 	}
@@ -257,7 +269,7 @@ char *generate_random_str(size_t len)
 
 	if (len > sizeof(retstr)-1)
 		len = sizeof(retstr) -1;
-	generate_random_buffer( retstr, len, False);
+	generate_random_buffer( retstr, len);
 	for (i = 0; i < len; i++)
 		retstr[i] = c_list[ retstr[i] % (sizeof(c_list)-1) ];
 
diff --git a/source3/lib/util_uuid.c b/source3/lib/util_uuid.c
index dc9bc92023..8f86c2109e 100644
--- a/source3/lib/util_uuid.c
+++ b/source3/lib/util_uuid.c
@@ -57,7 +57,7 @@ void smb_uuid_generate_random(struct uuid *uu)
 {
 	UUID_FLAT tmp;
 
-	generate_random_buffer(tmp.info, sizeof(tmp.info), True);
+	generate_random_buffer(tmp.info, sizeof(tmp.info));
 	smb_uuid_unpack(tmp, uu);
 
 	uu->clock_seq[0] = (uu->clock_seq[0] & 0x3F) | 0x80;
diff --git a/source3/libsmb/ntlmssp.c b/source3/libsmb/ntlmssp.c
index 66d48afc46..6e41a61bf1 100644
--- a/source3/libsmb/ntlmssp.c
+++ b/source3/libsmb/ntlmssp.c
@@ -103,7 +103,7 @@ void debug_ntlmssp_flags(uint32 neg_flags)
 static const uint8 *get_challenge(const struct ntlmssp_state *ntlmssp_state)
 {
 	static uchar chal[8];
-	generate_random_buffer(chal, sizeof(chal), False);
+	generate_random_buffer(chal, sizeof(chal));
 
 	return chal;
 }
@@ -960,7 +960,7 @@ static NTSTATUS ntlmssp_client_challenge(struct ntlmssp_state *ntlmssp_state,
 		E_md4hash(ntlmssp_state->password, nt_hash);
 		
 		lm_response = data_blob_talloc(ntlmssp_state->mem_ctx, NULL, 24);
-		generate_random_buffer(lm_response.data, 8, False);
+		generate_random_buffer(lm_response.data, 8);
 		memset(lm_response.data+8, 0, 16);
 
 		memcpy(session_nonce, challenge_blob.data, 8);
@@ -1022,7 +1022,7 @@ static NTSTATUS ntlmssp_client_challenge(struct ntlmssp_state *ntlmssp_state,
 	if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH) {
 		/* Make up a new session key */
 		uint8 client_session_key[16];
-		generate_random_buffer(client_session_key, sizeof(client_session_key), False);
+		generate_random_buffer(client_session_key, sizeof(client_session_key));
 
 		/* Encrypt the new session key with the old one */
 		encrypted_session_key = data_blob(client_session_key, sizeof(client_session_key));
diff --git a/source3/libsmb/smbencrypt.c b/source3/libsmb/smbencrypt.c
index 44f7428086..9f936b77ae 100644
--- a/source3/libsmb/smbencrypt.c
+++ b/source3/libsmb/smbencrypt.c
@@ -352,7 +352,7 @@ static DATA_BLOB NTLMv2_generate_client_data(const DATA_BLOB *names_blob)
 	DATA_BLOB response = data_blob(NULL, 0);
 	char long_date[8];
 
-	generate_random_buffer(client_chal, sizeof(client_chal), False);
+	generate_random_buffer(client_chal, sizeof(client_chal));
 
 	put_long_date(long_date, time(NULL));
 
@@ -406,7 +406,7 @@ static DATA_BLOB LMv2_generate_response(const uchar ntlm_v2_hash[16],
 	
 	/* LMv2 */
 	/* client-supplied random data */
-	generate_random_buffer(lmv2_client_data.data, lmv2_client_data.length, False);	
+	generate_random_buffer(lmv2_client_data.data, lmv2_client_data.length);	
 
 	/* Given that data, and the challenge from the server, generate a response */
 	SMBOWFencrypt_ntv2(ntlm_v2_hash, server_chal, &lmv2_client_data, lmv2_response);
@@ -476,7 +476,7 @@ BOOL encode_pw_buffer(char buffer[516], const char *password, int string_flags)
 	
 	memcpy(&buffer[512 - new_pw_len], new_pw, new_pw_len);
 
