diff mbox series

[1/6] efistub: pass uefi secureboot flag via fdt params

Message ID 20200904072905.25332-2-clin@suse.com
State New, archived
Headers show
Series add ima_arch support for ARM64 | expand

Commit Message

Chester Lin Sept. 4, 2020, 7:29 a.m. UTC
Add a new UEFI parameter: "linux,uefi-secure-boot" in fdt boot params
as other architectures have done in their own boot data. For example,
the boot_params->secure_boot in x86.

Signed-off-by: Chester Lin <clin@suse.com>
---
 drivers/firmware/efi/libstub/fdt.c | 39 +++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

Comments

Ard Biesheuvel Sept. 11, 2020, 3:01 p.m. UTC | #1
On Fri, 4 Sep 2020 at 10:29, Chester Lin <clin@suse.com> wrote:
>
> Add a new UEFI parameter: "linux,uefi-secure-boot" in fdt boot params
> as other architectures have done in their own boot data. For example,
> the boot_params->secure_boot in x86.
>
> Signed-off-by: Chester Lin <clin@suse.com>

Why do we need this flag? Can't the OS simply check the variable directly?

> ---
>  drivers/firmware/efi/libstub/fdt.c | 39 +++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
> index 11ecf3c4640e..c9a341e4715f 100644
> --- a/drivers/firmware/efi/libstub/fdt.c
> +++ b/drivers/firmware/efi/libstub/fdt.c
> @@ -136,6 +136,10 @@ static efi_status_t update_fdt(void *orig_fdt, unsigned long orig_fdt_size,
>         if (status)
>                 goto fdt_set_fail;
>
> +       status = fdt_setprop_var(fdt, node, "linux,uefi-secure-boot", fdt_val32);
> +       if (status)
> +               goto fdt_set_fail;
> +
>         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
>                 efi_status_t efi_status;
>
> @@ -199,6 +203,24 @@ static efi_status_t update_fdt_memmap(void *fdt, struct efi_boot_memmap *map)
>         return EFI_SUCCESS;
>  }
>
> +static efi_status_t update_fdt_secboot(void *fdt, u32 secboot)
> +{
> +       int node = fdt_path_offset(fdt, "/chosen");
> +       u32 fdt_val32;
> +       int err;
> +
> +       if (node < 0)
> +               return EFI_LOAD_ERROR;
> +
> +       fdt_val32 = cpu_to_fdt32(secboot);
> +
> +       err = fdt_setprop_inplace_var(fdt, node, "linux,uefi-secure-boot", fdt_val32);
> +       if (err)
> +               return EFI_LOAD_ERROR;
> +
> +       return EFI_SUCCESS;
> +}
> +
>  struct exit_boot_struct {
>         efi_memory_desc_t       *runtime_map;
>         int                     *runtime_entry_count;
> @@ -208,6 +230,9 @@ struct exit_boot_struct {
>  static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
>                                    void *priv)
>  {
> +       efi_status_t status;
> +       enum efi_secureboot_mode secboot_status;
> +       u32 secboot_var = 0;
>         struct exit_boot_struct *p = priv;
>         /*
>          * Update the memory map with virtual addresses. The function will also
> @@ -217,7 +242,19 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
>         efi_get_virtmap(*map->map, *map->map_size, *map->desc_size,
>                         p->runtime_map, p->runtime_entry_count);
>
> -       return update_fdt_memmap(p->new_fdt_addr, map);
> +       status = update_fdt_memmap(p->new_fdt_addr, map);
> +
> +       if (status != EFI_SUCCESS)
> +               return status;
> +
> +       secboot_status = efi_get_secureboot();
> +
> +       if (secboot_status == efi_secureboot_mode_enabled)
> +               secboot_var = 1;
> +
> +       status = update_fdt_secboot(p->new_fdt_addr, secboot_var);
> +
> +       return status;
>  }
>
>  #ifndef MAX_FDT_SIZE
> --
> 2.26.1
>
Chester Lin Sept. 14, 2020, 8:05 a.m. UTC | #2
Hi Ard,

On Fri, Sep 11, 2020 at 06:01:09PM +0300, Ard Biesheuvel wrote:
> On Fri, 4 Sep 2020 at 10:29, Chester Lin <clin@suse.com> wrote:
> >
> > Add a new UEFI parameter: "linux,uefi-secure-boot" in fdt boot params
> > as other architectures have done in their own boot data. For example,
> > the boot_params->secure_boot in x86.
> >
> > Signed-off-by: Chester Lin <clin@suse.com>
> 
> Why do we need this flag? Can't the OS simply check the variable directly?
> 

In fact, there's a difficulty to achieve this.

