[PATCH v4 21/24] powerpc/pseries: Pass PLPKS password on kexec

Andrew Donnellan
2023-01-20T07:44:49Z

From: Russell Currey <ruscur@russell.cc>

Before interacting with the PLPKS, we ask the hypervisor to generate a
password for the current boot, which is then required for most further
PLPKS operations.

If we kexec into a new kernel, the new kernel will try and fail to
generate a new password, as the password has already been set.

Pass the password through to the new kernel via the device tree, in
/chosen/plpks-pw. Check for the presence of this property before trying
to generate a new password - if it exists, use the existing password and
remove it from the device tree.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>

---

v3: New patch

v4: Fix compile when CONFIG_PSERIES_PLPKS=n (snowpatch)

Fix error handling on fdt_path_offset() call (ruscur)
---
arch/powerpc/kexec/file_load_64.c | 18 ++++++++++++++++++
arch/powerpc/platforms/pseries/plpks.c | 18 +++++++++++++++++-
2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index af8854f9eae3..0c9130af60cc 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -27,6 +27,7 @@
#include <asm/kexec_ranges.h>
#include <asm/crashdump-ppc64.h>
#include <asm/prom.h>
+#include <asm/plpks.h>

struct umem_info {
u64 *buf; /* data buffer for usable-memory property */
@@ -1156,6 +1157,9 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
{
struct crash_mem *umem = NULL, *rmem = NULL;
int i, nr_ranges, ret;
+#ifdef CONFIG_PSERIES_PLPKS
+ int chosen_offset;
+#endif

/*
* Restrict memory usage for kdump kernel by setting up
@@ -1230,6 +1234,20 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
}
}

+#ifdef CONFIG_PSERIES_PLPKS
+ // If we have PLPKS active, we need to provide the password
+ if (plpks_is_available()) {
+ chosen_offset = fdt_path_offset(fdt, "/chosen");
+ if (chosen_offset < 0) {
+ pr_err("Can't find chosen node: %s\n",
+ fdt_strerror(chosen_offset));
+ goto out;
+ }
+ ret = fdt_setprop(fdt, chosen_offset, "ibm,plpks-pw",
+ plpks_get_password(), plpks_get_passwordlen());
+ }
+#endif // CONFIG_PSERIES_PLPKS
+
out:
kfree(rmem);
kfree(umem);
diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
index b3c7410a4f13..0350f10e1755 100644
--- a/arch/powerpc/platforms/pseries/plpks.c
+++ b/arch/powerpc/platforms/pseries/plpks.c
@@ -16,6 +16,7 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/types.h>
+#include <linux/of.h>
#include <asm/hvcall.h>
#include <asm/machdep.h>
#include <asm/plpks.h>
@@ -126,7 +127,22 @@ static int plpks_gen_password(void)
{
unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
u8 *password, consumer = PLPKS_OS_OWNER;
- int rc;
+ struct property *prop;
+ int rc, len;
+
+ // Before we generate the password, we may have been booted by kexec and
+ // provided with a previous password. Check for that first.
+ prop = of_find_property(of_chosen, "ibm,plpks-pw", &len);
+ if (prop) {
+ ospasswordlength = (u16)len;
+ ospassword = kzalloc(ospasswordlength, GFP_KERNEL);
+ if (!ospassword) {
+ of_remove_property(of_chosen, prop);
+ return -ENOMEM;
+ }
+ memcpy(ospassword, prop->value, len);
+ return of_remove_property(of_chosen, prop);
+ }

// The password must not cross a page boundary, so we align to the next power of 2
password = kzalloc(roundup_pow_of_two(maxpwsize), GFP_KERNEL);
--
2.39.0