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Merged
merged 3 commits into from
Jul 28, 2022
Merged

Improve error messages in php_random_bytes() #9169

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cc06b6c
Improve error messages in php_random_bytes()
TimWolla Jul 27, 2022
76f2bca
Show strerror for `fstat` failures
TimWolla Jul 27, 2022
9413358
Improve messages when Windows/macOS CSPRNGs fail
TimWolla Jul 28, 2022
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30 changes: 24 additions & 6 deletions ext/random/random.c
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Original file line number Diff line number Diff line change
Expand Up @@ -470,7 +470,7 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
/* Defer to CryptGenRandom on Windows */
if (php_win32_get_random_bytes(bytes, size) == FAILURE) {
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Could not gather sufficient random data", 0);
zend_throw_exception(zend_ce_exception, "Failed to retrieve randomness from the operating system (BCryptGenRandom)", 0);
}
return FAILURE;
}
Expand All @@ -483,7 +483,7 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
*/
if (CCRandomGenerateBytes(bytes, size) != kCCSuccess) {
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Error generating bytes", 0);
zend_throw_exception(zend_ce_exception, "Failed to retrieve randomness from the operating system (CCRandomGenerateBytes)", 0);
}
return FAILURE;
}
Expand All @@ -496,6 +496,8 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
/* Linux getrandom(2) syscall or FreeBSD/DragonFlyBSD getrandom(2) function*/
/* Keep reading until we get enough entropy */
while (read_bytes < size) {
errno = 0;

/* Below, (bytes + read_bytes) is pointer arithmetic.

bytes read_bytes size
Expand All @@ -522,7 +524,7 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
/* Try again */
continue;
} else {
/* If the syscall fails, fall back to reading from /dev/urandom */
/* If the syscall fails, fall back to reading from /dev/urandom */
break;
}
}
Expand All @@ -539,15 +541,22 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
struct stat st;

if (fd < 0) {
errno = 0;
# if HAVE_DEV_URANDOM
fd = open("/dev/urandom", O_RDONLY);
# endif
if (fd < 0) {
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Cannot open source device", 0);
if (errno != 0) {
zend_throw_exception_ex(zend_ce_exception, 0, "Cannot open /dev/urandom: %s", strerror(errno));
} else {
zend_throw_exception_ex(zend_ce_exception, 0, "Cannot open /dev/urandom");
}
}
return FAILURE;
}

errno = 0;
/* Does the file exist and is it a character device? */
if (fstat(fd, &st) != 0 ||
# ifdef S_ISNAM
Expand All @@ -558,14 +567,19 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)
) {
close(fd);
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Error reading from source device", 0);
if (errno != 0) {
zend_throw_exception_ex(zend_ce_exception, 0, "Error reading from /dev/urandom: %s", strerror(errno));
} else {
zend_throw_exception_ex(zend_ce_exception, 0, "Error reading from /dev/urandom");
}
}
return FAILURE;
}
RANDOM_G(random_fd) = fd;
}

for (read_bytes = 0; read_bytes < size; read_bytes += (size_t) n) {
errno = 0;
n = read(fd, bytes + read_bytes, size - read_bytes);
if (n <= 0) {
break;
Expand All @@ -574,7 +588,11 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)

if (read_bytes < size) {
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Could not gather sufficient random data", 0);
if (errno != 0) {
zend_throw_exception_ex(zend_ce_exception, 0, "Could not gather sufficient random data: %s", strerror(errno));
} else {
zend_throw_exception_ex(zend_ce_exception, 0, "Could not gather sufficient random data");
}
}
return FAILURE;
}
Expand Down