On Mon, Nov 13, 2023 at 11:01 PM Randy Dunlap <[email protected]> wrote:
>
> [add security & dhowells]
>
> On 11/13/23 18:23, Kelvie Wong wrote:
> > This allows the user to tell the kernel that they know better (namely,
> > they secured their swap properly), and that it can enable hibernation.
> >
> > I've been using this for about a year now, as it doesn't seem like
> > proper secure hibernation was going to be implemented back then, and
> > it's now been a year since I've been building my own kernels with this
> > patch, so getting this upstreamed would save some CO2 from me building
> > my own kernels every upgrade.
> >
> > Some other not-me users have also tested the patch:
> >
> > https://community.frame.work/t/guide-fedora-36-hibernation-with-enabled-secure-boot-and-full-disk-encryption-fde-decrypting-over-tpm2/25474/17
> >
> > Signed-off-by: Kelvie Wong <[email protected]>
> > ---
> > Documentation/admin-guide/kernel-parameters.txt | 5 +++++
> > kernel/power/hibernate.c | 10 +++++++++-
> > 2 files changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 426fa892d311..54785faba9e0 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -2804,6 +2804,11 @@
> > to extract confidential information from the kernel
> > are also disabled.
> >
> > + lockdown_hibernate [HIBERNATION]
> > + Enable hibernation even if lockdown is enabled. Enable this only if
> > + your swap is encrypted and secured properly, as an attacker can
> > + modify the kernel offline during hibernation.
> > +
> > locktorture.nreaders_stress= [KNL]
> > Set the number of locking read-acquisition kthreads.
> > Defaults to being automatically set based on the
> > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> > index 89c71fce225d..2221c531d54c 100644
> > --- a/kernel/power/hibernate.c
> > +++ b/kernel/power/hibernate.c
> > @@ -36,6 +36,7 @@
> > #include "power.h"
> >
> >
> > +static int lockdown_hibernate;
> > static int nocompress;
> > static int noresume;
> > static int nohibernate;
> > @@ -82,7 +83,7 @@ void hibernate_release(void)
> > bool hibernation_available(void)
> > {
> > return nohibernate == 0 &&
> > - !security_locked_down(LOCKDOWN_HIBERNATION) &&
> > + (lockdown_hibernate || !security_locked_down(LOCKDOWN_HIBERNATION)) &&
> > !secretmem_active() && !cxl_mem_active();
> > }
I would feel a lot better about this if there was a way to verify that
the swap was protected as opposed to leaving that as a note in a doc
that the majority of users will never see, read, or understand.
--
paul-moore.com
On Mon, 20 Nov 2023 at 13:12, Paul Moore <[email protected]> wrote:
> On Mon, Nov 13, 2023 at 11:01 PM Randy Dunlap <[email protected]> wrote:
> >
> > [add security & dhowells]
> >
> > On 11/13/23 18:23, Kelvie Wong wrote:
> > > This allows the user to tell the kernel that they know better (namely,
> > > they secured their swap properly), and that it can enable hibernation.
> > >
> > > I've been using this for about a year now, as it doesn't seem like
> > > proper secure hibernation was going to be implemented back then, and
> > > it's now been a year since I've been building my own kernels with this
> > > patch, so getting this upstreamed would save some CO2 from me building
> > > my own kernels every upgrade.
> > >
> > > Some other not-me users have also tested the patch:
> > >
> > > https://community.frame.work/t/guide-fedora-36-hibernation-with-enabled-secure-boot-and-full-disk-encryption-fde-decrypting-over-tpm2/25474/17
> > >
> > > Signed-off-by: Kelvie Wong <[email protected]>
>
> I would feel a lot better about this if there was a way to verify that
> the swap was protected as opposed to leaving that as a note in a doc
> that the majority of users will never see, read, or understand.
I'd argue that this wouldn't even be necessary if we detect the swap was
protected -- hibernation should just be enabled in that case without setting
any parameters.
My understanding is that it was disabled waiting for this
functionality, and it's been
at least a couple of years now [1], so it looks like it's not such an
easy problem.
Anyway, my argument is that the majority of users will never use this kernel
parameter anyway, so I think it's a fair assumption that the power users that
*do* use this will educate themselves on why this parameter even exists.
