Merge branch 'oneshot-urandom' into 'master'

sysrng-linux: re-open /dev/urandom every time

Closes #1188

See merge request gnutls/gnutls!1396

9 files changed, 24 insertions, 81 deletions

diff --git a/lib/global.c b/lib/global.c
index 9a65d114cc..b41e20a9a0 100644
--- a/lib/global.c
+++ b/lib/global.c
@@ -236,16 +236,6 @@ static int _gnutls_global_init(unsigned constructor)
 
 	_gnutls_init++;
 	if (_gnutls_init > 1) {
-		if (_gnutls_init == 2 && _gnutls_init_ret == 0) {
-			/* some applications may close the urandom fd 
-			 * before calling gnutls_global_init(). in that
-			 * case reopen it */
-			ret = _gnutls_rnd_check();
-			if (ret < 0) {
-				gnutls_assert();
-				goto out;
-			}
-		}
 		ret = _gnutls_init_ret;
 		goto out;
 	}
diff --git a/lib/nettle/rnd-common.h b/lib/nettle/rnd-common.h
index 429ca017d3..025fe02e8f 100644
--- a/lib/nettle/rnd-common.h
+++ b/lib/nettle/rnd-common.h
@@ -35,7 +35,6 @@
 #include <fips.h>
 
 int _rnd_system_entropy_init(void);
-int _rnd_system_entropy_check(void);
 void _rnd_system_entropy_deinit(void);
 
 typedef int (*get_entropy_func)(void* rnd, size_t size);
diff --git a/lib/nettle/sysrng-bcrypt.c b/lib/nettle/sysrng-bcrypt.c
index 10dc9ac83a..a08e9deb92 100644
--- a/lib/nettle/sysrng-bcrypt.c
+++ b/lib/nettle/sysrng-bcrypt.c
@@ -64,11 +64,6 @@ int _rnd_get_system_entropy_win32(void* rnd, size_t size)
 	return 0;
 }
 
-int _rnd_system_entropy_check(void)
-{
-	return 0;
-}
-
 int _rnd_system_entropy_init(void)
 {
 	NTSTATUS err = BCryptOpenAlgorithmProvider
diff --git a/lib/nettle/sysrng-getentropy.c b/lib/nettle/sysrng-getentropy.c
index 99e95ead8b..0666d482c2 100644
--- a/lib/nettle/sysrng-getentropy.c
+++ b/lib/nettle/sysrng-getentropy.c
@@ -71,11 +71,6 @@ int _rnd_system_entropy_init(void)
 	return 0;
 }
 
-int _rnd_system_entropy_check(void)
-{
-	return 0;
-}
-
 void _rnd_system_entropy_deinit(void)
 {
 	return;
diff --git a/lib/nettle/sysrng-linux.c b/lib/nettle/sysrng-linux.c
index 2e17ecdd0c..6b3971c65f 100644
--- a/lib/nettle/sysrng-linux.c
+++ b/lib/nettle/sysrng-linux.c
@@ -46,10 +46,6 @@
 #include <sys/time.h>
 #include <fcntl.h>
 
-static int _gnutls_urandom_fd = -1;
-static ino_t _gnutls_urandom_fd_ino = 0;
-static dev_t _gnutls_urandom_fd_rdev = 0;
-
 get_entropy_func _rnd_get_system_entropy = NULL;
 
 #if defined(__linux__)
@@ -127,11 +123,18 @@ static int _rnd_get_system_entropy_urandom(void* _rnd, size_t size)
 {
 	uint8_t* rnd = _rnd;
 	uint32_t done;
+	int urandom_fd;
+
+	urandom_fd = open("/dev/urandom", O_RDONLY);
+	if (urandom_fd < 0) {
+		_gnutls_debug_log("Cannot open /dev/urandom!\n");
+		return GNUTLS_E_RANDOM_DEVICE_ERROR;
+	}
 
 	for (done = 0; done < size;) {
 		int res;
 		do {
-			res = read(_gnutls_urandom_fd, rnd + done, size - done);
+			res = read(urandom_fd, rnd + done, size - done);
 		} while (res < 0 && errno == EINTR);
 
 		if (res <= 0) {
@@ -145,74 +148,51 @@ static int _rnd_get_system_entropy_urandom(void* _rnd, size_t size)
 					("Failed to read /dev/urandom: end of file\n");
 			}
 
+			close(urandom_fd);
 			return GNUTLS_E_RANDOM_DEVICE_ERROR;
 		}
 
 		done += res;
 	}
 
-	return 0;
-}
-
-/* This is called when gnutls_global_init() is called for second time.
- * It must check whether any resources are still available.
- * The particular problem it solves is to verify that the urandom fd is still
- * open (for applications that for some reason closed all fds */
-int _rnd_system_entropy_check(void)
-{
-	int ret;
-	struct stat st;
-
-	if (_gnutls_urandom_fd == -1) /* not using urandom */
-		return 0;
-
-	ret = fstat(_gnutls_urandom_fd, &st);
-	if (ret < 0 || st.st_ino != _gnutls_urandom_fd_ino || st.st_rdev != _gnutls_urandom_fd_rdev) {
-		return _rnd_system_entropy_init();
-	}
+	close(urandom_fd);
 	return 0;
 }
 
 int _rnd_system_entropy_init(void)
 {
-	int old;
-	struct stat st;
+	int urandom_fd;
 