When linux kernel is booting on ARM, the runtime services are enabled later on.
It's done by arm_enable_runtime_services(), which is registered as an early_initcall.
Before it calls efi_native_runtime_setup(), all EFI runtime callbacks are still
NULL so calling efi.get_variable() will cause NULL pointer dereference.

There's a case that arch_ima_get_secureboot() can be called in early boot stage.
For example, when you try to set "ima_appraise=off" in kernel command line, it's
actually handled early:

[    0.000000] Kernel command line: BOOT_IMAGE=/boot/Image-5.9.0-rc3-9.gdd61cda-
vanilla root=UUID=a88bfb80-8abb-425c-a0f3-ad317465c28b splash=silent mitigations
=auto ignore_loglevel earlycon=pl011,mmio,0x9000000 console=ttyAMA0 ima_appraise=off
[    0.000000] ima: Secure boot enabled: ignoring ima_appraise=off boot parameter option
[    0.000000] Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes, linear)

However EFI services are remapped and enabled afterwards.

[    0.082286] rcu: Hierarchical SRCU implementation.
[    0.089592] Remapping and enabling EFI services.
[    0.097509] smp: Bringing up secondary CPUs ...

Another problem is that efi_rts_wq is created in subsys_initcall so we have to
wait for both EFI services mapping and the workqueue get initiated before calling
efi.get_variable() on ARM.

The only way I can think of is to put a flag via fdt params. May I have your
suggestions? I will appreciate if there's any better approach.

