usercopy: Enhance and rename report_usercopy()
In preparation for refactoring the usercopy checks to pass offset to
the hardened usercopy report, this renames report_usercopy() to the
more accurate usercopy_abort(), marks it as noreturn because it is,
adds a hopefully helpful comment for anyone investigating such reports,
makes the function available to the slab allocators, and adds new "detail"
and "offset" arguments.
Signed-off-by: Kees Cook <keescook@chromium.org>
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 251e655..38b6442 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -273,4 +273,10 @@
#define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0)
#endif
+#ifdef CONFIG_HARDENED_USERCOPY
+void __noreturn usercopy_abort(const char *name, const char *detail,
+ bool to_user, unsigned long offset,
+ unsigned long len);
+#endif
+
#endif /* __LINUX_UACCESS_H__ */
diff --git a/mm/usercopy.c b/mm/usercopy.c
index 5df1e68..8006baa 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -58,11 +58,25 @@
return GOOD_STACK;
}
-static void report_usercopy(unsigned long len, bool to_user, const char *type)
+/*
+ * If this function is reached, then CONFIG_HARDENED_USERCOPY has found an
+ * unexpected state during a copy_from_user() or copy_to_user() call.
+ * There are several checks being performed on the buffer by the
+ * __check_object_size() function. Normal stack buffer usage should never
+ * trip the checks, and kernel text addressing will always trip the check.
+ * For cache objects, copies must be within the object size.
+ */
+void __noreturn usercopy_abort(const char *name, const char *detail,
+ bool to_user, unsigned long offset,
+ unsigned long len)
{
- pr_emerg("kernel memory %s attempt detected %s '%s' (%lu bytes)\n",
- to_user ? "exposure" : "overwrite",
- to_user ? "from" : "to", type ? : "unknown", len);
+ pr_emerg("Kernel memory %s attempt detected %s %s%s%s%s (offset %lu, size %lu)!\n",
+ to_user ? "exposure" : "overwrite",
+ to_user ? "from" : "to",
+ name ? : "unknown?!",
+ detail ? " '" : "", detail ? : "", detail ? "'" : "",
+ offset, len);
+
/*
* For greater effect, it would be nice to do do_group_exit(),
* but BUG() actually hooks all the lock-breaking and per-arch
@@ -260,6 +274,6 @@
return;
report:
- report_usercopy(n, to_user, err);
+ usercopy_abort(err, NULL, to_user, 0, n);
}
EXPORT_SYMBOL(__check_object_size);
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 9b341584..ae39444 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -138,6 +138,7 @@
"__reiserfs_panic",
"lbug_with_loc",
"fortify_panic",
+ "usercopy_abort",
};
if (func->bind == STB_WEAK)