diff options
Diffstat (limited to 'compat/arc4random.c')
| -rw-r--r-- | compat/arc4random.c | 73 |
1 files changed, 71 insertions, 2 deletions
diff --git a/compat/arc4random.c b/compat/arc4random.c index a09665c5df22..bcef0ec90f8a 100644 --- a/compat/arc4random.c +++ b/compat/arc4random.c @@ -71,6 +71,72 @@ static struct { static inline void _rs_rekey(u_char *dat, size_t datlen); +/* + * Basic sanity checking; wish we could do better. + */ +static int +fallback_gotdata(char *buf, size_t len) +{ + char any_set = 0; + size_t i; + + for (i = 0; i < len; ++i) + any_set |= buf[i]; + if (any_set == 0) + return -1; + return 0; +} + +/* fallback for getentropy in case libc returns failure */ +static int +fallback_getentropy_urandom(void *buf, size_t len) +{ + size_t i; + int fd, flags; + int save_errno = errno; + +start: + + flags = O_RDONLY; +#ifdef O_NOFOLLOW + flags |= O_NOFOLLOW; +#endif +#ifdef O_CLOEXEC + flags |= O_CLOEXEC; +#endif + fd = open("/dev/urandom", flags, 0); + if (fd == -1) { + if (errno == EINTR) + goto start; + goto nodevrandom; + } +#ifndef O_CLOEXEC +# ifdef HAVE_FCNTL + fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC); +# endif +#endif + for (i = 0; i < len; ) { + size_t wanted = len - i; + ssize_t ret = read(fd, (char*)buf + i, wanted); + + if (ret == -1) { + if (errno == EAGAIN || errno == EINTR) + continue; + close(fd); + goto nodevrandom; + } + i += ret; + } + close(fd); + if (fallback_gotdata(buf, len) == 0) { + errno = save_errno; + return 0; /* satisfied */ + } +nodevrandom: + errno = EIO; + return -1; +} + static inline void _rs_init(u_char *buf, size_t n) { @@ -114,11 +180,14 @@ _rs_stir(void) u_char rnd[KEYSZ + IVSZ]; if (getentropy(rnd, sizeof rnd) == -1) { + if(errno != ENOSYS || + fallback_getentropy_urandom(rnd, sizeof rnd) == -1) { #ifdef SIGKILL - raise(SIGKILL); + raise(SIGKILL); #else - exit(9); /* windows */ + exit(9); /* windows */ #endif + } } if (!rs) |