Introduce lttng_copy_from_user_check_nofault

[lttng-modules.git] / probes / lttng-probe-user.h

diff --git a/probes/lttng-probe-user.h b/probes/lttng-probe-user.h
index 0939a18535853d798abed3590d60a966deeafe3f..3251f7c673f0dcc42dfdb0b73f655c4c767879f7 100644 (file)
--- a/probes/lttng-probe-user.h
+++ b/probes/lttng-probe-user.h
@@ -8,10 +8,33 @@
 #ifndef _LTTNG_PROBE_USER_H
 #define _LTTNG_PROBE_USER_H
 
+#include <wrapper/uaccess.h>
+
 /*
  * Calculate string length. Include final null terminating character if there is
  * one, or ends at first fault.
  */
 long lttng_strlen_user_inatomic(const char *addr);
 
+/*
+ * We use __copy_from_user_inatomic to copy userspace data after
+ * checking with access_ok() and disabling page faults.
+ *
+ * Return 0 if OK, nonzero on error.
+ */
+static inline
+unsigned long lttng_copy_from_user_check_nofault(void *dest,
+                                                const void __user *src,
+                                                unsigned long len)
+{
+       unsigned long ret;
+
+       if (!lttng_access_ok(VERIFY_READ, src, len))
+               return 1;
+       pagefault_disable();
+       ret = __copy_from_user_inatomic(dest, src, len);
+       pagefault_enable();
+       return ret;
+}
+
 #endif /* _LTTNG_PROBE_USER_H */