Skip to content

If getrandom syscall is unavailable (ENOSYS), try to fallback on /dev/urandom #2385

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

If getrandom syscall is unavailable (ENOSYS), try to fallback on /dev/urandom #2385

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
85 changes: 44 additions & 41 deletions ext/standard/random.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -93,14 +93,13 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, zend_bool should_throw)
}
#elif HAVE_DECL_ARC4RANDOM_BUF && ((defined(__OpenBSD__) && OpenBSD >= 201405) || (defined(__NetBSD__) && __NetBSD_Version__ >= 700000001))
arc4random_buf(bytes, size);
#elif defined(__linux__) && defined(SYS_getrandom)
/* Linux getrandom(2) syscall */
#else
size_t read_bytes = 0;
size_t amount_to_read = 0;
ssize_t n;

#if defined(__linux__) && defined(SYS_getrandom)
/* Linux getrandom(2) syscall */
/* Keep reading until we get enough entropy */
do {
while (read_bytes < size) {
/* Below, (bytes + read_bytes) is pointer arithmetic.

bytes read_bytes size
Expand All @@ -110,11 +109,16 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, zend_bool should_throw)
amount_to_read

*/
amount_to_read = size - read_bytes;
size_t amount_to_read = size - read_bytes;
n = syscall(SYS_getrandom, bytes + read_bytes, amount_to_read, 0);

if (n == -1) {
if (errno == EINTR || errno == EAGAIN) {
if (errno == ENOSYS) {
/* Try to fallback to /dev/urandom */
read_bytes = 0;
break;
}
else if (errno == EINTR || errno == EAGAIN) {
/* Try again */
continue;
}
Expand All @@ -130,53 +134,52 @@ PHPAPI int php_random_bytes(void *bytes, size_t size, zend_bool should_throw)
}

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;
}
#endif
if (read_bytes < size) {
int fd = RANDOM_G(fd);
struct stat st;

if (fd < 0) {
if (fd < 0) {
#if HAVE_DEV_URANDOM
fd = open("/dev/urandom", O_RDONLY);
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 (fd < 0) {
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Cannot open source device", 0);
}
return FAILURE;
}
return FAILURE;
}
/* Does the file exist and is it a character device? */
if (fstat(fd, &st) != 0 ||
/* Does the file exist and is it a character device? */
if (fstat(fd, &st) != 0 ||
# ifdef S_ISNAM
!(S_ISNAM(st.st_mode) || S_ISCHR(st.st_mode))
!(S_ISNAM(st.st_mode) || S_ISCHR(st.st_mode))
# else
!S_ISCHR(st.st_mode)
!S_ISCHR(st.st_mode)
# endif
) {
close(fd);
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Error reading from source device", 0);
) {
close(fd);
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Error reading from source device", 0);
}
return FAILURE;
}
return FAILURE;
RANDOM_G(fd) = fd;
}
RANDOM_G(fd) = fd;
}

while (read_bytes < size) {
n = read(fd, bytes + read_bytes, size - read_bytes);
if (n <= 0) {
break;
for (read_bytes = 0; read_bytes < size; read_bytes += (size_t) n) {
n = read(fd, bytes + read_bytes, size - read_bytes);
if (n <= 0) {
break;
}
}
read_bytes += n;
}

if (read_bytes < size) {
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Could not gather sufficient random data", 0);
if (read_bytes < size) {
if (should_throw) {
zend_throw_exception(zend_ce_exception, "Could not gather sufficient random data", 0);
}
return FAILURE;
}
return FAILURE;
}
#endif

Expand Down