Re: [PATCH v4] sev: add sev-inject-launch-secret

[Brijesh Singh]

On 10/14/20 10:17 AM, tobin@linux.ibm.com wrote:
> From: Tobin Feldman-Fitzthum <tobin@linux.ibm.com>
>
> AMD SEV allows a guest owner to inject a secret blob
> into the memory of a virtual machine. The secret is
> encrypted with the SEV Transport Encryption Key and
> integrity is guaranteed with the Transport Integrity
> Key. Although QEMU facilitates the injection of the
> launch secret, it cannot access the secret.
>
> Signed-off-by: Tobin Feldman-Fitzthum <tobin@linux.ibm.com>
> ---
>  include/monitor/monitor.h |  3 ++
>  include/sysemu/sev.h      |  2 ++
>  monitor/misc.c            |  8 +++---
>  qapi/misc-target.json     | 18 ++++++++++++
>  target/i386/monitor.c     |  7 +++++
>  target/i386/sev-stub.c    |  5 ++++
>  target/i386/sev.c         | 60 +++++++++++++++++++++++++++++++++++++++
>  target/i386/trace-events  |  1 +
>  8 files changed, 100 insertions(+), 4 deletions(-)
>
> diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
> index 348bfad3d5..af3887bb71 100644
> --- a/include/monitor/monitor.h
> +++ b/include/monitor/monitor.h
> @@ -4,6 +4,7 @@
>  #include "block/block.h"
>  #include "qapi/qapi-types-misc.h"
>  #include "qemu/readline.h"
> +#include "include/exec/hwaddr.h"
>  
>  typedef struct MonitorHMP MonitorHMP;
>  typedef struct MonitorOptions MonitorOptions;
> @@ -37,6 +38,8 @@ void monitor_flush(Monitor *mon);
>  int monitor_set_cpu(Monitor *mon, int cpu_index);
>  int monitor_get_cpu_index(Monitor *mon);
>  
> +void *gpa2hva(MemoryRegion **p_mr, hwaddr addr, uint64_t size, Error **errp);
> +
>  void monitor_read_command(MonitorHMP *mon, int show_prompt);
>  int monitor_read_password(MonitorHMP *mon, ReadLineFunc *readline_func,
>                            void *opaque);
> diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
> index 98c1ec8d38..7ab6e3e31d 100644
> --- a/include/sysemu/sev.h
> +++ b/include/sysemu/sev.h
> @@ -18,4 +18,6 @@
>  
>  void *sev_guest_init(const char *id);
>  int sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len);
> +int sev_inject_launch_secret(const char *hdr, const char *secret,
> +                             uint64_t gpa, Error **errp);
>  #endif
> diff --git a/monitor/misc.c b/monitor/misc.c
> index 4a859fb24a..f1ade245d5 100644
> --- a/monitor/misc.c
> +++ b/monitor/misc.c
> @@ -667,10 +667,10 @@ static void hmp_physical_memory_dump(Monitor *mon, 
> const QDict *qdict)
>      memory_dump(mon, count, format, size, addr, 1);
>  }
>  
> -static void *gpa2hva(MemoryRegion **p_mr, hwaddr addr, Error **errp)
> +void *gpa2hva(MemoryRegion **p_mr, hwaddr addr, uint64_t size, Error **errp)
>  {
>      MemoryRegionSection mrs = memory_region_find(get_system_memory(),
> -                                                 addr, 1);
> +                                                 addr, size);
>  
>      if (!mrs.mr) {
>          error_setg(errp, "No memory is mapped at address 0x%" HWADDR_PRIx, 
> addr);
> @@ -694,7 +694,7 @@ static void hmp_gpa2hva(Monitor *mon, const QDict *qdict)
>      MemoryRegion *mr = NULL;
>      void *ptr;
>  
> -    ptr = gpa2hva(&mr, addr, &local_err);
> +    ptr = gpa2hva(&mr, addr, 1, &local_err);
>      if (local_err) {
>          error_report_err(local_err);
>          return;
> @@ -770,7 +770,7 @@ static void hmp_gpa2hpa(Monitor *mon, const QDict *qdict)
>      void *ptr;
>      uint64_t physaddr;
>  
> -    ptr = gpa2hva(&mr, addr, &local_err);
> +    ptr = gpa2hva(&mr, addr, 1, &local_err);
>      if (local_err) {
>          error_report_err(local_err);
>          return;
> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
> index 1e561fa97b..4486a543ae 100644
> --- a/qapi/misc-target.json
> +++ b/qapi/misc-target.json
> @@ -201,6 +201,24 @@
>  { 'command': 'query-sev-capabilities', 'returns': 'SevCapability',
>    'if': 'defined(TARGET_I386)' }
>  
> +##
> +# @sev-inject-launch-secret:
> +#
> +# This command injects a secret blob into memory of SEV guest.
> +#
> +# @packet-header: the launch secret packet header encoded in base64
> +#
> +# @secret: the launch secret data to be injected encoded in base64
> +#
> +# @gpa: the guest physical address where secret will be injected.
> +#
> +# Since: 5.2
> +#
> +##
> +{ 'command': 'sev-inject-launch-secret',
> +  'data': { 'packet-header': 'str', 'secret': 'str', 'gpa': 'uint64' },
> +  'if': 'defined(TARGET_I386)' }
> +
>  ##
>  # @dump-skeys:
>  #
> diff --git a/target/i386/monitor.c b/target/i386/monitor.c
> index 7abae3c8df..f9d4951465 100644
> --- a/target/i386/monitor.c
> +++ b/target/i386/monitor.c
> @@ -728,3 +728,10 @@ SevCapability *qmp_query_sev_capabilities(Error **errp)
>  {
>      return sev_get_capabilities(errp);
>  }
> +
> +void qmp_sev_inject_launch_secret(const char *packet_hdr,
> +                                  const char *secret, uint64_t gpa,
> +                                  Error **errp)
> +{
> +    sev_inject_launch_secret(packet_hdr, secret, gpa, errp);
> +}
> diff --git a/target/i386/sev-stub.c b/target/i386/sev-stub.c
> index 88e3f39a1e..2d2ee54cc6 100644
> --- a/target/i386/sev-stub.c
> +++ b/target/i386/sev-stub.c
> @@ -49,3 +49,8 @@ SevCapability *sev_get_capabilities(Error **errp)
>      error_setg(errp, "SEV is not available in this QEMU");
>      return NULL;
>  }
> +int sev_inject_launch_secret(const char *hdr, const char *secret,
> +                             uint64_t gpa)
> +{
> +    return 1;
> +}
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index 93c4d60b82..5275a624b3 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -29,6 +29,8 @@
>  #include "trace.h"
>  #include "migration/blocker.h"
>  #include "qom/object.h"
> +#include "exec/address-spaces.h"
> +#include "monitor/monitor.h"
>  
>  #define TYPE_SEV_GUEST "sev-guest"
>  OBJECT_DECLARE_SIMPLE_TYPE(SevGuestState, SEV_GUEST)
> @@ -785,6 +787,64 @@ sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t 
> len)
>      return 0;
>  }
>  
> +int sev_inject_launch_secret(const char *packet_hdr, const char *secret,
> +                             uint64_t gpa, Error **errp)
> +{
> +    struct kvm_sev_launch_secret input;
> +    g_autofree guchar *data = NULL, *hdr = NULL;
> +    int error, ret = 1;
> +    void *hva;
> +    gsize hdr_sz = 0, data_sz = 0;
> +    MemoryRegion *mr = NULL;
> +
> +    /* secret can be injected only in this state */
> +    if (!sev_check_state(sev_guest, SEV_STATE_LAUNCH_SECRET)) {
> +        error_setg(errp, "SEV: Not in correct state. (LSECRET) %x",
> +                     sev_guest->state);
> +        return 1;
> +    }


