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powerpc/pseries: Implement signed update for PLPKS objects

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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: Nayna Jain <nayna@linux.ibm.com>
[ajd: split patch, add timeout handling and misc cleanups]
Co-developed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230210080401.345462-18-ajd@linux.ibm.com
This commit is contained in:
Nayna Jain 2023-02-10 19:03:52 +11:00 committed by Michael Ellerman
parent 119da30d03
commit 899d9b8fee
3 changed files with 75 additions and 5 deletions
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1
arch/powerpc/include/asm/hvcall.h
View file

@ -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

5
arch/powerpc/include/asm/plpks.h
View file

@ -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

74
arch/powerpc/platforms/pseries/plpks.c
View file

@ -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);
slen = strlen(component);
if (component && slen > sizeof(label->attr.prefix))
return ERR_PTR(-EINVAL);
// Support NULL component for signed updates
if (component) {
slen = strlen(component);
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);