Thanks,
Chester

> > ---
> >  drivers/firmware/efi/libstub/fdt.c | 39 +++++++++++++++++++++++++++++-
> >  1 file changed, 38 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
> > index 11ecf3c4640e..c9a341e4715f 100644
> > --- a/drivers/firmware/efi/libstub/fdt.c
> > +++ b/drivers/firmware/efi/libstub/fdt.c
> > @@ -136,6 +136,10 @@ static efi_status_t update_fdt(void *orig_fdt, unsigned long orig_fdt_size,
> >         if (status)
> >                 goto fdt_set_fail;
> >
> > +       status = fdt_setprop_var(fdt, node, "linux,uefi-secure-boot", fdt_val32);
> > +       if (status)
> > +               goto fdt_set_fail;
> > +
> >         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
> >                 efi_status_t efi_status;
> >
> > @@ -199,6 +203,24 @@ static efi_status_t update_fdt_memmap(void *fdt, struct efi_boot_memmap *map)
> >         return EFI_SUCCESS;
> >  }
> >
> > +static efi_status_t update_fdt_secboot(void *fdt, u32 secboot)
> > +{
> > +       int node = fdt_path_offset(fdt, "/chosen");
> > +       u32 fdt_val32;
> > +       int err;
> > +
> > +       if (node < 0)
> > +               return EFI_LOAD_ERROR;
> > +
> > +       fdt_val32 = cpu_to_fdt32(secboot);
> > +
> > +       err = fdt_setprop_inplace_var(fdt, node, "linux,uefi-secure-boot", fdt_val32);
> > +       if (err)
> > +               return EFI_LOAD_ERROR;
> > +
> > +       return EFI_SUCCESS;
> > +}
> > +
> >  struct exit_boot_struct {
> >         efi_memory_desc_t       *runtime_map;
> >         int                     *runtime_entry_count;
> > @@ -208,6 +230,9 @@ struct exit_boot_struct {
> >  static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
> >                                    void *priv)
> >  {
> > +       efi_status_t status;
> > +       enum efi_secureboot_mode secboot_status;
> > +       u32 secboot_var = 0;
> >         struct exit_boot_struct *p = priv;
> >         /*
> >          * Update the memory map with virtual addresses. The function will also
> > @@ -217,7 +242,19 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
> >         efi_get_virtmap(*map->map, *map->map_size, *map->desc_size,
> >                         p->runtime_map, p->runtime_entry_count);
> >
> > -       return update_fdt_memmap(p->new_fdt_addr, map);
> > +       status = update_fdt_memmap(p->new_fdt_addr, map);
> > +
> > +       if (status != EFI_SUCCESS)
> > +               return status;
> > +
> > +       secboot_status = efi_get_secureboot();
> > +
> > +       if (secboot_status == efi_secureboot_mode_enabled)
> > +               secboot_var = 1;
> > +
> > +       status = update_fdt_secboot(p->new_fdt_addr, secboot_var);
> > +
> > +       return status;
> >  }
> >
> >  #ifndef MAX_FDT_SIZE
> > --
> > 2.26.1
> >
>
Chester Lin Oct. 5, 2020, 2:20 a.m. UTC | #3
On Mon, Sep 14, 2020 at 04:05:22PM +0800, Chester Lin wrote:
> Hi Ard,
> 
> On Fri, Sep 11, 2020 at 06:01:09PM +0300, Ard Biesheuvel wrote:
> > On Fri, 4 Sep 2020 at 10:29, Chester Lin <clin@suse.com> wrote:
> > >
> > > Add a new UEFI parameter: "linux,uefi-secure-boot" in fdt boot params
> > > as other architectures have done in their own boot data. For example,
> > > the boot_params->secure_boot in x86.
> > >
> > > Signed-off-by: Chester Lin <clin@suse.com>
> > 
> > Why do we need this flag? Can't the OS simply check the variable directly?
> > 
> 
> In fact, there's a difficulty to achieve this.
> 
> When linux kernel is booting on ARM, the runtime services are enabled later on.
> It's done by arm_enable_runtime_services(), which is registered as an early_initcall.
> Before it calls efi_native_runtime_setup(), all EFI runtime callbacks are still
> NULL so calling efi.get_variable() will cause NULL pointer dereference.
> 
> There's a case that arch_ima_get_secureboot() can be called in early boot stage.
> For example, when you try to set "ima_appraise=off" in kernel command line, it's
> actually handled early:
> 
> [    0.000000] Kernel command line: BOOT_IMAGE=/boot/Image-5.9.0-rc3-9.gdd61cda-
> vanilla root=UUID=a88bfb80-8abb-425c-a0f3-ad317465c28b splash=silent mitigations
> =auto ignore_loglevel earlycon=pl011,mmio,0x9000000 console=ttyAMA0 ima_appraise=off
> [    0.000000] ima: Secure boot enabled: ignoring ima_appraise=off boot parameter option
> [    0.000000] Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes, linear)
> 
> However EFI services are remapped and enabled afterwards.
> 
> [    0.082286] rcu: Hierarchical SRCU implementation.
> [    0.089592] Remapping and enabling EFI services.
> [    0.097509] smp: Bringing up secondary CPUs ...
> 
> Another problem is that efi_rts_wq is created in subsys_initcall so we have to
> wait for both EFI services mapping and the workqueue get initiated before calling
> efi.get_variable() on ARM.
> 
> The only way I can think of is to put a flag via fdt params. May I have your
> suggestions? I will appreciate if there's any better approach.
> 
> Thanks,
> Chester

Ping. May I have some suggestions here?