-	generate_random_buffer((unsigned char *)buffer, 512 - new_pw_len, True);
+	generate_random_buffer((unsigned char *)buffer, 512 - new_pw_len);
 
 	/* 
 	 * The length of the new password is in the last 4 bytes of
diff --git a/source3/nsswitch/wbinfo.c b/source3/nsswitch/wbinfo.c
index ce48e9ae65..b6a09bf2a1 100644
--- a/source3/nsswitch/wbinfo.c
+++ b/source3/nsswitch/wbinfo.c
@@ -580,7 +580,7 @@ static BOOL wbinfo_auth_crap(char *username)
 		return False;
 	}
 
-	generate_random_buffer(request.data.auth_crap.chal, 8, False);
+	generate_random_buffer(request.data.auth_crap.chal, 8);
         
         SMBencrypt(pass, request.data.auth_crap.chal, 
                    (uchar *)request.data.auth_crap.lm_resp);
diff --git a/source3/nsswitch/winbindd_pam.c b/source3/nsswitch/winbindd_pam.c
index 25f53e7a53..81d4e69ccd 100644
--- a/source3/nsswitch/winbindd_pam.c
+++ b/source3/nsswitch/winbindd_pam.c
@@ -190,7 +190,7 @@ enum winbindd_result winbindd_pam_auth(struct winbindd_cli_state *state)
 
 	/* do password magic */
 	
-	generate_random_buffer(chal, 8, False);
+	generate_random_buffer(chal, 8);
 	SMBencrypt(state->request.data.auth.pass, chal, local_lm_response);
 		
 	SMBNTencrypt(state->request.data.auth.pass, chal, local_nt_response);
diff --git a/source3/passdb/machine_sid.c b/source3/passdb/machine_sid.c
index 47b9e2d487..ce1354ce81 100644
--- a/source3/passdb/machine_sid.c
+++ b/source3/passdb/machine_sid.c
@@ -67,7 +67,7 @@ static void generate_random_sid(DOM_SID *sid)
 	sid->num_auths = 0;
 	sid->sub_auths[sid->num_auths++] = 21;
 
-	generate_random_buffer(raw_sid_data, 12, True);
+	generate_random_buffer(raw_sid_data, 12);
 	for (i = 0; i < 3; i++)
 		sid->sub_auths[sid->num_auths++] = IVAL(raw_sid_data, i*4);
 }
diff --git a/source3/passdb/secrets.c b/source3/passdb/secrets.c
index 2b3175bed2..e7637f689d 100644
--- a/source3/passdb/secrets.c
+++ b/source3/passdb/secrets.c
@@ -30,10 +30,27 @@
 
 static TDB_CONTEXT *tdb;
 
+/**
+ * Use a TDB to store an incrementing random seed.
+ *
+ * Initialised to the current pid, the very first time Samba starts,
+ * and incremented by one each time it is needed.  
+ * 
+ * @note Not called by systems with a working /dev/urandom.
+ */
+static void get_rand_seed(int *new_seed) 
+{
+	*new_seed = sys_getpid();
+	if (tdb) {
+		tdb_change_int32_atomic(tdb, "INFO/random_seed", new_seed, 1);
+	}
+}
+
 /* open up the secrets database */
 BOOL secrets_init(void)
 {
 	pstring fname;
+	char dummy;
 
 	if (tdb)
 		return True;
@@ -47,6 +64,18 @@ BOOL secrets_init(void)
 		DEBUG(0,("Failed to open %s\n", fname));
 		return False;
 	}
+
+	/**
+	 * Set a reseed function for the crypto random generator 
+	 * 
+	 * This avoids a problem where systems without /dev/urandom
+	 * could send the same challenge to multiple clients
+	 */
+	set_rand_reseed_callback(get_rand_seed);
+
+	/* Ensure that the reseed is done now, while we are root, etc */
+	generate_random_buffer(&dummy, sizeof(dummy));
+
 	return True;
 }
 