Should we be checking the sev_guest variable is assigned before the
state check ? This will prevent an assert() if user calls the
sev_inject_launch_secret on non-SEV guest.


> +
> +    hdr = g_base64_decode(packet_hdr, &hdr_sz);
> +    if (!hdr || !hdr_sz) {
> +        error_setg(errp, "SEV: Failed to decode sequence header");
> +        return 1;
> +    }
> +
> +    data = g_base64_decode(secret, &data_sz);
> +    if (!data || !data_sz) {
> +        error_setg(errp, "SEV: Failed to decode data");
> +        return 1;
> +    }
> +
> +    hva = gpa2hva(&mr, gpa, data_sz, errp);
> +    if (!hva) {
> +        error_prepend(errp, "SEV: Failed to calculate guest address: ");
> +        return 1;
> +    }
> +
> +    input.hdr_uaddr = (uint64_t)(unsigned long)hdr;
> +    input.hdr_len = hdr_sz;
> +
> +    input.trans_uaddr = (uint64_t)(unsigned long)data;
> +    input.trans_len = data_sz;
> +
> +    input.guest_uaddr = (uint64_t)(unsigned long)hva;
> +    input.guest_len = data_sz;
> +
> +    trace_kvm_sev_launch_secret(gpa, input.guest_uaddr,
> +                                input.trans_uaddr, input.trans_len);
> +
> +    ret = sev_ioctl(sev_guest->sev_fd, KVM_SEV_LAUNCH_SECRET,
> +                    &input, &error);
> +    if (ret) {
> +        error_setg(errp, "SEV: failed to inject secret ret=%d fw_error=%d 
> '%s'",
> +                     ret, error, fw_error_to_str(error));
> +        return ret;
> +    }
> +
> +    return 0;
> +}
> +
>  static void
>  sev_register_types(void)
>  {
> diff --git a/target/i386/trace-events b/target/i386/trace-events
> index 789c700d4a..9f299e94a2 100644
> --- a/target/i386/trace-events
> +++ b/target/i386/trace-events
> @@ -15,3 +15,4 @@ kvm_sev_launch_start(int policy, void *session, void *pdh) 
> "policy 0x%x session
>  kvm_sev_launch_update_data(void *addr, uint64_t len) "addr %p len 0x%" PRIu64
>  kvm_sev_launch_measurement(const char *value) "data %s"
>  kvm_sev_launch_finish(void) ""
> +kvm_sev_launch_secret(uint64_t hpa, uint64_t hva, uint64_t secret, int len) 
> "hpa 0x%" PRIx64 " hva 0x%" PRIx64 " data 0x%" PRIx64 " len %d"