 #if defined(__linux__)
 	/* Enable getrandom() usage if available */
 	if (have_getrandom()) {
 		_rnd_get_system_entropy = _rnd_get_system_entropy_getrandom;
-		_gnutls_debug_log("getrandom random generator was detected\n");
+		_gnutls_debug_log("getrandom random generator was selected\n");
 		return 0;
+	} else {
+		_gnutls_debug_log("getrandom is not available\n");
 	}
 #endif
 
-	/* First fallback: /dev/unrandom */
-	_gnutls_urandom_fd = open("/dev/urandom", O_RDONLY);
-	if (_gnutls_urandom_fd < 0) {
-		_gnutls_debug_log("Cannot open urandom!\n");
-		return gnutls_assert_val(GNUTLS_E_RANDOM_DEVICE_ERROR);
-	}
-
-	old = fcntl(_gnutls_urandom_fd, F_GETFD);
-	if (old != -1)
-		fcntl(_gnutls_urandom_fd, F_SETFD, old | FD_CLOEXEC);
+	/* Fallback: /dev/urandom */
 
-	if (fstat(_gnutls_urandom_fd, &st) >= 0) {
-		_gnutls_urandom_fd_ino = st.st_ino;
-		_gnutls_urandom_fd_rdev = st.st_rdev;
+	/* Check that we can open it */
+	urandom_fd = open("/dev/urandom", O_RDONLY);
+	if (urandom_fd < 0) {
+		_gnutls_debug_log("Cannot open /dev/urandom during initialization!\n");
+		return gnutls_assert_val(GNUTLS_E_RANDOM_DEVICE_ERROR);
 	}
+	close(urandom_fd);
 
 	_rnd_get_system_entropy = _rnd_get_system_entropy_urandom;
+	_gnutls_debug_log("/dev/urandom random generator was selected\n");
 
 	return 0;
 }
 
 void _rnd_system_entropy_deinit(void)
 {
-	if (_gnutls_urandom_fd >= 0) {
-		close(_gnutls_urandom_fd);
-		_gnutls_urandom_fd = -1;
-	}
+	/* A no-op now when we open and close /dev/urandom every time */
+	return;
 }
 
diff --git a/lib/nettle/sysrng-netbsd.c b/lib/nettle/sysrng-netbsd.c
index 7fb3d8d326..7f74b4eed4 100644
--- a/lib/nettle/sysrng-netbsd.c
+++ b/lib/nettle/sysrng-netbsd.c
@@ -71,11 +71,6 @@ int _rnd_system_entropy_init(void)
 	return 0;
 }
 
-int _rnd_system_entropy_check(void)
-{
-	return 0;
-}
-
 void _rnd_system_entropy_deinit(void)
 {
 	return;
diff --git a/lib/nettle/sysrng-windows.c b/lib/nettle/sysrng-windows.c
index 9d38e67ec1..8c931d29cc 100644
--- a/lib/nettle/sysrng-windows.c
+++ b/lib/nettle/sysrng-windows.c
@@ -64,11 +64,6 @@ int _rnd_get_system_entropy_win32(void* rnd, size_t size)
 	return 0;
 }
 
-int _rnd_system_entropy_check(void)
-{
-	return 0;
-}
-
 int _rnd_system_entropy_init(void)
 {
 	if (!CryptAcquireContext
diff --git a/lib/random.h b/lib/random.h
index 62b4dc2a07..0d76738971 100644
--- a/lib/random.h
+++ b/lib/random.h
@@ -33,9 +33,4 @@ extern gnutls_crypto_rnd_st _gnutls_rnd_ops;
 void _gnutls_rnd_deinit(void);
 int _gnutls_rnd_preinit(void);
 
-inline static int _gnutls_rnd_check(void)
-{
-	return _rnd_system_entropy_check();
-}
-
 #endif /* GNUTLS_LIB_RANDOM_H */
diff --git a/tests/rng-sigint.c b/tests/rng-sigint.c
index 76b76f353c..04e818ede9 100644
--- a/tests/rng-sigint.c
+++ b/tests/rng-sigint.c
@@ -44,7 +44,6 @@
 #define gnutls_assert_val(val) val
 
 int _rnd_system_entropy_init(void);
-int _rnd_system_entropy_check(void);
 void _rnd_system_entropy_deinit(void);
 
 typedef int (*get_entropy_func)(void* rnd, size_t size);