[libvirt] [PATCH v5 10/20] tpm: Parse the capabilities supported by swtpm and swtpm_setup

[Stefan Berger]

Run 'swtpm socket --print-capabilities' and
'swtpm_setup --print-capabilities' to get the JSON object of the
features the programs are supporting and parse them into a bitmap.

Signed-off-by: Stefan Berger <stefanb at linux.ibm.com>
---
 src/libvirt_private.syms |   2 +
 src/util/virtpm.c        | 134 +++++++++++++++++++++++++++++++++++++--
 src/util/virtpm.h        |  15 +++++
 3 files changed, 147 insertions(+), 4 deletions(-)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 5b3c176862..5200adae3f 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -3181,6 +3181,8 @@ virTPMEmulatorInit;
 virTPMGetSwtpm;
 virTPMGetSwtpmIoctl;
 virTPMGetSwtpmSetup;
+virTPMSwtpmFeatureTypeFromString;
+virTPMSwtpmSetupFeatureTypeFromString;
 
 
 # util/virtypedparam.h
diff --git a/src/util/virtpm.c b/src/util/virtpm.c
index e4735f9c4d..692033e899 100644
--- a/src/util/virtpm.c
+++ b/src/util/virtpm.c
@@ -27,9 +27,22 @@
 #include "viralloc.h"
 #include "virfile.h"
 #include "virtpm.h"
+#include "vircommand.h"
+#include "virbitmap.h"
+#include "virjson.h"
 
 #define VIR_FROM_THIS VIR_FROM_NONE
 
+VIR_ENUM_IMPL(virTPMSwtpmFeature,
+              VIR_TPM_SWTPM_FEATURE_LAST,
+              "cmdarg-pwd-fd",
+);
+
+VIR_ENUM_IMPL(virTPMSwtpmSetupFeature,
+              VIR_TPM_SWTPM_SETUP_FEATURE_LAST,
+              "cmdarg-pwdfile-fd",
+);
+
 /**
  * virTPMCreateCancelPath:
  * @devpath: Path to the TPM device
@@ -74,17 +87,22 @@ virTPMCreateCancelPath(const char *devpath)
 }
 
 /*
- * executables for the swtpm; to be found on the host
+ * executables for the swtpm; to be found on the host along with
+ * capabilties bitmap
  */
 static char *swtpm_path;
 static struct stat swtpm_stat;
+static virBitmapPtr swtpm_caps;
 
 static char *swtpm_setup;
 static struct stat swtpm_setup_stat;
+static virBitmapPtr swtpm_setup_caps;
 
 static char *swtpm_ioctl;
 static struct stat swtpm_ioctl_stat;
 
+typedef int (*TypeFromStringFn)(const char *);
+
 const char *
 virTPMGetSwtpm(void)
 {
@@ -109,6 +127,99 @@ virTPMGetSwtpmIoctl(void)
     return swtpm_ioctl;
 }
 
