Issue #23853: Methods of SSL socket don't reset the socket timeout anymore each
time bytes are received or sent. The socket timeout is now the maximum total
duration of the method.
This change fixes a denial of service if the application is regulary
interrupted by a signal and the signal handler does not raise an exception.
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index bb838b0..b7b39dd 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -223,7 +223,7 @@
static PyObject *PySSL_SSLwrite(PySSLSocket *self, PyObject *args);
static PyObject *PySSL_SSLread(PySSLSocket *self, PyObject *args);
-static int PySSL_select(PySocketSockObject *s, int writing);
+static int PySSL_select(PySocketSockObject *s, int writing, _PyTime_t timeout);
static PyObject *PySSL_peercert(PySSLSocket *self, PyObject *args);
static PyObject *PySSL_cipher(PySSLSocket *self);
@@ -248,6 +248,10 @@
#define GET_SOCKET(obj) ((obj)->Socket ? \
(PySocketSockObject *) PyWeakref_GetObject((obj)->Socket) : NULL)
+/* If sock is NULL, use a timeout of 0 second */
+#define GET_SOCKET_TIMEOUT(sock) \
+ ((sock != NULL) ? (sock)->sock_timeout : 0)
+
/*
* SSL errors.
*/
@@ -565,6 +569,8 @@
int err;
int sockstate, nonblocking;
PySocketSockObject *sock = GET_SOCKET(self);
+ _PyTime_t timeout, deadline = 0;
+ int has_timeout;
if (sock) {
if (((PyObject*)sock) == Py_None) {
@@ -580,6 +586,11 @@
BIO_set_nbio(SSL_get_wbio(self->ssl), nonblocking);
}
+ timeout = GET_SOCKET_TIMEOUT(sock);
+ has_timeout = (timeout > 0);
+ if (has_timeout)
+ deadline = _PyTime_GetMonotonicClock() + timeout;
+
/* Actually negotiate SSL connection */
/* XXX If SSL_do_handshake() returns 0, it's also a failure. */
do {
@@ -591,10 +602,13 @@
if (PyErr_CheckSignals())
goto error;
+ if (has_timeout)
+ timeout = deadline - _PyTime_GetMonotonicClock();
+
if (err == SSL_ERROR_WANT_READ) {
- sockstate = PySSL_select(sock, 0);
+ sockstate = PySSL_select(sock, 0, timeout);
} else if (err == SSL_ERROR_WANT_WRITE) {
- sockstate = PySSL_select(sock, 1);
+ sockstate = PySSL_select(sock, 1, timeout);
} else {
sockstate = SOCKET_OPERATION_OK;
}
@@ -1611,7 +1625,7 @@
*/
static int
-PySSL_select(PySocketSockObject *s, int writing)
+PySSL_select(PySocketSockObject *s, int writing, _PyTime_t timeout)
{
int rc;
#ifdef HAVE_POLL
@@ -1624,10 +1638,14 @@
#endif
/* Nothing to do unless we're in timeout mode (not non-blocking) */
- if ((s == NULL) || (s->sock_timeout == 0))
+ if ((s == NULL) || (timeout == 0))
return SOCKET_IS_NONBLOCKING;
- else if (s->sock_timeout < 0)
- return SOCKET_IS_BLOCKING;
+ else if (timeout < 0) {
+ if (s->sock_timeout > 0)
+ return SOCKET_HAS_TIMED_OUT;
+ else
+ return SOCKET_IS_BLOCKING;
+ }
/* Guard against closed socket */
if (s->sock_fd < 0)
@@ -1639,8 +1657,8 @@
pollfd.fd = s->sock_fd;
pollfd.events = writing ? POLLOUT : POLLIN;
- /* s->sock_timeout is in seconds, timeout in ms */
- ms = (int)_PyTime_AsMilliseconds(s->sock_timeout, _PyTime_ROUND_CEILING);
+ /* timeout is in seconds, poll() uses milliseconds */
+ ms = (int)_PyTime_AsMilliseconds(timeout, _PyTime_ROUND_CEILING);
assert(ms <= INT_MAX);
PySSL_BEGIN_ALLOW_THREADS
@@ -1651,7 +1669,7 @@
if (!_PyIsSelectable_fd(s->sock_fd))
return SOCKET_TOO_LARGE_FOR_SELECT;
