X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/48c99b2c840180331f14e9ad6d1a13dcdac411ff..264dce47a146f5c16d1fce4b99a0bb0f9e5eb093:/entropy.c

diff --git a/entropy.c b/entropy.c
index cecf9e8d..84b1dd1d 100644
--- a/entropy.c
+++ b/entropy.c
@@ -55,68 +55,94 @@ RCSID("$Id$");
 
 #define WHITESPACE " \t\n"
 
+#ifndef RUSAGE_SELF
+# define RUSAGE_SELF 0
+#endif
+#ifndef RUSAGE_CHILDREN
+# define RUSAGE_CHILDREN 0
+#endif
+
 #if defined(EGD_SOCKET) || defined(RANDOM_POOL)
 
 #ifdef EGD_SOCKET
 /* Collect entropy from EGD */
-void get_random_bytes(unsigned char *buf, int len)
+int get_random_bytes(unsigned char *buf, int len)
 {
-	static int egd_socket = -1;
-	int c;
-	char egd_message[2] = { 0x02, 0x00 };
+	int fd;
+	char msg[2];
 	struct sockaddr_un addr;
 	int addr_len;
 
-	memset(&addr, '\0', sizeof(addr));
-	addr.sun_family = AF_UNIX;
-	
-	/* FIXME: compile time check? */
+	/* Sanity checks */
 	if (sizeof(EGD_SOCKET) > sizeof(addr.sun_path))
 		fatal("Random pool path is too long");
-	
+	if (len > 255)
+		fatal("Too many bytes to read from EGD");
+
+	memset(&addr, '\0', sizeof(addr));
+	addr.sun_family = AF_UNIX;
 	strlcpy(addr.sun_path, EGD_SOCKET, sizeof(addr.sun_path));
-	
 	addr_len = offsetof(struct sockaddr_un, sun_path) + sizeof(EGD_SOCKET);
 	
-	if (egd_socket == -1) {
-		egd_socket = socket(AF_UNIX, SOCK_STREAM, 0);
-		if (egd_socket == -1)
-			fatal("Couldn't create AF_UNIX socket: %s", strerror(errno));
-		if (connect(egd_socket, (struct sockaddr*)&addr, addr_len) == -1)
-			fatal("Couldn't connect to EGD socket \"%s\": %s", addr.sun_path, strerror(errno));
-	}	
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd == -1) {
+		error("Couldn't create AF_UNIX socket: %s", strerror(errno));
+		return(0);
+	}
+
+	if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
+		error("Couldn't connect to EGD socket \"%s\": %s", 
+			addr.sun_path, strerror(errno));
+		close(fd);
+		return(0);
+	}
 
-	if (len > 255)
-		fatal("Too many bytes to read from EGD");
-	
 	/* Send blocking read request to EGD */
-	egd_message[1] = len;
+	msg[0] = 0x02;
+	msg[1] = len;
 
-	c = atomicio(write, egd_socket, egd_message, sizeof(egd_message));
-	if (c == -1)
-		fatal("Couldn't write to EGD socket \"%s\": %s", EGD_SOCKET, strerror(errno));
+	if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) {
+		error("Couldn't write to EGD socket \"%s\": %s", 
+			EGD_SOCKET, strerror(errno));
+		close(fd);
+		return(0);
+	}
 
-	c = atomicio(read, egd_socket, buf, len);
-	if (c <= 0)
-		fatal("Couldn't read from EGD socket \"%s\": %s", EGD_SOCKET, strerror(errno));
+	if (atomicio(read, fd, buf, len) != len) {
+		error("Couldn't read from EGD socket \"%s\": %s", 
+			EGD_SOCKET, strerror(errno));
+		close(fd);
+		return(0);
+	}
+	
+	close(fd);
+	
+	return(1);
 }
 #else /* !EGD_SOCKET */
 #ifdef RANDOM_POOL
 /* Collect entropy from /dev/urandom or pipe */
-void get_random_bytes(unsigned char *buf, int len)
+int get_random_bytes(unsigned char *buf, int len)
 {
-	static int random_pool = -1;
-	int c;
+	int random_pool;
 
+	random_pool = open(RANDOM_POOL, O_RDONLY);
 	if (random_pool == -1) {
-		random_pool = open(RANDOM_POOL, O_RDONLY);
-		if (random_pool == -1)
-			fatal("Couldn't open random pool \"%s\": %s", RANDOM_POOL, strerror(errno));
+		error("Couldn't open random pool \"%s\": %s", 
+			RANDOM_POOL, strerror(errno));
+		return(0);
 	}
 	