[1] https://lwn.net/Articles/847042/
--
Kelvie
On Mon, Nov 20, 2023 at 10:07 PM Kelvie Wong <[email protected]> wrote:
> On Mon, 20 Nov 2023 at 13:12, Paul Moore <[email protected]> wrote:
> > On Mon, Nov 13, 2023 at 11:01 PM Randy Dunlap <[email protected]> wrote:
> > >
> > > [add security & dhowells]
> > >
> > > On 11/13/23 18:23, Kelvie Wong wrote:
> > > > This allows the user to tell the kernel that they know better (namely,
> > > > they secured their swap properly), and that it can enable hibernation.
> > > >
> > > > I've been using this for about a year now, as it doesn't seem like
> > > > proper secure hibernation was going to be implemented back then, and
> > > > it's now been a year since I've been building my own kernels with this
> > > > patch, so getting this upstreamed would save some CO2 from me building
> > > > my own kernels every upgrade.
> > > >
> > > > Some other not-me users have also tested the patch:
> > > >
> > > > https://community.frame.work/t/guide-fedora-36-hibernation-with-enabled-secure-boot-and-full-disk-encryption-fde-decrypting-over-tpm2/25474/17
> > > >
> > > > Signed-off-by: Kelvie Wong <[email protected]>
> >
> > I would feel a lot better about this if there was a way to verify that
> > the swap was protected as opposed to leaving that as a note in a doc
> > that the majority of users will never see, read, or understand.
>
> I'd argue that this wouldn't even be necessary if we detect the swap was
> protected -- hibernation should just be enabled in that case without setting
> any parameters.
>
> My understanding is that it was disabled waiting for this
> functionality, and it's been
> at least a couple of years now [1], so it looks like it's not such an
> easy problem.
I've got to warn you that I have an allergic reaction to arguments
that start with "the right solution is really hard, so let's pick the
easier, worse solution." ;)
> Anyway, my argument is that the majority of users will never use this kernel
> parameter anyway, so I think it's a fair assumption that the power users that
> *do* use this will educate themselves on why this parameter even exists.
I guess I'm still not sold on this idea, I'm sorry.
--
paul-moore.com
On Tue, 21 Nov 2023 at 20:53, Paul Moore <[email protected]> wrote:
> On Mon, Nov 20, 2023 at 10:07 PM Kelvie Wong <[email protected]> wrote:
> > On Mon, 20 Nov 2023 at 13:12, Paul Moore <[email protected]> wrote:
> > > On Mon, Nov 13, 2023 at 11:01 PM Randy Dunlap <[email protected]> wrote:
> > > >
> > > > [add security & dhowells]
> > > >
> > > > On 11/13/23 18:23, Kelvie Wong wrote:
> > > > > This allows the user to tell the kernel that they know better (namely,
> > > > > they secured their swap properly), and that it can enable hibernation.
> > > > >
> > > > > I've been using this for about a year now, as it doesn't seem like
> > > > > proper secure hibernation was going to be implemented back then, and
> > > > > it's now been a year since I've been building my own kernels with this
> > > > > patch, so getting this upstreamed would save some CO2 from me building
> > > > > my own kernels every upgrade.
> > > > >
> > > > > Some other not-me users have also tested the patch:
> > > > >
> > > > > https://community.frame.work/t/guide-fedora-36-hibernation-with-enabled-secure-boot-and-full-disk-encryption-fde-decrypting-over-tpm2/25474/17
> > > > >
> > > > > Signed-off-by: Kelvie Wong <[email protected]>
> > >
> > > I would feel a lot better about this if there was a way to verify that
> > > the swap was protected as opposed to leaving that as a note in a doc
> > > that the majority of users will never see, read, or understand.
> >
> I've got to warn you that I have an allergic reaction to arguments
> that start with "the right solution is really hard, so let's pick the
> easier, worse solution." ;)
>
> I guess I'm still not sold on this idea, I'm sorry.
Not a problem, thanks for looking.
I do hope that hibernate on lockdown is one day properly supported though. I'd
imagine that lockdown will eventually be the default for most distros, and it'd
be a real shame to have to sacrifice hibernate for it (which is, in my opinion,
indispensable for laptop use).
Cheers,
--
Kelvie