- _PyTime_AsTimeval_noraise(s->sock_timeout, &tv, _PyTime_ROUND_CEILING);
+ _PyTime_AsTimeval_noraise(timeout, &tv, _PyTime_ROUND_CEILING);
FD_ZERO(&fds);
FD_SET(s->sock_fd, &fds);
@@ -1679,6 +1697,8 @@
int err;
int nonblocking;
PySocketSockObject *sock = GET_SOCKET(self);
+ _PyTime_t timeout, deadline = 0;
+ int has_timeout;
if (sock != NULL) {
if (((PyObject*)sock) == Py_None) {
@@ -1707,7 +1727,12 @@
BIO_set_nbio(SSL_get_wbio(self->ssl), nonblocking);
}
- sockstate = PySSL_select(sock, 1);
+ timeout = GET_SOCKET_TIMEOUT(sock);
+ has_timeout = (timeout > 0);
+ if (has_timeout)
+ deadline = _PyTime_GetMonotonicClock() + timeout;
+
+ sockstate = PySSL_select(sock, 1, timeout);
if (sockstate == SOCKET_HAS_TIMED_OUT) {
PyErr_SetString(PySocketModule.timeout_error,
"The write operation timed out");
@@ -1731,10 +1756,13 @@
if (PyErr_CheckSignals())
goto error;
+ if (has_timeout)
+ timeout = deadline - _PyTime_GetMonotonicClock();
+
if (err == SSL_ERROR_WANT_READ) {
- sockstate = PySSL_select(sock, 0);
+ sockstate = PySSL_select(sock, 0, timeout);
} else if (err == SSL_ERROR_WANT_WRITE) {
- sockstate = PySSL_select(sock, 1);
+ sockstate = PySSL_select(sock, 1, timeout);
} else {
sockstate = SOCKET_OPERATION_OK;
}
@@ -1801,6 +1829,8 @@
int err;
int nonblocking;
PySocketSockObject *sock = GET_SOCKET(self);
+ _PyTime_t timeout, deadline = 0;
+ int has_timeout;
if (sock != NULL) {
if (((PyObject*)sock) == Py_None) {
@@ -1842,6 +1872,11 @@
BIO_set_nbio(SSL_get_wbio(self->ssl), nonblocking);
}
+ timeout = GET_SOCKET_TIMEOUT(sock);
+ has_timeout = (timeout > 0);
+ if (has_timeout)
+ deadline = _PyTime_GetMonotonicClock() + timeout;
+
do {
PySSL_BEGIN_ALLOW_THREADS
count = SSL_read(self->ssl, mem, len);
@@ -1851,10 +1886,13 @@
if (PyErr_CheckSignals())
goto error;
+ if (has_timeout)
+ timeout = deadline - _PyTime_GetMonotonicClock();
+
if (err == SSL_ERROR_WANT_READ) {
- sockstate = PySSL_select(sock, 0);
+ sockstate = PySSL_select(sock, 0, timeout);
} else if (err == SSL_ERROR_WANT_WRITE) {
- sockstate = PySSL_select(sock, 1);
+ sockstate = PySSL_select(sock, 1, timeout);
} else if (err == SSL_ERROR_ZERO_RETURN &&
SSL_get_shutdown(self->ssl) == SSL_RECEIVED_SHUTDOWN)
{
@@ -1908,6 +1946,8 @@
int err, ssl_err, sockstate, nonblocking;
int zeros = 0;
PySocketSockObject *sock = GET_SOCKET(self);
+ _PyTime_t timeout, deadline = 0;
+ int has_timeout;
if (sock != NULL) {
/* Guard against closed socket */
@@ -1924,6 +1964,11 @@
BIO_set_nbio(SSL_get_wbio(self->ssl), nonblocking);
}
+ timeout = GET_SOCKET_TIMEOUT(sock);
+ has_timeout = (timeout > 0);
+ if (has_timeout)
+ deadline = _PyTime_GetMonotonicClock() + timeout;
+
while (1) {
PySSL_BEGIN_ALLOW_THREADS
/* Disable read-ahead so that unwrap can work correctly.
@@ -1953,12 +1998,15 @@
continue;
}
+ if (has_timeout)
+ timeout = deadline - _PyTime_GetMonotonicClock();
+
/* Possibly retry shutdown until timeout or failure */
ssl_err = SSL_get_error(self->ssl, err);
if (ssl_err == SSL_ERROR_WANT_READ)
- sockstate = PySSL_select(sock, 0);
+ sockstate = PySSL_select(sock, 0, timeout);
else if (ssl_err == SSL_ERROR_WANT_WRITE)
- sockstate = PySSL_select(sock, 1);
+ sockstate = PySSL_select(sock, 1, timeout);
else
break;