-	c = atomicio(read, random_pool, buf, len);
-	if (c <= 0)
-		fatal("Couldn't read from random pool \"%s\": %s", RANDOM_POOL, strerror(errno));
+	if (atomicio(read, random_pool, buf, len) != len) {
+		error("Couldn't read from random pool \"%s\": %s", 
+			RANDOM_POOL, strerror(errno));
+		close(random_pool);
+		return(0);
+	}
+	
+	close(random_pool);
+	
+	return(1);
 }
 #endif /* RANDOM_POOL */
 #endif /* EGD_SOCKET */
@@ -131,11 +157,20 @@ seed_rng(void)
 	char buf[32];
 	
 	debug("Seeding random number generator");
-	get_random_bytes(buf, sizeof(buf));
-	RAND_add(buf, sizeof(buf), sizeof(buf));
+
+	if (!get_random_bytes(buf, sizeof(buf))) {
+		if (!RAND_status())
+			fatal("Entropy collection failed and entropy exhausted");
+	} else {
+		RAND_add(buf, sizeof(buf), sizeof(buf));
+	}
+	
 	memset(buf, '\0', sizeof(buf));
 }
 
+/* No-op */
+void init_rng(void) {}
+
 #else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */
 
 /* 
@@ -148,9 +183,9 @@ seed_rng(void)
 /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
 static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
 
-static int prng_seed_loaded = 0;
 static int prng_seed_saved = 0;
-static int prng_commands_loaded = 0;
+static int prng_initialised = 0;
+uid_t original_uid;
 
 typedef struct
 {
@@ -187,11 +222,11 @@ stir_from_system(void)
 	total_entropy_estimate = 0;
 	
 	i = getpid();
-	RAND_add(&i, sizeof(i), 0.1);
+	RAND_add(&i, sizeof(i), 0.5);
 	total_entropy_estimate += 0.1;
 	
 	i = getppid();
-	RAND_add(&i, sizeof(i), 0.1);
+	RAND_add(&i, sizeof(i), 0.5);
 	total_entropy_estimate += 0.1;
 
 	i = getuid();
@@ -200,7 +235,7 @@ stir_from_system(void)
 	RAND_add(&i, sizeof(i), 0.0);
 
 	total_entropy_estimate += stir_gettimeofday(1.0);
-	total_entropy_estimate += stir_clock(0.2);
+	total_entropy_estimate += stir_clock(0.5);
 	total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
 
 	return(total_entropy_estimate);
@@ -301,9 +336,9 @@ stir_rusage(int who, double entropy_estimate)
 	struct rusage ru;
 	
 	if (getrusage(who, &ru) == -1)
-		fatal("Couldn't getrusage: %s", strerror(errno));
+		return(0);
 
-	RAND_add(&ru, sizeof(ru), 0.1);
+	RAND_add(&ru, sizeof(ru), entropy_estimate);
 
 	return(entropy_estimate);
 #else /* _HAVE_GETRUSAGE */
@@ -363,10 +398,10 @@ hash_output_from_command(entropy_source_t *src, char *hash)
 			close(p[1]);
 			close(devnull);
 
+			setuid(original_uid);
 			execv(src->path, (char**)(src->args));
 			debug("(child) Couldn't exec '%s': %s", src->cmdstring,
 			      strerror(errno));
-			src->badness = src->sticky_badness = 128;
 			_exit(-1);
 		default: /* Parent */
 			break;
@@ -400,38 +435,36 @@ hash_output_from_command(entropy_source_t *src, char *hash)
 
 		ret = select(p[0]+1, &rdset, NULL, NULL, &tv);
 
+		RAND_add(&tv, sizeof(tv), 0.0);
+
 		switch (ret) {
 		case 0:
 			/* timer expired */
 			error_abort = 1;
 			break;
-			
 		case 1:
 			/* command input */
 			bytes_read = read(p[0], buf, sizeof(buf));
+			RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
 			if (bytes_read == -1) {
 				error_abort = 1;
 				break;
-			}
-			if (bytes_read) {
+			} else if (bytes_read) {
 				SHA1_Update(&sha, buf, bytes_read);
 				total_bytes_read += bytes_read;
-				RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
-			} else
+			} else {
 				cmd_eof = 1;
-
+			}
 			break;
-
 		case -1:
 		default:
+			/* error */
 			debug("Command '%s': select() failed: %s", src->cmdstring,
 			      strerror(errno));
 			error_abort = 1;
 			break;
-		} /* switch ret */
-
-		RAND_add(&tv, sizeof(&tv), 0.0);
-	} /* while !error_abort && !cmd_eof */
+		}
+	}
 
