Commit 899d9b8f authored by Nayna Jain's avatar Nayna Jain Committed by Michael Ellerman
Browse files

powerpc/pseries: Implement signed update for PLPKS objects 



The Platform Keystore provides a signed update interface which can be used
to create, replace or append to certain variables in the PKS in a secure
fashion, with the hypervisor requiring that the update be signed using the
Platform Key.

Implement an interface to the H_PKS_SIGNED_UPDATE hcall in the plpks
driver to allow signed updates to PKS objects.

(The plpks driver doesn't need to do any cryptography or otherwise handle
the actual signed variable contents - that will be handled by userspace
tooling.)

Signed-off-by: default avatarNayna Jain <nayna@linux.ibm.com>
[ajd: split patch, add timeout handling and misc cleanups]
Co-developed-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: default avatarRussell Currey <ruscur@russell.cc>
Reviewed-by: default avatarStefan Berger <stefanb@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230210080401.345462-18-ajd@linux.ibm.com
parent 119da30d

arch/powerpc/include/asm/hvcall.h

+1 −0
Original line number Diff line number Diff line
@@ -335,6 +335,7 @@ 
#define H_RPT_INVALIDATE	0x448

#define H_SCM_FLUSH		0x44C

#define H_GET_ENERGY_SCALE_INFO	0x450

#define H_PKS_SIGNED_UPDATE	0x454

#define H_WATCHDOG		0x45C

#define MAX_HCALL_OPCODE	H_WATCHDOG

arch/powerpc/include/asm/plpks.h

+5 −0
Original line number Diff line number Diff line
@@ -68,6 +68,11 @@ struct plpks_var_name_list { 
	struct plpks_var_name varlist[];

};



/**

 * Updates the authenticated variable. It expects NULL as the component.

 */

int plpks_signed_update_var(struct plpks_var *var, u64 flags);



/**

 * Writes the specified var and its data to PKS.

 * Any caller of PKS driver should present a valid component type for

arch/powerpc/platforms/pseries/plpks.c

+69 −5
Original line number Diff line number Diff line
@@ -81,6 +81,12 @@ static int pseries_status_to_err(int rc) 
		err = -ENOENT;

		break;

	case H_BUSY:

	case H_LONG_BUSY_ORDER_1_MSEC:

	case H_LONG_BUSY_ORDER_10_MSEC:

	case H_LONG_BUSY_ORDER_100_MSEC:

	case H_LONG_BUSY_ORDER_1_SEC:

	case H_LONG_BUSY_ORDER_10_SEC:

	case H_LONG_BUSY_ORDER_100_SEC:

		err = -EBUSY;

		break;

	case H_AUTHORITY:
@@ -184,14 +190,17 @@ static struct label *construct_label(char *component, u8 varos, u8 *name, 
				     u16 namelen)

{

	struct label *label;

	size_t slen;

	size_t slen = 0;



	if (!name || namelen > PLPKS_MAX_NAME_SIZE)

		return ERR_PTR(-EINVAL);



	// Support NULL component for signed updates

	if (component) {

		slen = strlen(component);

	if (component && slen > sizeof(label->attr.prefix))

		if (slen > sizeof(label->attr.prefix))

			return ERR_PTR(-EINVAL);

	}



	// The label structure must not cross a page boundary, so we align to the next power of 2

	label = kzalloc(roundup_pow_of_two(sizeof(*label)), GFP_KERNEL);
@@ -397,6 +406,61 @@ static int plpks_confirm_object_flushed(struct label *label, 
	return pseries_status_to_err(rc);

}



int plpks_signed_update_var(struct plpks_var *var, u64 flags)

{

	unsigned long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};

	int rc;

	struct label *label;

	struct plpks_auth *auth;

	u64 continuetoken = 0;

	u64 timeout = 0;



	if (!var->data || var->datalen <= 0 || var->namelen > PLPKS_MAX_NAME_SIZE)

		return -EINVAL;



	if (!(var->policy & PLPKS_SIGNEDUPDATE))

		return -EINVAL;



	// Signed updates need the component to be NULL.

	if (var->component)

		return -EINVAL;



	auth = construct_auth(PLPKS_OS_OWNER);

	if (IS_ERR(auth))

		return PTR_ERR(auth);



	label = construct_label(var->component, var->os, var->name, var->namelen);

	if (IS_ERR(label)) {

		rc = PTR_ERR(label);

		goto out;

	}



	do {

		rc = plpar_hcall9(H_PKS_SIGNED_UPDATE, retbuf,

				  virt_to_phys(auth), virt_to_phys(label),

				  label->size, var->policy, flags,

				  virt_to_phys(var->data), var->datalen,

				  continuetoken);



		continuetoken = retbuf[0];

		if (pseries_status_to_err(rc) == -EBUSY) {

			int delay_ms = get_longbusy_msecs(rc);

			mdelay(delay_ms);

			timeout += delay_ms;

		}

		rc = pseries_status_to_err(rc);

	} while (rc == -EBUSY && timeout < PLPKS_MAX_TIMEOUT);



	if (!rc)

		rc = plpks_confirm_object_flushed(label, auth);



	kfree(label);

out:

	kfree(auth);



	return rc;

}



int plpks_write_var(struct plpks_var var)

{

	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
@@ -443,7 +507,7 @@ int plpks_remove_var(char *component, u8 varos, struct plpks_var_name vname) 
	struct label *label;

	int rc;



	if (!component || vname.namelen > PLPKS_MAX_NAME_SIZE)

	if (vname.namelen > PLPKS_MAX_NAME_SIZE)

		return -EINVAL;



	auth = construct_auth(PLPKS_OS_OWNER);