Thanks,
Chester

> 
> > > ---
> > >  drivers/firmware/efi/libstub/fdt.c | 39 +++++++++++++++++++++++++++++-
> > >  1 file changed, 38 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
> > > index 11ecf3c4640e..c9a341e4715f 100644
> > > --- a/drivers/firmware/efi/libstub/fdt.c
> > > +++ b/drivers/firmware/efi/libstub/fdt.c
> > > @@ -136,6 +136,10 @@ static efi_status_t update_fdt(void *orig_fdt, unsigned long orig_fdt_size,
> > >         if (status)
> > >                 goto fdt_set_fail;
> > >
> > > +       status = fdt_setprop_var(fdt, node, "linux,uefi-secure-boot", fdt_val32);
> > > +       if (status)
> > > +               goto fdt_set_fail;
> > > +
> > >         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
> > >                 efi_status_t efi_status;
> > >
> > > @@ -199,6 +203,24 @@ static efi_status_t update_fdt_memmap(void *fdt, struct efi_boot_memmap *map)
> > >         return EFI_SUCCESS;
> > >  }
> > >
> > > +static efi_status_t update_fdt_secboot(void *fdt, u32 secboot)
> > > +{
> > > +       int node = fdt_path_offset(fdt, "/chosen");
> > > +       u32 fdt_val32;
> > > +       int err;
> > > +
> > > +       if (node < 0)
> > > +               return EFI_LOAD_ERROR;
> > > +
> > > +       fdt_val32 = cpu_to_fdt32(secboot);
> > > +
> > > +       err = fdt_setprop_inplace_var(fdt, node, "linux,uefi-secure-boot", fdt_val32);
> > > +       if (err)
> > > +               return EFI_LOAD_ERROR;
> > > +
> > > +       return EFI_SUCCESS;
> > > +}
> > > +
> > >  struct exit_boot_struct {
> > >         efi_memory_desc_t       *runtime_map;
> > >         int                     *runtime_entry_count;
> > > @@ -208,6 +230,9 @@ struct exit_boot_struct {
> > >  static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
> > >                                    void *priv)
> > >  {
> > > +       efi_status_t status;
> > > +       enum efi_secureboot_mode secboot_status;
> > > +       u32 secboot_var = 0;
> > >         struct exit_boot_struct *p = priv;
> > >         /*
> > >          * Update the memory map with virtual addresses. The function will also
> > > @@ -217,7 +242,19 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
> > >         efi_get_virtmap(*map->map, *map->map_size, *map->desc_size,
> > >                         p->runtime_map, p->runtime_entry_count);
> > >
> > > -       return update_fdt_memmap(p->new_fdt_addr, map);
> > > +       status = update_fdt_memmap(p->new_fdt_addr, map);
> > > +
> > > +       if (status != EFI_SUCCESS)
> > > +               return status;
> > > +
> > > +       secboot_status = efi_get_secureboot();
> > > +
> > > +       if (secboot_status == efi_secureboot_mode_enabled)
> > > +               secboot_var = 1;
> > > +
> > > +       status = update_fdt_secboot(p->new_fdt_addr, secboot_var);
> > > +
> > > +       return status;
> > >  }
> > >
> > >  #ifndef MAX_FDT_SIZE
> > > --
> > > 2.26.1
> > >
> >
Ard Biesheuvel Oct. 12, 2020, 8:20 a.m. UTC | #4
On Mon, 5 Oct 2020 at 04:20, Chester Lin <clin@suse.com> wrote:
>
> On Mon, Sep 14, 2020 at 04:05:22PM +0800, Chester Lin wrote:
> > Hi Ard,
> >
> > On Fri, Sep 11, 2020 at 06:01:09PM +0300, Ard Biesheuvel wrote:
> > > On Fri, 4 Sep 2020 at 10:29, Chester Lin <clin@suse.com> wrote:
> > > >
> > > > Add a new UEFI parameter: "linux,uefi-secure-boot" in fdt boot params
> > > > as other architectures have done in their own boot data. For example,
> > > > the boot_params->secure_boot in x86.
> > > >
> > > > Signed-off-by: Chester Lin <clin@suse.com>
> > >
> > > Why do we need this flag? Can't the OS simply check the variable directly?
> > >
> >
> > In fact, there's a difficulty to achieve this.
> >
> > When linux kernel is booting on ARM, the runtime services are enabled later on.
> > It's done by arm_enable_runtime_services(), which is registered as an early_initcall.
> > Before it calls efi_native_runtime_setup(), all EFI runtime callbacks are still
> > NULL so calling efi.get_variable() will cause NULL pointer dereference.
> >
> > There's a case that arch_ima_get_secureboot() can be called in early boot stage.
> > For example, when you try to set "ima_appraise=off" in kernel command line, it's
> > actually handled early:
> >
> > [    0.000000] Kernel command line: BOOT_IMAGE=/boot/Image-5.9.0-rc3-9.gdd61cda-
> > vanilla root=UUID=a88bfb80-8abb-425c-a0f3-ad317465c28b splash=silent mitigations
> > =auto ignore_loglevel earlycon=pl011,mmio,0x9000000 console=ttyAMA0 ima_appraise=off
> > [    0.000000] ima: Secure boot enabled: ignoring ima_appraise=off boot parameter option
> > [    0.000000] Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes, linear)
> >
> > However EFI services are remapped and enabled afterwards.
> >
> > [    0.082286] rcu: Hierarchical SRCU implementation.
> > [    0.089592] Remapping and enabling EFI services.
> > [    0.097509] smp: Bringing up secondary CPUs ...
> >
> > Another problem is that efi_rts_wq is created in subsys_initcall so we have to
> > wait for both EFI services mapping and the workqueue get initiated before calling
> > efi.get_variable() on ARM.
> >
> > The only way I can think of is to put a flag via fdt params. May I have your
> > suggestions? I will appreciate if there's any better approach.
> >
> > Thanks,
> > Chester
>
> Ping. May I have some suggestions here?
>

