qemu-vm: implement virtualization.tpm.provisioning

This option allows for TPM to provisionned before the control is handed
over to the qemu VM.

This is useful to add EK certificates.

The socket has been split in two, a server socket as well as the control
socket for compatibility with the tpm2-tss swtpm TCTI.

Because the control socket may now be used for provisioning, the swtpm
does not terminate when a client disconnects, and the stop of the swtpm
daemon is now controlled by a call to `swtpm_ioctl`.

nixos/modules/virtualisation/qemu-vm.nix

@@ -228,11 +228,38 @@ let
       ${lib.getExe cfg.tpm.package} \
         socket \
         --tpmstate dir="$NIX_SWTPM_DIR" \
-        --ctrl type=unixio,path="$NIX_SWTPM_DIR"/socket,terminate \
+        --server type=unixio,path="$NIX_SWTPM_DIR"/socket \
+        --ctrl type=unixio,path="$NIX_SWTPM_DIR"/socket.ctrl \
         --pid file="$NIX_SWTPM_DIR"/pid --daemon \
+        --flags not-need-init \
         --tpm2 \
         --log file="$NIX_SWTPM_DIR"/stdout,level=6
 
+      (
+        export TPM2TOOLS_TCTI=swtpm:path="$NIX_SWTPM_DIR"/socket
+        export PATH=${
+          lib.makeBinPath [
+            pkgs.tpm2-tools
+          ]
+        }:$PATH
+
+        tpm2_startup --clear
+        tpm2_startup
+
+        ${lib.optionalString (cfg.tpm.provisioning != null)
+          # Run provisioning in a subshell not to pollute vars
+          ''
+            (
+              export TCTI=swtpm:path="$NIX_SWTPM_DIR"/socket
+              ${cfg.tpm.provisioning}
+            )
+          ''
+        }
+
+        tpm2_shutdown
+        tpm2_shutdown --clear
+      )
+
       # Enable `fdflags` builtin in Bash
       # We will need it to perform surgical modification of the file descriptor
       # passed in the coprocess to remove `FD_CLOEXEC`, i.e. close the file descriptor
@@ -249,7 +276,7 @@ let
       # will stop it.
       coproc waitingswtpm {
         read || :
-        echo "" | ${lib.getExe hostPkgs.socat} STDIO UNIX-CONNECT:"$NIX_SWTPM_DIR"/socket
+        ${cfg.tpm.package}/bin/swtpm_ioctl --unix "$NIX_SWTPM_DIR"/socket.ctrl --stop 2>/dev/null
       }
       # Clear `FD_CLOEXEC` on the coprocess' file descriptor stdin.
       fdflags -s-cloexec ''${waitingswtpm[1]}
@@ -980,6 +1007,26 @@ in
         example = "tpm-tis-device";
         description = "QEMU device model for the TPM, uses the appropriate default based on th guest platform system and the package passed.";
       };
+
+      provisioning = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+        description = ''
+          Script to provision the TPM before control is handed off to the VM.
+
+          `TPM2TOOLS_TCTI` will be provided to configure tpm2-tools to use the
+          swtpm instance transparently.
+          `TCTI` is also provided as a generic value, consumer is expected to
+          re-export it however it may need (`TPM2OPENSSL_TCTI`, `TPM2_PKCS11_TCTI`,
+          ...).
+        '';
+        example = literalExpression ''
+          tpm2_nvdefine 0xcafecafe \
+            -C o \
+            -a "ownerread|policyread|policywrite|ownerwrite|authread|authwrite"
+          echo "foobar" | tpm2_nvwrite 0xcafecafe -C o
+        '';
+      };
     };
 
     virtualisation.useDefaultFilesystems = mkOption {
@@ -1198,7 +1245,7 @@ in
         "-nographic"
       ])
       (mkIf (cfg.tpm.enable) [
-        "-chardev socket,id=chrtpm,path=\"$NIX_SWTPM_DIR\"/socket"
+        "-chardev socket,id=chrtpm,path=\"$NIX_SWTPM_DIR\"/socket.ctrl"
         "-tpmdev emulator,id=tpm_dev_0,chardev=chrtpm"
         "-device ${cfg.tpm.deviceModel},tpmdev=tpm_dev_0"
       ])