@@ -504,37 +533,6 @@ BOOL trusted_domain_password_delete(const char *domain)
 }
 
 
-/*******************************************************************
- Reset the 'done' variables so after a client process is created
- from a fork call these calls will be re-done. This should be
- expanded if more variables need reseting.
- ******************************************************************/
-
-void reset_globals_after_fork(void)
-{
-	unsigned char dummy;
-
-	secrets_init();
-
-	/*
-	 * Increment the global seed value to ensure every smbd starts
-	 * with a new random seed.
-	 */
-
-	if (tdb) {
-		uint32 initial_val = sys_getpid();
-		tdb_change_int32_atomic(tdb, "INFO/random_seed", (int *)&initial_val, 1);
-		set_rand_reseed_data((unsigned char *)&initial_val, sizeof(initial_val));
-	}
-
-	/*
-	 * Re-seed the random crypto generator, so all smbd's
-	 * started from the same parent won't generate the same
-	 * sequence.
-	 */
-	generate_random_buffer( &dummy, 1, True);
-}
-
 BOOL secrets_store_ldap_pw(const char* dn, char* pw)
 {
 	char *key = NULL;
diff --git a/source3/python/py_winbind.c b/source3/python/py_winbind.c
index 130f78d7e1..7256f77002 100644
--- a/source3/python/py_winbind.c
+++ b/source3/python/py_winbind.c
@@ -432,7 +432,7 @@ static PyObject *py_auth_crap(PyObject *self, PyObject *args, PyObject *kw)
 		return NULL;
 	}
 
-	generate_random_buffer(request.data.auth_crap.chal, 8, False);
+	generate_random_buffer(request.data.auth_crap.chal, 8);
         
 	if (use_lm_hash) {
 		SMBencrypt((uchar *)password, request.data.auth_crap.chal, 
@@ -481,7 +481,7 @@ static PyObject *py_auth_smbd(PyObject *self, PyObject *args, PyObject *kw)
 		return NULL;
 	}
 
-	generate_random_buffer(request.data.smbd_auth_crap.chal, 8, False);
+	generate_random_buffer(request.data.smbd_auth_crap.chal, 8);
         
 	if (use_lm_hash) {
 		SMBencrypt((uchar *)password, 
diff --git a/source3/rpc_client/cli_netlogon.c b/source3/rpc_client/cli_netlogon.c
index 02d2611d88..3fb032234f 100644
--- a/source3/rpc_client/cli_netlogon.c
+++ b/source3/rpc_client/cli_netlogon.c
@@ -247,7 +247,7 @@ NTSTATUS cli_nt_setup_creds(struct cli_state *cli,
 
         /******************* Request Challenge ********************/
 
-        generate_random_buffer(clnt_chal.data, 8, False);
+        generate_random_buffer(clnt_chal.data, 8);
 	
         /* send a client challenge; receive a server challenge */
         result = cli_net_req_chal(cli, &clnt_chal, &srv_chal);
@@ -580,7 +580,7 @@ NTSTATUS cli_netlogon_sam_logon(struct cli_state *cli, TALLOC_CTX *mem_ctx,
                 unsigned char local_lm_response[24];
                 unsigned char local_nt_response[24];
 
-                generate_random_buffer(chal, 8, False);
+                generate_random_buffer(chal, 8);
 
                 SMBencrypt(password, chal, local_lm_response);
                 SMBNTencrypt(password, chal, local_nt_response);
diff --git a/source3/rpc_parse/parse_prs.c b/source3/rpc_parse/parse_prs.c
index 92c5b13632..c70011c648 100644
--- a/source3/rpc_parse/parse_prs.c
+++ b/source3/rpc_parse/parse_prs.c
@@ -1471,7 +1471,7 @@ void netsec_encode(struct netsec_auth_struct *a, int auth_flags,
 	}
 
 	/* fill the 'confounder' with random data */
-	generate_random_buffer(confounder, sizeof(confounder), False);
+	generate_random_buffer(confounder, sizeof(confounder));
 
 	dump_data_pw("a->sess_key:\n", a->sess_key, sizeof(a->sess_key));
 
diff --git a/source3/rpc_server/srv_netlog_nt.c b/source3/rpc_server/srv_netlog_nt.c
index 264b7a74a7..b5871a7e56 100644
--- a/source3/rpc_server/srv_netlog_nt.c
+++ b/source3/rpc_server/srv_netlog_nt.c
@@ -276,7 +276,7 @@ NTSTATUS _net_req_chal(pipes_struct *p, NET_Q_REQ_CHAL *q_u, NET_R_REQ_CHAL *r_u
 