+/* virTPMExecGetCaps
+ *
+ * Execute the prepared command and parse the returned JSON object
+ * to get the capabilities supported by the executable.
+ * A JSON object like this is expected:
+ *
+ * {
+ *  "type": "swtpm",
+ *  "features": [
+ *    "cmdarg-seccomp",
+ *    "cmdarg-key-fd",
+ *    "cmdarg-pwd-fd"
+ *  ]
+ * }
+ */
+static virBitmapPtr
+virTPMExecGetCaps(virCommandPtr cmd,
+                  TypeFromStringFn typeFromStringFn)
+{
+    int exitstatus;
+    virBitmapPtr bitmap;
+    VIR_AUTOFREE(char *) outbuf = NULL;
+    VIR_AUTOPTR(virJSONValue) json = NULL;
+    virJSONValuePtr featureList;
+    virJSONValuePtr item;
+    size_t idx;
+    const char *str;
+    int typ;
+
+    virCommandSetOutputBuffer(cmd, &outbuf);
+    if (virCommandRun(cmd, &exitstatus) < 0)
+        return NULL;
+
+    if (!(bitmap = virBitmapNewEmpty()))
+        return NULL;
+
+    /* older version does not support --print-capabilties -- that's fine */
+    if (exitstatus != 0)
+        return bitmap;
+
+    json = virJSONValueFromString(outbuf);
+    if (!json)
+        goto error_bad_json;
+
+    featureList = virJSONValueObjectGetArray(json, "features");
+    if (!featureList)
+        goto error_bad_json;
+
+    if (!virJSONValueIsArray(featureList))
+        goto error_bad_json;
+
+    for (idx = 0; idx < virJSONValueArraySize(featureList); idx++) {
+        item = virJSONValueArrayGet(featureList, idx);
+        if (!item)
+            continue;
+
+        str = virJSONValueGetString(item);
+        if (!str)
+            goto error_bad_json;
+        typ = typeFromStringFn(str);
+        if (typ < 0)
+            continue;
+
+        if (virBitmapSetBitExpand(bitmap, typ) < 0)
+            goto cleanup;
+    }
+
+ cleanup:
+    return bitmap;
+
+ error_bad_json:
+    virReportError(VIR_ERR_INTERNAL_ERROR,
+                   _("Unexpected JSON format: %s"), outbuf);
+    goto cleanup;
+}
+
+static virBitmapPtr
+virTPMGetCaps(TypeFromStringFn typeFromStringFn,
+                  const char *exec, const char *param1)
+{
+    VIR_AUTOPTR(virCommand) cmd = NULL;
+
+    if (!(cmd = virCommandNew(exec)))
+        return NULL;
+
+    if (param1)
+        virCommandAddArg(cmd, param1);
+    virCommandAddArg(cmd, "--print-capabilities");
+    virCommandClearCaps(cmd);
+
+    return virTPMExecGetCaps(cmd, typeFromStringFn);
+}
+
 /*
  * virTPMEmulatorInit
  *
@@ -122,16 +233,24 @@ virTPMEmulatorInit(void)
         const char *name;
         char **path;
         struct stat *stat;
+        const char *parm;
+        virBitmapPtr *caps;
+        TypeFromStringFn typeFromStringFn;
     } prgs[] = {
         {
             .name = "swtpm",
             .path = &swtpm_path,
             .stat = &swtpm_stat,
+            .parm = "socket",
+            .caps = &swtpm_caps,
+            .typeFromStringFn = virTPMSwtpmFeatureTypeFromString,
         },
         {
             .name = "swtpm_setup",
             .path = &swtpm_setup,
             .stat = &swtpm_setup_stat,
+            .caps = &swtpm_setup_caps,
+            .typeFromStringFn = virTPMSwtpmSetupFeatureTypeFromString,
         },
         {
             .name = "swtpm_ioctl",
@@ -142,7 +261,7 @@ virTPMEmulatorInit(void)
     size_t i;
 
     for (i = 0; i < ARRAY_CARDINALITY(prgs); i++) {
-        char *path;
+        VIR_AUTOFREE(char *) path = NULL;
         bool findit = *prgs[i].path == NULL;
         struct stat statbuf;
         char *tmp;
@@ -174,18 +293,25 @@ virTPMEmulatorInit(void)
                 virReportError(VIR_ERR_INTERNAL_ERROR,
                                _("%s is not an executable"),
                                path);
-                VIR_FREE(path);
                 return -1;
             }
             if (stat(path, prgs[i].stat) < 0) {
                 virReportSystemError(errno,
                                      _("Could not stat %s"), path);
-                VIR_FREE(path);
                 return -1;
             }
             tmp = *prgs[i].path;
             *prgs[i].path = path;
             VIR_FREE(tmp);
+
+            if (prgs[i].caps) {
+                *prgs[i].caps = virTPMGetCaps(prgs[i].typeFromStringFn,
+                                              path, prgs[i].parm);
+                path = NULL;
+                if (!*prgs[i].caps)
+                    return -1;
+            }
+            path = NULL;
         }
     }
 
diff --git a/src/util/virtpm.h b/src/util/virtpm.h
index 66d55fb231..f3dc40cd68 100644
--- a/src/util/virtpm.h
+++ b/src/util/virtpm.h
@@ -26,3 +26,18 @@ const char *virTPMGetSwtpm(void);
 const char *virTPMGetSwtpmSetup(void);
 const char *virTPMGetSwtpmIoctl(void);
 int virTPMEmulatorInit(void);
+
+typedef enum {
+    VIR_TPM_SWTPM_FEATURE_CMDARG_PWD_FD,
+
+    VIR_TPM_SWTPM_FEATURE_LAST
+} virTPMSwtpmFeature;
+
+typedef enum {
+    VIR_TPM_SWTPM_SETUP_FEATURE_CMDARG_PWDFILE_FD,
+
+    VIR_TPM_SWTPM_SETUP_FEATURE_LAST
+} virTPMSwtpmSetupFeature;
+
+VIR_ENUM_DECL(virTPMSwtpmFeature);
+VIR_ENUM_DECL(virTPMSwtpmSetupFeature);
-- 
2.20.1