Re: [PATCH 15/18] Hibernate: adapt to UEFI secure boot with signature check

[joeyli <jlee@suse.com>]

於 日，2013-08-25 於 18:42 +0200，Pavel Machek 提到：
> On Thu 2013-08-22 19:01:54, Lee, Chun-Yi wrote:
> > In current solution, the snapshot signature check used the RSA key-pair
> > that are generated by bootloader(e.g. shim) and pass the key-pair to
> > kernel through EFI variables. I choice to binding the snapshot
> > signature check mechanism with UEFI secure boot for provide stronger
> > protection of hibernate. Current behavior is following:
> > 
> >  + UEFI Secure Boot ON, Kernel found key-pair from shim:
> >    Will do the S4 signature check.
> > 
> >  + UEFI Secure Boot ON, Kernel didn't find key-pair from shim:
> >    Will lock down S4 function.
> > 
> >  + UEFI Secure Boot OFF
> >    Will NOT do the S4 signature check.
> >    Ignore any keys from bootloader.
> > 
> > v2:
> > Replace sign_key_data_loaded() by skey_data_available() to check sign key data
> > is available for hibernate.
> > 
> > Reviewed-by: Jiri Kosina <jkosina@suse.cz>
> > Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
> > ---
> >  kernel/power/hibernate.c |   36 +++++++++++++++++-
> >  kernel/power/main.c      |   11 +++++-
> >  kernel/power/snapshot.c  |   95 ++++++++++++++++++++++++++--------------------
> >  kernel/power/swap.c      |    4 +-
> >  kernel/power/user.c      |   11 +++++
> >  5 files changed, 112 insertions(+), 45 deletions(-)
> > 
> > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> > index c545b15..0f19f3d 100644
> > --- a/kernel/power/hibernate.c
> > +++ b/kernel/power/hibernate.c
> > @@ -29,6 +29,7 @@
> >  #include <linux/ctype.h>
> >  #include <linux/genhd.h>
> >  #include <linux/key.h>
> > +#include <linux/efi.h>
> >  
> >  #include "power.h"
> >  
> > @@ -632,7 +633,14 @@ static void power_down(void)
> >  int hibernate(void)
> >  {
> >  	int error;
> > -	int skey_error;
> > +
> > +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> > +	if (!capable(CAP_COMPROMISE_KERNEL) && !skey_data_available()) {
> > +#else
> > +	if (!capable(CAP_COMPROMISE_KERNEL)) {
> > +#endif
> > +		return -EPERM;
> > +	}
> >  
> >  	lock_system_sleep();
> >  	/* The snapshot device should not be opened while we're running */
> > @@ -799,6 +807,15 @@ static int software_resume(void)
> >  	if (error)
> >  		goto Unlock;
> >  
> > +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> > +	if (!capable(CAP_COMPROMISE_KERNEL) && !wkey_data_available()) {
> > +#else
> > +	if (!capable(CAP_COMPROMISE_KERNEL)) {
> > +#endif
> > +		mutex_unlock(&pm_mutex);
> > +		return -EPERM;
> > +	}
> > +
> >  	/* The snapshot device should not be opened while we're running */
> >  	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
> >  		error = -EBUSY;
> > @@ -892,6 +909,15 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
> >  	int i;
> >  	char *start = buf;
> >  
> > +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> > +	if (efi_enabled(EFI_SECURE_BOOT) && !skey_data_available()) {
> > +#else
> > +	if (efi_enabled(EFI_SECURE_BOOT)) {
> > +#endif
> > +		buf += sprintf(buf, "[%s]\n", "disabled");
> > +		return buf-start;
> > +	}
> > +
> >  	for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
> >  		if (!hibernation_modes[i])
> >  			continue;
> > @@ -926,6 +952,14 @@ static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
> >  	char *p;
> >  	int mode = HIBERNATION_INVALID;
> >  
> > +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> > +	if (!capable(CAP_COMPROMISE_KERNEL) && !skey_data_available()) {
> > +#else
> > +	if (!capable(CAP_COMPROMISE_KERNEL)) {
> > +#endif
> > +		return -EPERM;
> > +	}
> > +
> >  	p = memchr(buf, '\n', n);
> >  	len = p ? p - buf : n;
> >  
> 
> You clearly need some helper function.
> 									Pavel
> 

I will use a help function to replace those ifdef block.

Thanks for your suggestion!
Joey Lee