 	/* create a server challenge for the client */
 	/* Set these to random values. */
-	generate_random_buffer(p->dc.srv_chal.data, 8, False);
+	generate_random_buffer(p->dc.srv_chal.data, 8);
 	
 	memcpy(p->dc.srv_cred.challenge.data, p->dc.srv_chal.data, 8);
 
diff --git a/source3/rpc_server/srv_pipe.c b/source3/rpc_server/srv_pipe.c
index c5b0b5694d..bcf5eb533f 100644
--- a/source3/rpc_server/srv_pipe.c
+++ b/source3/rpc_server/srv_pipe.c
@@ -1097,7 +1097,7 @@ BOOL api_pipe_bind_req(pipes_struct *p, prs_struct *rpc_in_p)
 		RPC_AUTH_VERIFIER auth_verifier;
 		RPC_AUTH_NTLMSSP_CHAL ntlmssp_chal;
 
-		generate_random_buffer(p->challenge, 8, False);
+		generate_random_buffer(p->challenge, 8);
 
 		/*** Authentication info ***/
 
diff --git a/source3/smbd/server.c b/source3/smbd/server.c
index c3e0da542e..16281dd86c 100644
--- a/source3/smbd/server.c
+++ b/source3/smbd/server.c
@@ -409,11 +409,12 @@ static BOOL open_sockets_smbd(BOOL is_daemon, BOOL interactive, const char *smb_
 				   in smbstatus for port 445 connects */
 				set_remote_machine_name(get_peer_addr(smbd_server_fd()), False);
 				
-				/* Reset global variables in util.c so
-				   that client substitutions will be
-				   done correctly in the process.  */
-				reset_globals_after_fork();
+				/* Reset the state of the random
+				 * number generation system, so
+				 * children do not get the same random
+				 * numbers as each other */
 
+				set_need_random_reseed();
 				/* tdb needs special fork handling - remove CLEAR_IF_FIRST flags */
 				if (tdb_reopen_all() == -1) {
 					DEBUG(0,("tdb_reopen_all failed.\n"));
@@ -717,7 +718,7 @@ void build_options(BOOL screen);
 
 	/* we want to re-seed early to prevent time delays causing
            client problems at a later date. (tridge) */
-	generate_random_buffer(NULL, 0, False);
+	generate_random_buffer(NULL, 0);
 
 	/* make absolutely sure we run as root - to handle cases where people
 	   are crazy enough to have it setuid */
diff --git a/source3/torture/torture.c b/source3/torture/torture.c
index e3960d3406..6c3860e233 100644
--- a/source3/torture/torture.c
+++ b/source3/torture/torture.c
@@ -493,7 +493,7 @@ static BOOL rw_torture2(struct cli_state *c1, struct cli_state *c2)
 			printf("%d\r", i); fflush(stdout);
 		}
 
-		generate_random_buffer(buf, buf_size, False);
+		generate_random_buffer(buf, buf_size);
 
 		if (cli_write(c1, fnum1, 0, buf, 0, buf_size) != buf_size) {
 			printf("write failed (%s)\n", cli_errstr(c1));
diff --git a/source3/utils/ntlm_auth.c b/source3/utils/ntlm_auth.c
index 39dcd9993d..fd8424065c 100644
--- a/source3/utils/ntlm_auth.c
+++ b/source3/utils/ntlm_auth.c
@@ -181,7 +181,7 @@ DATA_BLOB get_challenge(void)
 	
 	chal = data_blob(NULL, 8);
 
-	generate_random_buffer(chal.data, chal.length, False);
+	generate_random_buffer(chal.data, chal.length);
 	return chal;
 }
 
diff --git a/source3/wrepld/server.c b/source3/wrepld/server.c
index 80694a616b..d78e0b206f 100644
--- a/source3/wrepld/server.c
+++ b/source3/wrepld/server.c
@@ -551,7 +551,7 @@ static void process(void)
 
 	/* we want to re-seed early to prevent time delays causing
            client problems at a later date. (tridge) */
-	generate_random_buffer(NULL, 0, False);
+	generate_random_buffer(NULL, 0);
 
 	/* make absolutely sure we run as root - to handle cases where people
 	   are crazy enough to have it setuid */