diff mbox series

[3/3] mm/usercopy: return 1 from hardened_usercopy __setup() handler

Message ID 20220222034249.14795-1-rdunlap@infradead.org (mailing list archive)
State New
Headers show
Series None | expand

Commit Message

Randy Dunlap Feb. 22, 2022, 3:42 a.m. UTC
__setup() handlers should return 1 if the command line option is handled
and 0 if not (or maybe never return 0; it just pollutes init's
environment). This prevents:

  Unknown kernel command line parameters \
  "BOOT_IMAGE=/boot/bzImage-517rc5 hardened_usercopy=off", will be \
  passed to user space.

  Run /sbin/init as init process
   with arguments:
   with environment:
but when "hardened_usercopy=foo" is used, there is no Unknown kernel
command line parameter.

Return 1 to indicate that the boot option has been handled.
Print a warning if strtobool() returns an error on the option string,
but do not mark this as in unknown command line option and do not cause
init's environment to be polluted with this string.

Fixes: b5cb15d9372ab ("usercopy: Allow boot cmdline disabling of hardening")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Sorry, I missed this third mm/ instance. Hence the patch 3/3.

 mm/usercopy.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series


--- linux-next-20220217.orig/mm/usercopy.c
+++ linux-next-20220217/mm/usercopy.c
@@ -284,7 +284,10 @@  static bool enable_checks __initdata = t
 static int __init parse_hardened_usercopy(char *str)
-	return strtobool(str, &enable_checks);
+	if (strtobool(str, &enable_checks))
+		pr_warn("Invalid option string for hardened_usercopy: '%s'\n",
+			str);
+	return 1;
 __setup("hardened_usercopy=", parse_hardened_usercopy);