Merge from 3.1: Issue #13703: add a way to randomize the hash values of basic types (str, bytes, datetime)

in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.

The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.

1 files changed, 60 insertions, 0 deletions

diff --git a/Python/pytime.c b/Python/pytime.c
new file mode 100644
index 0000000000..6fb7695911
--- /dev/null
+++ b/Python/pytime.c
@@ -0,0 +1,60 @@
+#include "Python.h"
+
+#ifdef __APPLE__
+#if defined(HAVE_GETTIMEOFDAY) && defined(HAVE_FTIME)
+  /*
+   * _PyTime_gettimeofday falls back to ftime when getttimeofday fails because the latter
+   * might fail on some platforms. This fallback is unwanted on MacOSX because
+   * that makes it impossible to use a binary build on OSX 10.4 on earlier
+   * releases of the OS. Therefore claim we don't support ftime.
+   */
+# undef HAVE_FTIME
+#endif
+#endif
+
+#ifdef HAVE_FTIME
+#include <sys/timeb.h>
+#if !defined(MS_WINDOWS) && !defined(PYOS_OS2)
+extern int ftime(struct timeb *);
+#endif /* MS_WINDOWS */
+#endif /* HAVE_FTIME */
+
+void
+_PyTime_gettimeofday(_PyTime_timeval *tp)
+{
+    /* There are three ways to get the time:
+      (1) gettimeofday() -- resolution in microseconds
+      (2) ftime() -- resolution in milliseconds
+      (3) time() -- resolution in seconds
+      In all cases the return value in a timeval struct.
+      Since on some systems (e.g. SCO ODT 3.0) gettimeofday() may
+      fail, so we fall back on ftime() or time().
+      Note: clock resolution does not imply clock accuracy! */
+#ifdef HAVE_GETTIMEOFDAY
+#ifdef GETTIMEOFDAY_NO_TZ
+    if (gettimeofday(tp) == 0)
+        return;
+#else /* !GETTIMEOFDAY_NO_TZ */
+    if (gettimeofday(tp, (struct timezone *)NULL) == 0)
+        return;
+#endif /* !GETTIMEOFDAY_NO_TZ */
+#endif /* !HAVE_GETTIMEOFDAY */
+#if defined(HAVE_FTIME)
+    {
+        struct timeb t;
+        ftime(&t);
+        tp->tv_sec = t.time;
+        tp->tv_usec = t.millitm * 1000;
+    }
+#else /* !HAVE_FTIME */
+    tp->tv_sec = time(NULL);
+    tp->tv_usec = 0;
+#endif /* !HAVE_FTIME */
+    return;
+}
+
+void
+_PyTime_Init()
+{
+    /* Do nothing.  Needed to force linking. */
+}