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