Messages in this thread Patch in this message | | | Subject | Re: [PATCH] hibernation: on 32-bit x86, disabled in favor of KASLR | From | Evgenii Shatokhin <> | Date | Thu, 23 Mar 2017 16:23:45 +0300 |
| |
On 23.03.2017 03:27, Kees Cook wrote: > This is a modified revert of commit 65fe935dd238 ("x86/KASLR, x86/power: > Remove x86 hibernation restrictions"), since it appears that 32-bit > hibernation still can't support KASLR. 64-bit is fine. Since people have > been running with KASLR by default on 32-bit since v4.8, this disables > hibernation (with a warning). Booting with "nokaslr" will disable KASLR > and enable hibernation. > > Reported-by: Evgenii Shatokhin <eugene.shatokhin@yandex.ru> > Signed-off-by: Kees Cook <keescook@chromium.org> > Cc: stable@vger.kernel.org # v4.8+
The patch does not work as intended on my system, unfortunately.
I tried the mainline kernel v4.11-rc3 and added this patch. With "nokaslr" in the kernel command line, the system fails to hibernate. It complains this way in the log:
<...> kernel: PM: writing image. kernel: PM: Cannot find swap device, try swapon -a. kernel: PM: Cannot get swap writer kernel: PM: Basic memory bitmaps freed kernel: Restarting tasks ... done. systemd[1]: Time has been changed systemd[3948]: Time has been changed systemd[14825]: Time has been changed systemd[1]: systemd-hibernate.service: main process exited, code=exited, status=1/FAILURE systemd[1]: Failed to start Hibernate. <...>
The swap device (swap file, actually) is available, however: ------------- # swapon -s Filename Type Size Used Priority /swap file 6297596 0 -1 -------------
I built the same kernel without this patch then, added "nokaslr" in the kernel command line again, and the system hibernates and resumes fine.
> --- > Documentation/admin-guide/kernel-parameters.txt | 5 +++++ > arch/x86/boot/compressed/kaslr.c | 3 +++ > kernel/power/hibernate.c | 18 +++++++++++++++++- > 3 files changed, 25 insertions(+), 1 deletion(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 2ba45caabada..6f899c7f587d 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -1725,6 +1725,11 @@ > kernel and module base offset ASLR (Address Space > Layout Randomization). > > + On 32-bit x86 with CONFIG_HIBERNATION, hibernation > + is disabled if KASLR is enabled. If "nokaslr" is > + specified, KASLR will be diabled and hibernation > + will be enabled. > + > keepinitrd [HW,ARM] > > kernelcore= [KNL,X86,IA-64,PPC] > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c > index 8b7c9e75edcb..b694af45f1e0 100644 > --- a/arch/x86/boot/compressed/kaslr.c > +++ b/arch/x86/boot/compressed/kaslr.c > @@ -572,6 +572,9 @@ void choose_random_location(unsigned long input, > return; > } > > + if (IS_ENABLED(CONFIG_X86_32) && IS_ENABLED(CONFIG_HIBERNATION)) > + warn("KASLR active: hibernation disabled on 32-bit x86."); > + > boot_params->hdr.loadflags |= KASLR_FLAG; > > /* Prepare to add new identity pagetables on demand. */ > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c > index a8b978c35a6a..1d8f1fe1b7f4 100644 > --- a/kernel/power/hibernate.c > +++ b/kernel/power/hibernate.c > @@ -37,9 +37,14 @@ > #include "power.h" > > > -static int nocompress; > +#if defined(CONFIG_X86_32) && defined(CONFIG_RANDOMIZE_BASE) > +static int noresume = 1; > +static int nohibernate = 1; > +#else > static int noresume; > static int nohibernate; > +#endif > +static int nocompress; > static int resume_wait; > static unsigned int resume_delay; > static char resume_file[256] = CONFIG_PM_STD_PARTITION; > @@ -1194,3 +1199,14 @@ __setup("hibernate=", hibernate_setup); > __setup("resumewait", resumewait_setup); > __setup("resumedelay=", resumedelay_setup); > __setup("nohibernate", nohibernate_setup); > + > +/* Allow hibernation to be disabled in favor of KASLR on 32-bit x86. */ > +#if defined(CONFIG_X86_32) && defined(CONFIG_RANDOMIZE_BASE) > +static int __init nokaslr_hibernate_setup(char *str) > +{ > + noresume = 0; > + nohibernate = 0; > + return 1; > +} > +__setup("nokaslr", nokaslr_hibernate_setup); > +#endif >
| |