firmware: enable run time change of forcing fallback loader
Currently one requires to test four kernel configurations to test the
firmware API completely:
0)
CONFIG_FW_LOADER=y
1)
o CONFIG_FW_LOADER=y
o CONFIG_FW_LOADER_USER_HELPER=y
2)
o CONFIG_FW_LOADER=y
o CONFIG_FW_LOADER_USER_HELPER=y
o CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
3) When CONFIG_FW_LOADER=m the built-in stuff is disabled, we have
no current tests for this.
We can reduce the requirements to three kernel configurations by making
fw_config.force_sysfs_fallback a proc knob we flip on off. For kernels that
disable CONFIG_IKCONFIG_PROC this can also enable one to inspect if
CONFIG_FW_LOADER_USER_HELPER_FALLBACK was enabled at build time by checking
the proc value at boot time.
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index f98f28c..bdf7090 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -253,6 +253,10 @@
extern struct ctl_table epoll_table[];
#endif
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+extern struct ctl_table firmware_config_table[];
+#endif
+
#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
int sysctl_legacy_va_layout;
#endif
@@ -748,6 +752,13 @@
.mode = 0555,
.child = usermodehelper_table,
},
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+ {
+ .procname = "firmware_config",
+ .mode = 0555,
+ .child = firmware_config_table,
+ },
+#endif
{
.procname = "overflowuid",
.data = &overflowuid,