diff options
Diffstat (limited to 'stdlib/tst-getrandom.c')
| -rw-r--r-- | stdlib/tst-getrandom.c | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/stdlib/tst-getrandom.c b/stdlib/tst-getrandom.c new file mode 100644 index 0000000000..a76cd1868b --- /dev/null +++ b/stdlib/tst-getrandom.c @@ -0,0 +1,245 @@ +/* Tests for the getentropy, getrandom functions. + Copyright (C) 2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <errno.h> +#include <stdbool.h> +#include <stdio.h> +#include <string.h> +#include <sys/random.h> + +/* Set to true if any errors are encountered. */ +static bool errors; + +/* Test getrandom with a single buffer length. NB: The passed-in + buffer must have room for four extra bytes after the specified + length, which are used to test that getrandom leaves those bytes + unchanged. */ +static void +test_length (char *buffer, size_t length, unsigned int flags) +{ + memset (buffer, 0, length); + strcpy (buffer + length, "123"); + ssize_t ret = getrandom (buffer, length, flags); + if (ret < 0) + { + /* EAGAIN is an expected error with GRND_RANDOM and + GRND_NONBLOCK. */ + if ((flags & GRND_RANDOM) + && (flags & GRND_NONBLOCK) + && errno == EAGAIN) + return; + printf ("error: getrandom (%zu, 0x%x): %m\n", length, flags); + errors = true; + return; + } + if (ret != length) + { + if (flags & GRND_RANDOM) + { + if (ret == 0 || ret > length) + { + printf ("error: getrandom (%zu, 0x%x) returned %zd\n", + length, flags, ret); + errors = true; + } + } + else + { + printf ("error: getrandom (%zu, 0x%x) returned %zd\n", + length, flags, ret); + errors = true; + } + } + if (length >= 7) + { + /* One spurious test failure in 2**56 is sufficiently + unlikely. */ + int non_null = 0; + for (int i = 0; i < length; ++i) + non_null += buffer[i] != 0; + if (non_null == 0) + { + printf ("error: getrandom (%zu, 0x%x) returned all-zero bytes\n", + length, flags); + errors = true; + } + } + if (memcmp (buffer + length, "123", 4) != 0) + { + printf ("error: getrandom (%zu, 0x%x) wrote spurious bytes\n", + length, flags); + errors = true; + } +} + +/* Call getrandom repeatedly to fill the buffer. */ +static bool +getrandom_full (char *buffer, size_t length, unsigned int flags) +{ + char *end = buffer + length; + while (buffer < end) + { + ssize_t ret = getrandom (buffer, end - buffer, flags); + if (ret < 0) + { + printf ("error: getrandom (%zu, 0x%x): %m\n", length, flags); + errors = true; + return false; + } + buffer += ret; + } + + return true; +} + +static void +test_flags (unsigned int flags) +{ + /* Test various lengths, but only for !GRND_RANDOM, to conserve + entropy. */ + { + enum { max_length = 300 }; + char buffer[max_length + 4]; + if (flags & GRND_RANDOM) + test_length (buffer, 0, flags); + else + { + for (int length = 0; length <= 9; ++length) + test_length (buffer, length, flags); + test_length (buffer, 16, flags); + test_length (buffer, max_length, flags); + } + } + + /* Test that getrandom returns different data. */ + if (!(flags & GRND_NONBLOCK)) + { + char buffer1[8]; + memset (buffer1, 0, sizeof (buffer1)); + + char buffer2[8]; + memset (buffer2, 0, sizeof (buffer2)); + + if (getrandom_full (buffer1, sizeof (buffer1), flags) + && getrandom_full (buffer2, sizeof (buffer2), flags)) + { + /* The probability that these two 8-byte buffers are equal + is very small (assuming that two subsequent calls to + getrandom result are independent, uniformly distributed + random variables). */ + if (memcmp (buffer1, buffer2, sizeof (buffer1)) == 0) + { + printf ("error: getrandom returns constant value\n"); + errors = true; + } + } + } +} + +static void +test_getentropy (void) +{ + char buf[16]; + memset (buf, '@', sizeof (buf)); + if (getentropy (buf, 0) != 0) + { + printf ("error: getentropy zero length: %m\n"); + errors = true; + return; + } + for (size_t i = 0; i < sizeof (buf); ++i) + if (buf[i] != '@') + { + printf ("error: getentropy modified zero-length buffer\n"); + errors = true; + return; + } + + if (getentropy (buf, sizeof (buf)) != 0) + { + printf ("error: getentropy buf: %m\n"); + errors = true; + return; + } + + char buf2[256]; + _Static_assert (sizeof (buf) < sizeof (buf2), "buf and buf2 compatible"); + memset (buf2, '@', sizeof (buf2)); + if (getentropy (buf2, sizeof (buf)) != 0) + { + printf ("error: getentropy buf2: %m\n"); + errors = true; + return; + } + + /* The probability that these two buffers are equal is very + small. */ + if (memcmp (buf, buf2, sizeof (buf) == 0)) + { + printf ("error: getentropy appears to return constant bytes\n"); + errors = true; + return; + } + + for (size_t i = sizeof (buf); i < sizeof (buf2); ++i) + if (buf2[i] != '@') + { + printf ("error: getentropy wrote beyond the end of the buffer\n"); + errors = true; + return; + } + + char buf3[257]; + if (getentropy (buf3, sizeof (buf3)) == 0) + { + printf ("error: getentropy successful for 257 byte buffer\n"); + errors = true; + return; + } + if (errno != EIO) + { + printf ("error: getentropy wrong error for 257 byte buffer: %m\n"); + errors = true; + return; + } +} + +static int +do_test (void) +{ + /* Check if getrandom is not supported by this system. */ + if (getrandom (NULL, 0, 0) == -1 && errno == ENOSYS) + return 77; + + for (int use_random = 0; use_random < 2; ++use_random) + for (int use_nonblock = 0; use_nonblock < 2; ++use_nonblock) + { + unsigned int flags = 0; + if (use_random) + flags |= GRND_RANDOM; + if (use_nonblock) + flags |= GRND_NONBLOCK; + test_flags (flags); + } + + test_getentropy (); + + return errors; +} + +#include <support/test-driver.c> |