Introduce structure for PTM_GET_CAPABILITY

include/swtpm/tpm_ioctl.h

@@ -31,6 +31,16 @@
 
 typedef uint32_t ptm_res;
 
+/* PTM_GET_CAPABILITY: Get supported capabilities (ioctl's) */
+struct ptm_cap_n {
+    union {
+        struct {
+            ptm_res tpm_result; /* will always be TPM_SUCCESS (0) */
+            uint32_t caps;
+        } resp; /* response */
+    } u;
+};
+
 /* PTM_GET_TPMESTABLISHED: get the establishment bit */
 struct ptm_est {
     union {
@@ -250,7 +260,8 @@ struct ptm_lockstorage {
     } u;
 };
 
-typedef uint64_t ptm_cap;
+typedef uint64_t ptm_cap; /* CUSE-only; use ptm_cap_n otherwise */
+typedef struct ptm_cap_n ptm_cap_n;
 typedef struct ptm_est ptm_est;
 typedef struct ptm_reset_est ptm_reset_est;
 typedef struct ptm_loc ptm_loc;

man/man3/swtpm_ioctls.pod

@@ -101,6 +101,20 @@ The PTM_LOCK_STORAGE ioctl or CMD_LOCK_STORAGE command is supported.
 
 =back
 
+=item B<PTM_GET_CAPABILITY / CMD_GET_CAPABILITY, ptm_cap_n>
+
+The ptm_cap_n data structure can be used for non-CUSE swtpm and
+looks as follows:
+
+ struct ptm_cap_n {
+    union {
+       struct {
+           ptm_res tpm_result; /* will always be TPM_SUCCESS (0) */
+           uint32_t caps;
+       } resp; /* response */
+    } u;
+ };
+
 =item B<PTM_INIT / CMD_INIT, ptm_init>
 
 This ioctl must be used to initialize the TPM. It must be sent to the

src/swtpm/ctrlchannel.c

@@ -438,9 +438,9 @@ static ssize_t ctrlchannel_recv_cmd(int fd,
     return recvd;
 }
 
-static uint64_t get_ptm_caps_supported(TPMLIB_TPMVersion tpmversion)
+static uint32_t get_ptm_caps_supported(TPMLIB_TPMVersion tpmversion)
 {
-    uint64_t caps =
+    uint32_t caps =
               PTM_CAP_INIT
             | PTM_CAP_SHUTDOWN
             | PTM_CAP_GET_TPMESTABLISHED
@@ -509,7 +509,7 @@ int ctrlchannel_process_fd(int fd,
     int *data_fd = NULL;
 
     /* Write-only */
-    ptm_cap *ptm_caps = (ptm_cap *)&output.body;
+    ptm_cap_n *ptm_caps_n = (ptm_cap_n *)&output.body;
     ptm_res *res_p = (ptm_res *)&output.body;
     ptm_est *te = (ptm_est *)&output.body;
     ptm_getconfig *pgc = (ptm_getconfig *)&output.body;
@@ -552,9 +552,11 @@ int ctrlchannel_process_fd(int fd,
 
     switch (be32toh(input.cmd)) {
     case CMD_GET_CAPABILITY:
-        *ptm_caps = htobe64(get_ptm_caps_supported(mlp->tpmversion));
+        /* must always succeed */
+        ptm_caps_n->u.resp.tpm_result = htobe32(TPM_SUCCESS);
+        ptm_caps_n->u.resp.caps = htobe32(get_ptm_caps_supported(mlp->tpmversion));
 
-        out_len = sizeof(*ptm_caps);
+        out_len = sizeof(*ptm_caps_n);
         break;
 
     case CMD_INIT:
@@ -917,6 +919,13 @@ int ctrlchannel_process_fd(int fd,
 send_resp:
     SWTPM_PrintAll(" Ctrl Rsp:", " ", output.body, min(out_len, 1024));
 
+    /* all error responses must only be 4 bytes long */
+    if (*res_p != htobe32(TPM_SUCCESS) && out_len != 4) {
+        logprintf(STDERR_FILENO, "Error: Response too long for cmd=0x%x : %u\n",
+                  be32toh(input.cmd), out_len);
+        out_len = sizeof(ptm_res);
+    }
+
     n = write_full(fd, output.body, out_len);
     if (n < 0) {
         logprintf(STDERR_FILENO,

src/swtpm_ioctl/tpm_ioctl.c

@@ -80,7 +80,6 @@
 #define devtoh32(is_chardev, x) (is_chardev ? x : be32toh(x))
 #define htodev32(is_chardev, x) (is_chardev ? x : htobe32(x))
 
-#define devtoh64(is_chardev, x) (is_chardev ? x : be64toh(x))
 #define htodev64(is_chardev, x) (is_chardev ? x : htobe64(x))
 
 /* for OpenBSD */
@@ -926,6 +925,7 @@ int main(int argc, char *argv[])
     ptm_reset_est reset_est;
     ptm_loc loc;
     ptm_cap cap;
+    ptm_cap_n cap_n;
     ptm_res res;
     ptm_init init;
     ptm_getconfig cfg;
@@ -1120,17 +1120,21 @@ int main(int argc, char *argv[])
     }
 
     if (!strcmp(command, "-c")) {
+        uint32_t caps;
         n = ctrlcmd(fd, PTM_GET_CAPABILITY, &cap, 0, sizeof(cap));
         if (n < 0) {
             fprintf(stderr,
                     "Could not execute PTM_GET_CAPABILITY: "
                     "%s\n", strerror(errno));
             goto exit;
         }
-        /* no tpm_result here */
-        printf("ptm capability is 0x%" PRIx64 "\n",
-               (uint64_t)devtoh64(is_chardev, cap));
-
+        if (is_chardev) {
+            caps = (uint32_t)cap;
+        } else {
+            memcpy(&cap_n, &cap, sizeof(cap_n));
+            caps = be32toh(cap_n.u.resp.caps);
+        }
+        printf("ptm capability is 0x%x\n", caps);
     } else if (!strcmp(command, "-i")) {
         init.u.req.init_flags = htodev32(is_chardev,
                                          PTM_INIT_FLAG_DELETE_VOLATILE);