com php-src: Add support for getrandom(2), add type check on file descriptor: ext/standard/config.m4 ext/standard/random.c
ext/standard/tests/random/random_bytes.phpt

Commit: 6554f721f770c99037f07d465a7d610568576ce4 Author: Scott <scott@paragonie.com> Wed, 9 Sep 2015 06:50:06 -0400 Committer: Anatol Belski <ab@php.net> Tue, 29 Sep 2015 09:14:28 +0200 Parents: 208ed0a01059a32af38be5c3c5481c200c8ec4a2 Branches: PHP-7.0 master Link: http://git.php.net/?p=php-src.git;a=commitdiff;h=6554f721f770c99037f07d465a7d610568576ce4 Log: Add support for getrandom(2), add type check on file descriptor Fix to_read, throw exception if syscall fails Fixes thanks to feedback from sarnold at ##crypto on freenode Correction on error conditions Remove dead code (thanks @defuse) It turns out getrandom can take >256, getentropy refuses. Better semantics Thanks @defuse for catching my silly mistake here Cast to size_t to be explicit Let's simplify the logic a bit Let's be consistent; define everything before we do any logic Continuously check that the file descriptor is still a valid one Add device type check on fd initialization Changed paths: M ext/standard/config.m4 M ext/standard/random.c M ext/standard/tests/random/random_bytes.phpt Diff: diff --git a/ext/standard/config.m4 b/ext/standard/config.m4 index c75b141..c435f96 100644 --- a/ext/standard/config.m4 +++ b/ext/standard/config.m4 @@ -598,6 +598,11 @@ dnl AC_CHECK_DECLS([arc4random_buf]) dnl +dnl Check for getrandom on newer Linux kernels +dnl +AC_CHECK_DECLS([getrandom]) + +dnl dnl Setup extension sources dnl PHP_NEW_EXTENSION(standard, array.c base64.c basic_functions.c browscap.c crc32.c crypt.c \ diff --git a/ext/standard/random.c b/ext/standard/random.c index e2e4895..6bee9d3 100644 --- a/ext/standard/random.c +++ b/ext/standard/random.c @@ -30,6 +30,9 @@ #if PHP_WIN32 # include "win32/winutil.h" #endif +#ifdef __linux__ +# include <linux/random.h> +#endif #ifdef ZTS int random_globals_id; @@ -75,6 +78,7 @@ PHP_MSHUTDOWN_FUNCTION(random) /* }}} */ /* {{{ */ + static int php_random_bytes(void *bytes, size_t size) { #if PHP_WIN32 @@ -85,26 +89,75 @@ static int php_random_bytes(void *bytes, size_t size) } #elif HAVE_DECL_ARC4RANDOM_BUF arc4random_buf(bytes, size); +#elif HAVE_DECL_GETRANDOM + /* Linux getrandom(2) syscall */ + size_t read_bytes = 0; + size_t amount_to_read = 0; + ssize_t n; + + /* Keep reading until we get enough entropy */ + do { + amount_to_read = size - read_bytes; + /* Below, (bytes + read_bytes) is pointer arithmetic. + + bytes read_bytes size + | | | + [#######=============] (we're going to write over the = region) + \\\\\\\\\\\\\ + amount_to_read + + */ + n = getrandom(bytes + read_bytes, amount_to_read, 0); + + if (n == -1) { + if (errno == EINTR || errno == EAGAIN) { + /* Try again */ + continue; + } + /* + If the syscall fails, we are doomed. The loop that calls + php_random_bytes should be terminated by the exception instead + of proceeding to demand more entropy. + */ + zend_throw_exception(zend_ce_exception, "Could not gather sufficient random data", errno); + return FAILURE; + } + + read_bytes += (size_t) n; + } while (read_bytes < size); #else int fd = RANDOM_G(fd); + struct stat st; size_t read_bytes = 0; + ssize_t n; if (fd < 0) { -#if HAVE_DEV_ARANDOM - fd = open("/dev/arandom", O_RDONLY); -#elif HAVE_DEV_URANDOM +#if HAVE_DEV_URANDOM fd = open("/dev/urandom", O_RDONLY); #endif if (fd < 0) { zend_throw_exception(zend_ce_exception, "Cannot open source device", 0); return FAILURE; } - + /* Does the file exist and is it a character device? */ + if (fstat(fd, &st) != 0 || !S_ISCHR(st.st_mode)) { + close(fd); + zend_throw_exception(zend_ce_exception, "Error reading from source device", 0); + return FAILURE; + } +#ifdef __linux__ + // Make sure that /dev/urandom is the proper urandom device on Linux + if (st.st_rdev != makedev(1, 9)) { + close(fd); + zend_throw_exception(zend_ce_exception, "Error reading from source device", 0); + return FAILURE; + } +#endif RANDOM_G(fd) = fd; } while (read_bytes < size) { - ssize_t n = read(fd, bytes + read_bytes, size - read_bytes); + n = read(fd, bytes + read_bytes, size - read_bytes); if (n <= 0) { break; } diff --git a/ext/standard/tests/random/random_bytes.phpt b/ext/standard/tests/random/random_bytes.phpt index 8639138..6a7d438 100644 --- a/ext/standard/tests/random/random_bytes.phpt +++ b/ext/standard/tests/random/random_bytes.phpt @@ -8,7 +8,10 @@ var_dump(strlen(bin2hex(random_bytes(16)))); var_dump(is_string(random_bytes(10))); +var_dump(is_string(random_bytes(257))); + ?> --EXPECT-- int(32) bool(true) +bool(true)