IMA itself is initialized as a late initcall. The only reason you see
this message early is because this is where the parsing of the command
line parameter happens.

I'll send out a patch with a proposed solution for this issue.
diff mbox series

Patch

diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 11ecf3c4640e..c9a341e4715f 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -136,6 +136,10 @@  static efi_status_t update_fdt(void *orig_fdt, unsigned long orig_fdt_size,
 	if (status)
 		goto fdt_set_fail;
 
+	status = fdt_setprop_var(fdt, node, "linux,uefi-secure-boot", fdt_val32);
+	if (status)
+		goto fdt_set_fail;
+
 	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
 		efi_status_t efi_status;
 
@@ -199,6 +203,24 @@  static efi_status_t update_fdt_memmap(void *fdt, struct efi_boot_memmap *map)
 	return EFI_SUCCESS;
 }
 
+static efi_status_t update_fdt_secboot(void *fdt, u32 secboot)
+{
+	int node = fdt_path_offset(fdt, "/chosen");
+	u32 fdt_val32;
+	int err;
+
+	if (node < 0)
+		return EFI_LOAD_ERROR;
+
+	fdt_val32 = cpu_to_fdt32(secboot);
+
+	err = fdt_setprop_inplace_var(fdt, node, "linux,uefi-secure-boot", fdt_val32);
+	if (err)
+		return EFI_LOAD_ERROR;
+
+	return EFI_SUCCESS;
+}
+
 struct exit_boot_struct {
 	efi_memory_desc_t	*runtime_map;
 	int			*runtime_entry_count;
@@ -208,6 +230,9 @@  struct exit_boot_struct {
 static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
 				   void *priv)
 {
+	efi_status_t status;
+	enum efi_secureboot_mode secboot_status;
+	u32 secboot_var = 0;
 	struct exit_boot_struct *p = priv;
 	/*
 	 * Update the memory map with virtual addresses. The function will also
@@ -217,7 +242,19 @@  static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
 	efi_get_virtmap(*map->map, *map->map_size, *map->desc_size,
 			p->runtime_map, p->runtime_entry_count);
 
-	return update_fdt_memmap(p->new_fdt_addr, map);
+	status = update_fdt_memmap(p->new_fdt_addr, map);
+
+	if (status != EFI_SUCCESS)
+		return status;
+
+	secboot_status = efi_get_secureboot();
+
+	if (secboot_status == efi_secureboot_mode_enabled)
+		secboot_var = 1;
+
+	status = update_fdt_secboot(p->new_fdt_addr, secboot_var);
+
+	return status;
 }
 
 #ifndef MAX_FDT_SIZE