 	SHA1_Final(hash, &sha);
 
@@ -501,7 +534,7 @@ prng_check_seedfile(char *filename) {
 		fatal("PRNG seedfile %.100s is not a regular file", filename);
 
 	/* mode 0600, owned by root or the current user? */
-	if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid()))
+	if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid))
 		fatal("PRNG seedfile %.100s must be mode 0600, owned by uid %d",
 			 filename, getuid());
 
@@ -519,12 +552,14 @@ prng_write_seedfile(void) {
 	if (prng_seed_saved)
 		return;
 	
+	setuid(original_uid);
+	
 	prng_seed_saved = 1;
 	
-	pw = getpwuid(getuid());
+	pw = getpwuid(original_uid);
 	if (pw == NULL)
 		fatal("Couldn't get password entry for current user (%i): %s", 
-			getuid(), strerror(errno));
+			original_uid, strerror(errno));
 				
 	/* Try to ensure that the parent directory is there */
 	snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
@@ -559,10 +594,10 @@ prng_read_seedfile(void) {
 	char filename[1024];
 	struct passwd *pw;
 	
-	pw = getpwuid(getuid());
+	pw = getpwuid(original_uid);
 	if (pw == NULL)
 		fatal("Couldn't get password entry for current user (%i): %s", 
-			getuid(), strerror(errno));
+			original_uid, strerror(errno));
 			
 	snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
 		SSH_PRNG_SEED_FILE);
@@ -723,7 +758,7 @@ prng_read_commands(char *cmdfilename)
 	/* trim to size */
 	entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t));
 
-	debug("loaded %d entropy commands from %.100s", cur_cmd, cmdfilename);
+	debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename);
 
 	return (cur_cmd >= MIN_ENTROPY_SOURCES);
 }
@@ -745,35 +780,41 @@ void
 seed_rng(void)
 {
 	void *old_sigchld_handler;
-	
-	if (!prng_commands_loaded) {
-		if (!prng_read_commands(SSH_PRNG_COMMAND_FILE))
-			fatal("PRNG initialisation failed -- exiting.");
-		prng_commands_loaded = 1;
-	}
 
+	if (!prng_initialised)
+		fatal("RNG not initialised");
+	
 	/* Make sure some other sigchld handler doesn't reap our entropy */
 	/* commands */
 	old_sigchld_handler = signal(SIGCHLD, SIG_DFL);
 
-	debug("Seeding random number generator.");
-	debug("OpenSSL random status is now %i\n", RAND_status());
-	debug("%i bytes from system calls", (int)stir_from_system());
-	debug("%i bytes from programs", (int)stir_from_programs());
-	debug("OpenSSL random status is now %i\n", RAND_status());
+	debug("Seeded RNG with %i bytes from programs", (int)stir_from_programs());
+	debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system());
+
+	if (!RAND_status())
+		fatal("Not enough entropy in RNG");
 
 	signal(SIGCHLD, old_sigchld_handler);
 
 	if (!RAND_status())
 		fatal("Couldn't initialise builtin random number generator -- exiting.");
+}
 
-	if (!prng_seed_loaded)
-	{
-		prng_seed_loaded = 1;
-		prng_seed_saved = 0;		
-		prng_read_seedfile();
-		fatal_add_cleanup(prng_seed_cleanup, NULL);
-		atexit(prng_write_seedfile);
-	}
+void init_rng(void) 
+{
+	original_uid = getuid();
+
+	/* Read in collection commands */
+	if (!prng_read_commands(SSH_PRNG_COMMAND_FILE))
+		fatal("PRNG initialisation failed -- exiting.");
+
+	/* Set ourselves up to save a seed upon exit */
+	prng_seed_saved = 0;		
+	prng_read_seedfile();
+	fatal_add_cleanup(prng_seed_cleanup, NULL);
+	atexit(prng_write_seedfile);
+
+	prng_initialised = 1;
 }
+
 #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */