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firmware: enable run time change of forcing fallback loader

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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>
This commit is contained in:
Luis R. Rodriguez 2018-03-10 06:14:51 -08:00 committed by Greg Kroah-Hartman
parent 5d6d1ddd27
commit ceb1813224
4 changed files with 32 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/base/firmware_loader/fallback.c
View File

@ -7,6 +7,7 @@
#include <linux/security.h>
#include <linux/highmem.h>
#include <linux/umh.h>
#include <linux/sysctl.h>
#include "fallback.h"
#include "firmware.h"

4
drivers/base/firmware_loader/fallback.h
View File

@ -12,12 +12,14 @@
*
* @force_sysfs_fallback: force the sysfs fallback mechanism to be used
* as if one had enabled CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y.
* Useful to help debug a CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
* functionality on a kernel where that config entry has been disabled.
* @old_timeout: for internal use
* @loading_timeout: the timeout to wait for the fallback mechanism before
* giving up, in seconds.
*/
struct firmware_fallback_config {
const bool force_sysfs_fallback;
unsigned int force_sysfs_fallback;
int old_timeout;
int loading_timeout;
};

17
drivers/base/firmware_loader/fallback_table.c
View File

@ -19,6 +19,9 @@
/* Module or buit-in */
#ifdef CONFIG_FW_LOADER_USER_HELPER
static unsigned int zero;
static unsigned int one = 1;
struct firmware_fallback_config fw_fallback_config = {
.force_sysfs_fallback = IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
.loading_timeout = 60,
@ -26,4 +29,18 @@ struct firmware_fallback_config fw_fallback_config = {
};
EXPORT_SYMBOL_GPL(fw_fallback_config);
struct ctl_table firmware_config_table[] = {
{
.procname = "force_sysfs_fallback",
.data = &fw_fallback_config.force_sysfs_fallback,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_douintvec_minmax,
.extra1 = &zero,
.extra2 = &one,
},
{ }
};
EXPORT_SYMBOL_GPL(firmware_config_table);
#endif

11
kernel/sysctl.c
View File

@ -253,6 +253,10 @@ extern struct ctl_table random_table[];
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 @@ static struct ctl_table kern_table[] = {
.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,